Semiconductor equipment

Abstract

The objective is to provide a display device that provides accurate information. [Solution] The circuit is constructed using a transistor having an oxide semiconductor with a low off-current. In addition to the pixel circuit, a pre-charge circuit or test circuit is formed as part of the circuit. Because it uses semiconductors, the off-current is low, and therefore it is suitable for pre-charge circuits and test circuits. Therefore, the possibility of signal or voltage leakage causing display malfunctions is low. As a result, accurate A display device that can perform such a display can be provided.

Description

[Technical Field]

[0001] The present invention relates to semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, or methods for manufacturing the same. In particular, semiconductor devices having circuits composed of transistors using oxide semiconductor films, The present invention relates to display devices, liquid crystal display devices, light-emitting devices, or methods for manufacturing the same. [Background technology]

[0002] Conventionally, amorphous silicon was used as a switching element in display devices such as liquid crystal displays. Thin-film transistors (TFTs) that use a silicon layer formed by capacitors, etc., as the channel layer It is widely used. Thin-film transistors using amorphous silicon utilize field-effect transfer. Although the degree of precision is low, it has the advantage of being able to handle large-area glass substrates.

[0003] Furthermore, in recent years, transistors have been fabricated using metal oxides that exhibit semiconductor properties, and electronic devices The technology is attracting attention for its application in optical devices. For example, among metal oxides, tung oxide Stainless steel, tin oxide, indium oxide, and zinc oxide are known to exhibit semiconductor properties. Transitions using a transparent semiconductor layer composed of such metal oxides as the channel formation region The details are disclosed (Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2006-165532 [Overview of the project] [Problems that the invention aims to solve]

[0005] One aspect of the present invention aims to provide a semiconductor device with low noise, or One aspect of the present invention aims to provide a semiconductor device with high dielectric strength. One aspect of the present invention aims to provide a semiconductor device with low power consumption. Alternatively, one aspect of the present invention aims to provide a display device that performs correct display. Furthermore, the description of these problems does not preclude the existence of other problems. The embodiment does not need to solve all of the above-mentioned problems. [Means for solving the problem]

[0006] To solve the above problems, an oxide semiconductor (OS) is used. A circuit is constructed using transistors, particularly MOS transistors having oxide semiconductors. Therefore, the off-current is very low. low.

[0007] One embodiment of the present invention includes a pixel section containing a plurality of pixels and a pre-charge circuit, The precharge circuit has multiple first transistors, and each of the multiple pixels has a second It has a transistor and a liquid crystal element, and the first transistor and the second transistor are made of oxide A liquid crystal display device is provided, characterized by having a semiconductor.

[0008] Alternatively, one embodiment of the present invention comprises a pixel section including a plurality of pixels and an inspection circuit, The test circuit has multiple first transistors, and each of the multiple pixels has a second transistor The device has a transistor and a liquid crystal element, and the first transistor and the second transistor are made of oxide semiconductor A liquid crystal display device is provided, characterized by having the following features.

[0009] Alternatively, one aspect of an embodiment of the present invention has a pixel portion including a plurality of pixels and a circuit, and the circuit has a plurality of first transistors, and each of the plurality of pixels has a second transistor and a liquid crystal element. The gates of the plurality of first transistors are electrically connected to each other, and the plurality of first terminals of the first transistors are electrically connected to each other. All of the second terminals of the plurality of first transistors are electrically connected to the pixel portion. The gates of the plurality of first transistors are in a floating state, and the first transistor and the second transistor have an oxide semiconductor, and a liquid crystal display device is provided.

[0010] Alternatively, one aspect of an embodiment of the present invention has a pixel portion including a plurality of pixels and a circuit, and the circuit has a plurality of first transistors, and each of the plurality of pixels has a second transistor and a liquid crystal element. The gates of the plurality of first transistors are electrically connected to each other, and the plurality of first terminals of the first transistors are electrically connected to each other. All of the second terminals of the plurality of first transistors are electrically connected to the pixel portion. The first terminals of the plurality of first transistors are in a floating state, and the first transistor and the second transistor have an oxide semiconductor, and a liquid crystal display device is provided. [[ID=第30]]

[0011] In the above configuration, a liquid crystal display device is provided, wherein the oxide semiconductor had by the first transistor and the second transistor is a intrinsic semiconductor.

Advantages of the Invention

[0012] In the disclosed invention, by using a transistor having an oxide semiconductor with a low off-current, the This creates a circuit. Therefore, it prevents unwanted current from leaking into the circuit. Yes, it is possible. Therefore, the circuit is more likely to function correctly. For this reason, the transistors containing oxide semiconductors A display device having a circuit equipped with a converter can perform accurate display. [Brief explanation of the drawing]

[0013] [Figure 1] A circuit diagram illustrating a semiconductor device. [Figure 2] A circuit diagram illustrating a semiconductor device. [Figure 3] A circuit diagram illustrating a semiconductor device. [Figure 4] A circuit diagram illustrating a semiconductor device. [Figure 5] A circuit diagram illustrating a semiconductor device. [Figure 6] A timing chart illustrating the signal waveforms of semiconductor devices. [Figure 7] A timing chart illustrating the signal waveforms of semiconductor devices. [Figure 8] A circuit diagram illustrating a semiconductor device. [Figure 9] A circuit diagram illustrating a semiconductor device. [Figure 10] A circuit diagram illustrating a semiconductor device. [Figure 11] A circuit diagram illustrating a semiconductor device. [Figure 12] A cross-sectional view illustrating a semiconductor device. [Figure 13] Circuit diagrams and cross-sectional views illustrating the display device. [Figure 14] A cross-sectional view illustrating a display device. [Figure 15] A timing chart illustrating the waveforms of a display device. [Figure 16] A diagram illustrating electronic devices. [Figure 17] A diagram illustrating electronic devices. [Modes for carrying out the invention]

[0014] The embodiments will be described below with reference to the drawings. Similarly, symbols indicating the same thing are shown using common symbols across different drawings, and the same part or the same Detailed explanations of the parts with similar functions will be omitted.

[0015] (Embodiment 1) In this embodiment, a transistor having an oxide semiconductor, in particular, an oxide semiconductor in the active layer A device (semiconductor device, display device, or light-emitting device) configured using transistors. An example of this will be explained with reference to the drawing. The transistor having an oxide semiconductor is OFF Because the current is low, in semiconductor devices having oxide semiconductors, off-currents cause This can reduce the number of malfunctions. Alternatively, transistors having oxide semiconductors can reduce the number of malfunctions. It has a high voltage resistance. Therefore, it operates normally even when a high voltage is applied. This also allows for lower off-currents, thereby reducing malfunctions caused by off-currents. It is possible to do so.

