Display device and electronic apparatus

Abstract

To restrict enlargement of a pixel area although a current to be supplied to an electroluminescence element is reduced.SOLUTION: A switch transistor, a first drive transistor, an electroluminescence element, and a second drive transistor provided between the first drive transistor and the electroluminescence element are provided. Power source potential is applied to a gate of the second drive transistor. Further, drain current of the second drive transistor is controlled according to the first drive transistor and the second drive transistor, in order to control a current value to be supplied to the electroluminescence element.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] TECHNICAL FIELD One embodiment of the present invention relates to a display device and an electronic device. [Background technology]

[0002] In recent years, technological developments have been progressing to increase the resolution of display devices.

[0003] The display device may be, for example, an electroluminescence display device (also called an EL display device). ) and the like (for example, Patent Document 1). A light emitting diode (EL diode) and a driving transistor that controls the amount of current supplied to the EL diode. The device is equipped with a

[0004] In order to increase the definition of the EL display device, the number of pixels is increased to increase the resolution. In this case, in an EL display device, the variation in luminance characteristics among a plurality of pixels is reduced, and It is necessary to increase the operating speed of the driving circuit. As an effect transistor, it has a high field effect mobility and little variation in electrical characteristics. It is preferable to use a transistor, for example, a transistor using a single crystal silicon layer for the channel forming region. It is preferred to use a field effect transistor.

[0005] On the other hand, for a given panel size, increasing the number of pixels increases the area per pixel. The amount of current required for an EL element is determined by its area. Therefore, the pixel area As the size of the display decreases, the area of ​​the EL element also becomes smaller, so it is necessary to reduce the amount of current supplied to the EL element. In order to reduce the amount of current supplied to the EL element, for example, The solution is to reduce the current flowing between the source and drain (also called the drain current). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2006-301629 A Summary of the Invention [Problem to be solved by the invention]

[0007] In conventional display devices, as the resolution increases, the amount of current supplied to the EL element is reduced. This caused problems such as an increase in pixel area, which hindered the development of high-definition display devices. The reason for this is explained below.

[0008] In conventional display devices, the characteristics of other field-effect transistors (field While maintaining the characteristics of the driving transistor (e.g., the effect mobility, threshold voltage, or electrical characteristic variation), To reduce the drain current, the channel length of the drive transistor should be increased and the channel width should be increased. The channel width can only be narrowed to a certain value due to the limits of processing accuracy. Therefore, the drain of the driving transistor is increased by increasing the channel length of the driving transistor. The current must be reduced. If the channel length of the driving transistor becomes longer, the pixel As the area expands, the area per pixel becomes smaller due to higher resolution. It is difficult to increase the channel length of a transistor.

[0009] In view of the above problem, in one embodiment of the present invention, it is possible to reduce the current supplied to the EL element and still obtain a satisfactory pixel surface area. One of the objectives is to suppress the increase in the area. [Means for solving the problem]

[0010] In one aspect of the present invention, a switch transistor, a first driving transistor, and an EL element A second driving transistor is provided between the first driving transistor and the EL element. It constitutes the pixel circuit of a display device.

[0011] The first driving transistor has a gate to which the potential of the data signal is applied via the switch transistor. The drain current value is controlled in response to the potential of the data signal.

[0012] The second driving transistor is formed in the same process as the first driving transistor and has the same conductivity type. A power supply potential is applied to the gate of the second driving transistor. The power supply potential is preferably a constant potential.

[0013] The first driving transistor and the second driving transistor control the value of the current supplied to the EL element. It has the function of controlling

[0014] Further, in one aspect of the present invention, a first driving transistor and a second driving transistor When the first driving transistor is in the linear region, the second driving transistor is in the saturation region. The maximum drain current of the max Then, Id max satisfies the following formula (1). The drain current of the second drive transistor is controlled so as to

[0015]

number

[0016] In the formula (1), L1 is the channel length of the first driving transistor, L2 is the channel length of the second driving transistor, is the channel length of the first drive transistor, W is the channel width of the first drive transistor, μ is the The field effect mobility of the transistor, Vg, is the gate and source of the first drive transistor. Vth is the threshold voltage of the first drive transistor, Cox is the These represent the sum of the gate capacitance of the first drive transistor and the gate capacitance of the second drive transistor, respectively.

[0017] As described above, in one aspect of the present invention, the first driving transistor and the second driving transistor The second driving transistor in the saturation region is controlled by the The value of the drain current is controlled to reduce the value of the current supplied to the EL element.

[0018] In one embodiment of the present invention, a display device including the pixel circuit is provided in a housing of an electronic device. Configure the panel to be displayed. Effect of the Invention

[0019] In one aspect of the present invention, a first driving transistor and a second driving transistor By reducing the drain current of the driving transistor, the current supplied to the EL element is reduced. The sum of the channel length of the first driving transistor and the channel length of the second driving transistor is The channel length can be made shorter than that of the conventional driving transistor, thus increasing the pixel area. can be suppressed. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a circuit diagram illustrating a circuit configuration of a display device. [Diagram 2] FIG. 11 is a circuit diagram illustrating a circuit configuration of a display device of a comparative example. [Diagram 3]FIG. 13 shows the results of calculating the change in drain current when the source and drain voltages of a transistor are changed. [Figure 4] FIG. 13 shows the results of calculating the change in drain current when the source and drain voltages of a transistor are changed. [Diagram 5] 1A and 1B are a schematic plan view and a schematic cross-sectional view illustrating an example of the structure of an active matrix substrate. [Figure 6] FIG. 1 is a schematic cross-sectional view showing a structural example of a display device. [Figure 7] FIG. 1 is a block diagram showing a configuration example of a display device. [Figure 8] 1A to 1C are diagrams for explaining electronic devices. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The following describes an example of an embodiment of the present invention. It should be noted that the present invention is not limited to the above embodiment. It is easy for a person skilled in the art to modify the content of the embodiment without modifying it. The present invention is not limited to the description of the following embodiments.

[0022] The contents of each embodiment can be appropriately combined with each other. The contents can be substituted for each other as appropriate.

[0023] In addition, ordinal numbers such as 1st and 2nd are used to avoid confusion between components. The number of is not limited to the number of ordinal numbers.

