Indication device

Abstract

To provide high-definition display devices, low-power consumption display devices, highly reliable display devices, and highly visible display devices. [Solution] The display device includes a transistor 102 having a metal oxide, a first conductive layer 221a, a second conductive layer 222a, and a third conductive layer 223a. The channel width of the transistor is 30 μm or more and 1000 μm or less. The transistor has a semiconductor layer 231a that is greater than 2 and less than or equal to 50. Each semiconductor layer has a first region 231an, a second region 231ai, and a channel-forming region sandwiched between the first region 231an and the second region 231ai when viewed from above. The channel-forming region has a region that overlaps with the first conductive layer. The first region overlaps with the second conductive layer and does not overlap with the first conductive layer, and the second region overlaps with the third conductive layer and overlaps with the first conductive layer. In the semiconductor layer, the stacked second region and the third conductive layer have the function of transmitting visible light.

Description

[Technical Field]

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

[0002] Furthermore, one aspect of the present invention is not limited to the above-described technical field. Examples include semiconductor devices, display devices, light-emitting devices, energy storage devices, memory devices, electronic devices, and lighting devices. Input devices (e.g., touch sensors), input / output devices (e.g., touch panels), Examples of such driving methods or manufacturing methods can be given. [Background technology]

[0003] As a display device, flat panel displays, such as liquid crystal displays and light-emitting displays, The first option is widely used. Patent Document 1 shows an example of a pixel section and drive circuit for a display device. It is.

[0004] In recent years, a technology has also been developed to use transistors made of metal oxides as pixels in display devices. Patent Document 2 describes a transistor using a metal oxide as a semiconductor material for a display device. Technology for use in pixel switching elements and the like has been disclosed. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-052634 [Patent Document 2] Japanese Patent Publication No. 2011-227477 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] One aspect of the present invention aims to provide a high-resolution display device. One aspect of the present invention aims to provide a display device with low power consumption. One aspect of the present invention aims to provide a highly reliable display device. One aspect of this invention aims to provide a display device with high visibility.

[0007] Alternatively, one aspect of the present invention aims to provide a liquid crystal display device with a high aperture ratio. Alternatively, one aspect of the present invention aims to provide a high-definition liquid crystal display device. .

[0008] Furthermore, the description of these problems does not preclude the existence of other problems. One aspect of the present invention It is not necessary to solve all of these issues. Specifications, drawings, requests It is possible to extract other issues from the description of the requested terms. [Means for solving the problem]

[0009] One aspect of the present invention is a transistor, a first conductive layer, a second conductive layer, and a third conductive layer. The transistor has the following characteristics, and the channel width of the transistor is 30 μm or more and 1000 μm or less. The transistor has multiple semiconductor layers, and the number of semiconductor layers is greater than 2 and less than or equal to 50. Each of the multiple semiconductor layers has a channel formation region, a first region, and a second region. Furthermore, in each of the multiple semiconductor layers, the channel formation region, when viewed from the top, is the first region Located between the first and second regions, each of the multiple semiconductor layers has a channel-forming region The region contains a metal oxide, and the metal oxide contains at least indium or zinc, and multiple Each of the semiconductor layers has a channel formation region that has a region overlapping with the first conductive layer. The first region overlaps with the second conductive layer and does not overlap with the first conductive layer. The second region overlaps with the third conductive layer and does not overlap with the first conductive layer. The third conductive layer transmits visible light and the second region and the third conductive layer in the stacked state have the function of transmitting visible light. A display device having the function of transmitting visible light.

[0010] Also, in the above configuration, 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] Also, in the above configuration, the first region functions as one of the source region and the drain region of the transistor and the second region functions as the other of the source region and the drain region of the transistor. The first region and the second region have a lower electrical resistance than the channel formation region and preferably the first region and the second region contain boron or phosphorus.

[0012] Also, in the above configuration, the display device preferably has the function of displaying by a field sequential drive method. Preferably.

[0013] Also, in the above configuration, the display device has a liquid crystal element, and the liquid crystal element is a light-scattering type liquid crystal element and preferably the liquid crystal element scatters light when in the on state and transmits light when in the off state. Preferably.

Advantages of the Invention

[0014] According to one aspect of the present invention, a high-definition display device can be provided. Also, according to one aspect of the present invention, a display device with low power consumption can be provided. Also, according to one aspect of the present invention A more reliable display device can be provided. Furthermore, according to one aspect of the present invention, This allows us to provide a display device with high visibility.

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

[0016] Furthermore, the description of these effects does not preclude the existence of other effects. One aspect of the present invention It is not necessarily required to have all of these effects. Furthermore, it is possible to extract effects other than those mentioned above. [Brief explanation of the drawing]

[0017] [Figure 1] A diagram showing an example of the display module configuration. [Figure 2] (A) is a circuit diagram showing an example of pixel configuration. (B) is a cross-sectional view showing an example of pixel configuration. [Figure 3] (A) is a top view showing an example of pixel configuration. (B) is a top view showing an example of pixel configuration. (C) is a top view showing an example of a partial pixel configuration. (D) is a top view showing an example of pixel configuration. [Figure 4] A top view showing an example of a transistor configuration. [Figure 5] (A) is a circuit diagram showing an example of pixel configuration. (B) is a timing chart explaining the operation. (C) is a timing chart explaining the operation. [Figure 6] A top view showing an example of pixel configuration. [Figure 7] (A) is a cross-sectional view showing an example of pixel configuration. (B) is a cross-sectional view showing an example of pixel configuration. [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] Cross-section 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] (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. [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] (A) is a diagram showing an example of a display system. (B) is a diagram showing an example of a display system. [Figure 14] (A) is a diagram showing an example of a display system. (B) is a diagram showing an example of a display system. [Modes for carrying out the invention]

[0018] Embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description. Without departing from the spirit and scope of the present invention, its form and details may be modified in various ways. Those skilled in the art will readily understand what is possible. Therefore, the present invention is as shown in the following embodiments. It should not be interpreted as being limited to the contents described herein.

[0019] In the configuration of the invention described below, the same part or part having a similar function is The same reference numerals are used consistently across different drawings, and explanations of their repetition are omitted. When referring to the function of [this], the hatch pattern is the same, and sometimes no specific symbol is assigned.

[0020] Furthermore, the position, size, and scope of each component shown in the drawings are, for the sake of ease of understanding, actual The position, size, and range of the edges may not be shown. Therefore, the disclosed invention is not necessarily However, this is not limited to the location, size, and scope disclosed in the drawings.

[0021] Note that the words "membrane" and "layer" may differ in meaning depending on the context or situation. Therefore, they can be interchanged. For example, the term "conductive layer" can be replaced with "conductive film." It is possible to change the term to "insulating film". Alternatively, for example, the term "insulating film" can be changed to It is possible to change the term to "insulating layer".

[0022] (Embodiment 1) In this embodiment, a display device according to one aspect of the present invention will be described with reference to Figures 1 to 7. .

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

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

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

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

[0027] Pixel 11 can also be called a subpixel. For example, a subpixel that exhibits red light, a subpixel that exhibits green light, etc. A single pixel unit is composed of subpixels and subpixels that exhibit blue color, thus display In region 100, full-color display is possible. The sub-pixels exhibit the color red, Not limited to green and blue. Pixel units may include, for example, white, yellow, magenta, or cyan. Sub-pixels exhibiting colors such as the above may be used. Note that in this specification, sub-pixels are not simply referred to as pixels. It may be noted.

[0028] The display device consists of a scan line drive circuit (gate driver) and a signal line drive circuit (source driver). It may also incorporate one or more of the following: a drive circuit for a touch sensor. One or more of these may be externally attached. The display device shown in Figure 1 is gated It has a built-in driver, and an integrated circuit IC with a source driver is attached externally.

[0029] Of the gate drivers GD_L and GD_R, one controls the pixels in odd-numbered rows. One has a function to control one row, and the other has a function to control pixels in even-numbered rows. For example, the pixel in the mth row. It is connected to scan line GL_m and controlled by gate driver GD_L. Also, m+ The pixels in the first row are connected to scan line GL_m+1 and controlled by gate driver GD_R. The nth signal line SL_n is electrically connected to the gate driver GD_L of the pixel. Pixels 11 and pixels 11 that are electrically connected to the gate driver GD_R are connected alternately. By providing gate drivers on two opposing sides, one gate driver can be used to... The spacing of the connected wiring can be widened. Also, the gate driver can be installed on only one side. When this is done, the area that is not visible on that side becomes larger. For this reason, the gate driver By dividing the display into two sections, the non-display area on each side of the display device can be narrowed, resulting in a narrower bezel.

[0030] Gate drivers GD_L and GD_R are flexible printed circuits. Signals and power are supplied from the outside via the FPGA on the substrate. The integrated circuit IC has a flexible Signals and power are supplied externally via a blueprinted circuit board (FPCb).

[0031] An example of the circuit configuration of pixel 11 will be explained using Figure 2(A). Figure 2(A) The pixel 11a shown has a transistor 102 and a capacitive element 105.

[0032] Either the source or drain of transistor 102 is connected to one electrode of capacitive element 105. It is electrically connected.

[0033] Furthermore, it is preferable that the display element be electrically connected in parallel or in series with the capacitive element 105. It seems so. Examples of display elements include liquid crystal elements, organic EL elements, LED elements, and MEMS (Mi Examples include elements of cro (Electro-Mechanical Systems). .

[0034] Here, one of the sources or drains of transistor 102 and one of the capacitive elements 105 Let the node to which one electrode is connected be node NA.

[0035] The gate of transistor 102 is electrically connected to wiring 121. Transistor 10 The other end of either the source or drain of 2 is electrically connected to the wiring 124.

[0036] Wiring 121 can be called a scan line and has the function of controlling the operation of the transistor. Wiring 124 functions as a signal line that supplies image signals.

[0037] By using a transistor with extremely low off-current for transistor 102, the node NA is reduced. The potential can be maintained for a long time. The transistor can, for example, use a metal oxide. The transistor used in the channel formation region (hereinafter referred to as OS transistor) can be used. .

[0038] Alternatively, the transistors in the pixels have silicon in the channel formation region. A transistor (hereinafter referred to as a Si transistor) may also be used. As a Si transistor, amorphous Transistors with crystalline silicon (typically low-temperature polysilicon) Examples include transistors made of single-crystal silicon.

[0039] For example, when rewriting the image signal every frame period, an OS transistor can be used. Si transistors may also be used. It is necessary to maintain the potential of node NA for a long time. In such cases, it is preferable to use OS transistors rather than Si transistors.

[0040] <Pixel top surface layout> An example of the transistor 102 and capacitive element 105 in pixel 11a is shown in Figure 2. This will be explained using B) and Figure 3.

[0041] Figure 3(A) shows an example of a top view of transistor 102 and capacitive element 105. 2(B) shows a cross-section corresponding to the dashed line CD shown in Figure 3(A). Capacitive element 105 is It is electrically connected to the transistor 102 via the conductive layer 41, etc.