[0016] Figure 1 shows an example configuration of the device shown in this embodiment. One aspect of this embodiment is the pixel section 1 It has 01 and circuit 111.

[0017] Multiple pixels are arranged in a matrix in the pixel section 101. Here, the pixels are arranged in a matrix Arranged in a row means that pixels are lined up in a straight line, either vertically or horizontally. This includes cases where they are arranged in a zigzag pattern or on a jagged line. For example, pixels 102a and 102b are arranged side by side horizontally. Similarly, Pixels 102c and 102d are arranged side by side in the horizontal direction. Furthermore, pixel 10 Pixels 2a and 102c are arranged vertically. Similarly, pixels 102b and Each pixel 102d is arranged vertically. And each pixel is connected by wiring. And they are connected to each other. Pixels arranged vertically are connected by wiring that extends vertically. The connected pixels, arranged horizontally, are linked by wiring that extends horizontally. For example, pixels 102a and 102b are connected by wiring 104a. Similarly, pixels 102c and 102d are connected by wiring 104b. Pixels 102a and 102c are connected by wiring 103a. Pixels 102b and 102d are connected by wiring 103b. Furthermore, if there is another wiring, for example, wiring that connects all pixels (common wiring, power lines, etc.), Therefore, it is possible to connect pixels. The same applies to other pixels as well. It is located and connected in the same way.

[0018] Here, wirings that extend in the left-right direction, such as wiring 104a and wiring 104b, are each It may be connected to the gate of the transistor that the pixel has. Therefore, wiring 104a Wirings that extend in the left-right direction, such as wiring 104b, are gate signal lines (gate wiring It can have the function of a wire, gate wire, etc. Alternatively, wiring 104a, wiring 104b As shown, the wiring arranged in a left-right direction is supplied with a signal to be selected one row at a time, and The signals may be scanned. Therefore, the wiring 104a and wiring 104b The wiring extending horizontally is the scan signal line (scan wiring, scan line). It can have functions such as...

[0019] Alternatively, wiring 103a, wiring 103b, wiring 103c, wiring 103d, wiring 103e, Wire 103f, Wire 103g, Wire 103h, Wire 103i, Wire 103j, Wire 103k , such as wiring 103L (wiring 103a to wiring 103L), are arranged extending in the vertical direction. The wiring may be connected to the source or drain of the transistors that each pixel possesses. Therefore, wirings 103a to 103L, which are arranged to extend in the vertical direction A line can function as a source signal line (source wiring, source line, etc.). For wiring that extends vertically, such as wiring 103a to wiring 103L, data Signals such as video signals and source signals may be supplied. Therefore, wiring 103 Wirings that extend vertically, such as a or wiring 103L, are data signal lines. It can have functions such as wiring and data lines.

[0020] Next, the circuit 111 is arranged to extend vertically, as shown by wiring 103a to wiring 103L. The pixel unit 101 or each individual pixel is connected via the wiring. Circuit 111 is It can be configured as a circuit with various functions.

[0021] Figure 2 shows an example of the circuit configuration that illustrates the details of circuit 111. Circuit 111 is an example and Therefore, it is possible to have the function of a pre-charge circuit, or the function of a test circuit. It is possible to have. Alternatively, circuit 111 has the function of a pre-charge circuit and a test circuit. It is possible to have both functions. However, one embodiment of the present invention is this It is not limited to this.

[0022] Circuit 111 consists of transistors 201a, 201b, and 201c. Transistor 201d, Transistor 201e, Transistor 201f, Transistor 2 01g, Transistor 201h, Transistor 201i, Transistor 201j, Transistor Zistor 201k, Transistor 201L (Transistor 201a to Transistor 201) It has L). Wiring 103a to 103L is connected to wiring 202 and transistor 20 They are connected via transistors 1a through 201L. Therefore, the transistors Either the source or drain of transistor 201a to transistor 201L is connected to wiring 202. And each of the source or drain of transistors 201a to 201L These are connected to wiring 103a to wiring 103L, respectively. And wiring 203 It is connected to the gate of transistor 201a to transistor 201L. The gates of transistors 201a through 201L are connected to each other. ru.

[0023] In this specification, the term "transistor" includes the gate, drain, and source. It is an element having at least three terminals. And, drain (drain terminal, drain Between the drain region (or drain electrode) and the source (source terminal, source region, or source electrode) It has a channel region, and current flows through the drain, the channel region and the source. It is possible to do that.

[0024] In this specification, an example of a transistor is a transistor with two or more gate electrodes. A multi-gate transistor can be used. Because the Nell regions are connected in series, the structure consists of multiple transistors connected in series. Therefore, the multi-gate structure reduces off-current and improves the transistor's breakdown voltage (reliability). (Improvement) can be achieved. Alternatively, a multi-gate structure can be used when operating in the saturation region. Even if the voltage between the drain and source changes, the current between the drain and source does not change much. A voltage-current characteristic with no change and a flat slope can be obtained. By utilizing certain voltage-current characteristics, an ideal current source circuit or a function with very high resistance values ​​can be created. A dynamic load can be realized. As a result, a differential circuit or current mirror circuit with good characteristics can be achieved. This can be achieved.

[0025] As an example of a transistor, there is a configuration in which gate electrodes are arranged above and below the channel. A transistor of this type can be applied. The gate electrodes are arranged above and below the channel. By doing so, the circuit configuration becomes one in which multiple transistors are connected in parallel. This increases the channel area, allowing for an increase in the current value. Alternatively, the channel By arranging gate electrodes above and below, a depletion layer is more likely to form. Therefore, it is possible to improve the subthreshold swing value (S value).

[0026] Note that the circuit configuration of circuit 111 is not limited to the circuit configuration shown in Figure 2, and various circuit configurations can be adopted. This is possible. An example of the circuit 111 in that case is shown in Figure 3. Therefore, Figures 1 and 2 The points discussed can also be applied to Figure 3.