[0024] (Embodiment 1) In this embodiment, an example of a display device according to one embodiment of the present invention will be described with reference to FIGS. do.

[0025] First, the circuit configuration of a pixel circuit included in the display device of this embodiment will be described with reference to FIG. FIG. 1 is a circuit diagram showing the circuit configuration of a pixel circuit.

[0026] As shown in FIG. 1, the display device of this embodiment includes a switch transistor, which is a field effect transistor. a first driving transistor 111 which is a field effect transistor; element 130, an EL element (electroluminescence element) 120, and a field effect transistor and a second drive transistor 112 which is a second drive transistor.

[0027] The switch transistor 110 has a source and a drain to which a data signal line DL The potential of the data signal is given by the gate of the switch transistor 110. The potential of the gate signal is given to the switch transistor by the gate signal line GL. By making the transistor 110 a double-gate transistor, the off-state current of the transistor is In addition, in FIG. 1, the switch transistor 110 The transistor is an N-channel type, but is not limited to this and may be a P-channel type transistor. The switch transistor 110 is a transistor for switching a data signal held in the pixel circuit. It has the function of controlling whether or not to rewrite the data.

[0028] The first driving transistor 111 has a source and a drain, and the first power supply line P A first power supply potential VP1 is applied via a first drive transistor 11 The gate of the switch transistor 110 is connected to the other of the source and drain of the switch transistor 110. The gate of the first driving transistor 111 and the switch transistor The other of the source and drain of the capacitor 110 does not necessarily have to be directly connected. The potential of the gate of the driving transistor 111 is controlled by a data signal. In addition, the first driving transistor 111 is not limited to a P-channel transistor. The first driving transistor 111 is not limited to a N-channel transistor. , has the function of controlling the amount of current supplied to the EL element 120 .

[0029] A capacitive potential is applied to one of a pair of electrodes of the capacitor 130 via a capacitor line CsL. The other of the pair of electrodes of the capacitor 130 is connected to the first driving transistor 11. The capacitance element 130 is a MOS capacitance, and is connected to the capacitance line CsL and the gate of the first transistor. A first power supply line PSL1 is connected to the first power supply potential VP1 as a capacitive potential. For example, the capacitance line CSL and the first power supply line PSL1 are not connected to each other, and the capacitance potential is set to the capacitance potential. A potential different from the first power supply potential VP1 may be applied to the capacitor 130. The capacitor element 130 is provided when the data of the data signal is written to the pixel circuit. When the first driving transistor 111 is turned on, a storage capacitor is provided to store the charge stored in the gate of the first driving transistor 111. It has a function as a quantity.

[0030] One of the anode and cathode of the EL element 120 is connected to a second power line PSL2. The second power supply potential VP2 is applied to the EL element 120. The EL element 120 is not limited to a single transistor, and may be an inverse stack EL element. The LED 112 has a function of emitting light with a luminance according to the drain current of the LED 112.

[0031] The second driving transistor 112 is formed in the same process as the first driving transistor 111. The second driving transistor 112 has a solenoid. One of the source and drain of the first driving transistor 111 is a source and drain of the first driving transistor 111. The source and drain of the second driving transistor 112 are connected to the other of the The other of the two is connected to the other of the anode and cathode of the EL element 120. The gate of the second driving transistor 112 is connected to a third power supply line PSL3 via a third power supply line PSL4. A power supply potential VP3 is applied. The third power supply potential VP3 is preferably a constant potential. In addition, if the amplitude is within a certain range, it can be considered as a constant potential. The transistor 112 is not limited to a P-channel transistor, but may be an N-channel transistor. In addition, the channel length of the first driving transistor 111 may be longer than that of the second driving transistor. The channel length of the second driving transistor 112 is not limited to a configuration longer than the channel length of the second driving transistor 112. The channel length of the first driving transistor 111 may be longer than the channel length of the second driving transistor 112. The second driving transistor 112 has a function of controlling the amount of current supplied to the EL element 120. has.

[0032] Next, an example of a method for driving the display device shown in FIG. The first power supply potential is a high power supply potential, and the second power supply potential is a low power supply potential.

[0033] First, the potential of the gate signal line GL is set by the potential of the gate signal, and the switch transistor 110 is turned on. The potential of the data signal line DL is set according to the potential of the data signal. do.

[0034] At this time, the potential of the gate of the first driving transistor 111 is equal to the potential of the data signal. At this time, the drain current of the first driving transistor 111 is Id 111 Let us assume that.

[0035] In addition, the drain current of the second driving transistor 111 is The second driving transistor 112 operates in the saturation region. At this time, the drain current of the second driving transistor 112 is Id 112 Let us assume that.

[0036] The drain current (Id 112 ) is as follows It can be calculated using formula (2).

[0037]

number

[0038] In formula (2), L 112 is the channel length of the second drive transistor 112, W 112 is the second The channel width of the driving transistor 112, μ 112 is the voltage of the second driving transistor 112. Field effect mobility, Vg 112 is the voltage between the gate and source of the second drive transistor 112 , Vth 112 is the threshold voltage of the second drive transistor 112, Cox 112 is the second drive 10 represents the gate capacitance of transistor 112.

[0039] The drain current of the second drive transistor 112 in the saturation region is The drain current of the EL element 120 can be considered to be equal to the drain current of the EL element 111. The degree of the bias voltage is a value that corresponds to the potential of the data signal.

[0040] Even if the EL element 120 deteriorates, the second driving transistor 112 does not become saturated. By operating in this region, fluctuations in the value of the current supplied to the EL element 120 can be suppressed.

[0041] Furthermore, in the display device of this embodiment, when the first driving transistor 111 is in the linear region, The maximum value of the drain current of the second driving transistor 112 in the saturation region is Id 112m ax Then, Id 112max The second driving transformer is set so as to satisfy the following formula (3). The drain current of the first driving transistor 111 and the second driving transistor 112 is This is controlled by controller 112.

