CN117337454A - Electronic equipment - Google Patents

Abstract

One embodiment of the present invention provides a novel display device having excellent convenience and reliability. The display device includes a plurality of flexible substrates on which a plurality of light emitting diode chips are mounted, a substrate provided with a nitride film, and a resin between the flexible substrates and the substrate provided with the nitride film, light emitted from the light emitting diode chips passing through the substrate provided with the nitride film.

Description

Electronic equipment

Technical Field

One embodiment of the present invention relates to an electronic device, a display device, a method for manufacturing the display device, and an apparatus for manufacturing the display device.

Note that one embodiment of the present invention is not limited to the above-described technical field. As an example of the technical field of one embodiment of the present invention disclosed in the present specification, a semiconductor device, a display device, a light-emitting device, a power storage device, a storage device, an electronic device, a lighting device, an input/output device, a driving method thereof, or a manufacturing method thereof can be given.

Note that in this specification, a semiconductor device refers to all devices that can operate by utilizing semiconductor characteristics. Transistors, semiconductor circuits, arithmetic devices, and memory devices are one embodiment of semiconductor devices. In addition, imaging devices, electro-optical devices, power generation devices (including thin film solar cells, organic thin film solar cells), and electronic devices sometimes include semiconductor devices.

Background

In recent years, the use of display devices has been diversified, and for example, display devices are used for portable information terminals, home television devices (also called televisions or television receivers), digital Signage (Digital Signage), and PID (Public Information Display: public information display). The display device typically includes a display device including a light-emitting element represented by an organic EL (Electro Luminescence: electroluminescence) element or a light-emitting diode (LED: light Emitting Diode), a display device including a liquid crystal element, and electronic paper for displaying by electrophoresis. In addition, in order to meet outdoor use demands, the brightness requirements of displays are increasing year by year.

An active matrix Micro LED display device using a small LED (also referred to as Micro LED) as a light emitting element and a transistor as a switching element connected to each pixel electrode has been disclosed (patent documents 1, 2, 3, 4).

[ Prior Art literature ]

[ patent literature ]

[ patent document 1] WO2020/065472

[ patent document 2] WO2019/220265

[ patent document 3] WO2020/049392

[ patent document 4] WO2020/049397

Disclosure of Invention

Technical problem to be solved by the invention

In a display device using Micro LEDs for a display element, a long time is required in a process of mounting the LEDs on a circuit board, and there is a problem in that manufacturing cost is reduced. In addition, the larger the number of pixels of the display device, the larger the number of LEDs to be mounted, so that the time required for mounting becomes longer. In addition, the higher the definition of the display device, the higher the difficulty in mounting the LED.

In view of the above-described problems, one of the objects of one embodiment of the present invention is to reduce the manufacturing cost of a display device using Micro LEDs for display elements. In addition, it is an object of one embodiment of the present invention to provide a display device using Micro LEDs of a larger area for display elements. Another object of one embodiment of the present invention is to provide a display device including a display surface having a curved surface and using a Micro LED having a large area for a display element.

In addition, an object of one embodiment of the present invention is to manufacture a display device using Micro LEDs for display elements with high yield.

An object of one embodiment of the present invention is to provide a display device with high brightness. Another object of one embodiment of the present invention is to provide a display device with high contrast. Another object of one embodiment of the present invention is to provide a display device with a high response speed. Another object of one embodiment of the present invention is to provide a display device with low power consumption. Another object of one embodiment of the present invention is to provide a display device which is inexpensive to manufacture. Another object of one embodiment of the present invention is to provide a display device with a long lifetime. Another object of one embodiment of the present invention is to provide a novel display device.

Note that the description of these objects does not hinder the existence of other objects. Furthermore, not all of the above objects need be achieved in one embodiment of the present invention. Further, the objects other than the above can be extracted from the description of the specification, drawings, and claims.

Means for solving the technical problems

A display device for a member provided in an automobile is realized by combining a display device using a plurality of Micro LEDs or a plurality of Mini LEDs for a display element. Specifically, a display having a curved display surface is provided as a vehicle interior decoration of an automobile.

In one embodiment of the present invention, a display device having a display surface with a curved surface is realized by using a flexible substrate, mounting a plurality of Micro LEDs or a plurality of Mini LEDs in a wiring layer provided on the flexible substrate, and then fixing the flexible substrate to a support having a curved surface. The curved surface of the support body has a convex shape or a concave shape.

In order to improve the yield, it is preferable to manufacture a display device having one display surface by manufacturing a set of a certain number of Micro LEDs using a substrate having flexibility and then combining a plurality of substrates having flexibility.

In addition, in order to improve reliability, a structure is provided in which a plurality of Micro LEDs or a plurality of Mini LEDs are sandwiched between cover materials (one or two) provided with barrier films, and are used in the up and down directions of a display device of a display element. A resin is provided between the cover material and the light emitting element. In addition, by using a material having light transmittance for the cover material and the resin, light may be emitted from the light-emitting element not only in one direction but also in two or more directions.

One embodiment of the present invention disclosed in this specification is a display device including a plurality of substrates having flexibility, a substrate provided with a nitride film, and a resin between the substrates having flexibility and the substrate provided with the nitride film, on which a plurality of light emitting diode chips (LED chips) are mounted, light emitted from the light emitting diode chips passing through the substrate provided with the nitride film.

In the above structure, the substrate having flexibility, the substrate provided with the nitride film, or the resin preferably has light transmittance. The refractive index of the above materials is preferably the same. The substrate held up and down for sealing is referred to as an acrylic resin, and may be referred to as a cover material. The nitride film provided on the substrate is referred to as a silicon nitride film, and may be referred to as a barrier film. The difference in refractive index n between the cover material and the resin is preferably 20% or less, more preferably 10% or less, and still more preferably 5% or less. Note that the refractive index means visible light, specifically, a value of light having a wavelength of 400nm to 750nm, and an average refractive index of light having a wavelength within the above range. The average refractive index is a value obtained by dividing the sum of the measured values of refractive index with respect to each light having a wavelength within the above range by the number of measurement points. Note that the refractive index of air is 1.

Note that although a substrate having flexibility and a substrate provided with a nitride film are referred to as a "substrate", they are sometimes referred to as a "thin film" depending on the material and thickness.

In the above configuration, the display device disclosed in the present specification may be a display device which is fixed to a support having a curved surface and at least a part of a display surface of the display device has a curved surface. When the substrate is fixed to a support having a curved surface, a substrate having a thin thickness is preferably used as a substrate having flexibility and a substrate provided with a nitride film.

In order to increase the area, a plurality of Micro LEDs or a plurality of Mini LEDs are mounted on each of the flexible substrates, and then each of the Micro LEDs or the Mini LEDs is arranged in a spliced state, thereby manufacturing a display device having one display surface.

Each of the plurality of substrates (or element layers) having flexibility is cut with a laser before being arranged in a splice shape. The depth is controlled by laser light, whereby convex portions and concave portions are formed on the end surfaces. As the laser light, a continuous oscillation laser light or a pulse oscillation laser light can be used. In particular, the pulse oscillation laser can instantaneously oscillate out high-energy pulse laser, So it is preferable. Examples of the pulse oscillation laser include Ar laser, kr laser, excimer laser, and CO ₂ Laser, YAG laser, Y ₂ O ₃ Laser, YVO ₄ Laser, YLF laser, YAlO ₃ Laser, glass laser, ruby laser, emerald laser, titanium ruby laser, copper vapor laser, or gold vapor laser. The wavelength of the laser light is preferably 200nm to 20. Mu.m. For example, CO having a wavelength of 10.6 μm can be used as the laser light ₂ And (5) laser. CO ₂ The laser may process a thin film or a glass substrate made of an organic material or an inorganic material. In the case of using a pulse laser as the laser light, the pulse width is preferably 10ps (picoseconds) to 10 μs (microseconds), more preferably 10ps to 1 μs, and even more preferably 10ps to 1ns (nanoseconds). For example, a pulse laser having a wavelength of 532nm and a pulse width of 1ns or less may be used.

One embodiment of the present invention disclosed in the present specification is a method for manufacturing an electronic device, including the steps of: forming a first pixel region including a first light emitting diode chip on a first substrate; forming a second pixel region including a second light emitting diode chip on a second substrate, the plurality of first light emitting diode chips being arranged adjacent to each other at equal intervals in a first direction on the first pixel region; before the first light emitting diode chip and the second light emitting diode chip are arranged in alignment so as to coincide with the first direction, the end of the first substrate and the end of the first pixel region are partially cut off by scanning the laser light in a second direction intersecting the first direction to form a convex portion; partially cutting off the end of the second substrate and the end of the second pixel region with laser light to form a concave portion; the convex portion and the concave portion are fitted to fix the first pixel region and the second pixel region in an adjacent manner.

In the above structure, the first light emitting diode chip and the second light emitting diode chip are fixed on the curved surface.

In addition, in the above structure, a transistor is included between the second substrate and the first light emitting diode chip.

In the above structure, the first substrate and the second substrate are flexible substrates.

In each of the above-described configurations, the first light-emitting diode chip and the second light-emitting diode chip each include light-emitting elements, and the light-emitting elements that emit light of the first color, the light-emitting elements that emit light of the second color, and the light-emitting elements that emit light of the third color are mounted in a matrix on the pixel region. Various methods for arranging the led chips include stripe type, mosaic type, and Delta type. Further, the light-emitting element that emits one light-emitting color on one light-emitting diode chip is not limited, and light-emitting elements that emit three light-emitting colors on one light-emitting diode chip may be provided in advance.

One embodiment of the present invention disclosed in the present specification is an electronic device including a display device including a plurality of light emitting diode chips and a support body having a curved surface and a plurality of electrodes formed along the curved surface, the plurality of light emitting diode chips being electrically connected to the plurality of electrodes.

The electronic device may have a structure including a wiring layer in contact with a support, the structure including a display device and a support, the display device including a plurality of light emitting diode chips and a flexible substrate on which the plurality of light emitting diode chips are mounted, the support having a curved surface and a plurality of electrodes formed along the curved surface, the flexible substrate including a wiring layer electrically connected to the plurality of electrodes, the plurality of light emitting diode chips being electrically connected to the plurality of electrodes through the wiring layer.

In each of the above-described configurations, the plurality of light emitting diode chips each include a light emitting element, and in the pixel region, a first light emitting element is adjacent to a second light emitting element in a first direction, and the first light emitting element is adjacent to a third light emitting element in a second direction, the second direction intersecting the first direction, the first light emitting element and the second light emitting element emitting light of different colors, and the first light emitting element and the third light emitting element emitting light of the same color.

In each of the above-described structures, a substantially high-definition display device can be provided by improving the arrangement of the light emitting elements, in which each of the plurality of light emitting diode chips includes a light emitting element, in the pixel region, a first light emitting element is adjacent to a second light emitting element in a first direction, a first light emitting element is adjacent to a third light emitting element in a second direction, a fourth light emitting element is adjacent to a fifth light emitting element in the first direction, a fourth light emitting element is adjacent to a sixth light emitting element in the second direction, a second light emitting element is adjacent to the fourth light emitting element in the first direction, the second direction crosses the first direction, the first to third light emitting elements emit light of the same color, and the fourth to sixth light emitting elements emit light of different colors from the first to third light emitting elements.

Effects of the invention

According to one embodiment of the present invention, a display device using a Micro LED having a large area for a display element can be realized. Further, according to one embodiment of the present invention, a display device including a display surface having a curved surface and using a Micro LED having a large area for a display element can be realized.

In addition, according to one embodiment of the present invention, the manufacturing cost of the display device using Micro LEDs for the display element can be reduced. In addition, according to one embodiment of the present invention, a display device using Micro LEDs for a display element can be manufactured with high yield.

Note that the description of these effects does not hinder the existence of other effects. Furthermore, one embodiment of the present invention does not require that all of the above effects be achieved. Effects other than the above-described effects are apparent from and can be extracted from the description of the specification, drawings, and claims.

Brief description of the drawings

Fig. 1A to 1C are examples of structural cross-sectional views showing an embodiment of the present invention.

Fig. 2A to 2D are examples of process cross-sectional views showing an embodiment of the present invention.

Fig. 3A is a plan view showing a pixel region before laser irradiation, and fig. 3B is an example of a perspective view of a part of the enlarged pixel region.

Fig. 4 is a plan view showing an example of an embodiment of the present invention.

Fig. 5A is a schematic view showing a part of a cross section of a display device according to an embodiment of the present invention, in which a curved surface is used as a display surface and Micro LEDs are used as display elements, and fig. 5B is a cross section of the display device.

Fig. 6A1 and 6B1 are perspective views illustrating a method of manufacturing a display device, and fig. 6A2 and 6B2 are cross-sectional views illustrating a method of manufacturing a display device.

Fig. 7A1 and 7B1 are perspective views illustrating a method of manufacturing a display device, and fig. 7A2 and 7B2 are cross-sectional views illustrating a method of manufacturing a display device.

Fig. 8A1 and 8B1 are perspective views illustrating a method of manufacturing a display device, and fig. 8A2 and 8B2 are cross-sectional views illustrating a method of manufacturing a display device.

Fig. 9A1 and 9B1 are perspective views illustrating a method of manufacturing a display device, and fig. 9A2 and 9B2 are cross-sectional views illustrating a method of manufacturing a display device.

Fig. 10A1 and 10B1 are perspective views illustrating a method of manufacturing a display device, and fig. 10A2 and 10B2 are cross-sectional views illustrating a method of manufacturing a display device.

Fig. 11 is a perspective view of the device.

Fig. 12 is a schematic diagram showing the structure of the apparatus.

Fig. 13A to 13C are sectional views illustrating a manufacturing method of the display device.

Fig. 14A to 14D are sectional views illustrating a manufacturing method of the display device.

Fig. 15 is a schematic view of a cross section of a display device as a modification example.

Fig. 16A to 16C are structural examples of the light-emitting element.

Fig. 17 is a diagram showing an example of a cross-sectional structure of the display device.

Fig. 18A is a block diagram showing an example of a display device. Fig. 18B to 18D are diagrams showing one example of a pixel circuit.

Fig. 19A to 19D are diagrams showing one example of a transistor.

Fig. 20 is a plan view showing a structural example of the display device.

Fig. 21A to 21D are diagrams showing examples of pixels. Fig. 21E and 21F are diagrams showing examples of circuit diagrams of pixels.

Fig. 22 is a diagram showing a structural example of the vehicle interior.

Fig. 23 is a diagram showing a structural example of the vehicle interior.

Fig. 24A and 24B are diagrams illustrating an embodiment of a light-emitting device.

Modes for carrying out the invention

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It is noted that the present invention is not limited to the following description, and one of ordinary skill in the art can easily understand the fact that the manner and details thereof can be changed into various forms. The present invention should not be construed as being limited to the following embodiments.

(embodiment 1)

In this embodiment mode, a structure in which a plurality of flexible substrates on which a plurality of light emitting diode chips are mounted are connected together and sealed with a substrate provided with a nitride film is described with reference to fig. 1.

Fig. 1A is a cross-sectional view of an end portion of a display device, in which a flexible substrate 800 having a plurality of light-emitting diode chips mounted thereon and a second substrate 801 having a plurality of light-emitting diode chips mounted thereon are arranged in an array, the periphery thereof is fixed by a resin 19, and the outer sides thereof are sandwiched between a third substrate 12a provided with a nitride film 18a and a fourth substrate 12b provided with a nitride film 18 b. When the nitride film 18a is deposited on the third substrate 12a, a sputtering method, a chemical vapor deposition (CVD: chemical Vapor Deposition) method, or a plasma enhanced chemical vapor deposition (PECVD: plasma Enhanced CVD) method may be used. Alternatively, the thin film may be formed by an atomic layer deposition (ALD: atomic Layer Deposition) method with less deposition damage. The nitride films 18a and 18b may be a nitride insulating film, an oxynitride insulating film, or an oxynitride insulating film, and examples thereof include a silicon nitride film, an aluminum nitride film, a silicon oxynitride film, an aluminum oxynitride film, a silicon oxynitride film, and an aluminum oxynitride film. The thickness of the nitride films 18a and 18b is preferably 1nm to 500 nm.

In the present specification, "oxynitride" refers to a material having a greater oxygen content than nitrogen content in its composition, and "nitride oxide" refers to a material having a greater nitrogen content than oxygen content in its composition. For example, "silicon oxynitride" refers to a material having a greater oxygen content than nitrogen content in its composition, and "silicon oxynitride" refers to a material having a greater nitrogen content than oxygen content in its composition.

In addition, a plurality of light emitting diode chips provided over the substrate 800 having flexibility and a plurality of light emitting diode chips provided over the second substrate 801 are arranged at equal intervals to constitute one pixel region.

The arrangement method of the substrate 800 having flexibility and the second substrate 801 will be described in detail in embodiment mode 2 below. Note that an end face of the substrate 800 having flexibility adjacent to the second substrate 801 is processed by laser.

Here, although the flexible substrate 800 is illustrated as a flat surface, when the flexible substrate 800 is fixed to a support having a curved surface, the flexible substrate 800 is preferably fixed in a state that the flexible substrate 800 is bent along the curved surface. At this time, the entire display device (including at least the substrate 800 having flexibility, the second substrate 801, the resin 19, the third substrate 12a, and the fourth substrate 12 b) is bent and fixed.

By adopting the above structure, moisture can be prevented from entering from the outside by the third substrate 12a provided with the nitride film 18a and the fourth substrate 12b provided with the nitride film 18b, and reliability of the display device can be improved.

The light emitting direction of the light emitting diode chip provided on the flexible substrate 800 is a direction perpendicular to the substrate surface (two light emitting directions opposite to each other across the substrate surface), and it is preferable that the resin 19 and the third substrate 12a on at least one path in the light emitting direction have light transmittance.

Further, the resin 19, which is a path overlapping in two light emission directions, that is, a path overlapping with a first light emission path through the third substrate 12a and a path overlapping with a second light emission path through the fourth substrate 12b, and the third substrate 12a and the fourth substrate 12b are each made of a material having light transmittance, whereby display of light emission in two directions can be performed. In addition, since the pixel region of the display device has light transmittance, the display device may be a so-called see-through display device.

Fig. 1B shows a modification of fig. 1A, which is different from fig. 1A in which two substrates are sealed, and is an example in which one substrate is folded and sealed. FIG. 1B is identical to FIG. 1A except that it is sealed by a substrate, so the same reference numerals are attached to the same parts as in FIG. 1A.