[0027] Figure 3 shows an example of providing multiple wirings 202 as in Figure 2. Note that in Figure 3, the wiring Although the case with three 202 units has been shown, the embodiments of the present invention are not limited thereto. It is possible to have two or four or more wires. Wiring 103a to wiring 103L are One of the following wires 202a, 202b, or 202c, and transistor 201 a to transistor 201L are connected, respectively. Therefore, the transistors Either the source or drain of transistor 201a to transistor 201L is connected to wiring 202a, wiring Connected to either 202b or wiring 202c, transistor 201a or... Each of the source or drain of the inverter 201L is connected to the wiring 103a or the other. It is connected to wire 103L. And wire 203 is connected to transistor 201a or to transistor It is connected to the gate of transistor 201L. Therefore, transistor 201a to transistor 201L is connected. The gates of the 201L are connected to each other.

[0028] When displaying in color, each color of the pixel to be displayed, and wiring 202a, wiring 202b, Or, regarding wiring 202c, each color and wiring 202a, wiring 202b, or wiring 202 It is possible to associate it with any one of c. For example, if the wiring 202a has a transistor The wiring connected via the terminal is connected to the red pixel. Therefore, wiring 202a These are connected via transistors to wiring 103a, wiring 103d, wiring 103g, and wiring 10 It is connected to 3j. Similarly, the wire connected to wire 202b via the transistor is , connected to the blue pixels. Therefore, each wire 202b is connected via a transistor It is connected to wiring 103b, wiring 103e, wiring 103h, and wiring 103k. The wiring connected to wiring 202c via a transistor is connected to the green pixel. Therefore, wiring 202c is connected to wiring 103c and wiring 10 via transistors, respectively. It is connected to 3f, wiring 103i, and wiring 103L. Note that the colors are not limited to red, blue, and green. For example, you could add white to make it four colors, or use several slightly different shades of red (or blue or green). It is also possible to use it. This allows for color control.

[0029] Next, another example of the circuit configuration of circuit 111 is shown in Figure 4. Therefore, Figures 1, 2 and 3 The points discussed can also be applied to Figure 4.

[0030] Figure 4 shows an example of providing multiple wirings 203 as in Figure 2. Note that in Figure 4, the wiring Although the case with three 203 units has been shown, the embodiments of the present invention are not limited thereto. It is possible to have two or four or more wires. Wiring 103a to wiring 103L are Wiring 202 is connected via transistors 201a to 201L, respectively. Therefore, the source or drain of transistors 201a to 201L One end of the input is connected to wiring 202 and transistors 201a to 201L. Each of the source and drain ends is connected to wiring 103a to 103L, respectively. And, one of the following: wiring 203a, wiring 203b, or wiring 203c It is connected to the gate of transistor 201a to transistor 201L. That is, some of the transistors 201a to 201L (for example, transistor For sta201a, 201d, 201g, and 201j, the gates are connected to each other. , connected to wiring 203a. Similarly, transistors 201a to 20 Another part of 1L (for example, transistors 201b, 201e, 201h, 201k) Regarding the gates, they are connected to each other and connected to wiring 203b. Similarly, Another part of transistor 201a to transistor 201L (for example, For ZISTA 201c, 201f, 201i, and 201L, the gates are connected to each other. It is connected to wiring 203c.

[0031] When displaying in color, each color of the pixel to be displayed, and wiring 203a, wiring 203b, Or, regarding wiring 203c, each color and wiring 203a, wiring 203b, or wiring 203 It is possible to associate it with any one of c. For example, wiring 203a and gate are connected The wiring connected to wiring 202 via the connected transistor is connected to the red pixel. Therefore, wiring 202 is connected to each gate of wiring 203a. Connected to wires 103a, 103d, 103g, and 103j via a transistor. Similarly, wiring is done through the transistor to which wiring 203b and the gate are connected. The wiring connected to 202 is connected to the blue pixel. Therefore, wiring 202 is Wiring 203b and the gate are connected to each transistor via wiring 103b, It is connected to wire 103e, wire 103h, and wire 103k. Similarly, it is connected to wire 203c and The wiring connected to wiring 202 via the transistor to which the ret is connected is the green pixel. It is connected to [the gate]. Therefore, wire 202 is connected to wire 203c. Through each transistor, wiring 103c, wiring 103f, wiring 103i, wiring 103 It is connected to L. Note that the colors are not limited to red, blue, and green; for example, white can be added to make it four colors. It is also possible to use multiple slightly different shades of red (or blue or green). Therefore, it is possible to control the color.

[0032] Next, another example of the circuit configuration of circuit 111 is shown in Figure 5. Therefore, Figures 1, 2, 3, The points made regarding Figure 4 can also be applied to Figure 5.

[0033] Figure 5 shows an example of providing multiple instances of wiring 202 and wiring 203 as shown in Figure 2. Therefore, Figure 5 shows the case where there are multiple wirings 203 in Figure 3, or the wiring in Figure 4. This also applies to cases where multiple lines 202 are provided. Note that in Figure 5, wiring 202 and wiring 203 Although the cases of three units each have been shown, one embodiment of the present invention is not limited thereto. It is possible to have two or more wires. Wiring 103a to wiring 103L are , one of the following: wiring 202a, wiring 202b, or wiring 202c, and transistor 2 They are connected via transistors 01a through 201L. Therefore, Either the source or drain of transistor 201a or transistor 201L is connected to wiring 202a. Connected to either wire 202b or wire 202c, transistor 201a The source or drain of transistor 201L is connected to the other end of wiring 103, respectively. It is connected to wiring a to wiring 103L. And wiring 203a, wiring 203b, or wiring One of the lines 203c is the gate of transistor 201a through transistor 201L. It is connected to the above. Therefore, among transistors 201a to 201L For some of them (for example, transistors 201a, 201d, 201g, 201j), The gates are connected to each other and connected to wiring 203a. Similarly, transistor 20 Another part of transistor 1a to transistor 201L (for example, transistor 201b, 20 For 1e, 201h, and 201k, the gates are connected to each other and connected to wiring 203b. It continues. Similarly, among transistors 201a to 201L, further For other parts (e.g., transistors 201c, 201f, 201i, 201L): The gates are connected to each other and connected to wiring 203c.

[0034] Furthermore, when displaying in color, the same as in Figures 2 to 4, each color of the pixel to be displayed and the wiring 20 3a, wiring 203b, or wiring 203c or wiring 202a, wiring 202b, or wiring Regarding 202c, each color and wiring 203a, wiring 203b, or wiring 203c To match any one of them, or wiring 202a, wiring 202b, or wiring 202c It is possible to associate it with any one of them. This allows for color control. ru.