[0042] Transistor 102 consists of a semiconductor layer 231a, a conductive layer 223a, and a conductive layer 221a. It has a conductive layer 222a and a conductive layer 46c. Capacitive element 105 has a conductive layer 46b and It can be composed of an electrical layer 41 and an insulating layer 44 sandwiched between two conductive layers. It is preferable that layer 223a and conductive layer 221a function as gate electrodes. 223a is stacked with the semiconductor layer 231a, with an insulating layer 225, which functions as a gate insulating film, in between. The conductive layer 221a is positioned with an insulating layer 211, which functions as a gate insulating film, sandwiched between them. It is arranged in lamination with the conductive layer 231a. The conductive layer 223a and conductive layer 221a are connected to the conductive layer 22 An opening 303 is provided in the layer sandwiched between 3a and the conductive layer 221a, and is electrically connected. That's fine.

[0043] In Figure 3(A), conductive layer 223a and conductive layer 221a are electrically charged by the opening 303. They are electrically connected, and the conductive layer 221a is used as wiring that extends to other areas, such as adjacent pixels. It is used as a wire. Conductive layer 223a may be used instead of conductive layer 221a. Layer 221a has a region that intersects with conductive layer 222a when viewed from above, for example. By using 1a as the wiring, multiple Because an insulating layer can be placed and the physical distance between conductive layers can be increased, short circuit This offers advantages such as being less prone to occurrence and allowing for smaller parasitic capacity.

[0044] The conductive layer 222a is disposed on the semiconductor layer 231a via an insulating layer. In particular, the conductive layer 2 22a is placed on the low-resistance region of the semiconductor layer 231a. The insulating layer has an opening 301. The conductive layer 222a is provided. The conductive layer 222a is electrically in contact with the semiconductor layer 231a at the opening 301. It is preferable that this is continued. Furthermore, the conductive layer 222a is provided so as to fill the opening 301. It is preferable that the semiconductor layer 231a is in a region that overlaps with the conductive layer 223a. It has 31ai and two low-resistance regions 231an. The two low-resistance regions 231an are When viewed from above, the conductive layer 223a is sandwiched between them. Region 231ai is channel-forming It is preferable that it functions as a region. One of the two low-resistance regions 231an is the source region. The other side preferably functions as a drain region. The low-resistance region of the semiconductor layer is, for example, water Element, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, arsenic, aluminum, or noble gases, etc. It contains impurity elements. In particular, it is preferable to contain boron or phosphorus. It may contain two or more of these.

[0045] The conductive layer 41 is placed on the conductive layer 46b and the conductive layer 46c via an insulating layer. In the insulating layer, an opening 304 is provided in the region that overlaps with the conductive layer 46c. It is preferable that 1 is electrically connected to the conductive layer 46c at the opening 304. The conductive layer 41 is provided so as to cover the opening 302.

[0046] Figure 3(B) is shown without the conductive layer 41 in Figure 3(A) for better visibility. This is a top view of the case where... Also, Figure 3(C) shows a conductive layer 222a, a conductive layer 46c, and a conductive layer... This is a top view in which layer 46b, opening 301, opening 302, etc. are not shown. Conductive layer 46 c is placed on the semiconductor layer 231a via an insulating layer. In particular, the conductive layer 46c is a semiconductor It is placed on the low-resistance region 231an of layer 231a. The insulating layer is provided with an opening 302. The conductive layer 46c is electrically connected to the semiconductor layer 231a at the opening 302. This is preferable. Furthermore, 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 either the source or the drain of transistor 102. The conductive layer 46c is then electrically connected to the source and drain of transistor 102. It will be done.

[0048] By using an OS transistor as transistor 102, the semiconductor layer 231a The semiconductor layer 231a, etc., can be configured to have the function of transmitting visible light. By incorporating impurity elements, the semiconductor layer retains its ability to transmit visible light. It can reduce resistance.

[0049] The semiconductor layer 231a, conductive layer 46c, conductive layer 46b, and conductive layer 41 transmit visible light. It is preferable to use a material that transmits visible light. By forming the capacitive element 105, the region 111 shown in Figure 3(A) transmits visible light. It can be a functional area. By using the configuration of one aspect of the present invention, the upper surface The area of ​​region 111 as seen from this perspective can be made larger. Therefore, the aperture ratio of the pixels can be increased. This can be done. By increasing the aperture ratio, the light extraction efficiency (or pixel transmittance) can be increased. This allows for a reduction in the power consumption of the display device. This can improve the quality of the display at the location.

[0050] The transistor 102 shown in Figure 3(A) is electrically connected to its source and drain. One end of the wiring can be constructed with a conductive layer 222a and the other end with a conductive layer 46c, as shown in Figure 2(B As shown in the cross-section, each conductive layer is formed on a different layer via an insulating layer. Compared to forming each conductive layer in the same layer, the distance between conductive layers when viewed from above is greater It can sometimes be made smaller. For example, as shown in Figure 3(D), the conductive layer 222a is from the top surface By having a region that overlaps with conductive layer 223a, the wiring width of conductive layer 222a can be made wider. This can be done. For example, by increasing the width of the wiring, wiring resistance can be reduced. This allows for improved performance of the display device.

[0051] By widening the channel width of transistor 102, the current drive of transistor 102 The dynamic capability is improved, and the charging speed to the capacitive element 105 is improved. On the other hand, the transistor 102 Increasing the channel width increases the area occupied by transistor 102 in the pixel, and the aperture The rate may decrease. Here, channel width refers, for example, to the width of the channel formation region.

[0052] By using the configuration of one aspect of the present invention, the channel width of transistor 102 is wide. In some cases, a higher aperture ratio can be achieved.

[0053] The capacity can be increased by using the configuration of one aspect of the present invention. Therefore, Even when using liquid crystal materials with high dielectric constants, excellent response speeds can be achieved. .

[0054] The semiconductor layer of the transistor may be composed of multiple island-shaped semiconductor layers. (Figure) 4. The semiconductor layer 231a of transistor 102 is composed of multiple island-shaped semiconductor layers. An example is shown. The semiconductor layer 231a shown in Figure 4 has m layers (where m is between 2 and 50). Preferably an integer between 3 and 20, and more preferably between 3 and 10, in the form of an island-shaped semiconductor. It is composed of layers 231a_1 to 231a_m. By forming multiple island-shaped semiconductor layers... This can sometimes make heat dissipation easier. Therefore, it helps to suppress the temperature rise during transistor operation. It can sometimes be controlled. This can improve the reliability of the transistor.

[0055] The channel width of transistor 102 is, for example, the distance between the semiconductor layers of transistor 102. In the region overlapping with the gate electrode, looking from the top surface, from the source region to the drain region This is the width in the direction roughly perpendicular to the direction of travel.

[0056] If transistor 102 has multiple island-shaped semiconductor layers, then transistor 102 The channel width is, for example, the sum of the widths of each island-shaped semiconductor layer. The width of the semiconductor layer is, for example, 2 μm to 300 μm, or 3 μm to 200 μm. Alternatively, it can be between 5 μm and 100 μm, or between 10 μm and 50 μm. Also, The width of each island-shaped semiconductor layer is, for example, 100 times the channel length of transistor 102. Smaller, more preferably less than 50 times, and even more preferably less than 25 times.

[0057] When using the configuration shown in Figure 4 as transistor 102, the channel width is, for example, 30μ. m to 1000 μm, or 30 μm to 500 μm, or 50 μm or more It is 350 μm or less.

[0058] <Example of display device configuration> Using Figures 5(A), (B), (C), Figure 6, and Figure 7(A), (B), two pixels An example configuration of a display device having a transistor and two capacitive elements will be described.

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

[0060] This 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. This correction allows, for example, Furthermore, liquid crystal elements can express more gradations than can be expressed using only image signals. It is possible.

[0061] Furthermore, this correction allows the liquid crystal elements to be driven at a voltage higher than the output voltage of the source driver. It can be moved. Within a pixel, the voltage supplied to the liquid crystal element can be changed to a desired value. Therefore, existing source drivers can be used, eliminating the cost of designing new source drivers. This can reduce the amount of noise and also suppress the output voltage of the source driver from becoming too high. This can reduce the power consumption of the source driver.

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

[0063] Furthermore, because high voltage can be applied to drive the liquid crystal elements, liquid crystals exhibiting the blue phase can be produced. For example, it is possible to use liquid crystal materials with high driving voltages, thus broadening the range of liquid crystal material choices. can.

[0064] Furthermore, because high voltage can be applied to drive the liquid crystal elements, By temporarily increasing the voltage to rapidly change the orientation of the liquid crystal, the liquid crystal is subjected to overdrive. It can also improve response speed.

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

[0066] In one embodiment of the present invention, the supplied image signal is not changed, and a correction signal is supplied. Pixels can generate new image signals. External devices can be used to generate the new image signals themselves. Compared to generating the original, this reduces the load on external devices. Furthermore, it also allows for a new approach. The process of generating an image signal with pixels can be performed in a small number of steps, and the number of pixels is large. It can also be used with display devices that have a short horizontal period.

[0067] <Circuit> Figure 5(A) shows the circuit diagram of pixel 11b.

[0068] Pixel 11b consists of transistor 101, transistor 102, capacitive element 104, and capacitive element It has 105 and a liquid crystal element 106.

[0069] Either the source or drain of transistor 101 is connected to one electrode of capacitive element 104. They are electrically connected. The other electrode of the capacitive element 104 is connected to the source of the transistor 102. The drain is connected to one electrode of the capacitive element 105 and one electrode of the liquid crystal element 106. They are connected electrically.

[0070] Here, one of the sources or drains of transistor 101 and one of the capacitive elements 104 The node to which the electrodes are connected is called node NS. The other electrode of the capacitive element 104, the transient One of the source or drain of the sta 102, one electrode of the capacitive element 105, and the liquid crystal element Let node NA be the node to which one of the electrodes of 106 is connected.

[0071] The gate of transistor 101 is electrically connected to wiring 122. Transistor 10 The gate of transistor 2 is electrically connected to wiring 121. The source or gate of transistor 101 The other end of the rain is electrically connected to wiring 125. The source of transistor 102 or The other end of the drain is electrically connected to wiring 124.

[0072] The other electrode of the capacitive element 105 and the other electrode of the liquid crystal element 106 are connected via a common wiring. It is electrically connected to VCOM and common wiring TCOM. Each of the TCOM lines can be supplied with any desired potential.

[0073] Wiring 121 and wiring 122 can each be called scan lines, and they control the operation of the transistor. It has a control function. Wiring 125 functions as a signal line that supplies an image signal. Wiring 124 functions as a signal line for writing data to node NA.

[0074] Each transistor shown in Figure 5(A) has a gate and a back gate that are electrically connected. However, the connection of the back gate is not limited to this. Also, the back gate of the transistor It is not necessary to set it up.