Since the sealing is performed by one substrate 12 instead of two substrates, the number of components can be reduced, and the manufacturing cost can be reduced. In addition, since it is sealed by one substrate 12, barrier properties are improved.

Fig. 1C shows an example different from fig. 1A and 1B. Fig. 1C shows an example in which an end portion of the substrate 810 having flexibility overlaps with an end portion of the second substrate 811. In addition, the folded one substrate 12 is selectively provided with a nitride film 18a and a nitride film 18b.

In fig. 1C, a plurality of light emitting diode chips provided over a flexible substrate 810 and a plurality of light emitting diode chips provided over a second substrate 811 are arranged at equal intervals to form one pixel region. The end face of the substrate 810 having flexibility is a face divided by a laser. The second substrate 811 includes an element layer, and the element layer and an end face of the second substrate 811 are also faces divided by laser light. By cutting the end portion of the substrate 810 with laser light before the substrate 810 having flexibility and the second substrate 811 are overlapped, a boundary between the substrate 810 having flexibility and the second substrate 811 can be made inconspicuous when the display device performs display.

In addition, an optical film may be separately provided. For example, when the light emitting diode chip is a light emitting element which emits ultraviolet light, a color conversion layer may be provided to realize a display device of full color display. The color conversion layer may be provided on the light path in the light emission direction, and when the light emission direction in two directions is adopted, two color conversion layers (or color conversion films) may be provided so as to sandwich the light emitting diode chip from the up-down direction. Because alignment is important, a color conversion layer (or a color conversion film) is preferably provided between the substrate 810 having flexibility and the resin 19. In addition, a display device for full-color display can be realized by providing a color filter using a white light emitting diode chip.

In addition, a circular polarizing film may be provided as the optical film. In the case of providing a circular polarizing film, it is preferable to provide the circular polarizing film on one surface of one substrate 12 to be folded. By providing the circular polarizing film, the boundary between the substrate 810 having flexibility and the second substrate 811 can be made inconspicuous when the display device performs display.

At least a part of this embodiment can be implemented in combination with other embodiments described in this specification as appropriate.

(embodiment 2)

In this embodiment, a display device and a method for manufacturing the same according to one embodiment of the present invention will be described.

First, fig. 4, 5A, and 5B show examples of display devices that can be manufactured by the method for manufacturing a display device according to one embodiment of the present invention. Fig. 4 shows an example of a top view of a display device in which two pixel regions formed over two flexible substrates (a substrate 800 and a second substrate 801) with a laser irradiation line 700 as a boundary are arranged.

Although fig. 4 shows a plan view, the display device may be fixed to a curved surface as shown in fig. 5A and 5B.

In the display device shown in fig. 5A, a substrate 800 having flexibility is fixed to a support 10 having a curved surface through a resin 19. A pixel region is formed over the flexible substrate 800, and a light-emitting element 17R, a light-emitting element 17G, and a light-emitting element 17B are provided over the pixel region. The arrangement of the light emitting elements 17R, 17G, and 17B may be stripe type, mosaic type, or Delta type. Further, a white light emitting element may be added to arrange light emitting elements of four colors.

The light emitting elements 17R, 17G, and 17B are Micro LED chips that emit light of different colors, and a wiring layer is provided between the Micro LED chips and the flexible substrate 800. The wiring layer includes an electrode 21 and an electrode 23 connected to each of the light emitting elements 17R, 17G, and 17B.

Examples of the substrate 800 having flexibility include the following materials: acrylic resin, polyester resin typified by PET or PEN, polyacrylonitrile resin, polyimide resin, polymethyl methacrylate resin, PC resin, PES resin, polyamide resin (nylon, aramid), polysiloxane resin, polycycloolefin resin, polystyrene resin, polyamide-imide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, PTFE resin, ABS resin. Particularly, a material having a low linear expansion coefficient is preferably used, and for example, a polyamide-imide resin, a polyimide resin, a polyamide resin, or PET is preferably used. In addition, a substrate in which a fibrous body is impregnated with a resin and a substrate in which an inorganic filler is mixed with a resin to reduce the linear expansion coefficient may be used.

Alternatively, a metal thin film may be used as the substrate 800 having flexibility. As the metal thin film, stainless steel or aluminum can be used. When a metal thin film is used, durability can be achieved even when the thermal temperature at the time of mounting Micro LED chips is high.

The substrate 800 having flexibility is preferably provided with a circuit for driving the light emitting diode chip 17. In the substrate 800 having flexibility, a circuit is formed of, for example, a transistor, a capacitor, a wiring, and an electrode. More preferably, the light emitting element 17R, the light emitting element 17G, and the light emitting element 17B each adopt an active matrix system in which one or more transistors are connected. In the pixel region, the transistor is electrically connected to the electrode 21 and the electrode 23.

Note that although fig. 5A shows an example in which the light emitting element 17R, the light emitting element 17G, and the light emitting element 17B are all electrically connected to two electrodes, that is, the electrode 21 and the electrode 23, one embodiment of the present invention is not limited thereto. The electrodes electrically connected to the pixel circuit may be formed in accordance with the number of electrodes included in the light-emitting elements 17R, 17G, and 17B. In this embodiment, the light-emitting elements 17R, 17G, and 17B are shown as one of the constituent elements provided over the flexible substrate 800, but the light-emitting elements may be replaced by light-emitting devices. Similarly, the capacitor may be replaced with a capacitor device.

Fig. 5B shows an example of a cross-sectional view of the light-emitting device when the light is emitted. Note that fig. 5A corresponds to a diagram of the region 15 surrounded by a broken line in fig. 5B enlarged. By arranging a flexible substrate having one pixel region formed on the support 10 and disposing the substrate in a spliced manner, a large area of the display surface can be achieved. In fig. 5B, four light emitting panels are fixed with resin 19. For example, a portion where a pixel region is formed by mounting red light emitting elements, green light emitting elements, and blue light emitting elements in a matrix on one flexible substrate is used as the light emitting panel 16a, so that a full-color display device is obtained. In addition, a light-emitting panel 16b adjacent to the light-emitting panel 16a, a light-emitting panel 16c adjacent to the light-emitting panel 16b, and a light-emitting panel 16d adjacent to the light-emitting panel 16c are shown. In addition, by providing the cover material 13 covering the four light emitting panels, the boundaries of the pixel areas are made inconspicuous. The cover material 13 may not be provided if not required. The support body 10 may be also referred to as a frame or a support member, and at least a part of the support body has a curved surface. When the display device is provided in the vehicle interior, the support body 10 is plastic, metal, glass, or rubber. The support 10 is not particularly limited, and may be a member at least a part of which has a curved surface. The support 10 may be provided with a wiring layer, and the wiring included in the wiring layer may be electrically connected to the electrode of the light-emitting panel. The wiring layer may also include a wiring, an insulating film covering the wiring, and an electrode connected to the wiring through an opening provided in the insulating film. The wiring included in the wiring layer is used as an auxiliary wiring, a connection wiring, a power supply line, a signal line, or a fixed potential line. The wiring of the wiring layer may be formed on the support body 10 having a curved surface by a known technique. For example, the wiring layer may be provided on the support 10 by a method of selectively forming silver paste, a transposition method, or a transfer method.

Next, a method for manufacturing a display device in which pixel regions are arranged in an array over two flexible substrates will be described with reference to fig. 2.

Fig. 2A is a schematic sectional view of a stage in which laser light is irradiated to an end portion of a substrate 800 having flexibility after a light emitting diode chip is mounted thereon. The flexible substrate 800 has an element layer 820 including an electrode or a transistor formed thereon in advance, and a plurality of light emitting diode chips are arranged in a matrix at equal intervals. From the viewpoint of processing, it is difficult to provide the element layer 820 or the light emitting diode chip in the peripheral portion of one substrate 800 having flexibility, and the peripheral portion has a region where no element is formed. Then, a part of the element layer 820 (an end portion of the pixel region) is cut off by the laser irradiation line 700 with respect to the element layer 820 by irradiating the laser. In addition, a part of the substrate 800 having flexibility is cut off so as to be offset in parallel with the laser irradiation line 700 with respect to the element layer 820. Here, the element layer 820 has a structure not including an LED, but the structure of the element layer 820 is not particularly limited, and may be referred to as an element layer 820 including an LED.

Fig. 2B shows a state after irradiation. Then, the irradiation position of the laser light is controlled in depth to perform scanning, and a part of the irradiation position is removed as shown in fig. 2C, and a convex portion protruding from a part of the flexible substrate 800 is formed on the end surface thereof.

Then, the other substrate (second substrate 801) is also irradiated with laser light, and the positions of the laser light irradiation line with respect to the element layer 821 and the laser light irradiation line with respect to the end face of the second substrate 801 are shifted, so that a recess is formed in the end face of the second substrate 801.

Then, as shown in fig. 2D, the substrate 800 having flexibility as a first substrate and the second substrate 801 are combined, whereby the light emitting diode chips can be arranged at equal intervals in one direction. The top view at this stage corresponds to fig. 4.

By fitting the convex portion of the flexible substrate 800 and the concave portion of the second substrate 801, the adhesive surface is increased and fixation is facilitated. In addition, even in the case where the interval between the light emitting diode chips is narrow, the light emitting diode chips may be fixed in such a manner that they are regularly arranged at equal intervals in one direction. Accordingly, a display device with a large area can be manufactured. The element layer 821 provided over the second substrate 801 may be electrically connected to a wiring or an electrode included in the element layer 821 and a wiring or an electrode included in the element layer 820 provided over the substrate 800 having flexibility.

The top view of the display device before laser irradiation corresponds to fig. 3A. In the display device shown in fig. 3A, a pixel region 702, a source driver circuit portion 706, and a gate driver circuit portion 704 are provided over a flexible substrate 801 which is a first substrate. The element layer provided over the substrate 800 having flexibility may be provided with the pixel region 702, the source driver circuit portion 706, and the gate driver circuit portion 704 thereof. The source driver circuit portion 706 and the gate driver circuit portion 704 may be mounted as driver ICs. In addition, as shown in fig. 3B, a plurality of light emitting diode chips 17 are provided on the pixel region 702. The plurality of light emitting diode chips 17 are three or four light emitting elements, and are arranged so as to realize a full-color display device. The light emitting diode chip 17 is connected to the electrodes 21 and 23 of the element layer.

Next, a method for manufacturing each display device will be described with reference to fig. 6A1 to 14D. Fig. 6A1 to 14D are a perspective view and a cross-sectional view of each stage in the process of the manufacturing method of the display device.

The emission color of the LED chip that can be used in the method for manufacturing a display device according to one embodiment of the present invention is not particularly limited. For example, an LED chip that emits white light may also be used. For example, the present invention can be applied to an LED chip that emits light in the wavelength region of visible rays of red, green, and blue. For example, the present invention can be applied to an LED chip that emits light in the wavelength range of near infrared, and ultraviolet. In the case of using an LED chip that emits light in the wavelength region of near infrared rays, ultraviolet rays, only one type of LED chip is arranged, and a color conversion layer or a color conversion film is provided overlapping on the LED chip. In this structure, there is little step on the surface of the display device in the vicinity of the boundary between the substrate 800 having flexibility and the second substrate 801, so that there is no roughness on the surface of the color conversion layer or the color conversion film when the color conversion layer or the color conversion film is overlapped, and thus it is preferable.

In this embodiment mode, a Micro LED having a double heterojunction is described. Note that the light emitting diode is not particularly limited, and for example, a Micro LED having a quantum well junction, an LED using a nanopillar, may be employed.

The area of the light-emitting region of the light-emitting diode is preferably 1mm ² Hereinafter, more preferably 10000. Mu.m ² Hereinafter, it is more preferably 3000. Mu.m ² Hereinafter, it is more preferably 700. Mu.m ² The following is given. The area of the region is preferably 1. Mu.m ² The above is more preferably 10. Mu.m ² The above is more preferably 100. Mu.m ² The above.

Note that the LED that can be used for the display device of one embodiment of the present invention is not limited to the Micro LED described above. For example, an area of the light-emitting region larger than 10000 μm can also be used ² Is also referred to as Mini LED). The Mini LED is a light emitting diode having a rectangular planar shape and a chip size of 0.1mm or more on at least one side.

The display device of this embodiment mode preferably includes a transistor having a metal oxide layer in a channel formation region. Transistors using metal oxide layers can reduce power consumption. Thus, by combining the transistor with the Micro LED, a display device with extremely low power consumption can be realized. Micro LEDs refer to light emitting diodes having a rectangular planar shape with at least one side smaller than a chip size of 0.1 mm.

A plurality of LED chips are formed on an LED chip substrate. Fig. 6A1 and 6A2 show an example of the LED chip substrate 900. Fig. 6A1 is a perspective view of the LED chip substrate 900, and fig. 6A2 is a cross-sectional view along the dash-dot line X1-X2 shown in fig. 6 A1. As the LED chip, a semiconductor layer 81 including an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer, an electrode 85 serving as a cathode, and an electrode 87 serving as an anode are formed over a substrate 71A. A plurality of LED chips are formed on the LED chip substrate 900, and the LED chip substrate 900 is separated along the LED chip region 51A, whereby a plurality of LED chips can be manufactured.

The substrate 71A of the LED chip substrate 900 is polished, whereby the substrate 71A is thinned to a desired thickness (fig. 6B1 and 6B 2). By reducing the thickness of the substrate 71A, it is easy to separate the LED chips. Alternatively, the substrate 71A may be removed from the LED chip substrate 900 by laser irradiation without polishing.

The polishing will be described in detail. First, the electrode 85 and the electrode 87 of the LED chip substrate 900 are attached to the flat plate 903. The LED chip substrate 900 and the flat plate 903 bonded together are placed on a table 905. At this time, the flat plate 903 side is brought into contact with the table 905, and the LED chip substrate 900 and the flat plate 903 are fixed to the table 905 using a vacuum chuck. Next, the table 905 is rotated in the plane of the table 905, and a grindstone 907 provided in the grindstone 909 is brought into contact with the substrate 71A, whereby the substrate 71A is ground into a substrate 71. When polishing is performed, the grinding wheel 909 and the grinding stone 907 may be rotated.

Next, the surface of the substrate 71 is preferably polished with a polishing agent (also referred to as slurry) to planarize the surface (fig. 7A1 and 7 A2). By flattening the surface of the substrate 71, a reduction in yield in the subsequent steps can be suppressed.

In addition, when polishing and lapping are preferably performed, a film 901 for protection is provided on the electrode 85 and electrode 87 side and is fixed, and then polishing is performed (see fig. 6B 2). The film 901 is removed after polishing.

Next, a first film 919 is provided on the electrode 85 and electrode 87 side, and the LED chip substrate 900 and the first film 919 are fixed to a first fixing tool 921 (fig. 7B1 and 7B 2). As the first film 919, a film having a property of being stretched when pulled up (also referred to as an expanded film) is preferably used. As the first film 919, a vinyl chloride resin, a silicone resin, a polyolefin resin can be used. In addition, it is preferable that an adhesive agent having a property that its adhesiveness becomes weak when light is irradiated is provided on the surface of the first film 919. Specifically, as the first film 919, a film whose adhesiveness is weakened when irradiated with ultraviolet light can be suitably used. As the first fixing tool 921, for example, a ring-shaped jig as shown in fig. 7B1 can be suitably used.

Next, a dividing line 911 is formed along the LED chip region 51A of the LED chip substrate 900 (fig. 8A1 and 8 A2). The dividing line 911 may be formed using a mechanical dicing method (machine scribing method). The mechanical dicing method is as follows: the scribing tool is pressed against the substrate 71, whereby grooves (also called scribe lines, score lines) are mechanically formed in the substrate 71. As the scribing tool, a diamond blade may be used.

The dividing line 911 may be formed by a laser dicing method. The laser scribing method comprises the following steps: after the substrate 71 is locally heated by irradiation with laser light, the substrate is rapidly cooled, and a thermal stress generated at this time causes a modified layer to be formed in the substrate 71, thereby forming a dividing line 911. In the laser dicing method, the dividing line 911 may be formed on the surface of the substrate 71 or may be formed inside the surface of the substrate 71. Mechanical scribing requires replacement of the scribing tool due to wear of the scribing tool, and laser scribing does not require replacement of the scribing tool.

In addition, the substrate 71 may be cut along the LED chip region 51A by a blade dicing method. In the blade cutting method, a cutting edge (also referred to as a blade) is rotated at a high speed to form a cut in an object, and diamond is used as the cutting edge. When the blade dicing method is used, half-cut (half-cut) may be used, that is, the substrate 71 may be cut to the halfway in the thickness direction thereof, or full-cut (full-cut) may be used, that is, the substrate 71 and the semiconductor layer 81 may be completely cut in the thickness direction thereof.

Next, the LED chip substrate 900 is divided into LED chips. When dividing into LED chips, the LED chip substrate 900 may be divided into LED chips by, for example, the following method: the LED chip substrate 900 is mounted on a support table 913 having an opening 914, and then a blade 915 is struck on the LED chip substrate 900 along a dividing line 911 (fig. 8B1 and 8B 2). Alternatively, the LED chips may be separated by sandwiching the LED chip substrate 900 with rollers and providing the rollers with surfaces having different inclination angles. In addition, when dividing into LED chips, a sheet 923 (also referred to as a dividing sheet) for protection purposes may be provided on the substrate 71 side, and then the LED chips may be divided. Fig. 9A1 and 9A2 show the LED chip substrate 900 after being divided into LED chips.

Next, the first film 919 is pulled up to separate the LED chips 51 from each other, thereby expanding the interval between the LED chips 51 (fig. 9B1 and 9B 2). By expanding the interval between the LED chips 51, the subsequent processing is easy. When separating the LED chips 51, for example, each LED chip 51 may be separated by pushing up the flat plate 924 having an area larger than the area where the LED chip 51 is disposed from the first film 919 side toward the LED chip 51 side, and the first film 919 is pulled up.

Next, the second film 927 is fixed to the second fixing tool 925, and the second film 927 and the second fixing tool 925 are provided to the substrate 71 side (fig. 10A1 and 10 A2).

