electronic machinery

Abstract

One aspect of the present invention aims to provide a novel display device or display system. Another aspect of the present invention aims to provide a display device or display system that can be manufactured at low cost and can provide users with a variety of multi-functional capabilities. [Solution] Each pixel has a light-emitting element with a different emission color from each other, a light-emitting element IR, a photodetector PS, and an infrared light sensor IRS. Fundus imaging is performed using a light-emitting element that emits infrared light as a light source and imaging with the photodetector IRS. The substrate of the display panel is made using a single-crystal Si substrate that allows for microfabrication and high integration.

Description

[Technical Field]

[0001] The present invention relates to semiconductor devices and methods for manufacturing the same. One aspect of the present invention particularly relates to electronic devices and display systems that utilize the organic electroluminescence (EL) phenomenon.

[0002] In this specification, the term "semiconductor device" refers to all devices that can function by utilizing semiconductor properties, and electro-optical devices, semiconductor circuits, and electronic devices are all considered semiconductor devices. [Background technology]

[0003] A wide variety of display devices are available on the market, ranging from large display devices like television sets to small display devices like wristwatches. In recent years, mobile phones such as smartphones, tablet devices, and notebook PCs (personal computers) have become widely popular. Display devices that use a head-mounted or glasses-type system (Patent Document 1) have also been developed.

[0004] Furthermore, light-emitting elements that utilize the EL phenomenon are known. Because these light-emitting elements are self-emissive, they have high contrast and a fast response speed to input signals. And a display device that utilizes this light-emitting element is known that has reduced power consumption, a simple manufacturing process, and can easily accommodate high resolution and larger substrates (Patent Document 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2016-110117 [Patent Document 2] Japanese Patent Publication No. 2011-238908 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] An aspect of one embodiment of the present invention aims to provide a novel display device or display system. Another aspect of one embodiment of the present invention aims to provide a display device or display system that can be manufactured at low cost and can provide various multifunctions to a user. Another aspect of one embodiment of the present invention aims to provide a display device or display system that can obtain information of a user's eye. MEANS FOR SOLVING THE PROBLEMS

[0007] A configuration disclosed in this specification is an electronic device to be worn on a user's head, which includes a display device having a transistor, a light-emitting element, and a light-receiving element over the same substrate or on the same substrate, and the display device is an electronic device having a function of displaying an image and a function of imaging a user's fundus.

[0008] In the above configuration, the light-emitting element is an organic light-emitting element that emits visible light. Light emitted from the organic light-emitting element is red, green, blue, or white.

[0009] Moreover, in the above configuration, the light-emitting element is an organic light-emitting element that emits invisible light. For example, it is an organic light-emitting element that emits infrared light.

[0010] In each of the above configurations, single crystal silicon is used for a semiconductor layer of the transistor. When single crystal silicon is used for the semiconductor layer of the transistor, a single crystal Si substrate is used, and an n-type or p-type impurity element is doped by a known method to form a low-resistance region.

[0011] In each of the above configurations, an oxide semiconductor is used for a semiconductor layer of the transistor. When the oxide semiconductor is used for the semiconductor layer of the transistor, film formation is performed over a substrate by a sputtering method.

[0012] In each of the above configurations, the electronic device includes the light-emitting element and the light-receiving element, and can obtain a fundus image by imaging a user's eye to perform diagnosis.

[0013] In this specification, devices fabricated using a metal mask or an FMM (Fine Metal Mask, a high-resolution metal mask) may be referred to as MM (Metal Mask) structured devices. In this specification, devices fabricated without using a metal mask or an FMM may be referred to as MML (Metal Maskless) structured devices.

[0014] In this specification, a structure in which different light-emitting layers are created or painted for each color of light-emitting device (here, blue (B), green (G), and red (R)) may be referred to as an SBS (Side By Side) structure. Also, in this specification, a light-emitting device capable of emitting white light may be referred to as a white light-emitting device. A white light-emitting device can be combined with a colored layer (for example, a color filter) to realize a full-color display light-emitting device.

[0015] Furthermore, light-emitting devices can be broadly classified into single-structure and tandem-structure devices. A single-structure device has one light-emitting unit between a pair of electrodes, and it is preferable that this light-emitting unit includes one or more light-emitting layers. To obtain white light emission, one should select light-emitting layers such that the light emitted from each of the two or more layers is complementary in color. For example, by making the light-emitting color of the first light-emitting layer and the light-emitting color of the second light-emitting layer complementary, a configuration that emits white light as a whole can be obtained. The same applies to light-emitting devices having three or more light-emitting layers.

[0016] A tandem device preferably has two or more light-emitting units between a pair of electrodes, and each light-emitting unit preferably includes one or more light-emitting layers. To obtain white light emission, the light from the light-emitting layers of the multiple light-emitting units should be combined to produce white light emission. The configuration for obtaining white light emission is the same as for a single-structure device. In a tandem device, it is preferable to provide an intermediate layer of charge generation layer between the multiple light-emitting units.

[0017] Furthermore, when comparing the aforementioned white light-emitting devices (single or tandem structure) with light-emitting devices with an SBS structure, the SBS structure light-emitting device can consume less power than the white light-emitting device. Therefore, when minimizing power consumption is desired, the SBS structure light-emitting device is preferable. On the other hand, the white light-emitting device is preferable because its manufacturing process is simpler than that of the SBS structure light-emitting device, allowing for lower manufacturing costs or higher manufacturing yields. [Effects of the Invention]

[0018] According to one aspect of the present invention, an electronic device capable of accurately recognizing the user's visual information can be provided. Alternatively, according to one aspect of the present invention, a novel electronic device can be provided. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1A is a conceptual cross-sectional view of a display device and an eye illustrating one aspect of the present invention, Figure 1B is a schematic diagram showing a retinal pattern, and Figure 1C is a perspective view of a display panel. [Figure 2] Figure 2A is a perspective view of a display panel showing one embodiment of the present invention, and Figures 2B and 2C are schematic top views showing examples of pixel arrangement. [Figure 3] Figure 3A is a schematic cross-sectional view showing one embodiment of the present invention, and Figures 3B and 3C are schematic external views of the electronic device. [Figure 4] Figures 4A, 4B, and 4C are schematic cross-sectional views of a display panel illustrating one aspect of the present invention. [Figure 5] Figures 5A, 5B, and 5C are schematic diagrams of a display panel showing one embodiment of the present invention. [Figure 6] Figure 6 is a perspective view of an electronic device showing one aspect of the present invention. [Figure 7] Figure 7A is a top view showing an example of pixel arrangement in one aspect of the present invention, and Figure 7B is a schematic cross-sectional view of a display panel. [Figure 8] Figure 8 is a schematic top view showing one embodiment of the present invention. [Figure 9] Figure 9 is a cross-sectional view showing an example of the configuration of a semiconductor device. [Figure 10] Figure 10 is a cross-sectional view showing an example of the configuration of a semiconductor device. [Figure 11] Figure 11 is a cross-sectional view showing an example of the configuration of a semiconductor device. [Figure 12] Figure 12 is a cross-sectional view showing an example of the configuration of a semiconductor device. [Figure 13] Figure 13 is a cross-sectional view showing an example of the configuration of a semiconductor device. [Figure 14] Figure 14 is a cross-sectional view showing an example of the configuration of a semiconductor device. [Figure 15] Figures 15A to 15D illustrate examples of the configuration of a light-emitting element. [Figure 16] Figures 16A to 16D show examples of display device configurations. [Figure 17] Figures 17A to 17D show examples of display device configurations. [Figure 18] Figure 18A is a top view showing an example of a transistor configuration. Figures 18B and 18C are cross-sectional views showing an example of a transistor configuration. [Figure 19] Figure 19A illustrates the classification of IGZO crystal structures. Figure 19B illustrates the XRD spectrum of a CAAC-IGZO film. Figure 19C illustrates the micro-electron diffraction pattern of a CAAC-IGZO film. [Modes for carrying out the invention]

[0020] Embodiments of the present invention will be described in detail below with reference to the drawings. However, it will be readily apparent to those skilled in the art that the present invention is not limited to the following description, and its form and details can be modified in various ways. Furthermore, the present invention is not to be interpreted as being limited to the embodiments described below.

[0021] In the configuration of the invention described below, the same reference numerals are used in common across different drawings for identical parts or parts having similar functions, and repeated explanations are omitted. Furthermore, when referring to similar functions, the hatch patterns are the same, and reference numerals may not be assigned.

[0022] In the figures described herein, the size of each component, the thickness of the layers, or the area may be exaggerated for clarity. Therefore, the scale is not necessarily limited to those figures.

[0023] In this specification, the ordinal numbers "1st" or "2nd" are used to avoid confusion of constituent elements and do not imply any numerical limitation.

[0024] Furthermore, in this specification, the terms "above," "below," "left," and "right" are used for convenience to explain the positional relationships between components with reference to the drawings. The positional relationships between components change as appropriate depending on the direction in which each component is depicted. Therefore, the terms used are not limited to those described in this specification and can be appropriately rephrased depending on the situation.

[0025] A transistor is a type of semiconductor device that can perform switching operations to amplify current or voltage, or to control conduction or non-conductivity. Transistors as used herein include IGFETs (Insulated Gate Field Effect Transistors) or Thin Film Transistors (TFTs).

[0026] Furthermore, in this specification, the source and drain functions of a transistor may be reversed if the polarity of the transistor or the direction of current changes during circuit operation. For this reason, the terms source and drain may be used interchangeably.

[0027] Furthermore, in this specification, "electrically connected" includes both direct connections and connections made via "something that has some electrical function." Here, "something that has some electrical function" is not particularly limited as long as it enables the exchange of electrical signals between the connected objects. Therefore, even when it is expressed as "electrically connected," in a real circuit there may be no physical connection part, only wiring extending from there. Also, even when it is expressed as "direct connection," it includes cases where different conductors are connected via contacts. Note that the wiring may contain different conductors that contain one or more of the same element, or different elements.

[0028] Furthermore, unless otherwise specified in this specification, off-current refers to the drain current when the transistor is in the off state (also called the non-conducting state or cutoff state). Unless otherwise specified, the off state in an n-channel transistor is defined as the voltage V between the gate and source. gs The threshold voltage V th Lower than (in p-channel transistors, V th This refers to a state that is higher than [a certain value].

[0029] Furthermore, the terms “electrode” or “wiring” in this specification do not functionally limit these components. For example, “electrode” may be used as part of “wiring,” and vice versa. Moreover, the terms “electrode” or “wiring” also include cases where multiple “electrodes” or “wiring” form a single unit.

[0030] Furthermore, in this specification, the resistance value of "resistance" may be determined by the length of the wiring. Alternatively, the resistance value may be determined by connecting to a conductor having a different resistivity than the conductor used in the wiring. Alternatively, the resistance value may be determined by doping the semiconductor with impurities.

[0031] Furthermore, in this specification, "terminal" in an electrical circuit refers to a part where current or voltage is input or output, or where signals are received or transmitted. Therefore, a part of the wiring or electrodes may function as a terminal.

[0032] In this specification, "metal oxide" refers to an oxide of a metal in a broad sense. Metal oxides are classified into oxide insulators, oxide conductors (including transparent oxide conductors), and oxide semiconductors (also called Oxide Semiconductors or simply OS). For example, when a metal oxide is used in the active layer of a transistor, that metal oxide may be referred to as an oxide semiconductor. In other words, when OS FET is mentioned, it can be rephrased as a transistor having a metal oxide or oxide semiconductor.

[0033] (Embodiment 1) In this embodiment, an electronic device according to one aspect of the present invention will be described with reference to the drawings.

[0034] Figure 1A is a schematic diagram showing the positional relationship between the display panel 280 and the user's eyes. The display panel 280 has multiple light-emitting elements and multiple light-receiving elements. The light emitted 951 from the light-emitting elements of the display panel 280 is shone onto the eye via the optical system 950, and the reflected light is received by the light-receiving elements to take images of the area around the eye, the surface of the eye, or the inside of the eye (fundus). For example, the display panel 280 shown in Figure 1A has light-emitting elements and light-receiving elements, so it can capture images of the fundus via the optical system 950 and acquire image data of the retinal pattern. However, if the focus is adjusted with the optical system 950, it becomes difficult to capture other areas. For example, if the focus is on the fundus, the area around the eye will not be in focus and therefore almost impossible to capture.

[0035] The user's eye is composed of the lens 942, retina 941, optic nerve 943, vitreous humor 947, choroid 948, and cornea. The pupil is located between the cornea and the lens, but for simplicity, the cornea and pupil are not shown. The ciliary body is a tissue that extends from the iris, and the choroid 948 is a tissue that extends from the ciliary body. The iris and pupil function like the aperture of a camera, adjusting the amount of light that illuminates the retina 941. The pattern of the retina 941, the so-called retinal pattern, is said to remain essentially unchanged from birth to death, and personal identification can be performed using this retinal pattern. The retinal pattern obtained from the display panel 280 can be used to diagnose the eye remotely.

[0036] Figure 1B shows an example of the retinal pattern of the right eye. The retina 941 shows the optic nerve head 944, vein 945, artery 946, macula, or fovea. The optic nerve head 944 refers to the boundary between the optic nerve 943 and the retina 941, and the vein 945 and artery 946 are positioned to extend from the optic nerve head 944. The fundus refers to the back part of the eyeball and is a collective term for the retina 941, vitreous humor 947, choroid 948, and optic nerve head 944. In the case of the left eye, the optic nerve head 944 is located on the left side of the retinal pattern, resulting in a retinal pattern that is a horizontal reversal of the right eye retinal pattern in Figure 1B.

[0037] To acquire the retinal pattern of the fundus using the light-receiving element of the display panel 280, the pupil needs to be dilated. To dilate the pupil and image the fundus, change the display in the following steps: Gradually dilate the display screen of the display panel 280 to allow the user's eyes to adapt to the dark. Brighten the display screen for a short time of 16.7 ms or less and take an image. Then, gradually return the display screen to its original brightness.

[0038] Furthermore, the display panel 280 can be used to detect the user's eye fatigue level. When the display screen is brightened and imaging is performed for a certain period of time, the image cannot be captured if the user blinks. Therefore, by detecting the number of blinks, the timing, or the duration of eye closure, the system can use AI (Artificial Intelligence) to estimate the user's eye fatigue level based on the frequency of blinks, the intervals between blinks, or the duration of eye closure.

[0039] Furthermore, images may be taken multiple times while the display screen of the display panel 280 is darkened. By taking multiple images, the pulsation of retinal blood vessels can be detected, and the user's resting or tense state can also be determined using an AI-based system. In addition, hypertension or diabetes can be diagnosed using an AI-based system based on the various data obtained from the display panel 280. When using an AI-based system, a control circuit is installed in the display panel 280. The control circuit uses a CPU (Central Processor Unit) or a GPU (Graphics Processing Unit). Alternatively, an APU (Accelerated Processing Unit), which integrates the CPU and GPU into a single chip, can be used for the control circuit. An IC (also called an inference chip) with an AI system built in may also be used. An IC with an AI system built in is sometimes called a circuit (microprocessor) that performs neural network calculations.

[0040] Alternatively, the direction of the eyeballs may be controlled by displaying an eye-catching pattern on the display screen of the display panel 280 while the display screen of the display panel 280 is dimmed.

[0041] The distance between the display panel 280 and the surface of the eye (e.g., the cornea) should ideally be approximately 2 cm or less. To achieve this positional relationship, an optical system 950 with a short focal length is placed between the display panel 280 and the eye.

[0042] When the screen is magnified 10 times by the optical system 950, for example, if the display screen size of the display panel 280 is approximately 1 inch diagonally, the sensor pixel pitch becomes approximately 10.4 μm. However, the diameters of the retinal veins 945 or arteries 946 are smaller than approximately 100 μm, and can be imaged.

[0043] Figure 1C shows a perspective view of the display panel 280. The display panel 280 includes a display device 400C and an FPC 290. The display panel 280 can also be called a system display.

[0044] The display panel 280 has substrates 291 and 292. The display panel 280 has a pixel section 284. The pixel section 284 is the area on the display panel 280 where the image is displayed, and is the area where light from each pixel provided in the pixel section 284, which will be described later, can be seen.

[0045] Figure 2A shows a schematic perspective view illustrating the configuration of the substrate 291. On the substrate 291, a circuit section 282, a pixel circuit section 283 on the circuit section 282, and a pixel section 284 on the pixel circuit section 283 are stacked. In addition, a terminal section 285 for connecting to the FPC 290 is provided in the portion of the substrate 291 that does not overlap with the pixel section 284. The terminal section 285 and the circuit section 282 are electrically connected by a wiring section 286, which is composed of multiple wires.

[0046] The pixel section 284 has multiple pixels 284a arranged periodically. A magnified view of one pixel 284a is shown on the right side of Figure 2A. The pixel 284a has light-emitting elements 430a, 430b, and 430c with different emission colors, a light-emitting element 430IR, a photodetector 430PS, and an infrared light sensor 430IRS. The light-emitting elements 430a, 430b, and 430c are arranged in a stripe pattern as shown in Figure 2A, but are not particularly limited. Figure 2B shows an example of the arrangement of pixels 284a. In Figure 2B, an example is shown in which a green (G) light-emitting element, a blue (B) light-emitting element, a red (R) light-emitting element, a light-emitting element 430IR, a photodetector 430PS, and an infrared light sensor 430IRS are arranged.

