Light-emitting device

Abstract

To provide a light-emitting device capable of inhibiting inter-pixel luminance variations due to variations in a threshold voltage of a transistor.SOLUTION: A light-emitting device at least comprises: a transistor, first wiring, 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 electrode of the capacitive element. The other electrode of the capacitive element is connected to one of a source and a drain of the transistor. The second switch has a function of selecting conduction or non-conduction between the second wiring and a gate of the transistor. The third switch has a function of selecting conduction or non-conduction between one electrode 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 a positive electrode of the light-emitting element.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] A display device using a light-emitting element has high visibility, is optimal for thinning, and has no viewing angle limitation, and thus is attracting attention as a display device to replace a CRT (cathode ray tube) or a liquid crystal display device. An active matrix type display device using a light-emitting element has a configuration that is specifically proposed by different manufacturers. Usually, at least a light-emitting element, a transistor (switching transistor) that controls the input of a video signal to a pixel, and a transistor (driving transistor) that controls the current value supplied to the light-emitting element are provided for each pixel. By making all the transistors provided for the pixels have the same polarity, in the manufacturing process of the transistors, steps such as adding an impurity element that imparts a single conductivity to the semiconductor film can be partially omitted. Patent Document 1 below describes a light-emitting element type display in which pixels are configured only with n-channel type transistors.

[0003]

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, in a light-emitting device, since the drain current of the driving transistor is supplied to the light-emitting element, if there is variation in the threshold voltage of the driving transistor among pixels, such variation will be reflected in the luminance of the light-emitting element. Therefore, a proposal for a pixel configuration capable of correcting the current value of the driving transistor in anticipation of the variation in the threshold voltage is an important issue in improving the image quality of the light-emitting device. Also, generally, the conductive film used as the anode of the light-emitting element is less likely to have its surface oxidized in the atmosphere than the conductive film used as the cathode of the light-emitting element. Moreover, since the conductive film used as the anode of the light-emitting element is usually formed by a sputtering method, when the anode is formed on the EL layer containing the light-emitting material, the EL layer is liable to be damaged by sputtering damage. Therefore, a light-emitting element having a structure in which the anode, EL layer, and cathode are laminated in this order has a simple manufacturing process and is likely to obtain high luminous efficiency. However, when an n-channel type driving transistor is combined with the light-emitting element having the above structure, the source of the driving transistor is connected to the anode of the light-emitting element. Thus, as the light-emitting material deteriorates and the voltage between the anode and cathode of the light-emitting element increases, the potential of the source in the driving transistor rises, and the voltage between the gate and the source (gate-source voltage) becomes small. Therefore, the drain current of the driving transistor, that is, the current supplied to the light-emitting element becomes small, and the luminance of the light-emitting element decreases. Against the backdrop of the above-described technology, one of the problems of the present invention is to provide a light-emitting device in which variation in luminance among pixels due to variation in the threshold voltage of the driving transistor is suppressed. Or

[0006]

[0007] ​​​​​​​​​​​​​​​The present invention provides a light-emitting device capable of suppressing a decrease in the luminance of a light-emitting element due to deterioration of an EL layer. One of the goals is to provide [Means for solving the problem]

[0008] One embodiment of the light emitting device of the present invention includes a transistor, a first wiring, a second wiring, and a first switch. a first switch, a second switch, a third switch, a fourth switch, a capacitance element, and a light emitting The first switch includes a first wiring and a pair of electrodes of the capacitor. The capacitance element has a function of selecting conduction or non-conduction between one of the pair of electrodes. The other of the two is connected to one of the source and drain of 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 is connected between one of the pair of electrodes of the capacitor and the gate of the transistor. The fourth switch has a function of selecting whether to conduct or not conduct between the transistors. A function of selecting electrical continuity or non-continuity between one of the source and drain and the anode of the light-emitting element. has.

[0009] Alternatively, one embodiment of a light-emitting device of the present invention includes a transistor, a first wiring, a second wiring, and A third wiring, a first switch, a second switch, a third switch, and a fourth switch The first switch has at least a first wiring, a capacitor, and a light-emitting element. The capacitance element has a function of selecting conduction or non-conduction between one of a pair of electrodes of the capacitance element. The other of the pair of electrodes of the capacitor is connected to one of the source and drain of the transistor and the The second switch is connected to the second wiring, the gate of the transistor, and 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 the source of the driving transistor. With the above - mentioned voltage applied, by making the source of the driving transistor floating (floating state), the threshold voltage can be obtained between the gate and the source of the driving transistor. Then, while keeping the source floating (floating state), when a voltage of an 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 the 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 performing threshold voltage correction and anode potential correction, improvement in the image quality of the light-emitting device can be achieved.

Brief Description of the Drawings

[0013]

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Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention ​Without being limited to the following description, various changes can be made to its form and details without departing from the spirit and scope of the present invention, which can be easily understood by those skilled in the art. Therefore, the present invention should not be construed as being limited to the description of the embodiments shown below.

[0015] Note that in this specification, the light-emitting device includes, within its scope, a panel in which a light-emitting element is formed in each pixel, and a module in a state where an IC including a controller is mounted on the panel.

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

[0017] Pixel 100 includes transistors 11 to 15, a capacitor element 16, and a light-emitting element 1 7. Note that in FIG. 1(A), the case where transistors 11 to 15 are of an n-channel type is illustrated.

[0018] Transistor 12 has a function of selecting conduction or non-conduction between wiring SL and one of a pair of electrodes of capacitor element 16. The other of the pair of electrodes of capacitor element 16 is connected to one of the source and drain of transistor 11. Transistor 13 has a function of selecting conduction or non-conduction between wiring IL and the gate of transistor 11. Transistor 14 has a function of selecting conduction or non-conduction between one of the pair of electrodes of capacitor element 16 and the gate of transistor 11. Transistor 15 has a function of selecting conduction or non-conduction between one of the source and drain of transistor 11 and the anode of light-emitting element 17.

[0019] ​​​​​​​ Further, in FIG. 1(A), the other of the source and drain of the transistor 11 is connected to the wiring VL. This connection continues.

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

[0021] Note that in this specification, "connection" means electrical connection, corresponding to a state where current, voltage, or potential can be supplied or transmitted. Therefore, the connected state does not necessarily refer to the state of direct connection, but also includes the state of indirect connection through elements such as wiring, conductive films, resistors, diodes, transistors, etc., so that current, voltage, or potential can be supplied or transmitted.

[0022] Also, even when components that are independent on the circuit diagram are connected, actually, for example, when a part of the wiring functions as an electrode, there may be a case where one conductive film has the functions of a plurality of components combined. In this specification, "connection" includes such a case where one conductive film has the functions of a plurality of components combined within its scope.

[0023] The light - emitting element 17 has an anode, a cathode, and an EL layer provided between the anode and the cathode. The EL ​​​​​​​​​​​​The layer is composed of a single layer or a plurality of layers, and at least includes a light-emitting layer containing a light-emitting substance among these layers. When the potential difference between the cathode and the anode, with the cathode as a reference, becomes equal to or higher than the threshold voltage Vthe of the light-emitting element 17, electroluminescence is obtained by the current supplied. Electroluminescence includes light emission (fluorescence) when returning from the singlet excited state to the ground state and light emission (phosphorescence) when returning from the triplet excited state to the ground state.

[0024] Note that the source and drain of the transistor change their names depending on the polarity of the transistor and the level of the potential applied to the source and drain. Generally, in an n-channel type transistor, the one with the lower potential applied is called the source, and the one with the higher potential applied is called the drain. In a p-channel type transistor, the one with the lower potential applied is called the drain, and the one with the higher potential applied is called the source. In this specification, for convenience, when explaining the connection relationship of the transistor, it is assumed that the source and drain are fixed, but actually, the names of the source and drain are interchanged according to the above potential relationship.

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

[0026] The pixel 100 includes transistors 11 to 15, a capacitor element 16, and a light-emitting element 17. In FIG. 1(B), the case where transistors 11 to 15 are of the n-channel type is illustrated as an example.

[0027] Transistor 12 has a function of selecting conduction or non - conduction between the wiring SL and one of the pair of electrodes of the capacitive element 16. Also, the other of the pair of electrodes of the capacitive element 16 is connected to one of the source and drain of the transistor 11 and the anode of the light - emitting element 17. Transistor 13 has a function of selecting conduction or non - conduction between the wiring IL and the gate of the transistor 11. Transistor 14 has a function of selecting conduction or non - conduction between one of the pair of electrodes of the capacitive element 16 and the gate of the transistor 11. Transistor 15 has a function of selecting conduction or non - conduction between one of the source and drain of the transistor 11 and the anode of the light - emitting element 17 and the wiring RL. Also, the other of the source and drain of the transistor 11 is connected to the wiring VL.

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

[0029] Note that in FIGS. 1(A) and 1(B), transistors 11 to 15 only need to have at least a gate on one side of the semiconductor film, but may have a pair of gates sandwiching the semiconductor film. One of the pair of gates is a front gate, and the other ​​​​​​​​​​​​​When the back gate is used, the back gate may be in a floating state or may be in a state where a potential is applied from another source. In the latter case, the same potential may be applied to the front gate and the back gate, or a fixed potential such as a ground potential may be applied only to the back gate. By controlling the height of the potential applied to the back gate, the threshold voltage of the transistor can be controlled. Also, by providing a back gate, the channel formation region increases, and an increase in drain current can be realized. Also, by providing a back gate, a depletion layer is likely to be formed in the semiconductor film, so the S value can be improved.

[0030] Also, in FIGS. 1(A) and 1(B), the case where all of the transistors 11 to 15 are n-channel type is illustrated. When all of the transistors 11 to 15 have the same polarity, in the manufacturing process of the transistor, steps such as adding an impurity element that imparts a single conductivity to the semiconductor film can be partially omitted. However, in the light-emitting device according to one aspect of the present invention, it is not necessarily the case that all of the transistors 11 to 15 are n-channel type. When the anode of the light-emitting element 17 is connected to one of the source and drain of the transistor 15, it is desirable that at least the transistor 11 is n-channel type, and when the cathode of the light-emitting element 17 is connected to one of the source and drain of the transistor 15, it is desirable that at least the transistor 11 is p-channel type.

[0031] Also, when operating the transistor 11 in the saturation region when flowing a current, the channel length or ​​​​​​It is desirable to make the channel width longer than that of transistors 12 to 15. . By increasing the channel length or the channel width, the characteristics in the saturation region become flat , and the kink effect can be reduced. Alternatively, by increasing the channel length or the channel width, transistor 11 can conduct a large amount of current even in the saturation region. .

[0032] Also, in FIGS. 1(A) and 1(B), transistors 11 to 15 are shown as an example of a single-gate structure having a single gate and thus a single channel formation region, but the present invention is not limited to this configuration. Any one or all of transistors 11 to 15 may have a multi-gate structure having a plurality of electrically connected gates and thus a plurality of channel formation regions.

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

[0034] FIG. 2 illustrates, in a timing chart, the potentials of wirings G1 to G3 connected to pixel 100 shown in FIG. 1(A) and the potential Vdata supplied to wiring SL. However, the timing chart shown in FIG. 2 illustrates the case where transistors 11 to 15 are of the n-channel type. As shown in FIG. 2, the operation of pixel 100 shown in FIG. 1(A) can be mainly divided into a first operation in period 1, a second operation in period 2, and a third operation in period 3.

[0035] First, the first operation performed in period 1 will be described. In period 1, a low potential is applied to wiring G1. A low-level potential is applied to wiring G1, a low-level potential is applied to wiring G2, and a high-level potential is applied to wiring G3. Therefore, transistor 15 becomes conductive, and transistors 1 2 to 14 become non-conductive.

[0036] Also, a potential Vano is applied to wiring VL, and a potential Vcat is applied to the cathode of light-emitting element 17. The potential Vano is set to be higher than the potential obtained by adding the threshold voltage Vthe of the light-emitting element 17 to the potential Vcat. Hereinafter, it is assumed that the threshold voltage Vthe of the light-emitting element 17 is 0.

[0037] Fig. 3(A) shows the operation of pixel 100 in period 1. In Fig. 3(A), transistors 12 to 15 are shown as switches. In period 1, due to the above operation, one of the source and drain of transistor 11 (illustrated as node A) becomes a potential obtained by adding the threshold voltage Vthe of the light-emitting element 17 to the potential Vcat. In Fig. 3(A), since it is assumed that the threshold voltage Vthe is 0, the potential of node A becomes the potential Vcat.

[0038] Next, the second operation performed in period 2 will be described. In period 2, a high-level potential is applied to wiring G1, a low-level potential is applied to wiring G2, and a low-level potential is applied to wiring G3. Therefore, transistors 12 and 13 become conductive, and transistors 14 and 15 become non-conductive.

[0039] When transitioning from period 1 to period 2, the potential applied to wiring G1 changes from low level to high level. ​​​​​​​​​​After switching to the loop, it is desirable to switch the potential applied to wiring G3 from a high level to a low level. With the above configuration, by switching the potential applied to wiring G1, it is possible to prevent the potential at node A from fluctuating. A potential Vano is applied to wiring VL, and a potential Vcat is applied to the cathode of light-emitting element 17. Then, a potential V0 is applied to wiring IL, and a potential Vdata of an image signal is applied to wiring SL. Note that it is desirable that the potential V0 is higher than the potential obtained by adding the threshold voltage Vth of transistor 11 and the threshold voltage Vthe of light-emitting element 17 to the potential Vcat, and lower than the potential obtained by adding the threshold voltage Vth of transistor 11 to the potential Vano.

[0040] Also, a potential Vano is applied to wiring VL, and a potential Vcat is applied to the cathode of light-emitting element 17. Then, a potential V0 is applied to wiring IL, and a potential Vdata of an image signal is applied to wiring SL. Note that it is desirable that the potential V0 is higher than the potential obtained by adding the threshold voltage Vth of transistor 11 and the threshold voltage Vthe of light-emitting element 17 to the potential Vcat, and lower than the potential obtained by adding the threshold voltage Vth of transistor 11 to the potential Vano. A potential Vano is applied to wiring VL, and a potential Vcat is applied to the cathode of light-emitting element 17. Then, a potential V0 is applied to wiring IL, and a potential Vdata of an image signal is applied to wiring SL. Note that it is desirable that the potential V0 is higher than the potential obtained by adding the threshold voltage Vth of transistor 11 and the threshold voltage Vthe of light-emitting element 17 to the potential Vcat, and lower than the potential obtained by adding the threshold voltage Vth of transistor 11 to the potential Vano. A potential Vano is applied to wiring VL, and a potential Vcat is applied to the cathode of light-emitting element 17. Then, a potential V0 is applied to wiring IL, and a potential Vdata of an image signal is applied to wiring SL. Note that it is desirable that the potential V0 is higher than the potential obtained by adding the threshold voltage Vth of transistor 11 and the threshold voltage Vthe of light-emitting element 17 to the potential Vcat, and lower than the potential obtained by adding the threshold voltage Vth of transistor 11 to the potential Vano. A potential Vano is applied to wiring VL, and a potential Vcat is applied to the cathode of light-emitting element 17. Then, a potential V0 is applied to wiring IL, and a potential Vdata of an image signal is applied to wiring SL. Note that it is desirable that the potential V0 is higher than the potential obtained by adding the threshold voltage Vth of transistor 11 and the threshold voltage Vthe of light-emitting element 17 to the potential Vcat, and lower than the potential obtained by adding the threshold voltage Vth of transistor 11 to the potential Vano. A potential Vano is applied to wiring VL, and a potential Vcat is applied to the cathode of light-emitting element 17. Then, a potential V0 is applied to wiring IL, and a potential Vdata of an image signal is applied to wiring SL. Note that it is desirable that the potential V0 is higher than the potential obtained by adding the threshold voltage Vth of transistor 11 and the threshold voltage Vthe of light-emitting element 17 to the potential Vcat, and lower than the potential obtained by adding the threshold voltage Vth of transistor 11 to the potential Vano.

