Light-emitting device

Abstract

To provide a light-emitting device that suppresses variations in brightness between pixels caused by variations in the threshold voltage of transistors. [Solution] The device comprises at least a transistor, a first wire, a second wire, a first switch, a second switch, a third switch, a fourth switch, a capacitive element, and a light-emitting element. The first switch has the function of selecting conduction or non-conductivity between the first wire and one electrode of the capacitive element. The other electrode of the capacitive element is connected to either the source or the drain of the transistor. The second switch connects the second wire to the gate of the transistor and The third switch has the function of selecting conduction or non-conductivity between one electrode of the capacitive element and the gate of the transistor. The fourth switch has the function of selecting conduction or non-conductivity between one of the source and drain of the transistor and the anode of the light-emitting element.

Description

[Technical Field]

[0001] The present invention relates to a light-emitting device in which transistors are provided in each pixel. [Background technology]

[0002] Display devices using light-emitting elements offer high visibility and are ideal for thin designs, but they also have limitations in terms of viewing angle. Because it lacks a display, it replaces CRT (cathode ray tube) and liquid crystal display devices. It is attracting attention as a device. Active matrix type display devices using light-emitting elements are The proposed configurations vary by manufacturer, but typically include at least a light-emitting element, A transistor (switching transistor) that controls the input of the video signal to the pixel, A transistor (driving transistor) that controls the current value supplied to the light-emitting element, It is provided in the pixel.

[0003] By making all the transistors provided in the pixel the same polarity, the transistor manufacturing process In this process, some steps, such as adding impurity elements to impart conductivity to the semiconductor film, are omitted. It is possible. Patent Document 1 below describes a pixel composed solely of n-channel transistors. This document describes the light-emitting element type display. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2003-195810 [Overview of the project] [Problems that the invention aims to solve]

[0005] By the way, in a light-emitting device, the drain current of the driving transistor is supplied to the light-emitting element. Therefore, if there is variation in the threshold voltage of the driving transistor between pixels, the brightness of the light-emitting element will decrease. This variation is reflected in every step. Therefore, the drive voltage should take into account the variation in threshold voltage. A proposed pixel configuration that can correct the transistor current value improves the image quality of light-emitting devices. This is an important issue in terms of measurement.

[0006] Furthermore, generally speaking, the conductive film used as the anode of a light-emitting element is the same as the conductive film used as the cathode of a light-emitting element. Its surface is less susceptible to oxidation in the atmosphere than that of an electroluminescent film. Moreover, it can be used as the anode of a light-emitting element. The conductive film used is usually formed using the sputtering method, and therefore contains E When an anode is formed on the L layer, the EL layer is susceptible to damage due to sputtering. A light-emitting element having a structure in which the anode, EL layer, and cathode are stacked in that order has a simple manufacturing process. Yes, and high luminous efficiency can be easily obtained. However, an n-channel type drive is used for the light-emitting element of the above structure. When combining drive transistors, the source of the drive transistor is in contact with the anode of the light-emitting element. This continues. Therefore, as the light-emitting material deteriorates, the voltage between the anode and cathode of the light-emitting element increases. Then, in the drive transistor, the source potential rises, and the voltage between the gate and source (gate The drain current of the drive transistor decreases, i.e., the light emission. The current supplied to the element decreases, and the brightness of the light-emitting element decreases.

[0007] Based on the technical background described above, the present invention addresses the variation in the threshold voltage of the drive transistor. One of the objectives is to provide a light-emitting device that suppresses variations in brightness between pixels. That is, one of the problems of the present invention is to provide a light-emitting device capable of suppressing a decrease in the luminance of a light-emitting element due to deterioration of an EL layer. is one of the problems.

Means for Solving the Problems

[0008] One aspect of the light-emitting device of the present invention includes at least a transistor, a first wiring, a second wiring, a first switch, a second switch, a third switch, a fourth switch, a capacitive element, and a light-emitting element. The first switch has a function of selecting conduction or non-conduction between the first wiring and one of a pair of electrodes of the capacitive element. One of the pair of electrodes of the capacitive element is connected to one of the source and drain of the transistor. The second switch has a function of selecting conduction or non-conduction between the second wiring and the gate of the transistor. The third switch has a function of selecting conduction or non-conduction between one of the pair of electrodes of the capacitive element and the gate of the transistor. The fourth switch has a function of selecting conduction or non-conduction between one of the source and drain of the transistor and the anode of the light-emitting element. The fourth switch has a function of selecting conduction or non-conduction between one of the source and drain of the transistor and the anode of the light-emitting element. The fourth switch has a function of selecting conduction or non-conduction between one of the source and drain of the transistor and the anode of the light-emitting element. has.

[0009] Alternatively, one aspect of the light-emitting device of the present invention includes at least a transistor, a first wiring, a second wiring, a third wiring, a first switch, a second switch, a third switch, a fourth switch, a capacitive element, and a light-emitting element. The first switch has a function of selecting conduction or non-conduction between the first wiring and one of a pair of electrodes of the capacitive element. The other of the pair of electrodes of the capacitive element is connected to one of the source and drain of the transistor and the anode of the light-emitting element. The second switch is between the second wiring and the gate of the transistor. connected to one of the source and drain of the transistor and the anode of the light-emitting element. The second switch has a function of selecting conduction or non-conduction between the second wiring and the gate of the transistor. It has a function of selecting conduction or non - conduction between them. The third switch has a function of selecting conduction or non - conduction between one of the pair of electrodes of the capacitive element and the gate of the transistor. The fourth switch has a function of selecting conduction or non - conduction between one of the source and drain of the transistor and the third wiring. Note that the above - mentioned switch is an element having a function of controlling the supply of current or potential, and for example,

[0010] an electrical switch or a mechanical switch can be used. Specifically, it may be composed of a transistor, a diode, etc. Also, the switch may be a logic circuit combining transistors. In the light - emitting device according to one aspect of the present invention, with the above configuration, a voltage higher than the threshold voltage of the driving transistor and lower than the voltage obtained by adding the threshold voltage to the voltage between the source and drain of the driving transistor can be applied between the gate and source of the driving transistor. In the state where the above - mentioned voltage is applied, by making the source of the driving transistor floating (floating state), the threshold voltage can be obtained between the gate and source of the driving transistor. And, while keeping the source floating (floating state), when the voltage of the image signal is applied to the gate, a voltage obtained by adding the threshold voltage to the voltage of the image signal is applied between the gate and source of the driving transistor. The light - emitting element is supplied with a current having a value corresponding to the gate voltage of the driving transistor and performs grayscale display.

[0011]

Advantages of the Invention

[0012] In the light - emitting device according to one aspect of the present invention, the threshold voltage of the transistor is added to the voltage of the image signal.​​​​​​​​​​​ The potential obtained by doing so can be applied to the gate electrode of the transistor. Therefore, By correcting the threshold voltage and the anode potential, it is possible to improve the image quality of the light-emitting device. ru. [Brief explanation of the drawing]

[0013] [Figure 1] Pixel circuit diagram. [Figure 2] A timing chart showing the operation of pixels. [Figure 3] A diagram illustrating the operation of pixels. [Figure 4] A timing chart showing the operation of pixels. [Figure 5] A diagram illustrating the operation of pixels. [Figure 6] Top view of a pixel. [Figure 7] Cross-sectional view of a pixel. [Figure 8] Top view of a pixel. [Figure 9] Cross-sectional view of a pixel. [Figure 10] Cross-sectional view of a pixel. [Figure 11] Cross-sectional view of a pixel. [Figure 12] A perspective view of the panel. [Figure 13] A diagram of an electronic device. [Figure 14] A diagram illustrating the structure of an oxide semiconductor. [Figure 15] A diagram illustrating the structure of an oxide semiconductor. [Figure 16] A diagram illustrating the structure of an oxide semiconductor. [Figure 17] A diagram showing the results of the simulation. [Figure 18] A diagram showing the results of the simulation. [Modes for carrying out the invention]

[0014] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is... Not limited to the following description, the present invention may have forms and characteristics that do not depart from the spirit and scope of the invention. Those skilled in the art will readily understand that the details can be modified in various ways. Therefore, the present invention This shall not be interpreted as being limited to the contents of the embodiments described below.

[0015] In this specification, the light-emitting device refers to a panel in which light-emitting elements are formed on each pixel, and the panel This category includes modules that have ICs, including controllers, mounted on them.

[0016] (Embodiment 1) Figure 1(A) shows, as an example, the configuration of a pixel 100 in a light-emitting device according to one aspect of the present invention. show.

[0017] Pixel 100 comprises transistors 11 to 15, a capacitive element 16, and a light-emitting element 1 It has 7. Note that in Figure 1(A), transistors 11 to 15 are n channels. This example shows the case of a flannel-type filter.

[0018] Transistor 12 conducts between the wiring SL and one of the pair of electrodes of the capacitive element 16. Alternatively, it has the function of selecting non-conductivity. The other of the pair of electrodes of the capacitive element 16 is a tra It is connected to either the source or the drain of transistor 11. Transistor 13 is connected to the wiring IL It has the function of selecting conduction or non-conductivity between it and the gate of transistor 11. The transistor 14 connects one of the pair of electrodes of the capacitive element 16 to the gate of the transistor 11. It has the function of selecting conduction or non-conductivity between it and the transistor. Transistor 15 is a transistor Select whether to conduct or not conduct between one of the sources and drains of 11 and the anode of the light-emitting element 17. It has a selection function.

[0019] Furthermore, in Figure 1(A), the source and the other drain of transistor 11 are connected to wiring VL. It continues.

[0020] Furthermore, the selection of conduction or non-conductivity in transistor 12 is determined by the gate of transistor 12. Determined by the potential of the wiring G1 connected to it. Conduction or non-conductivity in transistor 13 The selection is determined by the potential of the wiring G1 connected to the gate of transistor 13. The selection of conduction or non-conductivity in transistor 14 is connected to the gate of transistor 14. Determined by the potential of wiring G2. The selection of conduction or non-conductivity in transistor 15 is determined by This is determined by the potential of the wiring G3 connected to the gate of transistor 15.

[0021] In this specification, "connection" means an electrical connection, where current, voltage, or potential is... This corresponds to a state where it can be supplied or transmitted. Therefore, a connected state is a direct connection. It does not necessarily refer to a state in which current, voltage, or potential is available or transmitted. To enable transmission, elements such as wiring, conductive films, resistors, diodes, and transistors are used. This category also includes situations where the connection is indirect.

[0022] Furthermore, even if components that appear independent on the circuit diagram are connected to each other, in reality For example, when a part of the wiring functions as an electrode, one conductive film can function as an electrode for multiple components. It may also have multiple functions. In this specification, connection means a single conductive film. However, this category also includes cases where a component possesses the functions of multiple other components.

[0023] The light-emitting element 17 has an anode, a cathode, and an EL layer provided between the anode and the cathode. The layers consist of one or more layers, and within these layers are luminescent materials. It contains at least a light layer. The EL layer is the potential between the cathode and anode, with the cathode as the reference point. The difference is due to the current supplied when it exceeds the threshold voltage Vthe of the light-emitting element 17. Ctroluminescence is obtained. Electroluminescence is obtained from the singlet excited state. Emission (fluorescence) when returning to the ground state and emission (phosphorescence) when returning from the triplet excited state to the ground state ) is included.

[0024] Furthermore, the source and drain of a transistor are related to the polarity of the transistor and the source and drain. The name changes depending on the potential applied to the input. Generally, n-channel In a transistor, the side to which the lower potential is applied is called the source. The side to which a higher potential is applied is called the drain. Also, in a p-channel transistor... In this scenario, of the source and drain, the one to which a lower potential is applied is called the drain, and the one to which a higher potential is applied is called the drain. The given component is called the source. For convenience, in this specification, the source and drain are fixed. Sometimes, the connection relationships of transistors are explained by assuming that they are actually above The terms "source" and "drain" are reversed according to the relationship between the stored potentials.