Note that, when the LED chips 51 that have been separated are used, the display device may be manufactured from the steps shown in fig. 10A1 and 10 A2. By providing the second film 927 on the substrate 71 side of the separated LED chip 51 and fixing the second film 927 to the second fixing tool 925, a process described later can be entered. In this case, as shown in fig. 10A1 and 10A2, it is preferable to provide a space between the LED chips 51, and the accuracy of the subsequent mounting process is improved, so that the display device can be manufactured with high yield. In addition, by disposing the plurality of LED chips 51 in a matrix in the second film 927, the manufacturing cost of the subsequent mounting process can be reduced.

Next, ultraviolet rays are irradiated from the first film 919 side, whereby the first film 919 and the first fixing tool 921 are separated from the LED chip 51 (fig. 10B1 and 10B 2). In the step of separating the LED chips, the first film 919 may be stretched and bent. By separating and re-fixing the LED chip 51 from the first film 919 to the second film 927, the deflection of the second film 927 can be reduced. By reducing the deflection of the second film 927, the accuracy of the subsequent mounting process can be improved, and a display device can be manufactured with high yield.

As the second film 927, a film having elasticity is preferably used. The elastic membrane is deformed by the application of force and returns to its original shape by removal of the force. As the second film 927, a film having a high tensile elastic modulus can be suitably used. As the second film 927, a polyamide resin, a polyimide resin, or a polyethylene naphthalate resin can be used. Further, the second film 927 preferably has high heat resistance. In addition, an adhesive is provided on the surface of the second film 927, so that the LED chip substrate 900 can be fixed on the second film 927. As the second fixing tool 925, for example, an annular jig as shown in fig. 10B1 can be suitably used.

Here, the LED chip 51 is preferably inspected. As the inspection of the LED chip 51, an appearance inspection may be used. Further, a voltage may be applied between the electrode 85 and the electrode 87, so that the light emission state from the LED chip 51 may be checked. The position information in the second film 927 of the LED chip 51 determined to be defective in the inspection is preferably acquired. By acquiring the positional information of the defective product, the defective product can be removed from the mounting object in the subsequent mounting process.

Next, a method of mounting the LED chip 51 on the substrate 800 having flexibility using a conductive paste such as solder is described.

Fig. 11 and 12 show an example of an apparatus 950 that can be used for a process of mounting the LED chip 51 on the substrate 800 having flexibility. Fig. 11 is a perspective view of the device 950, and fig. 12 is a schematic view showing the structure of the device 950. The apparatus 950 includes a stage 951, a single-axis robot 953 for the X axis, a single-axis robot 955 for the Y axis, a holding mechanism 959, a push-out mechanism 929, and a control device 961.

The stage 951 has a function of fixing the substrate 800 having flexibility. The substrate 800 having flexibility may be fixed using, for example, a vacuum suction mechanism. The stage 951 can be moved in the X direction and the Y direction by the single-axis robot 953 and the single-axis robot 955 on a plane parallel to the surface of the substrate 800 having flexibility.

The holding mechanism 959 holds a second fixing tool 925 for fixing the LED chip 51 and the second film 927. The holding mechanism 959 has a function of moving the second fixing tool 925 for fixing the LED chip 51 and the second film 927 to an arbitrary position.

The push-out mechanism 929 has a function of moving up and down and disposing the LED chip 51 on the substrate 800 having flexibility. The push-out mechanism 929 has a column shape (including a cylindrical shape and a polygonal column shape), and may have a thin shape on a side contacting the LED chip 51. The diameter of the tip of the push-out mechanism 929 contacting the LED chip 51 is preferably smaller than the width of the LED chip 51.

The control device 961 has a function of controlling the single-axis robot 953, the single-axis robot 955, the gripping mechanism 959, and the push-out mechanism 929. The positional information of the LED chip determined to be a defective product in the previous step of inspecting the LED chip 51 is input to the control device 961. By inputting the position information of the defective product into the control device 961, the defective product can be excluded from the installation object.

An alignment mechanism for camera 957 is preferably provided in device 950. The position of the second fixture 925 is controlled with reference to alignment marks provided on the substrate 800 having flexibility.

A method of mounting the LED chip 51 on the substrate 800 having flexibility is described in detail with reference to fig. 13 and 14.

First, the plurality of LED chips 51 fixed to the second film 927 are opposed to the substrate 800 having flexibility. When the LED chips 51 are placed in opposition, it is preferable to acquire positional information of the LED chips 51 by detecting the outline of the LED chips 51 with the camera 957. The positions of the electrodes 85 and 87 of the LED chip 51 and the positions of the electrodes 21 and 23 on the flexible substrate 800 are aligned by adjusting the positions of the LED chip 51 by the holding mechanism 959 based on the positional information of the LED chip 51 (fig. 13A). The holding mechanism 959 is preferably movable in the X direction, the Y direction, and the θ direction on a plane parallel to the surface of the substrate 800 having flexibility. By moving in the X direction, the Y direction, and the θ direction, the positions of the electrode 85 and the electrode 87 of the LED chip 51 and the positions of the electrode 21 and the electrode 23 on the substrate 800 having flexibility can be aligned with high accuracy.

Note that although fig. 12 shows a configuration in which the camera 957 is disposed above the second film 927 to detect the positions of the electrodes 85 and 87 of the LED chip 51 from above the second film 927, one embodiment of the present invention is not limited to this, and a camera (not shown) may be provided below the flexible substrate 800 to detect the positions of the electrodes 85 and 87 of the LED chip 51 and the positions of the electrodes 21 and 23 on the flexible substrate 800 from below the flexible substrate 800.

Then, the pushing mechanism 929 is pushed out from the second film 927 side toward the flexible substrate 800, and the electrode 85 and the electrode 87 are brought into contact with the electrode 21 and the electrode 23, respectively. Then, ultrasonic waves are applied to the push-out mechanism 929, whereby the electrodes 85 and 87 are respectively pressed against the electrodes 21 and 23 (fig. 13B). The pushing mechanism 929 may be heated to thermally press the electrodes 85 and 87 to the electrodes 21 and 23, respectively. Alternatively, they may be bonded by ultrasonic waves and heat. When the pushing mechanism 929 is heated, the temperature of the pushing mechanism 929 is preferably equal to or lower than the heat resistant temperature of the second film 927. By setting the temperature of the push-out mechanism 929 to be equal to or lower than the heat resistant temperature of the second film 927, the second film 927 can be prevented from being deformed and deflected.

The push-out mechanism 929 is connected to a unit 963 shown in fig. 12. The unit 963 includes an ultrasonic oscillator and can apply ultrasonic waves to the push-out mechanism 929. The unit 963 includes a heating mechanism, and can heat the push-out mechanism 929. The unit 963 may include an ultrasonic oscillator and a heating mechanism, and may apply ultrasonic waves to the push-out mechanism 929 to heat the same. The unit 963 is connected to a control device 961, and the control device 961 controls the timing of application and heating of ultrasonic waves.

Further, conductive bumps may be provided on the electrodes 21 and 23, and the LED chip 51 may be brought into contact with the bumps.

Next, the push-out mechanism 929 is separated from the second film 927 (fig. 13C). The electrodes 85 and 87 are respectively pressed against the electrodes 21 and 23, whereby the LED chips 51 mounted on the electrodes 21 and 23 are separated from the second film 927. The adhesion of the adhesive provided on the surface of the second film 927 is preferably smaller than the pressing force of the electrode 85 and the electrode 21, and the electrode 87 and the electrode 23. By using an adhesive whose adhesiveness is smaller than the pressing force for the second film 927, the LED chip 51 can be efficiently mounted to the substrate 800 having flexibility, and the manufacturing cost of the display device can be reduced.

Here, when the second film 927 is bent, it is difficult to align the positions of the electrodes 85 and 87 of the LED chip 51 and the electrodes 21 and 23 on the flexible substrate 800, and conduction failure between the electrodes 85 and 87 and the electrodes 21 and 23 may occur. In one embodiment of the present invention, the second film 927 has elasticity, and the second film 927 can be restored to the original shape when the push-out mechanism 929 is separated from the second film 927. Since the second film 927 is restored to the original shape, the deflection of the second film 927 can be suppressed, and the positions of the electrode 85 and the electrode 87 and the positions of the electrode 21 and the electrode 23 can be aligned with high accuracy. The tensile elastic modulus of the second film 927 is preferably 3GPa to 18GPa, more preferably 5GPa to 16GPa, still more preferably 7GPa to 14 GPa. By setting the tensile elastic modulus of the second film 927 to be within the above range, the second film 927 can be stretched appropriately when the LED chip 51 is brought into contact with the electrodes 21 and 23, and deflection of the second film 927 can be reduced when the position of the LED chip 51 is aligned, so that a display device can be manufactured with high yield and manufacturing cost can be reduced.

Next, the LED chip 51 fixed to the second film 927 is aligned with the positions of the electrode 21 and the electrode 23 where the LED chip 51 is not provided (fig. 14A). When alignment is performed, any one or more of the stage 951, the clamp mechanism 959, and the push-out mechanism 929 may be moved. More preferably, any two or more of the stage 951, the holding mechanism 959, and the push-out mechanism 929 are moved. By moving two or more of the stage 951, the holding mechanism 959, and the push-out mechanism 929, accuracy in aligning the electrodes 85 and 87 of the LED chip 51 with the electrodes 21 and 23 on the flexible substrate 800 can be improved.

Next, the pushing mechanism 929 is pushed out from the second film 927 side toward the flexible substrate 800, and the electrode 85 and the electrode 87 are brought into contact with the electrode 21 and the electrode 23, respectively. Next, the electrode 85 and the electrode 87 are respectively pressed against the electrode 21 and the electrode 23 (fig. 14B). Subsequently, the push-out mechanism 929 is moved onto the second film 927. Thereby, the LED chip 51 mounted on the electrode 21 and the electrode 23 is separated from the second film 927 (fig. 14C).

By repeating the above operation, the LED chip is mounted on the entire pixel region of the substrate 800 having flexibility. In addition, the LED chip 51B determined as a defective product in the inspection process of the LED chip 51 is not mounted on the substrate 800 having flexibility because its positional information is input in the control device 961 (fig. 14C and 14D). By inputting positional information of the LED chips of defective products into the control device 961, only the LED chips 51 of good quality can be mounted on the substrate 800 having flexibility. After the mounting, a step of dissolving the solder by reflow under a nitrogen atmosphere to produce an alloy may be added.

In the method for manufacturing a display device according to one embodiment of the present invention, a plurality of types of LED chips 51 that emit colors in different wavelength regions may be provided over the flexible substrate 800. For example, a case will be described in which the LED chip 51 that emits light in the red wavelength region (hereinafter, referred to as red light), the LED chip 51 that emits light in the green wavelength region (hereinafter, referred to as green light), and the LED chip 51 that emits light in the blue wavelength region (hereinafter, referred to as blue light) are provided on the substrate 800 having flexibility. The LED chips 51 are mounted on the substrate 800 having flexibility using the second film 927 to which the plurality of LED chips 51 emitting red light are fixed and the second fixing tool 925. Next, the LED chips 51 are mounted on the substrate 800 having flexibility using the second film 927 to which the plurality of LED chips 51 emitting green light are fixed and the second fixing tool 925. Next, the LED chips 51 are mounted on the substrate 800 having flexibility using the second film 927 to which the plurality of LED chips 51 emitting blue light are fixed and the second fixing tool 925. Thus, the LED chip 51 emitting red light, the LED chip 51 emitting green light, and the LED chip 51 emitting blue light may be provided on the substrate 800 having flexibility. Note that the order of the kinds of the mounted LED chips is not particularly limited.

Note that although an example in which the LED chips 51 are mounted from one set of the second film 927 and the second fixing tool 925 to the substrate 800 having flexibility is shown, one embodiment of the present invention is not limited thereto, and a structure in which the LED chips 51 are mounted from a plurality of sets of the second film 927 and the second fixing tool 925 may be adopted. By adopting this structure, a display device can be manufactured with high productivity. When the LED chip 51 emits light in a single color, the LED chip 51 is used as a sub-pixel, one pixel is configured by disposing a plurality of LED chips 51, and a pixel region is configured by disposing the pixels in a matrix. When the LED chip 51 includes a plurality of light emitting elements, the plurality of light emitting elements are used as sub-pixels, and one LED chip 51 constitutes a pixel.

Although the present embodiment shows an example in which the push-out mechanism 929 is used, the present embodiment is not limited to this, and a device in which an LED chip is mounted on the entire surface of a pixel region of the flexible substrate 800 by laser ablation through selective laser irradiation may be used.

Then, in order to adhere the substrate 800 having flexibility on which the LED chip is mounted over the entire surface of the pixel region, it is fixed to a support having a curved surface using the resin 19, whereby a display device can be obtained.

In order to increase the area, a display device having a single display surface in which pixel regions in m (m is a natural number of 2 or more) rows and n (n is a natural number of 1 or more) columns are arranged by a plurality of substrates 800 can be manufactured.

The above is a description of a method of manufacturing a display device.

Although fig. 5B shows an example in which a light emitting panel is provided on the convex side of the support body 10 having a curved surface, the structure is not particularly limited. Fig. 15 shows a modified example of the structure of fig. 5B.

In the display device of fig. 15, the fifth light-emitting panel 16e, the sixth light-emitting panel 16f, the seventh light-emitting panel 16g, and the eighth light-emitting panel 16h are arranged and fixed to the concave side of the support 11. Note that although the designation of the fifth light-emitting panel 16e is used herein so as not to be confused with fig. 5B, it is substantially equivalent to the first light-emitting panel. In the display device shown in fig. 15, the material of the cover material 13 preferably has light transmittance. The support 11 has a curved surface. The light emission direction 14B of the fifth light emission panel 16e is a direction different from that of fig. 5B.

Although the support having a constant radius of curvature is described with reference to fig. 5A, 5B, and 15, the structure is not particularly limited, and a structure in which a part of the support is flat along a member structure in the vehicle (an inner portion of an instrument panel, a ceiling, a pillar, window glass, a steering wheel, a seat, or a door) may be adopted, or a structure in which a convex portion shape and a concave portion shape are mixed may be adopted, instead of a structure in which the entire surface is a curved surface. For example, the display device according to one embodiment of the present invention may be provided on an inner wall of an automobile, specifically, an instrument panel, a ceiling, or a wall. The display device according to one embodiment of the present invention can realize a display surface having a large display area, and thus can display a map having a large area, and can be used not only as an automobile but also as a navigation device for a vehicle (an airplane or a submarine).

When the display surface is provided with a touch sensor, the display device has a display surface that can be touched by a finger of a driver. Accordingly, the display device including the touch sensor may also be referred to as a vehicle operation device.

Substrates having flexibility are susceptible to injury as compared to glass substrates. In particular, when a portable information terminal that performs an input operation by touching or approaching with a finger is provided with a touch panel, it is preferable to provide the information terminal with a surface protective film to prevent adhesion of dirt (sebum) and scratch of fingernails.

Since a display device provided in a vehicle is also touched or approached with a finger to perform an input operation, a protective film having excellent scratch resistance is preferably provided on the outermost surface of the display device. As the protective film, a silicon oxide film having optically good characteristics (high visible light transmittance or high infrared light transmittance) is used. By providing a protective film, the film can be prevented from being injured or stained. Further, DLC (diamond-like carbon), alumina (AlOx), a polyester material, or a polycarbonate material may be used as the protective film. The protective film is preferably a material having high transmittance to visible light and high hardness.

In addition, when the protective film is formed by a coating method, the protective film may be formed before the display device is fixed to the support having a curved surface or after the display device is fixed to the support having a curved surface.

As described above, by adopting the configuration of one embodiment of the present invention, a display device having high display quality can be provided. In addition, by adopting the configuration of one embodiment of the present invention, the degree of freedom in design of the display device is improved, and the design of the display device can be improved.

At least a part of this embodiment can be implemented in combination with other embodiments described in this specification as appropriate.

Embodiment 3

In this embodiment, the structure of the LED chip 51 shown in embodiment 2 will be described. The LED chip 51 is sometimes also referred to as a light emitting diode chip.

The LED chip includes a light emitting diode. The structure of the light emitting diode is not particularly limited, and MIS (Metal Insulator Semiconductor, metal-insulator-semiconductor) junction may be employed, and a homojunction structure, a heterojunction structure, or a double heterojunction structure having a PN junction or a PIN junction may be used. In addition, a superlattice structure, a single quantum well structure in which thin films that produce quantum effects are stacked, or a multiple quantum well (MQW: multi Quantum Well) structure may also be employed. In addition, an LED chip using a nano-pillar may be employed.

Fig. 16A and 16B show examples of LED chips. Fig. 16A shows a cross-sectional view of the LED chip 51, and fig. 16B shows a top view of the LED chip 51. The LED chip 51 includes a semiconductor layer 81. The semiconductor layer 81 includes an n-type semiconductor layer 75, a light emitting layer 77 on the n-type semiconductor layer 75, and a p-type semiconductor layer 79 on the light emitting layer 77. As a material of the p-type semiconductor layer 79, a material which has a band gap energy larger than that of the light-emitting layer 77 and which can enclose carriers in the light-emitting layer 77 can be used. In the LED chip 51, an electrode 85 serving as a cathode is provided on the n-type semiconductor layer 75, an electrode 83 serving as a contact electrode is provided on the p-type semiconductor layer 79, and an electrode 87 serving as an anode is provided on the electrode 83. In addition, the top surface and the side surface of the electrode 83 are preferably covered with an insulating layer 89. The insulating layer 89 is used as a protective film for the LED chip 51.

Fig. 16C shows an example of an enlarged view of the semiconductor layer 81. As shown in fig. 16C, the n-type semiconductor layer 75 may include an n-type contact layer 75a on the substrate 71 side and an n-type clad layer 75b on the light-emitting layer 77 side. The p-type semiconductor layer 79 may include a p-type clad layer 79a on the light emitting layer 77 side and a p-type contact layer 79b on the p-type clad layer 79 a.

The light emitting layer 77 may have a Multiple Quantum Well (MQW) structure in which a barrier layer 77a and a well layer 77b are stacked multiple times. The barrier layer 77a is preferably made of a material having a band gap energy larger than that of the well layer 77 b. By adopting the above structure, energy can be enclosed in the well layer 77b, so that quantum efficiency is improved and light emitting efficiency of the LED chip 51 can be improved.

