CN117044397A

CN117044397A - Display device

Info

Publication number: CN117044397A
Application number: CN202280020647.3A
Authority: CN
Inventors: 柳泽悠一; 山根靖正
Original assignee: Semiconductor Energy Laboratory Co Ltd
Current assignee: Semiconductor Energy Laboratory Co Ltd
Priority date: 2021-03-11
Filing date: 2022-03-03
Publication date: 2023-11-10

Abstract

Provided is a display device with high display quality. Provided is a highly reliable display device. Provided is a display device with low power consumption. A display device is provided which is easy to realize high definition. A display device having both high display quality and high definition is provided. Provided is a display device with high contrast. The display device includes a first pixel including a first pixel electrode, a first EL layer on the first pixel electrode, and a common electrode on the first EL layer, a second pixel including a second pixel electrode, a second EL layer on the second pixel electrode, and a common electrode on the second EL layer, a side surface of the first EL layer and a side surface of the second EL layer having a region in contact with the first insulating layer, the side surface of the first pixel electrode being covered with the first EL layer, and the side surface of the second pixel electrode being covered with the second EL layer.

Description

Display device

Technical Field

One embodiment of the present invention relates to a display device. One embodiment of the present invention relates to a method for manufacturing a display device.

Note that one embodiment of the present invention is not limited to the above-described technical field. Examples of the technical field of one embodiment of the present invention disclosed in the present specification and the like include 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 of these devices, and a manufacturing method of these devices. The semiconductor device refers to all devices capable of operating by utilizing semiconductor characteristics.

Background

In recent years, high definition display panels are demanded. As devices requiring a high-definition display panel, there are, for example, a smart phone, a tablet terminal, a notebook computer, and the like. In addition, a stationary display device such as a television device and a monitor device is also required to have higher definition with higher resolution. As the most demanded high definition device, there is, for example, a device applied to Virtual Reality (VR: virtual Reality) or augmented Reality (AR: augmented Reality).

In addition, as a display device which can be applied to a display panel, a liquid crystal display device, a light-emitting device including a light-emitting element such as an organic EL (Electro Luminescence: electroluminescence) element or a light-emitting diode (LED: light Emitting Diode), an electronic paper which displays by electrophoresis, or the like, is typically given.

For example, the basic structure of an organic EL element (organic electroluminescent element) is a structure in which a layer containing a luminescent organic compound is sandwiched between a pair of electrodes. By applying a voltage between the pair of electrodes, light emission from the light-emitting organic compound can be obtained. Since a display device using the organic EL element does not require a backlight source required for a liquid crystal display device or the like, a thin, lightweight, high-contrast, and low-power display device can be realized. For example, patent document 1 discloses an example of a display device using an organic EL element.

Patent document 2 discloses a display apparatus applied to VR using an organic EL device.

[ Prior Art literature ]

[ patent literature ]

[ patent document 1] Japanese patent application laid-open No. 2002-324673

[ patent document 2] International patent application publication No. 2018/087625

Disclosure of Invention

Technical problem to be solved by the invention

An object of one embodiment of the present invention is to provide a display device with high display quality. An object of one embodiment of the present invention is to provide a display device with high reliability. An object of one embodiment of the present invention is to provide a display device with low power consumption. An object of one embodiment of the present invention is to provide a display device which can easily achieve high definition. One of the objects of the present invention is to provide a display device having both high display quality and high definition. An object of one embodiment of the present invention is to provide a display device with high contrast.

An object of one embodiment of the present invention is to provide a display device having a novel structure or a method of manufacturing a display device. An object of one embodiment of the present invention is to provide a method for manufacturing the display device with high yield. It is an object of one embodiment of the present invention to at least ameliorate at least one of the problems of the prior art.

Note that the description of these objects does not hinder the existence of other objects. Note that one embodiment of the present invention is not required to achieve all of the above objects. Further, other objects than the above can be extracted from the descriptions of the specification, drawings, claims, and the like.

Means for solving the technical problems

One embodiment of the present invention is a display device including a first pixel, a second pixel disposed adjacent to the first pixel, and a first insulating layer, wherein the first pixel includes a first pixel electrode, a first EL layer on the first pixel electrode, and a common electrode on the first EL layer, the second pixel includes a second pixel electrode, a second EL layer on the second pixel electrode, and a common electrode on the second EL layer, a side surface of the first EL layer and a side surface of the second EL layer have regions in contact with the first insulating layer, a side surface of the first pixel electrode is covered with the first EL layer, and a side surface of the second pixel electrode is covered with the second EL layer.

Further, one embodiment of the present invention is a display device including a first pixel, a second pixel disposed adjacent to the first pixel, and a first insulating layer, wherein the first pixel includes a first pixel electrode, a first EL layer on the first pixel electrode, and a common electrode on the first EL layer, the second pixel includes a second pixel electrode, a second EL layer on the second pixel electrode, and a common electrode on the second EL layer, a side surface of the first EL layer and a side surface of the second EL layer have regions in contact with the first insulating layer, an end portion of the first pixel electrode is located inside an end portion of the first EL layer, and an end portion of the second pixel electrode is located inside an end portion of the second EL layer.

Further, one embodiment of the present invention is a display device including a first pixel, a second pixel disposed adjacent to the first pixel, and a first insulating layer, wherein the first pixel includes a first pixel electrode, a first EL layer on the first pixel electrode, and a common electrode on the first EL layer, the second pixel includes a second pixel electrode, a second EL layer on the second pixel electrode, and a common electrode on the second EL layer, a side surface of the first EL layer and a side surface of the second EL layer have regions in contact with the first insulating layer, a side surface of the first pixel electrode is in contact with the first EL layer, and a side surface of the second pixel electrode is in contact with the second EL layer.

In the above structure, it is preferable that the top surface of the first EL layer, the top surface of the second EL layer, and the top surface of the first insulating layer have a region in contact with the common electrode.

In the above structure, it is preferable that the first pixel includes a common layer disposed between the first EL layer and the common electrode, the second pixel includes a common layer disposed between the second EL layer and the common electrode, and the top surface of the first EL layer, the top surface of the second EL layer, and the top surface of the first insulating layer have regions in contact with the common layer.

In the above structure, it is preferable that the first insulating layer has a region protruding upward from at least one of the top surface of the first EL layer and the top surface of the second EL layer when viewed in a cross section of the display device.

In the above structure, it is preferable that at least one of the first EL layer and the second EL layer has a region protruding upward from the top surface of the first insulating layer when viewed in a cross section of the display device.

Further, in the above structure, it is preferable that the top surface of the first insulating layer has a concave curved surface shape when viewed in a cross section of the display device.

Further, in the above structure, it is preferable that the top surface of the first insulating layer has a convex curved surface shape when seen in a cross section of the display device.

Further, one embodiment of the present invention is a display device including a first pixel, a second pixel disposed adjacent to the first pixel, a first insulating layer, and a second insulating layer, the first pixel including a first pixel electrode, a first EL layer over the first pixel electrode, and a common electrode over the first EL layer, the second pixel including a second pixel electrode, a second EL layer over the second pixel electrode, and a common electrode over the second EL layer, a side surface of the first EL layer and a side surface of the second EL layer having a region in contact with the first insulating layer, the second insulating layer being disposed on the first insulating layer and in contact with the first insulating layer and disposed below the common electrode, the first insulating layer including an inorganic material, the second insulating layer including an organic material, a side surface of the first pixel electrode being covered with the first EL layer, and a side surface of the second pixel electrode being covered with the second EL layer.

Further, in the above structure, it is preferable that the top surface of the second insulating layer has a concave curved surface shape when viewed in a cross section of the display device.

Further, in the above structure, it is preferable that the top surface of the second insulating layer has a convex curved surface shape when seen in a cross section of the display device.

Effects of the invention

According to one embodiment of the present invention, a display device with high display quality can be provided. According to one embodiment of the present invention, a highly reliable display device can be provided. According to one embodiment of the present invention, a display device with low power consumption can be provided. According to one embodiment of the present invention, a display device that can easily achieve high definition can be provided. According to one embodiment of the present invention, a display device having both high display quality and high definition can be provided. According to one embodiment of the present invention, a display device with high contrast can be provided.

According to one embodiment of the present invention, a display device having a novel structure or a method of manufacturing a display device can be provided. According to one embodiment of the present invention, a method for manufacturing the display device with high yield can be provided. According to one embodiment of the present invention, at least one of the problems of the prior art may be at least ameliorated.

Note that the description of these effects does not hinder the existence of other effects. Note that one mode of the present invention is not required to have all of the above effects. Effects other than the above can be extracted from the descriptions of the specification, drawings, claims, and the like.

Brief description of the drawings

Fig. 1A is a plan view showing an example of a display device. Fig. 1B to 1D are sectional views showing one example of a display device.

Fig. 2A to 2C are sectional views showing one example of a display device.

Fig. 3A to 3C are sectional views showing one example of a display device.

Fig. 4A to 4F are sectional views showing examples of a manufacturing method of the display device.

Fig. 5A to 5D are sectional views showing examples of a manufacturing method of the display device.

Fig. 6A to 6C are sectional views showing examples of a manufacturing method of the display device.

Fig. 7A to 7C are sectional views showing examples of a manufacturing method of the display device.

Fig. 8A and 8B are cross-sectional views showing examples of a method for manufacturing a display device.

Fig. 9A and 9B are cross-sectional views showing examples of a method for manufacturing a display device.

Fig. 10 is a perspective view showing an example of a display device.

Fig. 11A is a cross-sectional view showing an example of a display device. Fig. 11B and 11C are cross-sectional views showing an example of a transistor.

Fig. 12A and 12B are perspective views showing an example of a display module.

Fig. 13 is a cross-sectional view showing an example of a display device.

Fig. 14 is a cross-sectional view showing an example of a display device.

Fig. 15 is a cross-sectional view showing an example of a display device.

Fig. 16 is a cross-sectional view showing an example of a display device.

Fig. 17A to 17F are diagrams showing structural examples of the light emitting element.

Fig. 18A and 18B are diagrams showing an example of an electronic device.

Fig. 19A to 19D are diagrams showing one example of an electronic device.

Fig. 20A to 20F are diagrams showing one example of an electronic device.

Fig. 21A to 21F are diagrams showing one example of an electronic device.

Fig. 22A and 22B are display photographs of a display panel according to an embodiment.

Fig. 23A to 23C show spectrometry results according to the embodiment.

Fig. 24A to 24C show spectrometry results according to the embodiment.

Modes for carrying out the invention

The embodiments will be described below with reference to the drawings. It is noted that the embodiments may be implemented in a number of different ways, and one skilled in the art can easily understand the fact that the manner and details thereof can be changed into various forms without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the following embodiments.

Note that in the structure of the invention described below, the same reference numerals are used in common in different drawings to denote the same parts or parts having the same functions, and repetitive description thereof will be omitted. In addition, the same hatching is sometimes used when representing portions having the same function, and no reference numerals are particularly attached.

Note that in the drawings described in this specification, the size of each component, the thickness of a layer, and a region may be exaggerated for clarity. Accordingly, the present invention is not limited to the dimensions in the drawings.

In this specification and the like, the "top view" may be replaced by "plan view". In the present specification, the term "planar view" may be replaced by "planar view".

The ordinal numbers such as "first", "second", etc., used in the present specification are attached to avoid confusion of the constituent elements, and are not limited in number.

In this specification and the like, "film" and "layer" may be exchanged with each other. For example, the "conductive layer" or the "insulating layer" may be converted into the "conductive film" or the "insulating film", respectively.

Note that in this specification, the EL layer refers to a layer which is provided between a pair of electrodes of a light-emitting element and includes at least a light-emitting substance (also referred to as a light-emitting layer) or a laminate including a light-emitting layer.

In this specification and the like, a display panel of one embodiment of a display device refers to a panel capable of displaying (outputting) an image or the like on a display surface. Therefore, the display panel is one mode of the output device.

In this specification and the like, a structure in which a connector such as an FPC (Flexible Printed Circuit: flexible printed circuit) or a TCP (Tape Carrier Package: tape carrier package) is mounted On a substrate of a display panel, a structure in which an IC is directly mounted On a substrate by COG (Chip On Glass) or the like is sometimes referred to as a display panel module or a display module, or simply as a display panel or the like.

The light-emitting element according to one embodiment of the present invention may include a layer containing a substance having a high hole-injecting property, a substance having a high hole-transporting property, a substance having a high electron-injecting property, a bipolar substance, or the like.

The light-emitting layer may contain an inorganic compound such as quantum dot or a polymer compound (oligomer, dendrimer, polymer, or the like) respectively, and the layer contains a substance having high hole injection property, a substance having high hole transport property, a substance having high electron injection property, a bipolar substance, or the like. For example, quantum dots can be used as the light emitting material by using them for the light emitting layer.

As the quantum dot material, a colloidal quantum dot material, an alloy type quantum dot material, a Core Shell (Core Shell) type quantum dot material, a Core type quantum dot material, or the like can be used. In addition, a material containing groups of elements of groups 12 and 16, groups 13 and 15, groups 14 and 16 may also be used. Alternatively, quantum dot materials containing elements such as cadmium, selenium, zinc, sulfur, phosphorus, indium, tellurium, lead, gallium, arsenic, aluminum, and the like may be used.

In this specification and the like, a device manufactured using a Metal Mask or an FMM (Fine Metal Mask) is sometimes referred to as a device having a MM (Metal Mask) structure. In this specification and the like, a device manufactured without using a metal mask or an FMM is sometimes referred to as a device having a MML (Metal Mask Less) structure.

In this specification and the like, a structure in which light-emitting layers are formed or applied to light-emitting devices of respective colors (here, blue (B), green (G), and red (R)) is sometimes referred to as a SBS (Side By Side) structure. In this specification and the like, a light-emitting device that can emit white light is sometimes referred to as a white light-emitting device. The white light emitting device can realize a display device that displays in full color by combining with a colored layer (e.g., a color filter).

In addition, the light emitting device can be roughly classified into a single structure and a series structure. The single structure device preferably has the following structure: a light emitting unit is included between a pair of electrodes, and the light emitting unit includes one or more light emitting layers. In order to obtain white light emission, the light emitting layers may be selected so that the light emission of two or more light emitting layers is in a complementary relationship. For example, by placing the light emission color of the first light emission layer and the light emission color of the second light emission layer in a complementary relationship, a structure that emits light in white on the whole light emitting device can be obtained. In addition, the same applies to a light-emitting device including three or more light-emitting layers.

The device of the tandem structure preferably has the following structure: two or more light emitting units are included between a pair of electrodes, and each light emitting unit includes one or more light emitting layers. In order to obtain white light emission, a structure may be employed in which light emitted from the light-emitting layers of the plurality of light-emitting units is combined to obtain white light emission. Note that the structure to obtain white light emission is the same as that in the single structure. In the device having the tandem structure, an intermediate layer such as a charge generation layer is preferably provided between the plurality of light emitting cells.

In addition, in the case of comparing the above-described white light emitting device (single structure or tandem structure) and the light emitting device of the SBS structure, the power consumption of the light emitting device of the SBS structure can be made lower than that of the white light emitting device. Devices intended to reduce power consumption are preferably light emitting devices employing SBS structures. On the other hand, the manufacturing process of the white light emitting device is simpler than that of the SBS structure, and thus the manufacturing cost can be reduced or the manufacturing yield can be improved, so that it is preferable.

(embodiment 1)

In this embodiment mode, a structural example of a display device and a manufacturing method example of the display device according to an embodiment of the present invention are described.

One embodiment of the present invention is a display device including a light-emitting element (also referred to as a light-emitting device). The display device comprises at least two light emitting elements emitting light of different colors. The light emitting elements each include a pair of electrodes and an EL layer between the pair of electrodes. As the light-emitting element, an electroluminescent element such as an organic EL element or an inorganic EL element can be used. In addition, light Emitting Diodes (LEDs) may also be used. The light-emitting element according to one embodiment of the present invention is preferably an organic EL element. Two or more light-emitting elements that emit different colors each include an EL layer including different materials. For example, by including three light emitting elements that emit light of red (R), green (G), or blue (B), respectively, a full-color display device can be realized.

Here, a vapor deposition method using a shadow mask such as a metal mask is known when EL layers are manufactured between light emitting elements of different colors. However, this method is not easy to achieve high definition and high aperture ratio because the shape and position of the island-like organic film are different from the design due to various influences such as an increase in profile of the deposited film caused by precision of the metal mask, misalignment of the metal mask and the substrate, deflection of the metal mask, scattering of vapor, and the like. In addition, there are cases where rubbish is generated due to the material adhering to the metal mask during vapor deposition. Such a dust may cause defective patterns of the light emitting element. In addition, a short circuit may occur due to the garbage. In addition, a cleaning process of the material attached to the metal mask is required. Therefore, sharpness (also referred to as pixel density) is improved in a simulated manner by employing a special pixel arrangement scheme such as Pentile arrangement or the like.

In one embodiment of the present invention, the EL layer is processed into a fine pattern without using a shadow mask such as a metal mask. Therefore, a display device having high definition and high aperture ratio, which have never been realized. In addition, since the EL layers can be manufactured separately, a display device having extremely clear display quality and high contrast can be realized.

Here, for the sake of simplicity, a case where EL layers of light emitting elements of two colors are manufactured separately will be described. First, a first EL film and a first sacrificial film are formed by stacking over the pixel electrode. Next, a resist mask is formed over the first sacrificial film. Next, a part of the first sacrificial film and a part of the first EL film are etched using a resist mask to form a first EL layer and a first sacrificial layer over the first EL layer.

Then, a second EL film and a second sacrificial film are laminated. Next, a portion of the second sacrificial film and a portion of the second EL film are etched using a resist mask to form a second EL layer and a second sacrificial layer over the second EL layer. Then, the pixel electrode is processed using the first sacrificial layer and the second sacrificial layer as masks, and a first pixel electrode overlapping the first EL layer and a second pixel electrode overlapping the second EL layer are formed. The first EL layer and the second EL layer can be formed by the above steps. Finally, the first sacrificial layer and the second sacrificial layer are removed to form a common electrode, thereby forming light emitting elements of two colors respectively.