[0025] Next, Figure 1(B) shows another example of a pixel 100 in a light-emitting device according to one aspect of the present invention. This indicates.

[0026] Pixel 100 comprises transistors 11 to 15, a capacitive element 16, and a light-emitting element 1 It has 7. Note that in Figure 1(B), transistors 11 to 15 are n channels. This example shows the case of a flannel-type filter.

[0027] Transistor 12 conducts between the wiring SL and one of the pair of electrodes of the capacitive element 16. Alternatively, it has the function of selecting non-conductivity. The other of the pair of electrodes of the capacitive element 16 is a tra The transistor is connected to one of the source and drain terminals of the inverter 11 and to the anode of the light-emitting element 17. The transistor 13 selects whether to conduct or not conduct between the wiring IL and the gate of transistor 11. It has the function of having one of the pair of electrodes of the capacitive element 16 and It has the function of selecting conductivity or non-conductivity between the gate of the transistor 11. The transistor 15 is connected to one of the source and drain of the transistor 11 and the anode of the light-emitting element 17, and It has the function of selecting conductivity or non-conductivity with respect to line RL. Also, the transistor 11 The other end of the drain is connected to wiring VL.

[0028] Furthermore, the selection of conduction or non-conductivity in transistor 12 is determined by the gate of transistor 12. Determined by the potential of the wiring G1 connected to it. Conduction or non-conductivity in transistor 13 The selection is determined by the potential of the wiring G1 connected to the gate of transistor 13. The selection of conduction or non-conductivity in transistor 14 is connected to the gate of transistor 14. Determined by the potential of wiring G2. The selection of conduction or non-conductivity in transistor 15 is determined by This is determined by the potential of the wiring G3 connected to the gate of transistor 15.

[0029] In Figures 1(A) and 1(B), transistors 11 to 15 are, It is sufficient to have a gate on at least one side of the semiconductor film, but if the semiconductor film is sandwiched in between... It may have a pair of gates. One of the pair of gates may be the front gate, and the other may be the front gate. If we consider this as the back gate, the back gate may be in a floating state, and the potential It is also acceptable if the front gate and back gate are provided by others. In the latter case, the front gate and back gate The same potential can be applied to the gate, or only the back gate can have a fixed potential such as ground potential. A constant potential can be applied. By controlling the height of the potential applied to the back gate, The threshold voltage of the transistor can be controlled. Furthermore, by providing a back gate, The channel formation region increases, enabling an increase in drain current. By creating a void, a depletion layer is more likely to form in the semiconductor film, thus improving the S value. can.

[0030] Furthermore, in Figures 1(A) and 1(B), transistors 11 through 15 are all n This example illustrates the case of a channel type. Transistors 11 through 15 are all the same. In the case of heteropolarity, the process of manufacturing a transistor involves imparting a single conductivity to the semiconductor film. Some steps, such as the addition of pure elements, can be omitted. However, this applies to one aspect of the present invention. In the light-emitting device, it is not necessarily the case that all transistors 11 to 15 are of the n-channel type. It is not necessary. The anode of the light-emitting element 17 is connected to either the source or the drain of the transistor 15. When connected, it is preferable that at least transistor 11 be of n-channel type. The cathode of the light-emitting element 17 is connected to either the source or the drain of the transistor 15. In this case, it is desirable that at least transistor 11 be of the p-channel type.

[0031] Furthermore, when the transistor 11 is operated in the saturation region when current is flowing, the channel length and It is desirable to make the channel width longer than transistors 12 through 15. By increasing the channel length or channel width, the characteristics in the saturation region become flatter. This can reduce the kink effect. Alternatively, the channel length or channel width can be increased. As a result, transistor 11 can pass a large current even in the saturation region. ru.

[0032] Furthermore, in Figures 1(A) and 1(B), transistors 11 to 15 are single In the case of having a gate, it is a single-gate structure having a single channel formation region. Although examples are shown, the present invention is not limited to this configuration. Transistors 11 to Transistors One or all of the sta15 have multiple electrically connected gates, It may also be a multi-gate structure having a number of channel-forming regions.

[0033] Next, the operation of pixel 100 shown in Figure 1(A) will be explained.

[0034] Figure 2 shows the potential of wiring G1 to G3 connected to pixel 100 shown in Figure 1(A), and the wiring The potential Vdata supplied to line SL is illustrated in the timing chart. However, Figure 2 The timing chart shown is for transistors 11 to 15 in an n-channel type. This illustrates one case. As shown in Figure 2, the operation of pixel 100 shown in Figure 1(A) is primarily The first action in period 1, the second action in period 2, and the third action in period 3 It can be divided.

[0035] First, let's explain the first operation that takes place during period 1. During period 1, wiring G1 is connected to A low level potential is applied to wiring G2, and a high level potential is applied to wiring G3. The potential of the bell is applied. Therefore, transistor 15 becomes conductive, and transistor 1 Transistors 2 through 14 become non-conductive.

[0036] Furthermore, the wiring VL is given a potential Vano, and the cathode of the light-emitting element 17 is given a potential Vcat. The potential Vano is obtained by adding the threshold voltage Vthe of the light-emitting element 17 to the potential Vcat. It is assumed to be higher than the potential. Furthermore, the threshold voltage Vthe of the light-emitting element 17 is assumed to be 0 below. Let's assume that.

[0037] Figure 3(A) shows the operation of pixel 100 during period 1. Note that in Figure 3(A), the transistor Transistors 12 through 15 are indicated as switches. During period 1, the above operation occurs. As a result, one of the source and drain of transistor 11 (shown as node A in the diagram) The potential is obtained by adding the threshold voltage Vthe of the light-emitting element 17 to the potential Vcat. In Figure 3(A) Assuming that the threshold voltage Vthe is 0, the potential at node A is potential Vcat This is the result.

[0038] Next, we will explain the second operation that takes place during period 2. During period 2, wiring G1 A high-level potential is applied to wiring G2, and a low-level potential is applied to wiring G3. A potential level is applied. Therefore, transistors 12 and 13 enter a conductive state. As a result, transistors 14 and 15 become non-conductive.

[0039] Furthermore, when transitioning from period 1 to period 2, the potential applied to wiring G1 changes from a low level to a high level. After switching to the 'L' setting, the potential supplied to wiring G3 is switched from high level to low level. It is desirable to do so. With the above configuration, by switching the potential supplied to wiring G1, the node This prevents the potential at point A from fluctuating.

[0040] Furthermore, the wiring VL is given a potential Vano, and the cathode of the light-emitting element 17 is given a potential Vcat. It is obtained. Then, potential V0 is given to wiring IL, and the potential Vd of the image signal is given to wiring SL. ata is given. Note that the potential V0 is the threshold voltage V of transistor 11 at potential Vcat. The potential is higher than the sum of the threshold voltages Vthe of th and the light-emitting element 17, and the potential Vano is higher. It is desirable that the threshold voltage Vth of the transistor 11 is lower than the sum of the two potentials.

[0041] Figure 3(B) shows the operation of pixel 100 during period 2. Note that in Figure 3(B), the transistor Transistors 12 through 15 are indicated as switches. During period 2, the above operation This applies a potential V0 to the gate of transistor 11 (shown as node B in the diagram). Therefore, transistor 11 becomes conductive. Thus, the capacitive element is connected via transistor 11. 16 charges are released, and the potential of node A, which was Vcat, begins to rise. Ultimately, when the potential of node A becomes potential V0-Vth, that is, when transistor 11's potential When the voltage drops to the threshold voltage Vth, transistor 11 becomes non-conductive. Furthermore, a potential Vdata is applied to one electrode of the capacitive element 16 (shown as node C in the diagram). It is possible.

[0042] Next, we will explain the third operation that takes place during period 3. During period 3, wiring G1 A low potential is applied to wiring G2, and a high potential is applied to wiring G3. A potential level is applied. Therefore, transistors 14 and 15 enter a conductive state. As a result, transistors 12 and 13 become non-conductive.

[0043] Furthermore, when transitioning from period 2 to period 3, the potential applied to wiring G1 changes from high level to low level. After switching to the new setting, the potential applied to wiring G2 and wiring G3 is changed from low level to high level. It is desirable to switch to the above configuration. This prevents the potential at node A from fluctuating.

[0044] Furthermore, the wiring VL is given a potential Vano, and the cathode of the light-emitting element 17 is given a potential Vcat. It can be obtained.

[0045] Figure 3(C) shows the operation of pixel 100 during period 3. Note that in Figure 3(C), the transistor Transistors 12 through 15 are indicated as switches. During period 3, the above operation As a result, a potential Vdata is applied to node B, and the gate voltage of transistor 11 becomes Vdata - V0 + Vth. Therefore, the gate voltage of transistor 11 is the threshold voltage. The value can be set to take Vth into account. With the above configuration, the threshold of transistor 11 To prevent variations in the voltage value Vth from affecting the current value supplied to the light-emitting element 17. This is possible. Alternatively, even if transistor 11 deteriorates and the threshold voltage Vth changes, the above changes can be made. This prevents the current supplied to the light-emitting element 17 from being affected. It can reduce unevenness and enable high-quality display.

[0046] Next, the operation of pixel 100 shown in Figure 1(B) will be explained.

[0047] Figure 4 shows the potential of wiring G1 to G3 connected to pixel 100 shown in Figure 1(B), and the wiring The potential Vdata supplied to line SL is illustrated in the timing chart. However, Figure 4 The timing chart shown is for transistors 11 to 15 in an n-channel type. This illustrates one case. As shown in Figure 4, the operation of pixel 100 shown in Figure 1(B) is primarily The first action in period 1, the second action in period 2, and the third action in period 3 It can be divided.

[0048] First, let's explain the first operation that takes place during period 1. During period 1, wiring G1 is connected to A low level potential is applied to wiring G2, and a high level potential is applied to wiring G3. The potential of the bell is applied. Therefore, transistor 15 becomes conductive, and transistor 1 Transistors 2 through 14 become non-conductive.

[0049] Furthermore, the wiring VL is given a potential Vano, and the cathode of the light-emitting element 17 is given a potential Vcat. The potential Vano is obtained by setting the threshold voltage Vthe of the light-emitting element 17 to the potential V It is assumed that the potential is higher than the potential added to cat. Furthermore, a potential V1 is applied to the wiring RL. The potential V1 is obtained by adding the threshold voltage Vthe of the light-emitting element 17 to the potential Vcat. It is desirable that the voltage is also low. By setting the potential V1 to the above value, the light-emitting element 1 in period 1 This prevents current from flowing through 7.

[0050] Figure 5(A) shows the operation of pixel 100 during period 1. Note that in Figure 5(A), the transistor Transistors 12 through 15 are indicated as switches. During period 1, the above operation occurs. As a result, one of the source and drain of transistor 11 (shown as node A in the diagram) A potential V1 is applied.

[0051] Next, we will explain the second operation that takes place during period 2. During period 2, wiring G1 A high-level potential is applied to wiring G2, and a low-level potential is applied to wiring G3. A potential level is applied. Therefore, transistors 12 and 13 enter a conductive state. As a result, transistors 14 and 15 become non-conductive.

[0052] Furthermore, when transitioning from period 1 to period 2, the potential applied to wiring G1 changes from a low level to a high level. After switching to the 'L' setting, the potential supplied to wiring G3 is switched from high level to low level. It is desirable to do so. With the above configuration, by switching the potential supplied to wiring G1, the node This prevents the potential at point A from fluctuating.