[0041] Fig. 3(B) shows the operation of pixel 100 in period 2. In Fig. 3(B), transistors 12 to 15 are shown as switches. In period 2, due to the above operation, a potential V0 is applied to the gate of transistor 11 (shown as node B), so transistor 11 becomes conductive. Therefore, the charge in capacitor 16 is discharged through transistor 11, and the potential of node A, which was Vcat, begins to rise. Finally, when the potential of node A becomes V0 - Vth, that is, when the gate voltage of transistor 11 becomes as small as the threshold voltage Vth, transistor 11 becomes non-conductive. Also, a potential Vdata is applied to one electrode of capacitor 16 (shown as node C). Fig. 3(B) shows the operation of pixel 100 in period 2. In Fig. 3(B), transistors 12 to 15 are shown as switches. In period 2, due to the above operation, a potential V0 is applied to the gate of transistor 11 (shown as node B), so transistor 11 becomes conductive. Therefore, the charge in capacitor 16 is discharged through transistor 11, and the potential of node A, which was Vcat, begins to rise. Finally, when the potential of node A becomes V0 - Vth, that is, when the gate voltage of transistor 11 becomes as small as the threshold voltage Vth, transistor 11 becomes non-conductive. Also, a potential Vdata is applied to one electrode of capacitor 16 (shown as node C). Fig. 3(B) shows the operation of pixel 100 in period 2. In Fig. 3(B), transistors 12 to 15 are shown as switches. In period 2, due to the above operation, a potential V0 is applied to the gate of transistor 11 (shown as node B), so transistor 11 becomes conductive. Therefore, the charge in capacitor 16 is discharged through transistor 11, and the potential of node A, which was Vcat, begins to rise. Finally, when the potential of node A becomes V0 - Vth, that is, when the gate voltage of transistor 11 becomes as small as the threshold voltage Vth, transistor 11 becomes non-conductive. Also, a potential Vdata is applied to one electrode of capacitor 16 (shown as node C). Fig. 3(B) shows the operation of pixel 100 in period 2. In Fig. 3(B), transistors 12 to 15 are shown as switches. In period 2, due to the above operation, a potential V0 is applied to the gate of transistor 11 (shown as node B), so transistor 11 becomes conductive. Therefore, the charge in capacitor 16 is discharged through transistor 11, and the potential of node A, which was Vcat, begins to rise. Finally, when the potential of node A becomes V0 - Vth, that is, when the gate voltage of transistor 11 becomes as small as the threshold voltage Vth, transistor 11 becomes non-conductive. Also, a potential Vdata is applied to one electrode of capacitor 16 (shown as node C). Fig. 3(B) shows the operation of pixel 100 in period 2. In Fig. 3(B), transistors 12 to 15 are shown as switches. In period 2, due to the above operation, a potential V0 is applied to the gate of transistor 11 (shown as node B), so transistor 11 becomes conductive. Therefore, the charge in capacitor 16 is discharged through transistor 11, and the potential of node A, which was Vcat, begins to rise. Finally, when the potential of node A becomes V0 - Vth, that is, when the gate voltage of transistor 11 becomes as small as the threshold voltage Vth, transistor 11 becomes non-conductive. Also, a potential Vdata is applied to one electrode of capacitor 16 (shown as node C). Fig. 3(B) shows the operation of pixel 100 in period 2. In Fig. 3(B), transistors 12 to 15 are shown as switches. In period 2, due to the above operation, a potential V0 is applied to the gate of transistor 11 (shown as node B), so transistor 11 becomes conductive. Therefore, the charge in capacitor 16 is discharged through transistor 11, and the potential of node A, which was Vcat, begins to rise. Finally, when the potential of node A becomes V0 - Vth, that is, when the gate voltage of transistor 11 becomes as small as the threshold voltage Vth, transistor 11 becomes non-conductive. Also, a potential Vdata is applied to one electrode of capacitor 16 (shown as node C). Fig. 3(B) shows the operation of pixel 100 in period 2. In Fig. 3(B), transistors 12 to 15 are shown as switches. In period 2, due to the above operation, a potential V0 is applied to the gate of transistor 11 (shown as node B), so transistor 11 becomes conductive. Therefore, the charge in capacitor 16 is discharged through transistor 11, and the potential of node A, which was Vcat, begins to rise. Finally, when the potential of node A becomes V0 - Vth, that is, when the gate voltage of transistor 11 becomes as small as the threshold voltage Vth, transistor 11 becomes non-conductive. Also, a potential Vdata is applied to one electrode of capacitor 16 (shown as node C). Fig. 3(B) shows the operation of pixel 100 in period 2. In Fig. 3(B), transistors 12 to 15 are shown as switches. In period 2, due to the above operation, a potential V0 is applied to the gate of transistor 11 (shown as node B), so transistor 11 becomes conductive. Therefore, the charge in capacitor 16 is discharged through transistor 11, and the potential of node A, which was Vcat, begins to rise. Finally, when the potential of node A becomes V0 - Vth, that is, when the gate voltage of transistor 11 becomes as small as the threshold voltage Vth, transistor 11 becomes non-conductive. Also, a potential Vdata is applied to one electrode of capacitor 16 (shown as node C). Fig. 3(B) shows the operation of pixel 100 in period 2. In Fig. 3(B), transistors 12 to 15 are shown as switches. In period 2, due to the above operation, a potential V0 is applied to the gate of transistor 11 (shown as node B), so transistor 11 becomes conductive. Therefore, the charge in capacitor 16 is discharged through transistor 11, and the potential of node A, which was Vcat, begins to rise. Finally, when the potential of node A becomes V0 - Vth, that is, when the gate voltage of transistor 11 becomes as small as the threshold voltage Vth, transistor 11 becomes non-conductive. Also, a potential Vdata is applied to one electrode of capacitor 16 (shown as node C).

[0042] Next, the third operation performed in period 3 will be described. In period 3, on wiring G1 A low-level potential is applied, a high-level potential is applied to wiring G2, and a high level potential is applied to wiring G3. Thus, transistors 14 and 15 are in the conductive state and transistors 12 and 13 are in the non-conductive state.

[0043] When shifting from period 2 to period 3, it is desirable to switch the potential applied to wiring G1 from high level to low level and then switch the potentials applied to wiring G2 and wiring G3 from low level to high level. With the above configuration, by switching the potential applied to wiring G1, it is possible to prevent the potential at node A from fluctuating.

[0044] Also, a potential Vano is applied to wiring VL, and a potential Vcat is applied to the cathode of light-emitting element 17.

[0045] Fig. 3(C) shows the operation of pixel 100 in period 3. In Fig. 3(C), transistors 12 to 15 are shown as switches. In period 3, due to the above operation a potential Vdata is applied to node B, so the gate voltage of transistor 11 becomes Vdata - V0 + Vth. Thus, the gate voltage of transistor 11 can be set to a value with the threshold voltage Vth taken into account. With the above configuration, it is possible to prevent variations in the threshold voltage Vth of transistor 11 from affecting the current value supplied to light-emitting element 17. Or, even if transistor 11 deteriorates and the threshold voltage Vth changes, it is possible to prevent the above change from affecting the current value supplied to light-emitting element 17. Thus, display unevenness can be reduced and high-quality display can be performed.

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

[0047] FIG. 4 illustrates, in a timing chart, the potentials of wirings G1 to G3 connected to pixel 100 shown in FIG. 1(B) and the potential Vdata supplied to wiring SL. However, the timing chart shown in FIG. 4 illustrates the case where transistors 11 to 15 are n-channel type. As shown in FIG. 4, the operation of pixel 100 shown in FIG. 1(B) can be mainly divided into a first operation in period 1, a second operation in period 2, and a third operation in period 3. FIG. 4 illustrates, in a timing chart, the potentials of wirings G1 to G3 connected to pixel 100 shown in FIG. 1(B) and the potential Vdata supplied to wiring SL. However, the timing chart shown in FIG. 4 illustrates the case where transistors 11 to 15 are n-channel type. As shown in FIG. 4, the operation of pixel 100 shown in FIG. 1(B) can be mainly divided into a first operation in period 1, a second operation in period 2, and a third operation in period 3. FIG. 4 illustrates, in a timing chart, the potentials of wirings G1 to G3 connected to pixel 100 shown in FIG. 1(B) and the potential Vdata supplied to wiring SL. However, the timing chart shown in FIG. 4 illustrates the case where transistors 11 to 15 are n-channel type. As shown in FIG. 4, the operation of pixel 100 shown in FIG. 1(B) can be mainly divided into a first operation in period 1, a second operation in period 2, and a third operation in period 3. FIG. 4 illustrates, in a timing chart, the potentials of wirings G1 to G3 connected to pixel 100 shown in FIG. 1(B) and the potential Vdata supplied to wiring SL. However, the timing chart shown in FIG. 4 illustrates the case where transistors 11 to 15 are n-channel type. As shown in FIG. 4, the operation of pixel 100 shown in FIG. 1(B) can be mainly divided into a first operation in period 1, a second operation in period 2, and a third operation in period 3. FIG. 4 illustrates, in a timing chart, the potentials of wirings G1 to G3 connected to pixel 100 shown in FIG. 1(B) and the potential Vdata supplied to wiring SL. However, the timing chart shown in FIG. 4 illustrates the case where transistors 11 to 15 are n-channel type. As shown in FIG. 4, the operation of pixel 100 shown in FIG. 1(B) can be mainly divided into a first operation in period 1, a second operation in period 2, and a third operation in period 3. FIG. 4 illustrates, in a timing chart, the potentials of wirings G1 to G3 connected to pixel 100 shown in FIG. 1(B) and the potential Vdata supplied to wiring SL. However, the timing chart shown in FIG. 4 illustrates the case where transistors 11 to 15 are n-channel type. As shown in FIG. 4, the operation of pixel 100 shown in FIG. 1(B) can be mainly divided into a first operation in period 1, a second operation in period 2, and a third operation in period 3.

[0048] First, the first operation performed in period 1 will be described. In period 1, a low-level potential is applied to wiring G1, a low-level potential is applied to wiring G2, and a high-level potential is applied to wiring G3. Therefore, transistor 15 becomes conductive, and transistors 12 to 14 become non-conductive. First, the first operation performed in period 1 will be described. In period 1, a low-level potential is applied to wiring G1, a low-level potential is applied to wiring G2, and a high-level potential is applied to wiring G3. Therefore, transistor 15 becomes conductive, and transistors 12 to 14 become non-conductive. First, the first operation performed in period 1 will be described. In period 1, a low-level potential is applied to wiring G1, a low-level potential is applied to wiring G2, and a high-level potential is applied to wiring G3. Therefore, transistor 15 becomes conductive, and transistors 12 to 14 become non-conductive. First, the first operation performed in period 1 will be described. In period 1, a low-level potential is applied to wiring G1, a low-level potential is applied to wiring G2, and a high-level potential is applied to wiring G3. Therefore, transistor 15 becomes conductive, and transistors 12 to 14 become non-conductive.

[0049] Also, potential Vano is applied to wiring VL, and potential Vcat is applied to the cathode of light-emitting element 17. Potential Vano is set to be higher than the potential obtained by adding threshold voltage Vthe of light-emitting element 17 to potential Vcat, as described above. Further, potential V1 is applied to wiring RL. It is desirable that potential V1 is lower than the potential obtained by adding threshold voltage Vthe of light-emitting element 17 to potential Vcat. By setting potential V1 to the above value, current flow through light-emitting element 17 in period 1 can be prevented. Also, potential Vano is applied to wiring VL, and potential Vcat is applied to the cathode of light-emitting element 17. Potential Vano is set to be higher than the potential obtained by adding threshold voltage Vthe of light-emitting element 17 to potential Vcat, as described above. Further, potential V1 is applied to wiring RL. It is desirable that potential V1 is lower than the potential obtained by adding threshold voltage Vthe of light-emitting element 17 to potential Vcat. By setting potential V1 to the above value, current flow through light-emitting element 17 in period 1 can be prevented. Also, potential Vano is applied to wiring VL, and potential Vcat is applied to the cathode of light-emitting element 17. Potential Vano is set to be higher than the potential obtained by adding threshold voltage Vthe of light-emitting element 17 to potential Vcat, as described above. Further, potential V1 is applied to wiring RL. It is desirable that potential V1 is lower than the potential obtained by adding threshold voltage Vthe of light-emitting element 17 to potential Vcat. By setting potential V1 to the above value, current flow through light-emitting element 17 in period 1 can be prevented. Also, potential Vano is applied to wiring VL, and potential Vcat is applied to the cathode of light-emitting element 17. Potential Vano is set to be higher than the potential obtained by adding threshold voltage Vthe of light-emitting element 17 to potential Vcat, as described above. Further, potential V1 is applied to wiring RL. It is desirable that potential V1 is lower than the potential obtained by adding threshold voltage Vthe of light-emitting element 17 to potential Vcat. By setting potential V1 to the above value, current flow through light-emitting element 17 in period 1 can be prevented. Also, potential Vano is applied to wiring VL, and potential Vcat is applied to the cathode of light-emitting element 17. Potential Vano is set to be higher than the potential obtained by adding threshold voltage Vthe of light-emitting element 17 to potential Vcat, as described above. Further, potential V1 is applied to wiring RL. It is desirable that potential V1 is lower than the potential obtained by adding threshold voltage Vthe of light-emitting element 17 to potential Vcat. By setting potential V1 to the above value, current flow through light-emitting element 17 in period 1 can be prevented. Also, potential Vano is applied to wiring VL, and potential Vcat is applied to the cathode of light-emitting element 17. Potential Vano is set to be higher than the potential obtained by adding threshold voltage Vthe of light-emitting element 17 to potential Vcat, as described above. Further, potential V1 is applied to wiring RL. It is desirable that potential V1 is lower than the potential obtained by adding threshold voltage Vthe of light-emitting element 17 to potential Vcat. By setting potential V1 to the above value, current flow through light-emitting element 17 in period 1 can be prevented.

[0050] FIG. 5(A) shows the operation of pixel 100 in period 1. Note that in FIG. 5(A), the transistors Transistors 12 to 15 are denoted as switches. In period 1, the above operation applies a potential V1 to one of the source and drain of transistor 11 (illustrated as node A). The potential V1 is applied.

[0051] Next, the second operation performed in period 2 will be described. In period 2, a high-level potential is applied to wiring G1, a low-level potential is applied to wiring G2, and a low-level potential is applied to wiring G3. Therefore, transistors 12 and 13 are in the conducting state while transistors 14 and 15 are in the non-conducting state. and transistors 14 and 15 are in the non-conducting state.

[0052] When transitioning from period 1 to period 2, it is desirable that after the potential applied to wiring G1 is switched from the low level to the high level, the potential applied to wiring G3 is switched from the high level to the low level. With the above configuration, by switching the potential applied to wiring G1, it is possible to prevent the potential at node A from fluctuating. A from fluctuating.