[0047] It is preferable to use EL elements such as OLED (Organic Light Emitting Diode) or QLED (Quantum-dot Light Emitting Diode) as the light-emitting elements 430a, 430b, 430c and 430IR. Examples of light-emitting materials for EL elements include fluorescent materials, phosphorescent materials, inorganic compounds (quantum dot materials), and thermally activated delayed fluorescence (TADF) materials. In addition, LEDs such as microLEDs (Light Emitting Diodes) can be used as light-emitting elements.

[0048] The light-emitting element 430IR emits invisible light. Here, an example is shown in which the light-emitting element 430IR emits infrared light (IR). The photodetector element 430PS is a photoelectric conversion element that is sensitive to at least the infrared light emitted by the light-emitting element 430IR.

[0049] The photodetector 430PS may, for example, have sensitivity within a wavelength range of 700 nm to 900 nm. Furthermore, it is preferable that the photodetector 430PS is sensitive not only to infrared light but also to the light emitted by the light-emitting element 430IR and the light-emitting elements 430a, 430b, and 430c, respectively. If the photodetector 430PS is sensitive to both visible and infrared light, it is preferable that it has sensitivity within a wavelength range of 500 nm to 1000 nm, 500 nm to 950 nm, or 500 nm to 900 nm.

[0050] As the light-receiving element 430PS, for example, a pn-type or pin-type photodiode can be used. The light-receiving element functions as a photoelectric conversion element that detects light incident on it and generates an electric charge. The amount of charge generated by the photoelectric conversion element is determined by the amount of incident light. In particular, it is preferable to use an organic photodiode (OPD) having a layer containing an organic compound as the light-receiving element 430PS. This allows for the partial commonality of production equipment, manufacturing devices, and materials that can be used for manufacturing the first light-emitting element, the second light-emitting element, and the light-receiving element, thereby reducing manufacturing costs. Furthermore, these manufacturing processes can be simplified, improving manufacturing yield. Organic photodiodes are easy to thin, lighten, and enlarge in area, and offer a high degree of freedom in shape and design, making them applicable to various display devices.

[0051] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0052] A single pixel circuit 283a is a circuit that controls the light emission of the three light-emitting elements of a single pixel 284a. A single pixel circuit 283a may be configured to have three circuits that control the light emission of a single light-emitting element. For example, a single pixel circuit 283a may have at least one selection transistor, one current control transistor (drive transistor), and a capacitive element for each light-emitting element. In this case, a gate signal is input to the gate of the selection transistor, and a source signal is input to either the source or the drain. This realizes an active-matrix type display device.

[0053] The circuit section 282 has circuits for driving each pixel circuit 283a of the pixel circuit section 283. For example, it is preferable to have one or both of a gate line drive circuit and a source line drive circuit. In addition, it may have at least one of an arithmetic circuit, a memory circuit, a control circuit, and a power supply circuit.

[0054] The FPC290 functions as wiring for supplying video signals or power potential to the circuit section 282 from an external source. An IC may also be mounted on the FPC290.

[0055] The display panel 280 can be configured such that one or both of the pixel circuit section 283 and the circuit section 282 are stacked on the lower side of the pixel section 284, thereby making the aperture ratio (effective display area ratio) of the pixel section 284 extremely high. For example, the aperture ratio of the pixel section 284 can be 40% or more and less than 100%, preferably 50% or more and 95%, and more preferably 60% or more and 95%. Furthermore, it is possible to arrange the pixels 284a at an extremely high density, making the resolution of the pixel section 284 extremely high. For example, it is preferable that the pixels 284a in the pixel section 284 are arranged with a resolution of 20000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and with a resolution of 20000 ppi or less, or 30000 ppi or less.

[0056] Furthermore, Figure 2C shows an example of a pixel section 284b that is different from the pixel section 284a in Figure 2B. In Figure 2C, in addition to the green (G), blue (B), and red (R) light-emitting elements, a white (W) light-emitting element is also provided.

[0057] Figure 3A shows an example of a cross-sectional view of an electronic device 80 having a display device according to one embodiment of the present invention. Figure 3C shows an example of the electronic device 80 in a glasses-type configuration, and Figure 3B shows an example of it being worn by a user. Although not shown in Figure 3B, the electronic device 80 has a secondary battery for powering the display panel 280.

[0058] The display panel 280 shown in Figure 3A corresponds to the cross-sectional structure between the dashed lines A1 and A2 in Figure 2B. The electronic device 80 shown in Figure 3A has the display panel 280 between the housing 103 and the protective member 105. The display panel 280 has a plurality of light-emitting elements and a plurality of light-receiving elements between the substrate 291 and the substrate 292. Here, Figures 3A and 3B are schematic diagrams illustrating the functions of the electronic device 80 as a display device and as an image-capturing device (the fundus of the user's 81).

[0059] The electronic device 80 uses a light-emitting element 130R that emits red light 951R, a light-emitting element 130G that emits green light 951G, and a light-emitting element 130B that emits blue light 951B for full-color display, and for fundus imaging, a light-emitting element that emits infrared light 951IR is used as the light source, and imaging is performed with a photodetector IRS.

[0060] Furthermore, the photodetector PS can receive reflected light or ambient light that is RGB, allowing it to detect the brightness around the eye and confirm whether it is dark before photographing the fundus. If this confirmation is not necessary, the photodetector PS does not need to be provided.

[0061] An optical system is installed in the region where a light-emitting element that emits infrared light (951IR) and a photodetector (IRS) overlap, so as to focus on the fundus of the eye.

[0062] In Figure 3A, the substrate 291 of the display panel 280 may be made by forming a switching element on a glass substrate or a plastic substrate, and then forming an organic light-emitting diode (OEL) element or a photodetector that is electrically connected to the switching element on top of it. However, it is preferable to use a single-crystal Si substrate that allows for microfabrication and high integration.

[0063] Furthermore, examples of the configuration of the display panel 280 mounted on the electronic device 80 are shown in Figures 4A, 4B, and 4C. Note that Figures 4A, 4B, and 4C correspond to Figure 1A, and the same reference numerals are used for the same parts.

[0064] Figure 4A shows an example of forming a switching element using an oxide semiconductor (OS) on a single-crystal Si substrate on which a display panel drive circuit has been fabricated, and then forming an organic light-emitting diode (OEL) element electrically connected to the switching element. When creating a high-definition display, the current flowing through the drive transistor of each pixel is at the nanoampere level, and since silicon transistors would draw too much current, OS transistors are suitable. Also, when displaying black, a low off-current is preferable, and OS transistors with low off-currents are suitable. Furthermore, when using organic EL elements, a voltage withstand voltage of 10V or more is preferably required, and OS transistors are more suitable than silicon transistors. The light emitted 951 from the organic EL element (OEL) allows the user to perceive the image display. In addition, by forming an infrared light-emitting element (IR) and a photodetector (OPD) on the layer having the organic EL element, fundus photography can be performed by emitting infrared light, reflecting it off the user's fundus, and receiving the light with the OPD. Alternatively, a light-receiving element may be fabricated on a single-crystal Si substrate, and fundus photography may be performed by emitting infrared light and receiving the reflected light from the user's fundus with a photodiode containing silicon in the light-receiving area.

[0065] Figure 4B also shows an example of bonding two single-crystal Si substrates. A first single-crystal Si substrate with a drive circuit or control circuit fabricated on it and a second single-crystal Si substrate with a switching element that electrically connects to an organic light-emitting diode (OEL) fabricated on it are bonded together using known techniques. Alternatively, a photodetector may be fabricated on the second single-crystal Si substrate, and fundus photography may be performed by emitting infrared light and receiving the reflected light from the user's fundus with a photodiode containing silicon in the light-receiving region.

[0066] In Figure 4B, the external world is displayed as an image captured by an external camera 91 installed on the electronic device 80 shown in Figure 3C. While it is difficult to align the display position in AR methods, recognizing the image captured by the external camera 91 makes it possible to augment reality. Furthermore, a battery 92 may be provided in the temple portion of the glasses on the electronic device 80. This battery 92 has the function of supplying power to the external camera 91 or the display panel 280.

[0067] Figure 4C also shows an example of thinning a single-crystal Si substrate. In Figure 4C, a photodetector and a switching element that electrically connects to an organic light-emitting diode (OEL) element are fabricated into the single-crystal Si substrate, and the drive circuit or control circuit is externally mounted.

[0068] Furthermore, in Figures 4A and 4C, if the thickness of the single-crystal Si substrate is thin, visible light can also be transmitted. Therefore, it is possible to create an AR-type electronic device that transmits ambient light.

[0069] Furthermore, Figures 5A, 5B, and 5C show examples of variations in the size of the display panel 280. Although the peripheral shape of the display panel 280 in Figures 5A, 5B, and 5C is shown as rectangular, it is not particularly limited and may be circular or elliptical.

[0070] Figure 5A shows an example where the display panel 280 is attached to the user's head and overlaps only one of the user's eyes, resulting in a monocular system. Note that to photograph the fundus of both eyes, two electronic devices are required: one for the right eye and one for the left eye. In Figure 5A, using a single-crystal Si substrate for the display panel 280 reduces manufacturing costs due to its small size. As shown in Figure 8A, multiple chips can be obtained from a single silicon wafer. For example, using a 12-inch silicon wafer with a chip size of 26mm x 16.5mm, 142 chips can be obtained from one wafer. A single chip can produce a display panel with a screen size of 19.9mm x 14.9mm (0.99-inch diagonal), with a resolution of 2449ppi using 1920 x 1440 pixels. Furthermore, the entire electronic device can be made lightweight when the display panel 280 is attached to the user's head.

[0071] Figure 5B shows an example of a spectacle-type system in which a display panel 280R for the right eye and a display panel 280L for the left eye are provided separately.

[0072] Figure 5C shows an example where a single display panel 280 overlaps both eyes, and the screen size has a larger area than in other examples. Because the area of ​​the display panel 280 is large, there is a wide margin for eye alignment, which can accommodate individual differences in users.

[0073] In the examples shown in Figures 5A, 5B, and 5C, significant miniaturization and weight reduction can be achieved compared to conventional ophthalmic diagnostic devices.

[0074] The eye has aberrations, and the image displayed on the screen is not perfectly projected onto the retina. The brain constructs the image through learning. Conversely, retinal patterns do not project clear patterns onto the sensor as they do onto conventional ophthalmic diagnostic devices. Furthermore, AI-powered systems can be used for authentication or health monitoring.

[0075] When using AI-based systems, the calculation process can be performed within the electronic device itself, the captured image data can be transmitted externally via a network and calculated by an external computing device, or a combination of these methods can be employed.

[0076] When performing some or all of the calculation processing within an electronic device, it is necessary to provide a control circuit on the single-crystal Si substrate shown in Figures 4A, 4B, and 4C. Alternatively, when performing only a portion of the calculation processing, the calculation circuit may be formed using transistors made of oxide semiconductors (OS).

[0077] When transmitting data externally, a data transmission and reception circuit is installed in the electronic device, and an AI-based system is used.

[0078] Furthermore, the system may be configured to communicate with the user's personal digital assistant (PDCA) device. If the PDCA device has downloaded an application that utilizes an AI-powered system, authentication or health monitoring can be performed by exchanging data with the PDCA device.

[0079] As an example of health monitoring, eye health can be monitored using the display panel 280.

[0080] The fundus is periodically imaged while the user is wearing an electronic device with a display panel 280. During fundus imaging, the display is dimmed to allow the user's eyes to adapt to the dark. During this period, the time when imaging is not possible is due to blinking or the eyes being closed. Therefore, data on the number or duration of blinks during this period is acquired and stored. In addition, the user also inputs the degree of their subjective symptoms of eye strain when acquiring data, creating training data. Based on the accumulated data, eye strain or eye abnormalities can be detected using an AI-powered system.

[0081] Furthermore, while Figure 3B shows an example of a glasses-type electronic device 80, it is not particularly limited as long as it is worn on the head, and as shown in Figure 6, it may be equipped with a display panel 280 of an electronic device 80 called a head-mounted display (HMD). Also, the electronic device 80 can be called a goggle-type electronic device.

[0082] Figure 6 shows an example where a display panel 280 overlaps with both eyes, as shown in Figure 5C.

[0083] The electronic device 80 comprises a housing 31, a display panel 280, a fixing device 34, a battery 37, a pair of optical elements (optical elements 35a and 35b), and a pair of frames (frames 36a and 36b). The battery 37, which powers the electronic device 80, supplies power to each part of the electronic device 80 via cables that are built into or attached to the fixing device 34. The battery 37 may be installed in the housing 31, but installing it in the fixing device 34 is preferable because it allows the center of gravity of the electronic device 80 to be moved to the rear, improving the user's wearing comfort. In addition to the battery 37, a drive circuit for operating the display panel 280 may also be installed in the fixing device 34 to adjust the center of gravity of the electronic device 80.

[0084] Furthermore, the electronic device 80 is provided with an opening 32, and optical members 35a, 35b and frames 36a, 36b are provided so as to be in contact with the opening 32. The frames 36a, 36b are in contact with the sides of the optical members 35a, 35b and are provided so as to surround the optical members 35a, 35b, respectively. The display panel 280 can also be provided inside the housing 31.

[0085] The display panel 280 has the function of displaying images. The images displayed on the display panel 280 can be viewed by the user of the electronic device 80 through the optical members 35a and 35b. Preferably, the display panel 280 has the function of displaying high-definition images. For example, when the size of the display area is 8 inches, it is preferable that the display panel 280 has the function of displaying images with a resolution of 8K4K.

[0086] The user of the electronic device 80 can view the image displayed on the display panel 280 through the optical elements 35a and 35b. The electronic device 80 can be an electronic device capable of VR display.

[0087] The display panel 280 also has a function to detect light. The display panel 280 is equipped with a light-receiving element, which is a photoelectric conversion element.

[0088] Light emitted from the light-emitting elements of the display panel 280 can be shone, for example, onto the face of the user of the electronic device 80, and the reflected light can be detected by the light-receiving elements of the display panel 280. For example, the display panel 280 can have a function to detect the state of the eyes and surrounding area of ​​the user wearing the electronic device 80. Therefore, the electronic device 80 can have a function to recognize the user's facial expression and facial features, and can therefore have a function to estimate the user's fatigue level and emotions. The electronic device 80 can, for example, detect watery eyes, blinks, or gaze.

[0089] The display panel 280 preferably has a light-emitting element separate from the light-emitting element for display, for example, an element that emits infrared light, for example, near-infrared light. In this case, the light-receiving element of the display panel 280 preferably has a function to detect infrared light, for example, near-infrared light. This allows the electronic device 80 to image the user's fundus.

[0090] (Embodiment 2) In this embodiment, instead of using an OPD, a light-emitting diode (LED) is used as the light source 104.

[0091] Furthermore, Figure 7A shows an example of a pixel section 284c that is different from the pixel section 284a in Figure 2B. In Figure 7A, in addition to the green (G), blue (B), and red (R) light-emitting elements, an infrared light sensor IRS is also provided.

[0092] The display panel 280 shown in Figure 7B corresponds to the cross-sectional structure between the dashed lines A3 and A4 in Figure 7A. The display panel 280 is located between the housing 103 and the protective member 105. Here, the display panel 280 shown in Figure 7B has the function of a display device and the function of imaging an object (the face, iris, or fundus of the user 81). Also, Figures 7A and 7B use a light-emitting diode (LED) as the light source 104. Figure 7B shows an example in which the light source 104 is positioned so as not to overlap with the display panel 280. In this case, the light emitted 951IR from the light source 104 is emitted to the outside of the electronic device via the protective member 105. The display panel 280 has a plurality of light-emitting devices and a plurality of light-receiving devices between the substrate 106 and the substrate 102. The sub-pixel (R) has a light-emitting device 130R that emits red light 951R. The sub-pixel (G) has a light-emitting device 130G that emits green light 951G. Sub-pixel (B) has a light-emitting device 130B that emits blue light 951B. By using these sub-pixels, a full-color image can be displayed on the display panel 280. Sub-pixel (PS) has a light-receiving device 150PS that receives light 32RGB. In addition, the infrared light 951IR emitted by the light source 104 is reflected by an object (in this case, the fundus of the eye), and the reflected light 32IR from the object is incident on the light-receiving device 150IRS. Although the object is not in contact with the electronic device, it can be detected using the light-receiving device 150IRS.

[0093] When using the display panel 280 shown in Figure 7B, full-color imaging uses light-emitting elements 130R that emit red light 951R, 130G that emit green light 951G, and 130B that emit blue light 951B as light sources, while infrared imaging uses a light-emitting element that emits infrared light 951IR as the light source.

[0094] By making the optical system of the electronic device detachable, it is possible to switch between full-color display and fundus imaging.

[0095] This embodiment can be freely combined with other embodiments.

[0096] (Embodiment 3) In this embodiment, an example of the cross-sectional configuration of the semiconductor device 100A that constitutes the display panel 280 corresponding to Figure 4A will be described.