[0053] Furthermore, the wiring VL is given a potential Vano, and the cathode of the light-emitting element 17 is given a potential Vcat. It is obtained. Then, potential V0 is given to wiring IL, and the potential Vd of the image signal is given to wiring SL. ata is given. Note that the potential V0 is, as mentioned above, the potential Vcat is a transistor The potential is higher than the sum of the threshold voltage Vth of 11 and the threshold voltage Vthe of the light-emitting element 17. It is desirable that the potential Vano is lower than the potential obtained by adding the threshold voltage Vth of transistor 11. However, unlike the case of pixel 100 shown in Figure 1(A), pixel 10 shown in Figure 1(B) If 0, the anode of the light-emitting element 17 and one of the source and drain of the transistor 11 They are connected. Therefore, the current value supplied to the light-emitting element 17 during period 2 is kept small. Therefore, in the case of pixel 100 shown in Figure 1(B), it is different from the case of pixel 100 shown in Figure 1(A). Furthermore, it is desirable to set the potential V0 to a low value.

[0054] Figure 5(B) shows the operation of pixel 100 during period 2. Note that in Figure 5(B), the transistor Transistors 12 through 15 are indicated as switches. During period 2, the above operation This applies a potential V0 to the gate of transistor 11 (shown as node B in the diagram). Therefore, transistor 11 becomes conductive. Thus, the capacitive element is connected via transistor 11. Sixteen charges are released, and the potential of node A, which was V1, begins to rise. And finally When the potential of node A becomes potential V0-Vth, that is, the gate of transistor 11 When the voltage drops to the threshold voltage Vth, transistor 11 becomes non-conductive. A potential Vdata is applied to one electrode of the capacitive element 16 (shown as node C in the diagram). ru.

[0055] Next, we will explain the third operation that takes place during period 3. During period 3, wiring G1 A low potential is applied to wiring G2, and a high potential is applied to wiring G3. A potential of a certain level is applied. Therefore, transistor 14 becomes conductive, and the transistor Transistors 12, 13, and 15 become non-conductive.

[0056] Furthermore, when transitioning from period 2 to period 3, the potential applied to wiring G1 changes from high level to low level. After switching to the 'L' setting, the potential supplied to wiring G2 is switched from low level to high level. It is desirable to do so. With the above configuration, by switching the potential supplied to wiring G1, the node This prevents the potential at point A from fluctuating.

[0057] Furthermore, the wiring VL is given a potential Vano, and the cathode of the light-emitting element 17 is given a potential Vcat. It can be obtained.

[0058] Figure 5(C) shows the operation of pixel 100 during period 3. Note that in Figure 5(C), the transistor Transistors 12 through 15 are indicated as switches. During period 3, the above operation As a result, a potential Vdata is applied to node B, and the gate voltage of transistor 11 becomes Vdata - V0 + Vth. Therefore, the gate voltage of transistor 11 is the threshold voltage. The value can be set to take Vth into account. With the above configuration, the threshold of transistor 11 To prevent variations in the voltage value Vth from affecting the current value supplied to the light-emitting element 17. This is possible. Alternatively, even if transistor 11 deteriorates and the threshold voltage Vth changes, the above changes can be made. This prevents the current supplied to the light-emitting element 17 from being affected. It can reduce unevenness and enable high-quality display.

[0059] In addition, in the light-emitting element type display described in Patent Document 1, current is supplied to the organic EL element. The gate and drain of the transistor (Tr12) are electrically connected to determine the threshold voltage. Acquisition is being performed. Therefore, if the transistor (Tr12) is normally on, the transistor The source of the transistor (Tr12) will never be higher than the gate. Therefore, the transistor When (Tr12) is normally on, it is difficult to obtain the threshold voltage.

[0060] On the other hand, in a light-emitting device according to one embodiment of the present invention having pixels as shown in Figures 1(A) and 1(B) The source and drain of transistor 11, and the gate of transistor 11 are connected. Because they are separated by gas, their respective potentials can be controlled individually. Therefore, the second In the operation of the transistor, the potential of the source and the other drain of transistor 11 is set to the transistor It is possible to set the gate potential of 11 to a value higher than the potential obtained by adding the threshold voltage Vth. Therefore, when transistor 11 is normally on, that is, when the threshold voltage Vt When h has a negative value, the source potential in transistor 11 is The capacitive element 16 can accumulate charge until it becomes higher than the potential V0. In a light-emitting device according to one aspect of the present invention, even if transistor 11 is normally ionized, In the second operation, the threshold voltage can be obtained, and in the third operation, the threshold voltage V The gate voltage of transistor 11 can be set to a value that takes th into account.

[0061] Therefore, in a light-emitting device according to one aspect of the present invention, for example, the semiconductor film of the transistor 11 When an oxide semiconductor is used, even if transistor 11 is in a normally-on state, the display will still show This reduces noise and allows for high-quality display.

[0062] (Embodiment 2) Figure 6 shows an example of a top view of the pixel shown in Figure 1(A). Note that in Figure 6, the pixel To clearly show the layout, various insulating films are omitted, and a top view of the pixels is shown. Figure 6 clearly shows the layout of the transistors and capacitive elements in the pixel, and the anode The EL layer and cathode are omitted, and the top view of the pixel is shown.

[0063] Furthermore, Figure 7 shows cross-sectional views of the top view shown in Figure 6, along dashed lines A1-A2 and A3-A4. This indicates.

[0064] The transistor 12 has a conductive film 8 that functions as a gate on a substrate 800 having an insulating surface. 01, the gate insulating film 802 on the conductive film 801, and the gate at a position overlapping with the conductive film 801 A semiconductor film 803 is located on the insulating film 802, and functions as a source or drain. It has conductive films 804 and 805 located on the semiconductor film 803. The conductive film 801 is It also functions as wiring G1. Conductive film 804 also functions as wiring SL.

[0065] The transistor 13 has a conductive film 8 that functions as a gate on a substrate 800 having an insulating surface. 01, the gate insulating film 802 on the conductive film 801, and the gate at a position overlapping with the conductive film 801 A semiconductor film 806 is located on the insulating film 802, and functions as a source or drain. It has conductive films 807 and 808 located on the semiconductor film 806. Conductive film 807 is It is connected via a contact hole to a conductive film 809 that functions as wiring IL.

[0066] The transistor 14 has a conductive film 8 that functions as a gate on a substrate 800 having an insulating surface. 10, the gate insulating film 802 on the conductive film 810, and the gate at a position overlapping with the conductive film 810 A semiconductor film 811 is located on the insulating film 802, and functions as a source or drain. It has conductive films 805 and 808 located on the semiconductor film 811. The conductive film 810 is It also functions as wiring G2.

[0067] The transistor 11 has a conductive film 8 that functions as a gate on a substrate 800 having an insulating surface. 12, the gate insulating film 802 on the conductive film 812, and the gate at a position overlapping with the conductive film 812 A semiconductor film 813 is located on the insulating film 802, and functions as a source or drain. It has conductive films 814 and 815 located on the semiconductor film 813. The conductive film 812 is It is connected to conductive film 808. Conductive film 814 also functions as wiring VL.

[0068] The transistor 15 has a conductive film 8 that functions as a gate on a substrate 800 having an insulating surface. 16, the gate insulating film 802 on the conductive film 816, and the gate at a position overlapping with the conductive film 816 A semiconductor film 817 is located on the insulating film 802, and functions as a source or drain. It has conductive films 815 and 818 located on the semiconductor film 817. Conductive film 816 is It also functions as a G3 wiring standard.

[0069] The capacitive element 16 has a conductive film 819 on a substrate 800 having an insulating surface, and on the conductive film 819 A gate insulating film 802 is located on the gate insulating film 802 at a position where it overlaps with the conductive film 819. It has a conductive film 815. The conductive film 819 is connected to the conductive film 805.

[0070] Also, conductive film 804, conductive film 805, conductive film 807, conductive film 808, conductive film 814, conductive An insulating film 820 is formed on film 815 and conductive film 818. And insulating film 821 A conductive film 822, which functions as an anode, is provided on top. The conductive film 822 is an insulating film 8 20 and the conductive film 818 are in contact through the contact hole 823 formed in the insulating film 821. It continues.

[0071] Furthermore, an insulating film 824 having an opening that exposes a portion of the conductive film 822, 1 is provided on. On a part of the conductive film 822 and on the insulating film 824, there is an EL layer 825, A conductive film 826, which functions as a cathode, is arranged in a stacked manner. The region where 2, the EL layer 825, and the conductive film 826 overlap corresponds to the light-emitting element 17. .

[0072] Next, Figure 8 shows a top view of the pixel shown in Figure 1(A) as another example. Now, in order to clearly show the pixel layout, we will omit various insulating films and show a top view of the pixels. Figure 8 clearly shows the layout of the transistors and capacitive elements in each pixel. Therefore, the anode, EL layer, and cathode are omitted, and a top view of the pixel is shown.

[0073] Furthermore, Figure 9 shows cross-sectional views of the top view shown in Figure 8, along the dashed lines A1-A2 and A3-A4. This indicates.

[0074] The transistor 12 has a semiconductor film 901 and a semiconductor film 9 on a substrate 900 having an insulating surface. The gate insulating film 902 on 01 and the gate insulating film 90 at a position where it overlaps with the semiconductor film 901 2 is located on top of the conductive film 903 which functions as a gate, and the semiconductor film 901 has a source It has conductive films 904 and 905 connected to the drain. Conductive film 903 is It also functions as wire G1. Conductive film 904 also functions as wiring SL.

[0075] The transistor 13 has a semiconductor film 906 and a semiconductor film 9 on a substrate 900 having an insulating surface. The gate insulating film 902 on 06 and the gate insulating film 90 at a position where it overlaps with the semiconductor film 906 2 A conductive film 903 located on top and functioning as a gate, and a source having semiconductor film 906 It has conductive films 907 and 908 connected to the drain. Conductive film 907 is It is connected to the conductive film 909, which functions as wiring IL, via a contact hole.

[0076] The transistor 14 has a semiconductor film 901 and a semiconductor film 9 on a substrate 900 having an insulating surface. The gate insulating film 902 on 01 and the gate insulating film 90 at a position where it overlaps with the semiconductor film 901 2 A conductive film 911 located on top and functioning as a gate, and a source having semiconductor film 901 It has conductive films 905 and 908 connected to the drain. Conductive film 911 is It also functions as wiring G2. Note that in Figure 8, transistors 12 and 14 are Although they share one semiconductor film 901, transistors 12 and 14 are mutual It may have an independent semiconductor film.

[0077] The transistor 11 has a semiconductor film 912 and a semiconductor film 9 on a substrate 900 having an insulating surface. The gate insulating film 902 on 12 and the gate insulating film 90 at a position where it overlaps with the semiconductor film 912 2 A conductive film 913 located on top and functioning as a gate, and a source having semiconductor film 912 The conductive film 913 is connected to the conductive film 908. It continues. The conductive film 914 also functions as wiring VL.

[0078] The transistor 15 has a semiconductor film 912 and a semiconductor film 9 on a substrate 900 having an insulating surface. The gate insulating film 902 on 12 and the gate insulating film 90 at a position where it overlaps with the semiconductor film 912 2 A conductive film 915 located on top and functioning as a gate, and a source having semiconductor film 912 It has a conductive film 916 connected to the drain. The conductive film 915 also functions as wiring G3. To be able to.

[0079] The capacitive element 16 has a semiconductor film 912 on a substrate 900 having an insulating surface, and the semiconductor film 912 At a position where the upper gate insulating film 902 and the semiconductor film 912 overlap, on the gate insulating film 902 It has a conductive film 917 located at the same position. The conductive film 917 is connected to the conductive film 905.

[0080] And conductive film 904, conductive film 905, conductive film 907, conductive film 908, conductive film 914, conductive An insulating film 920 is formed on the film 916. On the insulating film 920, as the anode, A conductive film 921 is provided. The conductive film 921 is formed on the insulating film 920. It is connected to the conductive film 916 via the tact hole 922.