[0075] By making transistor 101 non-conductive, the potential of nodes NS can be maintained. Furthermore, by making transistor 102 non-conductive, the potential of node NA can be maintained. Yes, it is possible. Also, with transistor 102 in a non-conductive state, through transistor 101 By supplying a predetermined potential to node NS, capacitive coupling via the capacitive element 104 occurs. The potential of node NA can be changed in response to changes in the potential of node NS.

[0076] In pixel 11b, the correction signal written to node NA from wiring 124 is transmitted via wiring 12 The image signal supplied from 5 is capacitively coupled and supplied to the liquid crystal element 106. Therefore, The liquid crystal element 106 can display a corrected image.

[0077] By using a transistor with extremely low off-current for transistor 101, the node NS The potential can be maintained for a long time. The transistor in question is, for example, an OS transistor. A transistor can be used. Similarly, a transistor with an extremely low off-current can be used for transistor 102. By using a sta, the potential of node NA can be maintained for a long time. Extremely off-current An example of a low-power transistor is an OS transistor. Also, the pixels have A Si transistor may be used for the transistor. Alternatively, an OS transistor and an S Both i-transistors and i-transistors may be used.

[0078] Alternatively, Si transistors may be applied to the transistors in the pixels. Examples of transistors include those made of amorphous silicon and those made of crystalline silicon (representative). Examples include transistors made of low-temperature polysilicon or single-crystal silicon. .

[0079] For example, if the correction signal and image signal are rewritten every frame period, a transistor OS transistors may be used for transistors 101 and 102, and Si transistors You may use a t-t-t-t-t-t-t-t-n-a Transistors 101 and 102 use OS transistors rather than Si transistors. It is preferable to use a zista.

[0080] <Timing Chart> Using the timing chart shown in Figure 5(B), the correction signal (Vp) at pixel 11b This explains the operation of writing to node NA. When the purpose is to correct the image signal (Vs), It is preferable to write the positive signal Vp at the end of each frame period. Note that the wiring 124 is The supplied correction signal (Vp) can be any positive or negative signal, but here This explains the case where a positive signal is supplied. Also, in the following explanation, a high potential is referred to as "H". Low potential is represented by "L".

[0081] At time T1, the potential of wire 121 is "H", the potential of wire 122 is "L", and the potential of wire 124 is If we set this to "L" and the potential of wiring 125 to "L", then transistor 102 conducts, and node N The potential of A becomes the potential of wiring 124. At this time, the potential of wiring 124 is reset to the reset potential (for example) By setting it to "L", the operation of the liquid crystal element 106 can be reset.

[0082] Prior to time T1, the display operation of the liquid crystal element 106 during the previous frame period is performed. It is in that state.

[0083] At time T2, the potential of wire 121 is "L", the potential of wire 122 is "H", and the potential of wire 124 is If we denote the current as "Vp" and the potential of wiring 125 as "L", then transistor 101 conducts, and the capacitance element The potential of one electrode of sub-electrode 104 becomes "L". This operation is performed in order to carry out the subsequent capacitive coupling operation. This is the reset operation.

[0084] At time T3, the potential of wiring 121 is "H", the potential of wiring 122 is "H", and the potential of wiring 124 is If we denote this as "Vp" and the potential of wiring 125 as "L", then the potential of wiring 124 (corrected) will be set at node NA. The signal (Vp) is written.

[0085] At time T4, the potential of wire 121 is "L", the potential of wire 122 is "H", and the potential of wire 124 is If we denote this as "Vp" and the potential of wiring 125 as "L", then transistor 102 becomes non-conductive. The correction signal (Vp) is held at node NA.

[0086] At time T5, the potential of wire 121 is "L", the potential of wire 122 is "L", and the potential of wire 125 is If we set it to "L", transistor 101 becomes non-conductive, and the writing of the correction signal (Vp) The work is finished.

[0087] Next, using the timing chart shown in Figure 5(C), the image signal at pixel 11b ( The correction operation of Vs) and the display operation of the liquid crystal element 106 will be explained. Note that wiring 125 is It is assumed that the desired potential is supplied at the appropriate time.

[0088] At time T11, the potential of wiring 121 is set to "L", the potential of wiring 122 is set to "H", and the potential of wiring 124 is set to "L". If the position is set to "L", transistor 101 conducts, and capacitive coupling with capacitive element 104 causes noise The potential of wiring 125 is added to the potential of node NA. That is, node NA is the image signal ( The potential (Vs) becomes (Vs+Vp)' when the correction signal (Vp) is added to (Vs). +Vp)' also includes potential fluctuations due to capacitive coupling of capacitances between wiring.

[0089] At time T12, the potential of wiring 121 is set to "L", the potential of wiring 122 is set to "L", and the potential of wiring 124 is set to "L". If the position is set to "L", transistor 101 becomes non-conductive, and the potential (Vs+V) is at node NA. p)' is maintained. Then, the liquid crystal element 106 performs a display operation according to the said potential.

[0090] The above explains the correction operation of the image signal (Vs) and the display operation of the liquid crystal element 106. The writing operation of the correction signal (Vp) and the input operation of the image signal (Vs), as explained earlier, are continuous. Alternatively, the correction signal (Vp) may be written to all pixels, followed by the image signal (Vs). You may also perform the input action.

[0091] If no correction operation is performed, the image signal is supplied to wiring 124, and transistor 10 The display operation of the liquid crystal element 106 may be performed by controlling the conductivity and non-conductivity of 2. In this case, transistor 101 may be kept non-conductive at all times, or a constant potential may be supplied to wiring 125. In this state, transistor 101 may be kept constantly conductive.

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

[0093] OS transistors are used as transistors 101 and 102. This provides semiconductor layer 231a and semiconductor layer 231b with a structure that has the function of transmitting visible light. It can be considered a success.

[0094] In Figure 6, the conductive layer 222a of transistor 102 overlaps with the conductive layer 223a. It has a region.

[0095] The transistor 101 shown in Figure 6 consists of a semiconductor layer 231b, a conductive layer 223b, and a conductive layer 2 It has a conductive layer 21b and a conductive layer 222c. Capacitive element 104 has a conductive layer 46a and a conductive layer 4 It can be composed of 1 and an insulating layer 44 sandwiched between the two conductive layers. 1 is a common electrode in capacitive elements 105 and 104.

[0096] In a pixel according to one aspect of the present invention, the capacitive element 104 has a larger capacitance than the capacitive element 105. It is preferable that it has a value. For example, the area of ​​the region where conductive layer 41 and conductive layer 46a overlap is It is preferable that the area is larger than the area of ​​the region where the electrolytic layer 41 and the conductive layer 46b overlap.

[0097] Furthermore, the conductive layer 41 and the conductive layer 43c, which will be described later in Figure 7, also provide a conductive layer. A quantitative element is formed.

[0098] It is preferable that the conductive layer 223b and the conductive layer 221b function as gate electrodes. Furthermore, the conductive layer 223b and the conductive layer 221b are provided in the openings in the layer sandwiched between them. They may be electrically connected.

[0099] The conductive layer 222c is disposed on the semiconductor layer 231b via an insulating layer. In particular, the conductive layer 2 Layer 22c is located on the low-resistance region of the semiconductor layer 231b. The conductive layer 222c is located on the insulating layer It is preferable that the opening provided in the is electrically connected to the semiconductor layer 231b.

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

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

[0102] Here, conductive layer 46a, conductive layer 46b, conductive layer 46c, and conductive layer 41 are semiconductor layers Compared to 231a and semiconductor layer 231b, it transmits visible light more easily. "Easily transparent" means, for example, that the transmittance of visible light is higher. Also, semiconductor layer 2 The channel formation region (e.g., region 231ai) of 31a and semiconductor layer 231b is Low-resistance regions (for example, low-resistance region 231) of semiconductor layer 231a and semiconductor layer 231b Compared to (an), it may transmit visible light more easily.

[0103] Figure 7(A) shows an example of a cross-section of a display device 10 having pixels according to one embodiment of the present invention. AB represents the cross-section corresponding to the dashed line AB shown in Figure 6.

[0104] The display device 10 shown in Figure 7(A) includes a substrate 31 and a transistor 1 provided on the substrate 31. 01 and transistor 102, insulating layer 213 provided on both transistors, insulating layer 2 It has an insulating layer 214 provided on 13 and an insulating layer 215 provided on the insulating layer 214. Furthermore, the display device 10 includes an FPC 172, a connector 242, and a conductive layer provided on the substrate. It has 43b. In the example shown in Figure 7(A), the FPC172 is connected by the connector 242. It is electrically connected to the conductive layer 43b. Furthermore, the conductive layer 43b is formed in the same layer as the conductive layer 222a, etc. It is preferable that this be done.

[0105] Furthermore, the display device 10 shown in Figure 7(A) is a substrate that is positioned facing the substrate 31. It has 32. On the substrate 32, the surface facing the substrate 31 has a light-shielding layer 38, over A coat 135 and a conductive layer 43c are provided in that order.

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

[0107] The display device 10 may also have spacers, alignment films, colored layers, etc.

[0108] Furthermore, the display device 10 shown in Figure 7(A) includes a polarizing plate 61, a polarizing plate 63, and a backlight unit. The backlight unit 30 includes a light-emitting element 33, a diffuser plate 34, and a light guide plate 3 It has 9. If necessary, a light-diffusing lens may be provided on the light-emitting element 33. Here, Figure 7 In (A), the configuration includes polarizing plates 61 and 63, but the display device 10 is The configuration may also be one that does not include both or either of the polarizing plates 61 and 63.

[0109] The insulating layers 211 and 225 that are in contact with the semiconductor layer 231a and semiconductor layer 231b are acid It is preferable that the insulating layer is a chemical insulating layer. In some cases, it is preferable that at least the layer in contact with the semiconductor layer 231a, etc., is an oxide insulating layer. This makes it possible to suppress the occurrence of oxygen vacancies in semiconductor layer 231a, etc., and transistor This can increase its reliability.

[0110] It is preferable that either the insulating layer 213 or the insulating layer 214 is a nitride insulating layer. This prevents impurities from entering the semiconductor layer 231a, etc., thus improving the reliability of the transistor. It can sometimes enhance sexual performance.

[0111] The insulating layer 215 preferably has a planarization function, for example, being an organic insulating layer. This is preferable. Note that the insulating layer 215 does not need to be formed, and a conductive layer is placed in contact with the insulating layer 214. Formation of 46a, etc. is also possible.

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

[0113] It is preferable that substrates 31 and 32 have the function of transmitting visible light. There are no major restrictions on the material of the substrate 32, and various substrates can be used. glass substrates, quartz substrates, sapphire substrates, semiconductor substrates, ceramic substrates, metal substrates, 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 with a thickness sufficient to be flexible, a flexible display device can be realized. can.