[0097] Figure 9 is a cross-sectional view showing an example of the configuration of the semiconductor device 100A, and shows a part of the semiconductor device 100A. As mentioned above, the semiconductor device 100A is composed of layer 10, layer 20, layer 30, layer 60, and the sealing substrate 40.

[0098] [Layer 10] Layer 10 has a substrate 701, on which a transistor 431 is provided. Transistor 431 is, for example, a transistor provided in a memory cell.

[0099] A single-crystal semiconductor substrate, such as a single-crystal silicon substrate, can be used as the substrate 701. Alternatively, a semiconductor substrate other than a single-crystal semiconductor substrate may be used as the substrate 701.

[0100] The transistor 431 includes a conductor 443 that functions as a gate electrode, an insulator 445 that functions as a gate insulator, and a portion of the substrate 701. The portion of the substrate 701 functions as a region containing the channel formation region of the transistor 431 (semiconductor region 447), a source region (either low-resistance region 449a or low-resistance region 449b), and a drain region (the other of low-resistance region 449a or low-resistance region 449b). The transistor 431 may be a p-channel transistor or an n-channel transistor.

[0101] When a single-crystal semiconductor substrate, such as a single-crystal silicon substrate, is used as the substrate 701, the transistor 431 is a transistor that contains silicon in its channel formation region (also called a "Si transistor").

[0102] Transistor 431 is electrically isolated from other transistors by the element isolation layer 403. Figure 9 shows the case where transistor 431 and other transistors are electrically isolated by the element isolation layer 403. The element isolation layer 403 can be formed using the LOCOS (LOCal Oxidation of Silicon) method or the STI (Shallow Trench Isolation) method.

[0103] Here, the transistor 431 has a convex semiconductor region 447. Furthermore, the sides and top surface of the semiconductor region 447 are covered by a conductor 443 via an insulator 445. Note that Figure 9 does not show how the conductor 443 covers the sides of the semiconductor region 447. A material that adjusts the work function can be used for the conductor 443.

[0104] A transistor with a convex semiconductor region, such as transistor 431, can be called a fin-type transistor because it utilizes the convex portion of the semiconductor substrate. It may also have an insulator in contact with the upper part of the convex portion, functioning as a mask for forming the convex portion. Furthermore, while Figure 9 shows a configuration where a portion of the substrate 701 is processed to form the convex portion, a semiconductor with a convex shape may also be formed by processing an SOI substrate.

[0105] Note that the configuration of transistor 431 shown in Figure 9 is just one example, and is not limited to this configuration. An appropriate configuration should be chosen depending on the circuit configuration or the way the circuit operates. For example, transistor 431 may be a planar transistor.

[0106] On the substrate 701, in addition to the element isolation layer 403 and the transistor 431, insulators 405, 407, 409, and 411 are provided. Conductors 451 are embedded in insulators 405, 407, 409, and 411. Here, the height of the upper surface of the conductor 451 and the height of the upper surface of the insulator 411 can be made to be approximately the same.

[0107] Insulators 421 and 422 are provided on the conductor 451 and on the insulator 411, respectively. The conductor 453 is embedded in insulators 421 and 422. Here, the height of the upper surface of the conductor 453 and the height of the upper surface of the insulator 422 can be made to be approximately the same.

[0108] An insulator 423 is provided on the conductor 453 and on the insulator 422. The conductor 455 is embedded in the insulator 423. Here, the height of the upper surface of the conductor 455 and the height of the upper surface of the insulator 423 can be made to be approximately the same.

[0109] Furthermore, if necessary, insulators and conductors may be laminated to form a multilayer wiring structure for layer 10.

[0110] [Layer 20] Layer 20 has a substrate 702 on which transistors 441 and 442 are provided. Transistor 441 is, for example, a transistor provided in a display unit driving circuit. Transistor 442 is, for example, a transistor provided in a memory unit driving circuit.

[0111] As substrate 702, a single-crystal semiconductor substrate, such as a single-crystal silicon substrate, can be used, similar to substrate 701. However, a semiconductor substrate other than a single-crystal semiconductor substrate may also be used as substrate 702. Layer 20 can have the same configuration as layer 10. Therefore, a detailed explanation of layer 20 is omitted.

[0112] In Figure 9, transistor 442 in layer 20 and transistor 431 in layer 10 are electrically connected via conductor 456. Conductor 456 functions as a TSV (Total Slip Differential). Alternatively, layer 10 and layer 20 may be electrically connected via bumps.

[0113] Layer 20 comprises a conductor 760. The conductor 760 is a conductor provided at the terminal portion. Figure 9 shows an example in which the conductor 760 is electrically connected to the FPC716 (Flexible Printed Circuit) via an anisotropic conductor 780. Various signals are supplied to the semiconductor device 100A via the FPC716.

[0114] Furthermore, the conductor 760 is electrically connected to the conductor 347 of layer 20 via conductors 353, 355, and 357. Figure 9 shows three conductors, conductors 353, 355, and 357, as conductors that electrically connect the conductor 760 and the conductor 347, but the present invention is not limited to these. There may be one, two, or four or more conductors that electrically connect the conductor 760 and the conductor 347. By providing multiple conductors that electrically connect the conductor 760 and the conductor 347, contact resistance can be reduced.

[0115] [Layer 30] Layer 30 is provided on top of layer 20. Layer 30 includes an insulator 214, and a transistor 750 is provided on the insulator 214. Transistor 750 is, for example, a transistor provided in a pixel circuit. An OS transistor can preferably be used as transistor 750. OS transistors have the characteristic of having an extremely small off-current. Therefore, the retention time of image data can be extended, and the frequency of refresh operations can be reduced. Thus, the power consumption of the semiconductor device 100A can be reduced.

[0116] Conductors 301a and 301b are embedded in insulators 254, 279, 274, and 281, respectively. Conductor 301a is electrically connected to either the source or drain of transistor 750, and conductor 301b is electrically connected to the other source or drain of transistor 750. Here, the height of the upper surfaces of conductors 301a and 301b can be made to be approximately the same as the height of the upper surface of insulator 281.

[0117] Conductors 311, 313, 331, capacitor 790, 333, and 335 are embedded in the insulator 361. Conductors 311 and 313 are electrically connected to the transistor 750 and function as wiring. Conductors 333 and 335 are electrically connected to the capacitor 790. Here, the height of the upper surfaces of conductors 331, 333, and 335 can be made to be approximately the same as the height of the upper surface of the insulator 361.

[0118] Conductors 341, 343, and 351 are embedded in the insulator 363. Here, the height of the upper surface of conductor 351 and the height of the upper surface of insulator 363 can be made to be approximately the same.

[0119] Insulators 405, 407, 409, 411, 421, 422, 423, 214, 279, 274, 281, 361, and 363 may function as interlayer films and as planarizing films that cover the uneven shapes beneath them. For example, the upper surface of insulator 363 may be planarized by a planarizing treatment using chemical mechanical polishing (CMP) to improve its flatness.

[0120] As shown in Figure 9, the capacitor 790 has a lower electrode 321 and an upper electrode 325. An insulator 323 is provided between the lower electrode 321 and the upper electrode 325. In other words, the capacitor 790 has a laminated structure in which an insulator 323, which functions as a dielectric, is sandwiched between a pair of electrodes. Although Figure 9 shows an example in which the capacitor 790 is provided on an insulator 281, the capacitor 790 may be provided on an insulator different from the insulator 281.

[0121] Figure 9 shows an example in which conductors 301a and 301b are formed in the same layer. It also shows an example in which conductors 311, 313, and the lower electrode 321 are formed in the same layer. Furthermore, it shows an example in which conductors 331, 333, and 335 are formed in the same layer. It also shows an example in which conductors 341 and 343 are formed in the same layer. In addition, it shows an example in which conductors 353, 355, and 357 are formed in the same layer. By forming multiple conductors in the same layer, the manufacturing process of the semiconductor device 100A can be simplified, thereby reducing the manufacturing cost of the semiconductor device 100A. Note that these may be formed in different layers and may be made of different types of materials.

[0122] [Layer 60] Layer 60 is provided on top of layer 30. Layer 60 includes a light-emitting element 61. The light-emitting element 61 has a conductor 772, an EL layer 786, and a conductor 788. The EL layer 786 has an organic compound or an inorganic compound of quantum dots.

[0123] Materials that can be used in organic compounds include fluorescent materials or phosphorescent materials. Materials that can be used in quantum dots include colloidal quantum dot materials, alloy-type quantum dot materials, core-shell type quantum dot materials, and core-type quantum dot materials.

[0124] The conductor 772 is electrically connected to the other side of the source or drain of the transistor 750 via conductors 351, 341, 331, 313, and 301b. The conductor 772 is formed on the insulator 363 and functions as a pixel electrode.

[0125] The conductor 772 can be made of a material that is transparent to visible light or a material that is reflective to visible light. As a transparent material, for example, an oxide material containing indium and zinc, an oxide material containing indium, gallium, and zinc (also called "IGZO"), an oxide material containing indium, zinc, and tin (also called "ITO"), or a material to which indium, zinc, tin, and silicon have been added (also called "ITSO") may be used. As a reflective material, for example, a material containing aluminum or silver may be used.

[0126] For example, if the light emitted by the light-emitting element 61 is emitted from the conductor 788 side, it is preferable that the conductor 772 contains a reflective material. The conductor 772 may have a single-layer structure or a multi-layer laminated structure. For example, when the conductor 772 is used as an anode, it may have a three-layer structure with silver sandwiched between two layers of ITO.

[0127] Furthermore, if silicon nitride is present on the surface to be formed with the conductor 772 in contact, the conductor 772 may have a three-layer structure in which aluminum, titanium oxide, and ITO (or ITSO) are stacked in that order from the surface to be formed. Alternatively, if silicon nitride is present on the surface to be formed with the conductor 772 in contact, the conductor 772 may have a two-layer structure in which aluminum and IGZO are stacked in that order from the surface to be formed.

[0128] Note that conductors 301a, 301b, 331, 351, 353, 355, 357, 453, 456, and 760 may have the same configuration as conductors 245a and 245b described in other embodiments. For example, conductor 351, which is electrically connected to the light-emitting element 61, may be a conductor containing tungsten and titanium nitride. More specifically, the side wall of the insulator 363 and tungsten may be adjacent via titanium nitride.

[0129] Although not shown in Figure 9, the semiconductor device 100A can be equipped with optical components (optical substrates) such as a polarizing member, a phase difference member, and an anti-reflective member.

[0130] In the semiconductor device 100A shown in Figure 9, an insulator 730 is provided on an insulator 363. Here, the insulator 730 can be configured to cover a portion of the conductor 772. Alternatively, by using a light-transmitting material for the conductor 788, the light-emitting element 61 can be configured as a top-emission light-emitting element that emits light towards the conductor 788. The light-emitting element 61 may also be configured as a bottom-emission element that emits light towards the conductor 772, or as a dual-emission element that emits light towards both the conductor 772 and the conductor 788. Furthermore, a structure 778 is provided between the insulator 730 and the EL layer 786.

[0131] [Sealing substrate 40] The sealing substrate 40 is provided above the layer 30, covering the display section and the layer 60. The sealing substrate 40 is bonded to the layer 30 by a sealing material 712 (also called "sealing material"). If the light-emitting element 61 is a light-emitting element with a top emission structure or a dual emission structure, a light-transmitting material is used for the sealing substrate 40.

[0132] By providing the sealing substrate 40, it is possible to prevent impurities from entering the layer 60, thereby improving the reliability of the semiconductor device 100A.

[0133] A light-shielding layer 738 is provided on the layer 60 side. The light-shielding layer 738 has the function of blocking light emitted from adjacent areas. In addition, the light-shielding layer 738 has the function of preventing ambient light from reaching the transistor 750. In Figure 9, the light-shielding layer 738 is provided so as to have an area that overlaps with the insulator 730.

[0134] Furthermore, the light-shielding layer 738 is covered with an insulator 734. The insulator 734 may be provided as needed. In this embodiment, a solid encapsulation structure is shown in which a packing layer 732 is provided between the light-emitting element 61 and the insulator 734, but a hollow encapsulation structure without a packing layer 732 may also be used. If the semiconductor device 100A is a hollow encapsulation structure, an inert gas containing a Group 18 element (noble gas) and / or nitrogen may be sealed in the area corresponding to the packing layer 732. If the light emitted from the light-emitting element 61 is emitted towards the encapsulation substrate 40, it is preferable to use a light-transmitting material as the packing layer 732.

[0135] <Example 1> Figure 10 shows a modified version of the semiconductor device 100A shown in Figure 9. The semiconductor device 100A shown in Figure 10 differs from the semiconductor device 100A shown in Figure 9 in that it has a colored layer 736. The colored layer 736 is provided so as to have an area that overlaps with the light-emitting element 61. By providing the colored layer 736, the color purity of the light extracted from the light-emitting element 61 can be increased. As a result, high-resolution images can be displayed on the semiconductor device 100A. Furthermore, since, for example, all of the light-emitting elements 61 of the semiconductor device 100A can be made into light-emitting elements that emit white light, it is not necessary to form the EL layer 786 by painting different colors, and the semiconductor device 100A can be made high-resolution.

[0136] The light-emitting element 61 can have a micro-optical resonator (microcavity) structure. Thereby, light of a predetermined color (for example, RGB) can be extracted without providing a colored layer, and the semiconductor device 100A can perform color display. By adopting a configuration in which no colored layer is provided, light absorption by the colored layer can be suppressed. As a result, the semiconductor device 100A can display a high-luminance image, and the power consumption of the semiconductor device 100A can be reduced. Note that even in the case where the EL layer 786 is formed in an island shape for each pixel or in a stripe shape for each pixel column, that is, formed by separate coating, a configuration without a colored layer can be achieved. The luminance of the semiconductor device 100A is, for example, 500 cd / m 2 or more and 20000 cd / m 2 or less, preferably 1000 cd / m 2 or more and 20000 cd / m 2 or less, more preferably 5000 cd / m 2 or more and 20000 cd / m 2 or less.

[0137] <Modification Example 2> FIG. 11 shows a cross-sectional configuration example of a semiconductor device 100B which is a modification of the semiconductor device 100A. In the cross-sectional configuration example of the semiconductor device 100B shown in FIG. 11, a conductor 348 is provided on an insulator 361 included in the layer 30 instead of the conductor 347.

[0138] The conductor 348 is electrically connected to the conductor 760 via the conductor 353, the conductor 355, and the conductor 357. The conductor 348 functions similarly to the conductor 347.

[0139] <Modification Example 3> FIG. 12 shows a cross-sectional configuration example in a structure where the layer 30 overlaps the layer 10 with the layer 20 interposed therebetween. FIG. 12 shows a cross-sectional configuration example of a semiconductor device 100C which is a modification of the semiconductor device 100B. In FIG. 12, the layer 20 is provided over the layer 10 so that a transistor included in the layer 20 and a transistor included in the layer 10 face each other. Therefore, the layer 30 is provided on the substrate 702 side included in the layer 20.

[0140] The conductor in layer 10 and the conductor in layer 20 can be electrically connected, for example, by a Cu-Cu bond. In Figure 12, for example, the conductor 455 in layer 10 and the conductor 465 in layer 20 are electrically connected by a Cu-Cu bond. In this case, the conductors 455 and 465 are formed from conductors containing Cu (copper). Furthermore, it is preferable that the insulator 423 into which the conductor 455 is embedded and the insulator 424 into which the conductor 465 is embedded are both insulators containing the same element. For example, the insulators 423 and 424 may each be silicon oxide or silicon oxynitride. By making the insulators 423 and 424 insulators containing the same element, the bonding strength between layer 10 and layer 20 is increased. Furthermore, it is preferable to perform CMP treatment on both bonding surfaces before bonding layer 10 and layer 20 to improve the flatness of both surfaces.

[0141] Furthermore, in Figure 12, the conductor of layer 10 and the conductor of layer 20 may be electrically connected via TSVs. For example, both the conductors 461 and 462 of layer 20 are TSVs that penetrate the substrate 702.

[0142] <Modification 4> Figure 13 shows an example of the cross-sectional configuration of semiconductor device 100D, which is a modified version of semiconductor device 100C. Figure 13 is a semiconductor device corresponding to the display panel 280 in Figure 4C. The example of the cross-sectional configuration shown in Figure 13 shows an example in which the transistors in layer 30 are composed of Si transistors.

[0143] Furthermore, as shown in Figure 14, a bump 454 and an adhesive layer 457 may be provided between layer 10 and layer 20. Figure 14 shows an example of a cross-sectional configuration of a semiconductor device 100G, which is a modified example of semiconductor device 100D. Figure 14 is a semiconductor device corresponding to the display panel 280 in Figure 4B. Layers 10 and 20 are fixed by an adhesive layer 457 and electrically connected by a bump 454. In Figure 14, conductors 456 and 455 are electrically connected via a bump 454. Similarly, a bump 458 and an adhesive layer 459 may be provided between layer 20 and layer 30. Layers 20 and 30 are fixed by an adhesive layer 459 and electrically connected by a bump 458. Note that the number of bumps 454 electrically connecting layer 10 and layer 20 is not limited to one, but may be multiple. The number of bumps 458 electrically connecting layer 20 and layer 30 is not limited to one, but may be multiple.