[0081] Furthermore, an insulating film 923 having an opening that exposes a portion of the conductive film 921, It is provided on 0. On a part of the conductive film 921 and on the insulating film 923, there is an EL layer 924, A conductive film 925, which functions as a cathode, is arranged in a stacked manner. The region where 1, the EL layer 924, and the conductive film 925 overlap corresponds to the light-emitting element 17. .

[0082] In one aspect of the present invention, transistors 11 to 15 are amorphous, microcrystalline. Semiconductors such as silicon or germanium, which are polycrystalline or single-crystal, are used in semiconductor films. It is also acceptable if wide-bandgap semiconductors such as oxide semiconductors are used in the semiconductor film. You can.

[0083] The semiconductor film of transistors 11 to 15 is amorphous, microcrystalline, polycrystalline, or monocrystalline. When semiconductors such as silicon or germanium are used, one conduction is imparted. An impurity element is added to the semiconductor film to form an impurity region that functions as a source or drain. A region is formed. For example, by adding phosphorus or arsenic to the semiconductor film, an n-type conductive region is formed. An impurity region having the above can be formed. Also, for example, boron can be added to the semiconductor film. By adding this, a p-type conductive impurity region can be formed.

[0084] When an oxide semiconductor is used for the semiconductor film of transistors 11 to 15, A dopant is added to the semiconductor film to create impurity regions that function as sources or drains. It may be formed. Ion implantation can be used for dopant addition. For example, noble gases such as helium, argon, and xenon, as well as nitrogen, phosphorus, arsenic, and antimicrobial compounds. Group 15 elements such as mon can be used. For example, nitrogen can be used as a dopant. In that case, the concentration of nitrogen atoms in the impurity region is 5 × 10 19 / cm 3 The above 1 x 10 22 / c m 3 The following is preferable:

[0085] Furthermore, silicon semiconductors are produced using vapor phase growth methods such as plasma CVD or sputtering. Amorphous silicon produced by the annealing method, amorphous silicon subjected to treatments such as laser annealing Hydrogen ions and other substances are implanted into polycrystalline silicon and single-crystal silicon wafers to form a crystallized surface layer. Single-crystal silicon from which a portion has been peeled off can be used.

[0086] Furthermore, oxide semiconductors include indium oxide, tin oxide, zinc oxide, and oxides of binary metals. These include In-Zn oxides, Sn-Zn oxides, Al-Zn oxides, and Zn-Mg oxides. Acids of oxides, Sn-Mg oxides, In-Mg oxides, In-Ga oxides, and ternary metals In-Ga-Zn oxides (also written as IGZO) and In-Al-Zn acids are examples of these compounds. In-Sn-Zn oxides, Sn-Ga-Zn oxides, Al-Ga-Zn oxides Substances, Sn-Al-Zn oxides, In-Hf-Zn oxides, In-La-Zn oxides In-Ce-Zn oxides, In-Pr-Zn oxides, In-Nd-Zn oxides, In-Sm-Zn oxides, In-Eu-Zn oxides, In-Gd-Zn oxides, I n-Tb-Zn oxides, In-Dy-Zn oxides, In-Ho-Zn oxides, In -Er-Zn oxides, In-Tm-Zn oxides, In-Yb-Zn oxides, In- Lu-Zn ​​oxides, In-Sn-Ga-Zn oxides which are oxides of quaternary metals, In -Hf-Ga-Zn oxides, In-Al-Ga-Zn oxides, In-Sn-Al-Z n-based oxides, In-Sn-Hf-Zn-based oxides, and In-Hf-Al-Zn-based oxides are used. It is possible.

[0087] For example, an In-Ga-Zn oxide is an oxide that contains In, Ga, and Zn. This is the meaning, and the ratio of In, Ga, and Zn is irrelevant. Also, the metal elements other than In, Ga, and Zn are not relevant. It's okay if it contains some raw ingredients.

[0088] In addition, as an oxide semiconductor, InMO3(ZnO) m (m > 0, and m is not an integer) Materials represented by may also be used. Note that M is selected from Ga, Fe, Mn, and Co. It represents one or more metallic elements. Also, as an oxide semiconductor, In2SnO5 (ZnO) nMaterials expressed as (n>0 and n is an integer) may also be used.

[0089] For example, In:Ga:Zn = 1:1:1 (= 1 / 3:1 / 3:1 / 3) or In:G In-Ga-Zn system oxidation with atomic ratio a:Zn=2:2:1 (=2 / 5:2 / 5:1 / 5) Oxides with a similar composition to the substance can be used. Alternatively, In:Sn:Zn=1: 1:1(=1 / 3:1 / 3:1 / 3), In:Sn:Zn=2:1:3(=1 / 3:1 / 6:1 / 2) or In:Sn:Zn=2:1:5 (=1 / 4:1 / 8:5 / 8) It is advisable to use In-Sn-Zn oxides with a specific ratio or oxides with a similar composition.

[0090] Furthermore, to reduce variations in the electrical characteristics of transistors using the oxide semiconductor, As vilizers, tin (Sn), hafnium (Hf), aluminum (Al), zirconium It is preferable that it contains nium (Zr) and titanium (Ti). Other stabilizers include: Lanthanoids include lanthanum (La), cerium (Ce), praseodymium (Pr), and ne Odymium (Nd), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er) ), one of the following: thulium (Tm), ytterbium (Yb), lutetium (Lu) Rui may have multiple species.

[0091] Furthermore, impurities such as water or hydrogen, which act as electron donors, are reduced, and acid Oxide semiconductors with reduced elemental defects (purified OS) It is a type i (intrinsic semiconductor) or very close to a type i. Therefore, the above oxide semiconductor is used Transistors have the characteristic of having a remarkably low off-current. Also, oxide semiconductor van The voltage gap is 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more. The concentration of impurities such as water or hydrogen is sufficiently reduced, and oxygen deficiency is also reduced. By using an oxide semiconductor film that has been purified by this process, the off-current of the transistor can be reduced. It can be lowered.

[0092] Specifically, transistors using highly purified oxide semiconductors as semiconductor films have a low off-current. This can be proven through various experiments. For example, if the channel width is 1 × 10⁻⁶ 6 micrometers Even with a channel length of 10 μm, the voltage between the source electrode and the drain electrode (drain electrode) When the voltage is in the range of 1V to 10V, the off-current is measured by a semiconductor parameter analyzer. Below the limit, i.e., 1 × 10⁻⁶ -13 It is possible to obtain the characteristic of being A or less. In this case, The off-current, which corresponds to the value obtained by dividing the f-current by the transistor's channel width, is 100 Hz / μF. It can be seen that it is less than or equal to m. Also, by connecting the capacitive element and the transistor, the current flows through the capacitive element. A circuit is used to control the charge flowing out from an input or capacitive element using the transistor, and the off-power Current measurements were performed. In these measurements, a highly purified oxide semiconductor film was applied to the transistor. Used in the channel formation region, the transition of the charge amount per unit time of the capacitive element is used to determine the transient. The off-current of the transistor was measured. As a result, the voltage between the source and drain electrodes of the transistor was measured. It was found that an even lower off-current of several tens of yA / μm can be obtained when the voltage is 3V. Therefore, transistors that use a highly purified oxide semiconductor film in the channel formation region are The off-current is significantly lower compared to transistors using crystalline silicon.

[0093] Unless otherwise specified, in this specification, off-current refers to the off-current of an n-channel transistor. In this case, with the drain at a higher potential than the source and gate, the potential of the source is based When the gate potential is 0 or less, the current flowing between the source and drain is... This means that. Alternatively, in this specification, off-current refers to a p-channel transistor. In this case, with the drain at a lower potential than the source and gate, the potential of the source is based When the gate potential is greater than or equal to zero, the current flowing between the source and drain It means that.

[0094] For example, oxide semiconductor films include In (indium), Ga (gallium), and Zn ( It can be formed by sputtering using a target containing zinc. When depositing a Zn-based oxide semiconductor film by sputtering, preferably, the atomic ratio is In :Ga:Zn=1:1:1, 4:2:3, 3:1:2, 1:1:2, 2:1:3, or A target of an In-Ga-Zn oxide system, represented by the ratio 3:1:4, is used. To deposit an oxide semiconductor film using an In-Ga-Zn-based oxide target having the following properties. This makes it easier for polycrystalline or CAAC to form. Also, a t The filling rate of the container is 90% or more and 100% or less, preferably 95% or more and less than 100%. By using a target with a high packing density, the deposited oxide semiconductor film becomes a dense film. ru.

[0095] Furthermore, when using an In-Zn-based oxide material as the oxide semiconductor, the target used The atomic ratio of the metal elements is In:Zn = 50:1 to 1:2 (converted to a mole ratio of In2 O3:ZnO = 25:1 to 1:4), preferably In:Zn = 20:1 to 1:1 (number of moles) When converted to a ratio, In2O3:ZnO = 10:1 to 1:2), and more preferably In:Zn =15:1~1.5:1 (Converted to a mole ratio of In2O3:ZnO = 15:2~3:4) ) For example, a target used in the formation of an oxide semiconductor film which is an In-Zn oxide. When the atomic ratio is In:Zn:O=X:Y:Z, assume Z>1.5X+Y. By keeping the rate within the above range, it is possible to improve mobility.

[0096] Specifically, the oxide semiconductor film is processed by holding the substrate in a processing chamber that is kept under reduced pressure, and then processing... While removing residual moisture in the laboratory, sputtered gas from which hydrogen and moisture have been removed is introduced, and the above-mentioned It can be formed using a film-forming agent. During film formation, the substrate temperature should be between 100°C and 600°C. Alternatively, the temperature can be between 200°C and 400°C. By depositing the film while heating the substrate... This allows for a reduction in the impurity concentration contained in the deposited oxide semiconductor film. Damage caused by tarring is reduced. To remove residual moisture in the processing chamber, an adsorption type It is preferable to use a vacuum pump. For example, a cryopump, ion pump, or titanium pump. It is preferable to use a breech pump. Furthermore, a turbopump is preferred as the exhaust means. A cold trap may be added to the system. The deposition chamber is evacuated using a cryopump. Then, for example, hydrogen atoms, water (H2O) and other compounds containing hydrogen atoms (more preferably carbon Because compounds containing elementary atoms are also exhausted, the oxide semiconductor film deposited in the processing chamber contains The concentration of impurities can be reduced.

[0097] Furthermore, in oxide semiconductor films formed by sputtering, etc., there may be water or hydrogen as an impurity. It may contain a large amount of (hydroxyl groups). Water or hydrogen forms donor levels. Because it is easily oxidized, it is an impurity for oxide semiconductors. Therefore, in one aspect of the present invention, To reduce impurities such as water or hydrogen in a semiconductor film (dehydration or dehydrogenation) For oxide semiconductor films, under reduced pressure, under an inert gas atmosphere such as nitrogen or a rare gas, acid Under a gas atmosphere or in ultra-dry air (CRDS (cavity ring-down laser spectroscopy) The moisture content measured using a dew point meter of the ) type is 20 ppm or less (equivalent to a dew point of -55°C). The heat treatment is performed in an atmosphere (preferably 1 ppm or less, preferably 10 ppb or less of air) To administer.

[0098] By applying heat treatment to the oxide semiconductor film, water or hydrogen is removed from the oxide semiconductor film. This is possible. Specifically, a substrate at 250°C to 750°C, preferably 400°C or higher. The heat treatment should be performed at a temperature below the strain point. For example, 500°C for 3 to 6 minutes. It should be done to a certain extent. If the RTA method is used for heat treatment, dehydration or dehydrogenation can be performed in a short time. Therefore, processing can be performed even at temperatures exceeding the strain point of the glass substrate.