In the face up (face up) LED chip 51, the electrode 83 may be made of a material that transmits light, for example, ITO (In ₂ O ₃ -SnO ₂ )、AZO(Al ₂ O ₃ -ZnO), in-Zn oxide (In ₂ O ₃ -ZnO)、GZO(GeO ₂ -ZnO)、ICO(In ₂ O ₃ -CeO ₂ ). In the face-up type LED chip 51, light is mainly emitted to the electrode 87 side. In the face down (face down) LED chip 51, a material that reflects light, for example, silver, aluminum, or rhodium may be used for the electrode 83. In the face-down type LED chip 51, light is mainly emitted to the substrate 71 side.

As the substrate 71, a sapphire single crystal (Al ₂ O ₃ ) Spinel single crystal (MgAl) ₂ O ₄ ) ZnO single crystal and LiAlO ₂ Single crystal, liGaO ₂ Oxide single crystal typified by single crystal or MgO single crystal, si single crystal, siC single crystal, gaAs single crystal, alN single crystal, gaN single crystal, zrB single crystal, or the like ₂ Is a representative boride single crystal. In the face-down type LED chip 51, the substrate 71 is preferably made of a material that transmits light, and for example, a sapphire single crystal that transmits light may be used.

A buffer layer (not shown) may be provided between the substrate 71 and the n-type semiconductor layer 75. The buffer layer has a function of relaxing the difference in lattice constant between the substrate 71 and the n-type semiconductor layer 75.

The LED chip 51 that can be used for the light emitting diode chip 17 preferably has a horizontal structure in which the electrode 85 and the electrode 87 are provided on the same surface side as shown in fig. 16A. By providing the electrode 85 and the electrode 87 of the LED chip 51 on the same surface side, the electrode 21 and the electrode 23 can be easily connected, and the structures of the electrode 21 and the electrode 23 can be simplified. The LED chip 51 that can be used as the light emitting diode chip 17 is preferably a face-down type. By using the face-down type LED chip 51, light emitted from the LED chip 51 is efficiently emitted to the display surface side of the display device, whereby a display device with high luminance can be realized. As the LED chip 51, a commercially available LED chip may be used.

The phosphor layer is used when white light emission is obtained. As the phosphor included in the phosphor layer, an organic resin layer having a phosphor printed or coated on the surface thereof, or an organic resin layer mixed with a phosphor can be used. The phosphor layer may be made of a material that is excited by light emitted from the LED chip 51 and emits light of a complementary color to the emission color of the LED chip 51. By adopting the above-described structure, the light emitted from the light emitting diode chip 17 is combined with the light emitted from the phosphor, so that white light can be emitted from the phosphor layer.

For example, by using the LED chip 51 that emits blue light and a phosphor that emits yellow light of a complementary color to the blue light, a structure in which white light is emitted from the phosphor layer can be realized. The LED chip 51 capable of emitting blue light is typically a diode composed of a group 13 nitride compound semiconductor, and includes the following formula In as an example _x Al _y Ga _1-x-y N (x is 0 to 1 inclusive, y is 0 to 1 inclusive, and x+y is 0 to 1 inclusive). As a typical example of a phosphor that emits yellow light by excitation with blue light, Y is given ₃ Al ₅ O ₁₂ ：Ce(YAG：Ce)、(Ba，Sr，Mg) ₂ SiO ₄ ：Eu，Mn。

For example, by using the LED chip 51 that emits blue-green light and a phosphor that emits red light of a complementary color to the blue-green light, a structure in which white light is emitted from the phosphor layer can be realized.

The phosphor layer may include a plurality of types of phosphors, or may be configured to emit light of different colors. For example, emission from the phosphor layer may be achieved using an LED chip 51 that emits blue light, a phosphor that emits red light, and a phosphor that emits green lightWhite light structure. As typical examples of the phosphor that emits red light by excitation with blue light, (Ca, sr) S: eu, sr ₂ Si ₇ Al ₃ ON ₁₃ : eu. As a typical example of a phosphor that emits green light when excited by blue light, srGa is given ₂ S ₄ ：Eu、Sr ₃ Si ₁₃ Al ₃ O ₂ N ₂₁ ：Eu。

In addition, a structure in which white light is emitted from the phosphor layer may be realized using the LED chip 51 that emits near ultraviolet light or violet light, the phosphor that emits red light, the phosphor that emits green light, and the phosphor that emits blue light. As typical examples of the phosphor that emits red light by excitation with near ultraviolet light or violet light, (Ca, sr) S: eu, sr ₂ Si ₇ Al ₃ ON ₁₃ ：Eu、La ₂ O ₂ S: eu. As a typical example of a phosphor that emits green light when excited by near ultraviolet light or violet light, srGa is given ₂ S ₄ ：Eu、Sr ₃ Si ₁₃ Al ₃ O ₂ N ₂₁ : eu. As a typical example of a phosphor that emits blue light when excited by near ultraviolet light or violet light, sr is given ₁₀ (PO ₄ ) ₆ Cl ₂ ：Eu、(Sr，Ba，Ca) ₁₀ (PO ₄ ) ₆ Cl ₂ ：Eu。

Note that near ultraviolet light has a maximum peak at a wavelength of 200nm to 380nm of the emission spectrum. In addition, the violet light has a maximum peak at a wavelength of 380nm to 430nm of an emission spectrum. In addition, blue light has a maximum peak at a wavelength of 430nm to 490nm of an emission spectrum. In addition, green light has a maximum peak at a wavelength of 490nm to 550nm of an emission spectrum. In addition, the yellow light has a maximum peak at a wavelength of 550nm to 590nm of the emission spectrum. In addition, the red light has a maximum peak at a wavelength of 640nm to 770nm of the emission spectrum.

When the phosphor layer includes a phosphor that emits yellow light and the LED chip 51 that emits blue light is used, it is preferable that the light emitted by the LED chip 51 has a maximum peak at a wavelength of 330nm to 500nm of an emission spectrum, more preferably a maximum peak at a wavelength of 430nm to 490nm, still more preferably a maximum peak at a wavelength of 450nm to 480 nm. This can efficiently excite the fluorescent material. In addition, the light emitted from the LED chip 51 has a maximum peak at 430nm to 490nm of the emission spectrum, and blue light of excitation light and yellow light from the phosphor can be mixed to become white light. Further, white with high purity can be realized by the light emitted by the LED chip 51 having a maximum peak at 450nm to 480 nm.

The above is a description of a structural example of the LED chip 51.

At least a part of this embodiment can be implemented in combination with other embodiments described in this specification as appropriate.

Embodiment 4

In this embodiment, a detailed description will be given of an example of the display device described in embodiment 1, embodiment 2, or embodiment 3.

Fig. 17 shows an example of a cross-sectional view of the display device 700A.

The display device 700A includes a first substrate 745 and a second substrate 740 bonded together with a resin 732.

The first substrate 745 has the pixel region 702 provided thereon. In addition, a plurality of light emitting elements 782 are disposed in the pixel region 702.

The structure of the transistor included in the pixel region 702 is not particularly limited. As the semiconductor layer of the transistor, one or more of a single crystal semiconductor, a polycrystalline semiconductor, a microcrystalline semiconductor, and an amorphous semiconductor can be used. As the semiconductor material, silicon or germanium can be used, for example. In addition, a compound semiconductor or an organic semiconductor typified by silicon germanium, silicon carbide, gallium arsenide, an oxide semiconductor, or a nitride semiconductor can also be used.

In addition, when an organic semiconductor is used as the semiconductor layer, a low-molecular organic material having an aromatic ring or a pi-electron conjugated conductive polymer can be used. For example, rubrene, tetracene, pentacene, perylene diimide, tetracyanoquinodimethane, polythiophene, polyacetylene, poly-p-phenylenevinylene may be used.

The transistor used in this embodiment mode preferably includes an oxide semiconductor film which is highly purified and formation of oxygen vacancies is suppressed. The transistor may have a low off-state current. Therefore, the holding time of the electric signal (image signal) can be prolonged, and the writing interval can be prolonged also in the on state. Therefore, the frequency of refresh operation can be reduced, and the effect of reducing power consumption can be exerted.

In addition, a transistor using an oxide semiconductor film (also referred to as an OS transistor) can obtain high field effect mobility, so that high-speed driving is possible. In addition, by using a transistor capable of high-speed driving in a pixel region, a high-quality image can be provided.

The transistor using the oxide semiconductor film may be appropriately manufactured by a known technique, and a manufacturing method is not particularly limited. In fig. 17, the transistor 750 can be regarded as one of top gate transistors including a back gate electrode. The potential of the back gate electrode may be equal to the gate electrode, or may be a ground potential (GND potential) or an arbitrary potential. In addition, by changing the potential of the back gate electrode independently without interlocking with the gate electrode, the threshold voltage of the transistor can be changed.

Further, since the gate electrode and the back gate electrode are formed using conductive layers, the function of preventing an electric field generated outside the transistor from affecting the semiconductor layer forming the channel (particularly, an electric field shielding function against static electricity) is provided. In addition, when the back gate electrode is formed larger than the semiconductor layer so as to cover the semiconductor layer with the back gate electrode, the electric field shielding function can be improved.

The display device 700A shown in fig. 17 includes a wiring portion 711, a pixel region 702, and a source driver circuit portion 704. The lead wiring portion 711 includes a signal line 710. In addition, the pixel region 702 includes a transistor 750 and a capacitor 790. The gate drive circuit section 704 includes a transistor 752. Although not shown here, a source driver circuit portion including a transistor may be provided. The gate driver circuit portion 704 and the source driver circuit portion may be mounted as ICs in other portions without being mounted on the first substrate 745.

The capacitor 790 shown in fig. 17 includes a lower electrode formed by processing a film which is the same film as the first gate electrode included in the transistor 750, and an upper electrode formed by processing the same metal oxide as the semiconductor layer. The upper electrode is reduced in resistance, as in the source region and the drain region of the transistor 750. In addition, a part of an insulating film which is used as a first gate insulating layer of the transistor 750 is provided between the lower electrode and the upper electrode. That is, the capacitor 790 has a stacked-layer structure in which an insulating film serving as a dielectric film is sandwiched between a pair of electrodes. The upper electrode is electrically connected to a wiring formed by processing the same film as the source electrode and the drain electrode of the transistor.

Further, an insulating layer 770 is provided over the transistor 750, the transistor 752, and the capacitor 790. The insulating layer 770 functions as a planarizing film, and top surfaces of the conductive layer 772 and the conductive layer 774 provided over the insulating layer 770 can be planarized. Since the conductive layer 772 and the conductive layer 774 are on the same surface and the top surfaces of the conductive layer 772 and the conductive layer 774 are flat, the conductive layer 772 and the conductive layer 774 can be easily electrically connected to the light emitting element 782.

The conductive layers 772 and 774 are electrically connected to the light emitting element 782 through the conductive bumps 791 and 793. Fig. 17 shows a structure in which the height of the cathode-side electrode and the height of the anode-side electrode included in the light emitting element 782 are different, and the heights of the bump 791 and the bump 793 are different. Note that when the height of the cathode-side electrode and the anode-side electrode included in the light-emitting element 782 are the same, a structure in which the heights of the bump 791 and the bump 793 are substantially uniform can be realized.

As shown in fig. 17, the transistor 750 included in the pixel region 702 is preferably disposed under the conductive layer 772 so as to overlap therewith. By having a region where the transistor 750 (particularly a channel formation region) overlaps with the conductive layer 772, light emitted from the light-emitting element 782 or external light can be prevented from reaching the transistor 750, and variation in electrical characteristics of the transistor 750 can be prevented.

The transistor 750 included in the pixel region 702 and the transistor 752 included in the gate driver circuit portion 704 may have different structures. For example, a structure in which one uses a top gate transistor and the other uses a bottom gate transistor may be employed. The source driver circuit portion is similar to the gate driver circuit portion 704.

The signal line 710 is formed of the same conductive film as the source and drain electrodes of the transistors 750 and 752. Here, a low-resistance material typified by a material containing a copper element is preferably used, whereby signal delay due to wiring resistance can be reduced, and a large-screen display can be realized.

Since a substrate having flexibility is used as the first substrate 745, an insulating layer having barrier properties against water or hydrogen is preferably provided between the first substrate 745 and the transistor 750. Further, the laminated structure of the first substrate 745, the adhesive layer 742, the resin layer 743, and the insulating layer 744 is provided. The transistor 750 or the capacitor 790 is provided over an insulating layer 744 provided over the resin layer 743. The resin layer 743 is bonded to the first substrate 745 through the adhesive layer 742. The resin layer 743 is preferably thinner than the first substrate 745.

The second substrate 740 is bonded to the resin 732. The second substrate 740 may use a resin film. In addition, the second substrate 740 may use an optical member (such as a diffusion plate), an input device typified by a touch sensor panel, or a stacked structure of two or more of the above.

A light shielding layer 738, a coloring layer 736, and a phosphor layer 797 are provided on the second substrate 740 side. The coloring layer 736 is disposed on the light emitting element 782. The phosphor layer 797 is provided between the light emitting element 782 and the coloring layer 736. The phosphor layer 797, the light emitting element 782, and the coloring layer 736 have regions overlapping with each other. As shown in fig. 17, the end of the phosphor layer 797 is preferably located outside the end of the light emitting element 782, and the end of the coloring layer 736 is preferably located outside the end of the phosphor layer 797. By adopting the above structure, light leakage to adjacent pixels and color mixing between pixels can be suppressed. Further, by providing the light shielding layer 738 between the adjacent coloring layer 736, glare of external light can be reduced, and a display device with high contrast can be realized.

For example, white light is emitted from the phosphor layer 797 by adopting a structure in which the phosphor layer 797 includes a phosphor that emits yellow light and the light emitting element 782 emits blue light. Light emitted from the light-emitting element 782 provided in a region overlapping with the coloring layer 736 transmitting red light is transmitted through the phosphor layer 797 and the coloring layer 736 and is emitted as red light to the display surface side. Similarly, light emitted from the light-emitting element 782 provided in a region overlapping with the coloring layer 736 transmitting green light is emitted as green light. Light emitted from the light emitting element 782 provided in a region overlapping with the coloring layer 736 transmitting blue light is emitted as blue light. Thereby, color display can be performed using one kind of light emitting element 782. In addition, since one type of light emitting element 782 is used as the display device, the manufacturing process can be simplified. In other words, according to one embodiment of the present invention, a display device having high brightness and contrast, high response speed, and low power consumption can be realized at low manufacturing cost.

For example, a structure in which the phosphor layer 797 includes a phosphor that emits red light and the light emitting element 782 emits blue-green light, and a structure in which white light is emitted from the phosphor layer 797 may be employed.

Further, the phosphor layer 797 may include a red-emitting phosphor, a green-emitting phosphor, and a blue-emitting phosphor, and the light-emitting element 782 may emit near ultraviolet light or violet light, so that white light is emitted from the phosphor layer 797.

The display device 700A shown in fig. 17 includes a light emitting element 782. As the light emitting element 782, a face-down LED chip may be used.

The coloring layer 736 is provided at a position overlapping the light emitting element 782, and the light shielding layer 738 is provided at a position overlapping an end portion of the coloring layer 736, the wiring portion 711, and the gate driving circuit portion 704. The phosphor layer 797, the coloring layer 736, and the light shielding layer 738 are filled with the resin 732 between the light emitting element 782.

The resin layer 795 is provided adjacent to the light emitting element 782. The resin layer 795 is preferably disposed between adjacent light emitting elements 782.

The thin films (insulating film, semiconductor film, conductive film) constituting the display device can be formed by a sputtering method, a chemical vapor deposition (CVD: chemical Vapor Deposition) method, a vacuum evaporation method, a pulse laser deposition (PLD: pulsed Laser Deposition) method, or an atomic layer deposition (ALD: atomic Layer Deposition) method. As the CVD method, an ion-enhanced chemical vapor deposition (PECVD) method or a thermal CVD method may be used. As an example of the thermal CVD method, an organometallic chemical vapor deposition (MOCVD: metal Organic CVD) method can be used.

The thin films (insulating film, semiconductor film, conductive film) constituting the display device can be formed by spin coating, dipping, spraying, ink-jet, dispenser, screen printing, offset printing, doctor blade (doctor blade), slit coating, roll coating, curtain coating, or doctor blade coating.

In addition, when a thin film constituting a display device is processed, the processing can be performed by photolithography. In addition, an island-shaped thin film can be formed by a film formation method using a shadow mask. The thin film may be processed by nanoimprint, sandblasting, or peeling. The photolithography method is, for example, the following two methods. One is a method of forming a resist mask by applying a photosensitive resist material to a thin film to be processed, exposing the film to light through a mask, and then developing the film, and removing the resist mask by etching the thin film. Another method is a method of forming a photosensitive thin film, exposing the film to light, developing the film, and processing the film into a desired shape.

In the photolithography, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or light in which these light are mixed can be used as light for exposure. In addition, ultraviolet, krF laser, or ArF laser may also be used. In addition, exposure may also be performed using a liquid immersion exposure technique. As the light for exposure, extreme ultraviolet light (EUV: extreme ultraviolet-violet) or X-rays may be used. In addition, instead of the light for exposure, an electron beam may be used. When extreme ultraviolet light, X-rays, or electron beams are used, extremely fine processing can be performed, so that it is preferable. Note that, in performing exposure by scanning with an electron beam, a photomask is not required.

As a method of etching the thin film, a dry etching method, a wet etching method, and a sandblasting method can be used.

By arranging a plurality of the display devices 700A in an array, a display device having a large display surface can be realized. In addition, by arranging a plurality of the display devices 700A in an array on a support having a curved surface, a display surface having a curved surface can be realized.

At least a part of this embodiment can be implemented in combination with other embodiments described in this specification as appropriate.

Embodiment 5

In this embodiment mode, a metal oxide (referred to as an oxide semiconductor) that can be used for the OS transistor described in embodiment mode 4 above will be described.

The metal oxide for the OS transistor preferably contains at least indium or zinc, more preferably contains indium and zinc. For example, the metal oxide preferably contains indium, M (M is one or more selected from gallium, aluminum, yttrium, tin, silicon, boron, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, and cobalt), and zinc. In particular, M is preferably one or more selected from gallium, aluminum, yttrium, and tin, more preferably gallium.

The metal oxide may be formed by a sputtering method, a chemical vapor deposition (CVD: chemical Vapor Deposition) method typified by a metal organic chemical vapor deposition (MOCVD: metal Organic Chemical Vapor Deposition) method, or an atomic layer deposition (ALD: atomic Layer Deposition) method.