[0144] In semiconductor devices 100A, 100B, 100C, 100D, and 100G, transistors other than OS transistors (for example, Si transistors) may be used for the transistors in layer 30. Various transistors can be used for the transistors in layers 10, 20, and 30 depending on the purpose or application.

[0145] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0146] (Embodiment 4) In this embodiment, the light-emitting element 61 (also referred to as the "light-emitting device") will be described.

[0147] <Example of light-emitting element configuration> As shown in Figure 15A, the light-emitting element 61 has an EL layer 786 between a pair of electrodes (conductor 772, conductor 788). The EL layer 786 can be composed of multiple layers, such as layer 4420, light-emitting layer 4411, or layer 4430. Layer 4420 may have, for example, a layer containing a material with high electron injection properties (electron injection layer) and a layer containing a material with high electron transport properties (electron transport layer). Light-emitting layer 4411 may have, for example, a light-emitting compound. Layer 4430 may have, for example, a layer containing a material with high hole injection properties (hole injection layer) and a layer containing a material with high hole transport properties (hole transport layer).

[0148] A configuration having a layer 4420, an emissive layer 4411, and a layer 4430 provided between a pair of electrodes can function as a single emissive unit, and in this specification, the configuration shown in Figure 15A is referred to as a single structure.

[0149] Furthermore, Figure 15B shows a modified example of the EL layer 786 of the light-emitting element 61 shown in Figure 15A. Specifically, the light-emitting element 61 shown in Figure 15B has a layer 4430-1 on a conductor 772, a layer 4430-2 on layer 4430-1, a light-emitting layer 4411 on layer 4430-2, a layer 4420-1 on the light-emitting layer 4411, a layer 4420-2 on layer 4420-1, and a conductor 788 on layer 4420-2. For example, when the conductor 772 is the anode and the conductor 788 is the cathode, layer 4430-1 functions as a hole injection layer, layer 4430-2 functions as a hole transport layer, layer 4420-1 functions as an electron transport layer, and layer 4420-2 functions as an electron injection layer. Alternatively, when conductor 772 is used as the cathode and conductor 788 as the anode, layer 4430-1 functions as an electron injection layer, layer 4430-2 functions as an electron transport layer, layer 4420-1 functions as a hole transport layer, and layer 4420-2 functions as a hole injection layer. This layer structure allows for efficient injection of carriers into the light-emitting layer 4411 and improves the efficiency of carrier recombination within the light-emitting layer 4411.

[0150] As shown in Figure 15C, a configuration in which multiple light-emitting layers (light-emitting layer 4411, light-emitting layer 4412, light-emitting layer 4413) are provided between layer 4420 and layer 4430 is also an example of a single structure.

[0151] Furthermore, as shown in Figure 15D, a configuration in which multiple light-emitting units (EL layers 786a, EL layers 786b) are connected in series via an intermediate layer (charge generation layer) 4440 is referred to in this specification as a tandem structure or stacked structure. It should be noted that a tandem structure enables the realization of a light-emitting element capable of high-brightness emission.

[0152] Furthermore, if the light-emitting element 61 is in the tandem structure shown in Figure 15D, the light-emitting colors of the EL layer 786a and EL layer 786b may be the same. For example, the light-emitting colors of both the EL layer 786a and EL layer 786b may be green. Note that if the display unit includes three sub-pixels R, G, and B, and each sub-pixel has a light-emitting element, the light-emitting elements of each sub-pixel may be in a tandem structure. Specifically, the EL layer 786a and EL layer 786b of the R sub-pixel each have a material capable of emitting red light, the EL layer 786a and EL layer 786b of the G sub-pixel each have a material capable of emitting green light, and the EL layer 786a and EL layer 786b of the B sub-pixel each have a material capable of emitting blue light. In other words, the materials of the light-emitting layer 4411 and the light-emitting layer 4412 may be the same. By making the light-emitting color of EL layer 786a and EL layer 786b the same, the current density per unit of luminous intensity can be reduced. Therefore, the reliability of the light-emitting element 61 can be improved.

[0153] The light-emitting color of the light-emitting element can be red, green, blue, cyan, magenta, yellow, or white, depending on the material constituting the EL layer 786. Furthermore, the color purity can be further enhanced by adding a microcavity structure to the light-emitting element.

[0154] The light-emitting layer may contain two or more light-emitting materials that emit red (R), green (G), blue (B), yellow (Y), or orange (O). A light-emitting element that emits white light (also called a "white light-emitting device") preferably has a configuration that includes two or more types of light-emitting materials in the light-emitting layer. To obtain white light emission, one should select light-emitting materials such that the light emitted by each of the two or more materials is complementary in color. For example, by making the light-emitting color of the first light-emitting layer complementary to the light-emitting color of the second light-emitting layer, a light-emitting element that emits white light as a whole can be obtained. The same applies to light-emitting elements having three or more light-emitting layers.

[0155] The light-emitting layer preferably contains two or more light-emitting materials that emit red (R), green (G), blue (B), yellow (Y), and orange (O). Alternatively, it is preferable that the layer contains two or more light-emitting materials, and the emission of each light-emitting material contains spectral components of two or more colors from R, G, and B.

[0156] <Method for forming the light-emitting element 61> The following describes the method for forming the light-emitting element 61.

[0157] Figure 16A shows a schematic top view of the light-emitting element 61. The light-emitting element 61 has multiple red light-emitting elements 61R, multiple green light-emitting elements 61G, and multiple blue light-emitting elements 61B. In Figure 16A, the labels R, G, and B are added within the light-emitting area of ​​each light-emitting element for easy distinction. The configuration of the light-emitting element 61 shown in Figure 16A may also be called an SBS (Side By Side) structure. Furthermore, although the configuration shown in Figure 16A is an example with three colors, red (R), green (G), and blue (B), it is not limited to this. For example, a configuration with four or more colors may also be used.

[0158] The light-emitting elements 61R, 61G, and 61B are each arranged in a matrix. Figure 16A 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; delta arrangements, zigzag arrangements, or pentile arrangements may also be applied.

[0159] It is preferable to use organic EL devices such as OLED (Organic Light Emitting Diode) or QLED (Quantum-dot Light Emitting Diode) as the light-emitting elements 61R, 61G, and 61B. Examples of light-emitting materials for EL elements include fluorescent materials, phosphorescent materials, inorganic compounds (quantum dot materials), and thermally activated delayed fluorescence (TADF) materials.

[0160] Figure 16B is a schematic cross-sectional view corresponding to the dashed line A5-A6 in Figure 16A. Figure 16B shows cross-sections of the light-emitting element 61R, light-emitting element 61G, and light-emitting element 61B. The light-emitting elements 61R, 61G, and 61B are each provided on an insulating layer 251 and have a conductor 772 that functions as a pixel electrode and a conductor 788 that functions as a common electrode. The insulating layer 251 can be an inorganic insulating film or an organic insulating film, or both. It is preferable to use an inorganic insulating film as the insulating layer 251. Examples of inorganic insulating films include oxide insulating films and nitride insulating films such as silicon oxide film, silicon oxide nitride film, silicon nitride film, silicon nitride film, aluminum oxide film, aluminum oxide nitride film, or hafnium oxide film.

[0161] The light-emitting element 61R has an EL layer 786R between a conductor 772 that functions as a pixel electrode and a conductor 788 that functions as a common electrode. The EL layer 786R has a luminescent organic compound that emits light with intensity in at least the red wavelength range. The EL layer 786G of the light-emitting element 61G has a luminescent organic compound that emits light with intensity in at least the green wavelength range. The EL layer 786B of the light-emitting element 61B has a luminescent organic compound that emits light with intensity in at least the blue wavelength range.

[0162] Each of the EL layers 786R, 786G, and 786B may have, in addition to a layer containing a light-emitting organic compound (light-emitting layer), one or more of the following: an electron injection layer, an electron transport layer, a hole injection layer, and a hole transport layer.

[0163] A conductor 772, which functions as a pixel electrode, is provided for each light-emitting element. A conductor 788, which functions as a common electrode, is provided as a continuous layer common to each light-emitting element. A conductive film that is transparent to visible light is used for either the conductor 772 that functions as a pixel electrode or the conductor 788 that functions as a common electrode, and a conductive film that is reflective is used for the other. By making the conductor 772 that functions as a pixel electrode transparent and the conductor 788 that functions as a common electrode reflective, a bottom-emission type display device can be made. Conversely, by making the conductor 772 that functions as a pixel electrode reflective and the conductor 788 that functions as a common electrode transparent, a top-emission type display device can be made. Furthermore, by making both the conductor 772 that functions as a pixel electrode and the conductor 788 that functions as a common electrode transparent, a dual-emission type display device can also be made.

[0164] An insulating layer 272 is provided to cover the ends of the conductive material 772, which functions as a pixel electrode. The ends of the insulating layer 272 are preferably tapered. The insulating layer 272 can be made of the same material as that used for the insulating layer 251.

[0165] Each of the EL layers 786R, 786G, and 786B has a region that contacts the upper surface of the conductor 772, which functions as a pixel electrode, and a region that contacts the surface of the insulating layer 272. The edges of the EL layers 786R, 786G, and 786B are located on the insulating layer 272.

[0166] As shown in Figure 16B, a gap is provided between the two EL layers between light-emitting elements of different colors. It is preferable that the EL layers 786R, 786G, and 786B are arranged so that they do not touch each other. This effectively prevents current from flowing through two adjacent EL layers, which can cause unintended light emission (also known as crosstalk). Therefore, contrast can be enhanced, and a display device with high display quality can be realized.

[0167] EL layer 786R, EL layer 786G, and EL layer 786B can be differentiated by a vacuum deposition method using a shadow mask, such as a metal mask. Alternatively, they may be differentiated by photolithography. By using photolithography, it is possible to realize a display device with high resolution, which is difficult to achieve when using a metal mask.

[0168] Furthermore, a protective layer 271 is provided on the conductor 788, which functions as a common electrode, covering the light-emitting elements 61R, 61G, and 61B. The protective layer 271 has the function of preventing impurities, such as water, from diffusing to each light-emitting element from above.

[0169] The protective layer 271 can be, for example, a single-layer structure or a multilayer structure including at least an inorganic insulating film. Examples of inorganic insulating films include oxide films or nitride films represented by silicon oxide films, silicon oxide nitride films, silicon nitride films, silicon nitride films, aluminum oxide films, aluminum oxide nitride films, and hafnium oxide films. Alternatively, semiconductor materials represented by indium gallium oxide and indium gallium zinc oxide (IGZO) may be used as the protective layer 271. The protective layer 271 may be formed using ALD, CVD, and sputtering methods. Although the example shows a configuration including an inorganic insulating film as the protective layer 271, it is not limited to this. For example, the protective layer 271 may be a multilayer structure of an inorganic insulating film and an organic insulating film.

[0170] In this specification, nitride oxides refer to compounds with a higher nitrogen content than oxygen content. Oxidridides refer to compounds with a higher oxygen content than nitrogen content. The content of each element can be measured, for example, using Rutherford backscattering spectrometry (RBS).

[0171] When indium gallium zinc oxide is used as the protective layer 271, it can be processed using either a wet etching method or a dry etching method. For example, when IGZO is used as the protective layer 271, chemicals such as oxalic acid, phosphoric acid, or a mixed chemical solution (for example, a mixed chemical solution of phosphoric acid, acetic acid, nitric acid, and water (also called a mixed aluminum etchant)) can be used. The mixed aluminum etchant can be formulated in a volume ratio of approximately phosphoric acid:acetic acid:nitric acid:water = 53.3:6.7:3.3:36.7.

[0172] Figure 16C shows a different example from the one described above. Specifically, Figure 16C has a light-emitting element 61W that emits white light. The light-emitting element 61W has an EL layer 786W that emits white light between a conductor 772 that functions as a pixel electrode and a conductor 788 that functions as a common electrode.

[0173] The EL layer 786W can be configured, for example, by stacking two or more light-emitting layers selected so that their respective light-emitting colors are complementary. Alternatively, a stacked EL layer with a charge-generating layer sandwiched between the light-emitting layers may be used.

[0174] Figure 16C shows three light-emitting elements 61W arranged side by side. A colored layer 264R is provided on the top of the left light-emitting element 61W. The colored layer 264R functions as a bandpass filter that transmits red light. Similarly, a colored layer 264G that transmits green light is provided on the top of the center light-emitting element 61W, and a colored layer 264B that transmits blue light is provided on the top of the right light-emitting element 61W. As a result, the display device can display a color image.

[0175] Here, the EL layer 786W and the conductor 788, which functions as a common electrode, are separated between two adjacent light-emitting elements 61W. This prevents current from flowing through the EL layer 786W between two adjacent light-emitting elements 61W, thus preventing unintended light emission. In particular, when a stacked EL layer with a charge generation layer between two light-emitting layers is used as the EL layer 786W, the effect of crosstalk becomes more pronounced as the resolution increases, i.e., the distance between adjacent pixels decreases, resulting in a decrease in contrast. Therefore, this configuration makes it possible to realize a display device that combines high resolution and high contrast.

[0176] The separation of the EL layer 786W and the conductor 788, which functions as a common electrode, is preferably performed by photolithography. This allows for a narrower spacing between light-emitting elements, enabling the realization of a display device with a higher aperture ratio compared to, for example, a shadow mask made of a metal mask.

[0177] In the case of a bottom-emission type light-emitting element, a colored layer can be provided between the conductive element 772, which functions as a pixel electrode, and the insulating layer 251.

[0178] Figure 16D shows a different example from the above. Specifically, Figure 16D shows a configuration in which the insulating layer 272 is not provided between the light-emitting element 61R, light-emitting element 61G, and light-emitting element 61B. This configuration allows for a display device with a high aperture ratio. In addition, the protective layer 271 covers the sides of the EL layer 786R, EL layer 786G, and EL layer 786B. This configuration suppresses impurities (typically water) that could enter from the sides of the EL layer 786R, EL layer 786G, and EL layer 786B. Furthermore, in the configuration shown in Figure 16D, the top surface shapes of the conductor 772, EL layer 786R, and conductor 788 are roughly the same. Such a structure can be formed all at once using a resist mask after the conductor 772, EL layer 786R, and conductor 788 have been formed. This process, which involves using the conductor 788 as a mask to process the EL layer 786R and the conductor 788, can also be called self-aligned patterning. Although the EL layer 786R has been described here, the same configuration can be used for the EL layer 786G and the EL layer 786B.

[0179] Furthermore, in Figure 16D, a protective layer 273 is provided on top of the protective layer 271. For example, by forming the protective layer 271 using an apparatus capable of forming a highly covering film (typically an ALD apparatus) and forming the protective layer 273 using an apparatus capable of forming a film with lower covering properties than the protective layer 271 (typically a sputtering apparatus), a gap 275 can be provided between the protective layer 271 and the protective layer 273. In other words, the gap 275 is located between the EL layer 786R and the EL layer 786G, and between the EL layer 786G and the EL layer 786B.

[0180] The void 275 contains one or more of the following elements: air, nitrogen, oxygen, carbon dioxide, and Group 18 elements (typically helium, neon, argon, xenon, and krypton). The void 275 may also contain gases used during the deposition of the protective layer 273. For example, when the protective layer 273 is deposited by sputtering, the void 275 may contain one or more of the Group 18 elements mentioned above. If the void 275 contains gas, the gas can be identified by gas chromatography. Alternatively, when the protective layer 273 is deposited by sputtering, the protective layer 273 may also contain the gas used during sputtering. In this case, argon may be detected when the protective layer 273 is analyzed by energy-dispersive X-ray spectroscopy (EDX analysis).

[0181] Furthermore, if the refractive index of the air gap 275 is lower than that of the protective layer 271, the light emitted from the EL layer 786R, EL layer 786G, or EL layer 786B will be reflected at the interface between the protective layer 271 and the air gap 275. This can suppress the incidence of light emitted from the EL layer 786R, EL layer 786G, or EL layer 786B onto adjacent pixels. This can suppress the mixing of different emission colors from neighboring pixels, thereby improving the display quality of the display device.

[0182] In the configuration shown in Figure 16D, the region between the light-emitting element 61R and the light-emitting element 61G, or the region between the light-emitting element 61G and the light-emitting element 61B (hereinafter simply referred to as the distance between light-emitting elements) can be narrowed. Specifically, the distance between light-emitting elements can be 1 μm or less, preferably 500 nm or less, and more preferably 200 nm or less, 100 nm or less, 90 nm or less, 70 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 15 nm or less, or 10 nm or less. In other words, the distance between the side surface of the EL layer 786R and the side surface of the EL layer 786G, or the distance between the side surface of the EL layer 786G and the side surface of the EL layer 786B, has a region of 1 μm or less, preferably a region of 0.5 μm (500 nm) or less, and more preferably a region of 100 nm or less.

[0183] Furthermore, for example, if the air gap 275 contains gas, the configuration shown in Figure 16D can be called an air isolation structure. By having an air isolation structure, it is possible to isolate the light-emitting elements while suppressing the mixing or crosstalk of light from each light-emitting element.