[0099] Furthermore, the above heat treatment causes oxygen to be removed from the oxide semiconductor film, and oxygen remains in the oxide semiconductor film. Defects may be formed. Therefore, in one aspect of the present invention, the g An insulating film containing oxygen is used as the insulating film, such as a galvanic insulating film. After forming the film, heat treatment is applied to supply oxygen from the insulating film to the oxide semiconductor film. This configuration reduces the oxygen vacancies that serve as donors and is contained in the oxide semiconductor film. The oxide semiconductor can satisfy the stoichiometric composition ratio. The oxide semiconductor film contains It is preferable that the mixture contains an amount of oxygen exceeding the stoichiometric composition ratio. The body membrane can be made closer to type i, reducing variations in the electrical characteristics of transistors due to oxygen deficiency. This can reduce noise and improve electrical characteristics.

[0100] Furthermore, the heat treatment to supply oxygen to the oxide semiconductor film is performed using nitrogen, ultra-dry air, or dilute air. In a gaseous atmosphere (such as argon or helium), preferably at a temperature of 200°C to 400°C. The following steps should be performed at a temperature between 250°C and 350°C. The gas mentioned above must contain less than 20 ppm of water. Preferably, the concentration is 1 ppm or less, and more preferably 10 ppb or less.

[0101] Furthermore, oxide semiconductors may be amorphous (non-crystalline) or crystalline. This is also acceptable. In the latter case, it may be a single crystal, a polycrystalline material, or a structure in which a part is crystalline. It may be a solid, or it may be a structure that includes a crystalline part within the amorphous, or non-amorphous It can also be a s. As an example of a structure in which a part is crystalline, it is c-axis oriented and ab-plane, surface It has a triangular or hexagonal atomic arrangement when viewed from a direction perpendicular to the surface or interface, and perpendicular to the c-axis. When viewed from a straight direction, the metal atoms are arranged in layers or the metal atoms and oxygen atoms are arranged in layers, a On the b-plane, the oxide contains crystals with different orientations for the a-axis or b-axis (rotated around the c-axis). Physical semiconductor (CAAC-OS:C Axis Aligned Crystalline It may also be called an oxide semiconductor.

[0102] CAAC-OS, in a broad sense, is a non-single crystal that, when viewed from a direction perpendicular to its ab-plane, has three characteristics. It has an atomic arrangement of squares, hexagons, equilateral triangles, or regular hexagons, and is perpendicular to the c-axis direction. Looking at it, an oxide containing a phase in which metal atoms are arranged in layers, or in which metal atoms and oxygen atoms are arranged in layers. say.

[0103] CAAC-OS is not a single crystal, but it is not formed solely from amorphous material either. CAAC contains crystalline parts (crystalline portions), but the boundary between one crystalline portion and another crystalline portion is not clear. Sometimes it is difficult to clearly distinguish boundaries.

[0104] Some of the oxygen in CAAC-OS may be replaced with nitrogen. The c-axis of each individual crystal portion that makes up the structure is in a specific direction (for example, the group on which CAAC-OS is formed). They may be aligned perpendicular to the surface of the board, the surface of CAAC-OS, etc. Alternatively, CAAC -The normals of the ab-planes of the individual crystal parts that make up the OS are in a specific direction (for example, CAAC-OS) It may be oriented perpendicular to the substrate surface on which it is formed, the surface of CAAC-OS, etc.

[0105] CAAC-OS can be a conductor, a semiconductor, or an insulator, depending on its composition. And so on. Also, depending on its composition, it may be transparent to visible light, They may not have it.

[0106] Examples of such CAAC-OS include those that form in a film-like manner, and those that form on the film surface or the base on which the film is formed. When observed from a direction perpendicular to the plate surface, a triangular or hexagonal atomic arrangement is observed, and the film When the cross-section is observed, a layered arrangement of metal atoms or metal atoms and oxygen atoms (or nitrogen atoms) is found. It is also possible to list the recognized oxides.

[0107] An example of the crystal structure contained in CAAC-OS is explained in detail using Figures 14 to 16. In addition, unless otherwise specified, in Figures 14 to 16, the upward direction is the c-axis direction. Let the plane perpendicular to it be called plane ab. Note that when we simply refer to the upper half and the lower half, we mean the plane with plane ab as the boundary. This refers to the upper and lower halves of a case. Also, in Figure 14, the circled O represents O in 4-coordinate. The O enclosed in a double circle indicates a 3-coordinate O.

[0108] Figure 14(A) shows one 6-coordinate In atom and six 4-coordinate oxygen atoms adjacent to the In atom (hereinafter referred to as 4 The structure shows a coordinated O) and a nearby oxygen atom. Here, for each metal atom, A structure showing only the children is called a small group. The structure in Figure 14(A) takes the form of an octahedron, but For simplicity, it is shown as a planar structure. Note that the upper and lower halves of Figure 14(A) are respectively There are 4-coordinate oxygen atoms, 3 in each group. The small group shown in Figure 14(A) has a charge of 0.

[0109] Figure 14(B) shows one 5-coordinate Ga atom and three 3-coordinate oxygen atoms adjacent to the Ga atom (hereinafter referred to as 3 The structure shows a coordinated oxygen atom and two 4-coordinate oxygen atoms adjacent to Ga. The 3-coordinate oxygen atom is All of them are located on the ab plane. There is one in the upper half and one in the lower half of Figure 14(B), for a total of four. There is a coordinate oxygen atom. Also, since In can take on a 5-coordinate state, it can take on the structure shown in Figure 14(B). The small group shown in Figure 14(B) has a charge of 0.

[0110] Figure 14(C) shows a structure having one 4-coordinate Zn and four 4-coordinate O adjacent to the Zn. The structure is shown. The upper half of Figure 14(C) has one 4-coordinate oxygen atom, and the lower half has three 4-coordinate oxygen atoms. There is an O. Or, there are three 4 - coordinated Os in the upper half of FIG. 14(C) and one 4 - coordinated O in the lower half may be present. The small group shown in FIG. 14(C) has a charge of 0.

[0111] FIG. 14(D) shows a structure having one 6 - coordinated Sn and six 4 - coordinated Os adjacent to the Sn. There are three 4 - coordinated Os in the upper half of FIG. 14(D) and three 4 - coordinated Os in the lower half. The small group shown in FIG. 14(D) has a charge of +1.

[0112] FIG. 14(E) shows a small group containing two Zn. There is one 4 - coordinated O in the upper half of FIG. 14(E) and one 4 - coordinated O in the lower half. The small group shown in FIG. 14(E) has a charge of -1.

[0113] Here, an aggregate of a plurality of small groups is called a medium group, and an aggregate of a plurality of medium groups is called a large group (also referred to as a unit cell).

[0114] Here, the rule for the combination of these small groups will be described. The three Os in the upper half of the 6 - coordinated In shown in FIG. 14(A) each have three adjacent Ins downward, and the three Os in the lower half each have three adjacent Ins upward. The one O in the upper half of the 5 - coordinated Ga shown in FIG. 14(B) has one adjacent Ga downward, and the one O in the lower half has one adjacent Ga upward. The one O in the upper half of the 4 - coordinated Zn shown in FIG. 14(C) has one adjacent Zn downward, and the three Os in the lower half each have three adjacent Zns upward. Thus, the number of 4 - coordinated Os above the metal atom is equal to the number of adjacent metal atoms below that O, and similarly, the number of 4 - coordinated Os below the metal atom is equal to the number of adjacent metal atoms above that O. ​​​​The number of contacting metal atoms is equal. Since O is 4-coordinate, the number of adjacent metal atoms in the downward direction and the number in the upward direction are equal. The sum of the number of neighboring metal atoms in a given position is 4. Therefore, the 4-coordinate oxygen atoms above the metal atom When the sum of the number of atoms and the number of 4-coordinate oxygen atoms below another metal atom is 4, the atom has a metal atom. Two types of small groups can bond with each other. For example, a 6-coordinate metal atom (In) When Sn) is bonded via the lower half of the 4-coordinate oxygen atoms, there are 3 4-coordinate oxygen atoms, so 5 It can bond with either a coordinating metal atom (Ga or In) or a four-coordinating metal atom (Zn). It will become that.

[0115] Metal atoms with these coordination numbers are bonded in the c-axis direction via 4-coordinate oxygen atoms. In addition, multiple small groups combine such that the total charge of the layered structure becomes 0. It forms a middle group.

[0116] Figure 15(A) shows a model diagram of the intermediate groups that constitute the layer structure of In-Sn-Zn oxides. Figure 15(B) shows the large group, which is composed of three medium groups. (C) shows the atomic arrangement when the layer structure of Figure 15(B) is observed from the c-axis direction.

[0117] In Figure 15(A), for simplicity, three-coordinate oxygen atoms are omitted, and only the number of four-coordinate oxygen atoms is shown. For example, the upper and lower halves of Sn each contain three 4-coordinate oxygen atoms (indicated by the circle). It is shown as 3. Similarly, in Figure 15(A), the upper half and lower half of In are Each of these has one 4-coordinate oxygen atoms, which are shown as "1" in the circle. Similarly, Figure 15 In (A), the lower half has one 4-coordinate oxygen atom, and the upper half has three 4-coordinate oxygen atoms. Zn has one 4-coordinate oxygen atom in the upper half and three 4-coordinate oxygen atoms in the lower half. This indicates that.

[0118] In Figure 15(A), the middle group constituting the layer structure of the In-Sn-Zn oxide is the upper Starting from there, there are three 4-coordinate oxygen atoms in the upper half and three 4-coordinate oxygen atoms in the lower half of the Sn atom, and one 4-coordinate oxygen atom in each half. It is bonded to In in the upper and lower halves, and that In has three 4-coordinate oxygen atoms in the upper half. It is bonded to Zn, and through one 4-coordinate oxygen atom in the lower half of the Zn, three 4-coordinate oxygen atoms are bonded to the upper half. In is bonded to the In in the lower half, and that In has one 4-coordinate O in the upper half of the Zn It binds to a small group consisting of two atoms, via one 4-coordinate oxygen atom in the lower half of this small group. This configuration consists of 4-coordinate oxygen atoms bonded to Sn atoms in the upper and lower halves, with three oxygen atoms bonded to each other. Multiple groups combine to form a larger group.

[0119] Here, for 3-coordinate oxygen and 4-coordinate oxygen, the charge per bond is -0.6, respectively. 67, -0.5 can be considered. For example, In (6-coordinate or 5-coordinate), Zn (4 The charges of (5-coordinate) and Sn (5-coordinate or 6-coordinate) are +3, +2, and +4, respectively. Therefore Therefore, the small group containing Sn has a charge of +1. As a result, it forms a layered structure containing Sn. For this to work, a charge of -1 is needed to cancel out the charge of +1. Figure 1 shows a structure that takes on a charge of -1. As shown in 4(E), a small group containing two Zn elements is an example. If there is one small group and one small group containing two Zn atoms, the charges cancel each other out. Therefore, the total charge of the layered structure can be set to 0.

[0120] Specifically, by repeating the large group shown in Fig. 15(B), the crystal of In-Sn-Zn system oxide (In2SnZn3O8) can be obtained. The obtained In-S n-Zn system oxide layer structure can be represented by the composition formula In2SnZn2O7(ZnO) m (m is 0 or a natural number .).