[0035] (Embodiment 2) In this embodiment, an example of the operation of the circuit 111 described in Figures 2 to 5 will be described.

[0036] Circuit 111 can have various functions depending on the operating method. For example, The circuit 111 may have the function of a test circuit and / or a pre-charge circuit. However, However, one embodiment of the present invention is not limited thereto and may have other functions. That is the case.

[0037] First, we will describe how circuit 111 operates when it is used as a pre-charge circuit. The waveform when precharging is performed is shown in Figure 6. In a certain row of wiring, for example wiring 104a The supplied signal waveform is shown in Figure 6(A). Signal 901 is a waveform with a period of 902. A period of 902 corresponds, for example, to one frame period or one subframe period. There are many matches. Signal 901 is an H signal only during period 903 within period 902. During other periods, the signal is L. Period 903 is, for example, 1 gate This often corresponds to a selection period or a 1H period. Figure 6(B) shows the 1-gate selection period in detail. The waveform shown is for the case indicated. The gate selection period is the first half period 904 and the second half period 905. It is possible to consider this in two parts. In the first part, period 904, a predetermined voltage is distributed in advance. It can be supplied to line 103a to wiring 103L. In this way, a predetermined voltage can be supplied in advance. The supplying action corresponds to pre-charging. Therefore, the first half of period 904 is pre-charging. It can also be said that this is a period. In the latter half of the period 905, the video signal is supplied. Therefore, it is also possible to say that the latter period 905 is the signal input period. Signal 908 is supplied, for example, to one of the wirings 103a through 103L. The signal is shown. Signal 908 is approximately equal to potential 906 during the first period 904. This becomes an electric potential. Here, it is possible to say that the electric potential 906 is the reference electric potential, and as an example, Therefore, the voltage supplied to the display element, for example, the liquid crystal element, is approximately equal to the common potential or opposing potential. It is possible for it to be at a certain position, or at a potential that is approximately midway between the amplitudes of the video signal's potential. This is desirable. Then, in the latter half of period 905, signal 908 has a potential corresponding to the video signal. Therefore, the potential of signal 908 in the latter half of period 905 is the video signal or The value will vary depending on the polarity of the signal supplied to the liquid crystal element. Thus, By supplying a constant voltage to wiring 103a to wiring 103L, the signal can be supplied quickly. This makes it possible to perform the task more quickly. Therefore, the signal writing speed becomes faster, and the signal writing time is reduced. This will shorten the time required.

[0038] In the circuit shown in Figure 2, a signal like signal 907 is supplied to wiring 203. Signal 907 is During the first half of the period 904, transistors 201a through 201L were in a conductive state. The voltage is set to turn on. And the potential 906 is supplied to wiring 202. As a result, in the first half of period 904, wiring 103a to wiring 103L were pre-charged. It is possible to perform the action.

[0039] At this time, a transistor having an oxide semiconductor is used to control the potential of each wire. This reduces the effects of the transistor's off-current, thereby reducing voltage and noise leakage. This allows for the supply of accurate voltage to the wiring. Therefore, it has an oxide semiconductor. By using transistors, accurate display is possible.

[0040] Thus, transistors 201a through 201L are controlled by the gate signal. It has a function to control the on and off. Therefore, transistor 201a to transistor The STA201L can have a switch function.

[0041] In the case of the circuit in Figure 3, there are multiple wires, such as wires 202a to 202c. Therefore, in the first half of period 904, different wirings 103a to 103L are used. It becomes possible to supply an electric potential. Therefore, for example, in the first period 904, color Depending on the situation, it becomes possible to supply different potentials to wiring 103a to wiring 103L. Therefore, it can perform optimal actions to represent a variety of colors.

[0042] Alternatively, in the case of the circuit in Figure 4, there are multiple wires such as wires 203a to 203c. Therefore, by further dividing the first half of the period 904 into multiple periods, Turn on only one of either transistor 201a or transistor 201L to make it conductive. This makes it possible to do so. In this case, the signal waveform supplied to wiring 203a to wiring 203c This is shown in Figure 7. Signal 907a indicates the signal supplied to wiring 203a, and signal 907b indicates the distribution The signal supplied to line 203b is shown, and signal 907c is shown as the signal supplied to wiring 203c. Signal 907a is an H signal only during the first half of the first half of period 904. Signal 907b is an H signal only during the middle period of the first half of period 904. Signal 907c is the previous The signal becomes H only during the latter half of the half-period 904. In this way, the first half of the period 904 is Furthermore, by dividing it into multiple periods, in each of the multiple periods, wiring 202 By supplying different potentials to the wiring 103a to 103L, It is possible to make the potentials different. Therefore, in the first half of period 904, the color Accordingly, it becomes possible to supply different potentials to wiring 103a to wiring 103L, respectively. Therefore, it can perform the optimal action according to the color.

[0043] Alternatively, in the case of the circuit in Figure 5, there are multiple wires such as wires 202a to 202c. Therefore, in the first half of period 904, different wirings 103a to 103L are used. It becomes possible to supply potential. Furthermore, multiple wirings such as wiring 203a to wiring 203c It has the following wiring. Therefore, the first half of period 904 is divided into multiple periods, as shown in Figure 7. By doing so, only one of transistors 201a through 201L will be affected. It becomes possible to make it conductive (turn on). In this way, the first half of period 904, Furthermore, by dividing it into multiple periods, in each of the multiple periods, wiring 202 By making the potential supplied to wiring a to wiring 202c different, wiring 103a to wiring The potential supplied to line 103L can be made different. Therefore, the first half of period 9 In 04, different potentials are supplied to wiring 103a to wiring 103L according to their respective colors. This makes it possible to perform the optimal action according to the color.

[0044] Next, we will describe how to operate circuit 111 when it is used as a test circuit. First, Figure Let's discuss case 2.

[0045] First, a signal is supplied to the pixel by some means. For example, wiring 103a to wiring 1 A signal is supplied from the signal line drive circuit connected to 03L to wiring 103a through 103L. More preferably, the signal is supplied to one of the wirings 103a to 103L. Alternatively, turn on transistors 201a to 201L and connect them via wiring 202. And, more preferably, wiring 103a to wiring 103L A signal is supplied to one of them. Or, more preferably, to wiring 103a to wiring 103L. Alternatively, a needle for supplying a signal may be brought into contact with one of the wires 103a to 103L. This supplies the signal. Then, the gate wires such as wiring 104a or wiring 104b A high signal is supplied to one of the pixels. Then, if the transistor within the pixel is operating normally... In this case, a signal is supplied to the pixel. Then, an L signal is supplied to its gate line. As a result, The signal is held within the pixel.