[0042]

number

[0043] In formula (3), L 111 is the channel length of the first driving transistor 111, L 112 is the second The channel length of the driving transistor 112, W 111 The transistor of the first driving transistor 111 Channel width, μ 111 is the field effect mobility of the first driving transistor 111, Vg 111 is the The voltage between the gate and source of the driving transistor 111 of 111 The first drive Threshold voltage of transistor 111, Cox Z The first driving transistor 111 and the second driving transistor Each represents the sum of the gate capacitances of the transistors 112.

[0044] The right side of the above formula (3) is the first driving transistor 111 and the second driving transistor 112 shown in FIG. The transistor 112 is regarded as a third driving transistor. One of the source and drain of the transistor is connected to the first power supply line PSL1, and the other is connected to the EL element. The third driving transistor is connected to the other of the anode and cathode of the transistor 120. The channel length of the first driving transistor 111 and the channel length of the second driving transistor 112 shown in FIG. The third drive transistor in the saturation region when the channel length of the third drive transistor is the sum of the channel lengths of the first and second drive transistors 112 and 113. This is equal to the formula for calculating the drain current.

[0045] In the display device of this embodiment, the first driving transistor 111 and the second driving transistor The first driving transistor 112 is formed by the same process and has the same conductivity type. The field effect mobility and threshold voltage of the first driving transistor 111 and the second driving transistor 112 are the same. If the channel length of the first driving transistor 111 and the channel length of the second driving transistor The channel length of the data signal, the amplitude of the data signal, the first power supply potential VP1 to the third power supply potential V By appropriately setting the value of P3, etc., the second driving transistor is set to satisfy the formula (3). For example, the drain current of the first driving transistor 111 can be controlled by the channel length of the second drive transistor 112, the amplitude of the data signal, the first power supply voltage The value of the third power supply potential VP3 is set in accordance with the values ​​of the first power supply potential VP1 and the second power supply potential VP2. Thus, the drain current of the second driving transistor 112 is controlled so as to satisfy the formula (3). It is preferable to control the first driving transistor as long as the formula (3) is satisfied. 111 may be operated in the saturation region.

[0046] In addition, the EL element 120 emits light with a luminance that corresponds to the drain current of the second driving transistor 112. This causes the pixel circuit to emit light (display state). By turning off the transistor 110, the gate of the first drive transistor 111 Since the potential can be maintained at this value, the light emitting state can be maintained.

[0047] Here, when the formula (3) is satisfied, the first driving transistor 111 and the second driving transistor The channel length of the resistor 112 will be described in comparison with a display device of a comparative example.

[0048] First, the circuit configuration of a pixel circuit included in a display device of the comparative example will be described with reference to FIG. 2 is a circuit diagram showing the circuit configuration of a pixel circuit.

[0049] As shown in FIG. 2, the display device of the comparative example has the first driving transistor 111 and In place of the second driving transistor 112, a driving transistor 211 is provided. At this time, the first power supply voltage is applied to one of the source and drain of the driving transistor 211. A potential VP1 is applied to the other of the source and drain of the driving transistor 211. The other of the anode and cathode of the L element 120 is connected to the driving transistor 21. The gate of the switch transistor 110 is connected to the other of the source and drain of the switch transistor 110. Connected.

[0050] Next, in the second driving transistor 112 shown in FIG. The drain current changes when the drain voltage is changed, and the driving transistor shown in Figure 2 In the transistor 211, the change in drain current when the drain voltage is changed is shown in FIG. 3 and 4 are views of the second driving transistor 112 shown in FIG. The drain current changes when the drain voltage is changed, and the driving transistor shown in Fig. 2 In transistor 211, the change in drain current when the drain voltage is changed is calculated. 3 and 4, the horizontal axis represents the drain voltage, and the vertical axis represents the drain The above calculations were performed using Silvaco SMARTSPICE Ver. 3.16.1. 2.This is a calculation using R, and the calculation model is the RPI model with LEVEL=36. In addition, the driving transistor 211, the first driving transistor 111, and the second driving transistor In each of the transistors 112, μ , Vth, and Cox are the same values ​​set based on the parameter conditions of the calculation software. In addition, the driving transistor 211, the first driving transistor 111, and the second driving transistor The channel width of each of the driving transistors 112 is 1 μm. In this case, the drain voltage is in the range of -10V to 2V, and the potential of the data signal is -0.6V or less. The driving transistor 211 and the second driving transistor 212 are different in increments of 0.2 V in the range of 0.2 V to 2 V. The drain current value of 112 is shown.

[0051] FIG. 3A shows a driving transistor 211 having a channel length of 46.9 μm. FIG. 3(B) shows the drain current of the first driving transistor 1. The channel length of the second driving transistor 11 is 30.9 μm, and the channel length of the second driving transistor 112 is Drain current of the second driving transistor 112 at 16 μm, The channel length (L1) of the first driving transistor 111 and the channel length (L2) of the second driving transistor When the sum of the channel lengths (L2) of the second driving transistors 11 and 112 are equal, 2. In other parts, the drain current of the driving transistor 211 The configuration of the first driving transistor 111 is the same as that of the first driving transistor 111. In the calculations described using (A) and (B), the value of the first power supply potential VP1 is set to 2.1 V, and the value of the third power supply potential VP2 is set to 2.1 V. The value of the power supply potential VP3 is 0.6 V. In addition, the value of the second power supply potential VP2 in each calculation is The value is the same. In this case, for example, in the top curve of FIG. 3(B), the drain voltage The saturation region is when is below 0.1V.

[0052] As shown in FIGS. 3A and 3B, the channel length of the driving transistor 211 and the first driving The sum of the channel length of the first driving transistor 111 and the channel length of the second driving transistor 112 is When the drain current Id of the driving transistor 211 is equal to the drain current Id of the driving transistor 211 in the saturation region, 211max The maximum value Id of the drain current of the second driving transistor 112 is 112m ax This is because the first drive transistor 111 operates in the linear region and the second drive transistor The drain current of the first driving transistor 111 is reduced by the driving transistor 112. Therefore, when the drain current of the second driving transistor 112 is reduced, Even in the case where the channel length is increased, the channel length is suppressed from increasing.

[0053] In addition, FIG. 4A shows that the third power supply potential VP FIG. 3 is a diagram showing the drain current of the second driving transistor 112 when only the value of At this time, the value of the third power supply potential VP3 is set to 0.4V.