[0115] The backlight unit 30 shown in Figure 7(A) guides light through a diffuser plate 34 directly below the pixels. The configuration includes a plate 39. A light-emitting element 33 is provided at the end of the light guide plate 39. Plate 39 has an uneven surface on the side opposite to the diffuser plate 34, and scatters the guided light with this uneven surface. This allows the material to be ejected in the direction of the diffuser plate 34.

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

[0117] Light emitted in the direction of the diffuser plate 34 follows paths such as path 36 and path 37 shown in Figure 7(A). It is ejected through the path towards the substrate 32.

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

[0119] In path 37, light incident from the substrate 31 side passes through the low resistance of the insulating layer 211 and semiconductor layer 231a. Region, conductive layer 46c, conductive layer 41, liquid crystal layer 42, conductive layer 43c, overcoat 135 It is then ejected towards the substrate 32.

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

[0121] The display device 10 can display a color image.

[0122] If the display device 10 has a colored layer, the light source of the backlight unit 30 Of the emitted light, light outside of 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 will appear red. The light emitted from the green subpixels (subpixels) to the outside of the display module is green, and blue The light emitted from the sub-pixels (sub-pixels) to the outside of the display module is blue.

[0123] Furthermore, the backlight unit 30 is configured to sequentially flash three colored light-emitting elements. It can also do this. The display device 10 sequentially flashes three colored light-emitting elements and synchronizes this with... The pixels are driven and color display is performed based on the sequential additive color mixing method. The method can also be called field sequential drive.

[0124] Field sequential drive allows for the display of vivid color images. Furthermore, it is possible to display smooth moving images. Also, by using the above driving method, one There is no need to compose a pixel with multiple subpixels of different colors, and the effective reflective area of ​​a single pixel (effective Because the display area (also called the aperture ratio) can be increased, a brighter display can be achieved. Furthermore, since there is no need to place a color filter on the pixel, the transmittance of the pixel can also be improved. Furthermore, it allows for even brighter displays. Additionally, the manufacturing process can be simplified, reducing production costs. It can be reduced.

[0125] The field sequential drive system is a drive system that performs color display using time division. Specifically, the light-emitting elements of each color, such as red, green, and blue, are lit sequentially with a time delay, The pixels are driven in synchronization with this, and color display is performed based on sequential additive color mixing.

[0126] When applying the field sequential driving method, one pixel is sub-colored with multiple different colors. Because it does not need to be composed of pixels, the aperture ratio of the pixels can be increased. High-resolution images can also be produced. Furthermore, there is no need to provide a coloring layer such as a color filter. This eliminates light absorption by the colored layer, improving the transmittance of the pixels. Because the required brightness can be obtained with less power, low power consumption can be achieved. The manufacturing process for the display device can be simplified, reducing manufacturing costs.

[0127] When applying a field sequential drive method, a high frame rate is required. A display device according to one aspect of the present invention has two capacitive elements in one pixel, so the pixel retention Because it has a large capacity and can supply a high voltage to the liquid crystal elements, the response speed of the liquid crystal elements is improved. It can be improved. For example, by temporarily increasing the voltage applied to the liquid crystal element, the distribution of the liquid crystal can be improved. By using overdrive driving, which rapidly changes direction, the response speed of the liquid crystal elements is improved. Therefore, a display device according to one aspect of the present invention is required to have a high frame frequency. This configuration is suitable for applying a field sequential drive system.

[0128] A low rotational viscosity coefficient in the liquid crystal material is preferable because it allows for a faster response of the liquid crystal element. Specifically, the rotational viscosity coefficient of the liquid crystal material is between 10 mPa·sec and 150 mPa·sec. It is preferable that this be the case.

[0129] In Figure 7(A), the backlight unit 30 uses a light guide plate 39 to illuminate from the substrate 31 side. The configuration was designed to allow light to be incident, but the backlight unit 30 faces the substrate 31 and the pixels are directly in front of it. A configuration in which a light-emitting element 33 is provided below is also possible. For example, a planar light-emitting element facing the substrate 31. It may also be possible to configure it to fit the environment.

[0130] Figure 7(B) shows the electrical connection between the source and drain of transistor 101. An example is shown in which the electrode is formed using conductive layer 46c and conductive layer 46d formed in the same layer. The conductive layer 46d has the function of transmitting visible light. In Figure 7(B), the conductive layer 46d The semiconductor layer 231b that overlaps with it also has the function of transmitting visible light, and the semiconductor layer 231b and the conductive layer In the region where 46d overlaps and does not overlap with conductive layer 223b, the backlight unit The light emitted from the 30 can be directed toward the substrate 32.

[0131] <Materials of the constituent elements> Next, each component of the display device and display module of this embodiment can be used We will provide details about the materials and other aspects.

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

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

[0134] Liquid crystal materials include positive-type liquid crystal materials, where the dielectric anisotropy (Δε) is positive, and negative-type liquid crystal materials, where the dielectric anisotropy (Δε) is negative. There are different types of liquid crystal materials. In one aspect of the present invention, either material can be used and applied. The optimal liquid crystal material can be used depending on the mode and design.

[0135] Display devices can use liquid crystal elements to which various modes are applied. For example, T N mode, FFS mode, IPS mode, ASM (Axially Symmetric) (Micro-cell) mode, OCB (Optically Co (Passenged Birefringence) mode, FLC (Ferroele ctric Liquid Crystal) mode, AFLC (AntiFerroe lectric Liquid Crystal) mode, ECB (Electrica (Controlled Birefringence) mode, VA-IPS model Liquid crystal elements with modes such as guest host mode applied can be used.

[0136] Furthermore, a liquid crystal element is an element that controls the transmission or non-transmission of light through the optical modulation effect of liquid crystals. The optical modulation effect of liquid crystals is due to the electric field acting on the liquid crystal (horizontal electric field, vertical electric field, or It is controlled by an electric field (including an oblique direction). As for the liquid crystal used in the liquid crystal element, thermo Tropical liquid crystal, low molecular liquid crystal, polymer liquid crystal, polymer dispersed liquid crystal (PDLC) Dispersed Liquid Crystal, ferroelectric liquid crystal, antiferroelectric Liquid crystals can be used. Depending on the conditions, these liquid crystal materials can be cholesteric phase, saturates, etc. It exhibits mechtic phase, cubic phase, chiral nematic phase, isotropic phase, etc.

[0137] As described above, the display device of this embodiment drives the liquid crystal elements by applying a high voltage. Therefore, a liquid crystal exhibiting the blue phase may be used. The blue phase is one of the liquid crystal phases, As the temperature of a resteric liquid crystal is increased, it manifests just before the transition from the cholesteric phase to the isotropic phase. This is the blue phase. The blue phase only appears in a narrow temperature range, so to improve the temperature range... A liquid crystal composition containing 5% or more by weight of a chiral agent is used as the liquid crystal layer. A liquid crystal composition containing liquid crystals and a chiral agent exhibits a short response speed and optical isotropy. Furthermore, A liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent does not require alignment treatment and has a wide viewing angle. It has low dependence. Also, since an alignment film does not need to be provided, rubbing treatment is unnecessary, and rubbing This prevents electrostatic discharge (ESD) caused by the scalding process, and the display panel during the manufacturing process. This can reduce defects or damage.

[0138] Furthermore, a light-scattering liquid crystal element may be used as the liquid crystal element. Examples of light-scattering liquid crystal elements include: It is preferable to use an element having a composite material of liquid crystal and polymer. For example, a polymer dispersion liquid Crystal (PDLC(Polymer Dispersed Liquid Crystal) ) elements can be used. Alternatively, polymer network liquid crystal (PNLC (Poly A mer network liquid crystal element may also be used.

[0139] Light-scattering liquid crystal elements have a three-dimensional network structure of liquid crystals in a resin portion sandwiched between a pair of electrodes. It has a structure in which a section is provided. As for the material used for the liquid crystal section, for example, nematic liquid crystal is It can be used. Furthermore, a photocurable resin can be used as the resin part. Examples of fats include monofunctional monomers such as acrylates and methacrylates, and diacrylates. Polyfunctional monomers such as triacrylate, dimethacrylate, and trimethacrylate. Alternatively, polymerizable compounds obtained by mixing these can be used.

[0140] Light-scattering liquid crystal elements utilize the anisotropy of the refractive index of liquid crystal materials to transmit or scatter light. The display is made by [this method]. Furthermore, the resin part may also have refractive index anisotropy. Light-scattering liquid crystal. When liquid crystal molecules align in a certain direction according to the voltage applied to the element, in a certain direction the liquid crystals are aligned in a specific direction. The difference in refractive index between the crystal and resin parts becomes smaller, and light incident along that direction is scattered by the liquid crystal part. It transmits light without being obscured. Therefore, the light-scattering liquid crystal element appears transparent from that direction. It is recognized. On the other hand, when the arrangement of liquid crystal molecules becomes random according to the applied voltage, Because there is no significant change in the refractive index difference between the liquid crystal and resin parts, the incident light is scattered by the liquid crystal part. Therefore, the light-scattering liquid crystal element becomes opaque regardless of the viewing direction.

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

[0142] When using a light-scattering liquid crystal element as the liquid crystal element, for example, the light-scattering liquid crystal element is set to the off state such as, for example, a state where no voltage is applied, or a state where the absolute value of the applied voltage is small and the light is transmitted, and it is set to the on state, that is, when the absolute value of the applied voltage is made larger and the light is scattered. The display device is operated in this mode. With this configuration, a transparent display device can be obtained in the normal state (a state where no display is made). In this case, color display can be performed when the operation of scattering light is performed. Such an operation is sometimes called the reverse mode.

[0143] As the conductive material that transmits visible light, for example, a material containing one or more selected from indium (In), zinc (Zn), and tin (Sn) may be used. Specifically, indium oxide, indium tin oxide (ITO), indium zinc oxide, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium tin oxide containing silicon oxide (ITSO), zinc oxide, zinc oxide containing gallium, etc. can be mentioned. In addition, a film containing graphene can also be used. The film containing graphene can be formed, for example, by reducing a film containing graphene oxide.

[0144] In addition, the 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 include indium, and In-M-Zn oxide (where M is Al, Ti, G It is even more preferable that the element (a, Y, Zr, La, Ce, Nd, Sn, or Hf) be included.

[0145] Oxide semiconductors have oxygen vacancies in the film and, at least, the concentrations of impurities such as hydrogen and water in the film. On the other hand, it is a semiconductor material whose resistance can be controlled by means of an oxide semiconductor. A treatment that increases at least one of oxygen deficiency and impurity concentration in the body layer, or oxygen deficiency and impurity By selecting a treatment that reduces at least one of the concentrations of pure substances, the properties of the oxide conductive layer can be improved. The resistivity can be controlled.

[0146] Furthermore, the oxide conductive layer formed using an oxide semiconductor has a carrier density of Highly resistive, low-resistance oxide semiconductor layer, conductive oxide semiconductor layer, or highly conductive oxide It can also be called a material semiconductor layer.