[0046] Next, an H signal is supplied to that gate line. Then, the signal held within the pixel is routed. It is supplied to wiring 103a to 103L. At that time, an H signal is supplied to wiring 203, The transistor 201a or transistor 201L is made conductive. As a result, within the pixel The signal that was being held can be read out via wiring 202.

[0047] At this time, if there is a defect in the transistor within the pixel, the signal cannot be read out properly. Therefore, it is possible to check whether the transistor is functioning correctly based on its quality. .

[0048] And if a signal was being supplied to one of the wires 103a through 103L, then another A signal is supplied to one gate, and the same operation is repeated. Furthermore, this operation is extended to all gate lines. This is done. This allows all pixels to be inspected. Note that one gate line is selected. In this situation, of the multiple pixels connected to that gate line, only one pixel By supplying and reading signals, it is possible to inspect each pixel accurately. Or, to supply and read signals to some or all of the pixels among multiple pixels. This allows for a more general inspection of individual pixels.

[0049] In the case of Figure 3, multiple wires such as wires 202a to 202c are arranged. Therefore, the signals held within multiple pixels are routed through wiring 202a to wiring 202c. Through this, data can be read simultaneously. Therefore, in the case of Figure 3, three wires are arranged. Therefore, when supplying a signal to a pixel for the first time, a signal is supplied to three pixels simultaneously, and the reading When displaying an image, it is possible to read three pixels simultaneously. Therefore, inspection can be performed quickly. This allows for a shorter manufacturing time for semiconductor devices and other components, thereby reducing costs. It can be reduced.

[0050] In the case of Figure 4, multiple wires such as wires 203a to 203c are arranged. Therefore, when reading out the signal held within the pixel via wiring 202, By sequentially changing the signals supplied to wiring 203a to wiring 203c to H signals, The signal can be read out. Therefore, when supplying a signal to a pixel for the first time, simultaneously When supplying signals to multiple pixels and reading them out, it is possible to read them out sequentially, one pixel at a time. Therefore, inspections can be performed quickly. This allows for a shorter development period and reduced costs.

[0051] In the case of Figure 5, multiple wires such as wires 202a to 202c are arranged. Therefore, the signals held within multiple pixels are routed through wiring 202a to wiring 202c. It can be read simultaneously via wiring 203a to wiring 203c. Multiple wires are arranged. Therefore, the signal held within the pixel is routed through wire 202. When reading via this, the signals supplied to wiring 203a to wiring 203c are sequentially H signals. By doing so, the signals can be read out sequentially. Therefore, the inspection can be done quickly. This can be done. Therefore, the manufacturing process time for semiconductor devices and the like can be shortened. This can reduce costs.

[0052] Such inspections are carried out as part of the manufacturing process for semiconductor equipment and other devices. Once semiconductor devices are assembled and shipped, the test circuits will not be operated. .

[0053] Furthermore, if the off-current of transistors 201a to 201L is large, the current This causes leakage. As a result, noise enters wiring 103a to wiring 103L. Here, transistors having an oxide semiconductor are defined as transistor 201a to transistor 2 By using it as 01L, the off-current can be reduced, and noise can be reduced. .

[0054] In this way, circuit 111 can realize various functions by changing its operating method. It is possible. Therefore, circuit 111 functions as a pre-charge circuit and a test circuit. It is also possible to have both functions. By having both functions, multiple functions can be achieved with fewer circuits. Because it can implement various functions, it is possible to achieve lower costs and lower power consumption.

[0055] (Embodiment 3) In this embodiment, an example of the circuitry surrounding circuit 111 will be described.

[0056] Figure 8 shows an example of circuit 111, pixel section 101, and the surrounding circuits. (Substrate 51) On 1, the circuit 111 and the pixel unit 101 are arranged. Therefore, the circuit 111 is The transistors and wiring are the same as the transistors and wiring of the pixel unit 101, and simultaneously It is deposited on, etched at the same time, and a pattern is formed at the same time. In other words, circuit 1 11 and the pixel portion 101 are formed simultaneously through the same process and on the same substrate. Therefore, the materials of the transistor and wiring are such that the circuit 111 and the pixel section 1 01 is the same. Therefore, the transistor of the pixel part 101 has an oxide semiconductor. If present, then the transistor in circuit 111 also has an oxide semiconductor.

[0057] Furthermore, in this specification, transistors can be formed using various substrates. The type of substrate is not limited to a specific one. One example of such a substrate is a semiconductor substrate. Solid substrates (e.g., single crystal substrates or silicon substrates), SOI substrates, glass substrates, quartz substrates, Examples include flexible substrates. One example of a flexible substrate is polyethylene terephthalate (PET). ), plastics such as polyethylene naphthalate (PEN), or acrylic, etc. Examples include flexible synthetic resins.

[0058] Furthermore, a transistor is formed using one substrate, and then the transistor is transferred to another substrate. Alternatively, the transistors may be placed on a separate substrate.

[0059] Furthermore, all the circuits necessary to achieve the specified function are formed on the same circuit board. This is possible. In this way, cost reduction is achieved by reducing the number of parts, or the connection points with circuit components. Reliability can be improved by reducing the number of occurrences.

[0060] In Figure 8(A), circuits 501, 502, 503, and 504 are located on substrate 51. It is located on a different circuit board from 1. Therefore, as an example, circuits 501 and 502 Circuit 503 or Circuit 504 is an IC chip using a single crystal substrate or SOI substrate. It is configured to have the following: However, circuit 501, circuit 502, circuit 503, and / or The path 504 is provided on the substrate 511 using COG (chip-on-glass) mounting. There are cases where this occurs.

[0061] Here, circuit 501 controls circuit 111, supplies signals and voltages to circuit 111, or, It has the function of reading signals from circuit 111. Circuit 501 is connected to circuit 11 Depending on the function that 1 has, it has a corresponding function. For example, circuit 111 is pre If it has the function of a charge circuit, the circuit 501 has the function of controlling the pre-charge operation. It has. Similarly, if circuit 111 has the function of a test circuit, then circuit 501 has the function of a test circuit. It has a function to control the operation of the inspection. Similarly, circuit 111 is a pre-charge circuit and inspection If the circuit has a function, the circuit 501 has the function of controlling the pre-charge and inspection operations. It has.