[0121] In addition, there are also quaternary metal oxides such as In-Sn-Ga-Zn system oxides, and ternary metal oxides such as In-Ga-Zn system oxides (also denoted as IGZO), In- Al-Zn system oxides, Sn-Ga-Zn system oxides, Al-Ga-Zn system oxides, Sn-A l-Zn system oxides, In-Hf-Zn system oxides, In-La-Zn system oxides, In-C e-Zn system oxides, In-Pr-Zn system oxides, In-Nd-Zn system oxides, In-Sm -Zn system oxides, In-Eu-Zn system oxides, In-Gd-Zn system oxides, In-Tb- Zn system oxides, In-Dy-Zn system oxides, In-Ho-Zn system oxides, In-Er-Z n system oxides, In-Tm-Zn system oxides, In-Yb-Zn system oxides, In-Lu-Zn system oxides, and binary metal oxides such as In-Zn system oxides, Sn-Zn system oxides, Al -Zn system oxides, Zn-Mg system oxides, Sn-Mg system oxides, In-Mg system oxides, and I n-Ga system oxide materials, etc. are the same when used.

[0122] For example, Fig. 16(A) shows a model diagram of the middle group constituting the layer structure of In-Ga-Zn system oxide. .

[0123] In Fig. 16(A), the middle group constituting the layer structure of In-Ga-Zn system oxide is the upper In order from there, the ion has three 4-coordinate oxygen atoms in the upper half and three in the lower half, and one 4-coordinate oxygen atom in the upper half. It bonds with Zn in the middle, and via the three 4-coordinate oxygen atoms in the lower half of that Zn, the 4-coordinate oxygen atoms are connected. Each atom bonds with the Ga atoms in the upper and lower halves, and one of the four-coordinate O atoms in the lower half of that Ga atom... Through this, the structure consists of three 4-coordinate oxygen atoms bonded to the in atoms in the upper and lower halves, respectively. These smaller groups combine to form larger groups.

[0124] Figure 16(B) shows the large group, which is composed of three medium groups. Figure 16(C) is Figure 16(B) shows the atomic arrangement when the layered structure is observed from the c-axis direction.

[0125] Here, the charges of In (6-coordinate or 5-coordinate), Zn (4-coordinate), and Ga (5-coordinate) are as follows: Since they are +3, +2, and +3 respectively, small groups containing any of In, Zn, and Ga Therefore, the charge becomes 0. The charge of the sum is always 0.

[0126] Furthermore, the intermediate groups constituting the layer structure of the In-Ga-Zn oxide are shown in Figure 16(A). Not limited to the same intermediate group, but combining intermediate groups with different arrangements of In, Ga, and Zn. Large groups could also be targeted.

[0127] Specifically, the large groups shown in Figure 16(B) are repeated, resulting in In-Ga-Zn Crystals of the In-Ga-Zn system oxide can be obtained. The layer structure of the obtained In-Ga-Zn system oxide is also shown. InGaO3(ZnO) n It can be expressed by the empirical formula (where n is a natural number).

[0128] This embodiment can be implemented in combination with other embodiments.

[0129] (Embodiment 3) In one aspect of the present invention, a light-emitting device comprises a light-emitting element that emits monochromatic light such as white, and a color-emitting element. It employs a color filter method that displays full-color images by combining filters. This can be done. Alternatively, by using multiple light-emitting elements that emit light of different hues, A method for displaying multicolor images can also be adopted. This method utilizes the light-emitting element The EL layer provided between a pair of electrodes is painted with different colors according to the corresponding color, and the painting method is I was called.

[0130] In the case of the paint separation method, the EL layer is usually painted using a mask such as a metal mask. This is done using a vapor deposition method. Therefore, the size of the pixels depends on the precision of the EL layer coating achieved by the vapor deposition method. On the other hand, in the case of the color filter method, unlike the paint separation method, the paint separation of the EL layer is It is not necessary to do so. Therefore, it is easier to reduce the pixel size than with the color-coding method. This enables the realization of high-resolution pixels.

[0131] Furthermore, the light-emitting device emits light from the light-emitting element from the substrate on which the transistor is formed, the so-called element substrate side. A bottom emission structure extracts light from the light-emitting element from the side opposite the element substrate. There is a top emission structure. In the case of a top emission structure, the light emitted from the light-emitting element... The light is not obstructed by various elements such as wiring, transistors, and capacitance. Therefore, compared to a bottom emission structure, it is possible to improve the efficiency of light extraction from the pixels. Therefore, the top emission structure allows for low current supply to the light-emitting element. Because high brightness can be obtained, it is advantageous for extending the lifespan of light-emitting elements.

[0132] Furthermore, in a light-emitting device according to one aspect of the present invention, the light emitted from the EL layer is resonated within the light-emitting element. It may have a microcavity (micro-optical resonator) structure. The T-structure allows for increased extraction efficiency from light-emitting elements for specific wavelengths. Therefore, it is possible to improve the brightness and color purity of the pixel area.

[0133] Figure 10 shows an example of a cross-sectional view of a pixel. Note that in Figure 10, the cross-section of the pixel corresponding to red is shown. The image shows a portion of the surface, a portion of the cross-section of a pixel corresponding to blue, and a portion of the cross-section of a pixel corresponding to green. Yes, they are.

[0134] Specifically, in Figure 10, there is pixel 140r corresponding to red, pixel 140g corresponding to green, and blue The corresponding pixel 140b is shown. Pixel 140r, pixel 140g, pixel 140b Each has anode 715r, anode 715g, and anode 715b, respectively. The above anode 715r, Anode 715g and Anode 715b correspond to pixels 140r, 140g, and 140b, respectively. In this configuration, it is provided on top of the insulating film 750 formed on the substrate 740.

[0135] Furthermore, a partition wall 73 having an insulating film is placed on anode 715r, anode 715g, and anode 715b. 0 is provided. Partition wall 730 has an opening, and in the opening, anode 715r, Anode 715g and anode 715b are partially exposed. To cover the area, an EL layer 731 and a transparent material for visible light are placed on the partition wall 730. The cathode 732 and the other elements are stacked in sequence.

[0136] The area where the anode 715r, the EL layer 731, and the cathode 732 overlap is the light-emitting element corresponding to red. This corresponds to 741r. The area where the anode 715g, the EL layer 731, and the cathode 732 overlap is This corresponds to the light-emitting element 741g which is green. Anode 715b, EL layer 731, cathode 73 The overlapping portion with 2 corresponds to the light-emitting element 741b, which is blue.

[0137] Furthermore, the substrate 742 is positioned between the light-emitting element 741r, the light-emitting element 741g, and the light-emitting element 741b. It is positioned between the substrate 740 and the substrate 742. On substrate 742, there is a corresponding to pixel 140r. Coloring layer 743r, corresponding to pixel 140g; Coloring layer 743g, corresponding to pixel 140b. A layer 743b is provided. The colored layer 743r has a transmittance of light in the wavelength region corresponding to red. The colored layer 743g has a higher transmittance of light in other wavelength regions, and the colored layer 743g has a higher transmittance of light in the wavelength region corresponding to green. The light transmittance in this region is higher than that of light in other wavelength regions, and the colored layer 743b is blue. This layer has a higher transmittance of light in the corresponding wavelength range than the transmittance of light in other wavelength ranges.

[0138] Furthermore, the substrate 742 is covered with a colored layer 743r, a colored layer 743g, and a colored layer 743b. An overcoat 744 is provided. The overcoat 744 is a colored layer 743 r, a transparent material to visible light for protecting the colored layer 743g and colored layer 743b. It is preferable to use a resin material that is a layer and has high flatness. Colored layer 743r, colored layer 743 g, and the colored layer 743b, along with the overcoat 744, are considered together as a color filter. Alternatively, you can color each of the colored layers 743r, 743g, and 743b. It can be considered a filter.

[0139] In Figure 10, the anode 715r has a conductive film 745r with high visible light reflectivity, and visible light A conductive film 746r, whose transmittance is higher than that of the conductive film 745r, is used in sequence by laminating it. Furthermore, the anode 715g is coated with a conductive film 745g with high visible light reflectivity, and the transmittance of visible light is as described above. A conductive film with a higher conductivity of 746g is used by sequentially laminating it with a conductive film with a conductivity of 745g. The thickness shall be less than the thickness of the conductive film 746r. Also, visible light shall be applied to the anode 715b. A conductive film 745b with high reflectivity is used.

[0140] Therefore, in the light-emitting device shown in Figure 10, the light-emitting element 741r emits light from the EL layer 731. The optical path length of the emitted light can be adjusted by the distance between the conductive film 745r and the cathode 732. Furthermore, in the light-emitting element 741g, the optical path length of the light emitted from the EL layer 731 is the conductive film 7 The distance between 45g and cathode 732 can be adjusted. Also, the light-emitting element 741b The optical path length of the light emitted from the EL layer 731 depends on the distance between the conductive film 745b and the cathode 732. It can be adjusted.

[0141] In one aspect of the present invention, a light-emitting element 741r, a light-emitting element 741g, and a light-emitting element 741b are provided together. By adjusting the optical path length according to the corresponding wavelength of light, the EL layer 731 emits This can also be used as a microcavity structure that causes the emitted light to resonate within each of the above-mentioned light-emitting elements. stomach.

[0142] By employing the above microcavity structure in a light-emitting device according to one aspect of the present invention, In the light emitted from element 741r, the intensity of the light having a wavelength corresponding to red is at resonance. This increases the color purity and brightness of the red light obtained through the colored layer 743r. Furthermore, in the light emitted from the light-emitting element 741g, the intensity of light having a wavelength corresponding to green The degree increases due to resonance. Therefore, the color purity of the green light obtained through the colored layer 743g and Brightness increases. Also, in the light emitted from the light-emitting element 741b, the wavelength corresponding to blue is The intensity of the light it possesses increases due to resonance. Therefore, the blue light obtained through the colored layer 743b The color purity and brightness are enhanced.

[0143] Note that Figure 10 shows a configuration using pixels corresponding to three colors: red, green, and blue. In one aspect of the invention, the configuration is not limited to that. The color combination used in one aspect of the invention is For example, using four colors: red, green, blue, and yellow, or three colors: cyan, magenta, and yellow. It is acceptable to include them. Alternatively, the above color combinations include light red, green, and blue, as well as dark red. You may also use six colors: green, blue, and red. Alternatively, the above color combinations may include red, green, blue, and blue. You may also use six colors: um, magenta, yellow, and red.

[0144] For example, the colors that can be represented using red, green, and blue pixels are represented by the respective pixels on the chromaticity diagram. It is limited to the colors shown inside the triangle formed by the three points corresponding to the light color. Therefore, red, green, blue, When a yellow pixel is used, the emitted color of a light-emitting element exists outside the triangle on the chromaticity diagram. By adding this separately, the color gamut that can be expressed by the light-emitting device is expanded, enriching color reproduction. It is possible.

[0145] Furthermore, in Figure 10, among the light-emitting element 741r, light-emitting element 741g, and light-emitting element 741b, In the light-emitting element 741b with the shortest wavelength λ, the conductive film 745b with high reflectivity of visible light is used. When used as an anode, the film thickness of the other light-emitting elements 741r and 741g differs from that of the other elements. The optical path length is adjusted by using conductive films 746r and 746g. In one aspect of the invention, even in the light-emitting element 741b with the shortest wavelength λ, the reflectivity of visible light is high. On the conductive film 745b, conductive films such as conductive film 746r and conductive film 746g have a visible light transmittance. A highly conductive film may be provided. However, as shown in Figure 10, the light-emitting element with the shortest wavelength λ In child 741b, when the anode is made of a conductive film 745b with high visible light reflectivity, all In a light-emitting element, the anode is made more efficient than when a conductive film with high visible light transmittance is used for the anode. This is preferable because it simplifies the manufacturing process.