[0147] The transistors in the display device of this embodiment are either top-gate or bottom-gate type. Any of the following structures may be used. Alternatively, gate electrodes may be provided above and below the channel. This is also acceptable. The semiconductor material used in the transistor is not particularly limited; for example, oxide semiconductors, etc. Examples include lycon and germanium.

[0148] The crystallinity of semiconductor materials used in transistors is not particularly limited; amorphous semiconductors are also available. Crystalline semiconductors (microcrystalline semiconductors, polycrystalline semiconductors, monocrystalline semiconductors, or semiconductors with some crystals) Any semiconductor having regions may be used. If a crystalline semiconductor is used, This is preferable because it suppresses the deterioration of the transistor characteristics.

[0149] For example, using Group 14 elements, compound semiconductors, or oxide semiconductors in the semiconductor layer. Yes, it is possible. Typically, this includes semiconductors containing silicon, semiconductors containing gallium arsenide, or indigo Oxide semiconductors containing um can be applied to semiconductor layers.

[0150] It is preferable to use oxide semiconductors in the semiconductors that form the channels of transistors. It is particularly preferable to use oxide semiconductors with a larger band gap than silicon. This method uses semiconductor materials with a wider band gap and lower carrier density than silicon. This is preferable because it reduces the current when the transistor is off.

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

[0152] Furthermore, its low off-current allows the charge stored in the capacitor via the transistor to be released over a long period of time. It is possible to hold it over time. By applying such transistors to pixels, the surface It also becomes possible to stop the drive circuit while maintaining the gradation of the displayed image. As a result, This makes it possible to realize a display device with reduced power consumption.

[0153] The transistor has an oxide semiconductor layer that has been purified to suppress the formation of oxygen vacancies. This is preferable. This lowers the current value (off-current value) when the transistor is off. This makes it possible to extend the holding time of electrical signals such as image signals. When the power is on, the write interval can also be set to be longer. Therefore, the frequency of refresh operations can be reduced. Since it can be made to do so, it has the effect of suppressing power consumption.

[0154] In addition, a transistor using an oxide semiconductor can obtain a relatively high field-effect mobility, so that high-speed driving is possible. By using such a transistor capable of high-speed driving in a display device, the transistor in the display unit and the transistor in the drive circuit unit can be formed on the same substrate. That is, as a drive circuit, there is no need to separately use a semiconductor device formed by a silicon wafer or the like, so that the number of components of the display device can be reduced. Also, in the display unit, by using a transistor capable of high-speed driving, a high-quality image can be provided.

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

[0156] As an insulating material that can be used for each insulating layer, overcoat, etc. included in the display device, an organic insulating material or an inorganic insulating material can be used. Examples of the organic insulating material include acrylic resin, epoxy resin, polyimide resin, polyamide resin, polyimide amide resin, siloxane resin, benzocyclobutene-based resin, and phenol resin, etc. Examples of the inorganic insulating layer include a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, and nitrogen Silicon oxide film, aluminum oxide film, hafnium oxide film, yttrium oxide film, zirconium oxide Conium film, gallium oxide film, tantalum oxide film, magnesium oxide film, lanthanum oxide film, Examples include cerium oxide films and neodymium oxide films.

[0157] This includes the gate, source, and drain of a transistor, as well as various wirings and electrodes in a display device. The conductive layers include aluminum, titanium, chromium, nickel, copper, yttrium, and zirconium. Metals such as um, molybdenum, silver, tantalum, and tungsten, and materials mainly composed of said metals Using one or more of the alloys as components, the structure is composed of a single layer or a multilayer structure. This is possible. For example, a two-layer structure in which a titanium film is laminated on an aluminum film, or a tungsten film on A two-layer structure in which a titanium film is laminated, a two-layer structure in which a copper film is laminated on a molybdenum film, molybdenum A two-layer structure consisting of a copper film laminated on an alloy film containing tungsten, and copper-magnesium-aluminum. A two-layer structure in which a copper film is laminated on a um alloy film, a titanium film or titanium nitride film, and the titanium film Alternatively, an aluminum film or copper film can be layered on top of a titanium nitride film, and then a titanium film can be added on top of that. A three-layer structure forming a film or titanium nitride film, a molybdenum film or molybdenum nitride film, An aluminum film or copper film is laminated on top of the molybdenum film or molybdenum nitride film. Furthermore, there are three-layer structures in which a molybdenum film or molybdenum nitride film is formed on top of the above. For example, when the conductive layer has a three-layer structure, the first and third layers may be titanium, titanium nitride, and molybdenum. Butene, tungsten, molybdenum and tungsten alloys, molybdenum and zirconium A film is formed using an alloy containing um, or molybdenum nitride, and the second layer is made of copper, aluminum It is preferable to form a film made of a low-resistance material such as gold or silver, or an alloy of copper and manganese. It is important to note that ITO, indium oxide containing tungsten oxide, and tungsten oxide are also included. Indium zinc oxide, indium oxide containing titanium oxide, indium oxide containing titanium oxide Using light-transmitting conductive materials such as um tin oxide, indium zinc oxide, and ITSO Alternatively, an oxide conductive layer may be formed by controlling the resistivity of the oxide semiconductor. .

[0158] A silicon nitride film is preferred for the insulating layer 44, which functions as a dielectric for the capacitive element.

[0159] The adhesive layer 141 may be a thermosetting resin, a photocuring resin, or a two-component curable resin. Curable resins can be used. For example, acrylic resin, urethane resin, epoxy resin Fat or siloxane resin can be used.

[0160] As the connector 242, for example, an anisotropic conductive film (ACF) c Conductive Film), or anisotropic conductive paste (ACP: Anis You can use otropic conductive paste, etc.

[0161] A colored layer is a colored layer that transmits light in a specific wavelength range. Materials that can be used for colored layers. Examples include metal materials, resin materials, and resin materials containing pigments or dyes. ru.

[0162] The light-shielding layer 38 is provided, for example, between adjacent colored layers of different colors. For example, a metal material A black matrix formed using a resin material containing a material, or a pigment or dye. It can be used as a light-shielding layer 38. Note that the light-shielding layer 38 is used for the drive circuit section and other parts of the display section. Providing it in the outer region is preferable because it can suppress light leakage such as waveguide light.

[0163] The backlight unit 30 includes a direct-lit backlight and an edge-lit backlight. Light sources such as LEDs (Light Emitting Diodes) can be used. 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 produced by sputtering. Chemical vapor deposition (CVD) Methods include vacuum deposition and pulsed laser deposition (PLD). ition) method, Atomic Layer Deposition (ALD) method n) It can be formed using methods such as the CVD method. PECVD:Plasma Enhanced Chemical Vapor Dep Examples include the ostition method and the thermal CVD method. An example of the thermal CVD method is organometallation One example is the Metal Organic Vapor Deposition (MOCVD) method.

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

[0166] The thin films that make up the display device can be processed using photolithography or the like. Alternatively, an island-like thin film may be formed by a film deposition method using a shielding mask. Thin films are processed using methods such as the noimprint method, sandblasting method, or lift-off method. This is also good. As a 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 to remove the resist mask, and a photosensitive A method of forming a thin film, then exposing and developing it to process the thin film into a desired shape. , there is.

[0167] In photolithography, the light used for exposure is, for example, the i-line (wavelength 365n). m), g-line (wavelength 436nm), h-line (wavelength 405nm), and light obtained by mixing these are Other options include using ultraviolet light, KrF laser light, or ArF laser light. This is also possible. Furthermore, exposure may be performed using immersion lithography. The light used for exposure is polar Examples include extreme ultraviolet (EUV) light and X-rays. Furthermore, an electron beam can be used instead of the light used for exposure. Extreme ultraviolet light, X Using a wire or electron beam is preferable because it allows for extremely fine processing. When exposure is performed by scanning a beam such as a sub-beam, a photomask is not required. be.

[0168] Thin film etching methods include dry etching, wet etching, and sandblasting. Laws and other regulations can be used.

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

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

[0171] [Configuration Example 1] Figure 8(A) is a top view of transistor 200, and Figure 8(B) is shown in Figure 8(A). This corresponds to a cross-sectional view of the cross-section along the dashed line A1-A2, and Figure 8(C) is shown in Figure 8(A). This corresponds to a cross-sectional view of the cross-section along the dashed line B1-B2. Note that in Figure 8(A), Some components of the transistor 200 (such as the gate insulating layer) are omitted from the illustration. The direction of the dashed line A1-A2 is the channel length direction, and the direction of the dashed line B1-B2 is the channel width direction. It corresponds to Figure 8(A) in the following drawings as well. Similarly, some of the components will be omitted from the illustration.

[0172] The transistor 200 is provided on the substrate 109 and has an insulating layer 103, a semiconductor layer 108, and an insulating layer 103. It has an edge layer 110, a metal oxide layer 114, a conductive layer 112, an insulating layer 116, an insulating layer 118, etc. The island-shaped semiconductor layer 108 is provided on the insulating layer 103. The insulating layer 110 is provided on the insulating layer 1 It is provided in contact with the upper surface of 03, the upper surface and side surface of the semiconductor layer 108, and the metal oxide layer 114 and The conductive layer 112 is stacked on the insulating layer 110 in this order and superimposed on the semiconductor layer 108. It has a portion that is the upper surface of the insulating layer 110, the side surface of the metal oxide layer 114, The insulating layer 118 is provided covering the upper and side surfaces of the conductive layer 112. It is installed to cover 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 insulating layer. It functions as a marginal layer. Transistor 200 has a gate electrode provided on semiconductor layer 108. This is a so-called top-gate type transistor.

[0174] Furthermore, as shown in Figures 8(A) and (B), the transistor 200 is on the insulating layer 118. It may have conductive layers 120a and conductive layers 120b. 20b functions as the source electrode and drain electrode. Conductive layer 120a and conductive layer 120 b are openings 14 provided in the insulating layer 118, insulating layer 116, and insulating layer 110, respectively. 1a and the opening 141b are electrically connected to the region 108n, which will be described later.

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

[0176] For example, semiconductor layer 108 is made of indium and M (where M is gallium, aluminum, and silicon). N, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel Germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium (One or more elements selected from luminous, tantalum, tungsten, or magnesium), It is preferable that it contains zinc. In particular, M is aluminum, gallium, yttrium, or It is preferable to use one or more types selected from tin.

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

[0178] The semiconductor layer 108 may consist of layers with different compositions, layers with different crystallinity, or layers with different impurity concentrations. A laminated structure in which different layers are stacked may also be used.

[0179] The conductive layer 112 and the metal oxide layer 114 are processed so that their upper surface shapes are roughly identical to each other. It is being done.