Hereinafter, an oxide containing indium (In), gallium (Ga), and zinc (Zn) is described as an example of a metal oxide. Note that oxides containing indium (In), gallium (Ga), and zinc (Zn) are sometimes referred to as In-Ga-Zn oxides.

< classification of Crystal Structure >

Examples of the crystalline structure of the oxide semiconductor include amorphous (including completely amorphous), CAAC (c-axis-aligned crystalline), nc (nanocrystalline), CAC (closed-aligned composite), single crystal (single crystal), and polycrystalline (poly crystal).

The crystalline structure of the film or substrate can be evaluated using X-Ray Diffraction (XRD) spectroscopy. For example, the XRD spectrum measured by GIXD (Graving-incoedence XRD) measurement can be used for evaluation. Furthermore, the GIXD process is also referred to as a thin film process or a Seemann-Bohlin process. Hereinafter, the XRD spectrum obtained by the GIXD measurement may be simply referred to as XRD spectrum.

For example, the peak shape of the XRD spectrum of the quartz glass substrate is substantially bilaterally symmetrical. On the other hand, the peak shape of the XRD spectrum of the In-Ga-Zn oxide film having a crystal structure is not bilaterally symmetrical. The shape of the peaks of the XRD spectrum are left-right asymmetric to indicate the presence of crystals in the film or in the substrate. In other words, unless the XRD spectrum peak shape is bilaterally symmetrical, it cannot be said that the film or substrate is in an amorphous state.

In addition, the crystalline structure of the film or substrate can be evaluated using a diffraction pattern (also referred to as a nanobeam electron diffraction pattern) observed by a nanobeam electron diffraction method (NBED: nano Beam Electron Diffraction). For example, it can be confirmed that the quartz glass is in an amorphous state by observing a halo pattern in a diffraction pattern of the quartz glass substrate. In addition, a spot-like pattern was observed In the diffraction pattern of the In-Ga-Zn oxide film formed at room temperature, and no halation was observed. It is therefore presumed that the In-Ga-Zn oxide film formed at room temperature is In an intermediate state that is neither single crystal or polycrystalline nor amorphous, and it is not possible to draw conclusions that the In-Ga-Zn oxide film is amorphous.

Structure of oxide semiconductor

In addition, in the case of focusing attention on the structure of an oxide semiconductor, the classification of the oxide semiconductor may be different from the above classification. For example, oxide semiconductors can be classified into single crystal oxide semiconductors and non-single crystal oxide semiconductors other than the single crystal oxide semiconductors. Examples of the non-single crystal oxide semiconductor include the CAAC-OS and nc-OS described above. Further, a polycrystalline oxide semiconductor, an a-like OS (amorphorus-like oxide semiconductor), and an amorphous oxide semiconductor are included in the non-single crystal oxide semiconductor.

Details of the CAAC-OS, nc-OS, and a-like OS will be described herein.

[CAAC-OS]

The CAAC-OS is an oxide semiconductor including a plurality of crystal regions, the c-axis of which is oriented in a specific direction. The specific direction refers to the thickness direction of the CAAC-OS film, the normal direction of the surface on which the CAAC-OS film is formed, or the normal direction of the surface of the CAAC-OS film. The crystallization region is a region having periodicity of atomic arrangement. Note that the crystal region is also a region in which lattice arrangements are uniform when the atomic arrangements are regarded as lattice arrangements. The CAAC-OS may have a region where a plurality of crystal regions are connected in the a-b plane direction, and the region may have distortion. In addition, distortion refers to a portion in which the direction of lattice arrangement changes between a region in which lattice arrangements are uniform and other regions in which lattice arrangements are uniform among regions in which a plurality of crystal regions are connected. In other words, CAAC-OS refers to an oxide semiconductor that is c-axis oriented and has no significant orientation in the a-b plane direction.

Each of the plurality of crystal regions is composed of one or more fine crystals (crystals having a maximum diameter of less than 10 nm). In the case where the crystal region is composed of one minute crystal, the maximum diameter of the crystal region is less than 10nm. In the case where the crystal region is composed of a plurality of fine crystals, the size of the crystal region may be about several tens of nm.

In addition, the CAAC-OS has a layered crystal structure (also referred to as a layered structure) In which a layer containing indium (In) and oxygen (hereinafter, in layer), and a layer containing gallium (Ga), zinc (Zn), and oxygen (hereinafter, (Ga, zn) layer) are stacked In the In-Ga-Zn oxide. In addition, indium and gallium may be substituted for each other. Therefore, the (Ga, zn) layer sometimes contains indium. In addition, sometimes the In layer contains gallium. Note that sometimes the In layer contains zinc. The layered structure is observed as a lattice image, for example in a high resolution TEM (Transmission Electron Microscope) image.

For example, when structural analysis is performed on a CAAC-OS film using an XRD device, a peak representing c-axis orientation is detected at or near 2θ=31° in Out-of-plane XRD measurement using θ/2θ scanning. Note that the position (2θ value) of the peak representing the c-axis orientation may vary depending on the kind and composition of the metal element constituting the CAAC-OS.

Further, for example, a plurality of bright spots (spots) are observed in the electron diffraction pattern of the CAAC-OS film. In addition, when a spot of an incident electron beam (also referred to as a direct spot) passing through a sample is taken as a symmetry center, a certain spot and other spots are observed at a point-symmetrical position.

When the crystal region is observed from the above specific direction, the lattice arrangement in the crystal region is basically a hexagonal lattice, but the unit cell is not limited to a regular hexagon, and may be a non-regular hexagon. In addition, in the above-described distortion, there are cases where a pentagonal or heptagonal lattice arrangement is present. In addition, no clear grain boundary (grain boundary) was observed near the distortion of CAAC-OS. That is, distortion of the lattice arrangement suppresses the formation of grain boundaries. This is probably due to the capability of CAAC-OS to accommodate distortion due to the low density of the arrangement of oxygen atoms in the a-b direction, and the change in bonding distance between atoms due to the substitution of metal atoms.

In addition, it was confirmed that the crystal structure of the clear grain boundary was called poly crystal (polycrystalline). Since the grain boundary becomes a recombination center and carriers are trapped, there is a possibility that on-state current of the transistor is lowered and field-effect mobility is lowered. Therefore, CAAC-OS, in which no definite grain boundary is confirmed, is one of crystalline oxides that provide a semiconductor layer of a transistor with an excellent crystalline structure. Note that, in order to constitute the CAAC-OS, a structure containing Zn is preferable. For example, in—zn oxide and in—ga—zn oxide are preferable because occurrence of grain boundaries can be further suppressed as compared with In oxide.

CAAC-OS is an oxide semiconductor with high crystallinity and no clear grain boundary is confirmed. Therefore, it can be said that in the CAAC-OS, a decrease in electron mobility due to grain boundaries does not easily occur. Further, since crystallinity of an oxide semiconductor is sometimes lowered by contamination of impurities and generation of defects, CAAC-OS is said to be an oxide semiconductor having few impurities or defects (oxygen vacancies). Therefore, the physical properties of the oxide semiconductor including CAAC-OS are stable. Therefore, an oxide semiconductor including CAAC-OS has high heat resistance and high reliability. In addition, CAAC-OS is also stable to high temperatures (so-called thermal budget) in the manufacturing process. Thus, by using the CAAC-OS for the OS transistor, the degree of freedom in the manufacturing process can be increased.

[nc-OS]

In nc-OS, atomic arrangements in minute regions (for example, regions of 1nm to 10nm, particularly, regions of 1nm to 3 nm) have periodicity. In other words, nc-OS has a minute crystal. For example, the size of the fine crystals is 1nm to 10nm, particularly 1nm to 3nm, and the fine crystals are called nanocrystals. Furthermore, the nc-OS did not observe regularity of crystal orientation between different nanocrystals. Therefore, the orientation was not observed in the whole film. Therefore, nc-OS is sometimes not different from a-like OS or amorphous oxide semiconductor in some analytical methods. For example, when the nc-OS film is subjected to structural analysis by using an XRD device, a peak showing crystallinity is not detected in the Out-of-plane XRD measurement using θ/2θ scanning. In addition, when an electron diffraction (also referred to as selective electron diffraction) using an electron beam having a beam diameter larger than that of nanocrystals (for example, 50nm or more) is performed on the nc-OS film, a diffraction pattern resembling a halo pattern is observed. On the other hand, when an electron diffraction (also referred to as a "nanobeam electron diffraction") using an electron beam having a beam diameter equal to or smaller than the size of a nanocrystal (for example, 1nm or more and 30nm or less) is performed on an nc-OS film, an electron diffraction pattern in which a plurality of spots are observed in an annular region centered on a direct spot may be obtained.

[a-like OS]

The a-like OS is an oxide semiconductor having a structure between nc-OS and an amorphous oxide semiconductor. The a-like OS contains holes or low density regions. That is, the crystallinity of the a-like OS is lower than that of nc-OS and CAAC-OS. The concentration of hydrogen in the film of a-like OS is higher than that in the films of nc-OS and CAAC-OS.

Constitution of oxide semiconductor

Next, details of the CAC-OS will be described. CAC-OS is related to material composition.

[CAC-OS]

The CAC-OS refers to, for example, a constitution in which elements contained in a metal oxide are unevenly distributed, wherein the size of a material containing unevenly distributed elements is 0.5nm or more and 10nm or less, preferably 1nm or more and 3nm or less or an approximate size. Note that a state in which one or more metal elements are unevenly distributed in a metal oxide and a region including the metal elements is mixed is also referred to as a mosaic shape or a patch shape hereinafter, and the size of the region is 0.5nm or more and 10nm or less, preferably 1nm or more and 3nm or less or an approximate size.

The CAC-OS is a structure in which a material is divided into a first region and a second region, and the first region is mosaic-shaped and distributed in a film (hereinafter also referred to as cloud-shaped). That is, CAC-OS refers to a composite metal oxide having a structure in which the first region and the second region are mixed.

Here, the atomic number ratios of In, ga and Zn with respect to the metal elements constituting the CAC-OS of the In-Ga-Zn oxide are each represented by [ In ], [ Ga ] and [ Zn ]. For example, in CAC-OS of In-Ga-Zn oxide, the first region is a region whose [ In ] is larger than that In the composition of the CAC-OS film. Further, the second region is a region whose [ Ga ] is larger than [ Ga ] in the composition of the CAC-OS film. Further, for example, the first region is a region whose [ In ] is larger than that In the second region and whose [ Ga ] is smaller than that In the second region. Further, the second region is a region whose [ Ga ] is larger than that In the first region and whose [ In ] is smaller than that In the first region.

Specifically, the first region is a region mainly composed of indium oxide or indium zinc oxide. The second region is a region mainly composed of gallium oxide or gallium zinc oxide. In other words, the first region may be referred to as a region mainly composed of In. The second region may be referred to as a region containing Ga as a main component.

Note that a clear boundary between the first region and the second region may not be observed.

The CAC-OS In the In-Ga-Zn oxide is constituted as follows: in the material composition containing In, ga, zn, and O, a region having a part of the main component Ga and a region having a part of the main component In are irregularly present In a mosaic shape. Therefore, it is presumed that the CAC-OS has a structure in which metal elements are unevenly distributed.

The CAC-OS can be formed by, for example, sputtering without intentionally heating the substrate. In the case of forming CAC-OS by the sputtering method, as the deposition gas, any one or more selected from inert gas (typically argon), oxygen gas, and nitrogen gas may be used. In addition, the lower the flow rate ratio of the oxygen gas in the total flow rate of the deposition gas at the time of deposition, the better. For example, the flow rate ratio of the oxygen gas in the total flow rate of the deposition gas at the time of deposition is set to 0% or more and less than 30%, preferably 0% or more and 10% or less.

For example, in CAC-OS of In-Ga-Zn oxide, it was confirmed that the structure was mixed by unevenly distributing a region (first region) mainly composed of In and a region (second region) mainly composed of Ga based on an EDX-plane analysis (EDX-mapping) image obtained by an energy dispersive X-ray analysis method (EDX: energy Dispersive X-ray spectroscopy).

Here, the first region is a region having higher conductivity than the second region. That is, when carriers flow through the first region, conductivity as a metal oxide is exhibited. Thus, when the first region is distributed in a cloud in the metal oxide, high field effect mobility (μ) can be achieved.

On the other hand, the second region is a region having higher insulation than the first region. That is, when the second region is distributed in the metal oxide, leakage current can be suppressed.

In the case of using the CAC-OS for the transistor, the CAC-OS can be provided with a switching function (a function of controlling on/off) by a complementary effect of the conductivity due to the first region and the insulation due to the second region. In other words, the CAC-OS material has a conductive function in one part and an insulating function in the other part, and has a semiconductor function in the whole material. By separating the conductive function from the insulating function, each function can be improved to the maximum extent. Thus, by using CAC-OS forA transistor capable of realizing a large on-state current (I _on ) High field effect mobility (μ) and good switching operation.

Further, a transistor using CAC-OS has high reliability. Therefore, CAC-OS is most suitable for various semiconductor devices typified by display devices.

Oxide semiconductors have various structures and various characteristics. The oxide semiconductor according to one embodiment of the present invention may include two or more kinds of amorphous oxide semiconductor, polycrystalline oxide semiconductor, a-like OS, CAC-OS, nc-OS, and CAAC-OS.

< transistor with oxide semiconductor >

Next, a case where the above oxide semiconductor is used for a transistor will be described.

By using the oxide semiconductor described above for a transistor, a transistor with high field effect mobility can be realized. Further, a transistor with high reliability can be realized.

An oxide semiconductor having a low carrier concentration is preferably used for the transistor. For example, the carrier concentration in the oxide semiconductor is 1×10 ¹⁷ cm ^-3 Hereinafter, it is preferably 1X 10 ¹⁵ cm ^-3 Hereinafter, more preferably 1X 10 ¹³ cm ^-3 Hereinafter, it is more preferable that 1×10 ¹¹ cm ^-3 Hereinafter, it is more preferably less than 1X 10 ¹⁰ cm ^-3 And 1×10 ^-9 cm ^-3 The above. In the case of aiming at reducing the carrier concentration of the oxide semiconductor film, the impurity concentration in the oxide semiconductor film can be reduced to reduce the defect state density. In the present specification, a state in which the impurity concentration is low and the defect state density is low is referred to as "high-purity intrinsic" or "substantially high-purity intrinsic". Further, an oxide semiconductor having a low carrier concentration is sometimes referred to as a "high-purity intrinsic or substantially high-purity intrinsic oxide semiconductor".

Since the high-purity intrinsic or substantially high-purity intrinsic oxide semiconductor film has a low defect state density, it is possible to have a low trap state density.

Further, it takes a long time until the charge trapped in the trap state of the oxide semiconductor disappears, and the charge may act like a fixed charge. Therefore, the transistor in which the channel formation region is formed in the oxide semiconductor having a high trap state density may have unstable electrical characteristics.

Therefore, in order to stabilize the electrical characteristics of the transistor, it is effective to reduce the impurity concentration in the oxide semiconductor. In order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in a nearby film. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon. Note that impurities in an oxide semiconductor refer to elements other than the main component constituting the oxide semiconductor, for example. For example, an element having a concentration of less than 0.1 atomic% can be said to be an impurity.

< impurity >

Here, the influence of each impurity in the oxide semiconductor will be described.

When the oxide semiconductor contains silicon or carbon which is one of group 14 elements, a defect state is formed in the oxide semiconductor. Therefore, the concentration of silicon or carbon in the oxide semiconductor or in the vicinity of the interface with the oxide semiconductor (concentration measured by secondary ion mass spectrometry (SIMS: secondary Ion Mass Spectrometry)) was set to 2X 10 ¹⁸ atoms/cm ³ Hereinafter, it is preferably 2X 10 ¹⁷ atoms/cm ³ The following is given.

In addition, when the oxide semiconductor contains an alkali metal or an alkaline earth metal, a defect state is sometimes formed to form carriers. Therefore, a transistor using an oxide semiconductor containing an alkali metal or an alkaline earth metal easily has normally-on characteristics. Thus, the concentration of the alkali metal or alkaline earth metal in the oxide semiconductor measured by SIMS was made 1X 10 ¹⁸ atoms/cm ³ Hereinafter, it is preferably 2X 10 ¹⁶ atoms/cm ³ The following is given.

When the oxide semiconductor contains nitrogen, electrons are easily generated as carriers, and the carrier concentration is increased, so that the oxide semiconductor is n-type. As a result, a transistor using an oxide semiconductor containing nitrogen for a semiconductor tends to have normally-on characteristics. Alternatively, when the oxide semiconductor contains nitrogen, a trap state may be formed. As a result, there areThe electrical characteristics of the transistor are unstable. Therefore, the nitrogen concentration in the oxide semiconductor measured by SIMS is set to be lower than 5X 10 ¹⁹ atoms/cm ³ Preferably 5X 10 ¹⁸ atoms/cm ³ Hereinafter, more preferably 1X 10 ¹⁸ atoms/cm ³ Hereinafter, it is more preferable that the ratio is 5X 10 ¹⁷ atoms/cm ³ The following is given.

Hydrogen contained in the oxide semiconductor reacts with oxygen bonded to a metal atom to generate water, and thus oxygen vacancies are sometimes formed. When hydrogen enters the oxygen vacancy, electrons are sometimes generated as carriers. In addition, some of the hydrogen may be bonded to oxygen bonded to a metal atom, thereby generating electrons as carriers. Therefore, a transistor using an oxide semiconductor containing hydrogen easily has normally-on characteristics. Thus, it is preferable to reduce hydrogen in the oxide semiconductor as much as possible. Specifically, the hydrogen concentration in the oxide semiconductor measured by SIMS is set to be lower than 1×10 ²⁰ atoms/cm ³ Preferably less than 1X 10 ¹⁹ atoms/cm ³ More preferably less than 5X 10 ¹⁸ atoms/cm ³ More preferably less than 1X 10 ¹⁸ atoms/cm ³ 。

By using an oxide semiconductor whose impurity is sufficiently reduced for a channel formation region of a transistor, the transistor can have stable electrical characteristics.

At least a part of this embodiment can be implemented in combination with other embodiments described in this specification as appropriate.