[0054] As shown in FIG. 4A, even when the third power supply potential is changed, the driving transistor The maximum drain current Id of the 211maxThe second drive transistor 112 The maximum drain current Id 112max is lower.

[0055] In addition, FIG. 4B shows that the first driving transistor The channel length of the second driving transistor 112 is longer than the channel length of the second driving transistor 111. 13 is a diagram showing the drain current of the second driving transistor 112 when only the component is different. In this case, the channel length of the first driving transistor 111 is set to 16 μm, and the channel length of the second driving transistor The channel length of the driving transistor 211 is set to 30.9 μm. The channel length of the first driving transistor 111 and the channel length of the second driving transistor 11 The sum of the two channel lengths is equal.

[0056] As shown in FIG. 4B, the channel length of the second driving transistor 111 is longer than that of the first driving transistor 112. The channel length of the transistor 112 is increased, and the channel length of the driving transistor 211 and the first The channel length of the first driving transistor 111 and the channel length of the second driving transistor 112 Even if the sum of is equal, the maximum drain current of the driving transistor 211 shown in FIG. ValueId 211max The maximum drain current of the second driving transistor 112 shown in FIG. Large Id 112max Therefore, the drain voltage of the second driving transistor 112 is Even when the flow is reduced, the expansion of the channel length is suppressed.

[0057] 3 and 4, the maximum drain current of the second driving transistor 112 in the saturation region is It can be seen that when the maximum value satisfies formula (3), the expansion of the channel length can be suppressed.

[0058] As described with reference to FIGS. 3 and 4, the first driving transistor 111 and the second driving transistor The drain voltage of the second driving transistor 112 in the saturation region is The drain current of the second driving transistor 112 is set so that the maximum value of the current satisfies the formula (3). By controlling The channel lengths of the first driving transistor 111 and the second driving transistor 112 are increased. It can be suppressed.

[0059] Next, a structural example of the display device of this embodiment will be described.

[0060] The display device in this embodiment includes a switch transistor 110, a first drive transistor 111, a capacitance element 130, and a second driving transistor 112 are provided. A first substrate (also called an active matrix substrate), a second substrate, and a first substrate and an electroluminescent element disposed between the first substrate and the second substrate.

[0061] First, a structural example of an active matrix substrate in the display device of this embodiment is shown in FIG. 5(A) and 5(B) show the structure of an active matrix substrate. FIG. 5(B) is a schematic plan view and a schematic cross-sectional view showing a construction example. FIG. 5 is a schematic cross-sectional view taken along line AB. Note that FIG. 5 includes components different from the actual dimensions. For convenience, FIG. 5B shows one example of the active matrix substrate shown in FIG. The double wavy line is an ellipsis symbol.

[0062] The active matrix substrate shown in FIG. 5(A) includes a substrate 510, an insulating layer 511, and a semiconductor layers 513a and 513b, insulating layer 517, conductive layers 518a to 518d, and insulating layer 5 19 and conductive layers 520a through 520d.

[0063] An insulating layer 511 is provided on one surface of the substrate 510 .

[0064] The insulating layer 511 functions as, for example, a base layer.

[0065] Each of the semiconductor layers 513 a and 513 b is provided on a portion of the insulating layer 511 .

[0066] The semiconductor layer 513a includes impurity regions 514a to 514d and an impurity region 515. In addition, the channel of the switch transistor 110 is formed between the impurity region 514a and the impurity region 514b. A panel forming region 516a is provided between the impurity regions 514b and 514c. A channel forming region 516b of the switch transistor 110 is provided. 15 is provided between the impurity region 514c and the impurity region 514d.

[0067] The semiconductor layer 513b includes impurity regions 514e to 514g. A channel forming region of the first driving transistor 111 is formed between the impurity region 514e and the impurity region 514f. A second driving transistor is provided between the impurity region 514f and the impurity region 514g. A channel forming region 516d of the transistor 112 is provided. The channel length of 6c is longer than the channel length of the channel formation region 516d.

[0068] The impurity regions 514a to 514g and the impurity region 515 are impurities that impart a P-type conductivity. The impurity concentration of the impurity region 515 is higher than that of the impurity region 514. The impurity concentration of the capacitance line CSL and the first power supply line PSL1 is higher than that of the capacitance line CSL and the first power supply line PSL2. When a potential different from the first power supply potential VP1 is applied as a capacitive potential without connection, The doping of the layer 513a with an impurity element is omitted, and the impurity region 515 is not provided, and a capacitance element is formed. The semiconductor layer 513a can be used to form the channel of the switch transistor 110. The semiconductor layer functions as one of a pair of electrodes of the capacitor 130. The layer 513b is a channel forming layer of the first driving transistor 111 and a channel forming layer of the second driving transistor 112. It functions as a channel forming layer of the transistor 112 .

[0069] The insulating layer 517 is provided on the semiconductor layers 513a and 513b. the gate insulating layer of the first drive transistor 110, the gate insulating layer of the first drive transistor 111 layer, the gate insulating layer of the second driving transistor 112, and the dielectric layer of the capacitive element 130. It has all the functions.

[0070] Each of the conductive layers 518 a to 518 d is provided on a portion of the insulating layer 517 .

[0071] The conductive layer 518a overlaps with the channel formation regions 516a and 516b with the insulating layer 517 interposed therebetween. The conductive layer 518a functions as a gate of the switch transistor 110. do.

[0072] The conductive layer 518b overlaps with the impurity region 515 with the insulating layer 517 interposed therebetween. The electrode 131 functions as the other of the pair of electrodes of the capacitor 130 .

[0073] The conductive layer 518c overlaps with the channel formation region 516c with the insulating layer 517 interposed therebetween. The gate 518c functions as the gate of the first driving transistor 111.

[0074] The conductive layer 518d overlaps with the channel formation region 516d with the insulating layer 517 interposed therebetween. The gate 518d functions as the gate of the second driving transistor 112.

[0075] The insulating layer 519 is provided over the insulating layer 517 with the conductive layers 518a to 518d interposed therebetween. The insulating layer 519 functions as a planarizing layer.

[0076] Each of the conductive layers 520 a to 520 d is disposed on a portion of the insulating layer 519 .