[0180] In this specification, "approximately matching top surface shape" means that there is a small difference between the stacked layers. This refers to the overlapping of parts of the outlines. For example, the upper layer and the lower layer may have the same mask pattern. , or including cases where part of it is processed with the same mask pattern. However, strictly speaking, ring The outlines do not overlap, the outline of the upper layer is located within the inner outline of the lower layer, or the outline of the upper layer is located within the lower layer It may also be located outside the contour, in which case it is also said that "the top shape is roughly the same."

[0181] The metal oxide layer 114 located between the insulating layer 110 and the conductive layer 112 is in the insulating layer 110. It functions as a barrier film that prevents the contained oxygen from diffusing to the conductive layer 112. The oxide layer 114 allows hydrogen and water contained in the conductive layer 112 to diffuse towards the insulating layer 110. It also functions as a barrier film to prevent this. The metal oxide layer 114 is, for example, at least the insulating layer 11 Materials that are less permeable to oxygen and hydrogen than 0 can be used.

[0182] The metal oxide layer 114 makes it easier for the conductive layer 112 to attract oxygen such as aluminum and copper. Even when using a metallic material, oxygen will diffuse from the insulating layer 110 to the conductive layer 112. This can prevent the conductive layer 112 from containing hydrogen. This prevents hydrogen from diffusing from the insulating layer 110 to the semiconductor layer 108. As a result, the carrier density in the channel formation region of the semiconductor layer 108 is made extremely low. It is possible.

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

[0184] As the metal oxide layer 114, an insulating material with a higher dielectric constant than silicon oxide is used. This is preferred. In particular, an aluminum oxide film, a hafnium oxide film, or a hafnium aluminum film is preferred. Using a film or similar material is preferable because it allows for a reduction in the driving voltage.

[0185] For example, the metal oxide layer 114 may be indium oxide or indium tin oxide (ITO). or conductive oxides such as silicon-containing indium tin oxide (ITSO) It can also be used. Conductive oxides containing indium are particularly preferred due to their high conductivity. .

[0186] Furthermore, the metal oxide layer 114 may contain one or more of the same elements as the semiconductor layer 108. It is preferable to use a material. In particular, an oxide semiconductor material applicable to the semiconductor layer 108 is preferable. It is preferable to use the same material as the semiconductor layer 108 as the metal oxide layer 114. By applying a metal oxide film formed using a puttering target, the equipment can be standardized. This is preferable because it allows for this.

[0187] Alternatively, both the semiconductor layer 108 and the metal oxide layer 114 may contain indium and gallium. When using a metal oxide material, the metal oxide layer 114 is more durable than the semiconductor layer 108. When a material with a high um composition ratio (content) is used, the metal oxide layer 114's relationship to oxygen This is preferable because it can further enhance blocking properties. In this case, the semiconductor layer 108 is By using a material with a higher indium composition ratio than the material of the metal oxide layer 114, This can increase the field-effect mobility of the 200 inverter.

[0188] Furthermore, the metal oxide layer 114 is preferably formed using a sputtering apparatus. When forming an oxide film using a sputtering apparatus, the film is formed in an atmosphere containing oxygen gas. This allows for the appropriate addition of oxygen to the insulating layer 110 and the semiconductor layer 108.

[0189] The semiconductor layer 108 consists of a region superimposed on the conductive layer 112 and a pair of low-resistance regions flanking that region. It has region 108n. The region of the semiconductor layer 108 that overlaps with the conductive layer 112 is a transistor. Region 200 functions as a channel formation region. On the other hand, region 108n is transistor 200 It functions as either a source or drain area.

[0190] Furthermore, region 108n is a region with lower resistance and higher carrier concentration than the channel-forming region. This can also be referred to as a region with a high oxygen defect density, a region with a high impurity concentration, or a region that is n-type. It is possible.

[0191] Region 108n of the semiconductor layer 108 is a region containing impurity elements. For example, hydrogen, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, arsenic, aluminum, Examples include noble gases. Representative examples of noble gases include helium, neon, and aluminum. Examples include ion, krypton, and xenon. It is particularly preferable that they contain boron or phosphorus. Furthermore, it may contain two or more of these elements.

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

[0193] Furthermore, the insulating layer 103 and insulating layer 110 that are in contact with the channel formation region of the semiconductor layer 108, It is preferable to use an oxide film. For example, silicon oxide film, silicon oxide nitride film, oxide An oxide film such as an aluminum film can be used. This allows transistor 200 During the manufacturing process, such as heat treatment, oxygen that has been removed from the insulating layer 103 and insulating layer 110 is used to make semiconductors By supplying oxygen to the channel formation region of the body layer 108, oxygen vacancies in the semiconductor layer 108 can be reduced. can.

[0194] Figure 9 shows an enlarged cross-sectional view of the region P enclosed by the dashed line in Figure 8(B).

[0195] The insulating layer 110 has a region 110d containing the aforementioned impurity elements. Region 110d is It is located at least near the interface with region 108n. Region 110d is located in semiconductor layer 1 In a region where 08 is not provided and does not overlap with the conductive layer 112, at least the insulating layer 10 It is also located near the interface with 3. Furthermore, as shown in Figures 8(B), (C) and 9, Region 110d is not provided in the portion that is in contact with the channel formation region of the semiconductor layer 108. It is preferable.

[0196] Furthermore, the insulating layer 103 contains the aforementioned impurity elements near the interface where it contacts the insulating layer 110. It has region 103d. Also, as shown in Figure 9, region 103d is adjacent to region 108n. It may also be provided near the interface. In this case, the impurity in the portion overlapping with region 108n. The concentration of the substance will be lower than that of the part in contact with the insulating layer 110.

[0197] Here, the concentration of impurities in region 108n increases as it gets closer to the insulating layer 110. It is preferable to have a concentration gradient. This results in lower resistance towards the top of region 108n. Therefore, the contact resistance with the conductive layer 120a (or conductive layer 120b) is reduced more effectively. This can be done. Also, compared to the case where the concentration is uniform throughout the entire region 108n, region 10 Because the total amount of impurities in 8n can be reduced, channel formation is less affected by heat and other factors during the manufacturing process. This allows us to keep the amount of impurities that can diffuse into the region low.

[0198] Furthermore, the concentration of impurities in region 110d increases as it approaches the semiconductor layer 108. It is preferable to have a concentration gradient. An oxide film that can release oxygen by heating is applied to the insulator. In the marginal layer 110, the region 110d where the aforementioned impurity elements are added is compared to the other regions. This suppresses the release of oxygen. Therefore, at the interface with region 108n of the insulating layer 110, The nearby region 110d acts as a blocking layer against oxygen, and region 108 This can effectively reduce the amount of oxygen supplied to n.

[0199] As will be described later, the process of adding impurity elements to regions 108n and 110d is conductive Layer 112 can be used as a mask. This allows for the formation of region 108n simultaneously with the formation of the region 108n. Region 110d can be formed in a self-consistent manner.

[0200] In Figure 9, etc., the portion of the insulating layer 110 with a high impurity concentration is the interface with the semiconductor layer 108. To exaggerate the fact that it is located in the vicinity, the region 110d is shown with a hatching pattern only in the vicinity of the semiconductor layer 1 in the insulating layer 1 08, but actually the above impurity elements are contained throughout the thickness direction of the insulating layer 110.

[0201] The regions 108n and 110d each have an impurity concentration of 1×10 19 atoms / cm 3 or more and 1×10 23 atoms / cm 3 or less, preferably 5×10 19 atoms / cm 3 or more and 5×10 22 atoms / cm 3 or less, more preferably 1×10 20 at oms / cm 3 or more and 1×10 22 atoms / cm 3 or less, and preferably includes regions. Also, if the region 108n has a portion with a higher impurity concentration than the region 110d of the insulating layer 110, it is preferable because the electrical resistance of the region 108n can be made lower more effectively.

[0202] The concentrations of the impurities contained in the regions 108n and 110d can be analyzed by, for example, secondary ion mass spectrometry (SIMS: Secondary Ion Mass Spectrometry) or , X-ray photoelectron spectroscopy (XPS: X-ray Photoelectron Spectr oscopy), or other analytical methods. When using XPS analysis, by combining ion sputtering from the front surface side or the back surface side with XPS analysis, the concentration distribution in the depth direction can be known.

[0203] ​​​Furthermore, in region 108n, it is preferable that impurity elements exist in an oxidized state. For example, impurity elements include boron, phosphorus, magnesium, aluminum, and silicon. It is preferable to use easily oxidizable elements. Such easily oxidizable elements are used in semiconductor layers. Because it can exist stably in an oxidized state by bonding with oxygen in 10⁸, it can be subjected to high temperatures in subsequent processes. For example, even if temperatures exceeding 400°C, 600°C, or 800°C are applied, Desorption is suppressed. Also, impurity elements remove oxygen from semiconductor layer 108, Many oxygen vacancies are generated in region 108n. These oxygen vacancies combine with hydrogen in the membrane. As a result, region 108n becomes a carrier source, resulting in extremely low resistance.

[0204] Furthermore, when performing processes that involve high temperatures in later stages, the film near the outer or region 108n may be affected. If a large amount of oxygen is supplied to region 10⁸n, the resistance may increase. Therefore, when performing processes involving high temperatures, an insulating layer with high barrier properties against oxygen is required. It is preferable to process the material while it is covered with 16.

[0205] Furthermore, in region 110d, it is preferable that impurity elements exist in an oxidized state. Such easily oxidized elements combine with oxygen in the insulating layer 110 and remain in an oxidized state. Because it can exist stably, desorption is suppressed even when high temperatures are applied in subsequent processes. Furthermore, the insulating layer 110 contains oxygen (also called excess oxygen) that can be released by heating. In this case, the excess oxygen and the impurity element combine and stabilize, so from region 110d This can suppress the supply of oxygen to region 108n. Region 110d, which contains pure elements, is a state where oxygen does not easily diffuse, therefore region 110d This also prevents oxygen from being supplied to region 108n from above via region 110d. It is possible.

[0206] For example, when boron is used as an impurity element, it is contained in regions 108n and 110d. Boron can exist in a state of being bonded with oxygen. This is why, in XPS analysis, B2 This can be confirmed by observing spectral peaks caused by O3 bonding. Furthermore, XPS analysis can also be performed. In this case, no spectral peaks are observed that are caused by the element boron existing in its elemental form. or the peak intensity is so small that it is buried in the background noise at the lower limit of measurement. It will bloom.

[0207] The insulating layers 116 and 118 function as protective layers to protect the transistor 200. Furthermore, either the insulating layer 116 or the insulating layer 118 may be released from the insulating layer 110. It is preferable that the material has a function to prevent the oxygen from diffusing to the outside. For example, an oxide or Inorganic insulating materials such as nitrides can be used. A more specific example is silicon nitride. N, silicon nitride, silicon oxide nitride, aluminum oxide, aluminum oxide nitride, Using inorganic insulating materials such as aluminum nitride, hafnium oxide, and hafnium aluminate It is possible.