[0053] Also, a potential Vano is applied to wiring VL, and a potential Vcat is applied to the cathode of light-emitting element 17. A potential V0 is applied to wiring IL, and a potential Vdata of an image signal is applied to wiring SL. Note that, as described above, the potential V0 is desirably higher than the potential obtained by adding the threshold voltage Vth of transistor 11 and the threshold voltage Vthe of light-emitting element 17 to the potential Vcat, and lower than the potential obtained by adding the threshold voltage Vth of transistor 11 to the potential Vano. However, unlike the case of pixel 100 shown in FIG. 1(A), in the case of pixel 10 0 shown in FIG. 1(B), the anode of light-emitting element 17 and one of the source and drain of transistor 11 are connected. ​​​​is connected. Therefore, in order to keep the current value supplied to the light-emitting element 17 small during period 2, in the case of the pixel 100 shown in FIG. 1(B), it is desirable to set the potential V0 to a lower value than in the case of the pixel 100 shown in FIG. 1(A).

[0054] FIG. 5(B) shows the operation of the pixel 100 in period 2. In FIG. 5(B), the transistors 12 to 15 are shown as switches. In period 2, due to the above operation, the potential V0 is applied to the gate of the transistor 11 (shown as node B), so that the transistor 11 becomes conductive. Therefore, the charge of the capacitor element 16 is discharged through the transistor 11, and the potential of node A, which was V1, starts to rise. And finally, when the potential of node A becomes V0 - Vth, that is, when the gate voltage of the transistor 11 becomes as small as the threshold voltage Vth, the transistor 11 becomes non-conductive. Also, a potential Vdata is applied to one electrode of the capacitor element 16 (shown as node C).

[0055] Next, the third operation performed in period 3 will be described. In period 3, a low-level potential is applied to the wiring G1, a high-level potential is applied to the wiring G2, and a low-level potential is applied to the wiring G3. Therefore, the transistor 14 becomes conductive, and the transistors 12, 13, and 15 become non-conductive.

[0056] Note that when shifting from period 2 to period 3, after the potential applied to the wiring G1 is switched from high level to low level, the potential applied to the wiring G2 is switched from low level to high level. ​​​​​​​It is desirable. With the above configuration, by switching the potential applied to the wiring G1, it is possible to prevent the potential at the node A from fluctuating.

[0057] Also, a potential Vano is applied to the wiring VL, and a potential Vcat is applied to the cathode of the light-emitting element 17. is applied.

[0058] Fig. 5(C) shows the operation of the pixel 100 in period 3. In Fig. 5(C), the transistors 12 to 15 are represented as switches. In period 3, due to the above operation, a potential Vdata is applied to the node B, so the gate voltage of the transistor 11 becomes Vdata - V0 + Vth. Therefore, the gate voltage of the transistor 11 can be set to a value with the threshold voltage Vth taken into account. With the above configuration, it is possible to prevent variations in the threshold voltage Vth of the transistor 11 from affecting the current value supplied to the light-emitting element 17. Or, even if the transistor 11 deteriorates and the threshold voltage Vth changes, it is possible to prevent the above change from affecting the current value supplied to the light-emitting element 17. Therefore, display non-uniformity can be reduced, and high-quality display can be performed. In the light-emitting element type display described in Patent Document 1, the gate and drain of the transistor (Tr12) for supplying current to the organic EL element are electrically connected to obtain the threshold voltage. Therefore, when the transistor (Tr12) is in the normal-on state, the source of the transistor

[0059] (Tr12) will not be higher than the gate. Therefore, when the transistor (Tr12) is in the normal-on state, it is difficult to obtain the threshold voltage. (Tr12).

[0060] ​​​On the other hand, in the light-emitting device according to one embodiment of the present invention having the pixels shown in FIGS. 1(A) and 1(B). Since the source and the other drain of the transistor 11 and the gate of the transistor 11 are electrically separated, the respective potentials can be controlled individually. Therefore, in the second operation, the potential of the source and the other drain of the transistor 11 can be set to a value higher than the potential obtained by adding the threshold voltage Vth to the potential of the gate of the transistor 11. Therefore, when the transistor 11 is normally-on, that is, when the threshold voltage Vt h has a negative value, in the transistor 11, charges can be accumulated in the capacitive element 16 until the potential of the source becomes higher than the potential V0 of the gate. Therefore, in the light-emitting device according to one embodiment of the present invention, even when the transistor 11 is normally-on, the threshold voltage can be obtained in the above described second operation, and in the third operation, the gate voltage of the transistor 11 can be set to a value taking into account the threshold voltage V th. Therefore, in the light-emitting device according to one embodiment of the present invention, for example, when an oxide semiconductor is used for the semiconductor film of the transistor 11, even if the transistor 11 becomes normally-on, display noise can be reduced, and high-quality display can be performed.

[0061] Accordingly, in the light-emitting device according to one embodiment of the present invention, for example, when an oxide semiconductor is used for the semiconductor film of the transistor 11, even if the transistor 11 becomes normally-on, display noise can be reduced, and high-quality display can be performed.

[0062] (Embodiment 2) FIG. 6 shows a top view of the pixel shown in FIG. 1(A) as an example. In FIG. 6, for the sake of clearly showing the layout of the pixel, various insulating films are omitted, and a top view of the pixel is shown. Also, in FIG. 6, for the sake of clearly showing the layout of the transistor and the capacitive element included in the pixel, the anode is omitted, and a top view of the pixel is shown with the EL layer and the cathode omitted. ​​​

[0063] FIG. 7 is a cross-sectional view taken along dashed lines A1-A2 and A3-A4 in the top view shown in FIG. Shows.

[0064] The transistor 12 is formed by forming a conductive film 8 functioning as a gate on a substrate 800 having an insulating surface. 801, a gate insulating film 802 on the conductive film 801, and a gate insulating film 803 at a position overlapping the conductive film 801. A semiconductor film 803 located on the gate insulating film 802 and a gate insulating film 803 functioning as a source or drain. The conductive film 801 includes a conductive film 804 and a conductive film 805 located over the semiconductor film 803. The conductive film 804 also functions as a wiring G1.

[0065] The transistor 13 is formed by forming a conductive film 8 functioning as a gate on a substrate 800 having an insulating surface. 801, a gate insulating film 802 on the conductive film 801, and a gate insulating film 803 at a position overlapping the conductive film 801. A semiconductor film 806 located on the gate insulating film 802 and a gate insulating film 805 functioning as a source or drain. The conductive film 807 and the conductive film 808 are located over the semiconductor film 806. The conductive film 807 is , and is connected to a conductive film 809 functioning as a wiring IL via a contact hole.

[0066] The transistor 14 is formed by forming a conductive film 8 functioning as a gate on a substrate 800 having an insulating surface. 10, a gate insulating film 802 on the conductive film 810, and a gate insulating film 802 at a position overlapping the conductive film 810. A semiconductor film 811 located on the gate insulating film 802 and functioning as a source or drain, The conductive film 805 and the conductive film 808 are located over the semiconductor film 811. The conductive film 810 is , which also functions as wiring G2.

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

[0068] The transistor 15 includes a conductive film 8 16 that functions as a gate, a gate insulating film 802 on the conductive film 816, and a semiconductor film 817 located on the gate insulating film 802 at a position overlapping the conductive film 816, which functions as a source or a drain, and has a conductive film 815 and a conductive film 818 located on the semiconductor film 817. The conductive film 816 is also functions as a wiring G3.

[0069] The capacitor element 16 includes a conductive film 819, a gate insulating film 802 on the conductive film 819, and a conductive film 815 located on the gate insulating film 802 at a position overlapping the conductive film 819 on a substrate 800 having an insulating surface. The conductive film 819 is connected to the conductive film 805.

[0070] Also, an insulating film 820 is formed on the conductive films 804, 805, 807, 808, 814, 815, and 818. And a conductive film 822 that functions as an anode is provided on the insulating film 821. The conductive film 822 is connected to the conductive film 818 through a contact hole 823 formed in the insulating film 820 and the insulating film 821.

[0071] Also, an insulating film 824 having an opening through which a part of the conductive film 822 is exposed is provided on the insulating film 82 ​​​​​1 is provided thereon. On a part of the conductive film 822 and the insulating film 824, an EL layer 825 and a conductive film 826 functioning as a cathode are provided so as to be laminated in order. The conductive film 82 2, the EL layer 825, and the conductive film 826 overlap in a region corresponding to the light-emitting element 17 .

[0072] Next, FIG. 8 shows a top view of the pixel shown in FIG. 1(A) as another example. In FIG. 8 , in order to clearly show the layout of the pixel, various insulating films are omitted, and a top view of the pixel is shown. Also, in FIG. 8, in order to clearly show the layout of the transistor and the capacitor element included in the pixel , the anode, the EL layer, and the cathode are omitted, and a top view of the pixel is shown.

[0073] Further, FIG. 9 shows cross-sectional views taken along broken lines A1-A2 and A3-A4 of the top view shown in FIG. 8 .

[0074] The transistor 12 includes a semiconductor film 901, a gate insulating film 902 on the semiconductor film 9 01, a conductive film 903 that functions as a gate and is located on the gate insulating film 90 2 at a position overlapping the semiconductor film 901, and conductive films 904 and 905 connected to a source or a drain included in the semiconductor film 901. The conductive film 903 also functions as a wiring G1. The conductive film 904 also functions as a wiring SL.

[0075] The transistor 13 includes a semiconductor film 906, a gate insulating film 902 on the semiconductor film 9 06, a conductive film 903 that functions as a gate and is located on the gate insulating film 90 2 at a position overlapping the semiconductor film 906, and a source or or a conductive film 907 and a conductive film 908 connected to the drain. The conductive film 907 is connected to a conductive film 909 that functions as a wiring IL through a contact hole.

[0076] The transistor 14 includes a semiconductor film 901, a gate insulating film 902 on the semiconductor film 9 01, a conductive film 911 that is located on the gate insulating film 902 and functions as a gate at a position overlapping the semiconductor film 901, and a conductive film 905 and a conductive film 908 connected to a source or a drain of the semiconductor film 901. The conductive film 911 also functions as a wiring G2. In FIG. 8, the transistor 12 and the transistor 14 share a single semiconductor film 901, but the transistor 12 and the transistor 14 may have independent semiconductor films. or a conductive film 905 and a conductive film 908 connected to a source or a drain of the semiconductor film 901. The conductive film 911 also functions as a wiring G2. In FIG. 8, the transistor 12 and the transistor 14 share a single semiconductor film 901, but the transistor 12 and the transistor 14 may have independent semiconductor films. also functions as a wiring G2. In FIG. 8, the transistor 12 and the transistor 14 share a single semiconductor film 901, but the transistor 12 and the transistor 14 may have independent semiconductor films. also functions as a wiring G2. In FIG. 8, the transistor 12 and the transistor 14 share a single semiconductor film 901, but the transistor 12 and the transistor 14 may have independent semiconductor films.

[0077] The transistor 11 includes a semiconductor film 912, a gate insulating film 902 on the semiconductor film 9 12, a conductive film 913 that is located on the gate insulating film 902 and functions as a gate at a position overlapping the semiconductor film 912, and a conductive film 914 connected to a source or a drain of the semiconductor film 912. The conductive film 913 is continued to the conductive film 908. The conductive film 914 also functions as a wiring VL. is continued to the conductive film 908. The conductive film 914 also functions as a wiring VL. is continued to the conductive film 908. The conductive film 914 also functions as a wiring VL.

[0078] The transistor 15 includes a semiconductor film 912, a gate insulating film 902 on the semiconductor film 9 12, a conductive film 915 that is located on the gate insulating film 902 and functions as a gate at a position overlapping the semiconductor film 912, and a conductive film 916 connected to a source or a drain of the semiconductor film 912. The conductive film 915 also functions as a wiring G3. also functions as a wiring G3. also functions as a wiring G3.

[0079] The capacitive element 16 includes a semiconductor film 912 and the semiconductor film 912 on a substrate 900 having an insulating surface. A gate insulating film 902 on the semiconductor film 912, and a conductive film 917 located on the gate insulating film 902 at a position overlapping the semiconductor film 912. The conductive film 917 is connected to the conductive film 905.

[0080] Then, an insulating film 920 is formed on the conductive films 904, 905, 907, 908, 914, and 916. On the insulating film 920, a conductive film 921 functioning as an anode is provided. The conductive film 921 is connected to the conductive film 916 through a contact hole 922 formed in the insulating film 920. Also, an insulating film 923 having an opening through which a part of the conductive film 921 is exposed is provided on the insulating film 920. An EL layer 924 and a conductive film 925 functioning as a cathode are provided so as to be laminated in order on a part of the conductive film 921 and the insulating film 923. A region where the conductive film 921, the EL layer 924, and the conductive film 925 overlap corresponds to the light-emitting element 17. On the insulating film 920, a conductive film 921 functioning as an anode is provided. The conductive film 921 is connected to the conductive film 916 through a contact hole 922 formed in the insulating film 920. Then, an insulating film 920 is formed on the conductive films 904, 905, 907, 908, 914, and 916. On the insulating film 920, a conductive film 921 functioning as an anode is provided. The conductive film 921 is connected to the conductive film 916 through a contact hole 922 formed in the insulating film 920.

[0081] Also, an insulating film 923 having an opening through which a part of the conductive film 921 is exposed is provided on the insulating film 920. An EL layer 924 and a conductive film 925 functioning as a cathode are provided so as to be laminated in order on a part of the conductive film 921 and the insulating film 923. A region where the conductive film 921, the EL layer 924, and the conductive film 925 overlap corresponds to the light-emitting element 17. On the insulating film 920, a conductive film 921 functioning as an anode is provided. The conductive film 921 is connected to the conductive film 916 through a contact hole 922 formed in the insulating film 920. Also, an insulating film 923 having an opening through which a part of the conductive film 921 is exposed is provided on the insulating film 920. An EL layer 924 and a conductive film 925 functioning as a cathode are provided so as to be laminated in order on a part of the conductive film 921 and the insulating film 923. A region where the conductive film 921, the EL layer 924, and the conductive film 925 overlap corresponds to the light-emitting element 17. A region where the conductive film 921, 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, the transistors 11 to 15 may use a semiconductor such as silicon or germanium, which is amorphous, microcrystalline, polycrystalline, or single-crystalline, for the semiconductor film, or a wide-gap semiconductor such as an oxide semiconductor may be used for the semiconductor film. When a semiconductor such as silicon or germanium, which is amorphous, microcrystalline, polycrystalline, or single-crystalline, is used for the semiconductor film of the transistors 11 to 15, to impart one conductivity In one aspect of the present invention, the transistors 11 to 15 may use a semiconductor such as silicon or germanium, which is amorphous, microcrystalline, polycrystalline, or single-crystalline, for the semiconductor film, or a wide-gap semiconductor such as an oxide semiconductor may be used for the semiconductor film. When a semiconductor such as silicon or germanium, which is amorphous, microcrystalline, polycrystalline, or single-crystalline, is used for the semiconductor film of the transistors 11 to 15, to impart one conductivity

[0083] When a semiconductor such as silicon or germanium, which is amorphous, microcrystalline, polycrystalline, or single-crystalline, is used for the semiconductor film of the transistors 11 to 15, to impart one conductivity When a semiconductor such as silicon or germanium, which is amorphous, microcrystalline, polycrystalline, or single-crystalline, is used for the semiconductor film of the transistors 11 to 15, to impart one conductivity Impurity elements are added to the semiconductor film to form an impurity region that functions as a source or a drain. For example, by adding phosphorus or arsenic to the semiconductor film, an impurity region having n-type conductivity can be formed. Also, for example, by adding boron to the semiconductor film, an impurity region having p-type conductivity can be formed. When an oxide semiconductor is used for the semiconductor film of Transistors 11 to 15, a dopant may be added to the semiconductor film to form an impurity region that functions as a source or a drain. Ion implantation can be used for the addition of the dopant. As the dopant, for example, noble gases such as helium, argon, and xenon, or Group 15 elements such as nitrogen, phosphorus, arsenic, and antimony can be used. For example, when nitrogen is used as the dopant, the concentration of nitrogen atoms in the impurity region is desirably 5×10 or more and 1×10

[0084] / cm or less. Note that as the silicon semiconductor, amorphous silicon produced by a vapor growth method such as plasma CVD or sputtering, polycrystalline silicon obtained by crystallizing amorphous silicon by treatment such as laser annealing, single crystal silicon obtained by implanting hydrogen ions or the like into a single crystal silicon wafer and peeling off the surface layer, or the like can be used. Also, as the oxide semiconductor, indium oxide, tin oxide, zinc oxide, binary metal oxides such as In-Zn-based oxides, Sn-Zn-based oxides, Al-Zn-based oxides, and Zn-Mg-based oxides can be used. For the addition of dopant, ion implantation method can be used. Dopants can be, for example, noble gases such as helium, argon, xenon, etc., or Group 15 elements such as nitrogen, phosphorus, arsenic, antimony, etc. For example, when nitrogen is used as a dopant, the concentration of nitrogen atoms in the impurity region is desirably 5×10 19 / cm 3 or more and 1×10 22 / c m 3 or less.