[0062] Circuit 502 has the function of supplying signals to wiring 104a, wiring 104b, etc. Therefore, circuit 502 has the function of a gate line drive circuit (scan driver). Circuit 503 has the function of supplying signals to wiring 103a to wiring 103L. Therefore, circuit 503 functions as a signal line drive circuit (data driver). Circuit 504 may have the function of controlling circuit 502 or circuit 503. It has a controller, a pulse generation circuit, and a clock signal. Common voltage generation circuit, common voltage generation circuit, timing generator circuit, image processing circuit, or It can have functions such as a power supply circuit.

[0063] Figure 8(B) corresponds to the case where the configuration in Figure 8(A) does not include circuit 501. Circuit 111 If it functions as a test circuit, then circuit 501 is required when the test is being performed. However, after the inspection is complete, circuit 501 is no longer needed. Therefore, during the inspection, Figure 8(A) As shown in the diagram, circuit 501 is provided, and after the inspection is complete, circuit 501 can be removed. If circuit 501 is removed as in 8(B), wiring 202 and wiring 203 flow It enters a tingling state.

[0064] In Figure 8, circuits 501, 502, 503, and 504 are located on substrate 51. Although it was provided on a different substrate than 1, one embodiment of the present invention is not limited thereto. For example, some of these circuits can be provided on the circuit board 511. Figure 9 shows an example where circuit 502 is provided on substrate 511. Figure 9(A) Figure 9(B) shows a configuration having circuit 501, similar to Figure 8(A), and Figure 9(B) is the same as Figure 8(B). The diagram shows a configuration without circuit 501. Therefore, in Figure 9, the circuit 111 and the pixel section 10 Circuit 1 and circuit 502 are formed on the same substrate through the same process. Therefore, If the transistor of the pixel section 101 has an oxide semiconductor, the transistor of the circuit 111 The transistors in the STA and circuit 502 also contain oxide semiconductors. Figure 9(B If circuit 501 is removed as shown above, wiring 202 and wiring 203 will float It enters a state of being 'g'.

[0065] In this way, by forming the circuit 502 on the same substrate as the pixel section 101, the cost can be reduced. It can be made easier.

[0066] As an example of a different case from Figure 9, circuit 503 or a part of circuit 503 is also on board 511. It is also possible to provide it. An example of a part of the circuit 503 is wiring 103a to It is possible to connect an analog switch (transfer gate) to line 103L. Similarly, circuit 504 or a part of circuit 504 can also be provided on the substrate 511.

[0067] (Embodiment 4) This embodiment shows an example of the pixels that the pixel unit 101 has.

[0068] Figure 10(A) shows an example of the circuit of pixel 102a. A transistor 80 is connected to wiring 104a. The gate of transistor 801 is connected. The first terminal of transistor 801 is connected to wire 103a. The second terminal of transistor 801 is connected to the first terminal of display element 802. The second terminal of the indicator element 802 is connected to the wiring 803. The first terminal of the capacitive element 804 is The second terminal of transistor 801 is connected to the second terminal of capacitive element 804, and the second terminal of capacitive element 804 is connected to wiring 805. It is connected to this.

[0069] Here, the wiring 803 can be connected to each other at all pixels. And the specified voltage is supplied. Therefore, wiring 803 is a common wire. It can also have functions such as a counter electrode.

[0070] Here, wiring 805 is connected to other pixels, for example, left and right pixels. This is possible. And a predetermined voltage is supplied. Therefore, wiring 805 is common. It can have functions such as wiring and capacity wiring.

[0071] Furthermore, transistor 801 supplies a signal to display element 802 or capacitive element 804. It is possible to have a function to select whether or not. Therefore, transistor 801, It can have a switching function. Alternatively, transistor 801 is a switching transistor. A transistor (switching transistor) can function as a selection transistor. It is possible.

[0072] It is also possible to omit the capacitive element 804 and improve the aperture ratio. The circuit diagram for that case is shown below. This is shown in Figure 10(B). Transistor 801 is a transistor with a low off-current, for example However, by using a transistor having an oxide semiconductor, even if the capacitive element 804 is omitted This allows the voltage applied to the display element 802 to be maintained.

[0073] Note that the examples of pixel circuits are not limited to the circuit in Figure 10. Figure 11(A) shows another example of a pixel circuit. Here is an example. The gate of transistor 1301 is connected to wiring 104a. The first terminal of transistor 1301 is connected to wiring 103a, and the second terminal of transistor 1301 is connected to wiring 103a. This is connected to the gate of transistor 1311. The first terminal of transistor 1311. It is connected to wiring 1305, and the second terminal of transistor 1311 is connected to the first terminal of display element 802. It is connected to terminal 1. The second terminal of the display element 802 is connected to wiring 1303. The first terminal of the capacitive element 1304 is connected to the second terminal of the transistor 1301, and the capacitive element The second terminal of child 1304 is connected to the second terminal of transistor 1311.

[0074] Note that the wiring or terminal to which the second terminal of the capacitive element 1304 is connected is limited to that shown in Figure 11(A). It is not connected to another wire, for example, wire 1305.

[0075] Here, the wiring 1303 can be connected to each other at all pixels. And a predetermined voltage is supplied. Therefore, wiring 1303 is a common wiring, opposite electrode. It can also function as a cathode wire or cathode wire.

[0076] Here, the wiring 1305 is connected to other pixels, for example, the left and right pixels or the top and bottom pixels. It is possible to connect to it. And a predetermined voltage is supplied. Therefore, Wiring 1305 has functions such as common wiring, capacitance wiring, power lines, current supply lines, and anode lines. It is possible to do so.

[0077] Furthermore, transistor 1301 sends a signal to transistor 1311 or capacitive element 1304. It is possible to have a function to select whether or not to supply. Therefore, transistor 1301 can have a switching function. Alternatively, transistor 1301 can have a switching function. It can function as a switching transistor or a selection transistor.

[0078] Transistor 1311 supplies signals, voltage, or current to the display element 802. It has a switch function to select whether or not to do so, and a function as a current source to control their magnitude. It is possible to do so. Alternatively, transistor 1311 can be used as a drive transistor. It is possible to have that function.

[0079] It is also possible to omit the capacitive element 1304 and improve the aperture ratio. The circuit in that case is shown below. The diagram is shown in Figure 11(B). Transistors 1301 and 1311 are defined as transistors with low off-current. By using a transistor, for example, a transistor having an oxide semiconductor, a capacitive element 1 Even if 304 is omitted, the voltage applied to the display element 802 can be maintained.