[0184] The void 275 may also be filled with a filler. Examples of fillers include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. Alternatively, a photoresist may be used as a filler. The photoresist used as a filler may be a positive-type photoresist or a negative-type photoresist.

[0185] Furthermore, when filling the void 275 with a filler, it is preferable to combine an inorganic insulating material with an organic insulating material. Specifically, a laminated structure comprising aluminum oxide and a photoresist on the aluminum oxide is an example. It should be noted that the aluminum oxide is preferable when formed using the ALD method, as this enhances its coverage.

[0186] Furthermore, when comparing the aforementioned white light-emitting devices (single or tandem structure) with SBS structure light-emitting devices, SBS structure light-emitting devices can consume less power than white light-emitting devices. If you want to keep power consumption low, it is preferable to use SBS structure light-emitting devices. On the other hand, white light-emitting devices are preferable because their manufacturing process is simpler than that of SBS structure light-emitting devices, which can lead to lower manufacturing costs or higher manufacturing yields.

[0187] Figure 17A shows a different example from the one described above. Specifically, the configuration shown in Figure 17A differs from the configuration shown in Figure 16D in the configuration of the insulating layer 251. When the light-emitting elements 61R, 61G, and 61B are processed, a portion of the upper surface of the insulating layer 251 is shaved off, creating a recess. A protective layer 271 is formed in this recess. In other words, in a cross-sectional view, the lower surface of the protective layer 271 is located below the lower surface of the conductor 772. Having this region effectively suppresses impurities (typically water) that could enter the light-emitting elements 61R, 61G, and 61B from below. The recess can be formed when impurities (also called residues) that may adhere to the sides of each light-emitting element during processing are removed by wet etching. After removing the above-mentioned residues, covering the sides of each light-emitting element with the protective layer 271 makes it possible to create a highly reliable display device.

[0188] Figure 17B shows a different example from the above. Specifically, the configuration shown in Figure 17B includes an insulating layer 276 and a microlens array 277 in addition to the configuration shown in Figure 17A. The insulating layer 276 functions as an adhesive layer. When the refractive index of the insulating layer 276 is lower than that of the microlens array 277, the microlens array 277 can concentrate the light emitted from the light-emitting elements 61R, 61G, and 61B. This can improve the light extraction efficiency of the display device. This is particularly preferable when the user views the display surface of the display device from the front, as it allows for the viewing of a bright image. Various types of curing adhesives can be used as the insulating layer 276, including UV-curing photocuring adhesives, reaction-curing adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of these adhesives 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, epoxy resins with low moisture permeability are preferred. Two-component mixed resins may also be used. Adhesive sheets may also be used.

[0189] Figure 17C shows a different example from the one described above. Specifically, the configuration shown in Figure 17C has three light-emitting elements 61W instead of the light-emitting elements 61R, 61G, and 61B in the configuration shown in Figure 17A. In addition, there is an insulating layer 276 above the three light-emitting elements 61W, and above the insulating layer 276 there are colored layers 264R, 264G, and 264B. Specifically, a colored layer 264R that transmits red light is provided in the position overlapping with the left light-emitting element 61W, a colored layer 264G that transmits green light is provided in the position overlapping with the central light-emitting element 61W, and a colored layer 264B that transmits blue light is provided in the position overlapping with the right light-emitting element 61W. As a result, the semiconductor device can display a color image. The configuration shown in Figure 17C is also a modified version of the configuration shown in Figure 16C.

[0190] Figure 17D shows a different example from the one described above. Specifically, in the configuration shown in Figure 17D, the protective layer 271 is provided adjacent to the sides of the conductor 772 and the EL layer 786. The conductor 788 is provided as a continuous layer common to each light-emitting element. In addition, in the configuration shown in Figure 17D, it is preferable that the void 275 is filled with a filler material.

[0191] The color purity of the emitted light can be improved by adding a microcavity structure to the light-emitting element 61. To add a microcavity structure to the light-emitting element 61, the product of the distance d between the conductor 772 and the conductor 788 and the refractive index n of the EL layer 786 (optical distance) should be configured such that it is m times half the wavelength λ (where m is an integer greater than or equal to 1). The distance d can be calculated using Equation 1.

[0192] d = m × λ / (2 × n) ... Equation 1.

[0193] According to Equation 1, the distance d of the light-emitting element 61 in the microcavity structure is determined according to the wavelength (emission color) of the emitted light. The distance d corresponds to the thickness of the EL layer 786. Therefore, the EL layer 786G may be made thicker than the EL layer 786B, and the EL layer 786R may be made thicker than the EL layer 786G.

[0194] More precisely, distance d is the distance from the reflective region of the conductor 772, which functions as a reflective electrode, to the reflective region of the conductor 788, which functions as a semi-transparent / semi-reflective electrode. For example, if the conductor 772 is a laminate of silver and a transparent conductive film called ITO, and the ITO is on the EL layer 786 side, the distance d corresponding to the emission color can be set by adjusting the thickness of the ITO. That is, even if the thicknesses of EL layers 786R, 786G, and 786B are the same, a distance d suitable for the emission color can be obtained by changing the thickness of the ITO.

[0195] However, it can be difficult to precisely determine the location of the reflective regions in conductors 772 and 788. In this case, it is assumed that the effect of the microcavity can be sufficiently obtained by assuming that any location in conductors 772 and 788 is a reflective region.

[0196] The light-emitting element 61 is composed of a hole transport layer, another hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer. Detailed configuration examples of the light-emitting element 61 will be described in other embodiments. In order to improve the light extraction efficiency in the microcavity structure, it is preferable to make the optical distance from the conductor 772, which functions as a reflective electrode, to the light-emitting layer an odd multiple of λ / 4. To achieve this optical distance, it is preferable to appropriately adjust the thickness of each layer constituting the light-emitting element 61.

[0197] Furthermore, when light is emitted from the conductor 788 side, it is preferable that the reflectance of the conductor 788 is greater than its transmittance. Preferably, the light transmittance of the conductor 788 should be 2% to 50%, more preferably 2% to 30%, and even more preferably 2% to 10%. By reducing the transmittance (increasing the reflectance) of the conductor 788, the effect of the microcavity can be enhanced.

[0198] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0199] (Embodiment 5) This embodiment describes a transistor that can be used in a semiconductor device according to one aspect of the present invention.

[0200] <Example of transistor configuration> Figures 18A, 18B, and 18C are a top view and a cross-sectional view of a transistor 200 and its surroundings, which can be used in a semiconductor device according to one aspect of the present invention. The transistor 200 can be applied to a semiconductor device according to one aspect of the present invention. For example, it can be used as a transistor provided in layer 30.

[0201] Figure 18A is a top view of transistor 200. Figures 18B and 18C are cross-sectional views of transistor 200. Here, Figure 18B is a cross-sectional view of the area indicated by the dashed line A1-A2 in Figure 18A, and is also a cross-sectional view of transistor 200 in the channel length direction. Similarly, Figure 18C is a cross-sectional view of the area indicated by the dashed line A3-A4 in Figure 18A, and is also a cross-sectional view of transistor 200 in the channel width direction. Note that in the top view of Figure 18A, some elements have been omitted for clarity.

[0202] As shown in Figure 18, the transistor 200 includes a metal oxide 231a disposed on a substrate (not shown), a metal oxide 231b disposed on the metal oxide 231a, conductors 242a and 242b disposed on the metal oxide 231b at a distance from each other, an insulator 279 disposed on the conductors 242a and 242b with an opening formed between the conductors 242a and 242b, a conductor 260 disposed in the opening, an insulator 250 disposed between the metal oxide 231b, conductors 242a, conductors 242b, and insulator 279 and conductor 260, and a metal oxide 231c disposed between the metal oxide 231b, conductors 242a, conductors 242b, and insulator 279 and insulator 250. Here, as shown in Figures 18B and 18C, it is preferable that the upper surface of the conductor 260 substantially coincides with the upper surfaces of the insulator 250, insulator 254, metal oxide 231c, and insulator 279. In the following, metal oxide 231a, metal oxide 231b, and metal oxide 231c may be collectively referred to as metal oxide 231.

[0203] In the transistor 200 shown in Figure 18, the sides of the conductors 242a and 242b facing the conductor 260 have a generally vertical shape. However, the transistor 200 shown in Figure 18 is not limited to this, and the angle between the side and bottom surfaces of the conductors 242a and 242b may be 10° to 80°, preferably 30° to 60°. Furthermore, the opposing sides of the conductors 242a and 242b may have multiple surfaces.

[0204] As shown in Figure 18, it is preferable that an insulator 254 is placed between the insulator 224, metal oxide 231a, metal oxide 231b, conductor 242a, conductor 242b, and metal oxide 231c and the insulator 279. Here, as shown in Figures 18B and 18C, it is preferable that the insulator 254 is in contact with the side surface of the metal oxide 231c, the top and side surfaces of the conductor 242a, the top and side surfaces of the conductor 242b, the side surfaces of the metal oxide 231a and metal oxide 231b, and the top surface of the insulator 224.

[0205] In the transistor 200, a configuration is shown in which three layers of metal oxide 231a, metal oxide 231b, and metal oxide 231c are stacked in the region where the channel is formed (hereinafter also referred to as the channel formation region) and in its vicinity. However, the present invention is not limited to this. For example, a two-layer structure of metal oxide 231b and metal oxide 231c, or a stacked structure of four or more layers, may be provided. Also, in the transistor 200, the conductor 260 is shown as a two-layer stacked structure. However, the present invention is not limited to this. For example, the conductor 260 may be a single-layer structure or a stacked structure of three or more layers. Furthermore, each of the metal oxide 231a, metal oxide 231b, and metal oxide 231c may have a stacked structure of two or more layers.

[0206] For example, if the metal oxide 231c has a layered structure consisting of a first metal oxide and a second metal oxide on the first metal oxide, it is preferable that the first metal oxide has the same composition as metal oxide 231b and the second metal oxide has the same composition as metal oxide 231a.

[0207] Here, the conductor 260 functions as the gate electrode of the transistor, and the conductors 242a and 242b function as the source electrode or drain electrode, respectively. As described above, the conductor 260 is formed to be embedded in the opening of the insulator 279 and in the region sandwiched between the conductors 242a and 242b. Here, the arrangement of the conductors 260, 242a, and 242b is selected in a self-aligned manner with respect to the opening of the insulator 279. In other words, in the transistor 200, the gate electrode can be positioned in a self-aligned manner between the source electrode and the drain electrode. Therefore, since the conductor 260 can be formed without providing a positional margin, the occupied area of ​​the transistor 200 can be reduced. This makes it possible to make the display device high-resolution. It also makes it possible to make the display device narrow-bezel.

[0208] As shown in Figure 18, it is preferable that the conductor 260 has a conductor 260a provided inside the insulator 250 and a conductor 260b provided so as to be embedded inside the conductor 260a.

[0209] The transistor 200 preferably includes an insulator 214 disposed on a substrate (not shown), an insulator 216 disposed on top of the insulator 214, a conductor 205 disposed so as to be embedded in the insulator 216, an insulator 222 disposed on top of the insulator 216 and the conductor 205, and an insulator 224 disposed on top of the insulator 222. It is preferable that a metal oxide 231a is disposed on top of the insulator 224.

[0210] It is preferable that insulators 274 and 281, which function as interlayer films, are placed on top of the transistor 200. Here, it is preferable that insulator 274 is placed in contact with the upper surfaces of the conductor 260, insulator 250, insulator 254, metal oxide 231c, and insulator 279.

[0211] It is preferable that insulators 222, 254, and 274 have a function to suppress the diffusion of at least one hydrogen (e.g., hydrogen atoms, hydrogen molecules). For example, it is preferable that insulators 222, 254, and 274 have lower hydrogen permeability than insulators 224, 250, and 279. It is also preferable that insulators 222 and 254 have a function to suppress the diffusion of at least one oxygen (e.g., oxygen atoms, oxygen molecules). For example, it is preferable that insulators 222 and 254 have lower oxygen permeability than insulators 224, 250, and 279.

[0212] Here, insulator 224, metal oxide 231, and insulator 250 are separated from insulators 279 and 281 by insulators 254 and 274. Therefore, it is possible to suppress the incorporation of hydrogen impurities and excess oxygen contained in insulators 279 and 281 into insulators 224, metal oxide 231, and insulator 250.

[0213] It is preferable that conductors 245a and 245b are provided, which are electrically connected to the transistor 200 and function as plugs. In addition, insulators (insulators 241a and 241b) are provided in contact with the sides of the conductors 245a and 245b that function as plugs. That is, insulators 241a and 241b are provided in contact with the inner walls of the openings of insulators 254, 279, 274, and 281. Alternatively, a first conductor of conductors 245a and 245b may be provided in contact with the sides of insulators 241a and 241b, and a second conductor of conductors 245a and 245b may be provided further inside. Here, the height of the upper surface of conductors 245a and 245b and the height of the upper surface of insulator 281 can be made to be approximately the same. Although the transistor 200 shows a configuration in which the first conductor and the second conductor of conductors 245a and 245b are stacked, the present invention is not limited to this. For example, the conductors 245a and 245b may be provided as a single layer or as a stacked structure of three or more layers. When a structure has a stacked structure, an ordinal number may be assigned to distinguish it according to the order of formation.

[0214] In transistor 200, it is preferable to use a metal oxide that functions as an oxide semiconductor (hereinafter also referred to as an oxide semiconductor) for the metal oxide 231 (metal oxide 231a, metal oxide 231b, and metal oxide 231c) that includes the channel formation region. For example, it is preferable to use a metal oxide with a band gap of 2 eV or more, preferably 2.5 eV or more, as the metal oxide that forms the channel formation region of metal oxide 231.

[0215] The above metal oxide preferably contains at least indium (In) or zinc (Zn). In particular, it is preferable that it contains indium (In) and zinc (Zn). In addition, it is preferable that it contains element M. As element M, one or more of the following can be used: aluminum (Al), gallium (Ga), yttrium (Y), tin (Sn), boron (B), titanium (Ti), iron (Fe), nickel (Ni), germanium (Ge), zirconium (Zr), molybdenum (Mo), lanthanum (La), cerium (Ce), neodymium (Nd), hafnium (Hf), tantalum (Ta), tungsten (W), magnesium (Mg), or cobalt (Co). In particular, it is preferable that element M is one or more of aluminum (Al), gallium (Ga), yttrium (Y), or tin (Sn). Furthermore, it is even more preferable that element M contains either gallium (Ga) or tin (Sn), or both.

[0216] Furthermore, as shown in Figure 18B, the thickness of the metal oxide 231b in the region that does not overlap with the conductors 242a and 242b may be thinner than the thickness of the region that overlaps with the conductors 242a and 242b. This is formed by removing a portion of the upper surface of the metal oxide 231b when forming the conductors 242a and 242b. When a conductive film that will become the conductors 242a and 242b is deposited on the upper surface of the metal oxide 231b, a region with low resistance may be formed near the interface with the conductive film. Thus, by removing the region with low resistance located between the conductors 242a and 242b on the upper surface of the metal oxide 231b, it is possible to prevent the formation of a channel in that region.

[0217] According to one aspect of the present invention, a display device with a small size transistor and high resolution can be provided. Alternatively, a display device with a large on-current transistor and high brightness can be provided. Alternatively, a display device with a fast-operating transistor can be provided. Alternatively, a display device with a stable electrical characteristic transistor can be provided and highly reliable can be provided. Alternatively, a display device with a small off-current transistor can be provided and low power consumption can be provided.

[0218] A detailed configuration of the transistor 200, which can be used in a display device according to one aspect of the present invention, will be described.

[0219] The conductor 205 is arranged to have an overlapping region with the metal oxide 231 and the conductor 260. Furthermore, it is preferable that the conductor 205 is embedded in the insulator 216.

[0220] The conductor 205 comprises conductor 205a, conductor 205b, and conductor 205c. Conductor 205a is provided in contact with the bottom surface and side wall of an opening provided in the insulator 216. Conductor 205b is provided so as to be embedded in a recess formed in conductor 205a. Here, the upper surface of conductor 205b is lower than the upper surface of conductor 205a and the upper surface of the insulator 216. Conductor 205c is provided in contact with the upper surface of conductor 205b and the side surface of conductor 205a. Here, the height of the upper surface of conductor 205c is approximately equal to the height of the upper surface of conductor 205a and the upper surface of the insulator 216. In other words, conductor 205b is enclosed by conductors 205a and 205c.

[0221] It is preferable that the conductors 205a and 205c use conductive materials that have the function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (N2O, NO, NO2), and copper atoms. Alternatively, it is preferable to use conductive materials that have the function of suppressing the diffusion of oxygen (for example, at least one of oxygen atoms or oxygen molecules).

[0222] By using conductive materials that have the function of reducing hydrogen diffusion for conductors 205a and 205c, the diffusion of impurities, such as hydrogen contained in conductor 205b, into the metal oxide 231 via the insulator 224 can be suppressed. Furthermore, by using conductive materials that have the function of suppressing oxygen diffusion for conductors 205a and 205c, the oxidation of conductor 205b and the resulting decrease in conductivity can be suppressed. As conductive materials that have the function of suppressing oxygen diffusion, it is preferable to use, for example, titanium, titanium nitride, tantalum, tantalum nitride, ruthenium, or ruthenium oxide. Therefore, the conductive material 205a can be a single layer or a laminate of the above conductive material. For example, titanium nitride can be used for conductor 205a.