[0208] Here, we show a case where the protective layer is a laminated structure consisting of insulating layer 116 and insulating layer 118. However, either the insulating layer 116 or the insulating layer 118 may be omitted if it is not needed. .

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

[0210] Oxygen vacancies formed in semiconductor layer 108 are problematic because they affect transistor characteristics. For example, when an oxygen vacancy is formed in the semiconductor layer 108, hydrogen is bonded to the oxygen vacancy. , can become a carrier source. When a carrier source is generated in semiconductor layer 108, The electrical characteristics of the 200 change, typically resulting in a shift in the threshold voltage. Therefore, in the semiconductor layer 108, the fewer oxygen vacancies there are, the better.

[0211] Therefore, in one embodiment of the present invention, the insulating film near the semiconductor layer 108, specifically the semiconductor The insulating layer 110 located above the body layer 108, and the insulating layer 103 located below it, are oxide Includes a film. Due to heat during the manufacturing process, the insulating layer 103 and insulating layer 110 are converted to the semiconductor layer 108. By transferring oxygen to the semiconductor layer 108, it becomes possible to reduce oxygen vacancies in the semiconductor layer 108.

[0212] Furthermore, it is preferable that the semiconductor layer 108 has a region where the atomic ratio of In is greater than the atomic ratio of M. The higher the ratio of In atoms, the better the field-effect mobility of the transistor can be. Cut.

[0213] Here, in the case of metal oxides containing In, Ga, and Zn, the bonding force between In and oxygen is stronger than that between Ga and acid. Because it is weaker than the elemental bonding force, when the atomic ratio of In is large, oxygen deficiency occurs in the metal oxide film. Damage is easily formed. The same applies when the metal element indicated by M above is used instead of Ga. There is a tendency for this to occur. When there are many oxygen vacancies in the metal oxide film, the electrical characteristics of the transistor are affected. This can lead to a decline in performance or a decrease in reliability.

[0214] However, in one aspect of the present invention, a very large amount of metal oxide is contained in the semiconductor layer 108. Because oxygen can be supplied, it becomes possible to use metal oxide materials with a large atomic ratio of In. This results in an extremely high field-effect mobility, stable electrical characteristics, and high reliability. It is possible to realize a transistor equipped with this feature.

[0215] For example, if the atomic ratio of In is 1.5 times or more, or 2 times or more, compared to the atomic ratio of M, Alternatively, metal oxides that are three times or more, 3.5 times or more, or four times or more are preferably used. It is possible.

[0216] In particular, the ratio of the number of In, M, and Zn atoms in semiconductor layer 108 is set to In:M:Zn=5:1 : 6 or its vicinity (If In is 5, M is 0.5 or greater and 1.5 or less, and Zn is 5) It is preferable to have a ratio of 7 or less (including 7 or less). Alternatively, the ratio of the number of atoms of In, M, and Zn is It is preferable that In:M:Zn = 4:2:3 or a similar ratio. Also, semiconductor layer 108 As for the composition, the ratio of the number of In, M, and Zn atoms in the semiconductor layer 108 may be made approximately equal. i. That is, the ratio of the number of atoms of In, M, and Zn is In:M:Zn=1:1:1 or It may also contain materials in the vicinity.

[0217] For example, a transistor with high field-effect mobility as described above can be used to generate a gate signal. By using it in the driver, it is possible to provide a display device with a narrow bezel (also called a narrow bezel). Furthermore, transistors with high field-effect mobility are used as source drivers (especially source drivers). This is used in a demultiplexer connected to the output terminal of the shift register that the driver has. This makes it possible to provide a display device with a small number of wires connected to it.

[0218] Furthermore, even if the semiconductor layer 108 has a region where the atomic ratio of In is greater than the atomic ratio of M, If the crystallinity of semiconductor layer 108 is high, the field-effect mobility may be low. As for the crystallinity of 10⁸, for example, X-ray diffraction (XRD) The analysis is performed using an on (microscope), or a transmission electron microscope (TEM). The analysis can be performed using an on-electron microscope.

[0219] Here, impurities such as hydrogen or water mixed into the semiconductor layer 108 affect the transistor characteristics. This is problematic because it affects the semiconductor layer 108, hydrogen or water The fewer impurities such as ions, the better. Metal oxides with low impurity concentration and low defect level density are preferable. By using a film, it is possible to fabricate transistors with excellent electrical properties, which is preferable. By lowering the impurity concentration and the defect level density (reducing oxygen vacancies), the film can be modified. The carrier density can be reduced. Transistors using such metal oxide films as semiconductor layers A zista exhibits an electrical characteristic where the threshold voltage becomes negative (also known as normally-on). And there are few. Also, transistors using such metal oxide films have a significant off-current. Smaller characteristics can be obtained.

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

[0221] For example, a semiconductor layer 108 made by stacking two or more metal oxide films with different compositions can be used. Yes, it is possible. For example, when using In-M-Zn oxide, the number of atoms of In, M, and Zn 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 Among the films formed on a sputtering target with a ratio of 1:3:2, or in the vicinity thereof, It is preferable to use two or more stacked together.

[0222] Furthermore, a semiconductor layer 108 made by stacking two or more metal oxide films with different crystallinity properties can be used. Yes, it is possible. In that case, by using the same oxide target and changing the film deposition conditions, it is possible to create a film in the atmosphere. It is preferable that the material be formed continuously without touching it.

[0223] For example, the oxygen flow rate ratio during the formation of the first metal oxide film, which is formed earlier, is used for the second film, which is formed later. The oxygen flow rate ratio during deposition of the metal oxide film is made smaller than that of the first metal oxide film. During film formation, conditions are set so that no oxygen is flowed. This prevents acid from entering during the formation of the second metal oxide film. It can effectively supply the element. Also, the first metal oxide film is more efficient than the second metal oxide film. It is possible to create a film with low crystallinity and high electrical conductivity. On the other hand, the upper part By making the metal oxide film 2 a film with higher crystallinity than the first metal oxide film, semiconductor layer 1 This can suppress damage during the processing of 08 and during the deposition of the insulating layer 110.

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

[0225] This configuration provides a transistor 200 with excellent electrical characteristics and high reliability. This can be achieved.

[0226] The above is an explanation of Configuration Example 1.

[0227] [Configuration Example 2] The following describes a transistor configuration example that differs in some aspects from the above Configuration Example 1. Note that in the following, explanations may be omitted for parts that overlap with the above configuration example 1. In the drawing shown below, the parts having the same function as the above example configuration are hatched. Sometimes the same character is used, and no sign is added.

[0228] Figure 10(A) is a top view of transistor 200A, and Figure 10(B) is a transistor Figure 10(C) is a cross-sectional view of the 200A in the channel length direction, and the channel of transistor 200A This 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. Therefore, it differs mainly from the transistor 100 exemplified in Configuration Example 1. The conductive layer 107 is a semiconductor. It has a region that overlaps with layer 108 and conductive layer 112.

[0230] In transistor 200A, the conductive layer 107 is the first gate electrode (bottom gate electrode) The conductive layer 112 functions as a second gate electrode (also called a top gate electrode), and the conductive layer 112 is a second gate electrode (top gate electrode). It functions as a pole (also called a pole). In addition, a part of the insulating layer 103 is the first gate insulating layer In this manner, a portion of the insulating layer 110 functions as a second gate insulating layer.

[0231] The portion of the semiconductor layer 108 that overlaps with at least one of the conductive layer 112 and the conductive layer 107 , it functions as a channel formation region. For the sake of simplicity, the semiconductor layer 10 The portion that overlaps with the conductive layer 112 of 8 is sometimes called the channel-forming region, but in reality it is not conductive In the portion that is not superimposed on layer 112 but superimposed on conductive layer 107 (the portion including region 108n), A channel can be formed.

[0232] Furthermore, as shown in Figure 10(C), the conductive layer 107 consists of a metal oxide layer 114 and an insulating layer 11 0, and electrically connected to the conductive layer 112 through openings 142 provided in the insulating layer 103. This may be done. This will give the conductive layer 107 and the conductive layer 112 the same potential. It is possible.

[0233] The conductive layer 107 is made of the same material as conductive layer 112, conductive layer 120a, or conductive layer 120b. This can be used. In particular, if a material containing copper is used for the conductive layer 107, the wiring resistance can be reduced. It is preferable for this reason.

[0234] Furthermore, as shown in Figures 10(A) and (C), in the channel width direction, the conductive layer 11 It is preferable that 2 and the conductive layer 107 protrude outward beyond the edge of the semiconductor layer 108. At this time, as shown in Figure 10(C), the entire channel width direction of the semiconductor layer 108 is insulated. The structure is covered by a conductive layer 112 and a conductive layer 107 via an edge layer 110 and an insulating layer 103. .

[0235] With this configuration, the semiconductor layer 108 is protected from the electric field generated by the pair of gate electrodes. And it can be electrically surrounded. In particular, the conductive layer 107 and the conductive layer 112 are the same It is preferable to apply an electric potential. This induces a channel in the semiconductor layer 108. Because the electric field can be effectively applied, the on-current of the 200A transistor can be increased. Yes, it is possible. Therefore, it becomes possible to miniaturize the 200A transistor.

[0236] Furthermore, the conductive layer 112 and the conductive layer 107 may not be connected. In this case, one pair A constant potential is applied to one of the gate electrodes, and a signal to drive transistor 200A is applied to the other. You may also give it. In this case, the potential applied to one of the gate electrodes will affect transistor 200 The threshold voltage when driving A with the other gate electrode can also be controlled.

[0237] The above is an explanation of Configuration Example 2.

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

[0239] (Embodiment 3) In this embodiment, an electronic device according to one aspect of the present invention is shown in Figures 11(A), (B), and (C). This will be explained using the following: (A), (B), (C), (D), and (E).

[0240] The electronic device of this embodiment has a display device according to one aspect of the present invention in its display unit. Furthermore, the display unit of the electronic device can display high-quality images. Also, over a wide temperature range... It can display information with high reliability.

[0241] The display unit of the electronic device in this embodiment can display, for example, Full HD, 2K, 4K, 8K, It can display video with a resolution of 16K or higher. The screen sizes are: diagonal 20 inches or more, diagonal 30 inches or more, diagonal 50 inches or more, diagonal It can be 60 inches or larger, or 70 inches or larger diagonally.

[0242] Electronic devices that can use a display device according to one aspect of the present invention include, for example, televisions. Computer equipment, desktop or notebook personal computers, computer equipment Monitors such as digital signage, electronic billboards, etc. In addition to electronic devices with relatively large screens, such as large game machines like the Chinko machine, digital cameras Cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, Examples include portable information terminals and sound playback devices. Furthermore, a display device according to one aspect of the present invention is: Portable electronic devices, wearable electronic devices, VR (Virtual Reality) Suitable for real-time (AVR) devices, AR (Augmented Reality) devices, etc. It can be used.

[0243] An electronic device according to one aspect of the present invention may have a secondary battery and uses contactless power transmission. It is preferable that the secondary battery can be recharged.

