Liquid crystal display device

Abstract

To provide a high-definition display device, to provide a display device with low power consumption, to provide a highly reliable display device, or to provide a display device with high visibility. [Solution] A display device including a transistor having a metal oxide, a first conductive layer, a second conductive layer, and a third conductive layer, wherein the channel width of the transistor is 30 μm or more and 1000 μm or less, and the transistor has a semiconductor layer of greater than 2 and less than 50 μm, each of the semiconductor layers having a first region, a second region, and a channel formation region sandwiched between the first region and the second region when viewed from above, the channel formation region having a region overlapping with the first conductive layer, the first region overlapping with the second conductive layer but not overlapping with the first conductive layer, the second region overlapping with a third conductive layer but not overlapping with the first conductive layer, the third conductive layer having a function of transmitting visible light, and the second region and the third conductive layer in a stacked state having a function of transmitting visible light.

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a display device, a display module, and an electronic device. One aspect of the present invention relates particularly to a liquid crystal display device.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. Examples of the semiconductor device include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an electronic device, and a lighting device. ,input devices (e.g., touch sensors, etc.), input / output devices (e.g., touch panels, etc.), Examples include a method for driving them or a method for manufacturing them. [Background technology]

[0003] As display devices, flat panel displays such as liquid crystal display devices and light-emitting display devices are used. Patent document 1 shows an example of a pixel section and a driving circuit of a display device. are.

[0004] In recent years, technology has also been developed that uses transistors made of metal oxides in the pixels of display devices. Patent Document 2 describes a transistor using a metal oxide as a semiconductor material, which is used for a display device. A technique for use as a pixel switching element has been disclosed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-052634 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-227477 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of one embodiment of the present invention is to provide a high-resolution display device. An object of one embodiment of the present invention is to provide a display device with low power consumption. An object of one embodiment of the present invention is to provide a highly reliable display device. An object of one embodiment is to provide a display device with high visibility.

[0007] Another object of one embodiment of the present invention is to provide a liquid crystal display device with a high aperture ratio. Another object of one embodiment of the present invention is to provide a high-resolution liquid crystal display device. .

[0008] The description of these problems does not preclude the existence of other problems. It is not necessary for the specification, drawings, and claims to solve all of these problems. It is possible to extract other problems from the description of the claim. [Means for solving the problem]

[0009] One embodiment of the present invention is a semiconductor device including a transistor, a first conductive layer, a second conductive layer, and a third conductive layer. and the channel width of the transistor is 30 μm or more and 1000 μm or less. The transistor has a plurality of semiconductor layers, and the number of the plurality of semiconductor layers is greater than 2 and less than or equal to 50. Each of the plurality of semiconductor layers has a channel forming region, a first region, and a second region. In each of the plurality of semiconductor layers, the channel forming region is a first region when viewed from above. a first region and a second region, and a channel forming region of each of the plurality of semiconductor layers; The region has a metal oxide, the metal oxide has at least indium or zinc, and a channel formation region of each of the semiconductor layers has a region overlapping with the first conductive layer, The first region overlaps the second conductive layer and does not overlap the first conductive layer, and the second region The third conductive layer overlaps the first conductive layer but does not overlap the third conductive layer, and the third conductive layer transmits visible light. The second region and the third conductive layer in a laminated state transmit visible light. A display device having the function of:

[0010] In the above structure, the width of the channel formation region of each of the plurality of semiconductor layers is , preferably 2 μm or more and 300 μm or less.

[0011] In the above configuration, the first region is a source region and a drain region of the transistor. and the second region serves as the other of the source and drain regions of the transistor. The first region and the second region have a lower electrical resistance than the channel forming region. Preferably, the first region and the second region contain boron or phosphorus.

[0012] In the above configuration, the display device displays by a field sequential driving method. It is preferable that the function be

[0013] In the above configuration, the display device has a liquid crystal element, and the liquid crystal element is a light-scattering liquid crystal element. The liquid crystal element scatters light when in the on state and transmits light when in the off state. It is preferable that [Effects of the Invention]

[0014] According to one embodiment of the present invention, a high-resolution display device can be provided. According to one embodiment of the present invention, a display device with low power consumption can be provided. A display device with higher reliability can be provided. It is possible to provide a display device with high visibility.

[0015] According to one embodiment of the present invention, a liquid crystal display device with a high aperture ratio can be provided. According to one embodiment of the present invention, a high-resolution liquid crystal display device can be provided.

[0016] The description of these effects does not preclude the existence of other effects. It is not necessary for the invention to have all of these effects. Therefore, it is possible to extract other effects. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 is a diagram showing an example of the configuration of a display module. [Figure 2] 1A is a circuit diagram showing an example of the configuration of a pixel, and FIG. 1B is a cross-sectional view showing an example of the configuration of a pixel. [Figure 3] (A) is a top view showing an example of the configuration of a pixel, (B) is a top view showing an example of the configuration of a pixel, (C) is a top view showing an example of the configuration of a part of a pixel, and (D) is a top view showing an example of the configuration of a pixel. [Figure 4] FIG. 1 is a top view illustrating a structural example of a transistor. [Figure 5] (A) is a circuit diagram showing an example of the pixel configuration, (B) is a timing chart explaining the operation, and (C) is a timing chart explaining the operation. [Figure 6] FIG. 2 is a top view showing an example of the configuration of a pixel. [Figure 7] 1A and 1B are cross-sectional views showing an example of the configuration of a pixel; [Figure 8] (A) is a top view of a transistor. (B) is a cross-sectional view of a transistor. (C) is a cross-sectional view of a transistor. [Figure 9] FIG. 1 is a cross-sectional view of a transistor. [Figure 10] (A) is a top view of a transistor. (B) is a cross-sectional view of a transistor. (C) is a cross-sectional view of a transistor. [Figure 11] 1A, 1B, and 1C are diagrams showing examples of electronic devices; [Figure 12] (A) is a diagram showing an example of an electronic device. (B) is a diagram showing an example of an electronic device. (C) is a diagram showing an example of an electronic device. (D) is a diagram showing an example of an electronic device. (E) is a diagram showing an example of an electronic device. [Figure 13] 1A and 1B are diagrams showing an example of a display system; [Figure 14] 1A and 1B are diagrams showing an example of a display system; DETAILED DESCRIPTION OF THE INVENTION

[0018] The embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description. The present invention is not limited to the above embodiments, and various changes and modifications may be made in form and detail without departing from the spirit and scope of the present invention. Therefore, the present invention is based on the following embodiments. The present disclosure should not be construed as being limited to the contents of the preceding paragraph.

[0019] In the configuration of the invention described below, the same parts or parts having similar functions are The same reference numerals are used in common between different drawings, and repeated explanations thereof will be omitted. When referring to a function, the hatch pattern may be the same and no particular symbol may be assigned.

[0020] In addition, the position, size, range, etc. of each component shown in the drawings are not necessarily the same as those in the actual embodiment for ease of understanding. Therefore, the disclosed invention may not necessarily represent the actual position, size, range, etc. The position, size, range, etc. are not necessarily limited to those disclosed in the drawings.

[0021] The words "film" and "layer" may be used interchangeably depending on the situation. For example, the term "conductive layer" can be replaced with "conductive film." Alternatively, for example, the term "insulating film" can be changed to The term can be changed to "insulating layer."

[0022] (Embodiment 1) In this embodiment, a display device of one embodiment of the present invention will be described with reference to FIGS. .

[0023] <Top layout of display module> FIG. 1 shows a top view of the display module.

[0024] The display module shown in FIG. 1 comprises a display device, an integrated circuit (IC) connected to the display device, and and flexible printed circuit boards (FPCa, FPCb).

[0025] The display device includes a display area 100, a gate driver GD_L, and a gate driver GD_R. It has.

[0026] The display area 100 has a plurality of pixels 11 and has the function of displaying an image.

[0027] The pixel 11 can also be called a sub-pixel. For example, a sub-pixel that exhibits red, a sub-pixel that exhibits green, A single pixel unit is composed of a sub-pixel and a sub-pixel that exhibits blue, A full color display can be performed in the region 100. The colors exhibited by the sub-pixels are red, The pixel unit may be, for example, white, yellow, magenta, or cyan, but is not limited to green and blue. In this specification and the like, sub-pixels are not simply referred to as pixels. It may be noted.

[0028] The display device includes a scanning line driver circuit (gate driver), a signal line driver circuit (source driver), The touch sensor may include one or more of a driving circuit for the touch sensor. One or more of these may be externally attached. The LCD panel has a built-in driver and an external integrated circuit IC with a source driver.

[0029] One of the gate drivers GD_L and GD_R controls the pixels in odd-numbered rows. The other has a function to control the pixels in the even-numbered rows. For example, is connected to the scanning line GL_m and controlled by the gate driver GD_L. The pixels on the first row are connected to the scan line GL_m+1 and controlled by the gate driver GD_R. The signal line SL_n in the nth column is connected to a pixel 11 and the pixel 11 electrically connected to the gate driver GD_R are alternately connected. By separating the gate drivers into two opposing sides, The pitch of the connected wiring can be widened. Also, the gate driver can be set only on one side. For this reason, the gate driver By providing the two separate sides, the non-display area on each side of the display device can be narrowed, resulting in a narrower frame.

[0030] The gate driver GD_L and gate driver GD_R are equipped with flexible printed circuits. Signals and power are supplied from the outside via the substrate FPCa. Signals and power are supplied from the outside via the flexible printed circuit board FPCb.

[0031] An example of the circuit configuration of the pixel 11 will be described with reference to FIG. The pixel 11 a shown in FIG.

[0032] One of the source and drain of the transistor 102 is connected to one electrode of the capacitor 105. are electrically connected.

[0033] In addition, it is preferable that a display element is electrically connected to the capacitor element 105 in parallel or in series. Examples of display elements include liquid crystal elements, organic EL elements, LED elements, and MEMS (Metal-Electro-Mechanical Systems). Electro Mechanical Systems (CMOS) elements, etc. .

[0034] Here, one of the source and drain of the transistor 102 and one of the capacitor elements 105 The node to which one electrode is connected is defined as node NA.

[0035] The gate of the transistor 102 is electrically connected to the wiring 121. The other of the two sources or drains is electrically connected to a wiring 124 .

[0036] The wiring 121 can be called a scan line and has a function of controlling the operation of a transistor. The wiring 124 functions as a signal line for supplying an image signal.

[0037] When a transistor with extremely low off-state current is used as the transistor 102, The transistor can hold the potential for a long time. The transistor used in the channel formation region (hereinafter referred to as OS transistor) can be used. .

[0038] Alternatively, the transistor included in the pixel may be a transistor having silicon in a channel formation region. As the Si transistor, an amorphous silicon transistor (hereinafter referred to as a Si transistor) may be used. Transistors with base silicon, crystalline silicon (typically low-temperature polysilicon Examples of such transistors include transistors having silicon dioxide (SiO2) and single crystal silicon (Si).

[0039] For example, when rewriting an image signal every frame, an OS transistor is used. Alternatively, a Si transistor may be used. In this case, it is preferable to use an OS transistor rather than a Si transistor.

[0040] <Top surface layout of pixels> An example of the transistor 102 and the capacitor 105 included in the pixel 11a is shown in FIG. B) and Fig. 3.

[0041] FIG. 3A is an example of a top view of the transistor 102 and the capacitor 105. 2(B) shows a cross section corresponding to the two-dot chain line CD shown in FIG. , and is electrically connected to the transistor 102 via the conductive layer 41 and the like.