[0085] As for the silicon semiconductor, amorphous silicon formed by a vapor growth method such as plasma CVD method or sputtering method, polycrystalline silicon obtained by crystallizing amorphous silicon by treatment such as laser annealing, or single crystal silicon obtained by implanting hydrogen ions or the like into a single crystal silicon wafer and peeling off the surface layer can be used. In addition, as the oxide semiconductor, indium oxide, tin oxide, zinc oxide, binary metal oxides such as In-Zn-based oxides, Sn-Zn-based oxides, Al-Zn-based oxides, Zn-Mg-based oxides can be used. Note that as the silicon semiconductor, amorphous silicon produced by a vapor growth method such as plasma CVD or sputtering, polycrystalline silicon obtained by crystallizing amorphous silicon by treatment such as laser annealing, single crystal silicon obtained by implanting hydrogen ions or the like into a single crystal silicon wafer and peeling off the surface layer, or the like can be used.

[0086] Also, as the oxide semiconductor, indium oxide, tin oxide, zinc oxide, binary metal oxides such as In-Zn-based oxides, Sn-Zn-based oxides, Al-Zn-based oxides, Zn-Mg-based oxides In-Zn-based oxides, Sn-Zn-based oxides, Al-Zn-based oxides, Zn-Mg-based oxides which are binary metal oxides Oxides, Sn-Mg-based oxides, In-Mg-based oxides, In-Ga-based oxides, and ternary metal oxides The In-Ga-Zn-based oxide (also denoted as IGZO), which is a ternary metal oxide, In-Al-Zn-based oxide oxide, In-Sn-Zn-based oxide, Sn-Ga-Zn-based oxide, Al-Ga-Zn-based oxide oxide, Sn-Al-Zn-based oxide, In-Hf-Zn-based oxide, In-La-Zn-based oxide oxide, In-Ce-Zn-based oxide, In-Pr-Zn-based oxide, In-Nd-Zn-based oxide oxide, In-Sm-Zn-based oxide, In-Eu-Zn-based oxide, In-Gd-Zn-based oxide, I n-Tb-Zn-based oxide, In-Dy-Zn-based oxide, In-Ho-Zn-based oxide, In -Er-Zn-based oxide, In-Tm-Zn-based oxide, In-Yb-Zn-based oxide, In- Lu-Zn-based oxide, the In-Sn-Ga-Zn-based oxide, which is a quaternary metal oxide, In -Hf-Ga-Zn-based oxide, In-Al-Ga-Zn-based oxide, In-Sn-Al-Z n-based oxide, In-Sn-Hf-Zn-based oxide, In-Hf-Al-Zn-based oxide can be used.

[0087] Note that, for example, the In-Ga-Zn-based oxide means an oxide having In, Ga, and Zn, and the ratio of In, Ga, and Zn is not limited. Also, other metal elements than In, Ga, and Zn may be included.

[0088] Further, as the oxide semiconductor, a material represented by InMO3(ZnO) m (m > 0, and m is not an integer) may be used. Here, M represents one metal element or a plurality of metal elements selected from Ga, Fe, Mn, and Co. Also, as the oxide semiconductor, In2SnO5 (ZnO) n ​A material represented by (n>0 and n is an integer) may be used.

[0089] For example, In:Ga:Zn = 1:1:1 (= 1 / 3:1 / 3:1 / 3) or In:G a:Zn = 2:2:1 (= 2 / 5:2 / 5:1 / 5) atomic ratio In-Ga-Zn oxide s and oxides in the vicinity of its composition 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) original It is advisable to use In-Sn-Zn-based oxides with a child ratio and oxides in the vicinity of their composition.

[0090] In addition, as a stabilizer for reducing the variation in the electrical characteristics of transistors using the oxide semiconductor, it is preferable to have tin (Sn), hafnium (Hf), aluminum (Al), zircon ium (Zr), and titanium (Ti). As other stabilizers, It may have any one or a plurality of lanthanoids, lanthanum (La), cerium (Ce), praseodymium (Pr), ne odymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er )、thulium (Tm), ytterbium (Yb), lutetium (Lu). One or more of them may be present.

[0091] Note that impurities such as moisture or hydrogen that act as electron donors (donors) are reduced, and the oxide semiconductor (purified OS) purified by reducing oxygen vacancies is of type i (intrinsic semiconductor) or extremely close to type i. Therefore, using the above oxide semiconductor ​​The transistor has the characteristic that its off-current is extremely low. Also, the band gap of the oxide semiconductor is 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more and impurities such as moisture or hydrogen are sufficiently reduced, and the oxygen deficiency is reduced By using an oxide semiconductor film that has been purified to a high purity, the off-current of the transistor can be lowered.

[0092] Specifically, the fact that the off-current of a transistor using a highly purified oxide semiconductor for the semiconductor film is low can be proven by various experiments. For example, even in an element with a channel width of 1×10 6 μm and a channel length of 10 μm, when the voltage between the source electrode and the drain electrode (drain voltage) is in the range of 1 V to 10 V, the off-current is below the measurement limit of the semiconductor parameter analyzer, that is, a characteristic of 1×10 A or less can be obtained. In this case, it can be seen that the off-current corresponding to the value obtained by dividing the off-current by the channel width of the transistor is 100 zA / μm -13 or less. Also, a circuit is used in which a capacitor element and a transistor are connected, and the charge flowing into or flowing out of the capacitor element is controlled by the transistor to measure the off-current In this measurement, a highly purified oxide semiconductor film is used for the channel formation region of the transistor, and the off-current of the transistor is measured from the change in the charge amount per unit time of the capacitor element As a result, it was found that when the voltage between the source electrode and the drain electrode of the transistor is 3 V, an even lower off-current of several tens of yA / μm can be obtained In the measurement, a highly purified oxide semiconductor film is used for the channel formation region of the transistor, and the off-current of the transistor is measured from the change in the charge amount per unit time of the capacitor element In this measurement, a highly purified oxide semiconductor film is used for the channel formation region of the transistor, and the off-current of the transistor is measured from the change in the charge amount per unit time of the capacitor element As a result, it was found that when the voltage between the source electrode and the drain electrode of the transistor is 3 V, an even lower off-current of several tens of yA / μm can be obtained Therefore, a transistor using a highly purified oxide semiconductor film for the channel formation region The off-current is significantly lower than that of a transistor using crystalline silicon.

[0093] Note that, unless otherwise specified, in this specification, the off-current in an n-channel transistor refers to the current flowing between the source and the drain when the potential of the gate is 0 or less with the potential of the source as a reference in a state where the drain is at a higher potential than the source and the gate. Or, in this specification, the off-current in a p-channel transistor refers to the current flowing between the source and the drain when the potential of the gate is 0 or more with the potential of the source as a reference in a state where the drain is at a lower potential than the source and the gate.

[0094] Note that, for example, the oxide semiconductor film can be formed by a sputtering method using a target containing In (indium), Ga (gallium), and Zn ( zinc). When forming an In-Ga- Zn-based oxide semiconductor film by sputtering, preferably, a target of an In-Ga-Zn-based oxide represented by an atomic ratio of In :Ga:Zn = 1:1:1, 4:2:3, 3:1:2, 1:1:2, 2:1:3, or 3:1:4 is used. By forming an oxide semiconductor film using a target of an In-Ga-Zn-based oxide having the above atomic ratio , polycrystals or CAACs are likely to be formed. Also, the filling rate of the target containing In, Ga, and Zn is 90% or more and 100% or less, preferably 95% or more and less than 100% . By using a target with a high filling rate, the formed oxide semiconductor film becomes a dense film .

[0095] Note that when using an In-Zn-based oxide material as the oxide semiconductor, in the target used​​​​​ The atomic ratio of the metal elements is In:Zn = 50:1 to 1:2 (in terms of molar ratio, In2 O3:ZnO = 25:1 to 1:4), preferably In:Zn = 20:1 to 1:1 (in terms of molar ratio, In2O3:ZnO = 10:1 to 1:2), more preferably In:Zn = 15:1 to 1.5:1 (in terms of molar ratio, In2O3:ZnO = 15:2 to 3:4 ). For example, for a target used to form an oxide semiconductor film which is an In-Zn-based oxide , when the atomic ratio is In:Zn:O = X:Y:Z, Z > 1.5X + Y. By keeping the ratio of Zn within the above range, improvement in mobility can be achieved.

[0096] Specifically, for the oxide semiconductor film, a substrate is held in a processing chamber maintained in a reduced-pressure state, and while removing residual moisture in the processing chamber, a sputtering gas from which hydrogen and moisture have been removed is introduced, and it may be formed using the above-mentioned target. During film formation, the substrate temperature may be 100°C or higher and 600°C or lower, preferably 200°C or higher and 400°C or lower. By forming the film while heating the substrate, the impurity concentration contained in the formed oxide semiconductor film can be reduced. Also, damage due to sputtering can be reduced. To remove residual moisture in the processing chamber, it is preferable to use an adsorption-type vacuum pump. For example, it is preferable to use a cryopump, an ion pump, or a titanium sublimation pump. Also, as an exhaust means, a turbo pump with a cold trap added may be used. When evacuating the film formation chamber using a cryopump , for example, compounds containing hydrogen atoms such as hydrogen atoms and water (H2O) (more preferably compounds containing carbon atoms as well) are exhausted, so the concentration of impurities contained in the oxide semiconductor film formed in the processing chamber can be reduced. ​​​​​​​​

[0097] Note that in an oxide semiconductor film formed by sputtering or the like, a large amount of moisture or hydrogen ( including a hydroxyl group) may be contained as an impurity. Since moisture or hydrogen easily forms a donor level, it is an impurity for the oxide semiconductor. Therefore, in one aspect of the present invention, in order to reduce impurities such as moisture or hydrogen in the oxide semiconductor film (dehydration or dehydrogenation), the oxide semiconductor film is placed in a reduced-pressure atmosphere, an inert gas atmosphere such as nitrogen or a rare gas, an oxygen gas atmosphere, or ultra-dry air (when measured using a dew point meter of the CRDS (cavity ring-down laser spectroscopy ) method, the moisture content is 20 ppm (dew point conversion of -55 °C) or less, preferably 1 ppm or less, preferably 10 ppb or less of air) atmosphere, and heat treatment is performed. By performing heat treatment on the oxide semiconductor film, moisture or hydrogen in the oxide semiconductor film can be desorbed. Specifically, heat treatment may be performed at a temperature of 250 °C or higher and 750 °C or lower, preferably 400 °C or higher and less than the strain point of the substrate . For example, it may be performed at about 500 °C for 3 minutes or more and 6 minutes or less . If the RTA method is used for the heat treatment, dehydration or dehydrogenation can be performed in a short time, so that treatment can be performed even at a temperature exceeding the strain point of the glass substrate. Note that due to the above heat treatment, oxygen may be desorbed from the oxide semiconductor film, and oxygen deficiency may be formed in the oxide semiconductor film. Therefore, in one aspect of the present invention, an oxygen-containing insulating film is used as an insulating film such as a gate insulating film in contact with the oxide semiconductor film. Then, after forming the oxygen-containing insulating film, by performing heat treatment, oxygen is supplied from the insulating film to the oxide semiconductor film .

[0098]

[0099] ​​​​​​​​Do so. With the above configuration, the oxygen deficiency serving as a donor is reduced, and the stoichiometric composition ratio of the oxide semiconductor contained in the oxide semiconductor film can be satisfied. It is preferable that the oxide semiconductor film contains an amount of oxygen exceeding the stoichiometric composition ratio. As a result, the oxide semiconductor film can be made closer to the i-type, the variation in the electrical characteristics of the transistor due to oxygen deficiency can be reduced, and the improvement in the electrical characteristics can be realized. The oxide semiconductor film preferably contains oxygen in an amount exceeding the stoichiometric composition ratio. As a result, the oxide semiconductor film can be made closer to the i-type, the variation in the electrical characteristics of the transistor due to oxygen deficiency can be reduced, and the improvement in the electrical characteristics can be realized. The oxide semiconductor film preferably contains oxygen in an amount exceeding the stoichiometric composition ratio. As a result, the oxide semiconductor film can be made closer to the i-type, the variation in the electrical characteristics of the transistor due to oxygen deficiency can be reduced, and the improvement in the electrical characteristics can be realized. The oxide semiconductor film preferably contains oxygen in an amount exceeding the stoichiometric composition ratio. As a result, the oxide semiconductor film can be made closer to the i-type, the variation in the electrical characteristics of the transistor due to oxygen deficiency can be reduced, and the improvement in the electrical characteristics can be realized. The oxide semiconductor film preferably contains oxygen in an amount exceeding the stoichiometric composition ratio. As a result, the oxide semiconductor film can be made closer to the i-type, the variation in the electrical characteristics of the transistor due to oxygen deficiency can be reduced, and the improvement in the electrical characteristics can be realized.

[0100] Note that the heat treatment for supplying oxygen to the oxide semiconductor film is preferably performed at 200°C or higher and 400°C or lower, for example, at 250°C or higher and 350°C or lower, in an atmosphere of nitrogen, ultra-dry air, or a rare gas (such as argon or helium). It is desirable that the water content of the above gas is 20 ppm or less, preferably 1 ppm or less, and more preferably 10 ppb or less. Note that the heat treatment for supplying oxygen to the oxide semiconductor film is preferably performed at 200°C or higher and 400°C or lower, for example, at 250°C or higher and 350°C or lower, in an atmosphere of nitrogen, ultra-dry air, or a rare gas (such as argon or helium). It is desirable that the water content of the above gas is 20 ppm or less, preferably 1 ppm or less, and more preferably 10 ppb or less. Note that the heat treatment for supplying oxygen to the oxide semiconductor film is preferably performed at 200°C or higher and 400°C or lower, for example, at 250°C or higher and 350°C or lower, in an atmosphere of nitrogen, ultra-dry air, or a rare gas (such as argon or helium). It is desirable that the water content of the above gas is 20 ppm or less, preferably 1 ppm or less, and more preferably 10 ppb or less. Note that the heat treatment for supplying oxygen to the oxide semiconductor film is preferably performed at 200°C or higher and 400°C or lower, for example, at 250°C or higher and 350°C or lower, in an atmosphere of nitrogen, ultra-dry air, or a rare gas (such as argon or helium). It is desirable that the water content of the above gas is 20 ppm or less, preferably 1 ppm or less, and more preferably 10 ppb or less.