Embodiment 6

In this embodiment mode, a structure example of a transistor which can be used in a display device according to one embodiment of the present invention will be described. In particular, a case where a transistor including silicon in a semiconductor layer in which a channel is formed is used will be described.

One embodiment of the present invention is a display device including a light emitting device and a pixel circuit. The display device can realize a full-color display device by including, for example, three light emitting elements that emit light of red (R), green (G), or blue (B), respectively.

As the transistor included in the pixel circuit for driving the light emitting device, a transistor including silicon in a semiconductor layer in which a channel is formed is preferably used. The silicon may be monocrystalline silicon, polycrystalline silicon, or amorphous silicon. In particular, a transistor (hereinafter, also referred to as LTPS transistor) including low-temperature polysilicon (LTPS (Low Temperature Poly Silicon)) in a semiconductor layer is preferably used. LTPS transistors have high field effect mobility and good frequency characteristics.

By using a transistor using silicon typified by an LTPS transistor, a circuit (e.g., a source driver circuit) which needs to be driven at a high frequency and a display portion can be formed over the same substrate. Therefore, an external circuit mounted to the display device can be simplified, and the component cost and the mounting cost can be reduced.

In addition, a transistor (hereinafter, also referred to as an OS transistor) including a metal oxide (hereinafter, also referred to as an oxide semiconductor) in the semiconductor layer in which a channel is formed is preferably used for at least one of the transistors included in the pixel circuit. The field effect mobility of an OS transistor is much higher than that of a transistor using amorphous silicon. In addition, the leakage current between the source and the drain in the off state of the OS transistor (hereinafter, also referred to as off-state current) is extremely low, and the charge stored in the capacitor connected in series with the transistor can be held for a long period of time. In addition, by using an OS transistor, power consumption of the display device can be reduced.

By using LTPS transistors for a part of transistors included in a pixel circuit and OS transistors for other transistors, a display device with low power consumption and high driving capability can be realized. As a more preferable example, an OS transistor is preferably used for a transistor used as a switch for controlling conduction/non-conduction between wirings and an LTPS transistor is preferably used for a transistor for controlling current.

For example, one of the transistors provided in the pixel circuit is used as a transistor for controlling a current flowing through the light emitting device, and may also be referred to as a driving transistor. One of a source and a drain of the driving transistor is electrically connected to a pixel electrode of the light emitting device. The driving transistor is preferably an LTPS transistor. Thereby, the current flowing through the light emitting device in the pixel circuit can be increased.

On the other hand, another of the transistors provided in the pixel circuit is used as a switch for controlling selection or non-selection of the pixel, and may also be referred to as a selection transistor. The gate of the selection transistor is electrically connected to a gate line, and one of the source and the drain is electrically connected to a source line (signal line). The selection transistor is preferably an OS transistor. Accordingly, even if the frame rate is made extremely small (for example, 1fps or less), the gradation of the pixel can be maintained, and therefore, by stopping the driving circuit when displaying a still image, the power consumption can be reduced.

A more specific structural example will be described below with reference to the drawings.

[ structural example of display device ]

Fig. 18A is a block diagram of a display device 610. The display device 610 includes a display portion 611, a driving circuit portion 612, and a driving circuit portion 613.

The display portion 611 includes a plurality of pixels 630 arranged in a matrix. The pixel 630 includes a sub-pixel 621R, a sub-pixel 621G, and a sub-pixel 621B. The sub-pixel 621R, the sub-pixel 621G, and the sub-pixel 621B each include a light emitting device serving as a display device.

The pixel 630 is electrically connected to the wiring GL, the wiring SLR, the wiring SLG, and the wiring SLB. The wiring SLR, the wiring SLG, and the wiring SLB are all electrically connected to the driving circuit portion 612. The wiring GL is electrically connected to the driving circuit portion 613. The driving circuit portion 612 is used as a source line driving circuit (also referred to as a source driver), and the driving circuit portion 613 is used as a gate line driving circuit (also referred to as a gate driver). The wiring GL is used as a gate line, and the wirings SLR, SLG, and SLB are all used as source lines.

The sub-pixel 621R includes a light emitting device that emits red light. The sub-pixel 621G includes a light emitting device emitting green light. The sub-pixel 621B includes a light emitting device that emits blue light. Thus, the display device 610 can realize full-color display. In addition, the pixel 630 may also include a sub-pixel having a light emitting device that emits light of other colors. For example, the pixel 630 may also include a sub-pixel having a light emitting device that emits white light or a sub-pixel having a light emitting device that emits yellow light in addition to the above three sub-pixels.

The wiring GL is electrically connected to the sub-pixel 621R, the sub-pixel 621G, and the sub-pixel 621B arranged in the row direction (extending direction of the wiring GL). The wirings SLR, SLG, and SLB are electrically connected to the sub-pixel 621R, the sub-pixel 621G, or the sub-pixel 621B (not shown) arranged in the column direction (extending direction of the wirings SLR), respectively.

[ structural example of Pixel Circuit ]

Fig. 18B shows an example of a circuit diagram of the pixel 621 which can be used for the above-described sub-pixel 621R, sub-pixel 621G, and sub-pixel 621B. The pixel 621 includes a transistor M1, a transistor M2, a transistor M3, a capacitor C1, and a light emitting element LED. In addition, the wiring GL and the wiring SL are electrically connected to the pixel 621. The wiring SL corresponds to any one of the wirings SLR, SLG, and SLB shown in fig. 18A.

The gate of the transistor M1 is electrically connected to the wiring GL, one of the source and the drain is electrically connected to the wiring SL, and the other of the source and the drain is electrically connected to one electrode of the capacitor C1 and the gate of the transistor M2. One of a source and a drain of the transistor M2 is electrically connected to the wiring AL, and the other of the source and the drain is electrically connected to one electrode of the light emitting device LED, the other electrode of the capacitor C1, and one of a source and a drain of the transistor M3. The gate of the transistor M3 is electrically connected to the wiring GL, and the other of the source and the drain is electrically connected to the wiring RL. The other electrode of the light emitting device LED is electrically connected to the wiring CL.

The wiring SL is supplied with the data potential D. The wiring GL is supplied with a selection signal. The selection signal includes a potential that places the transistor in a conductive state and a potential that places the transistor in a non-conductive state.

The wiring RL is supplied with a reset potential. The wiring AL is supplied with an anode potential. The wiring CL is supplied with a cathode potential. The anode potential in the pixel 621 is higher than the cathode potential. In addition, the reset potential supplied to the wiring RL may be such that the potential difference of the reset potential and the cathode potential is smaller than the threshold voltage of the light emitting device LED. The reset potential may be a potential higher than the cathodic potential, the same potential as the cathodic potential, or a potential lower than the cathodic potential.

The transistor M1 and the transistor M3 are used as switches. The transistor M2 is used as a transistor for controlling the current flowing through the light emitting device LED. For example, it can be said that the transistor M1 is used as a selection transistor and the transistor M2 is used as a driving transistor.

Here, LTPS transistors are preferably used for all of the transistors M1 to M3. Alternatively, it is preferable to use OS transistors for the transistors M1 and M3 and LTPS transistors for the transistor M2.

Alternatively, OS transistors may be used as all of the transistors M1 to M3. At this time, the following structure may be adopted: LTPS transistors are used as one or more of the plurality of transistors included in the driver circuit portion 612 and the plurality of transistors included in the driver circuit portion 613, and OS transistors are used as other transistors. For example, the following structure may be adopted: OS transistors are used as transistors provided in the display portion 611, and LTPS transistors are used as transistors provided in the driving circuit portion 612 and the driving circuit portion 613.

As the OS transistor, a transistor using an oxide semiconductor for a semiconductor layer in which a channel is formed can be used. For example, the semiconductor layer preferably contains indium, M (M is one or more selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, or magnesium), and zinc. In particular, M is preferably one or more selected from aluminum, gallium, yttrium and tin. In particular, as the semiconductor layer of the OS transistor, an oxide containing indium, gallium, and zinc (also referred to as IGZO) is preferably used. Alternatively, oxides containing indium, tin, and zinc are preferably used. Alternatively, oxides containing indium, gallium, tin, and zinc are preferably used.

A transistor using an oxide semiconductor whose band gap is wider than that of silicon and carrier density is low can realize extremely low off-state current. Because of its low off-state current, the charge stored in the capacitor connected in series with the transistor can be maintained for a long period of time. Therefore, in particular, the transistor M1 and the transistor M3 connected in series with the capacitor C1 are preferably transistors including an oxide semiconductor. By using a transistor including an oxide semiconductor as the transistor M1 and the transistor M3, leakage of charge held in the capacitor C1 through the transistor M1 or the transistor M3 can be prevented. In addition, the charge stored in the capacitor C1 can be held for a long period of time, and thus a still image can be displayed for a long period of time without rewriting the data of the pixel 621.

Note that in fig. 18B, the transistor is an n-channel type transistor, but a p-channel type transistor may be used.

In addition, each transistor included in the pixel 621 is preferably formed over the same substrate in an array.

As a transistor included in the pixel 621, a transistor including a pair of gates overlapping with a semiconductor layer interposed therebetween can be used.

In the case where a transistor including a pair of gates has a structure in which the pair of gates are electrically connected to each other and supplied with the same potential, there are advantages that: the on-state current of the transistor is increased; and saturation characteristics are improved. Further, a potential for controlling the threshold voltage of the transistor may be supplied to one of the pair of gates. In addition, by supplying a constant potential to one of the pair of gates, stability of the electrical characteristics of the transistor can be improved. For example, one gate of the transistor may be electrically connected to a wiring to which a constant potential is supplied, or one gate of the transistor may be electrically connected to a source or a drain of the transistor itself.

The pixel 621 illustrated in fig. 18C is an example of a case where a transistor including a pair of gates is used for the transistor M1 and the transistor M3. In each of the transistors M1 and M3, a pair of gates are electrically connected to each other. By adopting such a structure, the data writing period to the pixel 621 can be shortened.

The pixel 621 shown in fig. 18D is an example of a case where a transistor including a pair of gates is used for not only the transistor M1 and the transistor M3 but also the transistor M2. The pair of gates of the transistor M2 are electrically connected to each other. By using such a transistor for the transistor M2, saturation characteristics are improved, and thus control of the emission luminance of the light emitting device LED becomes easy, and display quality can be improved.

[ structural example of transistor ]

Hereinafter, a cross-sectional structure example of a transistor which can be used for the display device will be described.

Structural example 1

Fig. 19A is a cross-sectional view including a transistor 410.

The transistor 410 is a transistor which is provided over the substrate 401 and uses polysilicon for a semiconductor layer. For example, the transistor 410 corresponds to the transistor M2 of the pixel 621. That is, fig. 19A is an example in which one of a source and a drain of the transistor 410 is electrically connected to the conductive layer 431 of the light emitting device.

The transistor 410 includes a semiconductor layer 411, an insulating layer 412, and a conductive layer 413. The semiconductor layer 411 includes a channel formation region 411i and a low resistance region 411n. The semiconductor layer 411 contains silicon. The semiconductor layer 411 preferably contains polysilicon. A portion of the insulating layer 412 is used as a gate insulating layer. A portion of the conductive layer 413 is used as a gate electrode.

The semiconductor layer 411 may also contain a metal oxide (also referred to as an oxide semiconductor) that exhibits semiconductor characteristics. At this time, the transistor 410 may also be referred to as an OS transistor.

The low-resistance region 411n is a region containing an impurity element. For example, in the case where the transistor 410 is an n-channel transistor, phosphorus and arsenic may be added to the low-resistance region 411 n. On the other hand, when the transistor 410 is a p-channel transistor, boron or aluminum may be added to the low-resistance region 411 n. In addition, in order to control the threshold voltage of the transistor 410, the impurity described above may be added to the channel formation region 411i.

An insulating layer 421 is provided over the substrate 401. The semiconductor layer 411 is provided over the insulating layer 421. The insulating layer 412 is provided so as to cover the semiconductor layer 411 and the insulating layer 421. The conductive layer 413 is provided on the insulating layer 412 at a position overlapping with the semiconductor layer 411.

Further, an insulating layer 422 is provided so as to cover the conductive layer 413 and the insulating layer 412. The insulating layer 422 is provided with a conductive layer 414a and a conductive layer 414b. The conductive layer 414a and the conductive layer 414b are electrically connected to the low-resistance region 411n through openings formed in the insulating layer 422 and the insulating layer 412. A portion of the conductive layer 414a is used as one of a source electrode and a drain electrode, and a portion of the conductive layer 414b is used as the other of the source electrode and the drain electrode. Further, an insulating layer 423 is provided so as to cover the conductive layer 414a, the conductive layer 414b, and the insulating layer 422.

The insulating layer 423 is provided with a conductive layer 431 serving as a pixel electrode. The conductive layer 431 is provided over the insulating layer 423 and is electrically connected to the conductive layer 414b in an opening provided in the insulating layer 423. The LED terminals may be mounted on the conductive layer 431, which is not described here.

Structural example 2

Fig. 19B shows a transistor 410a including a pair of gate electrodes. The transistor 410a shown in fig. 19B is mainly different from the transistor 410 shown in fig. 19A in that: including conductive layer 415 and insulating layer 416.

The conductive layer 415 is disposed on the insulating layer 421. Further, an insulating layer 416 is provided so as to cover the conductive layer 415 and the insulating layer 421. The semiconductor layer 411 is provided so that at least the channel formation region 411i overlaps with the conductive layer 415 with the insulating layer 416 interposed therebetween.

In the transistor 410a shown in fig. 19B, a part of the conductive layer 413 is used as a first gate electrode, and a part of the conductive layer 415 is used as a second gate electrode. At this time, a portion of the insulating layer 412 is used as a first gate insulating layer, and a portion of the insulating layer 416 is used as a second gate insulating layer.

In the case where the first gate electrode and the second gate electrode are electrically connected, the conductive layer 413 and the conductive layer 415 may be electrically connected through openings formed in the insulating layer 412 and the insulating layer 416 in a region not shown. In the case where the second gate electrode is electrically connected to the source electrode or the drain electrode, the conductive layer 414a or the conductive layer 414b may be electrically connected to the conductive layer 415 through an opening formed in the insulating layer 422, the insulating layer 412, or the insulating layer 416 in a region not shown.

In the case where LTPS transistors are used as all the transistors constituting the pixel 621, the transistor 410 illustrated in fig. 19A or the transistor 410a illustrated in fig. 19B can be employed. In this case, the transistor 410a may be used as all the transistors constituting the pixel 621, the transistor 410 may be used as all the transistors, or the transistor 410a and the transistor 410 may be used in combination.

Structural example 3

Hereinafter, an example of a structure of a transistor including silicon for a semiconductor layer and a transistor including metal oxide for a semiconductor layer is described.

Fig. 19C is a schematic cross-sectional view including a transistor 410a and a transistor 450.

The above-described structure example 1 can be applied to the transistor 410a. Note that although an example using the transistor 410a is described here, a structure including the transistor 410 and the transistor 450 may be used, or a structure including all of the transistor 410, the transistor 410a, and the transistor 450 may be used.

The transistor 450 is a transistor using a metal oxide for a semiconductor layer. In the structure shown in fig. 19C, for example, the transistor 450 corresponds to the transistor M1 of the pixel 621, and the transistor 410a corresponds to the transistor M2. That is, fig. 19C shows an example in which one of a source and a drain of the transistor 410a is electrically connected to the conductive layer 431.

In addition, fig. 19C shows an example in which the transistor 450 includes a pair of gates.

The transistor 450 includes a conductive layer 455, an insulating layer 422, a semiconductor layer 451, an insulating layer 452, and a conductive layer 453. A portion of the conductive layer 453 is used as a first gate of the transistor 450 and a portion of the conductive layer 455 is used as a second gate of the transistor 450. At this time, a portion of the insulating layer 452 is used as a first gate insulating layer of the transistor 450, and a portion of the insulating layer 422 is used as a second gate insulating layer of the transistor 450.

The conductive layer 455 is disposed on the insulating layer 412. An insulating layer 422 is provided so as to cover the conductive layer 455. The semiconductor layer 451 is provided over the insulating layer 422. An insulating layer 452 is provided so as to cover the semiconductor layer 451 and the insulating layer 422. The conductive layer 453 is provided over the insulating layer 452, and has a region overlapping with the semiconductor layer 451 and the conductive layer 455.

Further, an insulating layer 426 is provided so as to cover the insulating layer 452 and the conductive layer 453. Conductive layer 454a and conductive layer 454b are provided over insulating layer 426. Conductive layer 454a and conductive layer 454b are electrically connected to semiconductor layer 451 through openings formed in insulating layer 426 and insulating layer 452. A portion of the conductive layer 454a is used as one of a source electrode and a drain electrode, and a portion of the conductive layer 454b is used as the other of the source electrode and the drain electrode. Further, an insulating layer 423 is provided so as to cover the conductive layer 454a, the conductive layer 454b, and the insulating layer 426.

Here, the conductive layers 414a and 414b which are electrically connected to the transistor 410a are preferably formed by processing the same conductive film as the conductive layers 454a and 454 b. Fig. 19C shows a structure in which the conductive layer 414a, the conductive layer 414b, the conductive layer 454a, and the conductive layer 454b are formed over the same surface (i.e., in contact with the top surface of the insulating layer 426) and contain the same metal element. At this time, the conductive layer 414a and the conductive layer 414b are electrically connected to the low-resistance region 411n through openings formed in the insulating layer 426, the insulating layer 452, the insulating layer 422, and the insulating layer 412. This is preferable because the manufacturing process can be simplified.

In addition, the conductive layer 413 used as the first gate electrode of the transistor 410a and the conductive layer 455 used as the second gate electrode of the transistor 450 are preferably formed by processing the same conductive film. Fig. 19C shows a structure in which the conductive layer 413 and the conductive layer 455 are formed over the same surface (i.e., in contact with the top surface of the insulating layer 412) and contain the same metal element. This is preferable because the manufacturing process can be simplified.

In fig. 19C, the insulating layer 452 serving as the first gate insulating layer of the transistor 450 covers an end portion of the semiconductor layer 451, but as in the transistor 450a shown in fig. 19D, the insulating layer 452 may be processed so that a top surface thereof matches or substantially matches a top surface of the conductive layer 453.