[0223] Furthermore, it is preferable to use a conductive material whose main component is tungsten, copper, or aluminum for the conductor 205b. For example, tungsten may be used for the conductor 205b.

[0224] Here, the conductor 260 may function as the first gate (also called the top gate) electrode. Also, the conductor 205 may function as the second gate (also called the bottom gate) electrode. In that case, by changing the potential applied to the conductor 205 independently of the potential applied to the conductor 260, the V of transistor 200 can be controlled. th This can be controlled. In particular, by applying a negative potential to the conductor 205, the V of transistor 200 can be controlled. th By making the voltage greater than 0V, it becomes possible to reduce the off-current. Therefore, applying a negative potential to the conductor 205 reduces the drain current when the potential applied to the conductor 260 is 0V compared to not applying a negative potential.

[0225] The conductor 205 should be larger than the channel-forming region in the metal oxide 231. In particular, as shown in Figure 18C, it is preferable that the conductor 205 extends to the region outside the end that intersects with the channel width direction of the metal oxide 231. That is, it is preferable that the conductor 205 and the conductor 260 are superimposed on the outside of the side surface in the channel width direction of the metal oxide 231, with an insulator in between.

[0226] With the above configuration, the channel-forming region of the metal oxide 231 can be electrically surrounded by the electric field of the conductor 260, which functions as the first gate electrode, and the electric field of the conductor 205, which functions as the second gate electrode.

[0227] As shown in Figure 18C, the conductor 205 is extended to function as wiring. However, the configuration is not limited to this, and a conductor that functions as wiring may be provided beneath the conductor 205.

[0228] The insulator 214 preferably functions as a barrier insulating film that suppresses the ingress of impurities, such as water or hydrogen, from the substrate side into the transistor 200. Therefore, it is preferable to use an insulating material for the insulator 214 that has the function of suppressing the diffusion of impurities, such as hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, nitrogen oxide molecules (N2O, NO, NO2), and copper atoms (the above impurities are less permeable). Alternatively, it is preferable to use an insulating material that has the function of suppressing the diffusion of at least one of oxygen (e.g., oxygen atoms, oxygen molecules) (the above oxygen is less permeable).

[0229] For example, it is preferable to use aluminum oxide or silicon nitride as the insulator 214. This suppresses the diffusion of impurities, such as water or hydrogen, from the substrate side to the transistor 200 side beyond the insulator 214. Alternatively, it suppresses the diffusion of oxygen contained in the insulator 224 towards the substrate side beyond the insulator 214.

[0230] The insulators 216, 279, and 281, which function as interlayer films, preferably have a lower dielectric constant than insulator 214. By using a material with a low dielectric constant as the interlayer film, parasitic capacitance between wirings can be reduced. For example, silicon oxide, silicon oxynitride, silicon nitride, silicon nitride, silicon oxide with added fluorine, silicon oxide with added carbon, silicon oxide with added carbon and nitrogen, or porous silicon oxide may be used as insulators 216, 279, and 281.

[0231] Insulators 222 and 224 function as gate insulators.

[0232] Here, it is preferable that the insulator 224 in contact with the metal oxide 231 desorbs oxygen upon heating. In this specification, the oxygen that is desorbed upon heating is sometimes referred to as excess oxygen. For example, silicon oxide or silicon oxide nitride may be used as the insulator 224. By providing an oxygen-containing insulator in contact with the metal oxide 231, the oxygen deficiency in the metal oxide 231 can be reduced, and the reliability of the transistor 200 can be improved.

[0233] Specifically, it is preferable to use an oxide material in which some oxygen is desorbed upon heating as the insulator 224. An oxide that desorbs oxygen upon heating is one in which the amount of oxygen desorbed, converted to oxygen atoms, is 1.0 × 10¹⁶ as determined by TDS (Thermal Desorption Spectroscopy) analysis. 18 atoms / cm 3 Preferably 1.0 × 10 19 atoms / cm 3 More preferably 2.0 × 10 19 atoms / cm 3 Above, or 3.0 × 10 20 atoms / cm 3 The oxide film is as described above. The surface temperature of the film during the TDS analysis is preferably in the range of 100°C to 700°C, or 100°C to 400°C.

[0234] As shown in Figure 18C, the thickness of the insulator 224 in the region that does not overlap with the insulator 254 and does not overlap with the metal oxide 231b may be thinner than the thickness of the other regions. In the insulator 224, it is preferable that the thickness of the region that does not overlap with the insulator 254 and does not overlap with the metal oxide 231b is such that the above-mentioned oxygen can diffuse sufficiently.

[0235] The insulator 222, like the insulator 214, preferably functions as a barrier insulating film that suppresses the ingress of impurities, such as water or hydrogen, into the transistor 200 from the substrate side. For example, it is preferable that the insulator 222 has lower hydrogen permeability than the insulator 224. By surrounding the insulator 224, the metal oxide 231, and the insulator 250 with the insulators 222, 254, and 274, it is possible to suppress the ingress of impurities, such as water or hydrogen, into the transistor 200 from the outside.

[0236] Furthermore, it is preferable that the insulator 222 has a function to suppress the diffusion of at least one of oxygen (e.g., oxygen atoms, oxygen molecules) (i.e., the above oxygen does not easily permeate). For example, it is preferable that the insulator 222 has lower oxygen permeability than the insulator 224. It is preferable that the insulator 222 has a function to suppress the diffusion of oxygen and impurities, thereby reducing the diffusion of oxygen contained in the metal oxide 231 to the substrate side. In addition, it is possible to suppress the reaction of the conductor 205 with the oxygen contained in the insulator 224 and the metal oxide 231.

[0237] The insulator 222 may be an insulator containing an oxide of one or both of the insulating materials aluminum and hafnium. Preferably, the insulator containing an oxide of one or both of aluminum and hafnium is an aluminum oxide, a hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate). When the insulator 222 is formed using such a material, the insulator 222 functions as a layer that suppresses the release of oxygen from the metal oxide 231 and the incorporation of impurities, such as hydrogen, from the periphery of the transistor 200 into the metal oxide 231.

[0238] Alternatively, aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, or zirconium oxide may be added to these insulators. Alternatively, these insulators may be subjected to nitriding treatment. Silicon oxide, silicon oxynitride, or silicon nitride may be laminated onto the above insulators.

[0239] The insulator 222 may be a single-layer or multi-layer insulator containing, for example, a so-called high-k material such as aluminum oxide, hafnium oxide, tantalum oxide, zirconium oxide, lead zirconate titanate (PZT), strontium titanate (SrTiO3), or (Ba,Sr)TiO3 (BST). As transistors become smaller and more integrated, thinning of the gate insulator can lead to leakage current problems. By using a high-k material as the insulator that functions as the gate insulator, it is possible to reduce the gate potential during transistor operation while maintaining the physical film thickness.

[0240] Furthermore, the insulators 222 and 224 may have a laminated structure of two or more layers. In that case, the laminated structure is not limited to being made of the same material, but may be made of different materials. For example, an insulator similar to the insulator 224 may be provided below the insulator 222.

[0241] The metal oxide 231 comprises metal oxide 231a, metal oxide 231b on metal oxide 231a, and metal oxide 231c on metal oxide 231b. By having metal oxide 231a below metal oxide 231b, the diffusion of impurities from structures formed below metal oxide 231a to metal oxide 231b can be suppressed. Furthermore, by having metal oxide 231c on metal oxide 231b, the diffusion of impurities from structures formed above metal oxide 231c to metal oxide 231b can be suppressed.

[0242] Furthermore, it is preferable that the metal oxide 231 has a layered structure of multiple oxide layers with different atomic ratios of each metal atom. For example, if the metal oxide 231 contains at least indium (In) and element M, it is preferable that the ratio of the number of atoms of element M contained in metal oxide 231a to the total number of atoms of all elements constituting metal oxide 231a is higher than the ratio of the number of atoms of element M contained in metal oxide 231b to the total number of atoms of all elements constituting metal oxide 231b. It is also preferable that the atomic ratio of element M contained in metal oxide 231a to In is higher than the atomic ratio of element M contained in metal oxide 231b to In. Here, metal oxide 231c can be any metal oxide that can be used in metal oxide 231a or metal oxide 231b.

[0243] It is preferable that the energy at the lower end of the conduction band of metal oxide 231a and metal oxide 231c is higher than the energy at the lower end of the conduction band of metal oxide 231b. In other words, it is preferable that the electron affinity of metal oxide 231a and metal oxide 231c is smaller than the electron affinity of metal oxide 231b. In this case, it is preferable that metal oxide 231c is a metal oxide that can be used for metal oxide 231a. Specifically, it is preferable that the ratio of the number of atoms of element M contained in metal oxide 231c to the total number of atoms of all elements constituting metal oxide 231c is higher than the ratio of the number of atoms of element M contained in metal oxide 231b to the total number of atoms of all elements constituting metal oxide 231b. It is also preferable that the atomic ratio of element M contained in metal oxide 231c to In is higher than the atomic ratio of element M contained in metal oxide 231b to In.

[0244] Here, at the junctions of metal oxide 231a, metal oxide 231b, and metal oxide 231c, the energy levels at the lower end of the conduction band change smoothly. In other words, the energy levels at the lower end of the conduction band at the junctions of metal oxide 231a, metal oxide 231b, and metal oxide 231c can be said to change continuously or be continuously joined. To achieve this, it is desirable to lower the defect level density of the mixed layer formed at the interface between metal oxide 231a and metal oxide 231b, and at the interface between metal oxide 231b and metal oxide 231c.

[0245] Specifically, by having metal oxides 231a and 231b, and metal oxides 231b and 231c, share a common element other than oxygen (which serves as the main component), a mixed layer with a low defect level density can be formed. For example, if metal oxide 231b is In-Ga-Zn oxide, then In-Ga-Zn oxide, Ga-Zn oxide, and gallium oxide may be used as metal oxides 231a and 231c. Furthermore, metal oxide 231c may be in a layered structure. For example, a layered structure of In-Ga-Zn oxide and Ga-Zn oxide on the In-Ga-Zn oxide, or a layered structure of In-Ga-Zn oxide and gallium oxide on the In-Ga-Zn oxide can be used. In other words, a layered structure of In-Ga-Zn oxide and an oxide that does not contain In may be used as metal oxide 231c.

[0246] Specifically, for metal oxide 231a, a metal oxide with an atomic ratio of In:Ga:Zn = 1:3:4 or 1:1:0.5 may be used. For metal oxide 231b, a metal oxide with an atomic ratio of In:Ga:Zn = 4:2:3 or 3:1:2 may be used. For metal oxide 231c, a metal oxide with an atomic ratio of In:Ga:Zn = 1:3:4, In:Ga:Zn = 4:2:3, Ga:Zn = 2:1, or Ga:Zn = 2:5 may be used. Furthermore, specific examples of layered structures for metal oxide 231c include a layered structure of In:Ga:Zn=4:2:3 [atomic ratio] and Ga:Zn=2:1 [atomic ratio], a layered structure of In:Ga:Zn=4:2:3 [atomic ratio] and Ga:Zn=2:5 [atomic ratio], and a layered structure of In:Ga:Zn=4:2:3 [atomic ratio] and gallium oxide.

[0247] In this case, the main carrier pathway is through metal oxide 231b. By configuring metal oxide 231a and metal oxide 231c as described above, the defect level density at the interface between metal oxide 231a and metal oxide 231b, and at the interface between metal oxide 231b and metal oxide 231c, can be reduced. As a result, the influence of interface scattering on carrier conduction is reduced, and transistor 200 can obtain high on-current and high frequency characteristics. Furthermore, if metal oxide 231c is in a multilayer structure, in addition to the effect of reducing the defect level density at the interface between metal oxide 231b and metal oxide 231c as described above, it is expected that the diffusion of constituent elements of metal oxide 231c towards the insulator 250 will be suppressed. More specifically, by making metal oxide 231c in a multilayer structure and positioning an oxide that does not contain In on top of the multilayer structure, it is possible to suppress In that could diffuse towards the insulator 250. Since the insulator 250 functions as a gate insulator, if In diffuses, it will result in poor transistor characteristics. Therefore, by using a layered structure for the metal oxide 231c, it becomes possible to provide a highly reliable display device.

[0248] Conductors 242a and 242b, which function as source electrodes and drain electrodes, are provided on the metal oxide 231b. It is preferable to use metal elements selected from aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, tungsten, hafnium, vanadium, niobium, manganese, magnesium, zirconium, beryllium, indium, ruthenium, iridium, strontium, and lanthanum, or alloys composed of the above metal elements, or alloys combining the above metal elements, as conductors 242a and 242b. For example, it is preferable to use tantalum nitride, titanium nitride, tungsten, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, or oxides containing lanthanum and nickel. Furthermore, tantalum nitride, titanium nitride, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, and oxides containing lanthanum and nickel are preferred because they are conductive materials that are resistant to oxidation or maintain conductivity even when absorbing oxygen.

[0249] By providing the conductors 242a and 242b in contact with the metal oxide 231, the oxygen concentration in the vicinity of the conductors 242a and 242b of the metal oxide 231 may be reduced. In addition, a metal compound layer containing the metal contained in the conductors 242a and 242b and the components of the metal oxide 231 may be formed in the vicinity of the conductors 242a and 242b of the metal oxide 231. In such a case, the carrier concentration increases in the region near the conductors 242a and 242b of the metal oxide 231, and this region becomes a low-resistance region.

[0250] Here, the region between the conductor 242a and the conductor 242b is formed by superimposing it on the opening of the insulator 279. This allows the conductor 260 to be positioned self-aligned between the conductor 242a and the conductor 242b.

[0251] The insulator 250 functions as a gate insulator. It is preferable that the insulator 250 be placed in contact with the upper surface of the metal oxide 231c. The insulator 250 can be silicon oxide, silicon oxynitride, silicon nitride, silicon nitride, fluorine-added silicon oxide, carbon-added silicon oxide, carbon and nitrogen-added silicon oxide, or porous silicon oxide. Silicon oxide and silicon oxynitride are particularly preferred because they are thermally stable.

[0252] Similar to the insulator 224, it is preferable that the insulator 250 has a reduced concentration of impurities, such as water or hydrogen. The film thickness of the insulator 250 is preferably between 1 nm and 20 nm.

[0253] A metal oxide may be provided between the insulator 250 and the conductor 260. It is preferable that the metal oxide suppresses oxygen diffusion from the insulator 250 to the conductor 260. This suppresses the oxidation of the conductor 260 by oxygen from the insulator 250.

[0254] The metal oxide may function as part of the gate insulator. Therefore, when silicon oxide or silicon oxynitride is used for the insulator 250, it is preferable to use a metal oxide that is a high-k material with a high dielectric constant. By making the gate insulator a laminated structure of insulator 250 and the metal oxide, a laminated structure that is stable against heat and has a high dielectric constant can be made. Therefore, it becomes possible to reduce the gate potential applied during transistor operation while maintaining the physical film thickness of the gate insulator. In addition, it becomes possible to thin the equivalent oxide film thickness (EOT) of the insulator that functions as a gate insulator.

[0255] Specifically, a metal oxide containing one or more selected from hafnium, aluminum, gallium, yttrium, zirconium, tungsten, titanium, tantalum, nickel, germanium, or magnesium can be used. In particular, it is preferable to use aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate), which are insulators containing an oxide of one or both of aluminum and hafnium.

[0256] Although the conductor 260 is shown as a two-layer structure in FIG. 18, it may be a single-layer structure or a stacked structure of three or more layers.

[0257] As the conductor 260a, it is preferable to use a conductor having a function of suppressing diffusion of the aforementioned impurities typified by hydrogen atoms, hydrogen molecules, water molecules, nitrogen atoms, nitrogen molecules, and nitrogen oxide molecules (N₂O, NO, NO₂), and copper atoms. Alternatively, it is preferable to use a conductive material having a function of suppressing diffusion of oxygen (oxygen atoms or oxygen molecules).

[0258] Since the conductor 260a has a function of suppressing diffusion of oxygen, it is possible to suppress a decrease in conductivity caused by oxidation of the conductor 260b due to oxygen contained in the insulator 250. As the conductive material having a function of suppressing diffusion of oxygen, for example, tantalum, tantalum nitride, ruthenium, or ruthenium oxide is preferably used.

[0259] As the conductor 260b, a conductive material containing tungsten, copper, or aluminum as a main component is preferably used. In addition, since the conductor 260 also functions as a wiring, it is preferable to use a conductor with high conductivity. For example, a conductive material containing tungsten, copper, or aluminum as a main component can be used. Further, the conductor 260b may have a stacked structure, for example, a stacked structure of titanium or titanium nitride and the above conductive material may be employed.