[0101] Also, the oxide semiconductor may be amorphous (non-crystalline) or may have crystallinity. In the latter case, it may be a single crystal, a polycrystal, a structure in which a part has crystallinity, a structure including a crystalline part in the amorphous, or non-amorphous. As an example of a structure in which a part has crystallinity, an oxide semiconductor having a c-axis orientation and having a triangular or hexagonal atomic arrangement when viewed from a direction perpendicular to the ab plane, surface, or interface, and having metal atoms arranged in layers or metal atoms and oxygen atoms arranged in layers when viewed from a direction perpendicular to the c-axis, and including a crystal in which the orientation of the a-axis or b-axis is different (rotated around the c-axis) in the ab plane (CAAC-OS: C Axis Aligned Crystalline Oxide Semiconductor, also referred to as such) may be used. Also, the oxide semiconductor may be amorphous (non-crystalline) or may have crystallinity. In the latter case, it may be a single crystal, a polycrystal, a structure in which a part has crystallinity, a structure including a crystalline part in the amorphous, or non-amorphous. As an example of a structure in which a part has crystallinity, an oxide semiconductor having a c-axis orientation and having a triangular or hexagonal atomic arrangement when viewed from a direction perpendicular to the ab plane, surface, or interface, and having metal atoms arranged in layers or metal atoms and oxygen atoms arranged in layers when viewed from a direction perpendicular to the c-axis, and including a crystal in which the orientation of the a-axis or b-axis is different (rotated around the c-axis) in the ab plane (CAAC-OS: C Axis Aligned Crystalline Oxide Semiconductor, also referred to as such) may be used. Also, the oxide semiconductor may be amorphous (non-crystalline) or may have crystallinity. In the latter case, it may be a single crystal, a polycrystal, a structure in which a part has crystallinity, a structure including a crystalline part in the amorphous, or non-amorphous. As an example of a structure in which a part has crystallinity, an oxide semiconductor having a c-axis orientation and having a triangular or hexagonal atomic arrangement when viewed from a direction perpendicular to the ab plane, surface, or interface, and having metal atoms arranged in layers or metal atoms and oxygen atoms arranged in layers when viewed from a direction perpendicular to the c-axis, and including a crystal in which the orientation of the a-axis or b-axis is different (rotated around the c-axis) in the ab plane (CAAC-OS: C Axis Aligned Crystalline Oxide Semiconductor, also referred to as such) may be used. Also, the oxide semiconductor may be amorphous (non-crystalline) or may have crystallinity. In the latter case, it may be a single crystal, a polycrystal, a structure in which a part has crystallinity, a structure including a crystalline part in the amorphous, or non-amorphous. As an example of a structure in which a part has crystallinity, an oxide semiconductor having a c-axis orientation and having a triangular or hexagonal atomic arrangement when viewed from a direction perpendicular to the ab plane, surface, or interface, and having metal atoms arranged in layers or metal atoms and oxygen atoms arranged in layers when viewed from a direction perpendicular to the c-axis, and including a crystal in which the orientation of the a-axis or b-axis is different (rotated around the c-axis) in the ab plane (CAAC-OS: C Axis Aligned Crystalline Oxide Semiconductor, also referred to as such) may be used. Also, the oxide semiconductor may be amorphous (non-crystalline) or may have crystallinity. In the latter case, it may be a single crystal, a polycrystal, a structure in which a part has crystallinity, a structure including a crystalline part in the amorphous, or non-amorphous. As an example of a structure in which a part has crystallinity, an oxide semiconductor having a c-axis orientation and having a triangular or hexagonal atomic arrangement when viewed from a direction perpendicular to the ab plane, surface, or interface, and having metal atoms arranged in layers or metal atoms and oxygen atoms arranged in layers when viewed from a direction perpendicular to the c-axis, and including a crystal in which the orientation of the a-axis or b-axis is different (rotated around the c-axis) in the ab plane (CAAC-OS: C Axis Aligned Crystalline Oxide Semiconductor, also referred to as such) may be used. Also, the oxide semiconductor may be amorphous (non-crystalline) or may have crystallinity. In the latter case, it may be a single crystal, a polycrystal, a structure in which a part has crystallinity, a structure including a crystalline part in the amorphous, or non-amorphous. As an example of a structure in which a part has crystallinity, an oxide semiconductor having a c-axis orientation and having a triangular or hexagonal atomic arrangement when viewed from a direction perpendicular to the ab plane, surface, or interface, and having metal atoms arranged in layers or metal atoms and oxygen atoms arranged in layers when viewed from a direction perpendicular to the c-axis, and including a crystal in which the orientation of the a-axis or b-axis is different (rotated around the c-axis) in the ab plane (CAAC-OS: C Axis Aligned Crystalline Oxide Semiconductor, also referred to as such) may be used. Also, the oxide semiconductor may be amorphous (non-crystalline) or may have crystallinity. In the latter case, it may be a single crystal, a polycrystal, a structure in which a part has crystallinity, a structure including a crystalline part in the amorphous, or non-amorphous. As an example of a structure in which a part has crystallinity, an oxide semiconductor having a c-axis orientation and having a triangular or hexagonal atomic arrangement when viewed from a direction perpendicular to the ab plane, surface, or interface, and having metal atoms arranged in layers or metal atoms and oxygen atoms arranged in layers when viewed from a direction perpendicular to the c-axis, and including a crystal in which the orientation of the a-axis or b-axis is different (rotated around the c-axis) in the ab plane (CAAC-OS: C Axis Aligned Crystalline Oxide Semiconductor, also referred to as such) may be used. Also, the oxide semiconductor may be amorphous (non-crystalline) or may have crystallinity. In the latter case, it may be a single crystal, a polycrystal, a structure in which a part has crystallinity, a structure including a crystalline part in the amorphous, or non-amorphous. As an example of a structure in which a part has crystallinity, an oxide semiconductor having a c-axis orientation and having a triangular or hexagonal atomic arrangement when viewed from a direction perpendicular to the ab plane, surface, or interface, and having metal atoms arranged in layers or metal atoms and oxygen atoms arranged in layers when viewed from a direction perpendicular to the c-axis, and including a crystal in which the orientation of the a-axis or b-axis is different (rotated around the c-axis) in the ab plane (CAAC-OS: C Axis Aligned Crystalline Oxide Semiconductor, also referred to as such) may be used. Also, the oxide semiconductor may be amorphous (non-crystalline) or may have crystallinity. In the latter case, it may be a single crystal, a polycrystal, a structure in which a part has crystallinity, a structure including a crystalline part in the amorphous, or non-amorphous. As an example of a structure in which a part has crystallinity, an oxide semiconductor having a c-axis orientation and having a triangular or hexagonal atomic arrangement when viewed from a direction perpendicular to the ab plane, surface, or interface, and having metal atoms arranged in layers or metal atoms and oxygen atoms arranged in layers when viewed from a direction perpendicular to the c-axis, and including a crystal in which the orientation of the a-axis or b-axis is different (rotated around the c-axis) in the ab plane (CAAC-OS: C Axis Aligned Crystalline Oxide Semiconductor, also referred to as such) may be used.

[0102] CAAC-OS, in a broad sense, refers to an oxide that is not single-crystalline and has an atomic arrangement in the shape of a triangle, hexagon, equilateral triangle, or regular hexagon when viewed from a direction perpendicular to its ab plane, and contains a phase in which metal atoms are arranged in layers or metal atoms and oxygen atoms are arranged in layers when viewed from a direction perpendicular to the c-axis direction.

[0103] CAAC-OS is not a single crystal nor is it formed only from amorphous materials. Also, CAAC contains crystallized portions (crystalline portions), but in some cases, the boundaries between one crystalline portion and another cannot be clearly distinguished.

[0104] A part of the oxygen constituting CAAC-OS may be substituted with nitrogen. Also, the c-axes of the individual crystalline portions constituting CAAC-OS may be aligned in a certain direction (for example, a direction perpendicular to the substrate surface on which CAAC-OS is formed, the surface of CAAC-OS, etc.). Or, the normal lines of the ab planes of the individual crystalline portions constituting CAAC-OS may face a certain direction (for example, a direction perpendicular to the substrate surface on which CAAC-OS is formed, the surface of CAAC-OS, etc.).

[0105] Depending on its composition and the like, CAAC-OS can be a conductor, a semiconductor, or an insulator. Also, depending on its composition and the like, it can have translucency to visible light or not.

[0106] As an example of such CAAC-OS, an oxide that is formed in a film shape and has a triangular or hexagonal atomic arrangement when observed from a direction perpendicular to the film surface or the substrate surface on which the film is formed, and has a layered arrangement of metal atoms or metal atoms and oxygen atoms (or nitrogen atoms) when observing its film cross-section can also be cited. ​

[0107] An example of the crystal structure contained in CAAC-OS will be described in detail with reference to FIGS. 14 to 16. Unless otherwise specified, in FIGS. 14 to 16, the upward direction is the c-axis direction, and the plane orthogonal to the c-axis direction is the ab-plane. When simply referring to the upper half and the lower half, it means the upper half and the lower half with the ab-plane as the boundary. In FIG. 14, the O surrounded by a circle represents a 4-coordinate O, and the O surrounded by a double circle represents a 3-coordinate O.

[0108] FIG. 14(A) shows a structure having one 6-coordinate In and six 4-coordinate oxygen atoms (hereinafter referred to as 4-coordinate O) adjacent to the In. Here, the structure showing only the adjacent oxygen atoms for one metal atom is called a small group. The structure in FIG. 14(A) has an octahedral structure, but is shown as a planar structure for simplicity. Note that there are three 4-coordinate O each in the upper half and the lower half of FIG. 14(A). The small group shown in FIG. 14(A) has a charge of 0.

[0109] FIG. 14(B) shows a structure having one 5-coordinate Ga, three 3-coordinate oxygen atoms (hereinafter referred to as 3-coordinate O) adjacent to the Ga, and two 4-coordinate O adjacent to the Ga. All the 3-coordinate O are present on the ab-plane. There is one 4-coordinate O each in the upper half and the lower half of FIG. 14(B). Since In also has a 5-coordinate structure, the structure shown in FIG. 14(B) can be adopted. The small group shown in FIG. 14(B) has a charge of 0.

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

[0111] Fig. 14(D) shows a structure having one 6 - coordinate Sn and six 4 - coordinate Os adjacent to the Sn. There are three 4 - coordinate Os in the upper half of Fig. 14(D) and three 4 - coordinate 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 - coordinate O in the upper half of Fig. 14(E) and one 4 - coordinate 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 middle group, and an aggregate of a plurality of middle 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 - coordinate 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 - coordinate 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 - coordinate 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 - coordinate Os above the metal atom is equal to the number of adjacent metal atoms below that O, and similarly, the number of 4 - coordinate Os below the metal atom is equal to the number of adjacent The number of adjacent metal atoms is equal. Since O is 4 - coordinated, the sum of the number of adjacent metal atoms in the downward direction and the number of adjacent metal atoms in the upward direction is 4. Therefore, when the sum of the number of 4 - coordinated O atoms above a metal atom and the number of 4 - coordinated O atoms below another metal atom is 4, two small groups having metal atoms can be bonded to each other. For example, when a 6 - coordinated metal atom (In or Sn) is bonded through the 4 - coordinated O atoms in the lower half, since there are 3 4 - coordinated O atoms, it will bond to either a 5 - coordinated metal atom (Ga or In) or a 4 - coordinated metal atom (Zn). Metal atoms having these coordination numbers are bonded through 4 - coordinated O atoms in the c - axis direction. Also, in addition to this, a plurality of small groups are bonded so that the total charge of the layer structure becomes 0 to form a medium group. Fig. 15(A) shows a model diagram of the medium group constituting the layer structure of the In - Sn - Zn - based oxide. Fig. 15(B) shows a large group composed of three medium groups. Note that Fig. 15(C) shows the atomic arrangement when the layer structure of Fig. 15(B) is observed from the c - axis direction. In Fig. 15(A), for simplicity, 3 - coordinated O atoms are omitted, and only the number of 4 - coordinated O atoms is shown. For example, there are 3 4 - coordinated O atoms each in the upper half and the lower half of Sn, which is shown as 3 in the round frame. Similarly, in Fig. 15(A), there is 1 4 - coordinated O atom each in the upper half and the lower half of In, which is shown as 1 in the round frame. Also, similarly, in Fig. 15(A), there is 1 4 - coordinated O atom in the lower half and 3 4 - coordinated O atoms in the upper half. The number of adjacent metal atoms is equal. Since O is 4 - coordinated, the sum of the number of adjacent metal atoms in the downward direction and the number of adjacent metal atoms in the upward direction is 4. Therefore, when the sum of the number of 4 - coordinated O atoms above a metal atom and the number of 4 - coordinated O atoms below another metal atom is 4, two small groups having metal atoms can be bonded to each other. For example, when a 6 - coordinated metal atom (In or Sn) is bonded through the 4 - coordinated O atoms in the lower half, since there are 3 4 - coordinated O atoms, it will bond to either a 5 - coordinated metal atom (Ga or In) or a 4 - coordinated metal atom (Zn). Metal atoms having these coordination numbers are bonded through 4 - coordinated O atoms in the c - axis direction. Also, in addition to this, a plurality of small groups are bonded so that the total charge of the layer structure becomes 0 to form a medium group. Fig. 15(A) shows a model diagram of the medium group constituting the layer structure of the In - Sn - Zn - based oxide. Fig. 15(B) shows a large group composed of three medium groups. Note that Fig. 15(C) shows the atomic arrangement when the layer structure of Fig. 15(B) is observed from the c - axis direction.

[0115] In Fig. 15(A), for simplicity, 3 - coordinated O atoms are omitted, and only the number of 4 - coordinated O atoms is shown. For example, there are 3 4 - coordinated O atoms each in the upper half and the lower half of Sn, which is shown as 3 in the round frame. Similarly, in Fig. 15(A), there is 1 4 - coordinated O atom each in the upper half and the lower half of In, which is shown as 1 in the round frame. Also, similarly, in Fig. 15(A), there is 1 4 - coordinated O atom in the lower half and 3 4 - coordinated O atoms in the upper half. The number of adjacent metal atoms is equal. Since O is 4 - coordinated, the sum of the number of adjacent metal atoms in the downward direction and the number of adjacent metal atoms in the upward direction is 4. Therefore, when the sum of the number of 4 - coordinated O atoms above a metal atom and the number of 4 - coordinated O atoms below another metal atom is 4, two small groups having metal atoms can be bonded to each other. For example, when a 6 - coordinated metal atom (In or Sn) is bonded through the 4 - coordinated O atoms in the lower half, since there are 3 4 - coordinated O atoms, it will bond to either a 5 - coordinated metal atom (Ga or In) or a 4 - coordinated metal atom (Zn). Metal atoms having these coordination numbers are bonded through 4 - coordinated O atoms in the c - axis direction. Also, in addition to this, a plurality of small groups are bonded so that the total charge of the layer structure becomes 0 to form a medium group.