Further, by repeating the above steps, the EL layers of the light-emitting elements having three or more colors can be formed, respectively, whereby a display device including the light-emitting elements having three or more colors can be realized.

At the end of the EL layer, a step occurs between a region where the pixel electrode and the EL layer are provided and a region where the pixel electrode and the EL layer are not provided. When the common electrode is formed on the EL layer, there is a possibility that the coverage of the common electrode is reduced due to a step at an end portion of the EL layer, and the common electrode is cut off. In addition, the common electrode may be thinned, and the resistance may be increased.

In addition, in the case where the end portion of the pixel electrode is substantially aligned with the end portion of the EL layer and in the case where the end portion of the pixel electrode is located outside the end portion of the EL layer, when the common electrode is formed on the EL layer, there is a possibility that a short circuit occurs between the common electrode and the pixel electrode.

In one embodiment of the present invention, the surface on which the common electrode is provided can be reduced in irregularities by providing an insulating layer between the first EL layer and the second EL layer. Therefore, the coverage of the common electrode at the end portion of the first EL layer and the end portion of the second EL layer can be improved, and good conductivity of the common electrode can be achieved. In addition, short-circuiting of the common electrode and the pixel electrode can be suppressed.

When EL layers of different colors are adjacent to each other, it is difficult to set the interval of the EL layers adjacent to each other to less than 10 μm in a forming method using a metal mask, for example, but it may be reduced to 3 μm or less, 2 μm or less, or 1 μm or less in the above-described method. For example, the interval can be reduced to 500nm or less, 200nm or less, 100nm or less, or even 50nm or less by using an LSI exposure apparatus. Thus, the area of the non-light emitting region which may exist between the two light emitting elements can be greatly reduced, and the aperture ratio can be made close to 100%. For example, an aperture ratio of 50% or more, 60% or more, 70% or more, 80% or more, or even 90% or more and less than 100% may be achieved.

In addition, the pattern on the EL layer itself can be significantly reduced as compared with the case of using a metal mask. In addition, for example, when the EL layers are formed using metal masks, the thicknesses of the center and the end portions of the pattern are different, so that the effective area that can be used as a light emitting region with respect to the entire area of the pattern is reduced. On the other hand, in the above-described manufacturing method, the pattern is formed by performing processing by depositing a film of a uniform thickness, so that the thickness of the pattern can be made uniform, and almost all of its area can be used as a light-emitting area even if a fine pattern is used. Therefore, the above manufacturing method can provide both high definition and high aperture ratio.

In this way, the display device in which the fine light emitting elements are integrally arranged can be realized by the above manufacturing method, and the definition is improved in a pseudo manner without requiring a special pixel arrangement method such as the Pentile method, for example, so that a display device having a definition of 500ppi or more, 1000ppi or more, 2000ppi or more, even 3000ppi or more, or even 5000ppi or more can be realized by using a so-called stripe arrangement in which both R, G and B are arranged in one direction.

A more specific configuration example and a manufacturing method example of a display device according to an embodiment of the present invention will be described below with reference to the drawings.

Structural example 1

Fig. 1A is a schematic plan view of a display device 100 according to an embodiment of the present invention. The display device 100 includes a plurality of light emitting elements 110R that emit red, a plurality of light emitting elements 110G that emit green, and a plurality of light emitting elements 110B that emit blue. In fig. 1A, the light emitting regions of the light emitting elements are denoted by symbols R, G and B for the sake of simplicity in distinguishing the light emitting elements.

The light emitting elements 110R, 110G, and 110B are all arranged in a matrix. The pixel 103 in fig. 1A shows a so-called stripe arrangement in which light emitting elements of the same color are arranged in one direction. Note that the arrangement method of the light emitting elements is not limited to this, and a triangle arrangement, a zigzag arrangement, or the like may be used, or a Pentile arrangement may be used.

As the light-emitting element 110R, the light-emitting element 110G, and the light-emitting element 110B, an EL element such as an OLED (Organic Light Emitting Diode: organic light-emitting diode) or a QLED (Quantum-dot Light Emitting Diode: quantum dot light-emitting diode) is preferably used. Examples of the light-emitting substance included in the EL element include a substance that emits fluorescence (fluorescent material), a substance that emits phosphorescence (phosphorescent material), an inorganic compound (quantum dot material, etc.), a substance that exhibits thermally activated delayed fluorescence (Thermally activated delayed fluorescence: TADF) material), and the like.

Fig. 1B is a schematic cross-sectional view corresponding to the dash-dot lines A1-A2 and the dash-dot lines C1-C2 in fig. 1A, and fig. 1C is a schematic cross-sectional view corresponding to the dash-dot lines B1-B2.

Fig. 1B shows a cross section of the light emitting element 110R, the light emitting element 110G, and the light emitting element 110B. In fig. 1B, a light-emitting element 110R, a light-emitting element 110G, and a light-emitting element 110B are provided over a substrate 101. The light emitting element 110R includes a pixel electrode 111R, EL layer 112R, a common layer 114, and a common electrode 113. The light emitting element 110G includes a pixel electrode 111G, EL layer 112G, a common layer 114, and a common electrode 113. The light emitting element 110B includes a pixel electrode 111B, EL layer 112B, a common layer 114, and a common electrode 113. An insulating layer 131 is provided between the light emitting elements adjacent to each other. Note that, in the following description, the pixel electrode 111 is sometimes referred to as a common reference symbol when the pixel electrode 111R, the pixel electrode 111G, and the pixel electrode 111B are described. Note that, in the description of the common content between the EL layers 112G and 112B of the EL layer 112R, EL, the EL layer 112 may be described by omitting the symbol. Note that, in the description of the common content among the light-emitting element 110R, the light-emitting element 110G, and the light-emitting element 110B, the symbol given to the symbol is omitted in some cases, and the description is made as the light-emitting element 110.

Fig. 2A is an enlarged view of the area surrounded by the rectangular dot-dash line in fig. 1B. Further, fig. 2B is an enlarged view of the area surrounded by the rectangular dot-dash line in fig. 1C.

In this specification and the like, the thicknesses of layers and films in the drawings before enlargement may be shown thick for the sake of simplicity. In addition, the distances between the components included in the display device in the enlarged drawing may be different. For example, in fig. 2A and the like, the distance between the end of the pixel electrode 111R and the end of the EL layer 112R and the distance between the end of the pixel electrode 111B and the end of the EL layer 112B are shown to be wide. The interval between the components of the light-emitting element 110B and the components of the light-emitting element 110R is shown to be wide.

The light emitting element 110R includes an EL layer 112R between the pixel electrode 111R and the common electrode 113. The EL layer 112R contains a light-emitting organic compound that emits at least red light. The light emitting element 110G includes an EL layer 112G between the pixel electrode 111G and the common electrode 113. The EL layer 112G contains a light-emitting organic compound that emits at least green light. The light emitting element 110B includes an EL layer 112B between the pixel electrode 111B and the common electrode 113. The EL layer 112B contains a light-emitting organic compound that emits at least blue light.

In fig. 1B and 1C, the common layer 114 is provided between the pixel electrode 111 and the common electrode 113 of the light emitting element 110. The common layer is a layer common to the light emitting elements. Note that the light-emitting element 110 may not include the common layer 114.

In addition, fig. 1A shows a connection electrode 111C electrically connected to the common electrode 113. The connection electrode 111C is supplied with a potential (for example, an anode potential or a cathode potential) to be supplied to the common electrode 113. The connection electrode 111C is provided outside the display region where the light emitting elements 110R and the like are arranged. In fig. 1A, the common electrode 113 is shown by a broken line.

The connection electrode 111C may be disposed along the outer circumference of the display region. For example, the display region may be provided along one side of the outer periphery of the display region, or may be provided along two or more sides of the outer periphery of the display region. That is, in the case where the top surface of the display region is square, the top surface of the connection electrode 111C may be in the shape of a band, an L-shape, a "" shape (bracket shape), a quadrangle, or the like.

Further, fig. 1B shows a cross section corresponding to the chain line C1-C2 in fig. 1A. In the cross section shown by C1 to C2, a region 130 is provided in which the connection electrode 111C is electrically connected to the common electrode 113. Note that although fig. 1B shows an example in which the common layer 114 is provided between the connection electrode 111C and the common electrode 113, the region 130 may not be provided with the common layer 114 as shown in fig. 1D. In fig. 1D, the connection electrode 111C may be brought into contact with the common electrode 113, further reducing contact resistance.

In the region 130, the common electrode 113 is provided on the connection electrode 111C, and the protective layer 121 is provided so as to cover the common electrode 113.

The EL layer 112R, EL, the layer 112G, and the EL layer 112B each include a layer (light-emitting layer) of an organic compound having light-emitting properties. In addition, the light-emitting layer may contain one or more compounds (host material, auxiliary material) in addition to the light-emitting substance (guest material). As the host material and the auxiliary material, one or more substances having a larger energy gap than the light-emitting substance (guest material) are used. As the host material and the auxiliary material, a compound forming an exciplex is preferably used in combination. In order to form an exciplex efficiently, a compound that easily receives holes (hole-transporting material) and a compound that easily receives electrons (electron-transporting material) are particularly preferably combined.

The light-emitting element may be a low-molecular compound or a high-molecular compound, or may include an inorganic compound (a quantum dot material or the like).

The EL layers 112R, EL, 112G, and 112B may include one or more of an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer in addition to the light-emitting layer.

The pixel electrode 111R, the pixel electrode 111G, and the pixel electrode 111B are provided in each light emitting element. The common electrode 113 is provided as a continuous layer commonly used for the light emitting elements. A conductive film having transparency to visible light is used as either one of the pixel electrode and the common electrode 113, and a conductive film having reflectivity is used as the other. A bottom emission type (bottom emission type) display device can be realized by making each pixel electrode light transmissive and making the common electrode 113 reflective, whereas a top emission type (top emission type) display device can be realized by making each pixel electrode light reflective and making the common electrode 113 light transmissive. In addition, by providing both the pixel electrode and the common electrode 113 with light transmittance, a double-sided emission type (double-sided emission structure) display device can be realized.

A conductive film having reflectivity to visible light is preferably used as the pixel electrode 111. Examples of the conductive film include silver, aluminum, titanium, tantalum, molybdenum, platinum, gold, titanium nitride, and tantalum nitride. In addition, an alloy may be used for the pixel electrode 111. For example, an alloy containing silver may be used. As the alloy containing silver, for example, an alloy containing silver, palladium, and copper can be used. Further, for example, an alloy containing aluminum may be used. Further, these materials may be used to form a laminate of two or more layers.

As the pixel electrode 111, a conductive film having transparency to visible light may be used as a conductive film having reflectivity to visible light. As the conductive material having transparency to visible light, conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide containing gallium, indium tin oxide containing silicon, and indium zinc oxide containing silicon can be used. Further, an oxide of a conductive material having reflectivity for visible light may be used, and the oxide may be formed by oxidizing the surface of the conductive material having reflectivity for visible light. Specifically, for example, titanium oxide may be used. Titanium oxide can be formed by oxidizing the surface of titanium, for example.

By providing an oxide on the surface of the pixel electrode 111, oxidation reaction with the pixel electrode 111 or the like can be suppressed when the EL layer 112 is formed.

Further, by stacking a conductive film having transparency to visible light over a conductive film having reflectivity to visible light as the pixel electrode 111, the conductive film having transparency to visible light can be used as an optical adjustment layer.

By including the optical adjustment layer in the pixel electrode 111, the optical path length can be adjusted. The optical path length of each light-emitting element corresponds to, for example, the sum of the thickness of the optical adjustment layer and the thickness of a layer of the EL layer 112 provided under the film containing the light-emitting compound.

In the light-emitting element, light of a specific wavelength can be enhanced by making the optical path lengths different by using a microcavity structure (a micro resonator structure). Thus, a display device with improved color purity can be realized.

For example, in each light-emitting element, a microcavity structure can be realized by making the thickness of the EL layer 112 different. For example, the following structure may be adopted: the thickness of the EL layer 112R of the light emitting element 110R that emits light having the longest wavelength is made the thickest and the thickness of the EL layer 112B of the light emitting element 110B that emits light having the shortest wavelength is made the thinnest. The thickness of each EL layer may be adjusted in consideration of the wavelength of light emitted from each light-emitting element, the optical characteristics of the layers constituting the light-emitting element, the electrical characteristics of the light-emitting element, and the like.

The top surface and the end of the pixel electrode 111 are covered with the EL layer 112. The end portion of the EL layer 112 is preferably located outside the end portion of the pixel electrode 111.

By covering the top surface and the end portions of the pixel electrode 111 with the EL layer 112, the formation process of the insulating layer 131, and the like can be performed without exposing the pixel electrode 111.

In the etching step when the EL layer 112 or the insulating layer 131 is formed, when the end portion or the like of the pixel electrode 111 is exposed, corrosion may occur in the exposed region. The product resulting from the corrosion of the pixel electrode 111 may be unstable, and may be dissolved in a solution in wet etching, or may be scattered in an atmosphere in dry etching. Since the product is dissolved in the solution of the product and scattered in the atmosphere, for example, the product adheres to the side surface of the EL layer 112, the surface of the substrate 101, or the like, a leak path or the like may be formed between the adjacent plurality of light-emitting elements 110.

The adhesion of the film serving as the EL layer 112, the film serving as the insulating layer 131, or the like may be reduced in the region where the pixel electrode 111 is exposed, and film peeling may occur.

By having a structure in which the top surface and the end portions of the pixel electrode 111 are covered with the EL layer 112, for example, the yield of the light-emitting element 110 can be improved, and the display quality of the light-emitting element 110 can be improved.

An insulating layer 131 is provided between the light emitting elements 110 adjacent to each other. The insulating layer 131 is located between the EL layers 112 included in the light-emitting element 110. In addition, the common electrode 113 is provided on the insulating layer 131.

The insulating layer 131 is provided, for example, between two EL layers 112 emitting different colors. Alternatively, the insulating layer 131 is provided, for example, between two EL layers 112 that emit the same color. Alternatively, a structure in which the insulating layer 131 is provided between two EL layers 112 that emit different colors, instead of being provided between two EL layers 112 that emit the same color, may also be employed.

The insulating layer 131 is provided between the two EL layers 112 in a plan view, for example.

The EL layer 112R, EL layer 112G and the EL layer 112B preferably each have a region in contact with the top surface of the pixel electrode and a region in contact with the side surface of the insulating layer 131. The end portions of the EL layers 112R, EL, 112G, and 112B are preferably in contact with the side surfaces of the insulating layer 131.

By providing the insulating layer 131 between light-emitting elements that emit different colors, the EL layer 112R, EL layer 112G and the EL layer 112G can be suppressed from contacting each other. This makes it possible to suitably prevent unintended light emission due to current flowing through the adjacent two EL layers. This can improve contrast and realize a display device having high display quality.

The insulating layer 131 includes an insulating layer 131a and an insulating layer 131b. The insulating layer 131b is provided so as to contact the side surface of each EL layer 112 included in the light-emitting element 110. In the cross section, the insulating layer 131a is provided on the insulating layer 131b so as to be in contact with the insulating layer 131b to fill the concave portion of the insulating layer 131b.

In fig. 1, the insulating layer 131 is arranged between the EL layers 112 of adjacent pixels so as to have a net shape (also referred to as a lattice shape or a matrix shape) in plan view.

The end portion of the EL layer 112 preferably has a region in contact with the insulating layer 131b.

In addition, the insulating layer 131 may be formed only between pixels emitting different colors without providing the insulating layer 131 between adjacent pixels emitting the same color. In this case, the insulating layer 131 may be arranged to have a stripe shape in a plan view. By disposing the insulating layer 131 in a stripe shape, a space for forming the insulating layer 131 is not required as compared with a case of disposing in a lattice shape, so that the aperture ratio can be improved. When the insulating layer 131 is arranged in a stripe shape, adjacent EL layers of the same color may also be processed into a stripe shape so as to be continuous in the column direction.

The common layer 114 is preferably provided so as to be in contact with the top surface of the EL layer 112, the top surface of the insulating layer 131a, and the top surface of the insulating layer 131 b. The common electrode 113 is preferably disposed in contact with the top surface of the common layer 114. In the case where the light-emitting element 110 does not include the common layer 114, the common electrode 113 is preferably provided so as to be in contact with the top surface of the EL layer 112, the top surface of the insulating layer 131a, and the top surface of the insulating layer 131 b.

Between adjacent light emitting elements, the end portion of the EL layer 112 generates a step due to the region where the EL layer 112 is provided and the region where the EL layer 112 is not provided. The display device according to one embodiment of the present invention includes the insulating layer 131a and the insulating layer 131b to planarize the step, and thus, compared with a case where the common electrode 113 is in contact with the substrate 101 between adjacent light emitting elements, coverage of the common electrode can be improved, and thus, connection failure due to disconnection can be suppressed. Alternatively, the common electrode 113 may be locally thinned by the step, and the increase in resistance may be suppressed.

In one embodiment of the present invention, the formation of the surface roughness of the common electrode 113 can be reduced by providing the insulating layer 131a and the insulating layer 131b between the EL layers 112 disposed adjacently, so that the coverage of the common electrode 113 at the end portion of the EL layer 112 can be improved, and thus good conductivity of the common electrode 113 can be achieved.

In order to improve the flatness of the formation surface of the common electrode 113, the top surface of the insulating layer 131a and the top surface of the insulating layer 131b are preferably substantially aligned with the top surface of the EL layer 112 at the end portion of the EL layer 112. In addition, the top surface of the insulating layer 131 preferably has a flat shape. Note that the top surface of the insulating layer 131a, the top surface of the insulating layer 131b, and the top surface of the EL layer 112 do not need to be aligned. In addition, when the heights of the top surfaces of the EL layers 112 corresponding to different colors are different, the height of the top surface of the insulating layer 131a is preferably substantially identical to the height of the top surface of each EL layer in the vicinity of the EL layer. The height of the top surface of the insulating layer 131b is preferably substantially equal to the height of each EL layer in a region in contact with the side surface of the EL layer.