[0042] The transistor 102 includes a semiconductor layer 231a, a conductive layer 223a, a conductive layer 221a, and The capacitor element 105 includes a conductive layer 222a and a conductive layer 46b. The conductive layer 41 can be composed of an insulating layer 44 sandwiched between the two conductive layers. The layer 223a and the conductive layer 221a preferably function as a gate electrode. 223a is stacked on the semiconductor layer 231a with an insulating layer 225 interposed therebetween, which functions as a gate insulating film. The conductive layer 221a is disposed on the semiconductor substrate 211 with the insulating layer 211, which functions as a gate insulating film, sandwiched therebetween. The conductive layer 223a and the conductive layer 221a are stacked on the conductive layer 223a. 3a and the conductive layer 221a are electrically connected to each other through an opening 303 provided in the layer sandwiched between the conductive layer 221a. That's fine.

[0043] In FIG. 3A, the conductive layer 223a and the conductive layer 221a are electrically connected by the opening 303. The conductive layer 221a is electrically connected to another region, for example, an adjacent pixel, and serves as a wiring extending to the other region. The conductive layer 223a may be used as a wiring instead of the conductive layer 221a. The layer 221a has an area where it intersects with the conductive layer 222a when viewed from above, for example. By using 1a as the wiring, a plurality of conductive layers are formed between the conductive layer 222a and the conductive layer 221a. The insulating layer can be placed, and the physical distance between the conductive layers can be increased, which prevents short circuits. This has the advantages of making it less likely for this to occur and reducing parasitic capacitance.

[0044] The conductive layer 222a is disposed on the semiconductor layer 231a via an insulating layer. The insulating layer 22a is disposed on the low resistance region of the semiconductor layer 231a. The conductive layer 222a is electrically connected to the semiconductor layer 231a in the opening 301. The conductive layer 222a is preferably provided so as to fill the opening 301. The semiconductor layer 231a is preferably formed in a region 2 that overlaps with the conductive layer 223a. 31ai and two low resistance regions 231an. The two low resistance regions 231an are , as viewed from above, are arranged with the conductive layer 223a sandwiched therebetween. The region 231ai is a channel forming region. It is preferable that one of the two low resistance regions 231an functions as a source region, The other preferably functions as a drain region. silicon, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, arsenic, aluminum, or rare gases In particular, it is preferable that the impurity element contains boron or phosphorus. It may contain two or more of the following.

[0045] The conductive layer 41 is disposed on the conductive layer 46b and on the conductive layer 46c with an insulating layer interposed therebetween. The insulating layer has an opening 304 in the area where it overlaps with the conductive layer 46c. 1 is preferably electrically connected to the conductive layer 46c in the opening 304. The conductive layer 41 is provided to cover the opening 302 .

[0046] In order to make the drawing easier to understand, the conductive layer 41 in FIG. 3(A) is not shown in FIG. 3(B). 3C is a top view of the conductive layer 222a, the conductive layer 46c, and the conductive layer 46b. 4 is a top view in which the conductive layer 46b, the opening 301, the opening 302, etc. are not shown. The conductive layer 46c is disposed on the semiconductor layer 231a via an insulating layer. The insulating layer 231a is disposed on the low resistance region 231an. An opening 302 is provided in the insulating layer. The conductive layer 46c is electrically connected to the semiconductor layer 231a in the opening 302. In addition, the conductive layer 46c is provided so as to cover the inside of the opening 302.

[0047] The conductive layer 222a is electrically connected to one of the source and drain of the transistor 102. The conductive layer 46c is electrically connected to the other of the source and drain of the transistor 102. will be done.

[0048] By using an OS transistor as the transistor 102, the semiconductor layer 231a The semiconductor layer 231a and the like can be configured to have a function of transmitting visible light. By including impurity elements, the semiconductor layer can be made transparent while retaining its function of transmitting visible light. Resistance can be reduced.

[0049] The semiconductor layer 231a, the conductive layer 46c, the conductive layer 46b, and the conductive layer 41 are transparent to visible light. It is preferable to use a material that can transmit visible light. By forming the capacitor 105, the region 111 shown in FIG. 3A transmits visible light. By using the structure of one embodiment of the present invention, the upper surface Therefore, the aperture ratio of the pixel can be increased. By increasing the aperture ratio, it is possible to increase the light extraction efficiency (or pixel transmittance). This makes it possible to reduce the power consumption of the display device. This can improve the display quality of the device.

[0050] The transistor 102 shown in FIG. 3A has a source and a drain electrically connected to each other. One of the wirings can be made up of the conductive layer 222a and the other can be made up of the conductive layer 46c. As shown in the cross section of FIG. 1, each conductive layer is formed on a different layer with an insulating layer interposed between them. Compared to when each conductive layer is formed on the same layer, the distance between the conductive layers is increased when viewed from above. For example, as shown in FIG. 3(D), the conductive layer 222a may be By having a region overlapping with the conductive layer 223a, the wiring width of the conductive layer 222a can be made wider. By increasing the wiring width, for example, the wiring resistance can be reduced. This makes it possible to improve the performance of the display device.

[0051] By increasing the channel width of the transistor 102, the current driving The dynamic capability is improved, and the charging speed of the capacitor 105 is improved. When the channel width is increased, the area occupied by the transistor 102 in the pixel increases, and the opening Here, the channel width refers to, for example, the width of the channel forming region.

[0052] By using the structure of one embodiment of the present invention, when the channel width of the transistor 102 is wide, In this case, a higher aperture ratio may be achieved.

[0053] By using the structure of one embodiment of the present invention, the capacitance can be increased. Even when using liquid crystal materials with high dielectric constants, excellent response speed can be achieved. .

[0054] The semiconductor layer of the transistor may be composed of a plurality of island-shaped semiconductor layers. 4, the semiconductor layer 231a of the transistor 102 is composed of a plurality of island-shaped semiconductor layers. The semiconductor layer 231a shown in FIG. 4 has m (where m is 2 or more and 50 or less, more preferably an integer of 3 or more and 20 or less, and further preferably an integer of 3 or more and 10 or less) The semiconductor layer 231a is composed of a plurality of island-shaped semiconductor layers. This may make it easier for heat to dissipate, thereby suppressing the temperature rise during transistor operation. This may improve the reliability of the transistor.

[0055] The channel width of the transistor 102 is, for example, the width of the semiconductor layer of the transistor 102. In the region overlapping with the gate electrode, from the source region to the drain region as viewed from above This is the width in a direction roughly perpendicular to the direction of travel.

[0056] When the transistor 102 has a plurality of island-shaped semiconductor layers, The channel width is, for example, the sum of the widths of the individual island-shaped semiconductor layers. The width of the semiconductor layer is, for example, 2 μm or more and 300 μm or less, or 3 μm or more and 200 μm or less. Alternatively, it is 5 μm or more and 100 μm or less, or 10 μm or more and 50 μm or less. The width of each island-shaped semiconductor layer is, for example, 100 times the channel length of the transistor 102. It is preferably smaller, more preferably smaller than 50 times, and even more preferably smaller than 25 times.

[0057] When the transistor 102 has the configuration shown in FIG. 4, the channel width is, for example, 30 μm. m or more and 1000 μm or less, or 30 μm or more and 500 μm or less, or 50 μm or more It is less than 350 μm.

[0058] <Example of display device configuration> Using Figs. 5(A), (B), (C), Fig. 6, and Fig. 7(A), (B), two A structural example of a display device including the transistor and two capacitors will be described.

[0059] A display device according to one embodiment of the present invention has a function of adding a correction signal to an image signal.

[0060] The correction signal is added to the image signal by capacitive coupling and supplied to the liquid crystal element. Therefore, the liquid crystal element can display a corrected image. For example, a liquid crystal element can express more gradations than can be expressed using only an image signal. can be done.

[0061] Furthermore, this correction allows the liquid crystal elements to be driven at a voltage higher than the output voltage of the source driver. The voltage supplied to the liquid crystal element within the pixel can be changed to the desired value. This allows existing source drivers to be used, eliminating the cost of designing a new source driver. In addition, it is possible to prevent the output voltage of the source driver from becoming too high. This allows the power consumption of the source driver to be reduced.

[0062] By applying a high voltage to drive the liquid crystal element, the display device can be used over a wide temperature range. This allows for highly reliable display in both low-temperature and high-temperature environments. For example, the display device can be used as a display device for a vehicle or a camera. .

[0063] In addition, since the liquid crystal element can be driven by applying a high voltage, it is possible to produce liquid crystal that exhibits a blue phase. It is also possible to use liquid crystal materials with high driving voltages, such as can.

[0064] In addition, since the liquid crystal element can be driven by applying a high voltage, Overdrive driving, which temporarily increases the voltage to quickly change the orientation of the liquid crystal, The response speed can also be improved.

[0065] The correction signal is generated, for example, by an external device and written to each pixel. This may be performed in real time using an external device, or may be performed using a correction signal stored in a recording medium. The signal may be read out and synchronized with the image signal.

[0066] In the display device according to one embodiment of the present invention, the image signal to be supplied is not changed, but a correction signal is supplied. A new image signal can be generated from the pixels. This reduces the load on external devices compared to generating a new The operation for generating an image signal from pixels can be performed in a small number of steps, and the number of pixels is large. This is also possible for a display device with a very short horizontal period.

[0067] <Circuit> FIG. 5A shows a circuit diagram of pixel 11b.

[0068] The pixel 11b includes a transistor 101, a transistor 102, a capacitor 104, and a 105 and a liquid crystal element 106.

[0069] One of the source and drain of the transistor 101 is connected to one electrode of the capacitor 104. The other electrode of the capacitor 104 is electrically connected to the source or The drain electrode is connected to one of the drains, one of the electrodes of the capacitor element 105, and one of the electrodes of the liquid crystal element 106. electrically connected.

[0070] Here, one of the source and drain of the transistor 101 and one of the capacitors 104 The node to which the electrode of the capacitor element 104 is connected is referred to as a node NS. One of the source and drain of the capacitor 102, one electrode of the capacitor element 105, and the liquid crystal element The node to which one electrode of 106 is connected is defined as node NA.

[0071] The gate of the transistor 101 is electrically connected to the wiring 122. The gate of the transistor 2 is electrically connected to a wiring 121. The other drain is electrically connected to the wiring 125. The other of the drains is electrically connected to the wiring 124 .

[0072] The other electrode of the capacitor element 105 and the other electrode of the liquid crystal element 106 are connected to a common wiring. It is electrically connected to VCOM and the common wiring TCOM. Any potential can be supplied to each of the lines TCOM.

[0073] The wiring 121 and the wiring 122 can be called scan lines, and the operation of the transistors is controlled by the The wiring 125 functions as a signal line for supplying an image signal. The wiring 124 functions as a signal line for writing data to the node NA.

[0074] Each transistor shown in FIG. 5A has a back gate electrically connected to the gate. However, the connection of the back gate is not limited to this. It does not have to be provided.

[0075] By turning off the transistor 101, the potential of the node NS can be maintained. In addition, by turning off the transistor 102, the potential of the node NA can be maintained. In addition, when the transistor 102 is turned off, By supplying a predetermined potential to the node NS, the node The potential of the node NA can be changed in accordance with the change in the potential of the node NS.

[0076] In the pixel 11b, the correction signal written to the node NA from the wiring 124 is 5 is capacitively coupled with the image signal supplied from the liquid crystal element 106. The liquid crystal element 106 can display the corrected image.