[0080] Furthermore, the display element 802 can be replaced with various elements, and can function as a light-emitting element. It is also possible to enable this function. Circuit diagram when light-emitting element 802a is applied as the display element. This is shown in Figure 11(B).

[0081] As an example of a display element, an EL (electroluminescent) element (organic material and EL elements containing inorganic materials, organic EL elements, inorganic EL elements), LEDs (white LEDs, red LEDs) D, green LED, blue LED, etc.), liquid crystal elements, electronic ink, electrophoretic elements, carbon In tubes, etc., the contrast, brightness, reflectance, transmittance, etc. are affected by electromagnetic effects. Some have a display medium that changes. An example of a display device using liquid crystal elements is a liquid crystal display. Examples include displays. An example of a display device using electronic ink or electrophoretic elements is... Examples include electronic paper.

[0082] An example of an EL element is an anode, a cathode, and an EL layer sandwiched between the anode and cathode. Some elements possess this technology. One example of an EL layer is the use of light emission (fluorescence) from singlet excitons. This method utilizes the emission (phosphorescence) from triplet excitons, and the emission from singlet excitons. This includes methods that utilize fluorescence and methods that utilize light emission (phosphorescence) from triplet excitons. Things formed by organic matter, things formed by inorganic matter, things formed by organic matter Includes materials formed from inorganic substances, includes polymer materials, low-molecular-weight materials. These include those containing the same material, or those containing both high-molecular-weight and low-molecular-weight materials. Furthermore, it is not limited to this, and various materials can be used as EL elements.

[0083] One example of a liquid crystal element is one in which the transmission or non-transmission of light is controlled by the optical modulation effect of the liquid crystal. There is such an element. This element can be constructed from a pair of electrodes and a liquid crystal layer. 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 diagonal electric field). It is controlled by (including the electric field in the direction). Furthermore, as a method of driving liquid crystals, TN (Twist) (ed Nematic) mode, STN (Super Twisted Nematic) ) mode, IPS (In-Plane-Switching) mode, FFS (Frin (Field Switching) mode, MVA (Multi-domain) Vertical Alignment) mode, PVA(Patterned Ver. tical Alignment) mode, ASV (Advanced Super V) iew) mode, ASM(Axially Symmetric aligned Mi cro-cell) mode, OCB (Optically Compensated B irefringence) mode, ECB (Electrically Controlled) (Limited Birefringence) mode, FLC (Ferroelectric) Liquid Crystal mode, AFLC (AntiFerroelectr IC Liquid Crystal (PDLC) mode, PDLC (Polymer Dispense) (Responsible Liquid Crystal) mode, PNLC (Polymer Net) Work Liquid Crystal) mode, guest host mode, blue phase (B There are modes such as lune phase. However, this is not limited to liquid crystal elements and their Various drive systems can be used.

[0084] The transistors in circuit 111 have fewer constraints on their layout. Therefore, the transistors (transistors 201a to 201) of circuit 111 The channel width (or gate width) W of a pixel (such as L) is determined by the number of transistors (transistors) that the pixel has. Channel width (or similar) of transistors such as 801, 1301, 1311, etc. The gate width (W) can be made larger than W. In particular, the transient having an oxide semiconductor Because the off-current is small, even if the channel width (or gate width) W is increased, the shadow is not negatively affected. The resonance is weak. And the channel width (or gate width) of the transistor in circuit 111. By increasing W, pre-charging and inspection can be performed more quickly. The transistors (transistors 201a to 201L) of circuit 111 The channel length (or gate length) L of a pixel is determined by the number of transistors (transistors) that the pixel has. Channel length (or The gate length can be made larger than L.

[0085] (Embodiment 5) In this embodiment, transistors 201a to 201L, Transistors such as 801, 1301, and 1311 form the channel formation region. A transistor is applied in which the region is composed of oxide semiconductors.

[0086] As an oxide semiconductor, the In-Sn-Ga-Zn-O system oxide semiconductor is a quaternary metal oxide. Conductors, ternary metal oxides such as In-Ga-Zn-O oxide semiconductors and In-Sn-Zn -O-based oxide semiconductors, In-Al-Zn-O-based oxide semiconductors, Sn-Ga-Zn-O-based acids Iridescent semiconductors, Al-Ga-Zn-O based oxide semiconductors, or Sn-Al-Zn-O based acids In-Zn-O oxide semiconductors, which are metal oxides or binary metal oxides, Sn-Zn- O-based oxide semiconductors, Al-Zn-O-based oxide semiconductors, Zn-Mg-O-based oxide semiconductors, S n-Mg-O oxide semiconductors, In-Mg-O oxide semiconductors, In-O oxide semiconductors Using oxide semiconductors such as Sn-O-based oxide semiconductors or Zn-O-based oxide semiconductors This is possible. Alternatively, an oxide semiconductor in which SiO2 is added to the above oxide semiconductor may also be used.

[0087] Furthermore, oxide semiconductors include InMO3(ZnO) m We use substances denoted as (m>0). This is possible. Here, M is one or more selected from Ga, Al, Mn, and Co. This indicates a metallic element. For example, M could be Ga, Ga and Al, Ga and Mn, or Ga and Examples include Co., InMO3(ZnO). m Oxide semiconductors with a structure represented by (m>0) Among these, an oxide semiconductor with a structure containing Ga as M is the In-Ga-Zn-O oxide described above. We will refer to it as a semiconductor, and its thin film as an In-Ga-Zn-O system film.

[0088] One method for fabricating a transistor in which the channel formation region is composed of an oxide semiconductor is This will be explained with reference to Figure 12.

[0089] Figures 12(A) to (D) show examples of the cross-sectional structure of a transistor. The transistor 410 shown in A) through (D) is a bottom gate type called channel etch type. It is one of the structures.

[0090] Furthermore, Figures 12(A) to (D) show single-gate transistors, but it is not necessary to Depending on the requirements, a transistor with a multi-gate structure having multiple channel formation regions may be used. It is possible.

[0091] The transistor 410 is fabricated on the substrate 400 using Figures 12(A) to (D) below. Let me explain the process.

[0092] First, a conductive film is formed on a substrate 400 having an insulating surface, and then a first photolithograph is used. The gate electrode layer 411 is formed by the following process.