As shown in fig. 2A and the like, the height of the top surface of the insulating layer 131a is substantially equal to the height of the top surface of the EL layer 112B in the vicinity of the EL layer 112B, and is substantially equal to the height of the top surface of the EL layer 112R in the vicinity of the EL layer 112R. The height of the top surface of the insulating layer 131B is substantially equal to the height of the top surface of the EL layer 112B in a region in contact with the side surface of the EL layer 112B, and is substantially equal to the height of the top surface of the EL layer 112R in a region in contact with the side surface of the EL layer 112R, for example.

The example shown in fig. 2C is different from that of fig. 2B in the shape of the insulating layer 131a and the like. In fig. 2C, the top surface of the insulating layer 131a is lower than the height of the end portion of the EL layer 112.

Fig. 3A and 3B are different from fig. 2A and 2B in the shape of the insulating layer 131a and the like. In fig. 3A and 3B, the top surface of the insulating layer 131a has a shape with a central portion and a depression in the vicinity thereof.

Fig. 3C is different from fig. 2B in the shape of the insulating layer 131a and the like. In fig. 3C, the top surface of the insulating layer 131a has a shape in which a central portion and its vicinity expand.

The insulating layer 131b has a region in contact with the side surface of the EL layer 112 and is used as a protective insulating layer of the EL layer 112. By providing the insulating layer 131b, entry of oxygen, moisture, or constituent elements thereof from the side surface of the EL layer 112 can be suppressed, whereby a highly reliable display device can be realized.

In the cross section, when the width of the insulating layer 131b in the region in contact with the side surface of the EL layer 112 is large, the interval between the EL layers 112 may be large and the aperture ratio may be reduced. When the width of the insulating layer 131b is small, the effect of suppressing the entry of oxygen, moisture, or constituent elements thereof from the side surface of the EL layer 112 may be reduced. The width of the insulating layer 131b in a region in contact with the side surface of the EL layer 112 is preferably 3nm or more and 200nm or less, more preferably 3nm or more and 150nm or less, still more preferably 5nm or more and 100nm or less, still more preferably 10nm or more and 100nm or less, and still more preferably 10nm or more and 50nm or less. By setting the width of the insulating layer 131b within the above range, a display device having a high aperture ratio and high reliability can be realized.

The insulating layer 131b may be an insulating layer including an inorganic material. As the insulating layer 131b, a single layer or stacked layers of aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon oxynitride, silicon nitride oxide, or the like can be used. In particular, alumina is preferable because it has a high selectivity to the EL layer 112 in etching, and has a function of protecting the EL layer 112 in forming the insulating layer 131b described later. In particular, by using an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide formed by an ALD method as the insulating layer 131b, a film with few pinholes can be formed, and the insulating layer 131b having an excellent function of protecting the EL layer 112 can be formed.

Note that in this 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, when referred to as "silicon oxynitride" it refers to a material having a greater oxygen content than nitrogen in its composition, and when referred to as "silicon oxynitride" it refers to a material having a greater nitrogen content than oxygen in its composition.

The insulating layer 131b can be formed by a sputtering method, a chemical vapor deposition (CVD: chemical Vapor Deposition) method, a molecular beam epitaxy (MBE: molecular Beam Epitaxy) method, a pulse laser deposition (PLD: pulsed Laser Deposition) method, an atomic layer deposition (ALD: atomic Layer Deposition) method, or the like. The insulating layer 131b can be preferably formed by an ALD method with good coverage.

The insulating layer 131a provided over the insulating layer 131b has a function of planarizing a concave portion of the insulating layer 131b formed between adjacent light emitting elements. In other words, the insulating layer 131a improves the flatness of the formation surface of the common electrode 113. As the insulating layer 131a, an insulating layer containing an organic material can be suitably used. For example, an acrylic resin, a polyimide resin, an epoxy resin, a polyamide resin, a polyimide amide resin, a siloxane resin, a benzocyclobutene resin, a phenol resin, a precursor of the above-described resin, or the like can be used for the insulating layer 131a. In addition, a photosensitive resin may be used as the insulating layer 131a. The photosensitive resin may use a positive type material or a negative type material.

By forming the insulating layer 131a using a photosensitive resin, the insulating layer 131a can be formed only through an exposure and development process.

The difference in height between the top surface of the insulating layer 131a and the top surface of the EL layer 112 is preferably 0.5 times or less the thickness of the insulating layer 131a, and more preferably 0.3 times or less the thickness of the insulating layer 131a, for example. For example, the insulating layer 131a may be provided so that the top surface of the EL layer 112 is higher than the top surface of the insulating layer 131a. The thickness of the insulating layer 131a is preferably, for example, 0.3 times or more, 0.5 times or more, or 0.7 times or more the thickness of the pixel electrode 111.

The common electrode 113 is provided with a protective layer 121 so as to cover the light emitting elements 110R, 110G, and 110B. The protective layer 121 has a function of preventing impurities such as water from diffusing from above to each light-emitting element.

The protective layer 121 may have, for example, a single-layer structure or a stacked-layer structure including at least an inorganic insulating film. As the inorganic insulating film, for example, an oxide film or a nitride film such as a silicon oxide film, a silicon oxynitride film, a silicon nitride film, an aluminum oxide film, an aluminum oxynitride film, or a hafnium oxide film can be used. Alternatively, a semiconductor material such as indium gallium oxide or indium gallium zinc oxide may be used for the protective layer 121.

As the protective layer 121, a stacked film of an inorganic insulating film and an organic insulating film may be used. For example, it is preferable to sandwich an organic insulating film between a pair of inorganic insulating films. Also, an organic insulating film is preferably used as the planarizing film. Thus, the top surface of the organic insulating film can be flattened, so that the coverage of the inorganic insulating film on the organic insulating film can be improved, and thus the barrier property can be improved. Further, since the top surface of the protective layer 121 is flattened, it is preferable to provide a structure (for example, a color filter, an electrode of a touch sensor, or a lens array) above the protective layer 121, since the influence of the concave-convex shape due to the structure below can be reduced.

Like the common electrode 113, the common layer 114 is provided across the plurality of light emitting elements. The common layer 114 covers the EL layer 112R, EL layer 112G and the EL layer 112B. The manufacturing process can be simplified by including the common layer 114, so that manufacturing costs can be reduced. The common layer 114 and the common electrode 113 may be formed continuously without performing a process such as etching in the manufacturing process. Therefore, the interface between the common layer 114 and the common electrode can be cleaned, and good characteristics can be obtained in the light-emitting element.

The EL layers 112R, EL, 112G and 112B preferably include at least a light-emitting layer containing a light-emitting material that emits one color, for example. The common layer 114 is preferably one or more layers including an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer, for example. In a light-emitting element in which a pixel electrode is used as an anode and a common electrode is used as a cathode, a structure including an electron injection layer or a structure including two of an electron injection layer and an electron transport layer can be used as the common layer 114.

[ production method example 1]

An example of a method for manufacturing a display device according to an embodiment of the present invention is described below with reference to the drawings. Here, the display device 100 shown in the above-described configuration example will be described as an example. Fig. 4A to 7C are schematic cross-sectional views of the following steps of a method for manufacturing a display device.

The thin films (insulating film, semiconductor film, conductive film, and the like) 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, an atomic layer deposition (ALD: atomic Layer Deposition) method, or the like. The CVD method includes a plasma enhanced chemical vapor deposition (PECVD: plasma Enhanced CVD) method, a thermal CVD method, and the like. In addition, as one of the thermal CVD methods, there is a metal organic chemical vapor deposition (MOCVD: metal Organic CVD) method.

The thin film (insulating film, semiconductor film, conductive film, or the like) constituting the display device can be formed by a spin coating method, a dipping method, a spray coating method, an inkjet method, a dispenser method, a screen printing method, an offset printing method, a doctor blade (doctor blade) method, a slit coating method, a roll coating method, a curtain coating method, a doctor blade coating method, or the like.

In addition, when a thin film constituting the display device is processed, the processing may be performed by photolithography or the like. In addition to the above-described method, the thin film may be processed by a nanoimprint method, a sand blast method, a peeling method, or the like. Further, the island-like thin film can be directly formed by a deposition method using a shadow mask such as a metal mask.

Photolithography typically involves two methods. One is a method of forming a resist mask on a thin film to be processed, processing the thin film by etching or the like, and removing the resist mask. Another is a method of processing a photosensitive film into a desired shape by exposing and developing the film after depositing the film.

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 light, krF laser, arF laser, or the like can also be used. In addition, exposure may also be performed using a liquid immersion exposure technique. Furthermore, as the light for exposure, extreme Ultraviolet (EUV) light or X-ray may also be used. In addition, an electron beam may be used instead of the light for exposure. When extreme ultraviolet light, X-rays, or electron beams are used, extremely fine processing can be performed, so that it is preferable. In addition, a photomask is not required when exposure is performed by scanning with an electron beam or the like.

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

[ preparation of substrate 101 ]

As the substrate 101, a substrate having at least heat resistance which can withstand the degree of heat treatment to be performed later can be used. In the case of using an insulating substrate as the substrate 101, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or the like can be used. Further, a single crystal semiconductor substrate or a polycrystalline semiconductor substrate using silicon, silicon carbide, or the like as a material, a compound semiconductor substrate using silicon germanium, or the like as a material, or a semiconductor substrate such as an SOI substrate may be used.

In particular, the substrate 101 is preferably a substrate in which a semiconductor circuit including a semiconductor element such as a transistor is formed over the semiconductor substrate or the insulating substrate. Note that in fig. 4 and the like, the detailed structure of the semiconductor circuit is not shown for the sake of simplicity. The semiconductor circuit preferably constitutes, for example, a pixel circuit, a gate line driver circuit (gate driver), a source line driver circuit (gate driver), or the like. In addition, an arithmetic circuit, a memory circuit, and the like may be configured.

Next, a conductive film to be the pixel electrode 111 is deposited over the substrate 101. Next, a part of the conductive film is etched, and a pixel electrode 111R, a pixel electrode 111G, a pixel electrode 111B, and a connection electrode 111C are formed over the substrate 101 (fig. 4A).

When a conductive film having reflectivity to visible light is used as the pixel electrode, a material having high reflectivity (for example, silver, aluminum, or the like) is preferably used as much as possible in the entire wavelength region of visible light. Thus, not only the light extraction efficiency of the light emitting element but also the color reproducibility can be improved.

[ formation of EL film 112Rf ]

Next, an EL film 112Rf to be an EL layer 112R later is deposited over the pixel electrode 111R, the pixel electrode 111G, and the pixel electrode 111B.

The EL film 112Rf includes at least a film containing a light-emitting compound. In addition, one or more films used as an electron injection layer, an electron transport layer, a charge generation layer, a hole transport layer, or a hole injection layer may be stacked. The EL film 112Rf can be formed by, for example, vapor deposition, sputtering, or inkjet. In addition, not limited thereto, the above-described deposition method may be suitably used.

[ formation of sacrificial film 144 (1) R and sacrificial film 144 (2) R ]

Next, a process of depositing a sacrificial film will be described.

The sacrificial film 144R is a film to be the sacrificial layer 145R. The sacrificial film 144G is a film to be the sacrificial layer 145G. The sacrificial film 144B is a film to be the sacrificial layer 145B. The sacrifice layer 145R, the sacrifice layer 145G, and the sacrifice layer 145B are sometimes collectively referred to as a sacrifice layer 145. The sacrificial layer 145 may have a single-layer structure or a stacked structure of two or more layers.

An example of using a sacrificial layer of a two-layer structure is shown below.

In the example shown below, a stacked structure of the sacrificial film 144 (1) R and the sacrificial film 144 (2) R is used as the sacrificial film 144R, a stacked structure of the sacrificial film 144 (1) G and the sacrificial film 144 (2) G is used as the sacrificial film 144G, and a stacked structure of the sacrificial film 144 (1) B and the sacrificial film 144 (2) B is used as the sacrificial film 144B.

The sacrificial film 144 (1) R is a film to be the sacrificial layer 145 (1) R, and the sacrificial film 144 (2) R is a film to be the sacrificial layer 145 (2) R. The sacrificial film 144 (1) G is a film to be the sacrificial layer 145 (1) G, and the sacrificial film 144 (2) G is a film to be the sacrificial layer 145 (2) G. The sacrificial film 144 (1) B is a film to be the sacrificial layer 145 (1) B, and the sacrificial film 144 (2) B is a film to be the sacrificial layer 145 (2) B.

As a deposition process of the sacrificial film, the sacrificial film 144 (1) R is formed first by covering the EL film 112 Rf. In addition, the sacrificial film 144 (1) R is provided so as to be in contact with the top surface of the connection electrode 111C. Next, a sacrificial film 144 (2) R is formed on the sacrificial film 144 (1) R.

For forming the sacrificial film 144 (1) R and the sacrificial film 144 (2) R, for example, a sputtering method, an ALD method (thermal ALD method, PEALD method), or a vacuum deposition method may be used. The sacrificial film 144 (1) R is preferably formed by an ALD method or a vacuum deposition method, as compared with a sputtering method, by using a formation method with little damage to the EL layer, as the sacrificial film 144 (1) R directly formed on the EL film 112 Rf.

As the sacrificial film 144 (1) R, an inorganic film such as a metal film, an alloy film, a metal oxide film, a semiconductor film, an inorganic insulating film, or the like can be suitably used.

Further, an oxide film may be used as the sacrificial film 144 (1) R. Typically, an oxide film or an oxynitride film of silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, hafnium oxynitride, or the like can be used. As the sacrificial film 144 (1) R, for example, a nitride film can be used. Specifically, a nitride such as silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, or germanium nitride can be used. Such an inorganic material can be formed by a deposition method such as a sputtering method, a CVD method, or an ALD method, and the ALD method is particularly preferably used as the sacrificial film 144 (1) R directly formed on the EL film 112 Rf.

As the sacrificial film 144 (1) R, for example, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, tantalum, or an alloy material containing the metal material can be used. In particular, a low melting point material such as aluminum or silver is preferably used.

Further, as the sacrificial film 144 (1) R, a metal oxide such as indium gallium zinc oxide (in—ga—zn oxide, also referred to as IGZO) may be used. In addition, indium oxide, indium zinc oxide (In-Zn oxide), indium tin oxide (In-Sn oxide), indium titanium oxide (In-Ti oxide), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), or the like can be used. Alternatively, indium tin oxide containing silicon or the like may be used.

In addition, when the element M (M is one or more selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) is used instead of the above gallium, the above material may be used. In particular, M is preferably one or more selected from gallium, aluminum and yttrium.

As the sacrificial film 144 (2) R, the materials described above as usable for the sacrificial film 144 (1) R can be used. One of the materials usable for the sacrificial film 144 (1) R may be selected as the sacrificial film 144 (1) R, and the other may be selected as the sacrificial film 144 (2) R. One or more materials among the materials usable for the sacrificial film 144 (1) R may be selected as the sacrificial film 144 (1) R, and materials other than the material selected for the sacrificial film 144 (1) R may be selected as the sacrificial film 144 (2) R.

As the sacrificial film 144 (1) R, a film having high resistance to etching treatment of each EL film such as the EL film 112Rf, that is, a film having a large etching selectivity can be used. In addition, the sacrificial film 144 (1) R is particularly preferably a film that can be removed by wet etching with little damage to each EL film.

As the sacrificial film 144 (1) R, a material which is soluble in at least a solvent which is chemically stable in the uppermost film of the EL film 112Rf may be used. In particular, a material dissolved in water or alcohol may be suitably used for the sacrificial film 144 (1) R. When the sacrificial film 144 (1) R is deposited, it is preferable that the sacrificial film 144 (1) R is coated in a wet deposition method in a state dissolved in a solvent such as water or alcohol, and then a heating treatment for evaporating the solvent is performed. In this case, the solvent can be removed at a low temperature in a short time by performing the heat treatment under a reduced pressure atmosphere, and thus thermal damage to the EL film 112Rf can be reduced, which is preferable.

As a wet deposition method for forming the sacrificial film 144 (1) R, there are spin coating, dipping, spraying, inkjet, dispenser, screen printing, offset printing, doctor blade (doctor blade), slit coating, roll coating, curtain coating, doctor blade coating, and the like.

As the sacrificial film 144 (1) R, an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerol, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin can be used.

As the sacrificial film 144 (2) R, a film having a relatively large selectivity as that of the sacrificial film 144 (1) R can be used.

It is particularly preferable to use an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide formed by an ALD method as the sacrificial film 144 (1) R, and to use an indium-containing metal oxide such as indium gallium zinc oxide (also referred to as In-Ga-Zn oxide or IGZO) formed by a sputtering method as the sacrificial film 144 (2) R.

The sacrificial film 144 (2) R may be an organic film that can be used for the EL film 112Rf or the like. For example, the same film as the organic film used for the EL film 112Rf, the EL film 112Gf, or the EL film 112Bf may be used as the sacrificial film 144 (2) R. By using such an organic film, a deposition device can be used in common with the EL film 112Rf or the like, so that it is preferable. In addition, the sacrificial layer 145 (2) R can be removed while etching the EL film 112Rf or the like, whereby simplification of the process can be achieved.

For example, when dry etching using a gas containing fluorine (also referred to as a fluorine-based gas) for etching the sacrificial film 144 (1) R, silicon nitride, silicon oxide, tungsten, titanium, molybdenum, tantalum nitride, an alloy containing molybdenum and niobium, an alloy containing molybdenum and tungsten, or the like can be used for the sacrificial film 144 (2) R. Here, as a film having a relatively large etching selectivity (that is, a relatively low etching rate) with respect to the dry etching using the fluorine-based gas, a metal oxide film such as IGZO or ITO may be used, and the film may be used for the sacrificial film 144 (1) R.

[ formation of resist mask 143a ]

Next, a resist mask 143a is formed over the sacrificial film 144 (2) R (fig. 4B). Note that fig. 4B shows an example in which deposition of the EL film 112Rf is not performed in the region 130. In deposition of the EL film 112Rf, a metal mask may be used when masking the region 130. Since the metal mask used at this time does not need to cover the pixel region of the display portion, a high-definition mask is not required.