In this specification, "top surface shape substantially uniform" means that at least a part of the edge of each layer in the stack overlaps. For example, the case where part or all of the upper layer and the lower layer are processed by the same mask pattern is referred to. However, there are cases where the edges do not overlap in practice, for example, the upper layer is located inside the lower layer or the upper layer is located outside the lower layer, and this case can be said to be "the top surface shape is substantially uniform".

Note that an example in which the transistor 410a corresponds to the transistor M2 and is electrically connected to the pixel electrode is shown here, but is not limited thereto. For example, a structure in which the transistor 450 or the transistor 450a corresponds to the transistor M2 can be used. At this time, the transistor 410a corresponds to the transistor M1, the transistor M3, or other transistors.

This embodiment mode can be combined with other embodiment modes as appropriate.

Embodiment 7

The present embodiment relates to a display device in which sub-pixels are arranged in a matrix, and light emitting elements (light emitting diode chips) are provided for each of the sub-pixels.

The display device according to one embodiment of the present invention has a structure in which light emitting diode chips are mounted between sub-pixels of different colors. Here, in the display device according to one embodiment of the present invention, a plurality of subpixels that emit light of the same color are adjacently arranged not only in the column direction but also in the row direction. In other words, there is a structure in which a plurality of sub-pixels that emit light of the same color are divided independently.

In this specification, for example, two sub-pixels whose coordinates representing positions in the row direction are identical and whose coordinates representing positions in the column direction differ by 1 are referred to as sub-pixels adjacent in the row direction. For example, the sub-pixels of the 1 st row and the 2 nd column are adjacent to the sub-pixels of the 1 st row and the 1 st column in the row direction. In addition, two sub-pixels whose coordinates representing positions in the column direction are identical and whose coordinates representing positions in the row direction are different by 1 are referred to as sub-pixels adjacent in the column direction. For example, the sub-pixel of the 2 nd row and the 1 st column is adjacent to the sub-pixel of the 1 st row and the 1 st column in the column direction. The same expression method is used for the constituent elements other than the sub-pixels as long as the constituent elements are arranged in a matrix. For example, in the case where a plurality of sub-pixels that emit light of the same color are divided into four, they may be divided into two in the row direction and two in the column direction.

[ structural example of display device ]

Fig. 20 is a plan view showing a configuration example of a pixel 103 of a display device which is a display device according to an embodiment of the present invention.

The pixel 103 shown in fig. 20 is configured by four sub-pixels of the sub-pixel 110a, the sub-pixel 110b, the sub-pixel 110c, and the sub-pixel 110 d. The sub-pixels 110a, 110b, 110c, and 110d each include light emitting elements that emit light of different colors. The sub-pixels 110a, 110B, and 110c include four-color sub-pixels of red (R), green (G), blue (B), and white (W). The following structure may be adopted: the sub-pixel 110a shown in fig. 20 is made to correspond to one of the LED chips, and an LED chip having two terminals is mounted. In addition, a method of providing a plurality of sub-pixels on one chip may be employed to save time and labor for mounting. For example, an LED chip having four terminals may be provided for three-color sub-pixels of red (R), green (G), and blue (B) on one chip. Fig. 20 shows an example in which one chip is constituted by four color sub-pixels surrounded by a rectangle and arranged in a matrix. In the case of one chip constituted by sub-pixels of four colors, there are five terminals. Although the areas of the sub-pixels are the same in fig. 20, the area is not particularly limited, and for example, only the green sub-pixel may have a large area when the sub-pixels of three colors are used.

In this specification, for example, the contents common to the sub-pixels 110a, 110b, 110c, and 110d are described in some cases. In the case of describing common contents among constituent elements distinguished by letters, a description may be given by omitting letters.

The sub-pixels of row 1, column 1 to row 6, column 6 are shown in fig. 20.

In the present specification, the row direction is referred to as the X direction, and the column direction is referred to as the Y direction. The X-direction intersects, e.g., perpendicularly intersects, the Y-direction.

This embodiment mode can be combined with other embodiment modes as appropriate.

Embodiment 8

In this embodiment, an example of a display device according to an embodiment of the present invention will be described.

In the display apparatus of the present embodiment, the pixel may include a plurality of sub-pixels having light emitting devices that emit light of different colors from each other. For example, a pixel may include three sub-pixels. Examples of the three sub-pixels include three sub-pixels of red (R), green (G), and blue (B), and three sub-pixels of yellow (Y), cyan (C), and magenta (M). Alternatively, the pixel may include four sub-pixels. Examples of the four sub-pixels include a sub-pixel of four colors of R, G, B and white (W) and a sub-pixel of four colors of R, G, B, Y.

The arrangement of the sub-pixels is not particularly limited, and various arrangement methods may be employed. Examples of the arrangement of the subpixels include stripe arrangement, S-stripe arrangement, matrix arrangement, delta arrangement, bayer arrangement, and Pentile arrangement.

Examples of the top surface shape of the sub-pixel include a polygon typified by a triangle, a quadrangle (including a rectangle and a square), a pentagon, the above-mentioned polygon with rounded corners, an ellipse, and a circle. Here, the top surface shape of the sub-pixel corresponds to the top surface shape of the light emitting region of the light emitting device.

In a display device in which a pixel includes a light emitting device and a light receiving device, the pixel has a light receiving function, so that the display device can detect contact or proximity of an object while displaying an image. For example, not only all the subpixels included in the display device are caused to display an image, but also some of the subpixels may be caused to present light used as a light source and other subpixels may be caused to display an image.

The pixels shown in fig. 21A, 21B, and 21C include a sub-pixel G, a sub-pixel B, a sub-pixel R, and a sub-pixel PS.

The pixels shown in fig. 21A are arranged in stripes. The pixels shown in fig. 21B are arranged in a matrix.

As the pixel arrangement shown in fig. 21C, three sub-pixels (sub-pixel R, sub-pixel G, sub-pixel PS) are arranged in the vertical direction adjacent to one sub-pixel (sub-pixel B).

The pixel shown in fig. 21D includes a sub-pixel G, a sub-pixel B, a sub-pixel R, a sub-pixel IR, and a sub-pixel PS.

Fig. 21D shows an example in which one pixel is arranged on two rows. Three sub-pixels (sub-pixel G, sub-pixel B, sub-pixel R) are provided in the upper row (first row), and two sub-pixels (one sub-pixel PS and one sub-pixel IR) are provided in the lower row (second row).

Note that the layout of the sub-pixels is not limited to the structure of fig. 21A to 21D.

The subpixel R includes a light emitting device emitting red light. The subpixel G includes a light emitting device emitting green light. The sub-pixel B includes a light emitting device emitting blue light. The sub-pixel IR includes a light emitting device that emits infrared light. The sub-pixel PS includes a light receiving device. The wavelength of light detected by the subpixel PS is not particularly limited, and the light receiving device included in the subpixel PS preferably has sensitivity to light emitted by the light emitting device included in the subpixel R, subpixel G, subpixel B, or subpixel IR. For example, it is preferable to detect one or more of light in the wavelength region of blue, violet, bluish violet, green, yellowish green, yellow, orange, red and light in the wavelength region of infrared.

The light receiving area of the sub-pixel PS is smaller than the light emitting area of the other sub-pixels. The smaller the light receiving area is, the narrower the imaging range is, and the suppression of blurring of the imaging result and the improvement of resolution can be realized. Therefore, by using the sub-pixels PS, image capturing can be performed with higher definition or resolution. For example, imaging for personal recognition using a fingerprint, a palm print, an iris, a pulse shape (including a vein shape, an artery shape), or a face may be performed using the sub-pixels PS.

In addition, the sub-pixel PS may be used for a touch sensor (also referred to as a direct touch sensor) or an air touch sensor (also referred to as a hover sensor, hover touch sensor, non-contact sensor). For example, the sub-pixel PS preferably detects infrared light. Thus, a touch can be detected also in the dark.

Here, the touch sensor or the overhead touch sensor may detect proximity or contact of an object (finger, hand, or pen). The touch sensor can detect an object by directly contacting the object with the display device. In addition, the air touch sensor can detect an object even if the object does not contact the display device. For example, it is preferable that the display device can detect the object within a range in which the distance between the display device and the object is 0.1mm or more and 300mm or less, preferably 3mm or more and 50mm or less. By adopting this structure, the operation can be performed in a state where the object is not in direct contact with the display device, in other words, the display device can be operated in a non-contact (non-contact) manner. By adopting the above structure, it is possible to reduce the risk of the display device being stained or damaged or to operate the display device without the object directly contacting stains (e.g., garbage or viruses) attached to the display device.

Note that the non-contact sensor function may also be referred to as a hover sensor function, hover touch sensor function, air touch sensor function, non-contact sensor function. In addition, the touch sensor function may also be referred to as a direct touch sensor function.

In addition, the refresh frequency of the display device according to one embodiment of the present invention may be variable. For example, the refresh frequency may be adjusted (e.g., adjusted in a range of 0.01Hz or more and 240Hz or less) according to the content displayed on the display device to reduce power consumption. In addition, driving to reduce power consumption of the display device by driving to reduce the refresh frequency may also be referred to as idle stop (IDS) driving.

In addition, the driving frequency of the touch sensor or the air touch sensor may be changed according to the refresh frequency. For example, in the case where the refresh frequency of the display device is 120Hz, the driving frequency of the touch sensor or the air touch sensor may be a frequency higher than 120Hz (typically 240 Hz). By adopting this structure, low power consumption can be achieved, and the response speed of the touch sensor or the air touch sensor can be improved.

For high-definition imaging, the sub-pixels PS are preferably provided in all the pixels included in the display device. On the other hand, the sub-pixel PS does not need to have higher accuracy in the case of being used for a touch sensor or an air touch sensor than in the case of capturing a fingerprint, and therefore may be provided in a part of pixels included in the display device. By making the number of sub-pixels PS included in the display device smaller than the number of sub-pixels R, the detection speed can be increased.

Fig. 21E shows one example of a sub-pixel having a light receiving device, and fig. 21F shows one example of a sub-pixel having a light emitting device.

The pixel circuit PIX1 illustrated in fig. 21E includes a light receiving device PD, a transistor M11, a transistor M12, a transistor M13, a transistor M14, and a capacitor C2. Here, an example in which a photodiode is used as the light receiving device PD is shown.

The anode of the light receiving device PD is electrically connected to the wiring V1, and the cathode is electrically connected to one of the source and the drain of the transistor M11. The gate of the transistor M11 is electrically connected to the wiring TX, and the other of the source and the drain is electrically connected to one electrode of the capacitor C2, one of the source and the drain of the transistor M12, and the gate of the transistor M13. The gate of the transistor M12 is electrically connected to the wiring RES, and the other of the source and the drain is electrically connected to the wiring V2. One of a source and a drain of the transistor M13 is electrically connected to the wiring V3, and the other of the source and the drain is electrically connected to one of a source and a drain of the transistor M14. The gate of the transistor M14 is electrically connected to the wiring SE, and the other of the source and the drain is electrically connected to the wiring OUT 1.

The wiring V1, the wiring V2, and the wiring V3 are each supplied with a constant potential. When the light receiving device PD is driven with a reverse bias, a potential higher than the wiring V1 is supplied to the wiring V2. The transistor M12 is controlled by a signal supplied to the wiring RES, so that the potential of a node connected to the gate of the transistor M13 is reset to the potential supplied to the wiring V2. The transistor M11 is controlled by a signal supplied to the wiring TX, and controls the timing of the potential change of the above-described node in accordance with the current flowing through the light receiving device PD. The transistor M13 is used as an amplifying transistor for potential output according to the above-described node. The transistor M14 is controlled by a signal supplied to the wiring SE, and is used as a selection transistor for reading OUT an output according to the potential of the above-described node using an external circuit connected to the wiring OUT 1.

The pixel circuit PIX2 illustrated in fig. 21F includes a light emitting device LED, a transistor M15, a transistor M16, a transistor M17, and a capacitor C3. Here, an example using a light emitting diode as the light emitting device LED is shown. In particular, as the light emitting device LED, a red light emitting LED, a blue light emitting LED, or a green light emitting LED is preferably used.

The gate of the transistor M15 is electrically connected to the wiring VG, one of the source and the drain is electrically connected to the wiring VS, and the other of the source and the drain is electrically connected to one electrode of the capacitor C3 and the gate of the transistor M16. One of a source and a drain of the transistor M16 is electrically connected to the wiring V4, and the other of the source and the drain is electrically connected to the anode of the light emitting device LED and one of a source and a drain of the transistor M17. The gate of the transistor M17 is electrically connected to the wiring MS, and the other of the source and the drain is electrically connected to the wiring OUT 2. The cathode of the light emitting device LED is electrically connected to the wiring V5.

The wiring V4 and the wiring V5 are each supplied with a constant potential. The anode side and the cathode side of the light emitting device LED may be set to a high potential and a potential lower than the anode side, respectively. The transistor M15 is controlled by a signal supplied to the wiring VG and is used as a selection transistor for controlling the selection state of the pixel circuit PIX 2. Further, the transistor M16 is used as a driving transistor that controls a current flowing through the light emitting device LED according to a potential supplied to the gate. When the transistor M15 is in an on state, a potential supplied to the wiring VS is supplied to the gate of the transistor M16, and the light emission luminance of the light emitting device LED can be controlled according to the potential. The transistor M17 is controlled by a signal supplied to the wiring MS, and the potential between the transistor M16 and the light emitting device LED is output to the outside through the wiring OUT 2.

Here, the transistors M11, M12, M13, and M14 included in the pixel circuit PIX1, and the transistors M15, M16, and M17 included in the pixel circuit PIX2 are preferably transistors including metal oxides (oxide semiconductors) in the semiconductor layers forming the channels thereof.

Very low off-state currents can be achieved using transistors of metal oxides having wider band gaps than silicon and lower carrier densities. Thus, since the off-state current is small, the charge stored in the capacitor connected in series with the transistor can be held for a long period of time. Therefore, in particular, the transistors M11, M12, and M15 connected in series with the capacitor C2 or C3 are preferably transistors including an oxide semiconductor. In addition, by using a transistor to which an oxide semiconductor is similarly applied for other transistors, manufacturing cost can be reduced. Note that one embodiment of the present invention is not limited to this, and a transistor using silicon for a semiconductor layer (hereinafter also referred to as a Si transistor) may be used.

In addition, the off-state current value of the OS transistor per channel width of 1 μm at room temperature may be 1aA (1×10 ^-18 A) Hereinafter, 1zA (1×10) ^-21 A) The following or 1yA (1×10) ^-24 A) The following is given. Note that the off-state current value of the Si transistor at room temperature per channel width of 1 μm is 1fA (1×10 ^-15 A) Above and 1pA (1×10) ^-12 A) The following is given. Therefore, it can be said that the off-state current of the OS transistor is about 10 bits lower than the off-state current of the Si transistor.

In addition, when the transistor operates in the saturation region, the OS transistor can make a change in the source-drain current with a change in the gate-source voltage small as compared with the Si transistor. Therefore, by using an OS transistor as a driving transistor included in the pixel circuit, a current flowing between the source and the drain can be finely determined in accordance with a change in the gate-source voltage, so that the amount of current flowing through the light emitting device can be finely controlled. Thereby, the light emission luminance of the light emitting device can be finely controlled (the gradation of the pixel circuit can be increased).

In addition, regarding the saturation characteristics of the current flowing when the transistor operates in the saturation region, the OS transistor can flow a stable constant current (saturation current) even if the source-drain voltage is gradually increased as compared with the Si transistor. Therefore, by using the OS transistor as the driving transistor, even if, for example, the current-voltage characteristics of the light emitting device LED are uneven, a stable constant current can be caused to flow through the light emitting device. That is, the OS transistor hardly changes the source-drain current even if the source-drain voltage is increased when operating in the saturation region, and thus the light emission luminance of the light emitting device can be stabilized.

As described above, by using an OS transistor as a driving transistor included in a pixel circuit, it is possible to realize "suppression of black blur", "increase in emission luminance", "multi-gradation", and "suppression of non-uniformity of a light emitting device". Accordingly, a clear and smooth image can be displayed on a display device including a pixel circuit, and as a result, any one or more of sharpness of the image, and high contrast can be observed. In addition, by adopting a structure in which an off-state current which can flow through a driving transistor included in a pixel circuit is extremely low, black display performed on a display device can be made to be display in which light leakage is extremely small (solid black display).

In addition, the transistors M11 to M17 may also use transistors whose semiconductor layers forming channels thereof contain silicon. In particular, when silicon having high crystallinity typified by single crystal silicon or polycrystalline silicon is used, high field effect mobility and higher-speed operation can be realized, and thus it is preferable.

Further, one or more of the transistors M11 to M17 may be a transistor including an oxide semiconductor (an OS transistor), and other transistors may be a transistor including silicon (a Si transistor). As the Si transistor, a transistor including low-temperature polysilicon (LTPS: low Temperature Poly Silicon) (hereinafter referred to as LTPS transistor) can be used. In addition, a structure in which an OS transistor and an LTPS transistor are used in combination is sometimes referred to as LTPO. By employing LTPO, an LTPS transistor having high mobility and an OS transistor having low off-state current can be used, so that a display panel having high display quality can be provided.

In fig. 21E and 21F, an n-channel transistor is used as a transistor, but a p-channel transistor may be used.

The transistor included in the pixel circuit PIX1 and the transistor included in the pixel circuit PIX2 are preferably arranged over the same substrate. It is particularly preferable that the transistors included in the pixel circuit PIX1 and the transistors included in the pixel circuit PIX2 be formed in a mixed manner in one region and arranged periodically.

Further, it is preferable to provide one or more layers including one or both of a transistor and a capacitor at a position overlapping with the light receiving device PD or the light emitting device LED. Thus, the effective occupied area of each pixel circuit can be reduced, and a high-definition light receiving section or display section can be realized.

At least a part of this embodiment can be implemented in combination with other embodiments described in this specification as appropriate.

Embodiment 9

In this embodiment mode, an electronic device using a display device according to an embodiment of the present invention will be described with reference to fig. 22.

In this embodiment, an example is shown in which the display device described in any one of embodiments 1 to 4 is provided in a vehicle.

Fig. 22 is a diagram illustrating a structural example of the vehicle. Fig. 22 shows an instrument panel 151 disposed around the driver's seat, a display device 154 fixed to the front surface of the driver's seat, a camera 155, an air supply port 156, a door 158a on the right side of the driver's seat, and a door 158b on the left side of the driver's seat. The display device 154 is provided integrally in front of the driver's seat.