[0077] The conductive layer 520a is an impurity region at a first opening penetrating the insulating layers 517 and 519. It borders on 514a.

[0078] Conductive layer 520b contacts conductive layer 518b at a second opening through insulating layer 519. The conductive layer 520b is formed at a third opening penetrating the insulating layers 517 and 519. It contacts the impurity region 514e.

[0079] The conductive layer 520c is formed by forming an impurity region at a fourth opening penetrating the insulating layers 517 and 519. The conductive layer 520c is in contact with the fifth opening that penetrates the insulating layer 519. 518c。 518c is in contact with the conductive layer.

[0080] The conductive layer 520d is an impurity region at a sixth opening penetrating the insulating layers 517 and 519. It weighs 514g.

[0081] Further, a structural example of the display device of this embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing a structural example of a display device according to an embodiment. The structure is not limited to one that emits light in a surface direction, but may be one that emits light in a downward direction.

[0082] The display device shown in FIG. 6 includes, in addition to the active matrix substrate shown in FIG. 5, an insulating layer 521 and A conductive layer 522, an insulating layer 523, a light-emitting layer 524, a conductive layer 525, a substrate 530, and a deposition layer 526. It includes a color layer 531 , an insulating layer 532 , and an insulating layer 540 .

[0083] An insulating layer 521 is provided over the insulating layer 519 and the conductive layers 520a to 520d.

[0084] The conductive layer 522 is provided on the insulating layer 521. The conductive layer 522 contacts the conductive layer 520d at a seventh opening that penetrates the EL element 1. In the display device shown in FIG. 22, the insulating layer 521, and the conductive layers 520a to 520d form a capacitance. This makes it possible to suppress fluctuations in the first power supply potential VP1, for example.

[0085] An insulating layer 523 is provided on the conductive layer 522 .

[0086] The light-emitting layer 524 is in contact with the conductive layer 522 at an eighth opening provided in the insulating layer 523. The light-emitting layer 524 functions as the light-emitting layer of the EL element 120 .

[0087] The conductive layer 525 is provided on and in contact with the light-emitting layer 524. It functions as a cathode that 0 has.

[0088] The colored layer 531 is provided on one surface of the substrate 530. The colored layer 531 is The color filter functions as a color filter that transmits light of a specific wavelength.

[0089] The insulating layer 532 is provided on one surface of the substrate 530 with the colored layer 531 interposed therebetween.

[0090] An insulating layer 540 is provided between the insulating layer 532 and the conductive layer 525 .

[0091] Further, each component will be described below.

[0092] The substrate 510 and the substrate 530 may be, for example, a glass substrate, a silicon substrate, or a plastic substrate. A quartz substrate can be used.

[0093] The insulating layer 511 may be, for example, a layer containing an oxide insulating material. Layers containing materials such as silicon, silicon oxynitride, or silicon nitride oxide can be used. In addition, the insulating layer 511 can be formed by laminating layers of materials that can be used for the insulating layer 511. It is also possible.

[0094] As the semiconductor layers 513a and 513b, for example, single crystal semiconductor layers can be used. For example, a single crystal silicon layer can be used.

[0095] Here, an example of forming the semiconductor layers 513a and 513b will be described below.

[0096] For example, a first semiconductor substrate and a second semiconductor substrate having an insulating layer formed on the upper surface thereof are prepared. The first semiconductor substrate is doped with an impurity element that imparts N-type or P-type conductivity. Alternatively, an oxide insulating layer or a nitride insulating layer may be formed in advance on the first semiconductor substrate. stomach.

[0097] For example, an oxide insulating film is formed by a thermal oxidation method, a CVD method, a sputtering method, or the like. This allows the formation of an insulating layer on the second semiconductor substrate.

[0098] Furthermore, an ion beam made of ions accelerated by an electric field is injected into a second semiconductor substrate, An embrittlement region is formed in a region at a certain depth from the surface of the semiconductor substrate. By adjusting the energy, mass and charge of the ions, and the angle of incidence of the ions, the embrittlement region can be reduced. Adjusts the depth of the area.

[0099] For example, ions are implanted into the semiconductor substrate using an ion doping device or an ion implantation device. You can enter.

[0100] The ions to be irradiated may be, for example, one or more of hydrogen and helium. For example, when irradiating hydrogen ions using an ion doping device, the ions to be irradiated On, H3 + By increasing the ratio of Specifically, H + , H2 + , H3 + H3 for the total amount + The proportion of It is preferable that the ratio be 80% or more.

[0101] Furthermore, the first semiconductor substrate and the second semiconductor substrate are connected via an insulating layer provided on the second semiconductor substrate. If an insulating layer is also provided on the first semiconductor substrate, the second semiconductor substrate is bonded to the first semiconductor substrate. The first semiconductor substrate is connected to an insulating layer provided on the first semiconductor substrate through the insulating layer provided on the first semiconductor substrate. The first semiconductor substrate and the second semiconductor substrate are bonded together. The insulating layer provided between the conductive substrates becomes insulating layer 511 .

[0102] Further, a heat treatment is performed to separate the second semiconductor substrate using the embrittlement region as a cleavage plane. In this way, a semiconductor layer can be formed on the insulating layer 511. By irradiating the semiconductor layer with laser light, the flatness of the surface of the semiconductor layer can be improved. Furthermore, by etching a part of the semiconductor layer, the semiconductor layers 513a and 513b are can be formed.

[0103] However, the present invention is not limited to this, and may be applied to semiconductor devices using, for example, a smart cut method or a SIMOX method. Layers 513a and 513b can also be formed. The semiconductor regions formed by providing the regions may be used as the semiconductor layers 513a and 513b. good.

[0104] The impurity regions 514a to 514g and the impurity region 515 are, for example, the semiconductor layers 513a and 513b are doped with an impurity element that gives a conductivity type. For example, an N-channel type In the case of transistors, impurity elements (such as phosphorus) that give N-type conductivity are added, In the case of a P-channel transistor, an impurity element that gives the P-type conductivity (such as boron) etc.) is added.