[0260] As shown in Figures 18A and 18C, in the region of the metal oxide 231b that does not overlap with the conductors 242a and 242b, in other words, in the channel-forming region of the metal oxide 231, the side surface of the metal oxide 231 is covered by the conductor 260. This makes it easier to apply the electric field of the conductor 260, which functions as the first gate electrode, to the side surface of the metal oxide 231. Therefore, the on-current of the transistor 200 can be increased and the frequency characteristics can be improved.

[0261] The insulator 254, like the insulator 214, preferably functions as a barrier insulating film that suppresses the ingress of impurities, such as water or hydrogen, into the transistor 200 from the insulator 279 side. For example, it is preferable that the insulator 254 has lower hydrogen permeability than the insulator 224. Furthermore, as shown in Figures 18B and 18C, it is preferable that the insulator 254 is in contact with the side surface of the metal oxide 231c, the top and side surfaces of the conductor 242a, the top and side surfaces of the conductor 242b, the side surfaces of the metal oxide 231a and metal oxide 231b, and the top surface of the insulator 224. With this configuration, it is possible to suppress the ingress of hydrogen contained in the insulator 279 into the metal oxide 231 from the top or side surfaces of the conductor 242a, conductor 242b, metal oxide 231a, metal oxide 231b, and the insulator 224.

[0262] Furthermore, it is preferable that the insulator 254 has the function of suppressing the diffusion of oxygen (oxygen atoms or oxygen molecules) (i.e., it is difficult for the above-mentioned oxygen to permeate it). For example, it is preferable that the insulator 254 has lower oxygen permeability than the insulator 279 or the insulator 224.

[0263] The insulator 254 is preferably deposited using a sputtering method. By depositing the insulator 254 using a sputtering method in an oxygen-containing atmosphere, oxygen can be added to the vicinity of the region of the insulator 224 that is in contact with the insulator 254. This allows oxygen to be supplied from this region to the metal oxide 231 via the insulator 224. Here, the insulator 254 has a function to suppress upward diffusion of oxygen, thereby preventing oxygen from diffusing from the metal oxide 231 to the insulator 279. In addition, the insulator 222 has a function to suppress downward diffusion of oxygen, thereby preventing oxygen from diffusing from the metal oxide 231 to the substrate side. In this way, oxygen is supplied to the channel formation region of the metal oxide 231. This reduces oxygen deficiency in the metal oxide 231 and suppresses normally-on formation of the transistor.

[0264] As the insulator 254, for example, an insulator containing an oxide of one or both of aluminum and hafnium may be formed as a film. It is preferable to use aluminum oxide, hafnium oxide, or an oxide containing aluminum and hafnium (hafnium aluminate) as the insulator containing an oxide of one or both of aluminum and hafnium.

[0265] The insulator 224, insulator 250, and metal oxide 231 are covered by the hydrogen barrier insulator 254, so the insulator 279 is separated from the insulator 224, metal oxide 231, and insulator 250 by the insulator 254. This prevents impurities, such as hydrogen, from entering the transistor 200 from the outside, thus providing the transistor 200 with good electrical characteristics and reliability.

[0266] The insulator 279 is provided on the insulator 224, metal oxide 231, conductor 242a, and conductor 242b via the insulator 254. For example, the insulator 279 is preferably silicon oxide, silicon oxynitride, silicon nitride, fluorine-added silicon oxide, carbon-added silicon oxide, carbon and nitrogen-added silicon oxide, or porous silicon oxide. Silicon oxide and silicon oxynitride are particularly preferred because they are thermally stable. Silicon oxide, silicon oxynitride, and porous silicon oxide are particularly preferred because they can easily form regions containing oxygen that is desorbed by heating.

[0267] It is preferable that the concentration of impurities, such as water or hydrogen, in the insulator 279 is reduced. Furthermore, the upper surface of the insulator 279 may be flattened.

[0268] The insulator 274, like the insulator 214, preferably functions as a barrier insulating film that suppresses the incorporation of impurities, such as water or hydrogen, into the insulator 279 from above. For example, the insulator 274 can be an insulator that can be used for insulators 214 and 254.

[0269] It is preferable to provide an insulator 281, which functions as an interlayer film, on top of the insulator 274. Similar to the insulator 224, it is preferable that the insulator 281 has a reduced concentration of impurities, such as water or hydrogen, in the film.

[0270] Conductors 245a and 245b are placed in the openings formed in insulators 281, 274, 279, and 254. Conductors 245a and 245b are provided facing each other with conductor 260 in between. The height of the upper surfaces of conductors 245a and 245b may be on the same plane as the upper surface of insulator 281.

[0271] Furthermore, an insulator 241a is provided in contact with the inner wall of the opening of insulators 281, 274, 279, and 254, and a first conductive portion of conductor 245a is formed in contact with its side surface. Conductor 242a is located in at least a portion of the bottom of the opening, and conductor 245a is in contact with conductor 242a. Similarly, an insulator 241b is provided in contact with the inner wall of the opening of insulators 281, 274, 279, and 254, and a first conductive portion of conductor 245b is formed in contact with its side surface. Conductor 242b is located in at least a portion of the bottom of the opening, and conductor 245b is in contact with conductor 242b.

[0272] It is preferable that the conductors 245a and 245b be made of conductive materials mainly composed of tungsten, copper, or aluminum. Furthermore, the conductors 245a and 245b may be arranged in a laminated structure.

[0273] When conductors 242a and 242b are arranged in a laminated structure, it is preferable to use a conductor that has the function of suppressing the diffusion of impurities, such as water or hydrogen, as described above, for the conductors that come into contact with metal oxide 231a, metal oxide 231b, conductor 242a, conductor 242b, insulator 254, insulator 279, insulator 274, and insulator 281. For example, it is preferable to use tantalum, tantalum nitride, titanium, titanium nitride, ruthenium, or ruthenium oxide. Furthermore, the conductive material that has the function of suppressing the diffusion of impurities, such as water or hydrogen, may be used in a single layer or a laminate. By using such a conductive material, it is possible to suppress the absorption of oxygen added to insulator 279 by conductors 245a and 245b. In addition, it is possible to suppress the mixing of impurities, such as water or hydrogen, from the layer above insulator 281 into metal oxide 231 through conductors 245a and 245b.

[0274] For insulators 241a and 241b, for example, an insulator that can be used for insulator 254 may be used. Since insulators 241a and 241b are provided in contact with insulator 254, it is possible to suppress the mixing of impurities, such as water or hydrogen, from insulator 279 into metal oxide 231 through conductors 245a and 245b. Furthermore, it is possible to suppress the absorption of oxygen contained in insulator 279 into conductors 245a and 245b.

[0275] Although not shown in the figures, conductors that function as wiring may be placed in contact with the upper surfaces of conductor 245a and conductor 245b. The conductors that function as wiring are preferably made of a conductive material mainly composed of tungsten, copper, or aluminum. The conductors may also be in a laminated structure, for example, a laminate of titanium or titanium nitride and the conductive material. The conductors may be formed to be embedded in openings provided in the insulator.

[0276] <Materials that make up a transistor> This section describes the constituent materials that can be used in transistors.

[0277] [substrate] As a substrate for forming the transistor 200, for example, an insulator substrate, a semiconductor substrate, or a conductor substrate may be used. Examples of the insulator substrate include a glass substrate, a quartz substrate, a sapphire substrate, a stabilized zirconia substrate (an yttria-stabilized zirconia substrate), and a resin substrate. Examples of the semiconductor substrate include a semiconductor substrate of silicon or germanium, or a compound semiconductor substrate composed of silicon carbide, silicon germanium, gallium arsenide, indium phosphide, zinc oxide, or gallium oxide. Further, there is a semiconductor substrate having an insulator region inside the aforementioned semiconductor substrate, for example, an SOI (Silicon On Insulator) substrate. Examples of the conductor substrate include a graphite substrate, a metal substrate, an alloy substrate, and a conductive resin substrate. Alternatively, there are a substrate containing a metal nitride and a substrate containing a metal oxide. Further, there are a substrate in which a conductor or a semiconductor is provided on an insulator substrate, a substrate in which a conductor or an insulator is provided on a semiconductor substrate, and a substrate in which a semiconductor or an insulator is provided on a conductor substrate. Alternatively, a substrate in which an element is provided on these substrates may be used. Examples of the element provided on the substrate include a capacitive element, a resistive element, a switch element, a light-emitting element, and a memory element.

[0278] [Insulator] As the insulator, there are an insulating oxide, nitride, oxynitride, nitride oxide, metal oxide, metal oxynitride, and metal nitride oxide each having insulating properties.

[0279] For example, as miniaturization and higher integration of transistors progress, thinning of the gate insulator may cause a problem of leakage current. By using a high-k material for the insulator functioning as the gate insulator, it is possible to lower the operating voltage of the transistor while maintaining the physical film thickness. On the other hand, by using a material with a low relative permittivity for the insulator functioning as an interlayer film, parasitic capacitance generated between wirings can be reduced. Therefore, the material is preferably selected in accordance with the function of the insulator.

[0280] Examples of insulators with high dielectric constants include gallium oxide, hafnium oxide, zirconium oxide, oxides containing aluminum and hafnium, oxides containing aluminum and hafnium, oxides containing silicon and hafnium, oxides containing silicon and hafnium, or nitrides containing silicon and hafnium.

[0281] Examples of insulators with low dielectric constant include silicon oxide, silicon oxide nitride, silicon oxide nitride, silicon nitride, fluorine-added silicon oxide, carbon-added silicon oxide, carbon and nitrogen-added silicon oxide, porous silicon oxide, or resins.

[0282] Transistors using oxide semiconductors can have their electrical properties stabilized by surrounding them with an insulator (insulator 214, insulator 222, insulator 254, and insulator 274) that has the function of suppressing the permeation of impurities such as hydrogen and oxygen. As an insulator that has the function of suppressing the permeation of impurities such as hydrogen and oxygen, for example, an insulator containing boron, carbon, nitrogen, oxygen, fluorine, magnesium, aluminum, silicon, phosphorus, chlorine, argon, gallium, germanium, yttrium, zirconium, lanthanum, neodymium, hafnium, or tantalum can be used in a single layer or in a multilayer structure. Specifically, as an insulator that has the function of suppressing the permeation of impurities such as hydrogen and oxygen, metal oxides such as aluminum oxide, magnesium oxide, gallium oxide, germanium oxide, yttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide, hafnium oxide, or tantalum oxide, metal nitrides such as aluminum nitride, titanium aluminum nitride, titanium nitride, silicon oxide nitride, or silicon nitride can be used.

[0283] The insulator that functions as a gate insulator is preferably an insulator that has a region containing oxygen that is released by heating. For example, by having a structure in which silicon oxide or silicon oxynitride having a region containing oxygen that is released by heating is in contact with the metal oxide 231, the oxygen deficiency of the metal oxide 231 can be compensated for.

[0284] [conductor] As a conductor, it is preferable to use a metallic element selected from aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, tungsten, hafnium, vanadium, niobium, manganese, magnesium, zirconium, beryllium, indium, ruthenium, iridium, strontium, and lanthanum, or an alloy containing the above metallic elements, or an alloy combining the above metallic elements. For example, it is preferable to use tantalum nitride, titanium nitride, tungsten, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, or oxides containing lanthanum and nickel. Furthermore, tantalum nitride, titanium nitride, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, and oxides containing lanthanum and nickel are preferred because they are conductive materials that are resistant to oxidation or maintain conductivity even when absorbing oxygen. Alternatively, semiconductors with high electrical conductivity, such as polycrystalline silicon containing impurity elements like phosphorus, or nickel silicide may be used.

[0285] Multiple conductors formed from the above materials may be used in a laminated structure. For example, a laminated structure may be formed by combining a material containing the aforementioned metal element with a conductive material containing oxygen. Alternatively, a laminated structure may be formed by combining a material containing the aforementioned metal element with a conductive material containing nitrogen. Furthermore, a laminated structure may be formed by combining a material containing the aforementioned metal element with a conductive material containing oxygen and a conductive material containing nitrogen.

[0286] Furthermore, when using a metal oxide for the channel formation region of a transistor, it is preferable to use a laminated structure for the conductor functioning as the gate electrode, which combines a material containing the aforementioned metal element with a conductive material containing oxygen. In this case, it is preferable to place the conductive material containing oxygen on the channel formation region side. By placing the conductive material containing oxygen on the channel formation region side, oxygen released from the conductive material is more easily supplied to the channel formation region.

[0287] In particular, it is preferable to use a conductive material containing the metal element and oxygen contained in the metal oxide in which the channel is formed as the conductor that functions as the gate electrode. Alternatively, conductive materials containing the aforementioned metal element and nitrogen may be used. For example, conductive materials containing nitrogen such as titanium nitride and tantalum nitride may be used. Alternatively, indium tin oxide, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide, and silicon-doped indium tin oxide may be used. In addition, indium gallium zinc oxide containing nitrogen may be used. By using such materials, it may be possible to capture hydrogen contained in the metal oxide in which the channel is formed. Alternatively, it may be possible to capture hydrogen introduced from the outer insulator.

[0288] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0289] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0290] (Embodiment 6) This embodiment describes metal oxides (hereinafter also referred to as oxide semiconductors) that can be used in the OS transistor described in the above embodiment.

[0291] <Classification of crystal structures> First, we will explain the classification of crystal structures in oxide semiconductors using Figure 19A. Figure 19A is a diagram illustrating the classification of crystal structures in oxide semiconductors, specifically IGZO (a metal oxide containing In, Ga, and Zn).

[0292] As shown in Figure 19A, oxide semiconductors are broadly classified into "Amorphous," "Crystalline," and "Crystal." "Amorphous" includes completely amorphous materials. "Crystalline" includes CAAC (c-axis-aligned crystalline), nc (nanocrystalline), and CAC (cloud-aligned composite) (excluding single crystal and polycrystal). Note that single crystal, polycrystal, and completely amorphous materials are excluded from the "Crystalline" classification. "Crystal" includes single crystal and polycrystal materials.

[0293] The structure within the thick frame shown in Figure 19A represents an intermediate state between "Amorphous" and "Crystal," and belongs to a new boundary region (New crystalline phase). In other words, this structure can be described as being completely different from "Crystal" or the energetically unstable "Amorphous."

[0294] The crystal structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectroscopy. Figure 19B shows the XRD spectrum obtained by GIXD (Grazing-Incidence XRD) measurement of a CAAC-IGZO film classified as "Crystalline." The GIXD method is also known as the thin-film method or Seemann-Bohlin method. Hereafter, the XRD spectrum obtained by the GIXD measurement shown in Figure 19B will simply be referred to as the XRD spectrum. In Figure 19B, the vertical axis represents intensity, and the horizontal axis represents 2θ. The composition of the CAAC-IGZO film shown in Figure 19B is approximately In:Ga:Zn = 4:2:3 [atomic ratio]. The thickness of the CAAC-IGZO film shown in Figure 19B is 500 nm.

[0295] As shown in Figure 19B, the XRD spectrum of the CAAC-IGZO film shows a peak indicating clear crystallinity. Specifically, the XRD spectrum of the CAAC-IGZO film shows a peak indicating c-axis orientation near 2θ=31°. As shown in Figure 19B, the peak near 2θ=31° is asymmetrical with respect to the angle at which the peak intensity was detected.

[0296] The crystal structure of a film or substrate can be evaluated by the diffraction pattern (also called the nano-beam electron diffraction pattern) observed by nano-beam electron diffraction (NBED). The diffraction pattern of a CAAC-IGZO film is shown in Figure 19C. Figure 19C shows the diffraction pattern observed by NBED with the electron beam incident parallel to the substrate. The composition of the CAAC-IGZO film shown in Figure 19C is approximately In:Ga:Zn = 4:2:3 [atomic ratio]. Furthermore, in nano-beam electron diffraction, electron diffraction is performed with a probe diameter of 1 nm.

[0297] As shown in Figure 19C, the diffraction pattern of the CAAC-IGZO film shows multiple spots indicating c-axis orientation.

[0298] [Structure of oxide semiconductors] Note that when focusing on the crystal structure, oxide semiconductors may be classified differently from those shown in Figure 19A. For example, oxide semiconductors can be divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the aforementioned CAAC-OS and nc-OS. Furthermore, non-single-crystal oxide semiconductors include polycrystalline oxide semiconductors, pseudo-amorphous oxide semiconductors (a-like OS: amorphous-like oxide semiconductors), and amorphous oxide semiconductors.

[0299] Here, we will explain the details of the CAAC-OS, nc-OS, and a-like OS mentioned above.

[0300] [CAAC-OS] CAAC-OS is an oxide semiconductor having multiple crystalline regions, the c-axis of which is oriented in a specific direction. This specific direction is the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region with periodic atomic arrangement. If we consider the atomic arrangement as a lattice arrangement, then a crystalline region is also a region with a aligned lattice arrangement. Furthermore, CAAC-OS has regions where multiple crystalline regions are connected in the ab-plane direction, and these regions may exhibit distortion. Distortion refers to a point in the connected region where the orientation of the lattice arrangement changes between a region with a aligned lattice arrangement and another region with a aligned lattice arrangement. In short, CAAC-OS is an oxide semiconductor that is c-axis oriented and does not exhibit clear orientation in the ab-plane direction.