The display device 154 fixed to the front of the driver's seat may be any one of the display devices of embodiments 1 to 4. In fig. 22, the display device 154 is illustrated as one display surface, and an example in which a total of 18 light emitting devices in 2 rows and 9 columns are combined to form the display device 154 is shown. Note that although the boundaries of the pixel regions are shown by broken lines in fig. 22, the actual display image does not show broken lines, and is a structure without seams or with the seams inconspicuous. The display device 154 may have a see-through structure in which a light-transmitting region is provided so as to be visible.

The display device 154 is preferably provided with a touch sensor or a non-contact proximity sensor. Alternatively, it is preferable that a gesture operation can be performed using a separately provided camera.

Although fig. 22 shows an autonomous vehicle in which a steering wheel (also referred to as a steering wheel) is not provided, the present invention is not limited to this, and a steering wheel may be provided, and a display device having a curved surface may be provided on the steering wheel.

Further, a camera 155 for capturing a side rear situation may be provided outside the vehicle. Although fig. 22 shows an example in which the camera 155 is provided instead of the rearview mirror, both the rearview mirror and the camera may be provided. As the camera 155, a CCD camera or a CMOS camera can be used. In addition, an infrared camera may be used in combination with the camera. Since the output level of the infrared camera becomes high as the temperature of the subject becomes high, a living organism (human or animal) can be detected or extracted.

The image photographed by the camera 155 may be output to the display device 154. The display device 154 is mainly used for assisting driving of the vehicle. By capturing a wide-angle image of the side rear using the camera 155 and displaying the image on the display device 154, it is possible to prevent accidents by allowing the driver to see dead areas.

Further, the distance image sensor may be provided on the roof of the automobile, and an image obtained using the distance image sensor may be displayed on the display device 154. As the distance image sensor, an image sensor or a laser light radar (LIDAR: light Detection and Ranging) may be used. By displaying both the image obtained using the image sensor and the image obtained using the distance image sensor on the display device 154, more information can be provided to the driver to assist driving.

In addition, the display device 152 having a curved surface may be provided in the roof, i.e., in the ceiling portion of the automobile. When the display device 152 having a curved surface is provided in the ceiling portion, the display device shown in embodiment mode 1 or embodiment mode 2 can be used.

The display device 152 and the display device 154 may have a function of displaying map information, traffic information, television images, and DVD images.

The image displayed on the display device 154 can be freely set according to the preference of the driver. For example, a television image, a DVD image, and a web video may be displayed on the left image area, map information may be displayed on the image area in the center, and meters typified by a speedometer and a tachometer may be displayed on the right image area.

In fig. 22, a display device 159a and a display device 159b are provided along the surfaces of the right door 158a and the left door 158b, respectively. Both the display device 159a and the display device 159b may be formed using one or more light emitting devices. For example, a display surface is formed using 1 row and 2 column light emitting devices.

The display device 159a and the display device 159b are arranged so as to face each other.

In addition, it is preferable that a display device having an image capturing function be used as at least one of the display devices 152, 154, 159a, and 159b.

For example, when the driver touches an image area of at least one of the display devices 152, 154, 159a, and 159b, the vehicle may perform fingerprint recognition or biometric recognition of palm print recognition. The vehicle may also have a function of adjusting an environment that the person feels comfortable when the driver is recognized through biometric recognition. For example, it is preferable to perform one or more of the following processes after the recognition: adjusting the position of the seat; adjusting the position of a steering wheel; adjustment of the direction of the camera 155; setting brightness; setting an air conditioner; setting the speed (frequency) of the wiper; setting the volume of audio; and a readout process of a play list of audio.

In addition, the vehicle can be automatically set to a state in which the vehicle can be started, such as a state in which the engine is started or a state in which the electric vehicle can be started, when the driver is recognized by biometric recognition, without requiring a key that has been required so far, and is preferable.

Note that the display device surrounding the driver's seat is described here, but the display device may be provided in the rear seat so as to surround the occupant.

Further, another example will be described with reference to fig. 23.

Fig. 23 is a diagram illustrating a structural example of the vehicle. Fig. 23 shows an instrument panel 852, a steering wheel 841, a windshield 854, a camera 855, a blower 856, a passenger side door 858a, and a driver side door 858b, which are disposed around the driver's seat and the passenger seat. The display section 851 is provided on the entire left to right of the dashboard 852.

The steering wheel 841 includes a light receiving/emitting portion 840. The light receiving and emitting unit 840 has a light emitting function and an imaging function. Biological information such as a fingerprint, palm print, or vein of the driver can be acquired by the light receiving and emitting part 840, and the driver can be identified based on the biological information thereof. Therefore, only the driver who has logged in advance can start the vehicle, so that a vehicle with an extremely high safety level can be realized.

Further, a camera 855 for capturing a side rear situation may be provided outside the vehicle. Although fig. 23 shows an example in which a camera 855 is provided instead of the rearview mirror, both the rearview mirror and the camera may be provided. As the camera 855, a CCD camera or a CMOS camera can be used. In addition, an infrared camera may be used in combination with the camera. Since the output level of the infrared camera becomes high as the temperature of the subject becomes high, a living organism (human or animal) can be detected or extracted.

The image captured by the camera 855 may be output to either one or both of the display portion 851 and the light emitting/receiving portion 840. The display portion 851 or the light emitting/receiving portion 840 is mainly used for assisting driving of the vehicle. By capturing a wide-angle image of the side rear using the camera 855 and displaying the image on the display portion 851 or the light emitting/receiving portion 840, it is possible to prevent an accident by allowing the driver to see a dead angle area.

The display section 851 may have a function of displaying map information, traffic information, television images, and DVD images. For example, the display panel 880a and the display panel 880b are used as one display screen to display map information of a large size. The number of display panels may be increased according to the displayed image.

In fig. 23, a display section 851 is provided on the instrument panel, the center console, and the left and right uprights. Although fig. 23 shows an example in which the display portion 851 is composed of eight display panels (display panels 880a to 880 h), the number of display panels is not limited to this, and may be seven or less, or nine or more. The display panel 880c and the display panel 880d are provided at positions corresponding to the center console. Here, a combination of the display panel 800d and the non-rectangular display panel 800c is shown. When the display panel 880d and the display panel 880c are combined into one panel, the display panel 880d and the display panel 880c are formed as a rectangular panel as a whole. The display panel 880e and the display panel 880f are provided on the rear side of the instrument panel when viewed from the driver. The display panel 880g and the display panel 880h are provided along the column. One or more of the display panels 880a to 880h are disposed along the curved surface.

The images displayed on the display panels 880a to 880h can be freely set according to the preference of the driver. For example, a television image, a DVD image, a web video may be displayed on the right display panel 880a, the display panel 880e, map information on the display panel 880c in the center, instruments such as a speedometer, a tachometer on the display panel 880b, the display panel 880f on the driver side, and audio on the display panel 880d between the driver's seat and the passenger seat. In addition, by displaying the external scenery on the view line of the driver on the display panel 880g and the display panel 880h provided on the pillar in real time, it is possible to make a pillar-less vehicle possible to be plausibly, and to reduce dead angles, so that a vehicle with high safety can be realized.

In fig. 23, a display portion 859a and a display portion 859b are provided along the respective surfaces of the passenger side door 858a and the driver side door 858b, respectively. The display portion 859a and the display portion 859b may each be formed using one or more display panels.

The display portion 859a is arranged opposite to the display portion 859b, and the display portion 851 is provided on the dashboard 852 so as to connect an end portion of the display portion 859a and an end portion of the display portion 859b. Thus, the display portions 851, 859a, and 859b surround the front and both sides of the driver and the passenger of the passenger seat. For example, by displaying the continuous screen image on the display portion 859a, the display portion 851, and the display portion 859b, the driver or the passenger can feel a sense of immersion.

Further, a camera 855 for capturing a side rear situation may be provided outside the vehicle. Although fig. 23 shows an example in which a camera 855 is provided instead of the rearview mirror, both the rearview mirror and the camera may be provided.

As the camera 855, a CCD camera or a CMOS camera can be used. In addition, an infrared camera may be used in combination with the camera. Since the output level of the infrared camera becomes high as the temperature of the subject becomes high, a living organism (human or animal) can be detected or extracted.

The image photographed by the camera 855 may be output to any one or more of the display panels. The camera 855 may mainly assist driving the vehicle using the image displayed on the display portion 851. By capturing a wide-angle image of the side rear using the camera 855 and displaying the image on one or more of the display panels, it is possible to allow the driver to see a dead angle area to prevent an accident from occurring.

Further, an image that is combined from the images obtained by the camera 855 and is linked to a scene visible from the window may be displayed on the display portions 859a and 859 b. That is, the display portions 859a and 859b may display the transparent images of the doors 858a and 858b to the driver and the passenger. Thus, the driver and the passenger can enjoy the feeling of floating themselves.

In addition, a display panel having an image capturing function is preferably used as at least one of the display panels 880a to 880 h. The display panel having an image capturing function may be used as one or more of the display panels provided on the display portion 859a and the display portion 859 b.

As described above, by adopting the configuration of one embodiment of the present invention, the degree of freedom in design of the display device is improved, and the design of the display device can be improved. In addition, the display device according to one embodiment of the present invention is suitable for mounting to a vehicle.

At least a part of this embodiment can be implemented in combination with other embodiments described in this specification as appropriate.

Embodiment 10

In this embodiment, an electronic device according to an embodiment of the present invention will be described with reference to fig. 24A and 24B.

The electronic device according to the present embodiment includes the display device according to one embodiment of the present invention in the display portion. The display device according to one embodiment of the present invention is easy to achieve high definition and high resolution. Therefore, the display device can be used for display portions of various electronic devices.

Examples of the electronic device include electronic devices having a large screen such as a television set, a desktop or notebook personal computer, a display for a computer, a digital signage, and a large game machine typified by a pachinko machine, and digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, portable information terminals, and audio reproducing devices.

In particular, since the display device according to one embodiment of the present invention can improve the definition, the display device can be suitably used for an electronic apparatus including a small display portion. Examples of such electronic devices include wristwatch-type and bracelet-type information terminal devices (wearable devices), VR devices for head-mounted displays, glasses-type AR devices and MR devices, and wearable devices that can be mounted on the head.

The display device according to one embodiment of the present invention preferably has extremely high resolution such as HD (1280×720 in pixel number), FHD (1920×1080 in pixel number), WQHD (2560×1440 in pixel number), WQXGA (2560×1600 in pixel number), 4K (3840×2160 in pixel number), and 8K (7680×4320 in pixel number). In particular, the resolution is preferably set to 4K, 8K or more. In the display device according to one embodiment of the present invention, the pixel density (sharpness) is preferably 100ppi or more, more preferably 300ppi or more, still more preferably 500ppi or more, still more preferably 1000ppi or more, still more preferably 2000ppi or more, still more preferably 3000ppi or more, still more preferably 5000ppi or more, and still more preferably 7000ppi or more. By using the display device having one or both of high resolution and high definition, the sense of realism and sense of depth can be further improved in an electronic device for personal use in a portable or home use. The screen ratio (aspect ratio) of the display device according to one embodiment of the present invention is not particularly limited. For example, the display device may accommodate various screen ratios (e.g., aspect ratios of 1:1 (square), 4:3, 16:9, 16:10).

The electronic device of the present embodiment may also include a sensor (the sensor has a function of measuring force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, electric current, voltage, electric power, radiation, flow rate, humidity, inclination, vibration, smell, or infrared ray).

Fig. 24A shows an example of a television apparatus. In the television device 7100, a display unit 7000 is incorporated in a housing 7101. Here, a structure in which the housing 7101 is supported by a bracket 7103 is shown.

The display device according to one embodiment of the present invention can be applied to the display portion 7000. The display surface of the display unit 7000 has a curved surface, and any of the display devices of embodiments 1 to 3 can be applied thereto.

The television device 7100 shown in fig. 24A can be operated by an operation switch provided in the housing 7101 and a remote control operation device 7111 provided separately. The display unit 7000 may be provided with a touch sensor, or the television device 7100 may be operated by touching the display unit 7000 with a finger. The remote controller 7111 may be provided with a display unit for displaying information outputted from the remote controller 7111. By using the operation keys or touch panel provided in the remote control unit 7111, the channel and volume can be operated, and the video displayed on the display unit 7000 can be operated.

The television device 7100 includes a receiver and a modem. A general television broadcast may be received by using a receiver. Further, the communication network is connected to a wired or wireless communication network via a modem, whereby information communication is performed in one direction (from a sender to a receiver) or in two directions (between a sender and a receiver or between receivers).

Fig. 24B shows an example of a digital signage.

Fig. 24B shows a digital signage 7400 disposed on a cylindrical post 7401. The digital signage 7400 includes a display 7000 disposed along a curved surface of the post 7401.

In fig. 24B, a display device according to an embodiment of the present invention can be used for the display unit 7000.

The larger the display unit 7000 is, the larger the amount of information that can be provided at a time is. The larger the display unit 7000 is, the more attractive the user can be, for example, to improve the advertising effect.

By using the touch panel for the display unit 7000, not only a still image or a moving image can be displayed on the display unit 7000, but also a user can intuitively operate the touch panel, which is preferable. In addition, when used for providing route information or traffic information, the usability can be improved by intuitive operations.

As shown in fig. 24B, the digital signage 7400 can preferably be linked with an information terminal device 7411 as a smart phone carried by a user through wireless communication. For example, advertisement information displayed on the display portion 7000 may be displayed on the screen of the information terminal device 7411. Further, by operating the information terminal device 7411, the display of the display portion 7000 can be switched.

Further, a game can be executed on the digital signage 7400 with the screen of the information terminal device 7411 as an operation unit (controller). Thus, a plurality of users can participate in the game at the same time without specifying the users, and enjoy the game.

This embodiment mode can be combined with other embodiment modes as appropriate.

[ description of the symbols ]

10: support body, 11: support body, 12a: third substrate, 12b: fourth substrate, 12: substrate, 13: covering material, 14b: light emitting direction, 15: region, 16a: light-emitting panel, 16b: light emitting panel, 16c: light-emitting panel, 16d: light-emitting panel, 16e: fifth light-emitting panel, 16f: sixth light-emitting panel, 16g: seventh light emitting panel, 16h: eighth light-emitting panel, 17B: light emitting element, 17G: light emitting element, 17R: light emitting element, 17: light emitting diode chip, 18a: nitride film, 18b: nitride film, 19: resin, 21: electrode, 23: electrode, 51A: LED chip region, 51B: LED chip, 51: LED chip, 71A: substrate, 71: substrate, 75a: n-type contact layer, 75b: n-type cladding layer, 75: n-type semiconductor layer, 77a: barrier layer, 77b: well layer, 77: light emitting layer, 79a: p-type cladding layer, 79b: p-type contact layer, 79: p-type semiconductor layer, 81: semiconductor layer, 83: electrode, 85: electrode, 87: electrode, 89: insulating layer, 103: pixel, 110a: sub-pixels, 110b: sub-pixels, 110c: sub-pixels, 110d: sub-pixels, 151: instrument panel, 152: display device, 154: display device 155: camera, 156: supply-air port, 158a: door, 158b: door, 159a: display device, 159b: display device, 401: substrate, 410a: transistor, 410: transistor, 411i: channel formation region, 411n: low resistance region, 411: semiconductor layer, 412: insulating layer, 413: conductive layer, 414a: conductive layer, 414b: conductive layer, 415: conductive layer, 416: insulating layer 421: insulating layer, 422: insulating layer 423: insulating layer, 426: insulating layer, 431: conductive layer, 450a: transistor, 450: transistor, 451: semiconductor layer, 452: insulating layer, 453: conductive layer, 454a: conductive layer, 454b: conductive layer, 455: conductive layer, 610: display device, 611: display unit, 612: drive circuit portion, 613: drive circuit portion 621B: sub-pixels, 621G: sub-pixels, 621R: sub-pixels, 621: pixel, 630: pixel, 700A: display device, 700: laser irradiation line, 702: pixel region, 704: gate drive circuit sections 706: source drive circuit unit, 710: signal lines, 711: a lead wiring portion 732: resin, 736: coloring layer, 738: light shielding layer, 740: second substrate, 742: adhesive layer, 743: resin layer, 744: insulating layer, 745: first substrate, 750: transistor, 752: transistor, 770: insulating layer, 772: conductive layer, 774: conductive layer, 782: light emitting element, 790: capacitor, 791: bump, 793: bump, 795: resin layer, 797: phosphor layer, 800: substrate with flexibility, 801: second substrate, 810: a flexible substrate, 811: second substrate, 820: element layer 821: element layer, 840: light emitting and receiving section, 841: steering wheel, 851: display unit, 852: dashboard, 854: windshield, 855: camera, 856: supply port, 858a: door, 858b: door, 859a: display section, 859b: display unit, 880a: display panel, 880b: display panel, 880c: display panel, 880d: display panel, 880e: display panel, 880f: display panel, 880g: display panel, 880h: display panel, 900: LED chip substrate, 901: film, 903: plate, 905: work table 907: grindstone, 909: grinding wheel, 911: dividing line, 913: support table, 914: opening portion 915: blade, 919: first film, 921: first fixing means, 923: sheet, 924: plate, 925: second fixing means, 927: second film, 929: push-out mechanism, 950: device, 951: stage, 953: single axis robot, 955: single axis robot, 957: camera, 959: clamping mechanism, 961: control device, 963: unit, 7000: display unit, 7100: television apparatus, 7101: frame body, 7103: support, 7111: remote control operation machine, 7400: digital signage, 7401: column, 7411: information terminal equipment

Claims (6)

1. An electronic device, comprising:

a plurality of flexible substrates on which a plurality of light emitting diode chips are mounted;

a substrate provided with a nitride film; and

a resin between the substrate having flexibility and the substrate provided with the nitride film,

wherein light emitted from the light emitting diode chip passes through the substrate provided with the nitride film.

2. The electronic device according to claim 1,

wherein the flexible substrate has light transmittance.

3. The electronic device according to claim 1,

wherein the ends of adjacent ones of the plurality of flexible substrates overlap each other.

4. The electronic device according to claim 1,

wherein the substrate provided with the nitride film has light transmittance.

5. The electronic device according to claim 1,

wherein the resin has light transmittance.

6. The electronic device according to claim 1,

wherein the nitride film is a silicon nitride film.