[0105] The insulating layer 517 may be, for example, silicon oxide, silicon nitride, silicon oxynitride, or silicon nitride oxide. Silicon oxide, aluminum oxide, aluminum nitride, aluminum oxynitride, aluminum nitride oxide Layers containing materials such as aluminum or hafnium oxide can be used. The insulating layer 517 may also be formed by a stack of layers applicable to the layer 517 .

[0106] The conductive layers 518a to 518d may be made of, for example, molybdenum, titanium, chromium, tantalum, Magnesium, silver, tungsten, aluminum, copper, neodymium, or scandium A layer of a material containing a metal material such as a metal oxide can be used. A layer containing a conductive metal oxide may be used as d. Examples of such oxides include indium oxide (In2O3), tin oxide (SnO2), and zinc oxide (Zn O), indium tin oxide (In2O3-SnO2, sometimes abbreviated as ITO) , metal oxides such as indium-zinc oxide (In2O3-ZnO), silicon, and oxides The conductive layers 518a to 518c may be formed of a metal oxide containing silicon oxide or nitrogen. The conductive layers 518a to 518d are formed by stacking layers of a material applicable to 518d. It is also possible.

[0107] The insulating layer 519 may be, for example, silicon oxide, silicon nitride, silicon oxynitride, or silicon nitride oxide. Silicon oxide, aluminum oxide, aluminum nitride, aluminum oxynitride, aluminum nitride oxide Layers containing materials such as aluminum or hafnium oxide can be used. The insulating layer 519 may also be formed by a stack of layers applicable to the layer 519 .

[0108] The conductive layers 520a to 520d may be made of, for example, molybdenum, titanium, chromium, tantalum, Magnesium, silver, tungsten, aluminum, copper, neodymium, ruthenium, or sca A layer of a material containing a metallic material such as indium can be used. A layer containing a conductive metal oxide may also be used as the layer 520d. Examples of oxides include indium oxide (In2O3), tin oxide (SnO2), and zinc oxide. Lead (ZnO), indium tin oxide (In2O3 - SnO2, abbreviated as ITO) metal oxides such as indium zinc oxide (In2O3-ZnO), or silicon The conductive layer 52 may be made of a metal oxide containing silicon, silicon oxide, or nitrogen. The conductive layers 520a to 520d are formed by stacking layers of applicable material. It can also be achieved.

[0109] The insulating layer 521 can be, for example, an organic insulating layer or an inorganic insulating layer.

[0110] The conductive layer 522 may be made of, for example, molybdenum, titanium, chromium, tantalum, magnesium, Silver, tungsten, aluminum, copper, neodymium, ruthenium, scandium, etc. A layer of a material containing a metal material can be used. The conductive layer 522 can also be formed by stacking layers.

[0111] The insulating layer 523 can be, for example, an organic insulating layer or an inorganic insulating layer.

[0112] The light-emitting layer 524 is, for example, a light-emitting layer using a light-emitting material that emits light of a specific color. In addition, a stack of light-emitting layers that emit light of different colors can be used. The light-emitting layer 524 may be formed using the above. The light-emitting material may be a fluorescent material, a phosphorescent material, or the like. The electroluminescent material may be any of a number of electroluminescent materials. For example, a material that emits blue light may be used as the light-emitting material. a first layer of a fluorescent material that emits orange light, a second layer of a phosphorescent material that emits orange light, and A layer of a second phosphorescent material that emits white light is laminated to form an emitting layer that emits white light. The electroluminescent material may be an organic electroluminescent material. Alternatively, inorganic electroluminescent materials can be used. For example, one or more of a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer are provided. The electroluminescent layer may be formed by using the above-mentioned compound.

[0113] The conductive layer 525 can be, for example, a layer of a metal oxide that transmits light. Examples of metal oxides include indium oxide (In2O3), tin oxide (SnO2), and oxide Zinc oxide (ZnO), indium tin oxide (In2O3-SnO2, abbreviated as ITO) metal oxides such as indium-zinc oxide (In2O3-ZnO); Silicon, silicon oxide, and metal oxides containing nitrogen can be used. The conductive layer 525 may also be constructed by a stack of layers of material applicable to 525 .

[0114] The colored layer 531 may be formed by irradiating light having a wavelength of red, light having a wavelength of green, or light having a wavelength of blue. A layer that transmits light having a wavelength of 100 nm and contains a dye or pigment can be used. 531, which transmits light and exhibits the colors cyan, magenta, or yellow, and is a dye or pigment For example, when a dye is contained, the color layer 531 may be formed by, for example, photolithography. A colored layer formed by a graphic method, a printing method, or an inkjet method and containing a pigment. 531 is formed by using a photolithography method, a printing method, an electrodeposition method, an electrophotography method, or the like. For example, by using an inkjet method, the ink can be produced at room temperature, in a low vacuum, or It can be manufactured on a large substrate. It can also be manufactured without using a resist mask. This allows the manufacturing cost and the number of manufacturing steps to be reduced.

[0115] The insulating layer 532 may be, for example, a layer of a material that can be used for the insulating layer 517. Alternatively, the insulating layer 532 may be formed by stacking layers of materials applicable to the insulating layer 532. Note that the insulating layer 532 is not necessarily provided. In this way, it is possible to suppress the intrusion of impurities from the colored layer 531 into the EL element 120 .

[0116] The insulating layer 540 may be, for example, a layer of a resin material. The insulating layer 540 may be constructed by stacking layers of a material suitable for application.

[0117] As shown in FIGS. 5 and 6, in the display device of this embodiment, the EL element 120 is a specific color and an EL element 120 that emits monochromatic light exhibiting the light of This structure includes a colored layer that transmits light having a specific wavelength. A full-color image can be produced without forming a plurality of EL elements 120 that emit light of different colors. This makes the manufacturing process easier and improves yield. For example, the EL element 120 can be manufactured without using a metal mask. The manufacturing process is simplified. Also, the contrast of the image can be improved. The quality of the element 120 can be improved, and the reliability of the EL element 120 can be improved.

[0118] In the display device of this embodiment, the structure of the EL element 120 is a transistor or the like. By adopting a structure in which light is extracted through a substrate on which no element is provided, The area above the region where the light is provided can also be used as a light emitting region, and the aperture ratio can be improved. do.