[0116] Fig. 15(A) shows a model diagram of the medium group constituting the layer structure of the In - Sn - Zn - based oxide. Fig. 15(B) shows a large group composed of three medium groups. Note that Fig. 15(C) shows the atomic arrangement when the layer structure of Fig. 15(B) is observed from the c - axis direction. In Fig. 15(A), for simplicity, 3 - coordinated O atoms are omitted, and only the number of 4 - coordinated O atoms is shown. For example, there are 3 4 - coordinated O atoms each in the upper half and the lower half of Sn, which is shown as 3 in the round frame. Similarly, in Fig. 15(A), there is 1 4 - coordinated O atom each in the upper half and the lower half of In, which is shown as 1 in the round frame. Also, similarly, in Fig. 15(A), there is 1 4 - coordinated O atom in the lower half and 3 4 - coordinated O atoms in the upper half. The number of adjacent metal atoms is equal. Since O is 4 - coordinated, the sum of the number of adjacent metal atoms in the downward direction and the number of adjacent metal atoms in the upward direction is 4. Therefore, when the sum of the number of 4 - coordinated O atoms above a metal atom and the number of 4 - coordinated O atoms below another metal atom is 4, two small groups having metal atoms can be bonded to each other. For example, when a 6 - coordinated metal atom (In or Sn) is bonded through the 4 - coordinated O atoms in the lower half, since there are 3 4 - coordinated O atoms, it will bond to either a 5 - coordinated metal atom (Ga or In) or a 4 - coordinated metal atom (Zn).

[0117] In Fig. 15(A), for simplicity, 3 - coordinated O atoms are omitted, and only the number of 4 - coordinated O atoms is shown. For example, there are 3 4 - coordinated O atoms each in the upper half and the lower half of Sn, which is shown as 3 in the round frame. Similarly, in Fig. 15(A), there is 1 4 - coordinated O atom each in the upper half and the lower half of In, which is shown as 1 in the round frame. Also, similarly, in Fig. 15(A), there is 1 4 - coordinated O atom in the lower half and 3 4 - coordinated O atoms in the upper half. The number of adjacent metal atoms is equal. Since O is 4 - coordinated, the sum of the number of adjacent metal atoms in the downward direction and the number of adjacent metal atoms in the upward direction is 4. Therefore, when the sum of the number of 4 - coordinated O atoms above a metal atom and the number of 4 - coordinated O atoms below another metal atom is 4, two small groups having metal atoms can be bonded to each other. For example, when a 6 - coordinated metal atom (In or Sn) is bonded through the 4 - coordinated O atoms in the lower half, since there are 3 4 - coordinated O atoms, it will bond to either a 5 - coordinated metal atom (Ga or In) or a 4 - coordinated metal atom (Zn). Metal atoms having these coordination numbers are bonded through 4 - coordinated O atoms in the c - axis direction. Also, in addition to this, a plurality of small groups are bonded so that the total charge of the layer structure becomes 0 to form a medium group. Fig. 15(A) shows a model diagram of the medium group constituting the layer structure of the In - Sn - Zn - based oxide. Fig. 15(B) shows a large group composed of three medium groups. Note that Fig. 15(C) shows the atomic arrangement when the layer structure of Fig. 15(B) is observed from the c - axis direction. In Fig. 15(A), for simplicity, 3 - coordinated O atoms are omitted, and only the number of 4 - coordinated O atoms is shown. For example, there are 3 4 - coordinated O atoms each in the upper half and the lower half of Sn, which is shown as 3 in the round frame. Similarly, in Fig. 15(A), there is 1 4 - coordinated O atom each in the upper half and the lower half of In, which is shown as 1 in the round frame. Also, similarly, in Fig. 15(A), there is 1 4 - coordinated O atom in the lower half and 3 4 - coordinated O atoms in the upper half. Zn with one four-coordinated O in the upper half and three four-coordinated O in the lower half is shown.

[0118] In Fig. 15(A), the middle group constituting the layer structure of the In-Sn-Zn oxide system has, from the top in order, Sn with three four-coordinated O in both the upper and lower halves, In with one four-coordinated O in both the upper and lower halves bonded to the In, the In bonded to Zn with three four-coordinated O in the upper half, and through one four-coordinated O in the lower half of the Zn, four-coordinated O are bonded to In with three four-coordinated O in both the upper and lower halves the In bonded to Zn with one four-coordinated O in the upper half, and the In bonded to a small group consisting of two Zn through one four-coordinated O in the lower half of this small group, and four-coordinated O are bonded to Sn with three four-coordinated O in both the upper and lower halves. This is the structure where this middle group is multiply bonded to form a large group. Here, in the case of three-coordinated O and four-coordinated O, the charge per bond can be considered to be -0.6 67 and -0.5 respectively. For example, the charges of In (6-coordinated or 5-coordinated), Zn (4 coordinated), Sn (5-coordinated or 6-coordinated) are +3, +2, +4 respectively. Therefore, the small group containing Sn has a charge of +1. So, in order to form a layer structure containing Sn

[0119] a charge of -1 to cancel out the charge +1 is required. As a structure with a charge of -1, as shown in Fig. 1 4(E), a small group containing two Zn can be mentioned. For example, if there is one small group containing Sn and one small group containing two Zn, the charges are cancelled out, and the total charge of the layer structure can be made 0.

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

[0121] In addition to this, there are also In-Sn-Ga-Zn system oxides which are quaternary metal oxides, and tri 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 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 and the like are the same when used.

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

[0123] In Fig. 16(A), the middle group constituting the layer structure of the In-Ga-Zn system oxide is the upper ​In with three 4-coordinated O atoms each in the upper and lower halves in order from the top is bonded to Zn with one 4-coordinated O atom in the upper half, and through the three 4-coordinated O atoms in the lower half of the Zn, it is bonded to Ga with one 4-coordinated O atom each in the upper and lower halves, and through the one 4-coordinated O atom in the lower half of the Ga, it is bonded to In with three 4-coordinated O atoms each in the upper and lower halves. A structure in which multiple of these groups are bonded to form a large group. Figure 16(B) shows a large group composed of three middle groups. Note that Figure 16(C) shows the atomic arrangement when observing the layer structure of Figure 16(B) from the c-axis direction. Here, since the charges of In (6-coordinated or 5-coordinated), Zn (4-coordinated), and Ga (5-coordinated) are +3, +2, and +3 respectively, a small group containing any of In, Zn, and Ga has a charge of 0. Therefore, for any combination of these small groups, the total charge of the middle group is always 0. Also, the middle groups constituting the layer structure of the In-Ga-Zn-based oxide are not limited to the middle groups shown in Figure 16(A), and large groups combined with middle groups having different arrangements of In, Ga, and Zn are also possible.

[0124] Specifically, by repeating the large group shown in Figure 16(B), a crystal of the In-Ga-Zn-based oxide can be obtained. The layer structure of the obtained In-Ga-Zn-based oxide can be represented by the composition formula InGaO3(ZnO)n (n is a natural number). This embodiment can be implemented in combination with other embodiments.

[0125] Here, since the charges of In (6-coordinated or 5-coordinated), Zn (4-coordinated), and Ga (5-coordinated) are +3, +2, and +3 respectively, a small group containing any of In, Zn, and Ga has a charge of 0. Therefore, for any combination of these small groups, the total charge of the middle group is always 0. Also, the middle groups constituting the layer structure of the In-Ga-Zn-based oxide are not limited to the middle groups shown in Figure 16(A), and large groups combined with middle groups having different arrangements of In, Ga, and Zn are also possible. Specifically, by repeating the large group shown in Figure 16(B), a crystal of the In-Ga-Zn-based oxide can be obtained. The layer structure of the obtained In-Ga-Zn-based oxide can be represented by the composition formula InGaO3(ZnO)n (n is a natural number). This embodiment can be implemented in combination with other embodiments.

[0126] Also, the middle groups constituting the layer structure of the In-Ga-Zn-based oxide are not limited to the middle groups shown in Figure 16(A), and large groups combined with middle groups having different arrangements of In, Ga, and Zn are also possible. Specifically, by repeating the large group shown in Figure 16(B), a crystal of the In-Ga-Zn-based oxide can be obtained. The layer structure of the obtained In-Ga-Zn-based oxide can be represented by the composition formula InGaO3(ZnO)n (n is a natural number). This embodiment can be implemented in combination with other embodiments.

[0127] Specifically, by repeating the large group shown in Figure 16(B), a crystal of the In-Ga-Zn-based oxide can be obtained. The layer structure of the obtained In-Ga-Zn-based oxide can be represented by the composition formula InGaO3(ZnO)n (n is a natural number). This embodiment can be implemented in combination with other embodiments. InGaO3(ZnO) n (n is a natural number.)

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

[0129] (Embodiment 3) In a light-emitting device according to an aspect of the present invention, a light-emitting element that emits single-color light such as white light and a color filter are combined to display a full-color image, and a color filter method is adopted to do. Alternatively, a method of displaying a full-color image can be adopted using a plurality of light-emitting elements that emit light of different hues. This method is called the coating method because the EL layer provided between a pair of electrodes of the light-emitting element is painted for each corresponding color.

[0130] In the case of the coating method, the coating of the EL layer is usually performed by a vapor deposition method using a mask such as a metal mask. Therefore, the size of the pixel depends on the coating accuracy of the EL layer by the vapor deposition method. On the other hand, in the case of the color filter method, unlike the coating method, it is not necessary to coat the EL layer. Therefore, it is easier to reduce the pixel size than in the case of the coating method, and a high-definition pixel portion can be realized.

[0131] In addition, the light-emitting device includes a substrate on which a transistor is formed, a bottom emission structure that extracts the light of the light-emitting element from the so-called element substrate side, and a top emission structure that extracts the light of the light-emitting element from the side opposite to the element substrate. In the case of the top emission structure, the light emitted from the light-emitting element is not blocked by various elements such as wiring, transistors, and holding capacitors. Therefore, the light extraction efficiency from the pixel can be increased compared to the bottom emission structure. Therefore, the top emission structure is advantageous for extending the life of the light-emitting element because high luminance can be obtained even when the current value supplied to the light-emitting element is kept low.

[0132] In the light-emitting device according to one embodiment of the present invention, the light emitted from the EL layer is resonated in the light-emitting element. The light source may have a microcavity (micro-optical resonator) structure. The Tee structure can increase the extraction efficiency of light of a specific wavelength from the light-emitting element. Therefore, the brightness and color purity of the pixel portion can be improved.

[0133] FIG. 10 shows a cross-sectional view of a pixel as an example. Note that FIG. 10 shows a cross-sectional view of a pixel corresponding to red. A part of the surface, a part of the cross section of the pixel corresponding to blue, and a part of the cross section of the pixel corresponding to green are shown. There are.

[0134] Specifically, in FIG. 10, a pixel 140r corresponding to red, a pixel 140g corresponding to green, and Pixels 140r, 140g, and 140b are shown. The anodes 715r, 715g, and 715b are respectively provided. The anode 715g and the anode 715b are connected to the pixel 140r, the pixel 140g, and the pixel 140b, respectively. 7, it is provided on an insulating film 750 formed on a substrate 740.

[0135] A partition wall 73 having an insulating film is formed on the anode 715r, the anode 715g, and the anode 715b. The partition wall 730 has an opening, and the anode 715r, The anode 715g and the anode 715b are each partially exposed. The EL layer 731 and a transparent layer having a visible light transmitting property are provided on the partition 730 so as to cover the region. A cathode 732 is laminated in this order.

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

[0137] Also, the substrate 742 faces the substrate 740 so as to sandwich the light-emitting element 741r, the light-emitting element 741g, and the light-emitting element 741b therebetween. On the substrate 742, a coloring layer 743r corresponding to the pixel 140r, a coloring layer 743g corresponding to the pixel 140g, and a coloring layer 743b corresponding to the pixel 140b are provided. The coloring layer 743r is a layer having a higher transmittance of light in the wavelength region corresponding to red than the transmittance of light in other wavelength regions. The coloring layer 743g is a layer having a higher transmittance of light in the wavelength region corresponding to green than the transmittance of light in other wavelength regions. The coloring layer 743b is a layer having a higher transmittance of light in the wavelength region corresponding to blue than the transmittance of light in other wavelength regions. Furthermore, an overcoat 744 is provided on the substrate 742 so as to cover the coloring layer 743r, the coloring layer 743g, and the coloring layer 743b. The overcoat 744 is a layer having light transmittance with respect to visible light for protecting the coloring layer 743r, the coloring layer 743g, and the coloring layer 743b, and it is preferable to use a resin material with high flatness. The coloring layer 743r, the coloring layer 743g, and the coloring layer 743b together with the overcoat 744 may be regarded as a color filter, or each of the coloring layer 743r, the coloring layer 743g, and the coloring layer 743b may be regarded as a color filter. And in FIG. 10, a conductive film 745r having a high reflectance of visible light and visible light are provided on the anode 715r. is provided on the anode 715r. is provided on the anode 715r. is provided on the anode 715r.

[0138] are provided on the anode 715r. are provided on the anode 715r. are provided on the anode 715r. are provided on the anode 715r. are provided on the anode 715r. are provided on the anode 715r. are provided on the anode 715r.

[0139] And in FIG. 10, a conductive film 745r having a high reflectance of visible light and visible light A conductive film 746r having a transmittance higher than that of the conductive film 745r is sequentially laminated and used. Also, on the anode 715g, a conductive film 745g having a high reflectance of visible light and a conductive film 746g having a transmittance of visible light higher than that of the conductive film 745g are sequentially laminated and used. The film thickness of the conductive film 746g is made smaller than the film thickness of the conductive film 746r. Further, a conductive film 745b having a high reflectance of visible light is used for the anode 715b. Therefore, in the light-emitting device shown in FIG. 10, in the light-emitting element 741r, the optical path length of the light emitted from the EL layer 731 can be adjusted by the distance between the conductive film 745r and the cathode 732. Also, in the light-emitting element 741g, the optical path length of the light emitted from the EL layer 731 can be adjusted by the distance between the conductive film 7

[0140] 45g and the cathode 732. Also, in the light-emitting element 741b, the optical path length of the light emitted from the EL layer 731 can be adjusted by the distance between the conductive film 745b and the cathode 732. Therefore, in the light-emitting element 741b, the optical path length of the light emitted from the EL layer 731 can be adjusted by the distance between the conductive film 745b and the cathode 732. Also, in the light-emitting element 741g, the optical path length of the light emitted from the EL layer 731 can be adjusted by the distance between the conductive film 7 45g and the cathode 732. Also, in the light-emitting element 741b, the optical path length of the light emitted from the EL layer 731 can be adjusted by the distance between the conductive film 745b and the cathode 732. Therefore, in the light-emitting element 741b, the optical path length of the light emitted from the EL layer 731 can be adjusted by the distance between the conductive film 745b and the cathode 732. Therefore, in the light-emitting element 741b, the optical path length of the light emitted from the EL layer 731 can be adjusted by the distance between the conductive film 745b and the cathode 732.

[0141] In one aspect of the present invention, by adjusting the optical path length in accordance with the wavelengths of the light corresponding to the light-emitting element 741r, the light-emitting element 741g, and the light-emitting element 741b, respectively, a microcavity structure that resonates the light emitted from the EL layer 731 within each of the above light-emitting elements may be used. By adopting the above microcavity structure in the light-emitting device according to one aspect of the present invention, in the light emitted from the light-emitting element 741r, the intensity of the light having a wavelength corresponding to red is increased by resonance. Therefore, the color purity and luminance of the red light obtained through the coloring layer 743r are increased. Also, in the light emitted from the light-emitting element 741g, the intensity of the light having a wavelength corresponding to green is increased.