As the resist mask 143a, a resist material containing a photosensitive resin such as a positive resist material or a negative resist material can be used.

Here, when the resist mask 143a is formed over the sacrificial film 144 (2) R, if a defect such as a pinhole is present in the sacrificial film 144 (2) R, the EL film 112Rf may be dissolved by the solvent of the resist material. By using an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide formed by an ALD method as the sacrificial film 144 (1) R, a film with few pinholes can be formed, and the occurrence of the above-described defects can be prevented.

[ etching of sacrificial film 144 (1) R and sacrificial film 144 (2) ] R

Next, portions of the sacrificial film 144 (2) R and the sacrificial film 144 (1) R not covered with the resist mask 143a are removed by etching, thereby forming island-shaped or stripe-shaped sacrificial layers 145 (1) R and sacrificial layers 145 (2) R. Here, the sacrifice layer 145 (1) R and the sacrifice layer 145 (2) R are formed on the pixel electrode 111R and on the connection electrode 111C.

Here, it is preferable that a part of the sacrificial film 144 (2) R is removed by etching using the resist mask 143a to form the sacrificial layer 145 (2) R, and then the resist mask 143a is removed to etch the sacrificial film 144 (1) R using the sacrificial layer 145 (2) R as a hard mask. In etching the sacrificial film 144 (2) R, etching conditions having a high selectivity to the sacrificial film 144 (1) R are preferably employed. The etching for forming the hard mask may be wet etching or dry etching, and the reduction of the pattern may be suppressed by using dry etching. For example, when an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide formed by an ALD method is used as the sacrificial film 144 (1) R, and an indium-containing metal oxide such as indium gallium zinc oxide (also referred to as in—ga—zn oxide or IGZO) formed by a sputtering method is used as the sacrificial film 144 (2) R, the sacrificial film 144 (2) R formed by the sputtering method is etched to form a hard mask.

The removal of the resist mask 143a may be performed by wet etching or dry etching. In particular, the resist mask 143a is preferably removed by dry etching (also referred to as plasma ashing) using an oxygen gas for an etching gas.

By etching the sacrificial film 144 (1) R with the sacrificial layer 145 (2) R as a hard mask, the resist mask 143a can be removed in a state where the EL film 112Rf is covered with the sacrificial film 144 (1) R. In particular, the electrical characteristics may be adversely affected when the EL film 112Rf is exposed to oxygen, and therefore, this is preferable when etching using an oxygen gas such as plasma ashing is performed.

Next, the sacrificial layer 145 (2) R is used as a mask, and the sacrificial film 144 (1) R is removed by etching to form an island-shaped or stripe-shaped sacrificial layer 145 (1) R. Note that in the method for manufacturing a display device according to one embodiment of the present invention, either one of the sacrifice layer 145 (1) R and the sacrifice layer 145 (2) R may not be used.

[ etching of EL film 112Rf ]

Next, a portion of the EL film 112Rf not covered with the sacrifice layer 145 (1) R is removed by etching, thereby forming an island-like or band-like EL layer 112R.

It is preferable to use dry etching using an etching gas containing no oxygen as a main component in etching the EL film 112 Rf. This suppresses deterioration of the EL film 112Rf, thereby realizing a highly reliable display device. As a non-return Examples of the etching gas containing oxygen as a main component include CF ₄ 、C ₄ F ₈ 、SF ₆ 、CHF ₃ 、Cl ₂ 、H ₂ O、BCl ₃ Or a rare gas such as He. In addition, a mixed gas of the above gases and a diluent gas containing no oxygen may be used as the etching gas. Here, a part of the sacrificial layer 145 (1) R may be removed when etching the EL film 112 Rf. For example, in the case where an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide formed by an ALD method is used as a lower layer and an indium-containing metal oxide such as indium gallium zinc oxide (also referred to as in—ga—zn oxide or IGZO) formed by a sputtering method is used as an upper layer In the sacrificial film 144 (1) R having a two-layer structure, the upper layer may be etched In etching of the EL film 112 Rf.

Note that etching of the EL film 112Rf is not limited to the above method, and may be performed by dry etching using other gases or by wet etching.

In addition, when dry etching using an etching gas containing oxygen gas or oxygen gas is used for etching the EL film 112Rf, the etching rate can be increased. Thus, since etching can be performed under low power conditions while maintaining the etching rate at a sufficient rate, damage caused by etching can be reduced. In addition, the adhesion of reaction products and other defects occurring during etching can be suppressed. For example, an etching gas in which an oxygen gas is added to an etching gas containing no oxygen as the main component may be used.

[ formation of the EL layer 112G, EL layer 112B ]

Next, an EL film 112Gf to be an EL layer 112G is deposited over the sacrificial layer 145 (1) R, over the pixel electrode 111G, and over the pixel electrode 111B. For the EL film 112Gf, the description of the EL film 112Rf can be referred to.

Next, a sacrificial film 144 (1) G is deposited on the EL film 112Gf. The description of the sacrificial film 144 (1) R can be referred to as the sacrificial film 144 (1) G.

Next, a sacrificial film 144 (2) G is deposited on the sacrificial film 144 (1) G. The description of the sacrificial film 144 (2) R can be referred to as the sacrificial film 144 (2) G.

Next, a resist mask 143b is formed over the sacrificial film 144 (2) G (fig. 4C).

Next, a sacrifice layer 145 (1) G, a sacrifice layer 145 (2) G, and an EL layer 112G are formed (fig. 4D). For the formation of the sacrifice layer 145 (1) G, the sacrifice layer 145 (2) G, and the EL layer 112G, reference can be made to the formation of the sacrifice layer 145 (1) R, the sacrifice layer 145 (2) R, and the EL layer 112R.

Next, an EL film 112Bf to be an EL layer 112B is deposited over the sacrifice layer 145 (2) R, the sacrifice layer 145 (2) G, and the pixel electrode 111B. For the EL film 112Bf, the description of the EL film 112Rf can be referred to.

Next, a sacrificial film 144 (1) B is deposited on the EL film 112Bf. The description of the sacrificial film 144 (1) R can be referred to as the sacrificial film 144 (1) B.

Next, a sacrificial film 144 (2) B is deposited on the sacrificial film 144 (1) B. The description of the sacrificial film 144 (2) R can be referred to as the sacrificial film 144 (2) B.

Next, a resist mask 143c is formed over the sacrificial film 144 (2) B (fig. 4D).

Next, a sacrifice layer 145 (1) B, a sacrifice layer 145 (2) B, and an EL layer 112B are formed (fig. 4E). For the formation of the sacrifice layer 145 (1) B, the sacrifice layer 145 (2) B, and the EL layer 112B, reference can be made to the formation of the sacrifice layer 145 (1) R, the sacrifice layer 145 (2) R, and the EL layer 112R.

Fig. 4F is an enlarged view of the area surrounded by the rectangular dot-dash line in fig. 4E.

In this specification and the like, the thicknesses of layers and films in the drawings before enlargement may be shown thick for the sake of simplicity. In addition, the distances between the components included in the display device in the enlarged drawing may be different. For example, in fig. 4F, the distance between the end of the pixel electrode 111 and the end of the EL layer 112 is shown to be wide. The interval between the components of the light-emitting element 110B and the components of the light-emitting element 110R is shown to be wide.

Next, the sacrificial layer 145 (2) R, the sacrificial layer 145 (2) G, and the sacrificial layer 145 (2) B (hereinafter, collectively referred to as the sacrificial layer 145 (2)) are removed using etching or the like (fig. 5A). The sacrificial layer 145 (2) is preferably etched using a condition having a high selectivity to the sacrificial layer 145 (1) R, the sacrificial layer 145 (1) G, and the sacrificial layer 145 (1) B (hereinafter, collectively referred to as the sacrificial layer 145 (1)). Note that the sacrifice layer 145 (2) may not be removed.

[ formation of insulating layer 131 ]

Next, an insulating film 131bf serving as an insulating layer 131B is formed (fig. 5B). The insulating film 131bf preferably uses a film containing an inorganic material. For example, a single layer or a stacked layer of aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon oxynitride, silicon nitride oxide, or the like can be used as the insulating film 131 bf.

The insulating film 131bf may be formed by a sputtering method, a Chemical Vapor Deposition (CVD) method, a Molecular Beam Epitaxy (MBE) method, a Pulsed Laser Deposition (PLD) method, an Atomic Layer Deposition (ALD) method, or the like. The insulating film 131bf can be suitably formed by an ALD method having good coverage.

As the insulating film 131bf, a single layer or stacked layers of aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon oxynitride, silicon nitride oxide, or the like can be used. In particular, alumina is preferable because it has a high selectivity to the EL layer 112 in etching, and has a function of protecting the EL layer 112 in forming the insulating layer 131b described later.

The insulating film 131bf is formed by the ALD method, so that a film with few pinholes can be formed, and the insulating layer 131b having an excellent function of protecting the EL layer 112 can be formed.

The deposition temperature of the insulating film 131bf is preferably a temperature lower than the heat-resistant temperature of the EL layer 112.

Here, aluminum oxide is formed as the insulating film 131bf by an ALD method. The temperature at the time of forming the insulating film 131bf by the ALD method is preferably 60 ℃ or higher and 150 ℃ or lower, more preferably 70 ℃ or higher and 115 ℃ or lower, and still more preferably 80 ℃ or higher and 100 ℃ or lower. By forming the insulating film 131bf at such a temperature, a dense insulating film can be obtained, and damage to the EL layer 112 can be reduced.

Next, an insulating film 131af which becomes the insulating layer 131a is formed (fig. 5C). The insulating film 131af is provided so as to be fitted into the concave portion of the insulating film 131 bf. The insulating film 131af is provided so as to cover the sacrificial layer 145 (1), the EL layer 112, and the pixel electrode 111. The insulating film 131af is preferably a planarizing film.

As the insulating film 131af, an insulating film containing an organic material is preferably used, and as the organic material, a resin is preferably used.

Examples of the material that can be used for the insulating film 131af include an acrylic resin, a polyimide resin, an epoxy resin, a polyamide resin, a polyimide amide resin, a siloxane resin, a benzocyclobutene resin, a phenol resin, a precursor of the above-described resin, and the like. In addition, a photosensitive resin may be used as the insulating film 131 af. The photosensitive resin may use a positive type material or a negative type material.

By forming the insulating film 131af using a photosensitive resin, the insulating film 131af can be formed only by an exposure and development process, and damage to each layer constituting the light-emitting element 110, particularly damage to an EL layer, can be reduced.

As shown in fig. 5C, the insulating film 131af may have gentle irregularities reflecting the irregularities of the surface to be formed. Alternatively, as shown in fig. 5D, the influence of the irregularities on the surface to be formed on the insulating film 131af may be small, and the flatness may be higher than that in fig. 5C.

Next, an insulating layer 131a is formed. Here, by using a photosensitive resin as the insulating film 131af, the insulating layer 131a can be formed without providing an etching mask such as a resist mask or a hard mask. In addition, since the photosensitive resin can be processed only through the exposure and development steps, the insulating layer 131a can be formed without using a dry etching method or the like. Thus, simplification of the process can be achieved. Further, damage to the EL layer due to etching of the insulating film 131af can be reduced. Further, a portion of the top of the insulating layer 131a may be etched to adjust the surface height.

The insulating layer 131a may be formed by etching the top surface of the insulating film 131af substantially uniformly. The process of uniformly etching and planarizing in this manner is also called etching back.

In forming the insulating layer 131a, an exposure and development process and an etching back process may be used in combination.

An example of a method for forming the insulating layer 131a is described with reference to fig. 6A to 6C. In the example of fig. 6A, a photosensitive resin is used as the insulating film 131af, and the insulating film 131af is processed by an exposure and development step to form an insulating layer 131ap. Fig. 6B is an enlarged view of the area surrounded by the rectangular dot-dash line in fig. 6A. The insulating layer 131a shown in fig. 6C can be formed by further etching the insulating layer 131ap shown in fig. 6B.

Note that the insulating layer 131ap shown in fig. 6B may be used as the insulating layer 131a, and in this case, the light-emitting element 110 may have a structure in which a sacrificial layer 145 (1) remains between the insulating layer 131a and the EL layer 112.

Next, etching of the insulating film 131bf and the sacrificial layer 145 (1) is performed (fig. 7A). In this case, a method of preventing damage to the EL layers 112R, EL, 112G and 112B as much as possible is preferably used. Thereby, the insulating layer 131B covering the side surfaces of the EL layer 112R, EL layer 112G and the EL layer 112B is formed. Fig. 7B is an enlarged view of the area surrounded by the rectangular dot-dash line in fig. 7A.

By using the same material for the insulating film 131bf and the sacrificial layer 145 (1), etching may be performed simultaneously, which may simplify the process.

The insulating film 131bf may be etched by dry etching or wet etching. The etching may be performed by ashing using oxygen plasma or the like. Further, as etching of the insulating film 131bf, chemical mechanical polishing (CMP: chemical Mechanical Poliching) may be used.

Note that damage to the EL layer 112 by etching is preferably suppressed when the insulating film 131bf is etched. Therefore, for example, a material having a high etching selectivity to the EL layer 112 is preferably used as the insulating film 131bf.

By using an inorganic material for the insulating film 131bf, the selection ratio with respect to the EL layer 112 may be increased. As the insulating layer 131b, a single layer or stacked layers of aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon oxynitride, silicon nitride oxide, or the like can be used. In particular, alumina is preferable because it has a high selectivity to the EL layer 112 in etching, and has a function of protecting the EL layer 112 in forming the insulating layer 131b described later. In particular, by using an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide formed by an ALD method as the insulating layer 131b, a film with few pinholes can be formed, and the insulating layer 131b having an excellent function of protecting the EL layer 112 can be formed.

When the insulating film 131af and the insulating film 131bf are formed, the height of the top surface thereof can be adjusted according to the etching amount. Here, the etching amount is preferably adjusted so that the insulating layer 131b covers the side surface of the EL layer 112. In particular, the etching amount is preferably adjusted so that the insulating layer 131b covers the side surface of the light-emitting layer included in the EL layer 112.

Further, the flatness of the surface of the insulating film 131af containing an organic material may vary depending on the irregularities of the surface to be formed and the density of the pattern formed on the surface to be formed. Further, the flatness of the insulating film 131af may vary depending on the viscosity or the like of a material used for the insulating film 131 af. For example, the thickness of the insulating film 131af in the region not overlapping the EL layer 112 may be smaller than the thickness of the insulating film 131af in the region overlapping the EL layer 112 on the EL layer 112. In this case, for example, when etching back the insulating film 131af, the height of the top surface of the insulating layer 131 may be lower than the height of the top surface of the sacrificial layer 145 (1).

In addition, the insulating film 131af may have a concave curved surface shape (depressed shape), a convex curved surface shape (expanded shape), or the like in a region between the plurality of EL layers 112.

[ formation of common layer 114 ]

Next, a common layer 114 is formed. Note that in the case of a structure including no common layer 114, a common electrode 113 may be formed so as to cover the EL layer 112R, EL, the layer 112G, and the EL layer 112B.

[ formation of common electrode 113 ]

Next, the common electrode 113 is formed on the common layer 114. The common electrode 113 can be formed by, for example, a sputtering method, a vacuum evaporation method, or the like. Note that when the common layer 114 is not provided over the connection electrode 111C, masking may be performed using a metal mask over the connection electrode 111C in deposition of the common layer 114. Since the metal mask used at this time does not need to cover the pixel region of the display portion, a high-definition mask is not required.

Through the above steps, the light-emitting element 110R, the light-emitting element 110G, and the light-emitting element 110B can be manufactured.

[ formation of protective layer 121 ]

Next, a protective layer 121 is formed over the common electrode 113 (fig. 7C). The sputtering method, the PECVD method, or the ALD method is preferably used in depositing the inorganic insulating film for the protective layer 121. In particular, the ALD method is preferable because it has a defect that the step coverage is good and pinholes or the like are not easily generated. In addition, since a film can be uniformly formed in a desired region, an inkjet method is preferably used in depositing an organic insulating film.

Through the above steps, the display device 100 shown in fig. 1A can be manufactured.

[ modification of Structure example 1 ]

Fig. 8A and 8B show a modified example of the structure of the display device 100 shown in fig. 1.

The display device 100 shown in fig. 8A is different from that of fig. 1B in the shape of an insulating layer 131a, an insulating layer 131B, and the like. Fig. 8B is an enlarged view of the area surrounded by the rectangular dot-dash line in fig. 8A.

In fig. 8A and 8B, the display device 100 includes a sacrificial layer 145 (1) between the insulating layer 131B and the pixel electrode 111. Such a structure can be obtained by processing the insulating layer 131ap so as to leave a region covering the sacrifice layer 145 (1) in the structure shown in fig. 6B.

Fig. 9A and 9B are different from fig. 8B in the shape of the insulating layer 131a, the insulating layer 131B, and the like.

The structure shown in fig. 9A can be obtained by using the insulating layer 131ap shown in fig. 6B as the insulating layer 131 a. Further, for example, the insulating layer 131a may be provided so that the top surface of the insulating layer 131a is higher than the top surface of the light-emitting layer included in the EL layer 112.

The structure shown in fig. 9B shows an example in which the end portion of the EL layer 112 has no step. By having the structure shown in fig. 9B, the distance between the EL layers 112 included in each of the different light-emitting elements 110 can be reduced, and the aperture ratio of the light-emitting element 110 can be increased in some cases.

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

(embodiment 2)

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

The display device of the present embodiment may be a high-resolution display device or a large-sized display device. Therefore, for example, the display device of the present embodiment can be used as a display portion of: electronic devices having a large screen such as a television set, a desktop or notebook type personal computer, a display for a computer or the like, a digital signage, a large-sized game machine such as a pachinko machine, and the like; a digital camera; a digital video camera; a digital photo frame; a mobile telephone; a portable game machine; a smart phone; a wristwatch-type terminal; a tablet terminal; a portable information terminal; and a sound reproducing device.