[0077] By using a transistor with extremely low off-state current as the transistor 101, The transistor can hold the potential for a long time. Similarly, a transistor with extremely low off-state current can be used as the transistor 102. By using a transistor, the potential of the node NA can be maintained for a long time. An example of a transistor with low resistance is an OS transistor. Alternatively, a Si transistor may be used as the transistor. Both the i-transistor and the d-transistor may be used.

[0078] Alternatively, a Si transistor may be used as the transistor included in the pixel. The transistors include those with amorphous silicon and those with crystalline silicon (representative Examples include transistors using low-temperature polysilicon and single-crystal silicon. .

[0079] For example, when the correction signal and the image signal are rewritten every frame period, the transistor The transistors 101 and 102 may be OS transistors, and Si transistors may be used. When the potential of the node NS or the node NA needs to be maintained for a long time, The transistors 101 and 102 are preferably OS transistors rather than Si transistors. It is preferable to use a resistor.

[0080] <Timing chart> Using the timing chart shown in FIG. 5B, the correction signal (Vp) in the pixel 11b The operation of writing the voltage Vs to the node NA will be explained. It is preferable that the positive signal Vp is written for each frame period. The correction signal (Vp) supplied can be any positive or negative signal. In the following description, a high potential is referred to as "H". , low potential is represented by "L".

[0081] At time T1, the potential of the wiring 121 is set to "H", the potential of the wiring 122 is set to "L", and the potential of the wiring 124 is set to "L". When the potential of the wiring 125 is set to "L", the transistor 102 is turned on, and the potential of the node N The potential of A becomes the potential of the wiring 124. At this time, the potential of the wiring 124 is reset (for example, For example, by setting the voltage to "L", the operation of the liquid crystal element 106 can be reset.

[0082] Before time T1, the display operation of the liquid crystal element 106 in the previous frame period is performed. This is the situation.

[0083] At time T2, the potential of the wiring 121 is set to "L", the potential of the wiring 122 is set to "H", and the potential of the wiring 124 is set to "H". When the potential of the wiring 125 is set to "L", the transistor 101 is turned on. The potential of one electrode of the capacitor 104 becomes "L". This operation is for carrying out the subsequent capacitive coupling operation. This is the reset operation.

[0084] At time T3, the potential of the wiring 121 is set to "H", the potential of the wiring 122 is set to "H", and the potential of the wiring 124 is set to "H". If the potential of the wiring 125 is "L", the potential of the wiring 124 (correction signal (Vp)) is written.

[0085] At time T4, the potential of the wiring 121 is set to "L", the potential of the wiring 122 is set to "H", and the potential of the wiring 124 is set to "H". When the potential of the wiring 125 is set to "L", the transistor 102 is turned off. A correction signal (Vp) is held at node NA.

[0086] At time T5, the potential of the wiring 121 is set to "L", the potential of the wiring 122 is set to "L", and the potential of the wiring 125 is set to "L". When the level is set to "L", the transistor 101 becomes non-conductive, and the write operation of the correction signal (Vp) is stopped. The work ends.

[0087] Next, using the timing chart shown in FIG. 5(C), the image signal ( Vs) and the display operation of the liquid crystal element 106. , it is assumed that a desired potential is supplied at an appropriate timing.

[0088] At time T11, the potential of the wiring 121 is set to "L", the potential of the wiring 122 is set to "H", and the potential of the wiring 124 is set to "H". When the potential is set to "L", the transistor 101 is turned on, and the capacitance of the capacitor 104 causes a The potential of the wiring 125 is added to the potential of the node NA. The potential (Vs) is added to the correction signal (Vp) to create a potential (Vs+Vp)'. +Vp)' also includes fluctuations in potential due to capacitive coupling between wiring capacitances.

[0089] At time T12, the potential of the wiring 121 is set to "L", the potential of the wiring 122 is set to "L", and the potential of the wiring 124 is set to "L". When the potential is set to "L", the transistor 101 becomes non-conductive, and the potential (Vs+V p)' is maintained. Then, the liquid crystal element 106 performs a display operation in accordance with this potential.

[0090] This concludes the explanation of the correction operation of the image signal (Vs) and the display operation of the liquid crystal element 106. The write operation of the correction signal (Vp) and the input operation of the image signal (Vs) are performed continuously. After writing the correction signal (Vp) to all the pixels, the image signal (Vs) The input operation may be performed as follows.

[0091] When the correction operation is not performed, the image signal is supplied to the wiring 124 and the transistor 10 2 may be controlled to be conductive or non-conductive to perform display operation by the liquid crystal element 106. In this case, the transistor 101 may be always off or may be always turned off when a constant potential is supplied to the wiring 125. In this state, the transistor 101 may be always on.

[0092] FIG. 6 shows an example of a top view of pixel 11b.

[0093] The transistors 101 and 102 are OS transistors. As a result, the semiconductor layer 231a and the semiconductor layer 231b have a structure that transmits visible light. It can be concluded that

[0094] In FIG. 6, the conductive layer 222a of the transistor 102 overlaps with the conductive layer 223a. It has an area where

[0095] The transistor 101 shown in FIG. 6 includes a semiconductor layer 231b, a conductive layer 223b, and a conductive layer 223c. The capacitor element 104 includes a conductive layer 46a and a conductive layer 421b. The conductive layer 4 can be composed of a conductive layer 4 and an insulating layer 44 sandwiched between the conductive layers. Reference numeral 1 denotes an electrode common to the capacitor 105 and the capacitor 104 .

[0096] In the pixel of one embodiment of the present invention, the capacitor 104 has a capacitance larger than that of the capacitor 105. For example, the area of ​​the region where the conductive layer 41 and the conductive layer 46a overlap is It is preferable that the area of ​​the conductive layer 41 is larger than the area of ​​the region where the conductive layer 46b overlaps with the conductive layer 46b.

[0097] In addition, the conductive layer 41 and the conductive layer 43c, which will be described later with reference to FIG. 7, etc., are also included. A quantum element is formed.

[0098] The conductive layer 223b and the conductive layer 221b preferably function as gate electrodes. The conductive layer 223b and the conductive layer 221b are formed in an opening in the layer sandwiched between them. The electrodes may be electrically connected to each other.

[0099] The conductive layer 222c is disposed on the semiconductor layer 231b via an insulating layer. The conductive layer 222c is disposed on the low resistance region of the semiconductor layer 231b. It is preferable that the insulating layer 231 is electrically connected to the semiconductor layer 231b through the opening provided in the insulating layer 231.

[0100] The conductive layer 46a is preferably electrically connected to the semiconductor layer 231b. 2c and the conductive layer 46a form either the source or the drain of the transistor 101. and electrically connected to each other.

[0101] The conductive layer 46a and the semiconductor layer 231b preferably have a function of transmitting visible light. stomach.

[0102] Here, the conductive layer 46a, the conductive layer 46b, the conductive layer 46c, and the conductive layer 41 are semiconductor layers. The semiconductor layer 231a and the semiconductor layer 231b transmit visible light more easily. The term "more transparent" means, for example, that the transmittance of visible light is higher. The channel formation region (for example, region 231ai) of the semiconductor layer 31a and the semiconductor layer 231b is The low resistance regions (for example, the low resistance region 231 In some cases, it is more transparent to visible light than

[0103] 7A illustrates an example of a cross section of a display device 10 including a pixel according to one embodiment of the present invention. AB indicates a cross section corresponding to the two-dot chain line AB shown in FIG.

[0104] The display device 10 shown in FIG. 7A includes a substrate 31 and a transistor 1 provided on the substrate 31. 01 and transistor 102, an insulating layer 213 provided on both transistors, and an insulating layer 2 13 and an insulating layer 215 is provided on the insulating layer 214. The display device 10 also includes an FPC 172, a connector 242, and a conductive layer 243 provided on the substrate. In the example shown in FIG. 7(A), the FPC 172 is connected to the connector 242. The conductive layer 43b is electrically connected to the conductive layer 43b. The conductive layer 43b is formed in the same layer as the conductive layer 222a. It is preferable that the above-mentioned method be implemented.

[0105] In addition, the display device 10 shown in FIG. 7A has a substrate 31 disposed opposite to the substrate 31. The substrate 32 has a light-shielding layer 38 on the surface facing the substrate 31, and an overcoat 39 on the surface facing the substrate 31. A coating 135 and a conductive layer 43c are provided in this order.

[0106] The liquid crystal layer 42 is sandwiched between the substrate 31 and the substrate 32. More specifically, for example, the conductive layer 43 c and the conductive layer 41 etc.

[0107] The display device 10 may also include spacers, alignment films, colored layers, and the like.

[0108] The display device 10 shown in FIG. 7A includes a polarizing plate 61, a polarizing plate 63, a backlight unit, and a The backlight unit 30 includes a light emitting element 33, a diffusion plate 34, a light guide plate 35, and a light source 36. 9. If necessary, the light emitting element 33 may be provided with a lens for diffusing light. In (A), the display device 10 has a configuration including a polarizing plate 61 and a polarizing plate 63. The polarizing plate 61 and / or the polarizing plate 63 may be omitted.

[0109] The insulating layer 211 and the insulating layer 225 in contact with the semiconductor layer 231a and the semiconductor layer 231b are made of an oxide. It is preferable that the insulating layer 211 or the insulating layer 225 has a laminated structure. In some cases, it is preferable that at least the layer in contact with the semiconductor layer 231a or the like is an oxide insulating layer. This can prevent oxygen deficiency from occurring in the semiconductor layer 231a and the like, This can improve the reliability of the system.

[0110] Either the insulating layer 213 or the insulating layer 214 is preferably a nitride insulating layer. This can prevent impurities from entering the semiconductor layer 231a and the like, improving the reliability of the transistor. It may be possible to increase sexuality.

[0111] The insulating layer 215 preferably has a planarizing function, and is, for example, an organic insulating layer. The insulating layer 215 may not be formed, and a conductive layer may be formed on and in contact with the insulating layer 214. 46a, etc. may be formed.

[0112] Insulating layer 211, insulating layer 225, insulating layer 213, insulating layer 214, and insulating layer 215 are possible. It is preferable that the film has a function of transmitting visible light.

[0113] It is preferable that the substrate 31 and the substrate 32 have a function of transmitting visible light. There are no significant limitations on the material of the substrate 32, and various substrates can be used. For example, a glass substrate, a quartz substrate, a sapphire substrate, a semiconductor substrate, a ceramic substrate, a metal substrate, Alternatively, a plastic substrate or the like can be used.

[0114] By using a thin substrate, the display device can be made lighter and thinner. Furthermore, by using a substrate thick enough to be flexible, a flexible display device can be realized. can.

[0115] The backlight unit 30 shown in FIG. 7A has a light guide plate 34 disposed directly below the pixels. The light emitting element 33 is provided at the end of the light guide plate 39. The plate 39 has an uneven surface on the side opposite to the diffusion plate 34, and the guided light is scattered by the uneven surface. The light can be emitted in the direction of the diffuser plate 34.

[0116] The light emitting element 33 has a function of emitting visible light.

[0117] The light emitted in the direction of the diffusion plate 34 travels along paths 36 and 37 shown in FIG. The light is then emitted to the substrate 32 side through a path.

[0118] In the path 36, light incident from the substrate 31 side passes through the insulating layer 211, the insulating layer 225, and the insulating layer 21. 3, insulating layer 214, insulating layer 215, conductive layer 46a, insulating layer 44, conductive layer 41, liquid crystal layer 42 , passes through the conductive layer 43c and the overcoat 135 and is injected onto the substrate 32 side.