[0119] Further, a configuration example of the display device of this embodiment will be described with reference to FIG. 1 is a block diagram showing a configuration example of a display device according to an embodiment;

[0120] The display device shown in FIG. 7 has a plurality of pixel circuits arranged in X rows and Y columns (X and Y are natural numbers of 2 or more). A circuit 910, a first data signal line DL_1 to a Y-th data signal line DL_Y, and a first gate The gate signal lines GL_1 to X-th gate signal lines GL_X, the first power supply line PSL1, and the second The first power supply line PSL2 and the third power supply line PSL3.

[0121] For each of the pixel circuits 910, for example, the circuit configuration shown in FIG. For example, three types of pixel circuits for displaying red (R), green (G), and blue (B) can be used. The circuit 910 constitutes one pixel. The horizontal resolution of the display device of this embodiment is 8. 00ppi or more, for example, 800ppi or more and 1000ppi or less. It is preferable that

[0122] At this time, in each of the plurality of pixel circuits 910, the switch transistor 110 is enabled. One of the source and drain of each of the first data signal line DL_1 to the Yth data signal line DL_2 is connected to the corresponding one of the first data signal line DL_3 and the Yth data signal line DL_4. The gate of the switch transistor 110 is connected to one of the first and second inputs DL_Y. The first gate signal line GL_1 through the Xth gate signal line GL_X are connected to any of these gate signal lines.

[0123] In addition, one of the source and drain of the first driving transistor 111 is connected to a first power supply It is connected to line PSL1.

[0124] The other of the pair of electrodes of the capacitor 130 is connected to the first power supply line through a capacitor line CsL. Connected to PSL1.

[0125] In addition, one of the anode and the cathode of the EL element 120 is connected to the second power supply line PSL2. Connected.

[0126] The gate of the second driving transistor 112 is connected to a third power supply line PSL3. can be.

[0127] The potentials of the first data signal line DL_1 to the Y-th data signal line DL_Y are controlled by the driving circuit 901. The driving circuit 901 is controlled by, for example, an analog switch, a latch circuit, and an operation It can be configured using an amplifier.

[0128] The potentials of the first gate signal line GL_1 to the Xth gate signal line GL_X are supplied to the driver circuit 902. The driver circuit 902 is controlled by the pixel circuit 910 in the same process. The driver circuit 902 may be formed on the same substrate as the circuit 910. It can be configured as follows.

[0129] In addition, a first power supply potential VP1 is applied to the first power supply line PSL1, and a second power supply potential VP2 is applied to the second power supply line PSL2. a second power supply potential VP2 provided to the third power supply line PSL3; The potential VP3 can be generated by a power supply circuit 903. The power supply circuit 903 supplies a power supply voltage to the pixel circuit 910 and the driver circuit 902. Alternatively, the first and second electrodes may be formed on separate substrates and connected by wiring or the like.

[0130] Each of the plurality of pixel circuits 910 is electrically connected to a common third power supply line PSL3. This eliminates the need for a separate drive circuit and simplifies the circuit configuration.

[0131] As described with reference to FIG. 7, in the display device of this embodiment, a plurality of pixel circuits 910 are connected in common. By electrically connecting the third power supply line to the third power supply line, a common third power supply potential is supplied. As a result, in each pixel circuit 910, the second driving transistor The value of the current supplied to the EL element 120 can be controlled by 112 .

[0132] (Embodiment 2) In this embodiment, a panel configured using the display device of the first embodiment is provided in a housing. An example of a child device will be described with reference to FIG.

[0133] The electronic device shown in FIG. 8(A) is an example of a portable information terminal.

[0134] The electronic device shown in FIG. 8A includes a housing 1011 and a panel 101 provided in the housing 1011. 2, a button 1013, and a speaker 1014.

[0135] The housing 1011 is provided with a connection terminal for connecting the electronic device shown in FIG. One or more of the buttons for operating the electronic device shown in FIG. 8(A) may be provided.

[0136] The panel 1012 functions as a display panel and a touch panel. As the display device, a panel formed by overlapping a touch panel on the display device shown in the first embodiment is used. It is possible.

[0137] The button 1013 is provided on the housing 1011. For example, the button 1013 is a power button. 3, the electronic device can be turned on or off by pressing the button 1013. Can be controlled.

[0138] The speaker 1014 is provided in the housing 1011. The speaker 1014 outputs sound. It has the function of

[0139] A microphone may be provided on the housing 1011. By providing a microphone, for example, The electronic device shown in A) can be made to function as a telephone.

[0140] The electronic device shown in FIG. 8A is, for example, a telephone, an electronic book, a personal computer, and It has the functions of one or more gaming machines.

[0141] The electronic device shown in FIG. 8B is an example of a foldable information terminal.

[0142] The electronic device shown in FIG. 8B includes a housing 1021a, a housing 1021b, and a A panel 1022a provided on the housing 1021b, a panel 1022b provided on the housing 1021b, and a shaft portion 1023, a button 1024, a connection terminal 1025, a recording medium insertion section 1026, and a speaker and a target 1027.

[0143] The housing 1021 a and the housing 1021 b are connected by a shaft portion 1023 .

[0144] The panel 1022a and the panel 1022b function as a display panel and a touch panel. The panel 1022a and the panel 1022b are the same as those of the display device of the first embodiment. A panel consisting of overlapping chip panels can be applied.

[0145] In the electronic device shown in FIG. 8B, since the shaft portion 1023 is provided, for example, the housing 1021a or the housing The body 1021b is moved to overlap the housing 1021a with the housing 1021b, and the electronic device is folded. It is possible to do so.

[0146] The button 1024 is provided on the housing 1021b. For example, a button 1024 having a function as a power button may be provided. By pressing the button 1024, it is possible to control whether or not power is supplied to the circuitry in the electronic device. can.

[0147] The connection terminal 1025 is provided on the housing 1021a. In addition, a plurality of connection terminals 1025 may be provided in the housing 1021a and the housing 102. The connection terminal 1025 may be provided on one or both of the terminals 1021 and 1022. This is a terminal for connecting other devices.