[0301] Each of the multiple crystalline regions described above is composed of one or more minute crystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of a single minute crystal, the maximum diameter of that crystalline region is less than 10 nm. When a crystalline region is composed of many minute crystals, the size of that crystalline region may be around several tens of nanometers.

[0302] In In-M-Zn oxide (where element M is one or more elements selected from aluminum, gallium, yttrium, tin, and titanium), CAAC-OS tends to have a layered crystalline structure (also called a layered structure) consisting of layers containing indium (In) and oxygen (hereinafter referred to as the In layer) and layers containing element M, zinc (Zn), and oxygen (hereinafter referred to as the (M,Zn) layer). Indium and element M are mutually substitutable. Therefore, the (M,Zn) layer may contain indium. The In layer may also contain element M. The In layer may also contain Zn. This layered structure can be observed, for example, as a lattice image in high-resolution TEM images.

[0303] When structural analysis of a CAAC-OS film is performed using an XRD instrument, for example, out-of-plane XRD measurements using θ / 2θ scanning show a peak indicating c-axis orientation at 2θ = 31° or nearby. Note that the position of the c-axis orientation peak (value of 2θ) may vary depending on the type of metal element and composition constituting the CAAC-OS.

[0304] For example, multiple bright spots are observed in the electron diffraction pattern of a CAAC-OS film. These spots are observed at point-symmetric positions with respect to the incident electron beam spot (also called the direct spot) that passed through the sample.

[0305] When the crystal region is observed from the specific direction described above, the lattice arrangement within that crystal region is based on a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be non-regular hexagonal. Furthermore, the strain may have a pentagonal or heptagonal lattice arrangement. Moreover, in CAAC-OS, clear grain boundaries cannot be observed even near the strain. In other words, it can be seen that the formation of grain boundaries is suppressed by the strain in the lattice arrangement. This is thought to be because CAAC-OS can tolerate strain due to the non-dense arrangement of oxygen atoms in the ab-plane direction and the change in interatomic bond distances due to the substitution of metal atoms.

[0306] A crystal structure in which clear grain boundaries are observed is called a polycrystal. Grain boundaries act as recombination centers, trapping carriers and potentially causing a decrease in the transistor's on-current or field-effect mobility. Therefore, CAAC-OS, which does not exhibit clear grain boundaries, is one of the crystalline oxides with a suitable crystal structure for the semiconductor layer of a transistor. In addition, a structure containing Zn is preferred for the composition of CAAC-OS. For example, In-Zn oxide and In-Ga-Zn oxide are preferred because they suppress the generation of grain boundaries more effectively than In oxide.

[0307] CAAC-OS is an oxide semiconductor with high crystallinity and no clearly defined grain boundaries. Therefore, CAAC-OS is less susceptible to the decrease in electron mobility caused by grain boundaries. Furthermore, since the crystallinity of oxide semiconductors can decrease due to the inclusion of impurities and / or the generation of defects, CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (oxygen vacancies). Consequently, oxide semiconductors containing CAAC-OS have stable physical properties. Therefore, oxide semiconductors containing CAAC-OS are heat-resistant and highly reliable. In addition, CAAC-OS is stable even at high temperatures (so-called thermal budget) during the manufacturing process. Therefore, using CAAC-OS in OS transistors allows for greater flexibility in the manufacturing process.

[0308] [nc-OS] nc-OS exhibits periodicity in atomic arrangement in minute regions (e.g., regions between 1 nm and 10 nm, particularly between 1 nm and 3 nm). In other words, nc-OS contains minute crystals. These minute crystals are also called nanocrystals because their size is, for example, between 1 nm and 10 nm, particularly between 1 nm and 3 nm. Furthermore, nc-OS shows no regularity in crystal orientation between different nanocrystals. Therefore, no orientation is observed throughout the film. Consequently, depending on the analytical method, nc-OS may be indistinguishable from a-like OS and amorphous oxide semiconductors. For example, when structural analysis of an nc-OS film is performed using an XRD instrument, no peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Also, when electron diffraction (also called limited-field electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter larger than that of the nanocrystals (e.g., 50 nm or larger), a diffraction pattern resembling a halo pattern is observed. On the other hand, when electron diffraction (also called nanobeam electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter close to or smaller than the size of the nanocrystal (for example, 1 nm to 30 nm), an electron diffraction pattern may be obtained in which multiple spots are observed within a ring-shaped region centered on a direct spot.

[0309] [a-like OS] a-like OS is an oxide semiconductor having a structure between nc-OS and amorphous oxide semiconductors. a-like OS has porous or low-density regions. That is, a-like OS has lower crystallinity compared to nc-OS and CAAC-OS. Also, a-like OS has a higher hydrogen concentration in the film compared to nc-OS and CAAC-OS.

[0310] [Oxide semiconductor configuration] Next, we will explain the details of CAC-OS mentioned above. Note that CAC-OS refers to the material composition.

[0311] [CAC-OS] CAC-OS is a material composition in which, for example, the elements constituting the metal oxide are unevenly distributed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size. In the following, a state in which one or more metal elements are unevenly distributed in a metal oxide, and the regions containing these metal elements are mixed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size, is also referred to as a mosaic or patchy state.

[0312] Furthermore, CAC-OS is a composite metal oxide having a mosaic-like structure formed by the separation of the material into a first region and a second region, with the first region distributed within the film (hereinafter also referred to as a cloud-like structure). In other words, CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed.

[0313] Here, the atomic ratios of In, Ga, and Zn to the metal elements constituting the CAC-OS in In-Ga-Zn oxide are denoted as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS of In-Ga-Zn oxide, the first region is the region where [In] is greater than the [In] in the composition of the CAC-OS film. The second region is the region where [Ga] is greater than the [Ga] in the composition of the CAC-OS film. Alternatively, for example, the first region is the region where [In] is greater than the [In] in the second region, and [Ga] is smaller than the [Ga] in the second region. The second region is the region where [Ga] is greater than the [Ga] in the first region, and [In] is smaller than the [In] in the first region.

[0314] Specifically, the first region described above is a region whose main components are indium oxide and indium zinc oxide. The second region described above is a region whose main components are gallium oxide and gallium zinc oxide. In other words, the first region can be rephrased as a region whose main component is In. The second region can be rephrased as a region whose main component is Ga.

[0315] Furthermore, a clear boundary may not be observed between the first region and the second region described above.

[0316] For example, in the case of CAC-OS in In-Ga-Zn oxide, EDX mapping obtained using energy dispersive X-ray spectroscopy (EDX) confirms that it has a structure in which regions mainly composed of In (first region) and regions mainly composed of Ga (second region) are unevenly distributed and mixed.

[0317] When CAC-OS is used in a transistor, the conductivity due to the first region and the insulation due to the second region work complementaryly to give CAC-OS a switching function (on / off function). In other words, CAC-OS has conductive function in part of the material, insulating function in part of the material, and semiconductor function as a whole. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I) can be achieved. on ), high field-effect mobility (μ), and good switching operation can be achieved.

[0318] Oxide semiconductors can take on diverse structures, each possessing different properties. One embodiment of the present invention may include two or more of the following: amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, CAC-OS, nc-OS, and CAAC-OS.

[0319] <Transistors containing oxide semiconductors> Next, we will explain the case where the above oxide semiconductor is used in a transistor.

[0320] By using the above-mentioned oxide semiconductor in transistors, it is possible to realize transistors with high field-effect mobility. Furthermore, it is possible to realize highly reliable transistors.

[0321] It is preferable to use an oxide semiconductor with a low carrier concentration for the transistor. For example, the carrier concentration of an oxide semiconductor is 1 × 10⁻⁶. 17 cm -3 The following is preferably 1 × 10 15 cm -3 More preferably 1 × 10 13 cm -3 More preferably 1 × 10 11 cm -3 More preferably 1 × 10 10 cm -3 It is less than 1 × 10 -9 cm -3 This concludes the explanation. Furthermore, when lowering the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film should be reduced to lower the defect level density. In this specification, a low impurity concentration and low defect level density are referred to as high-purity intrinsic or substantially high-purity intrinsic. Note that oxide semiconductors with low carrier concentrations are sometimes referred to as high-purity intrinsic or substantially high-purity intrinsic oxide semiconductors.

[0322] High-purity intrinsic or substantially high-purity intrinsic oxide semiconductor films have a low defect level density, which may result in a low trap level density.

[0323] Charges trapped in the trap levels of oxide semiconductors can take a long time to disappear and sometimes behave like fixed charges. Therefore, transistors in which channel formation regions are formed in oxide semiconductors with a high density of trap levels may exhibit unstable electrical properties.

[0324] Therefore, reducing the impurity concentration in the oxide semiconductor is effective in stabilizing the electrical characteristics of the transistor. Furthermore, in order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in adjacent films. Impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0325] <Impurities> Here, we will explain the effects of various impurities in oxide semiconductors.

[0326] In oxide semiconductors, the presence of silicon and / or carbon, which are Group 14 elements, leads to the formation of defect levels in the oxide semiconductor. Therefore, the concentrations of silicon and carbon in the oxide semiconductor and the concentrations of silicon and carbon near the interface with the oxide semiconductor (concentrations obtained by SIMS) are 2 × 10⁻¹⁰. 18 atoms / cm 3 The following is preferably 2 × 10 17 atoms / cm 3 The following applies:

[0327] When alkali metals or alkaline earth metals are present in oxide semiconductors, they can form defect levels and generate carriers. Therefore, transistors using oxide semiconductors containing alkali metals or alkaline earth metals tend to exhibit normally-on characteristics. For this reason, the concentration of alkali metals or alkaline earth metals in the oxide semiconductor obtained by SIMS should be set to 1 × 10⁻⁶. 18 atoms / cm 3 The following is preferably 2 × 10 16 atoms / cm 3 Do the following:

[0328] In oxide semiconductors, the presence of nitrogen generates electrons, which act as carriers, increasing the carrier concentration and making it easier for the semiconductor to become n-type. As a result, transistors using oxide semiconductors containing nitrogen tend to exhibit normally-on characteristics. Alternatively, the presence of nitrogen in oxide semiconductors can lead to the formation of trap levels. This can result in unstable electrical properties of the transistor. Therefore, the nitrogen concentration in oxide semiconductors obtained by SIMS should be set to 5 × 10⁻¹⁰. 19 atoms / cm 3 Less than 5 × 10 18 atoms / cm 3 More preferably 1 × 10 18 atoms / cm 3 More preferably 5 × 10 17 atoms / cm3 Do the following:

[0329] Hydrogen contained in oxide semiconductors can react with oxygen bonded to metal atoms to form water, potentially creating oxygen vacancies. When hydrogen fills these vacancies, electrons, which act as carriers, can be generated. Furthermore, some of the hydrogen can combine with oxygen bonded to metal atoms to generate electrons. Therefore, transistors using oxide semiconductors containing hydrogen tend to exhibit normally-on characteristics. For this reason, it is preferable to reduce the hydrogen content in oxide semiconductors as much as possible. Specifically, in oxide semiconductors, the hydrogen concentration obtained by SIMS should be 1 × 10⁻⁶. 20 atoms / cm 3 Less than 1 × 10 19 atoms / cm 3 Less than 5x10 18 atoms / cm 3 Less than 1 × 10 18 atoms / cm 3 Make it less than.

[0330] By using an oxide semiconductor with sufficiently reduced impurities in the channel formation region of a transistor, stable electrical characteristics can be provided.

[0331] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments. [Explanation of symbols]

[0332] 10: Layer, 20: Layer, 30: Layer, 31: Housing, 32: Opening, 34: Fixing device, 35a: Optical component, 35b: Optical component, 36a: Frame, 36b: Frame, 37: Battery, 40: Encapsulation substrate, 60: Layer, 61: Light-emitting element, 61B: Light-emitting element, 61G: Light-emitting element, 61R: Light-emitting element, 61W: Light-emitting element, 80: Electronic device, 81: User, 91: External camera, 92: Battery, 100A: Semiconductor device, 100B: Semiconductor device, 100C: Semiconductor device, 100D: Semiconductor device, 100G: Semiconductor device, 103: Housing, 104: Light source, 105: Protective component, 130 B: Light-emitting element, 130G: Light-emitting element, 130R: Light-emitting element, 200: Transistor, 205: Conductor, 205a: Conductor, 205b: Conductor, 205c: Conductor, 214: Insulator, 216: Insulator, 222: Insulator, 224: Insulator, 231: Metal oxide, 231a: Metal oxide, 231b: Metal oxide, 231c: Metal oxide, 241a: Insulator, 241b: Insulator, 242a: Conductor, 242b: Conductor, 245a: Conductor, 245b: Conductor, 250: Insulator, 251: Insulating layer, 254: Insulator, 260: Conductor, 260a: Conductor, 260b: Conductor Electrode, 264B: Colored layer, 264G: Colored layer, 264R: Colored layer, 271: Protective layer, 272: Insulating layer, 273: Protective layer, 274: Insulator, 275: Gap, 276: Insulating layer, 277: Microlens array, 279: Insulator, 280: Display panel, 280L: Display panel, 280R: Display panel, 281: Insulator, 282: Circuit section, 283: Pixel circuit section, 283a: Pixel circuit, 284: Pixel section, 284a: Pixel, 284b: Pixel section, 284c: Pixel section, 285: Terminal section, 286: Wiring section, 290: FPC, 291: Substrate, 292: Substrate, 301a: Conductor, 301b: Conductor, 311: Conductor, 313: Conductor, 321: Lower electrode, 323: Insulator, 325: Upper electrode, 331: Conductor, 333: Conductor, 335: Conductor, 341: Conductor, 343: Conductor, 347: Conductor, 348: Conductor, 351: Conductor, 353: Conductor, 355: Conductor, 357: Conductor, 361: Insulator, 363: Insulator, 400C: Display device, 403: Element isolation layer, 405: Insulator, 407: Insulator, 409: Insulator, 411: Insulator, 421: Insulator, 422: Insulator, 423: Insulator, 424: Insulator, 430a: Light-emitting element,430b: Light-emitting element, 430c: Light-emitting element, 431: Transistor, 441: Transistor, 442: Transistor, 443: Conductor, 445: Insulator, 447: Semiconductor region, 449a: Low-resistance region, 449b: Low-resistance region, 451: Conductor, 453: Conductor, 454: Bump, 455: Conductor, 456: Conductor, 457: Adhesive layer, 458: Bump, 459: Adhesive layer, 461: Conductor, 462: Conductor, 465: Conductor, 701: Substrate, 702: Substrate, 712: Sealing material, 716: FPC, 730: Insulator, 732: Filling layer, 734: Insulator, 736: Colored layer, 738: Light-shielding layer, 750: Transistor, 760: Conductor, 772: Conductor Electrode, 778: Structure, 780: Anisotropic conductor, 786: EL layer, 786a: EL layer, 786b: EL layer, 786B: EL layer, 786G: EL layer, 786R: EL layer, 786W: EL layer, 788: Conductor, 790: Capacitance, 941: Retina, 942: Lens, 943: Optic nerve, 944: Optic disc, 945: Vein, 946 : Artery, 947: Vitreous body, 948: Choroid, 950: Optical system, 951: Luminescence, 951B: Light, 951G: Light, 951IR: Luminescence, 951R: Light, 4411: Luminescence layer, 4412: Luminescence layer, 4413: Luminescence layer, 4420: Layer, 4420-1: Layer, 4420-2: Layer, 4430: Layer, 4430-1: Layer, 4430-2: Layer,

Claims

1. It is an electronic device worn on the user's head. A display device having multiple pixels arranged in a matrix on a single substrate, At least one of the plurality of pixels has a transistor, a first light-emitting element, a second light-emitting element having the function of emitting infrared light, a first photodetector, and a second photodetector having the function of receiving infrared light. The first light-emitting element, the second light-emitting element, the first light-receiving element, and the second light-receiving element are arranged to be spaced apart from each other in a plan view. The display device has a function of displaying an image using the first light-emitting element, The display device has a function to detect the brightness around the eye using the first light-receiving element before photographing the user's fundus. The display device has a function to photograph the user's fundus using the second light-emitting element and the second light-receiving element. The display device comprises a first insulating layer, a first conductor having the function of a pixel electrode of the first light-emitting element, an EL layer of the first light-emitting element, a second conductor having the function of a common electrode of the first light-emitting element, a first protective layer, and a second protective layer. The first conductor has a region located above the first insulating layer, The EL layer has a region positioned above the first conductor, The second conductor has a region located above the EL layer, The first protective layer has regions that are in contact with the upper surface of the first insulating layer, the side surface of the first conductor, the side surface of the EL layer, the side surface of the second conductor, and the side surface of the second conductor. The second protective layer has a region in contact with the upper surface of the first protective layer and a region not in contact with the upper surface of the first protective layer. A gap is provided between the portion of the second protective layer that is not in contact with the upper surface of the first protective layer and the first protective layer. electronic equipment.

2. In claim 1, The aforementioned void contains a gas having one or more of the following elements: nitrogen, oxygen, carbon dioxide, and Group 18 elements. electronic equipment.

3. In claim 1 or claim 2, The first protective layer comprises indium gallium oxide or indium gallium zinc oxide. electronic equipment.

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