[0119] In the path 37, the light incident from the substrate 31 side passes through the insulating layer 211 and the low resistance semiconductor layer 231a. region, conductive layer 46c, conductive layer 41, liquid crystal layer 42, conductive layer 43c, and overcoat 135. Then, the light is emitted to the substrate 32 side.

[0120] The light emitting element 33 can be fixed to a printed circuit board 35. For example, the light emitting element 33 may be , RGB light emitting elements are arranged in a row.

[0121] The display device 10 is capable of displaying color images.

[0122] When the display device 10 has a colored layer, light from the light source of the backlight unit 30 is Of the emitted light, light outside a specific wavelength range is absorbed by the colored layer. For example, light emitted from a red pixel (sub-pixel) to the outside of the display module exhibits red color. The light emitted from the green sub-pixel (sub-pixel) to the outside of the display module is green, and the light emitted from the blue sub-pixel (sub-pixel) to the outside of the display module is green. The light emitted from this sub-pixel (sub-pixel) to the outside of the display module exhibits blue color.

[0123] The backlight unit 30 is configured to sequentially blink three color light emitting elements. The display device 10 sequentially blinks the light emitting elements of the three colors, and synchronizes with this. The pixels are driven by the same method, and color display can be performed based on the sequential additive color mixing method. This method can also be called field sequential driving.

[0124] Field sequential driving allows for the display of vivid color images. In addition, smooth moving images can be displayed. There is no need to configure a pixel with multiple sub-pixels of different colors, and the effective reflective area (effective The display area (also called the aperture ratio) can be increased, allowing for brighter displays. In addition, since there is no need to provide a color filter to the pixel, the transmittance of the pixel can also be improved. Furthermore, the manufacturing process can be simplified, and manufacturing costs can be reduced. can be reduced.

[0125] The field sequential driving method is a driving method that displays color by time division. Specifically, light-emitting elements of each color, such as red, green, and blue, are turned on in sequence at different times. The pixels are driven in synchronization with this, and color display is performed based on the sequential additive color mixing method.

[0126] When the field sequential driving method is applied, one pixel is divided into several sub-pixels of different colors. Since it is not necessary to configure the display with pixels, the aperture ratio of the pixels can be increased. It is also possible to increase the resolution of the device. In addition, since there is no need to provide a colored layer such as a color filter, Therefore, there is no light absorption by the colored layer, and the transmittance of the pixel can be improved. The required brightness can be obtained with less power, which allows for low power consumption. This simplifies the manufacturing process of the display device and reduces manufacturing costs.

[0127] When using the field sequential driving method, a high frame frequency is required. In the display device according to one embodiment of the present invention, two capacitors are provided in one pixel, and therefore, the pixel can be stored. It has a large capacity and can supply a high voltage to the liquid crystal element, which improves the response speed of the liquid crystal element. For example, the voltage applied to the liquid crystal element can be temporarily increased to improve the alignment of the liquid crystal. By overdriving the liquid crystal display, the response speed of the liquid crystal element can be improved. Therefore, a high frame frequency is required for the display device of one embodiment of the present invention. This is a suitable configuration when the field sequential driving method is applied.

[0128] A liquid crystal material having a small rotational viscosity coefficient is preferable because it can speed up the response of the liquid crystal element. In general, the rotational viscosity coefficient of the liquid crystal material is between 10 mPa·sec and 150 mPa·sec. It is preferable that:

[0129] In FIG. 7A, the backlight unit 30 uses a light guide plate 39 to guide light from the substrate 31 side. The backlight unit 30 is configured to allow light to enter directly from the pixel facing the substrate 31. For example, a planar light emitting element may be provided facing the substrate 31. The configuration may be such that the two are provided to match each other.

[0130] FIG. 7B shows a transistor 101 electrically connected to one of the source and the drain. In this example, the electrode is formed using a conductive layer 46d formed in the same layer as the conductive layer 46c. The conductive layer 46d has a function of transmitting visible light. The semiconductor layer 231b overlapping the conductive layer 231b also has a function of transmitting visible light. In the area where the backlight unit 46a overlaps the conductive layer 46d but does not overlap the conductive layer 223b, The light emitted from the nozzle 30 can be emitted toward the substrate 32 side.

[0131] <Materials of components> Next, the components of the display device and display module of this embodiment can be used. Details of materials etc. will be explained.

[0132] There are no significant limitations on the material of the substrate of the display device, and various substrates can be used. For example, glass substrates, quartz substrates, sapphire substrates, semiconductor substrates, ceramic substrates, gold substrates, A metal substrate, a plastic substrate, or the like can be used.

[0133] By using a thin substrate, the display device can be made lighter and thinner. Furthermore, by using a substrate thick enough to be flexible, a flexible display device can be realized. can.

[0134] There are two types of liquid crystal materials: positive type, in which the anisotropy of the dielectric constant (Δε) is positive, and negative type, in which the anisotropy of the dielectric constant (Δε) is negative. In one embodiment of the present invention, either type of material can be used. The optimum liquid crystal material can be used depending on the mode and design.

[0135] In the display device, liquid crystal elements with various modes can be used. For example, T N mode, FFS mode, IPS mode, ASM (Axially Symmetric aligned micro-cell mode, OCB (Optically Coated Enhanced Birefringence mode, FLC (Ferroele ctric Liquid Crystal) mode, AFLC (AntiFerroe lectric Liquid Crystal) mode, ECB (Electrica Low Power Controlled Birefringence mode, VA-IPS mode A liquid crystal element in which a guest-host mode or a guest-host mode is applied can be used.

[0136] The liquid crystal element is an element that controls the transmission or non-transmission of light by the optical modulation action of the liquid crystal. The optical modulation effect of the liquid crystal is due to the electric field (horizontal electric field, vertical electric field or The liquid crystal used in the liquid crystal element is thermoelectric. Tropical liquid crystal, low molecular liquid crystal, polymer liquid crystal, polymer dispersed liquid crystal (PDLC) r Dispersed Liquid Crystal), ferroelectric liquid crystal, antiferroelectric These liquid crystal materials can exhibit a cholesteric phase, a smectic phase, or a smectic phase depending on the conditions. It shows mectic phase, cubic phase, chiral nematic phase, isotropic phase, etc.

[0137] As described above, the display device of the present embodiment is configured to drive the liquid crystal element by applying a high voltage. Therefore, a liquid crystal that exhibits a blue phase may be used. When the temperature of a cholesteric liquid crystal is increased, a transition from the cholesteric phase to the isotropic phase occurs. The blue phase is only manifested in a narrow temperature range, so in order to improve the temperature range, The liquid crystal layer uses a liquid crystal composition in which 5% by weight or more of a chiral agent is mixed. A liquid crystal composition containing a liquid crystal and a chiral agent has a short response time and exhibits optical isotropy. The liquid crystal composition containing the liquid crystal exhibiting the blue phase and the chiral agent does not require alignment treatment and has a wide viewing angle. In addition, since there is no need to provide an alignment film, rubbing treatment is not required. It is possible to prevent electrostatic damage caused by the electrostatic discharge treatment, and the display panel during the manufacturing process This can reduce the risk of malfunction or damage.

[0138] The liquid crystal element may be a light-scattering type liquid crystal element. It is preferable to use an element having a composite material of liquid crystal and polymer. For example, a polymer dispersion type liquid crystal Crystal (PDLC(Polymer Dispersed Liquid Crystal) Alternatively, a polymer network liquid crystal (PNLC) element can be used. A mer Network Liquid Crystal (LCC) element may also be used.

[0139] The light-scattering liquid crystal element has a three-dimensional network structure of liquid crystal in a resin part sandwiched between a pair of electrodes. The liquid crystal portion is made of a material such as nematic liquid crystal. The resin portion can be made of a photo-curable resin. Examples of the polymers include monofunctional monomers such as acrylate and methacrylate, diacrylate, Polyfunctional monomers such as acrylate, triacrylate, dimethacrylate, and trimethacrylate Alternatively, a polymerizable compound in which these are mixed can be used.

[0140] Light-scattering liquid crystal elements utilize the anisotropy of the refractive index of the liquid crystal material to transmit or scatter light. The resin portion may also have anisotropy in refractive index. When the liquid crystal molecules are aligned in a certain direction according to the voltage applied to the element, The difference in refractive index between the liquid crystal part and the resin part becomes smaller, and the light incident along this direction is scattered by the liquid crystal part. Therefore, the light scattering type liquid crystal element appears transparent from this direction. On the other hand, when the alignment of liquid crystal molecules becomes random according to the applied voltage, Since there is no significant change in the difference in refractive index between the liquid crystal part and the resin part, the incident light is scattered by the liquid crystal part. Therefore, the light-scattering liquid crystal element remains opaque regardless of the viewing direction.

[0141] When a light-scattering liquid crystal element is used, the alignment film and the polarizing plate are not required.

[0142] When a light-scattering type liquid crystal element is used as the liquid crystal element, for example, the light-scattering type liquid crystal element is in the OFF state. For example, a state in which no voltage is applied or a state in which the absolute value of the applied voltage is small. When the absolute value of the applied voltage is increased, the light is transmitted and the device is in the ON state. The display device is operated in a mode in which light is scattered when the light is scattered. In this case, the display device can be transparent in the transparent state (non-display state). When the scattering action is performed, a color display can be made. It is sometimes called a mode.

[0143] Examples of conductive materials that transmit visible light include indium (In), zinc (Zn), It is advisable to use a material containing one or more selected from tin (Sn). Indium, indium tin oxide (ITO), indium zinc oxide, tungsten oxide Indium oxide containing tungsten oxide, indium zinc oxide containing titanium oxide Indium oxide, indium tin oxide with titanium oxide, indium tin oxide with silicon oxide Examples include zinc tin oxide (ITSO), zinc oxide, and zinc oxide containing gallium. A film containing graphene can also be used. The film containing graphene is, for example, graphene oxide. It can be formed by reducing a film containing fluorine.

[0144] In addition, a conductive film that transmits visible light can be formed using an oxide semiconductor (hereinafter A conductive film formed using an oxide semiconductor is also called an oxide conductive layer. For example, it is preferable to contain indium, and In-M-Zn oxide (wherein M is Al, Ti, or G) is used. It is more preferred that the metal oxide contains at least one of the elements selected from the group consisting of Cr, Y, Zr, La, Ce, Nd, Sn and Hf.

[0145] The oxide semiconductor has at least one of oxygen vacancies and impurity concentrations such as hydrogen and water in the film. On the other hand, oxide semiconductors are semiconductor materials whose resistance can be controlled by A treatment that increases at least one of oxygen deficiency and impurity concentration in the body layer, or By selecting a treatment that reduces at least one of the impurity concentrations, the oxide conductive layer The resistivity can be controlled.

[0146] In this way, the oxide conductive layer formed using an oxide semiconductor has a carrier density A high-resistance and low-resistance oxide semiconductor layer, a conductive oxide semiconductor layer, or a highly conductive oxide semiconductor layer It can also be called a compound semiconductor layer.

[0147] The transistor included in the display device of this embodiment is a top-gate or bottom-gate transistor. Alternatively, gate electrodes may be provided above and below the channel. The semiconductor material used for the transistor is not particularly limited, and examples thereof include oxide semiconductors, silicon Examples include silicon and germanium.

[0148] The crystallinity of the semiconductor material used in the transistor is not particularly limited. Semiconductors with crystallinity (microcrystalline semiconductors, polycrystalline semiconductors, single-crystal semiconductors, or partially crystalline semiconductors) When a semiconductor having crystallinity is used, the transistor This is preferable because it can suppress the deterioration of the transistor characteristics.