[0148] The recording medium insertion section 1026 is provided in the housing 1021a. A medium insertion section 1026 may be provided. In addition, multiple recording medium insertion sections 1026 may be provided in the housing 102. For example, the recording medium insertion section may be provided with a card slot. By inserting the card-type recording medium, data can be read from the card-type recording medium to the electronic device. Alternatively, data in the electronic device can be written to the card-type recording medium.

[0149] The speaker 1027 is provided in the housing 1021b. The speaker 1027 outputs sound. The speaker 1027 is provided in the housing 102 instead of the housing 1021b. It may also be provided at 1a.

[0150] A microphone may be provided in the housing 1021a or the housing 1021b. This allows the electronic device shown in FIG. 8B to function as a telephone, for example.

[0151] The electronic device shown in FIG. 8B is, for example, a telephone, an electronic book, a personal computer, and It has the functions of one or more gaming machines.

[0152] The electronic device shown in FIG. 8C is an example of a stationary information terminal. The terminal includes a housing 1031, a panel 1032 provided on the housing 1031, and a button 1033. and a speaker 1034.

[0153] The panel 1032 functions as a display panel and a touch panel. As an example, a panel formed by overlapping the display device of the first embodiment and a touch panel can be applied. .

[0154] The panel 1032 can also be provided on the deck portion 1035 of the housing 1031.

[0155] Further, the housing 1031 includes a ticket output unit for outputting tickets, a coin input unit, and a bill input unit. Or a plurality of them may be provided.

[0156] The button 1033 is provided on the housing 1031. For example, By providing a button 1033 for controlling the operation of the electronic device, pressing the button 1033 can You can control whether or not to supply power.

[0157] The speaker 1034 is provided in the housing 1031. The speaker 1034 outputs sound. It has the function of

[0158] The electronic device shown in FIG. 8(C) is, for example, an automatic teller machine, a device for ordering tickets, etc. It also functions as an information and communication terminal (also called a multimedia station) for gaming machines. Yes.

[0159] FIG. 8D is an example of a stationary information terminal. The electronic device shown in FIG. 8D has a housing 1041. A panel 1042 provided on the housing 1041, and a support stand 104 supporting the housing 1041. 3, a button 1044, a connection terminal 1045, and a speaker 1046.

[0160] The housing 1041 includes a connection terminal for connecting to an external device, and the electronic device shown in FIG. One or more of the buttons may be provided for operating the buttons.

[0161] The panel 1042 has a function as a display panel. The display device of the first embodiment can be applied to the display device of the first embodiment. The touch panel function may be added to the module 1042.

[0162] The button 1044 is provided on the housing 1041. For example, the button 1044 may function as a power button. By providing a button 1044, the circuit in the electronic device can be turned on by pressing the button 1044. You can control whether or not to supply power.

[0163] The connection terminal 1045 is provided on the housing 1041. The connection terminal 1045 is shown in FIG. For example, the connection terminal 1045 in FIG. By connecting the electronic device shown in 8(D) to a personal computer, An image corresponding to a data signal input from a computer can be displayed on the panel 1042. For example, the panel 1042 of the electronic device shown in FIG. If the screen is larger than the monitor, the image displayed on other electronic devices can be enlarged, making it easier for multiple people to view at the same time. become.

[0164] The speaker 1046 is provided in the housing 1041. The speaker 1046 outputs sound. It has the function of

[0165] The electronic device shown in FIG. 8(D) is, for example, an output monitor, a personal computer, or a television. It functions as a telecommunications device.

[0166] As described with reference to FIG. 8, by using the display device of the first embodiment as a panel, The vessel panel can be made high-definition. [Explanation of symbols]

[0167] 110 Switch transistor 111 first drive transistor 112 second drive transistor 120 EL element 130 Capacitive element 211 Drive transistor 510 Substrate 511 Insulating layer 513a Semiconductor layer 513b Semiconductor layer 514a Impurity region 514b Impurity region 514c Impurity region 514d Impurity region 514e Impurity region 514f Impurity region 514g impurity area 515 Impurity region 516a Channel formation region 516b Channel formation region 516c Channel forming region 516d Channel formation region 517 Insulating Layer 518a conductive layer 518b Conductive layer 518c conductive layer 518d conductive layer 519 Insulating Layer 520a Conductive layer 520b conductive layer 520c conductive layer 520d conductive layer 521 Insulating layer 522 Conductive layer 523 Insulating Layer 524 Light-emitting layer 525 Conductive Layer 530 Substrate 531 Colored layer 532 Insulating layer 540 Insulating layer 901 Drive circuit 902 Drive circuit 903 Power supply circuit 910 Pixel circuit 1011 Case 1012 Panel 1013 Button 1014 Speaker 1021a Housing 1021b Case 1022a Panel 1022b Panel 1023 Shaft 1024 Button 1025 Connection terminal 1026 Recording medium insertion section 1027 Speaker 1031 Case Panel 1032 1033 Button 1034 Speaker 1035 Deck section 1041 Case Panel 1042 1043 Support stand 1044 Button 1045 Connection terminal 1046 Speaker

Claims

[Claim 1] a switch transistor having a potential of a data signal applied to one of a source and a drain and a potential of a gate signal applied to a gate; a first drive transistor having a source and a drain to which a first power supply potential is applied and a gate to which the other of the source and drain of the switch transistor is connected; an electroluminescence element having a second power supply potential applied to one of an anode and a cathode; a second drive transistor having the same conductivity type as the first drive transistor, one of a source and a drain connected to the other of the source and drain of the first drive transistor, the other of the source and drain connected to the other of the anode and the cathode of the electroluminescence element, a third power supply potential applied to a gate, and operating in a saturation region in response to a drain current of the first drive transistor; When the first driving transistor is in the linear region, the maximum value of the drain current of the second driving transistor in the saturation region is Id ｍａｘ When the above Id ｍａｘ A display device that satisfies the following formula (1). [0010] (In the formula (1), L １ is the channel length of the first driving transistor, L ２ represents the channel length of the second driving transistor, W represents the channel width of the first driving transistor, μ represents the field effect mobility of the first driving transistor, Vg represents the voltage between the gate and source of the first driving transistor, Vth represents the threshold voltage of the first driving transistor, and Cox represents the sum of the gate capacitances of the first driving transistor and the second driving transistor.

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