[ structural example of display device ]

Fig. 10 shows a perspective view of the display device 400A, and fig. 11A shows a cross-sectional view of the display device 400A.

The display device 400A has a structure in which a substrate 452 and a substrate 451 are bonded. In fig. 10, the substrate 452 is shown in dashed lines.

The display device 400A includes a display portion 462, a circuit 464, a wiring 465, and the like. Fig. 10 shows an example in which an IC473 and an FPC472 are mounted in the display device 400A. Accordingly, the structure shown in fig. 10 may also be referred to as a display module including the display device 400A, IC (integrated circuit) and an FPC.

As the circuit 464, for example, a scan line driver circuit can be used.

The wiring 465 has a function of supplying signals and power to the display portion 462 and the circuit 464. The signal and power are input to the wiring 465 from the outside through the FPC472 or input to the wiring 465 from the IC 473.

Fig. 10 shows an example in which an IC473 is provided over a substrate 451 by COG (Chip On Glass) or COF (Chip On Film) method. As the IC473, for example, an IC including a scanning line driver circuit, a signal line driver circuit, or the like can be used. Note that the display device 400A and the display module are not necessarily provided with ICs. Further, the IC may be mounted on the FPC by COF method or the like.

Fig. 11A shows an example of a cross section of a portion of a region including FPC472, a portion of circuit 464, a portion of display portion 462, and a portion of a region including an end portion of display device 400A.

The display device 400A shown in fig. 11A includes, between a substrate 451 and a substrate 452, a transistor 201, a transistor 205, a light-emitting element 430A that emits red light, a light-emitting element 430b that emits green light, a light-emitting element 430c that emits blue light, and the like.

As the light-emitting elements 430a, 430b, and 430c, the light-emitting elements illustrated in embodiment mode 1 can be used.

Here, when a pixel of a display device includes three sub-pixels including light emitting elements which emit different colors from each other, the three sub-pixels include three colors of red (R), green (G), and blue (B), three colors of yellow (Y), cyan (C), and magenta (M), and the like. When four of the above-described sub-pixels are included, four color sub-pixels of red (R), green (G), blue (B), and white (W), four color sub-pixels of R, G, B, and Y, and the like can be given as the four sub-pixels.

The protective layer 410 is bonded to the substrate 452 by an adhesive layer 442. As the sealing of the light emitting element, a solid sealing structure, a hollow sealing structure, or the like can be used. In fig. 11A, a space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 is filled with an inert gas (nitrogen, argon, or the like), and a hollow sealing structure is used. The adhesive layer 442 may overlap with the light emitting element. In addition, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 may be filled with a resin different from the adhesive layer 442.

In an opening portion provided in the insulating layer 214 so as to expose the top surface of the conductive layer 222b included in the transistor 205, a conductive layer 418a, a conductive layer 418b, and a portion of the conductive layer 418c are formed along the bottom surface and the side surface of the opening portion. Conductive layers 418a, 418b, and 418c are each connected to a conductive layer 222b included in the transistor 205 through an opening provided in the insulating layer 214. The pixel electrode includes a material that reflects visible light, and the counter electrode includes a material that transmits visible light. In addition, the conductive layer 418a, the conductive layer 418b, and other portions of the conductive layer 418c are provided over the insulating layer 214.

The pixel electrode 411a, the pixel electrode 411b, and the pixel electrode 411c are provided over the conductive layer 418a, the conductive layer 418b, and the conductive layer 418 c. The insulating layer 414 may be provided between the conductive layer 418a and the conductive layer 411a included in the light-emitting element 430a, between the conductive layer 418b and the conductive layer 411b included in the light-emitting element 430b, and between the conductive layer 418c and the conductive layer 411c included in the light-emitting element 430 c.

As shown in fig. 11A, insulating layers 421 may be provided between the EL layer 416a included in the light-emitting element 430a, the EL layer 416b included in the light-emitting element 430b, and the EL layer 416c included in the light-emitting element 430 c.

As the pixel electrode 411a, the pixel electrode 411b, and the pixel electrode 411c, the pixel electrode 111 shown in the above embodiment mode can be used.

The region between the light emitting element 430a and the light emitting element 430b and over the insulating layer 214, and the region between the light emitting element 430b and the light emitting element 430c and over the insulating layer 214 are each provided with an insulating layer 421. As the insulating layer 421, the insulating layer 131 shown in the above embodiment mode can be referred to.

The light emitting element emits light to the substrate 452 side. The substrate 452 is preferably made of a material having high transmittance to visible light.

Both the transistor 201 and the transistor 205 are provided over the substrate 451. These transistors may be formed using the same material and the same process.

An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided in this order over the substrate 451. A part of the insulating layer 211 serves as a gate insulating layer of each transistor. A part of the insulating layer 213 serves as a gate insulating layer of each transistor. The insulating layer 215 is provided so as to cover the transistor. The insulating layer 214 is provided so as to cover the transistor, and is used as a planarizing layer. The number of gate insulating layers and the number of insulating layers covering the transistor are not particularly limited, and may be one or two or more.

Preferably, a material which is not easily diffused by impurities such as water and hydrogen is used for at least one of insulating layers covering the transistor. Thereby, the insulating layer can be used as a barrier layer. By adopting such a structure, diffusion of impurities into the transistor from the outside can be effectively suppressed, so that the reliability of the display device can be improved.

An inorganic insulating film is preferably used for the insulating layer 211, the insulating layer 213, and the insulating layer 215. As the inorganic insulating film, for example, a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum nitride film, or the like can be used. Further, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, a neodymium oxide film, or the like can be used. Further, two or more of the insulating films may be stacked.

Here, the barrier property of the organic insulating film is lower than that of the inorganic insulating film in many cases. Therefore, the organic insulating film preferably includes an opening near an end of the display device 400A. Thereby, entry of impurities from the end portion of the display device 400A through the organic insulating film can be suppressed. In addition, the organic insulating film may be formed such that an end portion thereof is positioned inside an end portion of the display device 400A so that the organic insulating film is not exposed to the end portion of the display device 400A.

The insulating layer 214 used as the planarizing layer is preferably an organic insulating film. As a material that can be used for the organic insulating film, for example, an acrylic resin, a polyimide resin, an epoxy resin, a polyamide resin, a polyimide amide resin, a siloxane resin, a benzocyclobutene resin, a phenol resin, a precursor of the above-described resin, or the like can be used.

In the region 228 shown in fig. 11A, an opening is formed in a two-layer structure in which the insulating layer 214 and the insulating layer 421b over the insulating layer 214 are stacked. The insulating layer 421b can be formed using the same material as the insulating layer 421. The insulating layer 421b is formed by, for example, the same process as the insulating layer 421. A protective layer 410 is formed so as to cover the opening. By using an inorganic layer as the protective layer 410, even in the case of using an organic insulating film as the insulating layer 214, entry of impurities into the display portion 462 from the outside through the insulating layer 214 can be suppressed. Thereby, the reliability of the display device 400A can be improved.

Transistor 201 and transistor 205 include: a conductive layer 221 serving as a gate electrode; an insulating layer 211 serving as a gate insulating layer; a conductive layer 222a functioning as one of a source electrode and a drain electrode; a conductive layer 222b serving as the other of the source electrode and the drain electrode; a semiconductor layer 231; an insulating layer 213 serving as a gate insulating layer; and a conductive layer 223 serving as a gate electrode. Here, a plurality of layers obtained by processing the same conductive film are indicated by the same hatching. The insulating layer 211 is located between the conductive layer 221 and the semiconductor layer 231. The insulating layer 213 is located between the conductive layer 223 and the semiconductor layer 231.

The transistor structure included in the display device of this embodiment is not particularly limited. For example, a planar transistor, an interleaved transistor, an inverted interleaved transistor, or the like can be employed. In addition, the transistors may have either a top gate structure or a bottom gate structure. Alternatively, a gate electrode may be provided above and below the semiconductor layer forming the channel.

As the transistor 201 and the transistor 205, a structure in which a semiconductor layer forming a channel is sandwiched between two gates is adopted. Further, two gates may be connected to each other, and the same signal may be supplied to the two gates to drive the transistor. Alternatively, the threshold voltage of the transistor can be controlled by applying a potential for controlling the threshold voltage to one of the two gates and applying a potential for driving to the other gate.

The crystallinity of the semiconductor material used for the transistor is not particularly limited, and an amorphous semiconductor or a semiconductor having crystallinity (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor in which a part thereof has a crystalline region) can be used. It is preferable to use a semiconductor having crystallinity because deterioration in characteristics of a transistor can be suppressed.

The semiconductor layer of the transistor preferably uses a metal oxide (oxide semiconductor). That is, the display device of this embodiment mode preferably uses a transistor including a metal oxide in a channel formation region (hereinafter, an OS transistor). In addition, the semiconductor layer of the transistor may contain silicon. Examples of the silicon include amorphous silicon and crystalline silicon (low-temperature polycrystalline silicon, single crystal silicon, and the like).

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 or tin.

In particular, as the semiconductor layer, an oxide (IGZO) containing indium (In), gallium (Ga), and zinc (Zn) is preferably used.

When an In-M-Zn oxide is used for the semiconductor layer, the atomic ratio of In the In-M-Zn oxide is preferably equal to or greater than the atomic ratio of M. The atomic number ratio of the metal elements of such an In-M-Zn oxide may be In: m: zn=1: 1:1 or the vicinity thereof, in: m: zn=1: 1:1.2 composition at or near, in: m: zn=2: 1:3 or the vicinity thereof, in: m: zn=3: 1:2 or the vicinity thereof, in: m: zn=4: 2:3 or the vicinity thereof, in: m: zn=4: 2:4.1 or the vicinity thereof, in: m: zn=5: 1:3 or the vicinity thereof, in: m: zn=5: 1:6 or the vicinity thereof, in: m: zn=5: 1:7 or the vicinity thereof, in: m: zn=5: 1:8 or the vicinity thereof, in: m: zn=6: 1:6 or the vicinity thereof, in: m: zn=5: 2:5 or the vicinity thereof, and the like. Further, the composition in the vicinity includes a range of ±30% of a desired atomic number ratio.

When the atomic ratio is expressed as In: ga: zn=4: 2:3 or its vicinity, including the following: when the atomic ratio of In is 4, the atomic ratio of Ga is 1 to 3, and the atomic ratio of Zn is 2 to 4. Note that, when the atomic ratio is expressed as In: ga: zn=5: 1:6 or its vicinity, including the following: when the atomic ratio of In is 5, the atomic ratio of Ga is more than 0.1 and 2 or less, and the atomic ratio of Zn is 5 or more and 7 or less. Note that, when the atomic ratio is expressed as In: ga: zn=1: 1:1 or its vicinity, including the following: when the atomic ratio of In is 1, the atomic ratio of Ga is more than 0.1 and 2 or less, and the atomic ratio of Zn is more than 0.1 and 2 or less.

The transistor included in the circuit 464 and the transistor included in the display portion 462 may have the same structure or may have different structures. The plurality of transistors included in the circuit 464 may have the same structure or may have two or more different structures. In the same manner, the plurality of transistors included in the display portion 462 may have the same structure or two or more different structures.

The connection portion 204 is provided in a region of the substrate 451 which does not overlap with the substrate 452. In the connection portion 204, the wiring 465 is electrically connected to the FPC472 through the conductive layer 466 and the connection layer 242. As the conductive layer 466, a conductive film obtained by processing the same conductive film as the pixel electrode or a conductive film obtained by processing a stacked film of the same conductive film as the pixel electrode and the same conductive film as the optical adjustment layer can be used. The conductive layer 466 is exposed on the top surface of the connection portion 204. Accordingly, the connection portion 204 can be electrically connected to the FPC472 through the connection layer 242.

The light shielding layer 417 is preferably provided on the surface of the substrate 452 on the substrate 451 side. Further, various optical members may be arranged outside the substrate 452. As the optical member, a polarizing plate, a retardation plate, a light diffusion layer (diffusion film or the like), an antireflection layer, a condensing film (condensing film) or the like can be used. Further, an antistatic film which suppresses adhesion of dust, a film which is less likely to be stained and has water repellency, a hard coat film which suppresses damage in use, an impact absorbing layer, and the like may be disposed on the outer side of the substrate 452.

By forming the protective layer 410 covering the light-emitting element, entry of impurities such as water into the light-emitting element can be suppressed, whereby the reliability of the light-emitting element can be improved.

In the region 228 near the end portion of the display device 400A, it is preferable that the insulating layer 215 and the protective layer 410 be in contact with each other through the opening of the insulating layer 214. In particular, it is particularly preferable that the inorganic insulating film contained in the insulating layer 215 and the inorganic insulating film contained in the protective layer 410 be in contact with each other. Thus, the entry of impurities into the display portion 462 from the outside through the organic insulating film can be suppressed. Accordingly, the reliability of the display device 400A can be improved.

As the substrate 451 and the substrate 452, glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, or the like can be used. As a substrate on the side from which light is extracted from the light-emitting element, a material that transmits the light is used. By using a material having flexibility for the substrate 451 and the substrate 452, flexibility of the display device can be improved. As the substrate 451 or the substrate 452, a polarizing plate can be used.

As the substrate 451 and the substrate 452, the following materials can be used: polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyacrylonitrile resins, acrylic resins, polyimide resins, polymethyl methacrylate resins, polycarbonate (PC) resins, polyethersulfone (PES) resins, polyamide resins (nylon, aramid, etc.), polysiloxane resins, cycloolefin resins, polystyrene resins, polyamide-imide resins, polyurethane resins, polyvinyl chloride resins, polyvinylidene chloride resins, polypropylene resins, polytetrafluoroethylene (PTFE) resins, ABS resins, cellulose nanofibers, and the like. Further, glass having a thickness of a degree of flexibility may be used as one or both of the substrate 451 and the substrate 452.

In the case of overlapping the circularly polarizing plate on the display device, a substrate having high optical isotropy is preferably used as the substrate included in the display device. Substrates with high optical isotropy have lower birefringence (also referred to as lower birefringence).

The absolute value of the phase difference value (retardation value) of the substrate having high optical isotropy is preferably 30nm or less, more preferably 20nm or less, and further preferably 10nm or less.

Examples of the film having high optical isotropy include a cellulose triacetate (also referred to as TAC: cellulose triacetate) film, a cycloolefin polymer (COP) film, a cycloolefin copolymer (COC) film, and an acrylic film.

When a film is used as a substrate, there is a possibility that shape changes such as wrinkles in the display panel occur due to water absorption of the film. Therefore, a film having low water absorption is preferably used as the substrate. For example, a film having a water absorption of 1% or less is preferably used, a film having a water absorption of 0.1% or less is more preferably used, and a film having a water absorption of 0.01% or less is more preferably used.

As the adhesive layer, various kinds of cured adhesives such as a photo-cured adhesive such as an ultraviolet-cured adhesive, a reaction-cured adhesive, a heat-cured adhesive, and an anaerobic adhesive can be used. Examples of such binders include epoxy resins, acrylic resins, silicone resins, phenolic resins, polyimide resins, imide resins, PVC (polyvinyl chloride) resins, PVB (polyvinyl butyral) resins, and EVA (ethylene-vinyl acetate) resins. In particular, a material having low moisture permeability such as epoxy resin is preferably used. In addition, a two-liquid mixed type resin may be used. In addition, an adhesive sheet or the like may be used.

As the connection layer 242, an anisotropic conductive film (ACF: anisotropic Conductive Film), an anisotropic conductive paste (ACP: anisotropic Conductive Paste), or the like can be used.

Examples of materials that can be used for the gate electrode, source electrode, drain electrode, various wirings constituting a display device, and conductive layers such as electrodes include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, and alloys containing the metals as main components. A single layer or a stack of films comprising these materials may be used.

As the light-transmitting conductive material, a conductive oxide such as indium oxide, indium tin oxide, indium zinc oxide, or zinc oxide containing gallium, or graphene can be used. Alternatively, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium, or an alloy material containing the metal material may be used. Alternatively, a nitride (e.g., titanium nitride) of the metal material or the like may be used. Further, when a metal material or an alloy material (or their nitrides) is used, it is preferable to form it thin so as to have light transmittance. In addition, a laminated film of the above materials can be used as the conductive layer. For example, a laminate film of an alloy of silver and magnesium and indium tin oxide is preferable because conductivity can be improved. The above material can be used for a conductive layer included in a light-emitting element or a conductive layer (used as a conductive layer of a pixel electrode or a common electrode) and a conductive layer of various wirings, electrodes, or the like which form a display device.

Examples of the insulating material that can be used for each insulating layer include resins such as acrylic resin and epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

Transistor 201 and transistor 205 include: a conductive layer 221 serving as a gate electrode; an insulating layer 211 serving as a gate insulating layer; a semiconductor layer including a channel formation region 231i and a pair of low-resistance regions 231 n; a conductive layer 222a connected to one of the pair of low-resistance regions 231 n; a conductive layer 222b connected to the other of the pair of low-resistance regions 231 n; an insulating layer 225 serving as a gate insulating layer; a conductive layer 223 serving as a gate electrode; and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel formation region 231 i. The insulating layer 225 is located between the conductive layer 223 and the channel formation region 231 i.

The conductive layer 222a and the conductive layer 222b are connected to the low-resistance region 231n through openings provided in the insulating layer 215 and the insulating layer 225. One of the conductive layer 222a and the conductive layer 222b functions as a source, and the other functions as a drain.

Fig. 11B shows an example in which the insulating layer 225 covers the top surface and the side surfaces of the semiconductor layer. The conductive layer 222a and the conductive layer 222b are connected to the low-resistance region 231n through openings provided in the insulating layer 225 and the insulating layer 215.

On the other hand, in the transistor 209 illustrated in fig. 11C, the insulating layer 225 overlaps with the channel formation region 231i of the semiconductor layer 231 and does not overlap with the low-resistance region 231 n. For example, the structure shown in fig. 11C can be formed by processing the insulating layer 225 using the conductive layer 223 as a mask. In fig. 11C, the insulating layer 215 covers the insulating layer 225 and the conductive layer 223, and the conductive layer 222a and the conductive layer 222b are connected to the low-resistance region 231n through openings of the insulating layer 215, respectively. Furthermore, an insulating layer 218 covering the transistor may be provided.