[0149] For example, a Group 14 element, a compound semiconductor, or an oxide semiconductor may be used for the semiconductor layer. Typically, a semiconductor containing silicon, a semiconductor containing gallium arsenide, or an indium An oxide semiconductor containing fluorine can be used as the semiconductor layer.

[0150] An oxide semiconductor is preferably used as a semiconductor in which a channel of a transistor is formed. In particular, it is preferable to use an oxide semiconductor having a larger band gap than silicon. Use a semiconductor material with a wider band gap and lower carrier density than silicon. This is preferable because it is possible to reduce the current in the off state of the transistor.

[0151] By using an oxide semiconductor, fluctuations in electrical characteristics are suppressed, resulting in highly reliable transistors. This can be achieved.

[0152] In addition, due to its low off-state current, the charge stored in the capacitance can be released for a long period of time via the transistor. By applying such a transistor to a pixel, It is also possible to stop the driving circuit while maintaining the gradation of the displayed image. This makes it possible to realize a display device with reduced power consumption.

[0153] The transistor has a highly purified oxide semiconductor layer in which formation of oxygen vacancies is suppressed. This makes it possible to reduce the current value in the off state of the transistor (off-state current value). Therefore, the retention time of the electric signals such as the image signals can be extended. When the power is on, the write interval can be set longer, so the frequency of refresh operations can be reduced. This reduces the power consumption.

[0154] Furthermore, a transistor using an oxide semiconductor can have relatively high field-effect mobility. Therefore, high-speed driving is possible. When such a transistor capable of high-speed driving is used in a display device, By doing so, the transistors of the display section and the transistors of the driver circuit section are formed on the same substrate. That is, a semiconductor formed by a silicon wafer or the like can be used as a driving circuit. Since there is no need to use a conductor device, the number of components in the display device can be reduced. The display also uses transistors capable of high-speed operation, providing high-quality images. It is possible.

[0155] The transistors of the gate drivers GD_L and GD_R and the transistors of the display area 100 The transistors may be of the same structure or of different structures. The transistors may all have the same structure, or two or more types of structures may be combined. Similarly, the transistors in the display area 100 may all have the same structure. Alternatively, two or more types of structures may be used in combination.

[0156] Insulating materials that can be used for the insulating layers, overcoats, etc. of a display device include: Organic insulating materials or inorganic insulating materials can be used. For example, acrylic resin, epoxy resin, polyimide resin, polyamide resin, polyimide amide resin, siloxane resin, benzocyclobutene resin, phenol resin, etc. The inorganic insulating layer may be a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a nitride film, or a silicon nitride film. silicon oxide film, aluminum oxide film, hafnium oxide film, yttrium oxide film, silicon oxide gallium oxide film, tantalum oxide film, magnesium oxide film, lanthanum oxide film, Examples include a cerium oxide film and a neodymium oxide film.

[0157] In addition to the gate, source, and drain of the transistor, various wirings and electrodes of the display device Conductive layers such as aluminum, titanium, chromium, nickel, copper, yttrium, and zirconia are also suitable. Metals such as aluminum, molybdenum, silver, tantalum, and tungsten, as well as materials containing these metals as the main component. It is made up of a single layer or a laminated structure using one or more of the alloys that are the components. For example, a two-layer structure in which a titanium film is laminated on an aluminum film, or a tungsten film Two-layer structure with titanium film laminated on top, two-layer structure with copper film laminated on top of molybdenum film, molybdenum Two-layer structure with copper film laminated on alloy film containing tungsten and copper-magnesium-aluminum A two-layer structure in which a copper film is laminated on an aluminum alloy film, a titanium film or titanium nitride film, and the titanium film Alternatively, an aluminum film or copper film is laminated on the titanium nitride film, and then a titanium film is further laminated on top of that. a three-layer structure forming a titanium nitride film or a molybdenum nitride film, a molybdenum film or a molybdenum nitride film, An aluminum film or a copper film is laminated on the molybdenum film or the molybdenum nitride film. There are three-layer structures, such as a molybdenum film or molybdenum nitride film formed on top of the first layer. For example, when the conductive layer has a three-layer structure, the first and third layers are made of titanium, titanium nitride, molybdenum, and the like. Molybdenum, tungsten, alloys containing molybdenum and tungsten, molybdenum and zirconium The first layer is made of an alloy containing molybdenum or molybdenum nitride, and the second layer is made of copper, aluminum, or It is preferable to form a film made of a low resistance material such as gold, silver, or an alloy of copper and manganese. In addition, ITO, indium oxide containing tungsten oxide, and Indium zinc oxide containing titanium oxide, indium oxide containing titanium oxide Conductive materials with light-transmitting properties such as indium tin oxide, indium zinc oxide, and ITSO are used. Note that an oxide conductive layer may be formed by controlling the resistivity of an oxide semiconductor. .

[0158] A silicon nitride film is suitable for the insulating layer 44 that functions as a dielectric of the capacitance element.

[0159] The adhesive layer 141 may be made of a thermosetting resin, a photocurable resin, or a two-liquid mixed curable resin. For example, acrylic resin, urethane resin, epoxy resin, etc. For example, a grease or a siloxane resin can be used.

[0160] The connector 242 may be, for example, an anisotropic conductive film (ACF). c Conductive Film), or Anisotropic Conductive Paste (ACP) A nebulizer such as a nebulizer or a thermotropic conductive paste can be used.

[0161] The colored layer is a colored layer that transmits light in a specific wavelength range. Materials that can be used for the colored layer Examples of the material include metal materials, resin materials, and resin materials containing pigments or dyes. do.

[0162] The light-shielding layer 38 is provided, for example, between adjacent colored layers of different colors. A black matrix formed using a resin material containing a pigment or dye. It can be used as the light-shielding layer 38. The light-shielding layer 38 can be used for other parts than the display part, such as a drive circuit part. It is preferable to provide the light emitting element also in the outer region, since this can suppress leakage of light such as guided light.

[0163] The backlight unit 30 may be a direct type backlight or an edge light type backlight. The light source can be a light emitting diode (LED). de), organic EL (Electroluminescence) elements, etc. can be used. Cut.

[0164] The thin films (insulating films, semiconductor films, conductive films, etc.) that make up the display device are each formed by sputtering. Chemical Vapor Deposition (CVD) method, vacuum evaporation method, pulsed laser deposition (PLD) ition) method, Atomic Layer Deposition (ALD) method The CVD method can be, for example, a plasma-enhanced chemical vapor deposition (CVD) method. PECVD:Plasma Enhanced Chemical Vapor Dep Examples of thermal CVD methods include organometallic CVD. Chemical vapor deposition (MOCVD: Metal Organic CVD) is one example.

[0165] The thin films (insulating film, semiconductor film, conductive film, etc.) that make up the display device are each formed by spin coating. , dip, spray application, inkjet printing, dispensing, screen printing, off Methods such as set printing, slit coating, roll coating, curtain coating, knife coating, etc. It can be formed by a tool such as a doctor knife.

[0166] The thin films constituting the display device can be processed using photolithography or the like. Alternatively, island-shaped thin films may be formed by a film formation method using a shielding mask. The thin film is processed by imprinting, sandblasting, or lift-off. In the photolithography method, a resist mask is formed on the thin film to be processed. a method of processing the thin film by etching or the like and removing the resist mask; After forming a thin film, the thin film is exposed to light and developed to be processed into a desired shape. , there is.

[0167] In the photolithography method, the light used for exposure is, for example, i-line (wavelength 365nm) m), g-line (wavelength 436 nm), h-line (wavelength 405 nm), and a mixture of these In addition, ultraviolet light, KrF laser light, ArF laser light, etc. can be used. The exposure may also be performed by immersion exposure technology. Extreme ultraviolet (EUV) and X-rays. In addition, electron beams can be used instead of light for exposure. The use of a wire or an electron beam is preferable because it allows extremely fine processing. When exposure is performed by scanning a beam such as a electron beam, a photomask is not required. be.

[0168] There are several methods for etching thin films: dry etching, wet etching, and sandblasting. Methods such as these can be used.

[0169] This embodiment mode can be combined with other embodiment modes as appropriate.

[0170] (Embodiment 2) This embodiment will describe an example of a transistor that can be used in one embodiment of the present invention. .

[0171] [Configuration example 1] 8A is a top view of a transistor 200, and FIG. 8B is a top view of the transistor 200 shown in FIG. 8(C) corresponds to a cross-sectional view taken along the dashed line A1-A2 shown in FIG. 8(A). It corresponds to a cross-sectional view taken along the dashed line B1-B2. Some of the components of the transistor 200 (such as the gate insulating layer) are omitted in the illustration. The dashed line A1-A2 direction is the channel length direction, and the dashed line B1-B2 direction is the channel width direction. In addition, the top view of the transistor will be the same as that of FIG. Similarly, some of the components are omitted in the illustration.

[0172] The transistor 200 is provided over a substrate 109, and includes an insulating layer 103, a semiconductor layer 108, an insulating film 109 ... The insulating layer 116 includes an insulating layer 118, an insulating layer 118, an insulating layer 110, a metal oxide layer 114, a conductive layer 112, and an insulating layer 116. The island-shaped semiconductor layer 108 is provided on the insulating layer 103. The insulating layer 110 is The metal oxide layer 114 and the semiconductor layer 108 are provided in contact with each other. The conductive layer 112 is stacked in this order on the insulating layer 110 and overlaps with the semiconductor layer 108. The insulating layer 116 has a portion where the insulating layer 110 is formed, a side surface of the metal oxide layer 114, The insulating layer 118 is provided to cover the upper and side surfaces of the insulating layer 111 and the conductive layer 112. It is installed over 6.

[0173] A portion of the conductive layer 112 functions as a gate electrode. A portion of the insulating layer 110 functions as a gate insulator. The transistor 200 has a gate electrode provided on the semiconductor layer 108. This is a so-called top-gate transistor.

[0174] 8A and 8B, the transistor 200 has a structure in which the insulating layer 118 The conductive layer 120a and the conductive layer 120b may be formed on the substrate 110. The conductive layer 120a and the conductive layer 120b function as a source electrode and a drain electrode. b are the openings 14 provided in the insulating layer 118, the insulating layer 116, and the insulating layer 110, respectively. 1a and the opening 141b, it is electrically connected to a region 108n, which will be described later.

[0175] The semiconductor layer 108 preferably comprises a metal oxide.

[0176] For example, the semiconductor layer 108 may be made of indium and M (M is gallium, aluminum, silicon, etc.). Ni, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel , germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium one or more selected from the group consisting of aluminum, tantalum, tungsten, and magnesium; and zinc. In particular, M is aluminum, gallium, yttrium, or It is preferable to use one or more selected from tin.

[0177] In particular, the semiconductor layer 108 is made of an oxide containing indium, gallium, and zinc. It is preferable.

[0178] The semiconductor layer 108 may be a layer having a different composition, a layer having a different crystallinity, or a layer having a different impurity concentration. Alternatively, a laminated structure may be used in which different layers are laminated.

[0179] The conductive layer 112 and the metal oxide layer 114 are processed so that their top surface shapes roughly match each other. It has been done.