[0142] By adopting the above microcavity structure in the light-emitting device according to one aspect of the present invention, in the light emitted from the light-emitting element 741r, the intensity of the light having a wavelength corresponding to red is increased by resonance. Therefore, the color purity and luminance of the red light obtained through the coloring layer 743r are increased. Also, in the light emitted from the light-emitting element 741g, the intensity of the light having a wavelength corresponding to green is increased by resonance. Therefore, the color purity and luminance of the green light obtained through the coloring layer 743g are increased. is increased. Therefore, the color purity and luminance of the green light obtained through the coloring layer 743g are increased. The degree is enhanced by resonance. Therefore, the color purity and luminance of the green light obtained through the coloring layer 743g are enhanced. Also, in the light emitted from the light-emitting element 741b, the intensity of the light having a wavelength corresponding to blue is enhanced by resonance. Therefore, the color purity and luminance of the blue light obtained through the coloring layer 743b are enhanced.

[0143] In FIG. 10, a configuration using pixels corresponding to three colors of red, green, and blue is shown, but in one aspect of the present invention, the configuration is not limited thereto. The combination of colors used in one aspect of the present invention is , for example, four colors of red, green, blue, and yellow, or three colors of cyan, magenta, and yellow may be used. Alternatively, the combination of the above colors may be six colors of light red, green, and blue, and dark red, green, and blue. Alternatively, the combination of the above colors may be six colors of red, green, blue, cyan, magenta, and yellow.

[0144] Note that, for example, the colors that can be expressed using pixels of red, green, and blue are limited to the colors shown inside the triangle drawn by three points corresponding to the respective emission colors on the chromaticity diagram. Therefore, by adding separately a light-emitting element having an emission color existing outside the triangle on the chromaticity diagram as in the case of using pixels of red, green, blue, and yellow, the color gamut that can be expressed in the light-emitting device can be expanded, and the color reproducibility can be enriched.

[0145] Also, in FIG. 10, among the light-emitting elements 741r, 741g, and 741b, in the light-emitting element 741b having the shortest light wavelength λ, a conductive film 745b having a high reflectance of visible light is used as the anode, and in the other light-emitting elements 741r and 741g, the film thicknesses are different from each other. ​​​​​​​​By using the conductive film 746r and the conductive film 746g, the optical path length is adjusted. In this invention, in one aspect, even in the light-emitting element 741b with the shortest wavelength λ, the reflectance of visible light is high On the conductive film 745b, a conductive film with a high transmittance of visible light, such as the conductive film 746r and the conductive film 746g, may be provided. However, as shown in FIG. 10, when the conductive film 745b with a high reflectance of visible light constitutes the anode in the light-emitting element 741b with the shortest wavelength λ, in all In the light-emitting elements, when using a conductive film with a high transmittance of visible light for the anode, the manufacturing process of the anode is simplified compared to the case where a conductive film with a high transmittance of visible light is used for the anode in all light-emitting elements, so it is preferable. The manufacturing process of the anode is simplified, so it is preferable. For the conductive film 745b with a high reflectance of visible light, the work function is often smaller than that of the conductive film 746r and the conductive film 746g with a high transmittance of visible light. Therefore, in the light-emitting element 741b with the shortest wavelength λ of light, compared with the light-emitting elements 741r and 741g, the injection of holes from the anode 715b

[0146] to the EL layer 731 is difficult, so the luminous efficiency tends to be low. Therefore, in one aspect of the present invention, in the light-emitting element 741b with the shortest wavelength λ of light, in the layer of the EL layer 731 that is in contact with the conductive film 745b with a high reflectance of visible light, a substance with high hole transportability is preferably used, and a composite material containing a substance that exhibits acceptor properties (electron-accepting properties) with respect to the substance with high hole transportability is used. By forming the above composite material in contact with the anode 715b The injection of holes from the anode 715b to the EL layer 731 becomes easier, and the luminous efficiency of the light-emitting element 741b can be increased. For the conductive film 745b with a high reflectance of visible light, the work function is often smaller than that of the conductive film 746r and the conductive film 746g with a high transmittance of visible light. Therefore, in the light-emitting element 741b with the shortest wavelength λ of light, compared with the light-emitting elements 741r and 741g, the injection of holes from the anode 715b to the EL layer 731 is difficult, so the luminous efficiency tends to be low. Therefore, in one aspect of the present invention, in the light-emitting element 741b with the shortest wavelength λ of light, in the layer of the EL layer 731 that is in contact with the conductive film 745b with a high reflectance of visible light, a substance with high hole transportability is preferably used, and a composite material containing a substance that exhibits acceptor properties (electron-accepting properties) with respect to the substance with high hole transportability is used. By forming the above composite material in contact with the anode 715b The injection of holes from the anode 715b to the EL layer 731 becomes easier, and the luminous efficiency of the light-emitting element 741b can be increased. The injection of holes from the anode 715b to the EL layer 731 becomes easier, and the luminous efficiency of the light-emitting element 741b can be increased. For the conductive film 745b with a high reflectance of visible light, the work function is often smaller than that of the conductive film 746r and the conductive film 746g with a high transmittance of visible light. Therefore, in the light-emitting element 741b with the shortest wavelength λ of light, compared with the light-emitting elements 741r and 741g, the injection of holes from the anode 715b to the EL layer 731 is difficult, so the luminous efficiency tends to be low. Therefore, in one aspect of the present invention, in the light-emitting element 741b with the shortest wavelength λ of light, in the layer of the EL layer 731 that is in contact with the conductive film 745b with a high reflectance of visible light, a substance with high hole transportability is preferably used, and a composite material containing a substance that exhibits acceptor properties (electron-accepting properties) with respect to the substance with high hole transportability is used. By forming the above composite material in contact with the anode 715b The injection of holes from the anode 715b to the EL layer 731 becomes easier, and the luminous efficiency of the light-emitting element 741b can be increased.

[0147] Examples of the substance that exhibits acceptor properties include 7,7,8,8-tetracyano-2,3,5,6- Examples include tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, etc. Transition metal oxides can also be mentioned. Oxides of metals belonging to Groups 4 to 8 in the periodic table of elements can also be mentioned. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide are preferable because of their high acceptor properties. Among them, molybdenum oxide is particularly preferable because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle. Examples of substances with high hole transport properties used in composite materials include aromatic amine compounds, carbazole derivatives, aromatic hydrocarbons, polymer compounds (such as oligomers, dendrimers, polymers, etc.). Various compounds can be used. Note that as the organic compound used in the composite material, it is preferably an organic compound with high hole transport properties. Specifically, it is preferably a substance having a hole mobility of 10 cm / Vs or more. However, as long as it is a substance with higher hole transport properties than electrons, other substances may be used. In addition, as the conductive films 745r, 745g, and 745b with high visible light reflectivity, for example, aluminum, silver, or an alloy containing these metal materials can be formed by a single layer or by laminating them. Also, the conductive films 745r, 745g, and 745b can be formed by laminating a conductive film with high visible light reflectivity and a conductive film with a thin film thickness (preferably 20 nm or less, more preferably 10 nm or less). For example, a thin titanium film or molybdenum film can be laminated on a conductive film with high visible light reflectivity to form the conductive film 745b.

[0148] Examples include tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, etc. Transition metal oxides can also be mentioned. Oxides of metals belonging to Groups 4 to 8 in the periodic table of elements can also be mentioned. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide are preferable because of their high acceptor properties. Among them, molybdenum oxide is particularly preferable because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle. Examples of substances with high hole transport properties used in composite materials include aromatic amine compounds, carbazole derivatives, aromatic hydrocarbons, polymer compounds (such as oligomers, dendrimers, polymers, etc.). Various compounds can be used. Note that as the organic compound used in the composite material, it is preferably an organic compound with high hole transport properties. Specifically, it is preferably a substance having a hole mobility of 10 cm / Vs or more. However, as long as it is a substance with higher hole transport properties than electrons, other substances may be used. -6 cm 2 / Vs or more. However, as long as it is a substance with higher hole transport properties than electrons, other substances may be used. Examples include tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, etc. Transition metal oxides can also be mentioned. Oxides of metals belonging to Groups 4 to 8 in the periodic table of elements can also be mentioned. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide are preferable because of their high acceptor properties. Among them, molybdenum oxide is particularly preferable because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle. Examples of substances with high hole transport properties used in composite materials include aromatic amine compounds, carbazole derivatives, aromatic hydrocarbons, polymer compounds (such as oligomers, dendrimers, polymers, etc.). Various compounds can be used. Note that as the organic compound used in the composite material, it is preferably an organic compound with high hole transport properties. Specifically, it is preferably a substance having a hole mobility of 10

[0149] In addition, as the conductive films 745r, 745g, and 745b with high visible light reflectivity, for example, aluminum, silver, or an alloy containing these metal materials can be formed by a single layer or by laminating them. Also, the conductive films 745r, 745g, and 745b can be formed by laminating a conductive film with high visible light reflectivity and a conductive film with a thin film thickness (preferably 20 nm or less, more preferably 10 nm or less). For example, a thin titanium film or molybdenum film can be laminated on a conductive film with high visible light reflectivity to form the conductive film 745b. Examples include tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, etc. Transition metal oxides can also be mentioned. Oxides of metals belonging to Groups 4 to 8 in the periodic table of elements can also be mentioned. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide are preferable because of their high acceptor properties. Among them, molybdenum oxide is particularly preferable because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle. Examples of substances with high hole transport properties used in composite materials include aromatic amine compounds, carbazole derivatives, aromatic hydrocarbons, polymer compounds (such as oligomers, dendrimers, polymers, etc.). Various compounds can be used. Note that as the organic compound used in the composite material, it is preferably an organic compound with high hole transport properties. Specifically, it is preferably a substance having a hole mobility of 10 cm / Vs or more. However, as long as it is a substance with higher hole transport properties than electrons, other substances may be used. By forming it, it is possible to prevent the formation of an oxide film on the surface of a conductive film (such as aluminum, an alloy containing aluminum, or silver) with a high reflectance of visible light. It is possible to prevent the formation of an oxide film on the surface of a conductive film (such as aluminum, an alloy containing aluminum, or silver) with a high reflectance of visible light.

[0150] In addition, for the conductive film 746r and the conductive film 746g with a high transmittance of visible light, for example, indium oxide, tin oxide, zinc oxide, indium tin oxide, indium zinc oxide, etc. can be used. It is possible.

[0151] In addition, the cathode 732 can be formed, for example, by laminating a thin conductive film (preferably 20 nm or less, more preferably 10 nm or less) that transmits light and a conductive film composed of a conductive metal oxide. The thin conductive film that transmits light can be formed of silver, magnesium, or an alloy containing these metal materials, either as a single layer or by lamination. As the conductive metal oxide, indium oxide, tin oxide, zinc oxide, indium tin oxide, indium zinc oxide, or a material obtained by including silicon oxide in these metal oxide materials can be used. It is possible. oxide, indium zinc oxide, or a material obtained by including silicon oxide in these metal oxide materials can be used. It is possible.

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

[0153] (Embodiment 4) In this embodiment, the bottom emission structure, the top emission structure, and the dual emission structure will be described. The dual emission structure means a structure in which the light of the light-emitting element is taken out from the element substrate side and from the side opposite to the element substrate. It means a structure in which the light of the light-emitting element is taken out from the element substrate side and from the side opposite to the element substrate.

[0154] In FIG. 11(A), when the light emitted from the light-emitting element 6033 is taken out from the anode 6034 side shows a cross-sectional view of a pixel. The transistor 6031 is covered with an insulating film 6037, and a partition wall 6038 having an opening is formed on the insulating film 6037. A part of the anode 6034 is exposed in the opening of the partition wall 6038, and the anode 6034, the EL layer 60 35, and the cathode 6036 are laminated in this order in the opening. The anode 6034 is formed of a material or film thickness that easily transmits light, and the cathode 6036 is formed of a material or film thickness that hardly transmits light. With the above configuration, a bottom emission structure that extracts light as indicated by the white arrow from the anode 6034 side can be obtained.

[0155] The anode 6034 is formed of a material or film thickness that easily transmits light, and the cathode 6036 is formed of a material or film thickness that hardly transmits light. With the above configuration, a bottom emission structure that extracts light as indicated by the white arrow from the anode 6034 side can be obtained. The anode 6034 is formed of a material or film thickness that easily transmits light, and the cathode 6036 is formed of a material or film thickness that hardly transmits light. With the above configuration, a bottom emission structure that extracts light as indicated by the white arrow from the anode 6034 side can be obtained. As shown by the white arrow from the anode 6034 side, a bottom emission structure that extracts light can be obtained.

[0156] Fig. 11(B) shows a cross-sectional view of a pixel when the light emitted from the light-emitting element 6043 is extracted from the cathode 6046 side. The transistor 6041 is covered with an insulating film 6047, and a partition wall 6048 having an opening is formed on the insulating film 6047. A part of the anode 6044 is exposed in the opening of the partition wall 6048, and the anode 6044, the EL layer 60 45, and the cathode 6046 are laminated in this order in the opening. In the opening of the partition wall 6048, a part of the anode 6044 is exposed, and the anode 6044, the EL layer 60 45, and the cathode 6046 are laminated in this order in the opening.

[0157] The anode 6044 is formed of a material or film thickness that hardly transmits light, and the cathode 6046 is formed of a material or film thickness that easily transmits light. With the above configuration, a top emission structure that extracts light as indicated by the white arrow from the cathode 6046 side can be obtained. The anode 6044 is formed of a material or film thickness that hardly transmits light, and the cathode 6046 is formed of a material or film thickness that easily transmits light. With the above configuration, a top emission structure that extracts light as indicated by the white arrow from the cathode 6046 side can be obtained. As shown by the white arrow from the cathode 6046 side, a top emission structure that extracts light can be obtained.

[0158] Fig. 11(C) shows a cross-sectional view of a pixel when the light emitted from the light element 6053 is extracted from the anode 6054 side and the cathode 6056 side. The transistor 6051 is covered with an insulating film 6057, and a partition wall 6058 having an opening is formed on the insulating film 6057. A partition wall 6058 having an opening is formed on the insulating film 6057. film 6057, and a partition wall 6058 having an opening is formed on the insulating film 6057. The partition In the opening of 6058, part of the anode 6054 is exposed, and in this opening, the anode 60 54, the EL layer 6055, and the cathode 6056 are laminated in this order.

[0159] The anode 6054 and the cathode 6056 are formed of a material or film thickness that easily transmits light. With the above structure, light is extracted as shown by the white arrows from the anode 6054 and cathode 6056 sides, and a dual emission structure can be obtained.

[0160] Note that as the electrode that becomes the anode or cathode, metals, alloys, electrically conductive compounds, and mixtures thereof can be used. Specifically, indium tin oxide (ITO: Indium Tin Oxide), indium tin oxide containing silicon or silicon oxide, indium zinc oxide, indium oxide containing tungsten and zinc, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), titanium (Ti), and in addition, elements belonging to Group 1 or Group 2 of the periodic table, that is, alkali metals such as lithium (Li) and cesium (Cs), and alkaline earth metals such as calcium (Ca) and strontium (Sr), magnesium (Mg), and alloys containing these (MgAg, AlLi), rare earth metals such as europium (Eu) and ytterbium (Yb) and alloys containing these, and others, such as graphene, can be used. Then, by appropriately selecting the above materials and setting their film thicknesses to optimal values, a bottom emission structure, a top emission structure, or a dual emission structure can be obtained. emission structure can be obtained. It is possible to create different al-emission structures.

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

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

[0163] The light emitting device shown in FIG. 12 includes a panel 1601, a circuit board 1602, and a connection portion 1603. The panel 1601 has a pixel portion 1604 having a plurality of pixels, and A scanning line driver circuit 1605 for selecting each row and inputting image signals to pixels in the selected row Specifically, the scanning line driver circuit 1605 includes: , and generates signals to be input to the wirings G1 to G3.