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

By using a transistor using silicon such as 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 a semiconductor 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 the OS transistor is much higher than that of 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. In addition, a structure in which LTPS transistors and OS transistors are combined is sometimes referred to as LTPO. Further, as a more preferable example, an OS transistor is preferably used for a transistor or the like used as a switch for controlling conduction/non-conduction between wirings, and an LTPS transistor is preferably used for a transistor or the like 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 element, 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 element. LTPS transistors are preferably used as the driving transistors. Therefore, the current flowing through the light emitting element in the pixel circuit can be increased.

On the other hand, the other of the transistors provided in the pixel circuit is used as a switch for controlling selection/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. Therefore, the gradation of the pixel can be maintained even if the frame rate is made significantly small (for example, 1fps or less), whereby by stopping the driver when displaying a still image, the power consumption can be reduced.

Thus, the display device with high aperture ratio, high definition, high display quality and low power consumption can be realized according to one embodiment of the present invention.

At least a part of the structural example shown in the present embodiment and the drawings corresponding to the structural example may be appropriately combined with other structural examples, drawings, and the like.

Embodiment 3

In this embodiment, a configuration example of a display device different from the above will be described.

The display device of the present embodiment may be a high-definition display device. Therefore, the display device according to the present embodiment can be used as a display unit of a wearable device such as a VR device such as a wristwatch or a bracelet-type information terminal device (wearable device) and a glasses-type AR device.

[ display Module ]

Fig. 12A is a perspective view of the display module 280. The display module 280 includes a display device 400C and an FPC290. Note that the display device included in the display module 280 is not limited to the display device 400C, and may be a display device 400D, a display device 400E, or a display device 400F which will be described later.

The display module 280 includes a substrate 291 and a substrate 292. The display module 280 includes a display portion 281. The display portion 281 is an image display area in the display module 280, and can see light from each pixel provided in a pixel portion 284 described below.

Fig. 12B is a schematic perspective view of a structure on the side of the substrate 291. A circuit portion 282, a pixel circuit portion 283 on the circuit portion 282, and a pixel portion 284 on the pixel circuit portion 283 are stacked over the substrate 291. Further, a terminal portion 285 for connection to the FPC290 is provided over a portion of the substrate 291 which does not overlap with the pixel portion 284. The terminal portion 285 is electrically connected to the circuit portion 282 through a wiring portion 286 composed of a plurality of wirings.

The pixel portion 284 includes a plurality of pixels 284a arranged periodically. An enlarged view of one pixel 284a is shown on the right side of fig. 12B. The pixel 284a includes light emitting elements 430a, 430b, 430c that emit light of different colors from each other. The plurality of light emitting elements may be arranged in a stripe arrangement as shown in fig. 12B. Since the light emitting elements according to one embodiment of the present invention can be arranged in the pixel circuit with high density by using the stripe arrangement, a high-definition display device can be provided. In addition, various arrangement methods such as a triangular arrangement and a Pentile arrangement may be employed.

The pixel circuit portion 283 includes a plurality of pixel circuits 283a arranged periodically.

One pixel circuit 283a controls light emission of three light emitting elements included in one pixel 284a. One pixel circuit 283a may be constituted by three circuits that control light emission of one light emitting element. For example, the pixel circuit 283a may have a structure including at least one selection transistor, one transistor for current control (driving transistor), and a capacitor for one light-emitting element. At this time, a gate signal is input to the gate of the selection transistor, and a source signal is input to one of the source and the drain. Thus, an active matrix display device is realized.

The circuit portion 282 includes a circuit for driving each pixel circuit 283a of the pixel circuit portion 283. For example, one or both of the gate line driver circuit and the source line driver circuit are preferably included. Further, at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like may be provided.

The FPC290 serves as a wiring for supplying video signals, power supply potentials, and the like to the circuit portion 282 from the outside. Further, an IC may be mounted on the FPC 290.

The display module 280 may have a structure in which one or both of the pixel circuit portion 283 and the circuit portion 282 are laminated under the pixel portion 284, and thus the display portion 281 can have a very high aperture ratio (effective display area ratio). For example, the aperture ratio of the display portion 281 may be 40% or more and less than 100%, preferably 50% or more and 95% or less, and more preferably 60% or more and 95% or less. Further, the pixels 284a can be arranged at an extremely high density, whereby the display portion 281 can have extremely high definition. For example, the display portion 281 preferably configures the pixel 284a with a definition of 20000ppi or less or 30000ppi or less and 2000ppi or more, more preferably 3000ppi or more, still more preferably 5000ppi or more, still more preferably 6000ppi or more.

Such a high-definition display module 280 is suitable for VR devices such as head-mounted displays and glasses-type AR devices. For example, since the display module 280 has the display portion 281 of extremely high definition, in a structure in which the display portion of the display module 280 is viewed through a lens, the user cannot see the pixels even if the display portion is enlarged by the lens, whereby display with high immersion can be achieved. In addition, the display module 280 may be applied to an electronic device having a relatively small display part. For example, the display unit is suitable for a wearable electronic device such as a wristwatch type device.

Display device 400C

The display device 400C shown in fig. 13 includes a substrate 301, light-emitting elements 430a, 430b, and 430C, a capacitor 240, and a transistor 310.

The transistor 310 is a transistor having a channel formation region in the substrate 301. As the substrate 301, a semiconductor substrate such as a single crystal silicon substrate can be used, for example. Transistor 310 includes a portion of substrate 301, conductive layer 311, low resistance region 312, insulating layer 313, and insulating layer 314. The conductive layer 311 is used as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311, and is used as a gate insulating layer. The low resistance region 312 is a region doped with impurities in the substrate 301, and is used as one of a source and a drain. The insulating layer 314 covers the side surface of the conductive layer 311 and is used as an insulating layer.

Further, between the adjacent two transistors 310, an element separation layer 315 is provided so as to be embedded in the substrate 301.

Further, an insulating layer 261 is provided so as to cover the transistor 310, and the capacitor 240 is provided over the insulating layer 261.

The capacitor 240 includes a conductive layer 241, a conductive layer 245, and an insulating layer 243 therebetween. The conductive layer 241 serves as one electrode in the capacitor 240, the conductive layer 245 serves as the other electrode in the capacitor 240, and the insulating layer 243 serves as a dielectric of the capacitor 240.

The conductive layer 241 is disposed on the insulating layer 261 and embedded in the insulating layer 254. The conductive layer 241 is electrically connected to one of a source and a drain of the transistor 310 through a plug 271 embedded in the insulating layer 261. The insulating layer 243 is provided so as to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping with the conductive layer 241 with the insulating layer 243 interposed therebetween.

An insulating layer 255 is provided so as to cover the capacitor 240, and light emitting elements 430a, 430b, 430c, and the like are provided over the insulating layer 255. The light-emitting elements 430a, 430b, and 430c are provided with a protective layer 416, and the substrate 420 is bonded to the top surface of the protective layer 416 via a resin layer 419. The substrate 420 corresponds to the substrate 292 in fig. 12A.

The pixel electrode of the light emitting element is electrically connected to one of the source and the drain of the transistor 310 through the plug 256 embedded in the insulating layer 255, the conductive layer 241 embedded in the insulating layer 254, and the plug 271 embedded in the insulating layer 261.

Display device 400D

The display device 400D shown in fig. 14 is mainly different from the display device 400C in the structure of a transistor. Note that the same portions as those of the display device 400C may be omitted.

The transistor 320 is a transistor using a metal oxide (also referred to as an oxide semiconductor) in a semiconductor layer which forms a channel.

The transistor 320 includes a semiconductor layer 321, an insulating layer 323, a conductive layer 324, a pair of conductive layers 325, an insulating layer 326, and a conductive layer 327.

The substrate 331 corresponds to the substrate 291 in fig. 12A and 12B. As the substrate 331, an insulating substrate or a semiconductor substrate can be used.

An insulating layer 332 is provided over the substrate 331. The insulating layer 332 functions as a barrier layer which prevents diffusion of impurities such as water or hydrogen from the substrate 331 to the transistor 320 and prevents oxygen from being released from the semiconductor layer 321 to the insulating layer 332 side. As the insulating layer 332, for example, a film which is less likely to be diffused by hydrogen or oxygen than a silicon oxide film, such as an aluminum oxide film, a hafnium oxide film, a silicon nitride film, or the like can be used.

A conductive layer 327 is provided over the insulating layer 332, and an insulating layer 326 is provided so as to cover the conductive layer 327. The conductive layer 327 serves as a first gate electrode of the transistor 320, and a portion of the insulating layer 326 serves as a first gate insulating layer. At least a portion of the insulating layer 326 which contacts the semiconductor layer 321 is preferably an oxide insulating film such as a silicon oxide film. The top surface of insulating layer 326 is preferably planarized.

The semiconductor layer 321 is disposed on the insulating layer 326. The semiconductor layer 321 preferably contains a metal oxide (also referred to as an oxide semiconductor) film having semiconductor characteristics. The material that can be used for the semiconductor layer 321 will be described in detail later.

A pair of conductive layers 325 are in contact with the semiconductor layer 321 and serve as source and drain electrodes.

Further, an insulating layer 328 is provided so as to cover the top surface and the side surfaces of the pair of conductive layers 325, the side surfaces of the semiconductor layer 321, and the like, and an insulating layer 264 is provided over the insulating layer 328. The insulating layer 328 serves as a barrier layer that prevents diffusion of impurities such as water and hydrogen from the insulating layer 264 or the like to the semiconductor layer 321 and separation of oxygen from the semiconductor layer 321. As the insulating layer 328, an insulating film similar to the insulating layer 332 described above can be used.

Openings reaching the semiconductor layer 321 are provided in the insulating layer 328 and the insulating layer 264. The opening is internally embedded with an insulating layer 323 and a conductive layer 324 which are in contact with the side surfaces of the insulating layer 264, the insulating layer 328, and the conductive layer 325, and the top surface of the semiconductor layer 321. The conductive layer 324 is used as a second gate electrode, and the insulating layer 323 is used as a second gate insulating layer.

The top surface of the conductive layer 324, the top surface of the insulating layer 323, and the top surface of the insulating layer 264 are planarized to have substantially the same height, and an insulating layer 329 and an insulating layer 265 are provided so as to cover them.

The insulating layers 264 and 265 are used as interlayer insulating layers. The insulating layer 329 serves as a barrier layer which prevents diffusion of impurities such as water or hydrogen from the insulating layer 265 or the like to the transistor 320. The insulating layer 329 can be formed using the same insulating film as the insulating layer 328 and the insulating layer 332.

A plug 274 electrically connected to one of the pair of conductive layers 325 is embedded in the insulating layer 265, the insulating layer 329, and the insulating layer 264. Here, the plug 274 preferably has a conductive layer 274a covering the side surfaces of the openings of the insulating layer 265, the insulating layer 329, the insulating layer 264, and the insulating layer 328 and a part of the top surface of the conductive layer 325, and a conductive layer 274b in contact with the top surface of the conductive layer 274 a. In this case, a conductive material which does not easily diffuse hydrogen and oxygen is preferably used for the conductive layer 274 a.

The structure from the insulating layer 254 to the substrate 420 in the display device 400D is the same as that of the display device 400C.

Display device 400E

The display device 400E shown in fig. 15 has a stacked structure of a transistor 310A and a transistor 310B whose channels are formed in a semiconductor substrate, respectively.

The display device 400E has a structure in which a substrate 301B provided with the transistor 310B, the capacitor 240, and each light-emitting device is bonded to a substrate 301A provided with the transistor 310A.

A plug 343 penetrating the substrate 301B is provided in the substrate 301B. In addition, the plug 343 is electrically connected to the conductive layer 342 provided on the back surface (surface on the opposite side to the substrate 420) of the substrate 301B. On the other hand, the substrate 301A is provided with a conductive layer 341 over the insulating layer 261.

By bonding the conductive layer 341 and the conductive layer 342, the substrate 301A is electrically connected to the substrate 301B.

The same conductive material is preferably used for the conductive layer 341 and the conductive layer 342. For example, a metal film containing an element selected from Al, cr, cu, ta, ti, mo and W, a metal nitride film (titanium nitride film, molybdenum nitride film, tungsten nitride film) containing the above element as a component, or the like can be used. In particular, copper is preferably used for the conductive layer 341 and the conductive layer 342. Thus, a cu—cu (copper-copper) direct bonding technique (a technique of forming electrical conduction by connecting Cu (copper) pads) can be used. In addition, the conductive layer 341 and the conductive layer 342 may be bonded by a bump.

Display device 400F

In the display device 400F shown in fig. 16, a transistor 310 in which a channel is formed over a substrate 301 and a transistor 320 in which a semiconductor layer forming a channel contains a metal oxide are stacked. Note that the description of the same portions as those of the display devices 400C and 400D may be omitted.

An insulating layer 261 is provided so as to cover the transistor 310, and a conductive layer 251 is provided over the insulating layer 261. Further, an insulating layer 262 is provided so as to cover the conductive layer 251, and the conductive layer 252 is provided over the insulating layer 262. Both the conductive layer 251 and the conductive layer 252 are used as wirings. Further, an insulating layer 263 and an insulating layer 332 are provided so as to cover the conductive layer 252, and the transistor 320 is provided over the insulating layer 332. Further, an insulating layer 265 is provided so as to cover the transistor 320, and the capacitor 240 is provided over the insulating layer 265. Capacitor 240 is electrically connected to transistor 320 through plug 274.

The transistor 320 can be used as a transistor constituting a pixel circuit. Further, the transistor 310 may be used as a transistor constituting a pixel circuit or a transistor constituting a driving circuit (a gate line driving circuit, a source line driving circuit) for driving the pixel circuit. The transistors 310 and 320 can be used as transistors constituting various circuits such as an arithmetic circuit and a memory circuit.

With this structure, not only the pixel circuit but also the driving circuit and the like can be formed immediately below the light emitting element, and therefore the display device can be miniaturized as compared with the case where the driving circuit is provided around the display region.

Embodiment 4

In this embodiment mode, a light-emitting element (also referred to as a light-emitting device) which can be used in a display device according to one embodiment of the present invention will be described.

< structural example of light-emitting device >

As shown in fig. 17A, the light-emitting device includes an EL layer 786 between a pair of electrodes (a lower electrode 772, an upper electrode 788). The EL layer 786 may be formed of a plurality of layers such as the layer 4420, the light-emitting layer 4411, and the layer 4430. The layer 4420 may include, for example, a layer containing a substance having high electron injection property (an electron injection layer), a layer containing a substance having high electron transport property (an electron transport layer), or the like. The light-emitting layer 4411 includes, for example, a light-emitting compound. The layer 4430 may include, for example, a layer containing a substance having high hole injection property (a hole injection layer) and a layer containing a substance having high hole transport property (a hole transport layer).

The structure including the layer 4420, the light-emitting layer 4411, and the layer 4430 provided between a pair of electrodes can be used as a single light-emitting unit, and the structure of fig. 17A is referred to as a single structure in this specification.

Fig. 17B shows a modified example of the EL layer 786 included in the light-emitting device shown in fig. 17A. Specifically, the light-emitting device shown in FIG. 17B includes a layer 4430-1 over a lower electrode 772, a layer 4430-2 over a layer 4430-1, a light-emitting layer 4411 over a layer 4430-2, a layer 4420-1 over a light-emitting layer 4411, a layer 4420-2 over a layer 4420-1, and an upper electrode 788 over a layer 4420-2. For example, when the lower electrode 772 is used as an anode and the upper electrode 788 is used as a cathode, the layer 4430-1 is used as a hole injection layer, the layer 4430-2 is used as a hole transport layer, the layer 4420-1 is used as an electron transport layer, and the layer 4420-2 is used as an electron injection layer. Alternatively, when the lower electrode 772 is used as a cathode and the upper electrode 788 is used as an anode, the layer 4430-1 is used as an electron injection layer, the layer 4430-2 is used as an electron transport layer, the layer 4420-1 is used as a hole transport layer, and the layer 4420-2 is used as a hole injection layer. By adopting the above layer structure, carriers can be efficiently injected into the light-emitting layer 4411, whereby recombination efficiency of carriers in the light-emitting layer 4411 can be improved.

As shown in fig. 17C and 17D, a structure in which a plurality of light-emitting layers (light-emitting layers 4411, 4412, and 4413) are provided between the layers 4420 and 4430 is also a modification example of a single structure.

As shown in fig. 17E and 17F, a structure in which a plurality of light emitting units (EL layers 786a and 786 b) are connected in series with an intermediate layer (charge generation layer) 4440 interposed therebetween is referred to as a series structure in this specification. In the present specification and the like, the structure shown in fig. 17E and 17F is referred to as a series structure, but is not limited thereto, and for example, the series structure may be referred to as a stacked structure. By adopting the series structure, a light-emitting device capable of emitting light with high luminance can be realized.

In fig. 17C, the light-emitting layer 4411, the light-emitting layer 4412, and the light-emitting layer 4413 which emit light of the same color may be formed.

In addition, light-emitting materials different from each other may be used for the light-emitting layer 4411, the light-emitting layer 4412, and the light-emitting layer 4413. When the light emitted from each of the light-emitting layers 4411, 4412, and 4413 is in a complementary color relationship, white light emission can be obtained. Fig. 17D shows an example in which a coloring layer 785 used as a color filter is provided. The white light is transmitted through the color filter, whereby light of a desired color can be obtained.

In fig. 17E, the same light-emitting material may be used for the light-emitting layer 4411 and the light-emitting layer 4412. Alternatively, light-emitting materials which emit light of different colors may be used for the light-emitting layers 4411 and 4412. When the light emitted from the light-emitting layer 4411 and the light emitted from the light-emitting layer 4412 are in a complementary color relationship, white light emission can be obtained. Fig. 17F shows an example in which a coloring layer 785 is also provided.