[0180] In this specification, the phrase "the upper surface shapes are roughly the same" means that there is at least a small difference between the layers. For example, the upper and lower layers may have the same mask pattern. This includes cases where the entire surface is processed using the same mask pattern, or where part of the surface is processed using the same mask pattern. The contours do not overlap, and the contour of the upper layer is located inside the contour of the lower layer, or the contour of the upper layer is located inside the contour of the lower layer. In this case, the top surface shape is also said to roughly match.

[0181] The metal oxide layer 114 located between the insulating layer 110 and the conductive layer 112 is It functions as a barrier film that prevents oxygen contained therein from diffusing toward the conductive layer 112. The metal oxide layer 114 is formed by diffusing hydrogen and water contained in the conductive layer 112 to the insulating layer 110 side. The metal oxide layer 114 also functions as a barrier film to prevent, for example, at least the insulating layer 11 A material that is less permeable to oxygen and hydrogen than 0 can be used.

[0182] The metal oxide layer 114 allows the conductive layer 112 to easily absorb oxygen, such as aluminum or copper. Even if a thin metal material is used, oxygen does not diffuse from the insulating layer 110 to the conductive layer 112. Even when the conductive layer 112 contains hydrogen, the conductive layer 112 Therefore, it is possible to prevent hydrogen from diffusing into the semiconductor layer 108 via the insulating layer 110. As a result, the carrier density in the channel formation region of the semiconductor layer 108 is made extremely low. It is possible.

[0183] The metal oxide layer 114 can be made of an insulating material or a conductive material. If the metal oxide layer 114 has insulating properties, it functions as a part of the gate insulating layer. If the metal oxide layer 114 is conductive, it functions as a part of the gate electrode.

[0184] The metal oxide layer 114 is made of an insulating material having a higher dielectric constant than silicon oxide. In particular, an aluminum oxide film, a hafnium oxide film, or a hafnium aluminate film is preferable. It is preferable to use a film such as a PET film, since the driving voltage can be reduced.

[0185] The metal oxide layer 114 may be, for example, indium oxide or indium tin oxide (ITO). or silicon-containing indium tin oxide (ITSO), In particular, conductive oxides containing indium are preferred because of their high conductivity. .

[0186] The metal oxide layer 114 may be an oxide material containing one or more of the same elements as the semiconductor layer 108. In particular, it is preferable to use an oxide semiconductor material that can be used for the semiconductor layer 108. In this case, it is preferable to use the same type of metal oxide layer 114 as the semiconductor layer 108. By applying metal oxide films formed using sputtering targets, equipment can be standardized. This is preferable because it allows

[0187] Alternatively, both the semiconductor layer 108 and the metal oxide layer 114 may contain indium and gallium. When a metal oxide material containing gallium is used, the metal oxide layer 114 has a higher gallium content than the material of the semiconductor layer 108. When a material with a high composition ratio (content ratio) of ammonium is used, the metal oxide layer 114 has a high resistance to oxygen. This is preferable because it can further enhance the blocking property. By using a material with a higher indium composition ratio than the material of the metal oxide layer 114, The field effect mobility of the transistor 200 can be increased.

[0188] The metal oxide layer 114 is preferably formed using a sputtering apparatus. For example, when an oxide film is formed using a sputtering device, it is formed in an atmosphere containing oxygen gas. This allows oxygen to be suitably added to the insulating layer 110 and the semiconductor layer 108.

[0189] The semiconductor layer 108 has a region overlapping with the conductive layer 112 and a pair of low-resistance regions sandwiching the region. The region of the semiconductor layer 108 that overlaps with the conductive layer 112 is a transistor On the other hand, the region 108n functions as a channel forming region of the transistor 200. The source or drain region of the semiconductor substrate is formed by the gate electrode.

[0190] The region 108n is a region with a lower resistance and a higher carrier concentration than the channel formation region. These regions are also called regions with high oxygen vacancy density, regions with high impurity concentration, or regions that are n-type. can be done.

[0191] The region 108n of the semiconductor layer 108 is a region containing an impurity element. Examples of suitable elements include hydrogen, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, arsenic, aluminum, and Typical examples of rare gases include helium, neon, and aluminum. In particular, it is preferable that the material contains boron or phosphorus. In addition, two or more of these elements may be contained.

[0192] The insulating layer 110 is formed in a region in contact with the channel forming region of the semiconductor layer 108, i.e., the conductive layer 1 The insulating layer 110 has a region overlapping with the low resistance region 12 of the semiconductor layer 108. 08n and has a region that does not overlap with the conductive layer 112.

[0193] The insulating layer 103 and the insulating layer 110 in contact with the channel formation region of the semiconductor layer 108 are It is preferable to use an oxide film. For example, a silicon oxide film, a silicon oxynitride film, an oxide An oxide film such as an aluminum film can be used. The oxygen released from the insulating layer 103 and the insulating layer 110 during the heat treatment in the manufacturing process is transferred to the semiconductor. The oxygen vacancies in the semiconductor layer 108 can be reduced by supplying the oxygen to the channel forming region of the semiconductor layer 108. can.

[0194] FIG. 9 shows an enlarged cross-sectional view of a region P surrounded by a dashed line in FIG. 8(B).

[0195] The insulating layer 110 has a region 110d containing the above-mentioned impurity element. The region 110d is located at least near the interface with the region 108n. In a region where the insulating layer 108 is not provided and does not overlap with the conductive layer 112, at least the insulating layer 10 8(B), (C) and 9, The region 110d is not provided in a portion that contacts the channel formation region of the semiconductor layer 108. It is preferable.

[0196] The insulating layer 103 contains the above-described impurity element near the interface where the insulating layer 103 contacts the insulating layer 110. 9, the region 103d is connected to the region 108n. In this case, impurities in the area overlapping with the region 108n may be formed near the interface between the region 108n and the impurities in the area overlapping with the region 108n. The concentration of the substance is lower than that in the portion in contact with the insulating layer 110.

[0197] Here, the impurity concentration in the region 108n increases as it approaches the insulating layer 110. It is preferable that the upper part of the region 108n has a concentration gradient such that the resistance becomes lower toward the upper part. Therefore, the contact resistance with the conductive layer 120a (or the conductive layer 120b) can be reduced more effectively. In addition, compared to the case where the density is uniform across the entire region 108n, Since the total amount of impurities in 8n can be reduced, the influence of heat during the manufacturing process can be reduced. The amount of impurities that can diffuse into the region can be kept low.

[0198] The impurity concentration in the region 110d increases as it approaches the semiconductor layer 108. It is preferable that the insulating layer has a concentration gradient that is large enough to release oxygen when heated. In the edge layer 110, the region 110d to which the impurity element is added has a higher conductivity than the other regions. Therefore, the interface between the insulating layer 110 and the region 108n can be suppressed. The adjacent region 110d acts as a blocking layer for oxygen, and the region 108 The oxygen supplied to n can be effectively reduced.

[0199] As will be described later, the process of adding impurity elements to the regions 108n and 110d is a conductive process. This can be done using the layer 112 as a mask, so that the formation of the region 108n can be performed simultaneously. Region 110d can be formed in a self-aligned manner.

[0200] 9 and other figures, the portion of the insulating layer 110 with a high impurity concentration is To exaggerate the proximity of the semiconductor layer 110, region 110d is shown as a region of the semiconductor layer 110. Although the hatched pattern is only shown near the insulating layer 110, The impurity element is contained throughout the entire thickness direction.

[0201] The region 108n and the region 110d each have an impurity concentration of 1×10 19 atoms / cm 3 That's it, 1 x 10 23 atoms / cm 3 Less than or equal to 5 x 10 19 atoms / cm 3 That's it, 5 x 10 22 atoms / cm 3 Less than 1×10, more preferably 20 at oms / cm 3 That's it, 1 x 10 22 atoms / cm 3 It is preferred to include areas that are: Furthermore, the region 108n has a higher impurity concentration than the region 110d of the insulating layer 110. It is preferable that the region 108n has a component, because the electrical resistance of the region 108n can be more effectively reduced.

[0202] The concentrations of impurities contained in the regions 108n and 110d are measured by, for example, secondary ion mass spectrometry. Secondary Ion Mass Spectrometry (SIMS) and , X-ray Photoelectron Spectroscopy (XPS) When XPS analysis is used, By combining ion sputtering from the front or back side with XPS analysis, The concentration distribution in the thickness direction can be seen.

[0203] In the region 108n, the impurity element is preferably present in an oxidized state. For example, impurity elements such as boron, phosphorus, magnesium, aluminum, and silicon may be used. It is preferable to use an element that is easily oxidized. Since it can bond with oxygen in 108 and exist stably in an oxidized state, it can be used at high temperatures ( For example, even if temperatures exceed 400°C, 600°C, or 800°C, Furthermore, the impurity element removes oxygen from the semiconductor layer 108, Many oxygen vacancies are generated in the region 108n. These oxygen vacancies are combined with hydrogen in the film, This makes the region 108n a carrier supply source, and the region 108n is in an extremely low resistance state.

[0204] When a high-temperature process is performed in a later step, the film may be heated from the outside or the film near the region 108n. If too much oxygen is supplied to the region 108n, the resistance may increase. Therefore, when performing a high-temperature process, the insulating layer 1 having a high barrier property against oxygen is required. It is preferable to treat the material while it is covered with 16.

[0205] Also in the region 110d, the impurity element is preferably present in an oxidized state. Such easily oxidizable elements bond with oxygen in the insulating layer 110 and remain in an oxidized state. Because it can exist stably, it is prevented from desorbing even when exposed to high temperatures in later processes. In particular, the insulating layer 110 contains oxygen (also called excess oxygen) that can be desorbed by heating. In this case, the excess oxygen and the impurity element are bonded and stabilized, so that the region 110d It is possible to suppress the supply of oxygen to the region 108n. The region 110d containing the pure element is in a state where oxygen is difficult to diffuse. It is also possible to prevent oxygen from being supplied to the region 108n from above through the region 110d. This can be done.

[0206] For example, when boron is used as an impurity element, the impurity contained in the region 108n and the region 110d is The boron in the sample can exist in a state bonded to oxygen. This is evident from the XPS analysis of B2 This can be confirmed by observing the spectral peaks due to O3 bonds. In this case, no spectral peaks due to the existence of elemental boron are observed. or the peak intensity is so small that it is buried in the background noise at the lower limit of measurement. It gets smaller.

[0207] The insulating layer 116 and the insulating layer 118 function as a protective layer to protect the transistor 200. In addition, either the insulating layer 116 or the insulating layer 118 may be formed by the insulating layer 110. It is preferable that the oxide or the like has a function of preventing oxygen from diffusing to the outside. Inorganic insulating materials such as nitrides can be used. More specifically, silicon nitride silicon nitride oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, Using inorganic insulating materials such as aluminum nitride, hafnium oxide, and hafnium aluminate It is possible.

[0208] In this example, the protective layer has a laminated structure of an insulating layer 116 and an insulating layer 118. However, if either the insulating layer 116 or the insulating layer 118 is unnecessary, it may not be provided. .

[0209] Here, the semiconductor layer 108 and oxygen vacancies that may be formed in the semiconductor layer 108 will be described. do.

[0210] The oxygen vacancies formed in the semiconductor layer 108 are problematic because they affect the transistor characteristics. For example, when oxygen vacancies are formed in the semiconductor layer 108, hydrogen bonds to the oxygen vacancies. When a carrier source is generated in the semiconductor layer 108, This causes a change in the electrical characteristics of the transistor 200, typically a shift in the threshold voltage. Therefore, it is preferable that the semiconductor layer 108 have as few oxygen vacancies as possible.