[0146] Furthermore, conductive film 745b, which has a high reflectivity of visible light, and conductive film 746r, which has a high transmittance of visible light. Compared to conductive film 746g, the work function is often smaller. Therefore, the wavelength of light λ is shortest. In the light-emitting element 741b, compared to the light-emitting elements 741r and 741g, the anode 715b Because hole injection into the EL layer 731 is difficult, the luminous efficiency tends to be low. In one aspect of the present invention, in the light-emitting element 741b with the shortest wavelength λ of light, the EL layer 731 Among these, in the layer in contact with the conductive film 745b, which has a high reflectivity of visible light, a material with high hole transport properties. The substance contains a material that exhibits acceptor properties (electron-accepting properties) for the material with high hole transport capabilities. It is preferable to use a composite material having the properties described above. The composite material is formed in contact with the anode 715b. This facilitates hole injection from the anode 715b to the EL layer 731, resulting in light emission. This can increase the luminous efficiency of element 741b.

[0147] Substances that exhibit acceptor properties include 7,7,8,8-tetracyano-2,3,5,6- Examples include tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, etc. It is possible. Furthermore, transition metal oxides can be cited. Also, in the periodic table, Group 4 elements Examples include oxides of metals belonging to Group 8. Specifically, vanadium oxide, acid Niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide Rhenium oxide is preferred because of its high acceptability. In particular, molybdenum oxide is It is preferable because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle.

[0148] Examples of highly hole-transporting materials used in composite materials include aromatic amine compounds and carbazole derivatives. Conductors, aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, polymers, etc.), Various compounds can be used. Note that the organic compounds used in the composite material include holes. It is preferable that the organic compound has high transportability. Specifically, 10 -6 cm 2 / Vs or more It is preferable that the material has a hole mobility of . However, it is preferable that the material has a higher hole transport capability than electron transport. Other materials may also be used.

[0149] Furthermore, conductive films 745r, 745g, and 745b, which have high reflectivity of visible light, are also considered. For example, aluminum, silver, or alloys containing these metallic materials, etc., in a single layer, or It can be formed by lamination. Also, conductive film 745r, conductive film 745g, The conductive film 745b consists of a conductive film with high reflectivity of visible light and a thin conductive film (preferably 20n They may be formed by stacking (m or less, more preferably 10 nm or less). For example, visible A thin titanium film or molybdenum film is laminated onto a conductive film with high light reflectivity to create conductive film 745b. By forming a conductive film with high visible light reflectivity (aluminum, aluminum-containing This can prevent the formation of an oxide film on the surface of alloys (such as silver).

[0150] Furthermore, conductive films 746r and 746g, which have high visible light transmittance, contain, for example, 100% nitrile oxide. The following are used: zinc, tin oxide, zinc oxide, indium tin oxide, indium zinc oxide, etc. It is possible.

[0151] Furthermore, the cathode 732 is, for example, a thin conductive film that transmits light (preferably 20 nm or less). More preferably, a conductive film composed of a conductive metal oxide is laminated with a film of 10 nm or less. This can be formed by [doing something]. A thin conductive film that transmits light can be made of silver, magnesium or alloys containing these metallic materials can be formed in a single layer or in layers. Examples of conductive metal oxides include indium oxide, tin oxide, zinc oxide, and indium tin oxide. Oxides, indium zinc oxide, or these metal oxide materials containing silicon oxide You can use the one that you have.

[0152] This embodiment can be implemented in appropriate combination with other embodiments.

[0153] (Embodiment 4) In this embodiment, a bottom emission structure, a top emission structure, and a dual emission Let's explain the dual emission structure. A dual emission structure is a structure that emits light from a light-emitting element into the element base This refers to a structure that allows extraction from both the plate side and the side opposite the element substrate.

[0154] Figure 11(A) shows the case where the light emitted from the light-emitting element 6033 is extracted from the anode 6034 side. The image shows a cross-sectional view of the pixel. Transistor 6031 is covered with insulating film 6037, providing insulation. A partition wall 6038 having an opening is formed on the membrane 6037. In this, the anode 6034 is partially exposed, and in this opening, the anode 6034 and the EL layer 60 35, cathode 6036 are stacked in order.

[0155] The anode 6034 is formed of a material or film thickness that easily transmits light, and the cathode 6036 is light-transmitting Formed with a material or film thickness that is difficult to work with. With the above configuration, a white arrow is visible from the anode 6034 side. As shown, a bottom emission structure that extracts light can be obtained.

[0156] Figure 11(B) shows the case where the light emitted from the light-emitting element 6043 is extracted from the cathode 6046 side. The image shows a cross-sectional view of the pixel. Transistor 6041 is covered with insulating film 6047, providing insulation. A partition wall 6048 having an opening is formed on the membrane 6047. In this, the anode 6044 is partially exposed, and in this opening, the anode 6044 and the EL layer 60 45 and cathode 6046 are stacked in order.

[0157] The anode 6044 is formed of a material or film thickness that does not transmit light easily, and the cathode 6046 transmits light. Formed with an easily formed material or film thickness. With the above configuration, a white arrow is visible from the cathode 6046 side. As shown, a top-emission structure that extracts light can be obtained.

[0158] Figure 11(C) shows the light emitted from the optical element 6053 on the anode 6054 side and the cathode 6056 side. This shows a cross-sectional view of a pixel when extracted from the image. Transistor 6051 is covered with insulating film 6057. The insulating film 6057 is divided, and a partition wall 6058 having an opening is formed on it. In the opening of 6058, the anode 6054 is partially exposed, and in the opening, the anode 60 54, the EL layer 6055, and the cathode 6056 are stacked in that order.

[0159] The anode 6054 and cathode 6056 are formed from a material or film thickness that easily transmits light. As a result, light is extracted from the anode 6054 and cathode 6056 sides as indicated by the white arrows. This allows for the creation of a dual-emission structure.

[0160] The electrodes that will serve as the anode or cathode may be metals, alloys, electrically conductive compounds, and these materials. Mixtures can be used. Specifically, indium oxide-tin oxide (ITO:I Indium Tin Oxide), silicon or silicon oxide containing indium oxide Tin oxide, indium zinc oxide, t Indium oxide containing sten and zinc oxide, gold (Au), platinum (Pt), nickel Ni (Ni), Tungsten (W), Chromium (Cr), Molybdenum (Mo), Iron (Fe), In addition to cobalt (Co), copper (Cu), palladium (Pd), and titanium (Ti), the periodic table of elements Elements belonging to Group 1 or Group 2, such as lithium (Li) and cesium (Cs). Alkali metals, and alkaline earth metals such as calcium (Ca) and strontium (Sr). The group, magnesium (Mg), and alloys containing them (MgAg, AlLi), Europ Rare earth metals such as um (Eu) and ytterbium (Yb), and alloys containing these, and others. Graphene and the like can be used. Then, the above materials can be appropriately selected and the film thickness can be optimized. By setting it to a certain value, you can create a bottom emission structure, a top emission structure, or a dual emission structure. It becomes possible to create different types of emission structures.

[0161] This embodiment can be implemented in appropriate combination with other embodiments.

[0162] (Embodiment 5) Figure 12 is an example of a perspective view of a light-emitting device according to one aspect of the present invention.

[0163] The light-emitting device shown in Figure 12 consists of a panel 1601, a circuit board 1602, and a connection part 1603. It has. Panel 1601 has a pixel section 1604 which has multiple pixels, and multiple pixels A scan line drive circuit 1605 selects each row, and inputs the image signal to the pixels within the selected row. It has a signal line drive circuit 1606 that controls the scan line drive circuit 1605. Specifically, the scan line drive circuit 1605 It generates signals to be input to wiring G1 to wiring G3.

[0164] From the circuit board 1602, various signals and the power supply potential are transmitted via the connection part 1603 to the panel. Input is sent to 1601. Connection part 1603 is FPC (Flexible Printer). d Circuit) etc. can be used. Also, COF tape can be used on connection part 1603. When using this method, some circuits within the circuit board 1602, or the scan lines of the panel 1601 The drive circuit 1605 and part of the signal line drive circuit 1606 are formed on a separately prepared chip. Next, the chip is connected to the COF tape using the COF (Chip On Film) method. You can do that.

[0165] This embodiment can be implemented in combination with other embodiments.

[0166] (Embodiment 6) A light-emitting device according to one aspect of the present invention comprises a display device, a personal computer, and a recording medium. Image playback devices (typically DVDs: Digital Versatile Discs, etc.) It can be used in a device that has a display capable of playing back a recording medium and displaying its image. Yes, it is possible. In addition, as electronic devices that can use the light-emitting device according to one aspect of the present invention, Mobile phones, game consoles including portable devices, personal digital assistants, e-books, video cameras, digital Still camera, goggle-type display (head-mounted display), navigation Audio systems, sound reproduction equipment (car audio, digital audio players, etc.), copying Machines, fax machines, printers, multifunction printers, automated teller machines (ATMs) Examples include vending machines. Specific examples of these electronic devices are shown in Figure 13.

[0167] Figure 13(A) shows a portable game console, comprising a casing 5001, casing 5002, display unit 5003, Display unit 5004, microphone 5005, speaker 5006, operation keys 5007, stand It has illustration 5008, etc. A light-emitting device according to one aspect of the present invention has a display unit 5003, a display unit It can be used in 5004. Display unit 5003 or display unit 5004 in one aspect of the present invention By using the light-emitting device described herein, a high-definition portable game console can be provided. The portable game console shown in Figure 13(A) has two display units 5003 and 5004. While they may have them, the number of display units a portable game console may have is not limited to these.

[0168] Figure 13(B) shows a display device, which includes a housing 5201, a display unit 5202, a support base 5203, etc. The light-emitting device according to one aspect of the present invention can be used in the display unit 5202. By using a light-emitting device according to one aspect of the present invention in 5202, a high-resolution display device is provided. It is possible. Furthermore, the display devices include those for personal computers, TV broadcast reception, and advertising. This includes all information display devices, such as those used for signage.

[0169] Figure 13(C) shows a notebook personal computer, consisting of a casing 5401 and a display unit 5402. The present invention includes a keyboard 5403, a pointing device 5404, and the like. The light-emitting device can be used in the display unit 5402. By using a light-emitting device related to this, a high-resolution notebook personal computer is provided. It is possible.

[0170] Figure 13(D) shows a portable information terminal, consisting of a housing 5601, a display unit 5602, and operation keys 5603. It has the following features. The portable information terminal shown in Figure 13(D) has the modem built into the casing 5601. It may also be used. A light-emitting device according to one aspect of the present invention can be used in the display unit 5602. By using a light-emitting device according to one aspect of the present invention in the display unit 5602, a high-resolution portable information terminal can be created. It can be provided.

[0171] Figure 13(E) is a mobile phone, consisting of a housing 5801, a display unit 5802, an audio input unit 5803, It has an audio output unit 5804, an operation key 5805, a light receiving unit 5806, etc. By converting the light received into an electrical signal, external images can be captured. A light-emitting device according to one aspect of the invention can be used in the display unit 5802. By using a light-emitting device according to one aspect of the present invention, it is possible to provide a high-definition mobile phone. Cut.

[0172] This embodiment can be implemented in appropriate combination with other embodiments.

[0173] (Embodiment 7) In this embodiment, the operation of pixel 100 shown in Figure 1(A), as described in Embodiment 1, The value of the gate voltage Vgs of transistor 11 during period 3 was determined by simulation. I sought it.

[0174] The simulation is performed under conditions A or condition B, where the potential V0 values ​​in the wiring IL are different from each other. The procedure was performed using B. Specifically, the potential values ​​of each wire under conditions A and B are shown in Table 1 below. As shown, the potential GVDD is the high voltage applied to wiring G1, wiring G2, and wiring G3, respectively. This corresponds to the potential of the level. Furthermore, the potential GVSS is applied to wiring G1, wiring G2, and wiring G3. Each corresponds to a given low-level potential. Note that in Table 1, the potential Vcat is set to 0V. The values ​​of potentials Vdata, Vano, V0, GVDD, and GVSS are as follows: It is shown as the potential difference with respect to potential Vcat.