Note that in fig. 17C, 17D, 17E, and 17F, as shown in fig. 17B, the layers 4420 and 4430 may have a stacked structure including two or more layers.

A structure in which light emitting layers (here, blue (B), green (G), and red (R)) are formed for each light emitting device is referred to as a SBS (Side By Side) structure.

The light emitting color of the light emitting device can be red, green, blue, cyan, magenta, yellow, white, or the like depending on the material constituting the EL layer 786. In addition, when the light emitting device has a microcavity structure, color purity can be further improved.

The white light emitting device preferably has a structure in which the light emitting layer contains two or more kinds of light emitting substances. In order to obtain white light emission, two or more kinds of light-emitting substances each having a complementary color relationship may be selected. For example, by placing the light-emitting color of the first light-emitting layer and the light-emitting color of the second light-emitting layer in a complementary relationship, a light-emitting device that emits light in white color as a whole can be obtained. In addition, the same applies to a light-emitting device including three or more light-emitting layers.

The light-emitting layer preferably contains two or more kinds of light-emitting substances each of which emits light such as R (red), G (green), B (blue), Y (yellow), O (orange), and the like. Alternatively, two or more luminescent materials each of which emits light and contains two or more spectral components in R, G, B are preferably contained.

Here, a specific structural example of the light emitting device is explained.

The light emitting device includes at least a light emitting layer. The light-emitting device may further include, as a layer other than the light-emitting layer, a layer containing a substance having high hole injection property, a substance having high hole transport property, a hole blocking material, a substance having high electron transport property, an electron blocking material, a substance having high electron injection property, a bipolar substance (a substance having high electron transport property and hole transport property), or the like.

The light-emitting device may use a low-molecular compound or a high-molecular compound, and may further contain an inorganic compound. The layers constituting the light-emitting device can be formed by a method such as a vapor deposition method (including a vacuum vapor deposition method), a transfer method, a printing method, an inkjet method, or a coating method.

For example, the light emitting device may include one or more of a hole injection layer, a hole transport layer, a hole blocking layer, an electron transport layer, and an electron injection layer in addition to the light emitting layer.

The hole injection layer is a layer that injects holes from the anode to the hole transport layer, and includes a material having high hole injection property. As the material having high hole injection property, an aromatic amine compound, a composite material containing a hole transporting material and an acceptor material (electron acceptor material), or the like can be used.

The hole transport layer is a layer that transports holes injected from the anode by the hole injection layer into the light emitting layer. The hole transport layer is a layer containing a hole transporting material. As the hole transporting material, a material having a hole mobility of 10 is preferably used ^-6 cm ² Materials above/Vs. In addition, as long as it is a substance having a higher hole-transporting property than electron-transporting propertyTo use materials other than those described above. As the hole transporting material, a material having high hole transporting property such as a pi-electron rich heteroaromatic compound (for example, a carbazole derivative, a thiophene derivative, a furan derivative, or the like) or an aromatic amine (a compound including an aromatic amine skeleton) is preferably used.

The electron transport layer is a layer that transports electrons injected from the cathode by the electron injection layer into the light emitting layer. The electron transport layer is a layer containing an electron transport material. As the electron transporting material, an electron mobility of 1X 10 is preferably used ^-6 cm ² Materials above/Vs. Further, any substance other than the above may be used as long as it has an electron-transporting property higher than a hole-transporting property. Examples of the electron-transporting material include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, metal complexes having a thiazole skeleton, and the like, and examples of the electron-transporting material include materials having high electron-transporting properties such as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and nitrogen-containing heteroaromatic compounds.

The electron injection layer is a layer containing a material having high electron injection property, which injects electrons from the cathode to the electron transport layer. As the material having high electron injection properties, alkali metal, alkaline earth metal, or a compound containing the above can be used. As the material having high electron injection properties, a composite material containing an electron-transporting material and a donor material (electron-donor material) may be used.

Examples of the electron injection layer include lithium, cesium, lithium fluoride (LiF), cesium fluoride (CsF), and calcium fluoride (CaF) ₂ ) 8- (hydroxyquinoxaline) lithium (abbreviation: liq), lithium 2- (2-pyridyl) phenoxide (abbreviation: liPP), lithium 2- (2-pyridyl) -3-hydroxypyridine (abbreviation: liPPy), lithium 4-phenyl-2- (2-pyridyl) phenol (abbreviation: liPPP), lithium oxide (LiO _x ) Alkali metal such as cesium carbonate,Alkaline earth metals or their compounds.

As the electron injection layer, a material having electron transport property may be used. For example, a compound having an electron-deficient heteroaromatic ring with an unshared electron pair can be used for a material having electron-transporting properties. Specifically, a compound containing at least one of a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, pyridazine ring), and a triazine ring can be used.

The lowest unoccupied molecular orbital (LUMO: lowest Unoccupied Molecular Orbital) of an organic compound having an unshared electron pair is preferably-3.6 eV or more and-2.3 eV or less. In general, CV (cyclic voltammetry), photoelectron spectroscopy (photoelectron spectroscopy), absorption spectroscopy (optical absorption spectroscopy) and reverse-light electron spectroscopy estimate the highest occupied molecular orbital (HOMO: highest Occupied Molecular Orbital) energy level and LUMO energy level of an organic compound.

For example, 4, 7-diphenyl-1, 10-phenanthroline (abbreviated as BPhen), 2, 9-bis (naphthalen-2-yl) -4, 7-diphenyl-1, 10-phenanthroline (abbreviated as NBPhen), and a diquinoxalino [2,3-a:2',3' -c ] phenazine (abbreviated as HATNA), 2,4, 6-tris [3' - (pyridin-3-yl) biphenyl-3-yl ] -1,3, 5-triazine (abbreviated as TmPPyTz) and the like are used for organic compounds having an unshared electron pair. In addition, NBPhen has a high glass transition temperature (Tg) and good heat resistance compared to BPhen.

The light-emitting layer is a layer containing a light-emitting substance. The light emitting layer may comprise one or more light emitting substances. As the light-emitting substance, a substance exhibiting a light-emitting color such as blue, violet, bluish violet, green, yellowish green, yellow, orange, or red is suitably used. Further, as the light-emitting substance, a substance that emits near infrared light may be used.

Examples of the luminescent material include a fluorescent material, a phosphorescent material, a TADF material, and a quantum dot material.

Examples of the fluorescent material include pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, naphthalene derivatives, and the like.

Examples of the phosphorescent material include an organometallic complex (particularly iridium complex) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton, and a pyridine skeleton, an organometallic complex (particularly iridium complex) having a phenylpyridine derivative having an electron-withdrawing group as a ligand, a platinum complex, and a rare earth metal complex.

The light-emitting layer may contain one or more organic compounds (host material, auxiliary material, etc.) in addition to the light-emitting substance (guest material). As the one or more organic compounds, one or both of a hole transporting material and an electron transporting material may be used. Furthermore, as one or more organic compounds, bipolar materials or TADF materials may also be used.

For example, the light-emitting layer preferably contains a combination of a phosphorescent material, a hole-transporting material that easily forms an exciplex, and an electron-transporting material. By adopting such a structure, light emission of ExTET (Excilex-Triplet Energy Transfer: exciplex-triplet energy transfer) utilizing energy transfer from an Exciplex to a light-emitting substance (phosphorescent material) can be obtained efficiently. By selecting the mixed material in such a manner that an exciplex emitting light overlapping with the wavelength of the absorption band on the lowest energy side of the light-emitting material is formed, energy transfer can be made smooth, and light emission can be obtained efficiently. Due to this structure, high efficiency, low voltage driving, and long life of the light emitting device can be simultaneously achieved.

This embodiment mode can be combined with other embodiment modes 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 the above embodiment mode is described.

The metal oxide preferably contains at least indium or zinc. Particularly preferred are indium and zinc. In addition, aluminum, gallium, yttrium, tin, or the like is preferably contained. Further, one or more selected from boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, cobalt, and the like may be contained.

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

< 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.

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 IGZO film having a crystalline 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. Further, a spot-like pattern was observed in the diffraction pattern of the IGZO film formed at room temperature, and no halation was observed. It is therefore presumed that an IGZO film formed at room temperature is in an intermediate state where it is neither crystalline nor amorphous, and it cannot be concluded that the IGZO 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. The non-single crystal oxide semiconductor includes a polycrystalline oxide semiconductor, an a-like OS (amorphorus-like oxide semiconductor), an amorphous oxide semiconductor, and the like.

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, in the In-M-Zn oxide (element M is one or more selected from aluminum, gallium, yttrium, tin, titanium, and the like), CAAC-OS tends to have 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 element M, zinc (Zn) and oxygen (hereinafter, (M, zn layer) are stacked. Furthermore, indium and the element M may be substituted for each other. Therefore, the (M, zn) layer sometimes contains indium. In addition, the In layer sometimes contains an element M. Note that sometimes the In layer contains Zn. 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 indicating 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 indicating the c-axis orientation may vary depending on the kind, composition, and the like 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, the distortion may have a lattice arrangement such as pentagonal or heptagonal. 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 because CAAC-OS can accommodate distortion due to low density of arrangement of oxygen atoms in the a-b face direction, variation in bonding distance between atoms due to substitution of metal atoms, and the like.

In addition, it was confirmed that the crystal structure of the clear grain boundary was called poly crystal (polycrystalline). Since the grain boundary serves as a recombination center and carriers are trapped, there is a possibility that on-state current of the transistor is lowered, field effect mobility is lowered, or the like. 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, generation of defects, or the like, CAAC-OS is said to be an oxide semiconductor with few impurities and defects (oxygen vacancies, or the like). 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 and amorphous oxide semiconductor in some analysis 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. In addition, 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, indium zinc oxide, or the like. The second region is a region mainly composed of gallium oxide, gallium zinc oxide, or the like. 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 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. The lower the flow rate ratio of the oxygen gas in the total flow rate of the deposition gas at the time of deposition, 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 preferably set to 0% or more and less than 30%, more 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 (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 for the transistor, 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 such as 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 of an amorphous oxide semiconductor, a polycrystalline oxide semiconductor, a-likeOS, 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 is 1X 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 this specification and the like, a state in which the impurity concentration is low and the defect state density is low is referred to as a 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, silicon, and the like.

< 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 and carbon in the oxide semiconductor and 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. Thus, an oxide semiconductor containing an alkali metal or an alkaline earth metal is used Transistors tend to have 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, the electrical characteristics of the transistor may be 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, in the oxide semiconductor, the hydrogen concentration 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.

Embodiment 6

In this embodiment, an electronic device according to an embodiment of the present invention will be described with reference to fig. 18A to 21F.

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

In addition, the display device according to one embodiment of the present invention can be manufactured at low cost, and thus the manufacturing cost of the electronic apparatus can be reduced.

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 or the like, a digital signage, a large-sized game machine such as a pachinko machine, and the like, 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 information terminal devices (wearable devices) such as wristwatches and bracelets, VR devices such as head mounted displays such as wearable devices that can be worn on the head, and glasses-type AR devices. Further, as the wearable device, an SR device and an MR device can be mentioned.

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), 4K2K (3840×2160 in pixel number), 8K4K (7680×4320 in pixel number), and the like. Particularly preferably with a resolution of 4K2K, 8K4K or higher. In the display device according to one embodiment of the present invention, the pixel density (sharpness) is preferably 300ppi or more, 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, still more preferably 7000ppi or more. By using the display device having high resolution or high definition, the sense of realism, sense of depth, and the like can be further improved in an electronic device for personal use such as a portable device or a home device.

The electronic device according to the present embodiment can be assembled along a curved surface of an inner wall or an outer wall of a house or a high building, an interior or an exterior of an automobile.

The electronic device of the present embodiment may include an antenna. By receiving the signal from the antenna, an image, information, and the like can be displayed on the display unit. In addition, when the electronic device includes an antenna and a secondary battery, noncontact power transmission can be performed by the antenna.

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).

The electronic device of the present embodiment may have various functions. For example, it may have the following functions: a function of displaying various information (still image, moving image, character image, etc.) on the display section; a function of the touch panel; a function of displaying a calendar, date, time, or the like; executing functions of various software (programs); a function of performing wireless communication; a function of reading out a program or data stored in the storage medium; etc.

The electronic device 6500 shown in fig. 18A is a portable information terminal device that can be used as a smartphone.

The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, a light source 6508, and the like. The display portion 6502 has a touch panel function.

The display portion 6502 can use a display device according to one embodiment of the present invention.

Fig. 18B is a schematic cross-sectional view of an end portion on the microphone 6506 side including the housing 6501.

A light-transmissive protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, an optical member 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, and the like are provided in a space surrounded by the housing 6501 and the protective member 6510.

The display panel 6511, the optical member 6512, and the touch sensor panel 6513 are fixed to the protective member 6510 using an adhesive layer (not shown).

In an area outside the display portion 6502, a part of the display panel 6511 is overlapped, and the overlapped part is connected with an FPC6515. The FPC6515 is mounted with an IC6516. The FPC6515 is connected to terminals provided on the printed circuit board 6517.

The display panel 6511 can use a flexible display (a display device having flexibility) according to one embodiment of the present invention. Thus, an extremely lightweight electronic device can be realized. Further, since the display panel 6511 is extremely thin, the large-capacity battery 6518 can be mounted while suppressing the thickness of the electronic apparatus. Further, by folding a part of the display panel 6511 to provide a connection portion with the FPC6515 on the back surface of the pixel portion, a narrow-frame electronic device can be realized.

Fig. 19A 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 television device 7100 shown in fig. 19A can be operated by using an operation switch included in the housing 7101 and a remote control operation unit 7111 provided separately. The display 7000 may include a touch sensor, or the television device 7100 may be operated by touching the display 7000 with a finger or the like. The remote controller 7111 may include a display unit for displaying information output from the remote controller 7111. By using the operation keys or touch panel included 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, a modem, and the like. 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, and information communication is performed in one direction (from a sender to a receiver) or in two directions (between a sender and a receiver, between receivers, or the like).

Fig. 19B shows an example of a notebook personal computer. The notebook personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. The display unit 7000 is incorporated in the housing 7211.

Fig. 19C and 19D show one example of a digital signage.

The digital signage 7300 shown in fig. 19C includes a housing 7301, a display portion 7000, a speaker 7303, and the like. Further, an LED lamp, an operation key (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like may be included.

Fig. 19D 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. 19C and 19D, a display device including a transistor according to one embodiment of the present invention can be applied to the display portion 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, in the application for providing information such as route information and traffic information, usability can be improved by intuitive operation.

As shown in fig. 19C and 19D, the digital signage 7300 or 7400 can preferably be linked to an information terminal device 7311 or 7411 such as a smart phone carried by a user by wireless communication. For example, the advertisement information displayed on the display portion 7000 may be displayed on the screen of the information terminal device 7311 or the information terminal device 7411. Further, by operating the information terminal device 7311 or the information terminal device 7411, the display of the display portion 7000 can be switched.

Further, a game may be executed on the digital signage 7300 or the digital signage 7400 with the screen of the information terminal apparatus 7311 or the information terminal apparatus 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.

Fig. 20A is an external view of a camera 8000 mounted with a viewfinder 8100.

The camera 8000 includes a housing 8001, a display portion 8002, operation buttons 8003, shutter buttons 8004, and the like. Further, a detachable lens 8006 is attached to the camera 8000. In the camera 8000, the lens 8006 and the housing may be formed integrally.

The camera 8000 can perform imaging by pressing a shutter button 8004 or touching a display portion 8002 serving as a touch panel.

The housing 8001 includes an interposer having electrodes, and may be connected to a flash device or the like in addition to the viewfinder 8100.

The viewfinder 8100 includes a housing 8101, a display portion 8102, buttons 8103, and the like.

The housing 8101 is attached to the camera 8000 by an embedder that is embedded in the camera 8000. The viewfinder 8100 can display an image or the like received from the camera 8000 on the display portion 8102.

The button 8103 is used as a power button or the like.

The display device according to one embodiment of the present invention can be used for the display portion 8002 of the camera 8000 and the display portion 8102 of the viewfinder 8100. A viewfinder may be incorporated in the camera 8000.

Fig. 20B is an external view of the head mounted display 8200.

The head mount display 8200 includes a mounting portion 8201, a lens 8202, a main body 8203, a display portion 8204, a cable 8205, and the like. Further, a battery 8206 is incorporated in the mounting portion 8201.

Power is supplied from the battery 8206 to the main body 8203 via the cable 8205. The main body 8203 includes a wireless receiver or the like, and can display received video information or the like on the display unit 8204. Further, the main body 8203 has a camera, and thus information of the movement of the eyeball or eyelid of the user can be utilized as an input method.

Further, a plurality of electrodes may be provided to the mounting portion 8201 at positions contacted by the user to detect a current flowing through the electrodes in accordance with the movement of the eyeballs of the user, thereby realizing the function of recognizing the line of sight of the user. Further, the electrode may have a function of monitoring the pulse of the user based on the current flowing through the electrode. The mounting portion 8201 may have various sensors such as a temperature sensor, a pressure sensor, and an acceleration sensor, or may have a function of displaying biological information of the user on the display portion 8204, a function of changing an image displayed on the display portion 8204 in synchronization with the operation of the head of the user, or the like.

The display device according to one embodiment of the present invention can be used for the display portion 8204.

Fig. 20C to 20E are external views of the head mounted display 8300. The head mount display 8300 includes a frame body 8301, a display portion 8302, a band-shaped fixing tool 8304, and a pair of lenses 8305.

The user can see the display on the display portion 8302 through the lens 8305. Preferably, the display portion 8302 is curved. Because the user can feel a high sense of realism. Further, images displayed on different areas of the display section 8302 are seen through the lenses 8305, respectively, whereby three-dimensional display or the like using parallax can be performed. In addition, one embodiment of the present invention is not limited to the configuration in which one display portion 8302 is provided, and two display portions 8302 may be provided so that one display portion is arranged for each pair of eyes of a user.