[0211] Therefore, in one aspect of the present invention, the insulating film near the semiconductor layer 108, specifically, the semiconductor The insulating layer 110 located above the dielectric layer 108 and the insulating layer 103 located below are made of oxide. The insulating layer 103 and the insulating layer 110 may be partially or completely removed by heat during the manufacturing process. By transferring oxygen to the semiconductor layer 108, oxygen vacancies in the semiconductor layer 108 can be reduced.

[0212] Furthermore, the semiconductor layer 108 preferably has a region in which the atomic ratio of In is greater than the atomic ratio of M. The higher the atomic ratio of In, the more the field-effect mobility of the transistor can be improved. Cut.

[0213] In the case of metal oxides containing In, Ga, and Zn, the bonding strength between In and oxygen is greater than that between Ga and oxide. Therefore, when the atomic ratio of In is large, oxygen deficiency occurs in the metal oxide film. In addition, even if the metal element shown above as M is used instead of Ga, the same problem occurs. When there are many oxygen vacancies in the metal oxide film, the electrical characteristics of the transistor tend to deteriorate. This can lead to degradation and reduced reliability.

[0214] However, in one embodiment of the present invention, the semiconductor layer 108 containing a metal oxide contains a very large amount of Since oxygen can be supplied, it is possible to use metal oxide materials with a large atomic ratio of In. This allows for extremely high field-effect mobility, stable electrical characteristics, and high reliability. It is possible to realize a transistor having such a structure.

[0215] For example, the atomic ratio of In is 1.5 times or more, or 2 times or more, or Preferably, a metal oxide having a molten metal content of 3 times or more, 3.5 times or more, or 4 times or more is used. It is possible.

[0216] In particular, the atomic ratio of In, M, and Zn in the semiconductor layer 108 is In:M:Zn=5:1. : 6 or its vicinity (when In is 5, M is 0.5 or more and 1.5 or less, and Zn is 5 It is preferable that the ratio of the number of In, M, and Zn atoms is 7 or more (including 7 or less). It is preferable that the composition of the semiconductor layer 108 is In:M:Zn=4:2:3 or a value close to that. As the composition, the ratio of the number of atoms of In, M, and Zn in the semiconductor layer 108 may be approximately equal. That is, the ratio of the number of In, M, and Zn atoms is In:M:Zn=1:1:1 or It may also include nearby materials.

[0217] For example, the above-mentioned high field effect mobility transistor is used as a gate driver for generating a gate signal. By using this as a driver, it is possible to provide a display device with a narrow frame width (also called a narrow frame). In addition, the above-mentioned transistors with high field effect mobility are used in the source driver (especially the source It can be used for a demultiplexer connected to the output terminal of the shift register of the driver. As a result, it is possible to provide a display device with a small number of wires connected to the display device.

[0218] Even if the semiconductor layer 108 has a region in which the atomic ratio of In is greater than the atomic ratio of M, However, if the crystallinity of the semiconductor layer 108 is high, the field-effect mobility may be reduced. The crystallinity of 108 can be determined by, for example, X-ray diffraction (XRD). or by transmission electron microscopy (TEM). This can be analyzed using a TEM (Electron Microscope).

[0219] Here, impurities such as hydrogen or moisture mixed into the semiconductor layer 108 may cause transistor characteristics Therefore, in the semiconductor layer 108, hydrogen or water The fewer impurities such as silicon dioxide, the better. By using a thin film, a transistor having excellent electrical characteristics can be fabricated. By reducing the impurity concentration and the defect level density (reducing oxygen vacancies), The carrier density can be reduced. The electrical characteristics of a transistor are such that the threshold voltage is negative (also known as normally on). In addition, a transistor using such a metal oxide film has a significantly low off-state current. Small characteristics can be obtained.

[0220] The semiconductor layer 108 may have a stacked structure of two or more layers.

[0221] For example, the semiconductor layer 108 may be formed by stacking two or more metal oxide films having different compositions. For example, when an In-M-Zn oxide is used, the number of atoms of In, M, and Zn is The ratio is In:M:Zn=5:1:6, In:M:Zn=4:2:3, In:M:Zn=1 :1:1, In:M:Zn=2:2:1, In:M:Zn=1:3:4, In:M:Zn =1:3:2 or a film formed using a sputtering target with a ratio of approximately It is preferable to use two or more laminated layers.

[0222] In addition, the semiconductor layer 108 may be formed by stacking two or more metal oxide films having different crystallinity. In this case, by using the same oxide target and changing the film formation conditions, It is preferable that they are formed continuously without touching each other.

[0223] For example, the oxygen flow rate during the deposition of the first metal oxide film is set to be equal to the oxygen flow rate during the deposition of the second metal oxide film. The oxygen flow rate ratio is set to be smaller than that during the formation of the first metal oxide film. During film formation, oxygen is not allowed to flow. This prevents oxygen from flowing during film formation of the second metal oxide film. In addition, the first metal oxide film is more resistant to the oxidation than the second metal oxide film. On the other hand, the second layer provided on the upper side has a lower crystallinity and a higher electrical conductivity. The second metal oxide film is made to have higher crystallinity than the first metal oxide film, thereby Damage during processing of the insulating layer 08 and during deposition of the insulating layer 110 can be suppressed.

[0224] More specifically, the oxygen flow rate ratio during the formation of the first metal oxide film is set to 0% or more and less than 50%. Preferably, it is 0% or more and 30% or less, more preferably 0% or more and 20% or less, and typically 10%. The oxygen flow rate ratio during the formation of the second metal oxide film is set to 50% or more and 100% or less, preferably Preferably, it is 60% or more and 100% or less, more preferably, 80% or more and 100% or less, and even more preferably The first metal oxide film is preferably 90% or more and 100% or less, and typically 100%. The conditions for forming the first metal oxide film and the second metal oxide film, such as pressure, temperature, and power, may be different. By keeping the conditions other than the oxygen flow rate the same, the time required for the film formation process can be shortened. This is preferable.

[0225] By adopting such a configuration, the transistor 200 has excellent electrical characteristics and high reliability. This can be achieved.

[0226] The above is the explanation of the first configuration example.

[0227] [Configuration example 2] Below, a configuration example of a transistor with a part of its configuration different from that of the above-mentioned Configuration Example 1 will be described. In the following, explanations of parts that overlap with the above-mentioned configuration example 1 may be omitted. In the drawings shown below, parts having the same functions as the above-mentioned configuration example are shown with hatched patterns. In some cases, the same line is used and no symbol is assigned.

[0228] 10A is a top view of a transistor 200A, and FIG. 10B is a top view of a transistor 200B. 10(C) is a cross-sectional view of the channel of the transistor 200A in the channel length direction. FIG. 1 is a cross-sectional view in the width direction of the panel.

[0229] The transistor 200A has a conductive layer 107 between the substrate 109 and the insulating layer 103. The main difference from the transistor 100 illustrated in Configuration Example 1 is that the conductive layer 107 is a semiconductor The layer 108 and the conductive layer 112 overlap with each other.

[0230] In the transistor 200A, the conductive layer 107 is a first gate electrode (bottom gate electrode). The conductive layer 112 functions as a second gate electrode (also referred to as a top gate electrode). A part of the insulating layer 103 functions as a first gate insulating layer. A portion of the insulating layer 110 functions as a second gate insulating layer.

[0231] A portion of the semiconductor layer 108 overlapping with at least one of the conductive layer 112 and the conductive layer 107 , which functions as a channel forming region. The portion of the conductive layer 112 of the conductive film 8 is sometimes called a channel forming region. The area (including the area 108n) that does not overlap with the layer 112 but overlaps with the conductive layer 107 is also A channel can be formed.

[0232] 10(C), the conductive layer 107 is formed by the metal oxide layer 114 and the insulating layer 11. 0, and electrically connected to the conductive layer 112 through an opening 142 provided in the insulating layer 103. This allows the conductive layer 107 and the conductive layer 112 to be given the same potential. This can be done.

[0233] The conductive layer 107 is made of the same material as the conductive layer 112, the conductive layer 120a, or the conductive layer 120b. In particular, when a material containing copper is used for the conductive layer 107, the wiring resistance can be reduced. This is preferable because it can be done easily.

[0234] As shown in FIGS. 10A and 10C, the conductive layer 11 2 and the conductive layer 107 preferably protrude outward beyond the edge of the semiconductor layer 108. At this time, as shown in FIG. 10(C), the entire semiconductor layer 108 in the channel width direction is insulated. The structure is covered with the conductive layer 112 and the conductive layer 107 via the edge layer 110 and the insulating layer 103. .

[0235] With this configuration, the semiconductor layer 108 is subjected to an electric field generated by the pair of gate electrodes. In this case, the conductive layer 107 and the conductive layer 112 are electrically surrounded by the same material. It is preferable to apply a potential to the semiconductor layer 108. This induces a channel in the semiconductor layer 108. Since the electric field can be effectively applied, the on-current of the transistor 200A can be increased. This also makes it possible to miniaturize the transistor 200A.

[0236] The conductive layer 112 and the conductive layer 107 may not be connected to each other. A constant potential is applied to one of the gate electrodes of the transistor 200A, and a signal for driving the transistor 200A is applied to the other gate electrode. At this time, the potential applied to one of the gate electrodes of the transistor 200 It is also possible to control the threshold voltage when A is driven by the other gate electrode.

[0237] This concludes the description of configuration example 2.

[0238] This embodiment mode can be combined with other embodiment modes as appropriate.

[0239] (Embodiment 3) In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to FIGS. ) and Figures 12(A), (B), (C), (D), and (E).

[0240] The electronic devices of this embodiment each include the display device of one embodiment of the present invention in a display portion. This allows the display unit of the electronic device to display high quality images. The display can be performed with high reliability.

[0241] The display unit of the electronic device of this embodiment can display, for example, full high definition, 2K, 4K, 8K, It is possible to display images with a resolution of 16K or higher. The screen size is 20 inches or more diagonally, 30 inches or more diagonally, 50 inches or more diagonally, It can be 60 inches or more, or 70 inches or more diagonally.

[0242] Examples of electronic devices that can use the display device of one embodiment of the present invention include televisions, computer equipment, desktop or notebook personal computers, computer equipment Monitors such as digital signage, In addition to electronic devices with relatively large screens such as large game consoles, digital cameras digital cameras, digital photo frames, mobile phones, portable game consoles, A display device according to one embodiment of the present invention can be used in a variety of applications, including a portable information terminal, a sound player, and the like. Portable electronic devices, wearable electronic devices, VR (Virtual Reality) Also suitable for AR (Augmented Reality) devices, etc. It can be used.

[0243] The electronic device of one embodiment of the present invention may include a secondary battery and may be powered by wireless power transmission. It is preferable that the secondary battery can be charged.

[0244] As the secondary battery, for example, a lithium polymer battery (lithium ion battery) using a gel electrolyte is used. Lithium-ion secondary batteries such as lithium-ion polymer batteries, nickel-metal hydride batteries, nickel-cadmium batteries, organic Examples include radical batteries, lead-acid batteries, secondary air batteries, nickel-zinc batteries, and silver-zinc batteries. do.

[0245] The electronic device according to one embodiment of the present invention may include an antenna. By doing so, it is possible to display images, information, etc. on the display unit. If the device has a secondary battery, the antenna may be used for contactless power transmission.

[0246] The electronic device according to one embodiment of the present invention includes a sensor (force, displacement, position, velocity, acceleration, angular velocity, rotation Number, distance, light, liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, current, voltage, power (including the ability to measure radiation, flow rate, humidity, gradient, vibration, odor or infrared) It may have.