[0244] Examples of secondary batteries include lithium polymer batteries (lithium-ion batteries) that use a gel-like electrolyte. Lithium-ion secondary batteries such as polymer batteries, nickel-metal hydride batteries, nickel-cadmium batteries, organic Examples include radical batteries, lead-acid batteries, air-based rechargeable batteries, nickel-zinc batteries, and silver-zinc batteries. ru.

[0245] An electronic device according to one aspect of the present invention may have an antenna. The antenna receives a signal. This allows the display unit to show images, information, etc. Also, the electronic device acts as an antenna. Furthermore, if a secondary battery is present, the antenna may be used for contactless power transmission.

[0246] An electronic device according to one aspect 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, electric current, voltage, power (including functions for measuring radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation) It is acceptable to have it.

[0247] An electronic device according to one aspect of the present invention can have various functions. For example, various information Functions to display (still images, videos, text images, etc.) on the display unit, touch panel function, calendar Functions to display the date or time, and to run various software (programs). Functions include: wireless communication, and reading programs or data recorded on a recording medium. It can have functions, etc.

[0248] Furthermore, in electronic devices having multiple display units, one display unit primarily displays image information. A function that displays one display unit and primarily displays text information on another display unit, or multiple display units It can have functions such as displaying three-dimensional images by displaying images that take parallax into account. Furthermore, in electronic devices having an image receiving unit, the function of taking still images or videos, Functions to automatically or manually correct shadowed images, and to record captured images on a recording medium (external or electronic). It can have functions such as saving to a built-in device and displaying captured images on the display unit. It is possible. However, the functions of an electronic device according to one aspect of the present invention are not limited to these, and various functions It can have.

[0249] Figure 11(A) shows the television device 1810. The television device 1810 is shown in the table. It includes an indicator unit 1811, a housing 1812, a speaker 1813, etc. Furthermore, it has an LED lamp and controls Operation key (including power switch or operation switch), connection terminals, various sensors, micro They may have phones, etc.

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

[0251] Television equipment 1810 can receive broadcast signals from terrestrial or satellite sources. Examples include radio waves that are transmitted. Also, broadcast radio waves include analog broadcasting and digital broadcasting. There are also broadcasts with video and audio, or audio only. For example, the UHF band (approximately 30 A specific frequency within the 0MHz to 3GHz or VHF band (30MHz to 300MHz) It can receive broadcast radio waves transmitted in multiple frequency bands. Also, for example, in multiple frequency bands By using multiple received data sets, the transfer rate can be increased, allowing for more information to be transmitted. This allows us to obtain information. This enables us to display video with a resolution exceeding Full HD. The display unit 1811 can show the resolution, for example, 4K, 8K, 16K, or higher. It is possible to display video with a resolution of [resolution].

[0252] Also, the internet, LAN (Local Area Network), and Wi-Fi It is transmitted via data transmission technologies over computer networks such as i(registered trademark). The system may also be configured to generate an image to be displayed on the display unit 1811 using the broadcast data. In this case, the television device 1810 does not need to have a tuner.

[0253] Figure 11(B) shows a digital signage 1820 mounted on a cylindrical column 1822. The digital signage 1820 has a display unit 1821.

[0254] The larger the display unit 1821, the more information can be provided at once. The wider the display area 1821, the more easily it catches people's attention, which can, for example, enhance the effectiveness of advertising. can.

[0255] By applying a touch panel to the display unit 1821, still images or videos can be displayed on the display unit 1821. In addition to displaying information, it is preferable that the user can operate it intuitively. Also, route information When used for purposes such as providing news or traffic information, intuitive operation is required. This can improve usability.

[0256] Figure 11(C) shows the notebook-type personal computer 1830. Computer 1830 consists of a display unit 1831, a casing 1832, a touchpad 1833, and a connection. It has ports such as 1834.

[0257] The Touchpad 1833 is a pointing device and input method such as a pen tablet. It functions and can be operated with a finger, stylus, etc.

[0258] Furthermore, the touchpad 1833 incorporates a display element. As shown in Figure 11(C)... By displaying input keys 1835 on the surface of the touchpad 1833, the touchpad 1833 can be used as a keyboard. When this happens, touch input key 1835. To achieve tactile feedback through vibration, a vibration module is incorporated into the touchpad 1833. If it's included.

[0259] Figures 12(A) and (B) show the personal information terminal 800. The personal information terminal 800 is housed in a housing. It has a body 801, a housing 802, a display unit 803, a display unit 804, and a hinge unit 805, etc.

[0260] The housing 801 and housing 802 are connected by a hinge portion 805. The portable information terminal 800 is As shown in Figure 12(A), the housing 801 is folded, and as shown in Figure 12(B) And you can open the casing 802.

[0261] For example, document information can be displayed on display units 803 and 804, and the ebook terminal It can also be used as a terminal. In addition, still images and videos can be displayed on the display units 803 and 804. It can also display images.

[0262] Thus, the portable information terminal 800 can be folded for portability, making it suitable for a wide range of uses. Excellent usability.

[0263] Furthermore, the enclosure 801 and enclosure 802 have a power button, operation buttons, an external connection port, and It may have a speaker, microphone, etc.

[0264] Figure 12(C) shows an example of a personal digital information terminal. The personal digital information terminal 810 shown in Figure 12(C) is , housing 811, display unit 812, operation buttons 813, external connection port 814, speaker 81 5. It has a microphone 816, a camera 817, etc.

[0265] The personal information terminal 810 is equipped with a touch sensor on the display unit 812. To make a phone call, or All operations, such as entering text, are performed by touching the display unit 812 with a finger or stylus. It can be done in this way.

[0266] Furthermore, the power can be turned ON or OFF by operating the operation button 813, and the display unit 812 will display an item. You can switch the type of image displayed. For example, from the email composition screen, you can switch to the main image. You can switch to a new screen.

[0267] Furthermore, the mobile information terminal 810 contains a detection device such as a gyro sensor or an accelerometer. By providing this, the orientation (vertical or horizontal) of the mobile information terminal 810 is determined, and the image of the display unit 812 is displayed accordingly. The orientation of the screen display can be automatically switched. To replace it, touch the display unit 812, operate the operation button 813, or use the microphone 816. This can also be done using voice input or other methods.

[0268] The personal information terminal 810 is one selected from, for example, a telephone, a notebook, or an information viewing device. Or it has multiple functions. Specifically, it can be used as a smartphone. The mobile information terminal 810 can, for example, make phone calls, send emails, view and create documents, play music, and move It can run various applications such as video playback, internet communication, and games. Cut.

[0269] Figure 12(D) shows an example of a camera. Camera 820 consists of a housing 821, a display unit 822, It has operation buttons 823, a shutter button 824, etc. The camera 820 also has a detachable... A capable 826 lens is attached.

[0270] Here, we'll refer to the camera 820 as the lens 826, which will be removed from the housing 821 and replaced. This configuration allows for the lens 826 and the housing 821 to be integrated.

[0271] Camera 820 takes still images or videos by pressing the shutter button 824. It can be displayed. Also, the display unit 822 has the function of a touch panel, and the display unit 8 It is also possible to take an image by touching button 22.

[0272] Note that the Camera 820 requires the attachment of a separate flash unit, viewfinder, etc. This is possible. Alternatively, these may be incorporated into the enclosure 821.

[0273] Figure 12(E) shows an example of a display device according to one aspect of the present invention mounted as an in-vehicle display. The display units 832 and 833 show navigation information, speedometer and tachometer. By displaying the meter, mileage, fuel gauge, gear status, air conditioning settings, etc., various Information can be provided. The display items and layout can be adjusted as needed according to the user's preferences. The output can be changed. A display device according to one aspect of the present invention can be used over a wide temperature range. This allows for reliable display in both low-temperature and high-temperature environments. Therefore, by using a display device according to one aspect of the present invention as an in-vehicle display, This can improve driving safety.

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

[0275] Figure 13(A) shows a perspective view of the display system, which consists of a display device 910 and a display screen. The display device 910 has an imaging device 911 positioned behind it. The opponent's image is displayed on surface 912. (See display system shown in Figures 13(A) and (B)) This is sometimes called a videophone device.

[0276] Since the display device 910 has the function of transmitting visible light, it is placed behind the display device 910. The imaging device 911 can be used to image the person interacting with the other person 913.

[0277] The interlocutor 913 is on the side of the first display surface 912, and the first is positioned so as to align with the other person's line of sight in the video. The display surface is visually inspected. Furthermore, in the imaging device 911, specifically the photographic lens 914, It is positioned so as to be in the line of sight of speaker 913. At this time, the imaging device 911 is positioned as to the interlocutor 9 Within the range of distances where imaging is possible, it is necessary to position the focus to match the interlocutor 913. be.

[0278] Figure 13(B) shows a top view of the videophone system, including the display device 910, the imaging device 911, The first display surface 912 is shown. When the interlocutor 913 faces the first display surface 912, Furthermore, in the image captured by the imaging device 911, the other interlocutor aligns their gaze with that of the interlocutor 913. It is possible.

[0279] Furthermore, this display system, while viewing the image displayed on the first display surface 912, Information from behind the display device 910 can be obtained. In the example shown in Figure 14(A), Speaker 913, while looking at the image displayed on the first display surface 912, behind the display device 910 The behavior of passersby 915 in the direction can be observed. Figure 14(B) is the same as Figure 14(A). A corresponding top view is shown. Note that the configuration shown in Figure 14(A) does not necessarily have an imaging device. As shown in Figures 14(A) and (B), this display system displays on the first display surface 912. An image can be obtained by combining the initial image with information about what lies behind it.

[0280] As described above, an electronic device can be obtained by applying a display device according to one aspect of the present invention. The application range of display devices is extremely broad, and they can be applied to electronic devices in all fields.

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

[0282] FPGA: 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: B Light unit, 31: substrate, 32: substrate, 33: light-emitting element, 34: diffuser 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: Capacity Quantitative element, 105: Capacitor element, 106: Liquid crystal element, 107: Conductive layer, 108: Semiconductor layer, 1 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: Transistor Zista, 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 Resistive region, 231b: semiconductor layer, 242: connector

Claims

[Claim 1] It comprises a transistor, a first conductive layer, a second conductive layer, and a third conductive layer. The transistor has multiple semiconductor layers, The number of the aforementioned 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-forming region is positioned between the first region and the second region when viewed from above. Each of the plurality of semiconductor layers has a channel-forming region containing a metal oxide. The aforementioned metal oxide comprises indium and zinc. Each of the plurality of semiconductor layers has a channel-forming region that overlaps with the first conductive layer. The first region overlaps with the second conductive layer and does not overlap with the first conductive layer. The second region overlaps with the third conductive layer and does not overlap with the first conductive layer. The third conductive layer has the function of transmitting visible light, The stacked second region and the third conductive layer are a display device having the function of transmitting visible light.

Images