The display device according to one embodiment of the present invention can be used for the display portion 8302. The display device according to one embodiment of the present invention can also achieve extremely high definition. For example, as shown in fig. 20E, even if the display is viewed in enlargement using the lens 8305, the pixel is not easily seen by the user. That is, the display unit 8302 can allow the user to see an image with a higher sense of reality.

Fig. 20F is an external view of the goggle type head mount display 8400. The head mount display 8400 includes a pair of housings 8401, a mounting portion 8402, and a buffer member 8403. A display portion 8404 and a lens 8405 are provided in each of the pair of housings 8401. By displaying different images on the pair of display portions 8404, three-dimensional display using parallax can be performed.

The user can see the display on the display portion 8404 through the lens 8405. The lens 8405 has a focus adjustment mechanism that can adjust the position of the lens 8405 according to the user's vision. The display portion 8404 is preferably square or rectangular with a long lateral direction. Thus, the sense of realism can be improved.

The mounting portion 8402 preferably has plasticity and elasticity so as to be adjustable according to the size of the face of the user without falling down. In addition, a part of the mounting portion 8402 preferably has a vibration mechanism that is used as a bone conduction headset. Thus, the user can enjoy video and audio without any acoustic devices such as headphones and speakers. Further, the audio data may be output to the housing 8401 by wireless communication.

The mounting portion 8402 and the cushioning member 8403 are portions that contact the face (forehead, cheek, etc.) of the user. By closely contacting the buffer member 8403 with the face of the user, light leakage can be prevented, and thus the feeling of immersion can be further improved. The cushioning members 8403 preferably use a soft material to adhere to the face of the user when the head mounted display 8400 is attached to the user. For example, rubber, silicone rubber, polyurethane, sponge, or the like may be used. In addition, when a cloth, leather (natural leather, synthetic leather), or the like is used as the buffer member 8403 to cover the surface of the sponge or the like, a gap is not easily generated between the face of the user and the buffer member 8403, and thus light leakage can be appropriately prevented. In addition, when such a material is used, it is preferable not only to make the user feel skin friendly, but also to prevent the user from feeling cold when it is put on in a colder season or the like. When the buffer member 8403, the mounting portion 8402, and other members that contact the skin of the user are configured to be detachable, cleaning and exchange are easy, which is preferable.

The electronic apparatus shown in fig. 21A to 21F includes a housing 9000, a display portion 9001, a speaker 9003, an operation key 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (the sensor has a function of measuring a force, a displacement, a position, a speed, an acceleration, an angular velocity, a rotation speed, a distance, light, liquid, magnetism, temperature, a chemical substance, sound, time, hardness, an electric field, electric current, voltage, electric power, radiation, flow, humidity, inclination, vibration, smell, or infrared rays), a microphone 9008, or the like.

The electronic devices shown in fig. 21A to 21F have various functions. For example, it may have the following functions: a function of displaying various information (still image, moving image, character image, etc.) on the display unit; a function of the touch panel; a function of displaying a calendar, date, time, or the like; functions of controlling processing by using various software (programs); a function of performing wireless communication; a function of reading out and processing the program or data stored in the storage medium; etc. Note that the functions that the electronic device can have are not limited to the above-described functions, but may have various functions. The electronic device may include a plurality of display portions. In addition, a camera or the like may be provided in the electronic device so as to have the following functions: a function of capturing a still image or a moving image, and storing the captured image in a storage medium (an external storage medium or a storage medium built in a camera); a function of displaying the photographed image on a display section; etc.

The display device according to one embodiment of the present invention can be used for the display portion 9001.

Next, the electronic apparatus shown in fig. 21A to 21F will be described in detail.

Fig. 21A is a perspective view showing the portable information terminal 9101. The portable information terminal 9101 can be used as a smart phone, for example. Note that in the portable information terminal 9101, a speaker 9003, a connection terminal 9006, a sensor 9007, and the like may be provided. Further, as the portable information terminal 9101, text and image information may be displayed on a plurality of surfaces thereof. An example of displaying three icons 9050 is shown in fig. 21A. Further, information 9051 shown in a rectangle of a broken line may be displayed on the other face of the display portion 9001. As an example of the information 9051, information indicating the receipt of an email, SNS, a telephone, or the like can be given; a title of an email, SNS, or the like; sender name of email or SNS; a date; time; a battery balance; and display of the antenna received signal strength, etc. Alternatively, the icon 9050 or the like may be displayed at a position where the information 9051 is displayed.

Fig. 21B is a perspective view showing the portable information terminal 9102. The portable information terminal 9102 has a function of displaying information on three or more surfaces of the display portion 9001. Here, examples are shown in which the information 9052, the information 9053, and the information 9054 are displayed on different surfaces. For example, in a state where the portable information terminal 9102 is placed in a coat pocket, the user can confirm the information 9053 displayed at a position seen from above the portable information terminal 9102. The user can confirm the display without taking out the portable information terminal 9102 from the pocket, whereby it can be judged whether or not to receive a call.

Fig. 21C is a perspective view showing the wristwatch-type portable information terminal 9200. The portable information terminal 9200 can be used as a smart watch (registered trademark), for example. The display surface of the display portion 9001 is curved, and can display along the curved display surface. Further, the portable information terminal 9200 can perform handsfree communication by, for example, communicating with a headset capable of wireless communication. Further, by using the connection terminal 9006, the portable information terminal 9200 can perform data transmission and charging with other information terminals. Charging may also be performed by wireless power.

Fig. 21D to 21F are perspective views showing the portable information terminal 9201 that can be folded. Fig. 21D is a perspective view showing a state in which the portable information terminal 9201 is unfolded, fig. 21F is a perspective view showing a state in which it is folded, and fig. 21E is a perspective view showing a state in the middle of transition from one of the state of fig. 21D and the state of fig. 21F to the other. The portable information terminal 9201 has good portability in a folded state and has a large display area with seamless splicing in an unfolded state, so that the display has a strong browsability. The display portion 9001 included in the portable information terminal 9201 is supported by three housings 9000 connected by hinges 9055. The display portion 9001 can be curved in a range of, for example, 0.1mm to 150mm in radius of curvature.

Examples (example)

In this embodiment, a display panel according to one embodiment of the present invention is manufactured.

[ manufacturing of display Panel ]

The display panel was manufactured by the method shown in embodiment 1 and manufacturing method example 1. Specifically, a substrate in which a pixel circuit including a transistor, a wiring, and the like and a pixel electrode are formed over a single crystal silicon substrate is first prepared. Next, after the red EL layer, the green EL layer, and the blue EL layer are sequentially formed, an insulating layer for protecting the side surfaces of each EL layer is formed. Then, the sacrificial layer and the protective layer on each EL layer are removed. Then, an electron injection layer, a common electrode, and a protective layer are sequentially formed on the EL layer.

As a substrate, a single crystal silicon substrate is used, and a single crystal silicon transistor, a wiring layer, an oxide semiconductor transistor (OS transistor), and a light emitting element are stacked in this order to manufacture a display panel. The OS transistor uses an In-Ga-Zn oxide film (IGZO) In the semiconductor layer.

As the EL layer, a stacked-layer structure of a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer is formed. As the sacrificial layer, an aluminum oxide film formed by an ALD method at a substrate temperature of 80 ℃ and a tungsten film formed by a sputtering method were used. As an insulating layer for protecting the side wall of the EL layer, an aluminum oxide film and a photosensitive resin formed by an ALD method are used. A stacked film of a lithium fluoride film and an ytterbium film was used as an electron injection layer, a mixed film of silver and magnesium was used as a common electrode, and an ITO film formed by a sputtering method was used as a protective layer on the common electrode.

In the display panel manufactured in this example, the display portion was square with a diagonal line of 0.99 inches, the effective pixel count was 1920×1920, the definition was 2731ppi, the pixel pitch was 9.3 μm×9.3 μm, the pixel arrangement was RGB stripe arrangement, the aperture ratio was 43% (design value), and the frame rate was 90Hz.

[ display results ]

Fig. 22A and 22B are display photographs of the manufactured display panel. By using a separate coating method without using a metal mask, an extremely high definition and color image with 2731ppi can be realized.

[ Spectrometry ]

The spectrum measurement was performed on the manufactured display panel. The wavelength dependence of the spectroradiometric intensity was measured in a state where all pixels of the display panel were displayed in red (R), green (G), blue (B) and Black (BK) respectively. Here, for comparison, two display panels (comparative example 1 and comparative example 2) using a white OLED and a color filter were evaluated in the same manner. Note that the definition of each of comparative example 1 and comparative example 2 is substantially equal to that of the display panel (described as an example) manufactured in this example.

Fig. 23A, 23B and 23C show the spectral measurement results of examples, comparative example 1 and comparative example 2, respectively. The vertical axes in fig. 24A, 24B, and 24C are logarithmic axes. In each figure, the horizontal axis represents wavelength [ nm ]]The vertical axis represents the spectral radiance [ W/sr/m ] ² /nm]. In fig. 23A, 23B, and 23C, the black display result (BK) is omitted.

When the examples were focused on, it was found that: r, G, B are small in half width and the spectra of the respective colors hardly overlap. As shown in fig. 24A, the light emission was hardly observed in the black display, and thus it was found that the light leakage was extremely small in the black display.

On the other hand, when focusing on comparative example 1, it is clear that: the half-width of the spectrum is greater than in the examples. The blue display (B) showed peaks around 650nm, and the green display (G) showed peaks around 450nm and 620nm, respectively. The peak is presumed to be affected by crosstalk, resulting in a decrease in contrast. Further, as shown in fig. 24B, the black display slightly confirmed light emission in the vicinity of the wavelength 600nm to 700nm, and thus the occurrence of light leakage was confirmed.

In comparative example 2, as shown in fig. 24C, light leakage was not observed at the time of black display, but light emission due to crosstalk was observed in the vicinity of 600nm for blue display (B) and green display (G).

From the above results, it was found that although the display panel manufactured in this example had an extremely high definition of 2731ppi, crosstalk was not confirmed, and the display panel could achieve extremely high contrast and color rendering.

[ description of the symbols ]

100: display device, 101: substrate, 103: pixel, 110: light emitting element, 110B: light emitting element, 110G: light emitting element, 110R: light emitting element, 111: pixel electrode, 111B: pixel electrode, 111C: connection electrode, 111G: pixel electrode, 111R: pixel electrode, 112: EL layer, 112B: EL layer, 112Bf: EL film, 112G: EL layer, 112Gf: EL film, 112R: EL layer, 112Rf: EL film, 113: common electrode, 114: common layer, 121: protective layer, 130: region, 131: insulating layer, 131a: insulating layer, 131af: insulating film, 131ap: insulating layer, 131b: insulating layer, 131bf: insulating film, 143a: resist mask, 143b: resist mask, 143c: resist mask, 144: sacrificial film, 144B: sacrificial film, 144G: sacrificial film, 144R: sacrificial film, 145: sacrificial layer, 145B: sacrificial layer, 145G: sacrificial layer, 145R: sacrificial layer, 201: transistor, 204: connection part, 205: transistor, 209: transistor, 211: insulating layer, 213: insulating layer, 214: insulating layer, 215: insulating layer, 218: insulating layer, 221: conductive layer, 222a: conductive layer, 222b: conductive layer, 223: conductive layer, 225: insulating layer, 228: region, 231: semiconductor layer, 231i: channel formation region, 231n: low resistance region, 240: capacitor, 241: conductive layer, 242: connection layer, 243: insulating layer, 245: conductive layer, 251: conductive layer, 252: conductive layer, 254: insulating layer, 255: insulating layer, 256: plug, 261: insulating layer, 262: insulating layer, 263: insulating layer, 264: insulating layer, 265: insulating layer, 271: plug, 274: plug, 274a: conductive layer, 274b: conductive layer, 280: display module, 281: display unit, 282: circuit part, 283: pixel circuit portion, 283a: pixel circuit, 284: pixel portions 284a: pixel, 285: terminal portion 286: wiring section 290: FPC, 291: substrate, 292: substrate, 301: substrate, 301A: substrate, 301B: substrate, 310: transistor, 310A: transistor, 310B: transistor, 311: conductive layer, 312: low resistance region, 313: insulating layer, 314: insulating layer, 315: element separation layer, 320: transistor, 321: semiconductor layer, 323: insulating layer, 324: conductive layer, 325: conductive layer, 326: insulating layer 327: conductive layer, 328: insulating layer, 329: insulating layer, 331: substrate, 332: insulating layer, 341: conductive layer, 342: conductive layer 343: plug, 400A: display device, 400C: display device, 400D: display device, 400E: display device, 400F: display device, 410: protective layer, 411a: pixel electrode, 411b: pixel electrode, 411c: pixel electrode, 414: insulating layer, 416: protective layer, 416a: EL layer, 416b: EL layer, 416c: EL layer, 417: light shielding layer, 418a: conductive layer, 418b: conductive layer, 418c: conductive layer, 419: resin layer, 420: substrate, 421: insulating layer, 421b: insulating layer, 430a: light emitting element, 430b: light emitting element, 430c: light emitting element, 442: adhesive layer, 443: space, 451: substrate, 452: substrate, 462: display unit, 464: circuit, 465: wiring, 466: conductive layer, 472: FPC, 473: IC. 772: lower electrode, 785: coloring layer, 786: EL layer, 786a: EL layer, 786b: EL layer, 788: upper electrode, 4411: light emitting layer, 4412: light emitting layer, 4413: light emitting layer, 4420: layer, 4420-1: layer, 4420-2: layer, 4430: layer, 4430-1: layer, 4430-2: layer, 6500: electronic device, 6501: frame body, 6502: display unit, 6503: power button, 6504: button, 6505: speaker, 6506: microphone, 6507: camera, 6508: light source, 6510: protection member, 6511: display panel, 6512: optical member, 6513: touch sensor panel, 6515: FPC, 6516: IC. 6517: printed circuit board, 6518: battery, 7000: display unit, 7100: television apparatus, 7101: frame body, 7103: support, 7111: remote control operation machine, 7200: notebook personal computer, 7211: frame, 7212: keyboard, 7213: pointing device, 7214: external connection port, 7300: digital signage, 7301: frame body, 7303: speaker, 7311: information terminal apparatus, 7400: digital signage, 7401: column, 7411: information terminal apparatus, 8000: camera, 8001: frame body, 8002: display unit, 8003: operation button, 8004: shutter button, 8006: lens, 8100: viewfinder, 8101: frame body, 8102: display unit, 8103: button, 8200: head mounted display, 8201: mounting portion, 8202: lens, 8203: main body, 8204: display unit, 8205: cable, 8206: battery, 8300: head mounted display, 8301: frame body, 8302: display unit, 8304: fixing tool, 8305: lens, 8400: head mounted display, 8401: frame body, 8402: mounting portion, 8403: cushioning members, 8404: display section, 8405: lens, 9000: frame body, 9001: display unit, 9003: speaker, 9005: operation key, 9006: connection terminal, 9007: sensor, 9008: microphone, 9050: icon, 9051: information, 9052: information, 9053: information, 9054: information, 9055: hinge, 9101: portable information terminal, 9102: portable information terminal, 9200: portable information terminal, 9201: a portable information terminal.

Claims

1. A display device, comprising:

a first pixel;

a second pixel disposed adjacent to the first pixel; and

a first insulating layer is provided over the first insulating layer,

wherein the first pixel comprises a first pixel electrode, a first EL layer on the first pixel electrode and a common electrode on the first EL layer,

the second pixel includes a second pixel electrode, a second EL layer on the second pixel electrode, and the common electrode on the second EL layer,

the side of the first EL layer and the side of the second EL layer have regions in contact with the first insulating layer,

the side of the first pixel electrode is covered by the first EL layer,

and, the side surface of the second pixel electrode is covered with the second EL layer.

2. The display device according to claim 1, wherein a top surface of the first EL layer, a top surface of the second EL layer, and a top surface of the first insulating layer have regions in contact with the common electrode.

3. The display device according to claim 1,

wherein the first pixel includes a common layer disposed between the first EL layer and the common electrode,

the second pixel includes the common layer disposed between the second EL layer and the common electrode,

And the top surface of the first EL layer, the top surface of the second EL layer, and the top surface of the first insulating layer have areas in contact with the common layer.

4. A display device according to any one of claims 1 to 3, wherein the first insulating layer has a region protruding upward compared to at least one of a top surface of the first EL layer and a top surface of the second EL layer when viewed in a cross section of the display device.

5. A display device according to any one of claims 1 to 3, wherein at least one of the first EL layer and the second EL layer has a region protruding upward from a top surface of the first insulating layer when seen in a cross section of the display device.

6. A display device according to any one of claims 1 to 3, wherein a top surface of the first insulating layer has a concave curved surface shape when viewed in a cross section of the display device.

7. A display device according to any one of claims 1 to 3, wherein a top surface of the first insulating layer has a convex curved shape when viewed in a cross section of the display device.

8. A display device, comprising:

a first pixel;

a second pixel disposed adjacent to the first pixel;

A first insulating layer; and

a second insulating layer is provided over the first insulating layer,

the second insulating layer is disposed on and in contact with the first insulating layer and is disposed under the common electrode,

the first insulating layer comprises an inorganic material,

the second insulating layer comprises an organic material,

the side of the first pixel electrode is covered by the first EL layer,

9. The display device according to claim 8, wherein a top surface of the first EL layer, a top surface of the second EL layer, and a top surface of the first insulating layer have regions in contact with the common electrode.

10. The display device according to claim 8,

11. The display device according to any one of claims 8 to 10, wherein the first insulating layer has a region protruding upward compared to at least one of a top surface of the first EL layer and a top surface of the second EL layer when viewed in a cross section of the display device.

12. The display device according to any one of claims 8 to 10, wherein at least one of the first EL layer and the second EL layer has a region protruding upward from a top surface of the first insulating layer when seen in a cross section of the display device.

13. The display device according to any one of claims 8 to 10, wherein a top surface of the second insulating layer has a concave curved surface shape when viewed in a cross section of the display device.

14. The display device according to any one of claims 8 to 10, wherein a top surface of the second insulating layer has a convex curved surface shape when viewed in a cross section of the display device.