[0175] [Table 1]

[0176] Furthermore, the ratio of the channel length L to the channel width W of each transistor in the simulation is: For transistor 11, L / W = 9μm / 3μm, and for transistors 12 through 15... Then, L / W = 3μm / 3μm. And the total of the pixels 100 shown in Figure 1(A) In a transistor, a conductive film and a semiconductor film function as either a source or a drain. If we call the adjacent region region A, then the region where the gate electrode is formed is The length (Lov) in the channel length direction in the overlapping region was set to 1.5 μm.

[0177] During period 3, the gate voltage Vgs of transistor 11 is as shown in Figure 3(C), The pressure becomes Vdata - V0 + Vth. Therefore, in pixel 100 shown in Figure 1(A), Since Vgs-Vth=Vdata-V0, ideally Vgs-Vth is the threshold voltage. It has a constant value regardless of the pressure Vth value.

[0178] Figure 17 shows the Vgs-Vt obtained by simulation when condition A is used. The value of h is shown. In Figure 17, the horizontal axis is the threshold voltage Vth (V), and the vertical axis is Vgs-Vth (V). The value is shown. In Figure 17, even when the threshold voltage Vth is changed, the value of Vgs-Vth remains constant. It can be seen that the results are fairly uniform, with the variation being kept to around 25% to 30%.

[0179] Figure 18 shows the Vgs-Vt obtained by simulation when using condition B. The value of h is shown. In Figure 18, the horizontal axis is the threshold voltage Vth (V), and the vertical axis is Vgs-Vth (V). The value is shown. In Figure 18, when the threshold voltage Vth has a positive value, Vgs-Vt The value of h is uniform. However, if the value of the threshold voltage Vth is negative, the threshold voltage Vt As the value of h increases in the negative direction, the value of Vgs-Vth increases, and Vgs- It can be seen that the value of Vth depends on the threshold voltage Vth.

[0180] From the results of the above simulation, in the light-emitting device according to one aspect of the present invention, transistor 1 Even if 1 is a normal onion, that is, even if the threshold voltage Vth has a negative value, The gate of transistor 11 is set to a value that takes into account the threshold voltage Vth of transistor 11. It was proven that the voltage Vgs can be set.

[0181] This embodiment can be implemented in combination with other embodiments. [Explanation of symbols]

[0182] 11 transistors 12 transistors 13 transistors 14 transistors 15 transistors 16 Capacitive elements 17 Light-emitting element 100 pixels 140b pixels 140g pixels 140r pixels 715b Anode 715g anode 715r anode 730 Bulkhead 731 EL layer 732 Cathode 740 circuit boards 741b Light-emitting element 741g light-emitting element 741r light-emitting element 742 circuit boards 743b Colored layer 743g colored layer 743r colored layer 744 Overcoat 745b Conductive film 745g conductive film 745r conductive film 746g conductive film 746r conductive film 750 insulating film 800 circuit boards 801 Conductive film 802 Gate Insulator 803 Semiconductor film 804 Conductive film 805 Conductive film 806 Semiconductor film 807 Conductive film 808 Conductive film 809 Conductive film 810 Conductive film 811 Semiconductor film 812 Conductive film 813 Semiconductor film 814 Conductive film 815 Conductive film 816 Conductive film 817 Semiconductor film 818 Conductive film 819 Conductive film 820 Insulating film 821 Insulating film 822 Conductive film 823 Contact Hole 824 Insulating film 825 EL layer 826 Conductive film 900 circuit boards 901 Semiconductor film 902 Gate Insulator 903 Conductive film 904 Conductive film 905 Conductive film 906 Semiconductor film 907 Conductive film 908 Conductive film 909 Conductive film 911 Conductive film 912 Semiconductor film 913 Conductive film 914 Conductive film 915 Conductive film 916 Conductive film 917 Conductive film 920 Insulating film 921 Conductive film 922 Contact Holes 923 Insulating film 924 EL layer 925 Conductive film 1601 Panel 1602 Circuit board 1603 Connection part 1604 pixel section 1605 Scan Line Drive Circuit 1606 Signal Line Drive Circuit 5001 enclosure 5002 enclosure 5003 Display section 5004 Display section 5005 Microphone 5006 Speaker 5007 Operation Keys 5008 Stylus 5201 enclosure 5202 Display section 5203 Support stand 5401 enclosure 5402 Display section 5403 Keyboard 5404 Pointing device 5601 enclosure 5602 Display section 5603 Operation Keys 5801 enclosure 5802 Display section 5803 Voice Input Section 5804 Audio output section 5805 Operation Keys 5806 Light receiving section 6031 transistor 6033 Light-emitting element 6034 Anode 6035 EL layer 6036 Cathode 6037 Insulating film 6038 Bulkhead 6041 transistor 6043 Light-emitting element 6044 Anode 6045 EL layer 6046 Cathode 6047 Insulating film 6048 Bulkhead 6051 Transistor 6053 Optical element 6054 Anode 6055 EL layer 6056 Cathode 6057 Insulating film 6058 next door

Claims

1. It has multiple pixels in the pixel area, At least one of the plurality of pixels has a first transistor to a fifth transistor and a light-emitting element. The first transistor has the function of controlling the input of an image signal to the first pixel, The source or drain of the second transistor is always in electrical contact with the source or drain of the fifth transistor. Either the source or drain of the third transistor is always in contact with the gate of the second transistor. The third transistor has the function of inputting a potential corresponding to the image signal to the gate of the second transistor via the channel formation region of the third transistor. Either the source or drain of the fourth transistor is always in contact with the gate of the second transistor. The source or drain of the fourth transistor is always in electrical contact with the first wiring. The source or drain of the fifth transistor is always in electrical contact with the pixel electrode of the light-emitting element. When the second wiring is electrically connected to the pixel electrode of the light-emitting element via at least the channel formation region of the second transistor and the channel formation region of the fifth transistor, the second transistor and the fifth transistor are both turned on. The second transistor is a light-emitting device having the function of controlling the current supplied to the light-emitting element according to the potential, A first semiconductor film having a channel formation region for the second transistor and a channel formation region for the fifth transistor, A second semiconductor film having a channel formation region for the third transistor, A first conductive film having a region positioned above the first semiconductor film and functioning as the gate of the second transistor, A second conductive film having a region positioned above the first semiconductor film and functioning as the gate of the fifth transistor, A third conductive film having a region positioned above the second semiconductor film and functioning as the gate of the third transistor, The first semiconductor film has a curved shape in the channel formation region of the second transistor. Light-emitting device.

2. It has multiple pixels in the pixel area, At least one of the plurality of pixels has a first transistor to a fifth transistor and a light-emitting element. The first transistor has the function of controlling the input of an image signal to the first pixel, The source or drain of the second transistor is always in electrical contact with the source or drain of the fifth transistor. Either the source or drain of the third transistor is always in contact with the gate of the second transistor. The third transistor has the function of inputting a potential corresponding to the image signal to the gate of the second transistor via the channel formation region of the third transistor. Either the source or drain of the fourth transistor is always in contact with the gate of the second transistor. The source or drain of the fourth transistor is always in electrical contact with the first wiring. The source or drain of the fifth transistor is always in electrical contact with the pixel electrode of the light-emitting element. When the second wiring is electrically connected to the pixel electrode of the light-emitting element via at least the channel formation region of the second transistor and the channel formation region of the fifth transistor, the second transistor and the fifth transistor are both turned on. The second transistor is a light-emitting device having the function of controlling the current supplied to the light-emitting element according to the potential, A first semiconductor film having a channel formation region for the second transistor and a channel formation region for the fifth transistor, A second semiconductor film having a channel formation region for the third transistor, A first conductive film having a region positioned above the first semiconductor film and functioning as the gate of the second transistor, A second conductive film having a region positioned above the first semiconductor film and functioning as the gate of the fifth transistor, A third conductive film having a region positioned above the second semiconductor film and functioning as the gate of the third transistor, The first signal input to the gate of the third transistor is different from the second signal input to the gate of the first transistor. The first semiconductor film has a curved shape in the channel formation region of the second transistor. Light-emitting device.

3. It has multiple pixels in the pixel area, At least one of the plurality of pixels has a first transistor to a fifth transistor and a light-emitting element. The first transistor has the function of controlling the input of an image signal to the first pixel, The source or drain of the second transistor is always in electrical contact with the source or drain of the fifth transistor. Either the source or drain of the third transistor is always in contact with the gate of the second transistor. The third transistor has the function of inputting a potential corresponding to the image signal to the gate of the second transistor via the channel formation region of the third transistor. Either the source or drain of the fourth transistor is always in contact with the gate of the second transistor. The source or drain of the fourth transistor is always in electrical contact with the first wiring. The source or drain of the fifth transistor is always in electrical contact with the pixel electrode of the light-emitting element. When the second wiring is electrically connected to the pixel electrode of the light-emitting element via at least the channel formation region of the second transistor and the channel formation region of the fifth transistor, the second transistor and the fifth transistor are both turned on. The second transistor is a light-emitting device having the function of controlling the current supplied to the light-emitting element according to the potential, A first semiconductor film having a channel formation region for the second transistor and a channel formation region for the fifth transistor, A second semiconductor film having a channel formation region for the third transistor, A first conductive film having a region positioned above the first semiconductor film and functioning as the gate of the second transistor, A second conductive film having a region positioned above the first semiconductor film and functioning as the gate of the fifth transistor, A third conductive film having a region positioned above the second semiconductor film and functioning as the gate of the third transistor, The second semiconductor film comprises an oxide semiconductor, The first semiconductor film has a curved shape in the channel formation region of the second transistor. Light-emitting device.

4. It has multiple pixels in the pixel area, At least one of the plurality of pixels has a first transistor to a fifth transistor and a light-emitting element. The first transistor has the function of controlling the input of an image signal to the first pixel, The source or drain of the second transistor is always in electrical contact with the source or drain of the fifth transistor. Either the source or drain of the third transistor is always in contact with the gate of the second transistor. The third transistor has the function of inputting a potential corresponding to the image signal to the gate of the second transistor via the channel formation region of the third transistor. Either the source or drain of the fourth transistor is always in contact with the gate of the second transistor. The source or drain of the fourth transistor is always in electrical contact with the first wiring. The source or drain of the fifth transistor is always in electrical contact with the pixel electrode of the light-emitting element. When the second wiring is electrically connected to the pixel electrode of the light-emitting element via at least the channel formation region of the second transistor and the channel formation region of the fifth transistor, the second transistor and the fifth transistor are both turned on. The second transistor is a light-emitting device having the function of controlling the current supplied to the light-emitting element according to the potential, A first semiconductor film having a channel formation region for the second transistor and a channel formation region for the fifth transistor, A second semiconductor film having a channel formation region for the third transistor, A first conductive film having a region positioned above the first semiconductor film and functioning as the gate of the second transistor, A second conductive film having a region positioned above the first semiconductor film and functioning as the gate of the fifth transistor, A third conductive film having a region positioned above the second semiconductor film and functioning as the gate of the third transistor, The second semiconductor film comprises an oxide semiconductor, The first signal input to the gate of the third transistor is different from the second signal input to the gate of the first transistor. The first semiconductor film has a curved shape in the channel formation region of the second transistor. Light-emitting device.

5. In any one of claims 1 to 4, The first conductive film is separated from the second conductive film. Light-emitting device.

6. In any one of claims 1 to 5, The insulating film has a region located above the first semiconductor film, Each of the first conductive film and the second conductive film has a region in contact with the insulating film. Light-emitting device.

7. In any one of claims 1 to 6, The first semiconductor film and the second semiconductor film are not a continuous semiconductor film. Light-emitting device.

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