[0164] Various signals and a power supply potential are transmitted from the circuit board 1602 to the panel via the connection portion 1603. The connection part 1603 is connected to an FPC (Flexible Printer d Circuit) can be used. Also, COF tape can be used for the connection part 1603. In the case of using a scanning line of a part of the circuit board 1602 or the panel 1601, A driver circuit 1605 and a part of a signal line driver circuit 1606 are formed on a separately prepared chip. Then, the chip is connected to the COF tape using the COF (Chip On Film) method. It's fine to keep it that way.

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

[0166] (Embodiment 6) The light-emitting device according to one aspect of the present invention includes a display device, a personal computer, and a recording medium and can be used in an image playback device (typically a device having a display that can play a recording medium such as a DVD: Digital Versatile Disc and display the image). In addition, as electronic devices that can use the light-emitting device according to one aspect of the present invention , there are mobile phones, game machines including portable types, portable information terminals, e-books, video cameras, digital still cameras, goggle-type displays (head-mounted displays), navigation systems, audio playback devices (such as car audio, digital audio players, etc.), copiers , facsimiles, printers, printer multifunction devices, automated teller machines (ATMs) , vending machines, and the like. Specific examples of these electronic devices are shown in FIG. 13.

[0167] FIG. 13(A) is a portable game machine, which has a housing 5001, a housing 5002, a display unit 5003, a display unit 5004, a microphone 5005, a speaker 5006, operation keys 5007, a start illustration 5008, and the like. The light-emitting device according to one aspect of the present invention can be used for the display unit 5003 and the display unit 5004. By using the light-emitting device according to one aspect of the present invention for the display unit 5003 or the display unit 5004, a high-quality portable game machine can be provided. Note that although the portable game machine shown in FIG. 13(A) has two display units 5003 and 5004, the number of display units of the portable game machine is not limited to this.

[0168] FIG. 13(B) is a display device, which has a housing 5201, a display unit 5202, a support base 5203, and the like. The light-emitting device according to one aspect of the present invention can be used for the display unit 5202. The display unit By using the light-emitting device according to one aspect of the present invention in 5202, a display device with high image quality can be provided. The display device includes all information display devices such as those for personal computers, TV broadcast reception, and advertisement display.

[0169] Figure 13(C) is a notebook personal computer, which has a housing 5401, a display unit 5402 , a keyboard 5403, a pointing device 5404, etc. The light-emitting device according to one aspect of the present invention can be used for the display unit 5402. By using the light-emitting device according to one aspect of the present invention in the display unit 5402 , a notebook personal computer with high image quality can be provided.

[0170] Figure 13(D) is a portable information terminal, which has a housing 5601, a display unit 5602, operation keys 5603 , etc. In the portable information terminal shown in Figure 13(D), a modem may be built in the housing 5601 . The light-emitting device according to one aspect of the present invention can be used for the display unit 5602. By using the light-emitting device according to one aspect of the present invention in the display unit 5602 , a portable information terminal with high image quality can be provided.

[0171] Figure 13(E) is a mobile phone, which has a housing 5801, a display unit 5802, a voice input unit 5803, a voice output unit 5804, operation keys 5805, a light receiving unit 5806, etc. By converting the light received at the light receiving unit 5806 into an electrical signal, an external image can be captured. The light-emitting device according to one aspect of the present invention can be used for the display unit 5802. By using the light-emitting device according to one aspect of the present invention in the display unit 5802 , a mobile phone with high image quality can be provided.

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

[0173] (Embodiment 7) In this embodiment, the operation of the pixel 100 shown in FIG. 1(A) described in Embodiment 1 in period 3, the value of the gate voltage Vgs of the transistor 11 was obtained by simulation .

[0174] The simulation was performed using condition A or condition B in which the values of the potential V0 in the wiring IL are different from each other. Specifically, the values of the potential of each wiring in condition A and condition B are shown in Table 1 below . The potential GVDD corresponds to the high level potential applied to the wirings G1, G2, and G3, respectively. Also, the potential GVSS corresponds to the low level potential applied to the wirings G1, G2, and G3, respectively. In Table 1, the potential Vcat is set to 0 V , and the values of the potential Vdata, potential Vano, potential V0, potential GVDD, and potential GVSS are shown as the potential difference from the potential Vcat.

[0175]

Table 1

[0176] Also, the ratio of the channel length L to the channel width W of each transistor in the simulation is L / W = 9 μm / 3 μm for the transistor 11, and L / W = 3 μm / 3 μm for the transistors 12 to 15 . And in all the transistors of the pixel 100 shown in FIG. 1(A), when the region where the conductive film functioning as the source or drain is in contact with the semiconductor film is defined as region A, the above region A and the region where the gate electrode is formed are in contact. When the region where the conductive film functioning as the source or drain is in contact with the semiconductor film is defined as region A, the above region A and the region where the gate electrode is formed In the overlapping region, the channel length direction length (Lov) was set to 1.5 μm.

[0177] In period 3, the gate voltage Vgs of transistor 11 becomes the voltage Vdata - V0 + Vth as shown in Fig. 3(C). Therefore, in pixel 100 shown in Fig. 1(A), since Vgs - Vth = Vdata - V0, Vgs - Vth ideally has a constant value regardless of the value of the threshold voltage Vth.

[0178] Fig. 17 shows the value of Vgs - Vth obtained by simulation when condition A is used. In Fig. 17, the horizontal axis represents the threshold voltage Vth (V), and the vertical axis represents the value of Vgs - Vth (V). In Fig. 17, it can be seen that even when the value of the threshold voltage Vth is changed, the value of Vgs - Vth is almost uniform, and its variation is suppressed to about 25% - 30%.

[0179] Fig. 18 shows the value of Vgs - Vth obtained by simulation when condition B is used. In Fig. 18, the horizontal axis represents the threshold voltage Vth (V), and the vertical axis represents the value of Vgs - Vth (V). In Fig. 18, when the value of the threshold voltage Vth has a positive value, the value of Vgs - Vth is uniform. However, when the value of the threshold voltage Vth has a negative value, as the value of the threshold voltage Vth becomes more negative, the value of Vgs - Vth increases, indicating that the value of Vgs - Vth depends on the value of 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, even when transistor 1 1 is in the normally-on state, that is, even when the threshold voltage Vth has a negative value, ​​​​​​The gate of the transistor 11 can be set to a value taking into account the threshold voltage Vth of the transistor 11. It has been proven that the gate voltage Vgs of the transistor 11 can be set.

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

Description of Reference Numerals

[0182] 11 Transistor 12 Transistor 13 Transistor 14 Transistor 15 Transistor 16 Capacitor element 17 Light-emitting element 100 Pixel 140b Pixel 140g Pixel 140r Pixel 715b Anode 715g Anode 715r Anode 730 Partition wall 731 EL layer 732 Cathode 740 Substrate 741b Light-emitting element 741g Light-emitting element 741r Light-emitting element 742 Substrate 743b Coloring layer 743g Coloring layer 743r Coloring layer 744 Overcoat 745b Conductive film 745g Conductive film 745r Conductive film 746g Conductive film 746r Conductive film 750 Insulating film 800 Substrate 801 Conductive film 802 Gate insulating film 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 Substrate 901 Semiconductor film 902 Gate insulating film 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 hole 923 Insulating film 924 EL layer 925 Conductive film 1601 Panel 1602 Circuit board 1603 Connection part 1604 Pixel part 1605 Scanning Line Driving Circuit 1606 Signal Line Driving Circuit 5001 Housing 5002 Housing 5003 Display Unit 5004 Display Unit 5005 Microphone 5006 Speaker 5007 Operation Key 5008 Stylus 5201 Housing 5202 Display Unit 5203 Support Stand 5401 Housing 5402 Display Unit 5403 Keyboard 5404 Pointing Device 5601 Housing 5602 Display Unit 5603 Operation Key 5801 Housing 5802 Display Unit 5803 Audio Input Unit 5804 Audio Output Unit 5805 Operation Key 5806 Light Receiving Unit 6031 Transistor 6033 Light Emitting Element 6034 Anode 6035 EL Layer 6036 Cathode 6037 Insulating Film 6038 Partition Wall 6041 Transistor 6043 Light Emitting Element 6044 Anode 6045 EL Layer 6046 Cathode 6047 Insulating Film 6048 Partition Wall 6051 Transistor 6053 Optical Element 6054 Anode 6055 EL Layer 6056 Cathode 6057 Insulating Film 6058 Partition wall

Claims

1. A pixel includes first to fifth transistors, a light-emitting element, a first wiring, and a second wiring, the first transistor has a function of controlling input of an image signal to the pixel, one of a source and a drain of the second transistor is always electrically connected to one of a source and a drain of the fifth transistor; one of the source and the drain of the third transistor is always electrically connected to the gate of the second transistor; the third transistor has a function of inputting the image signal to a gate of the second transistor through a channel formation region of the third transistor, and a function of holding a potential according to the image signal when the third transistor is in a non-conductive state; one of the source and the drain of the fourth transistor is always electrically connected to the gate of the second transistor; the other of the source and the drain of the fourth transistor is always electrically connected to the first wiring; the other of the source and the drain of the fifth transistor is always electrically connected to a pixel electrode of the light-emitting element; a light-emitting device having a function of controlling a current supplied to the light-emitting element in response to the potential held in a gate of the second transistor when the second wiring is electrically connected to a pixel electrode of the light-emitting element through at least a channel formation region of the second transistor and a channel formation region of the fifth transistor, a first semiconductor film having a channel formation region of the second transistor and a channel formation region of the fifth transistor; a second semiconductor film having a channel formation region of the third transistor and separated from the first semiconductor film; a first conductive film having a region located above the first semiconductor film and functioning as a gate of the second transistor; a second conductive film having a region located above the first semiconductor film and functioning as a gate of the fifth transistor; a third conductive film having a region located above the second semiconductor film and functioning as a gate of the third transistor; a fourth conductive film having a region located above the first semiconductor film and functioning as the other of the source and the drain of the fifth transistor; having the fourth conductive film is always electrically connected to the pixel electrode having a region disposed above the fourth conductive film; The second transistor has a higher ratio of channel length to channel width than the first transistor. Light emitting device.

2. A pixel includes first to fifth transistors, a light-emitting element, a first wiring, and a second wiring, the first transistor has a function of controlling input of an image signal to the pixel, one of a source and a drain of the second transistor is always electrically connected to one of a source and a drain of the fifth transistor; one of the source and the drain of the third transistor is always electrically connected to the gate of the second transistor; the third transistor has a function of inputting the image signal to a gate of the second transistor through a channel formation region of the third transistor, and a function of holding a potential according to the image signal when the third transistor is in a non-conductive state; one of the source and the drain of the fourth transistor is always electrically connected to the gate of the second transistor; the other of the source and the drain of the fourth transistor is always electrically connected to the first wiring; the other of the source and the drain of the fifth transistor is always electrically connected to a pixel electrode of the light-emitting element; a light-emitting device having a function of controlling a current supplied to the light-emitting element in response to the potential held in a gate of the second transistor when the second wiring is electrically connected to a pixel electrode of the light-emitting element through at least a channel formation region of the second transistor and a channel formation region of the fifth transistor, a first semiconductor film having a channel formation region of the second transistor and a channel formation region of the fifth transistor; a second semiconductor film having a channel formation region of the third transistor and separated from the first semiconductor film; a first conductive film having a region located above the first semiconductor film and functioning as a gate of the second transistor; a second conductive film having a region located above the first semiconductor film and functioning as a gate of the fifth transistor; a third conductive film having a region located above the second semiconductor film and functioning as a gate of the third transistor; a fourth conductive film having a region located above the first semiconductor film and functioning as the other of the source and the drain of the fifth transistor; having the fourth conductive film is always electrically connected to the pixel electrode having a region disposed above the fourth conductive film; a first signal input to the gate of the third transistor is different from a second signal input to the gate of the first transistor; The second transistor has a higher ratio of channel length to channel width than the first transistor. Light emitting device.

3. A pixel includes first to fifth transistors, a light-emitting element, a first wiring, and a second wiring, the first transistor has a function of controlling input of an image signal to the pixel, one of a source and a drain of the second transistor is always electrically connected to one of a source and a drain of the fifth transistor; one of the source and the drain of the third transistor is always electrically connected to the gate of the second transistor; the third transistor has a function of inputting the image signal to a gate of the second transistor through a channel formation region of the third transistor, and a function of holding a potential according to the image signal when the third transistor is in a non-conductive state; one of the source and the drain of the fourth transistor is always electrically connected to the gate of the second transistor; the other of the source and the drain of the fourth transistor is always electrically connected to the first wiring; the other of the source and the drain of the fifth transistor is always electrically connected to a pixel electrode of the light-emitting element; a light-emitting device having a function of controlling a current supplied to the light-emitting element in response to the potential held in a gate of the second transistor when the second wiring is electrically connected to a pixel electrode of the light-emitting element through at least a channel formation region of the second transistor and a channel formation region of the fifth transistor, a first semiconductor film having a channel formation region of the second transistor and a channel formation region of the fifth transistor; a second semiconductor film having a channel formation region of the third transistor and separated from the first semiconductor film; a first conductive film having a region located above the first semiconductor film and functioning as a gate of the second transistor; a second conductive film having a region located above the first semiconductor film and functioning as a gate of the fifth transistor; a third conductive film having a region located above the second semiconductor film and functioning as a gate of the third transistor; a fourth conductive film having a region located above the first semiconductor film and functioning as the other of the source and the drain of the fifth transistor; having the fourth conductive film is always electrically connected to the pixel electrode having a region disposed above the fourth conductive film; the first semiconductor film has a bent shape in a channel formation region of the second transistor; Light emitting device.

4. A pixel includes first to fifth transistors, a light-emitting element, a first wiring, and a second wiring, the first transistor has a function of controlling input of an image signal to the pixel, one of a source and a drain of the second transistor is always electrically connected to one of a source and a drain of the fifth transistor; one of the source and the drain of the third transistor is always electrically connected to the gate of the second transistor; the third transistor has a function of inputting the image signal to a gate of the second transistor through a channel formation region of the third transistor, and a function of holding a potential according to the image signal when the third transistor is in a non-conductive state; one of the source and the drain of the fourth transistor is always electrically connected to the gate of the second transistor; the other of the source and the drain of the fourth transistor is always electrically connected to the first wiring; the other of the source and the drain of the fifth transistor is always electrically connected to a pixel electrode of the light-emitting element; a light-emitting device having a function of controlling a current supplied to the light-emitting element in response to the potential held in a gate of the second transistor when the second wiring is electrically connected to a pixel electrode of the light-emitting element through at least a channel formation region of the second transistor and a channel formation region of the fifth transistor, a first semiconductor film having a channel formation region of the second transistor and a channel formation region of the fifth transistor; a second semiconductor film having a channel formation region of the third transistor and separated from the first semiconductor film; a first conductive film having a region located above the first semiconductor film and functioning as a gate of the second transistor; a second conductive film having a region located above the first semiconductor film and functioning as a gate of the fifth transistor; a third conductive film having a region located above the second semiconductor film and functioning as a gate of the third transistor; a fourth conductive film having a region located above the first semiconductor film and functioning as the other of the source and the drain of the fifth transistor; having the fourth conductive film is always electrically connected to the pixel electrode having a region disposed above the fourth conductive film; a first signal input to the gate of the third transistor is different from a second signal input to the gate of the first transistor; the first semiconductor film has a bent shape in a channel formation region of the second transistor; Light emitting device.

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

Images