[0247] The electronic device of one embodiment of the present invention can have various functions. (still images, videos, text images, etc.) on the display, touch panel function, calendar Functions such as displaying date and time, running various software (programs) functions, wireless communication functions, and functions to read programs or data recorded on recording media. It can have functions etc.

[0248] Furthermore, in an electronic device having a plurality of display units, one display unit is mainly used for displaying image information. and one display unit mainly displays text information, or multiple displays By displaying images that take parallax into consideration, it is possible to have a function for displaying a three-dimensional image. Furthermore, electronic devices with an image receiving unit have the function of taking still or moving images, Functions for automatically or manually correcting captured images, and for storing captured images on a recording medium (external or electronic) It can have functions such as saving the captured image to a memory card (built into the device) and displaying the captured image on the display. Note that the functions of the electronic device of one embodiment of the present invention are not limited to those described above, and various functions can be used. can have:

[0249] FIG. 11(A) shows a television device 1810. The television device 1810 is The device has a display unit 1811, a housing 1812, a speaker 1813, and the like. Operation keys (including power switch or operation switch), connection terminals, various sensors, micro It can have a phone etc.

[0250] The television device 1810 can be operated by a remote control 1814. .

[0251] The television device 1810 can receive broadcast waves from terrestrial or satellite sources. In addition, broadcasting waves include analog broadcasting, digital broadcasting, etc. There are also broadcasts of video and audio, or audio only. For example, UHF band (approx. 30 0MHz to 3GHz) or a specific frequency in the VHF band (30MHz to 300MHz) It can receive broadcast waves transmitted in several frequency bands. By using multiple received data, the transfer rate can be increased and more information can be transmitted. This allows you to display images with a resolution that exceeds full high definition. For example, 4K, 8K, 16K, or more can be displayed on the display unit 1811. It is possible to display an image having a resolution of 1000 sq.m.

[0252] In addition, the Internet, LAN (Local Area Network), Wi-Fi transmitted via data transmission technology over a computer network, such as i (registered trademark) The image to be displayed on the display unit 1811 may be generated using the broadcast data. In this case, the television device 1810 does not need to have a tuner.

[0253] FIG. 11(B) shows a digital signage 1820 attached to a cylindrical pole 1822. The digital signage 1820 includes a display unit 1821.

[0254] The larger the display area 1821, the more information can be displayed at once. The wider the display part 1821, the more easily it will be noticed by people, and for example, the more effective the advertisement will be. can.

[0255] By applying a touch panel to the display unit 1821, still images or moving images can be displayed on the display unit 1821. It is preferable because it not only displays route information but also allows users to operate it intuitively. When used to provide information such as road traffic information, intuitive operation is required. This can further improve usability.

[0256] FIG. 11C shows a notebook personal computer 1830. The computer 1830 includes a display unit 1831, a housing 1832, a touchpad 1833, and a connection It has port 1834 etc.

[0257] The touchpad 1833 can be used as a pointing device, pen tablet, or other input means. It functions as a touchscreen and can be operated with a finger or a stylus.

[0258] In addition, a display element is incorporated into the touch pad 1833. As shown in FIG. By displaying input keys 1835 on the surface of the touchpad 1833, 1833 can be used as a keyboard. At this time, when you touch the input key 1835, A vibration module is built into the touchpad 1833 to provide a tactile sensation through vibration when the touchpad is pressed. It may be included.

[0259] 12(A) and (B) show a mobile information terminal 800. The mobile information terminal 800 is The device includes a body 801, a housing 802, a display portion 803, a display portion 804, a hinge portion 805, and the like.

[0260] The housing 801 and the housing 802 are connected by a hinge part 805. The mobile information terminal 800 is 12(A) to the folded state, as shown in FIG. 12(B), the housing 801 The housing 802 can be opened.

[0261] For example, document information can be displayed on the display unit 803 and the display unit 804. In addition, the display units 803 and 804 can display still images and moving images. You can also display the image.

[0262] In this way, the portable information terminal 800 can be folded when carried around, making it suitable for general use. It is highly usable.

[0263] The housings 801 and 802 are provided with a power button, an operation button, an external connection port, a switch, and a It may also have a speaker, microphone, etc.

[0264] An example of a mobile information terminal is shown in FIG. 12(C). The mobile information terminal 810 shown in FIG. 12(C) is , a housing 811, a display unit 812, an operation button 813, an external connection port 814, a speaker 81 5, a microphone 816, a camera 817, etc.

[0265] The mobile information terminal 810 has a touch sensor on the display unit 812. All operations, such as inputting characters, can be performed by touching the display 812 with a finger or a stylus. This can be done.

[0266] In addition, by operating the operation button 813, the power can be turned on and off, and the display unit 812 can be displayed. You can change the type of image displayed. For example, from the email creation screen, you can change the type of image displayed. You can switch to the new screen.

[0267] In addition, a detection device such as a gyro sensor or an acceleration sensor is installed inside the mobile information terminal 810. By providing this, the orientation (portrait or landscape) of the mobile information terminal 810 can be determined and the image of the display unit 812 can be displayed. You can also set the screen orientation to automatically change. The switching can be done by touching the display unit 812, operating the operation button 813, or using the microphone 816. This can also be done by voice input or the like.

[0268] The mobile information terminal 810 is, for example, one selected from a telephone, a notebook, an information viewing device, etc. Or it has multiple functions. Specifically, it can be used as a smartphone. The portable information terminal 810 can be used for, for example, mobile phone calls, e-mails, viewing and creating documents, playing music, and video. It can run various applications such as image playback, internet communication, and games. Cut.

[0269] 12D shows an example of a camera. The camera 820 includes a housing 821, a display portion 822, The camera 820 has an operation button 823, a shutter button 824, etc. A lens 826 is attached.

[0270] Here, the camera 820 is a camera in which the lens 826 can be removed from the housing 821 and replaced. However, the lens 826 and the housing 821 may be integrated.

[0271] The camera 820 takes still or moving images by pressing the shutter button 824. The display unit 822 has a function as a touch panel, and It is also possible to take a picture by touching 22.

[0272] The camera 820 can be equipped with a strobe device, a viewfinder, etc. Alternatively, these may be incorporated into the housing 821.

[0273] FIG. 12E shows an example in which the display device of one embodiment of the present invention is mounted as an in-vehicle display. The display unit 832 and the display unit 833 show navigation information, a speedometer, a tachometer, and so on. By displaying meters, mileage, fuel gauge, gear status, air conditioning settings, etc., various The display can be adjusted to suit the user's preferences. The display device according to one embodiment of the present invention can be used in a wide temperature range. This allows for highly reliable display in both low-temperature and high-temperature environments. Therefore, by using the display device of one embodiment of the present invention as an in-vehicle display, This can improve driving safety.

[0274] 13A and 13B and 14A and 14B show a display device according to one embodiment of the present invention. The applied display system is shown.

[0275] FIG. 13A is a perspective view of a display system, which includes a display device 910, a display The image pickup device 911 is disposed behind the display device 910. The image of the other party is displayed on screen 912. The display system shown in FIGS. is sometimes called a videophone device.

[0276] Since the display device 910 has a function of transmitting visible light, The image capturing device 911 can be used to capture an image of the interlocutor 913 .

[0277] The interlocutor 913 is on the side of the first display surface 912 and is positioned so that the line of sight of the image of the other party is aligned with the first display surface 912. Furthermore, in the imaging device 911, specifically, the photographing lens 914 The image pickup device 911 is placed so as to be in the line of sight of the speaker 913. 13 is within a distance range where imaging is possible, and the focus needs to be positioned on the interlocutor 913. be.

[0278] FIG. 13B shows a top view of the videophone device, which includes a display device 910, an imaging device 911, The first display screen 912 is shown. The interlocutor 913 faces the first display screen 912. In the image captured by the imaging device 911, the other interlocutor aligns his / her line of sight with the line of sight of the interlocutor 913. It is possible.

[0279] Furthermore, this display system allows the user to view the image displayed on the first display surface 912, and further In the example shown in FIG. The speaker 913 looks at the image displayed on the first display surface 912 and sits behind the display device 910. It is possible to observe the state of a passerby 915 on the other side. 14A is a corresponding top view. Note that the configuration shown in FIG. As shown in FIGS. 14A and 14B, the display system displays an image on a first display surface 912. This allows for the creation of an image that combines the image captured with the information behind it.

[0280] As described above, an electronic device can be obtained by applying a display device of one embodiment of the present invention. The display device has an extremely wide range of applications and can be used in electronic devices in all fields.

[0281] This embodiment mode can be combined with other embodiment modes as appropriate. [Explanation of symbols]

[0282] FPCa: Flexible printed circuit board, FPCb: Flexible printed circuit board, GD_L: Gate driver, GD_R: Gate driver, GL_m: Scan line, GL_m+ 1: Scan line, IC: Integrated circuit, P: Area, SL_n: Signal line, TCOM: Common wiring, VC OM: common wiring, 10: display device, 11: pixel, 11a: pixel, 11b: pixel, 30: backplane black light unit, 31: substrate, 32: substrate, 33: light emitting element, 34: diffusion plate, 35: Printed circuit board, 36: path, 37: path, 38: light-shielding layer, 39: light guide plate, 41: conductive layer, 42: liquid crystal layer, 43b: conductive layer, 43c: conductive layer, 44: insulating layer, 46a: conductive layer, 46 b: conductive layer, 46c: conductive layer, 46d: conductive layer, 61: polarizing plate, 63: polarizing plate, 100: Display area, 101: transistor, 102: transistor, 103: insulating layer, 104: capacitor 105: capacitance element; 106: liquid crystal element; 107: conductive layer; 108: semiconductor layer; 08n: region, 109: substrate, 110: insulating layer, 110d: region, 111: region, 112 : conductive layer, 116: insulating layer, 118: insulating layer, 120a: conductive layer, 120b: conductive layer, 1 21: Wiring, 122: Wiring, 124: Wiring, 125: Wiring, 135: Overcoat, 1 41: adhesive layer, 141a: opening, 141b: opening, 172: FPC, 200: transformer 200A: transistor, 211: insulating layer, 213: insulating layer, 214: insulating layer, 215: insulating layer, 221a: conductive layer, 221b: conductive layer, 222a: conductive layer, 222c: Conductive layer, 223a: conductive layer, 223b: conductive layer, 225: insulating layer, 231a: semiconductor layer, 231a_1: Semiconductor layer, 231a_m: Semiconductor layer, 231ai: Area, 231an: Low Resistance region, 231b: semiconductor layer, 242: connector

Claims

[Claim 1] a transistor, a first conductive layer, a second conductive layer, and a third conductive layer; The channel width of the transistor is 30 μm or more and 1000 μm or less, the transistor has a plurality of semiconductor layers; the number of the plurality of semiconductor layers is greater than 2 and less than or equal to 50; each of the plurality of semiconductor layers has a channel formation region, a first region, and a second region; In each of the plurality of semiconductor layers, the channel formation region is disposed between the first region and the second region when viewed from above, the channel formation region of each of the plurality of semiconductor layers includes a metal oxide; the metal oxide contains at least indium or zinc; the channel formation region of each of the plurality of semiconductor layers has a region overlapping with the first conductive layer, the first region overlaps the second conductive layer but does not overlap the first conductive layer; the second region overlaps the third conductive layer but does not overlap the first conductive layer; the third conductive layer has a function of transmitting visible light, A display device in which the second region and the third conductive layer in a stacked state have a function of transmitting visible light.

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