[0093] There are no major restrictions on the substrates that can be used for the substrate 400 having an insulating surface, however few At the very least, it must have sufficient heat resistance to withstand subsequent heat treatments. For example, Using glass substrates such as barium borosilicate glass or aluminoborosilicate glass Yes, it is possible. Also, if the temperature of the subsequent heat treatment is high, the strain point of the glass substrate will be 730°C or higher. It would be good to use this.

[0094] An insulating film that serves as the underlayer may be provided between the substrate 400 and the gate electrode layer 411. It has the function of preventing the diffusion of impurity elements from the substrate 400, silicon nitride film, silicon oxide One or more films selected from a silicon nitride film, silicon nitride film, or silicon oxide film. It can be formed by a laminated structure.

[0095] Furthermore, the material of the gate electrode layer 411 is molybdenum, titanium, chromium, tantalum, tungsten. Metal materials such as stainless steel, aluminum, copper, neodymium, scandium, or materials with these as the main components It can be formed using alloy materials in a single layer or in a laminated manner.

[0096] Next, a gate insulating layer 402 is formed on the gate electrode layer 411.

[0097] The gate insulating layer 402 is formed using plasma CVD or sputtering, etc. Conc layer, silicon nitride layer, silicon oxide nitride layer, silicon nitride oxide layer, or aluminum oxide layer The aluminum layer can be formed as a single layer or in multiple layers. Furthermore, an oxide layer can be used as the gate insulating layer. High-k materials such as hafnium (HfOx) and tantalum oxide (TaOx) are used. It is also possible. The thickness of the gate insulating layer 402 shall be 100 nm or more and 500 nm or less, in the case of lamination. For example, a first gate insulating layer with a film thickness of 50 nm to 200 nm and a first gate A second gate insulating layer with a thickness of 5 nm to 300 nm is laminated on the insulating layer.

[0098] In this embodiment, the gate insulating layer 402 is made to a thickness of 100 nm by plasma CVD. The following silicon oxide nitride layer is formed.

[0099] Furthermore, a high-density plasma device is used to form a silicon oxide nitride film as the gate insulating layer 402. This may be done. Here, the high-density plasma apparatus is 1 × 1011 / cm 3 The above plasma density This refers to a device that can achieve a certain degree. For example, by applying microwave power of 3kW to 6kW. Plasma is generated to deposit an insulating film. The insulating film obtained using a high-density plasma device. Because it can form films of a consistent thickness, it has excellent step coverage. Furthermore, high-density plasma The insulating film obtained using this device allows for precise control over the thickness of the thin film.

[0100] The insulating film obtained by a high-density plasma apparatus is obtained using a conventional parallel-plate type PCVD apparatus. It is significantly different from the insulating film, and the etching speed was compared using the same etchant. In that case, 10% or more or 20% of the insulating film obtained with a parallel-plate type PCVD apparatus As mentioned above, the insulating film obtained with a high-density plasma device can be described as a dense film.

[0101] Furthermore, the oxide semiconductor (high-purity oxide) that is converted to type i or substantially converted to type i in a later process. Because semiconductor materials are extremely sensitive to interface states and interface charges, the interface with the gate insulating layer is critical. This is important. Therefore, the gate insulating layer (GI) that comes into contact with the highly purified oxide semiconductor is High quality is required. Therefore, high-density plasma CVD using μ-wave (2.45 GHz) is This is preferable because it allows for the formation of a dense, high-quality insulating film with high dielectric strength. The close contact between the semiconductor material and the high-quality gate insulating layer reduces interface states and improves interface characteristics. This is because it can be made to be of good quality. Having good film quality as a gate insulating layer is important. Of course, reducing the interface state density with oxide semiconductors and forming a good interface is also important. It is essential.

[0102] Next, an oxide semiconductor film 4 with a thickness of 2 nm to 200 nm is placed on the gate insulating layer 402. 30 is formed. The oxide semiconductor film 430 is an In-Ga-Zn-O system or an In-Zn-O system. An oxide semiconductor film such as the following is used. In this embodiment, the oxide semiconductor film 430 is In -A film is deposited by sputtering using a Ga-Zn-O oxide semiconductor target. The cross-sectional view at the floor corresponds to Figure 12(A). Furthermore, the oxide semiconductor film 430 is composed of noble gases (representative). Typically, under an argon atmosphere, under an oxygen atmosphere, or under a noble gas (typically argon) and oxygen. It can be formed by sputtering in a mixed atmosphere.

[0103] Here, a metal oxide target containing In, Ga, and Zn (In2O3:Ga2O Using 3:ZnO (1:1:1 [molar ratio]), the distance between the substrate and the target is 1 00mm, pressure 0.2Pa, DC power supply 0.5kW, argon and oxygen (argon The film is deposited under an atmosphere of :oxygen = 30 sccm:20 sccm, oxygen flow rate ratio of 40%). Using a pulsed DC power supply can reduce the amount of powdery material generated during film formation, and improve film thickness distribution. This is preferable because it results in uniformity. The film thickness of the In-Ga-Zn-O system film is 5 nm to 200 nm. m or less. In this embodiment, the oxide semiconductor film is an In-Ga-Zn-O based metal. Using an oxide target, an In-Ga-Zn-O film with a thickness of 20 nm is produced by sputtering. The film is then formed. Next, the oxide semiconductor film 430 is formed into island-shaped layers by a second photolithography process. It is processed into an oxide semiconductor layer.

[0104] Next, the oxide semiconductor layer is dehydrated or dehydrogenated. The temperature of the heat treatment of 1 is 400°C or higher and 750°C or lower, preferably 400°C or higher and less than the distortion point of the substrate. Here, the substrate is introduced into an electric furnace, which is one of the heat treatment apparatuses, and after performing a heat treatment on the oxide semiconductor layer at 450°C for 1 hour in a nitrogen atmosphere, without being exposed to the atmosphere, re-mixing of water and hydrogen into the oxide semiconductor layer is prevented, and the oxide semiconductor layer 431 is obtained (see Fig. 12(B)). Note that the heat treatment apparatus is not limited to an electric furnace, and it may be provided with an apparatus that heats the object to be treated by heat conduction or heat radiation from a heating element such as a resistance heating element. For example, an RTA (Rapid Thermal Anneal) apparatus such as a GRTA (Ga s Rapid Thermal Anneal) apparatus or an LRTA (Lamp Rapid Thermal Anneal) apparatus can be used. The LRTA apparatus is an apparatus that heats the object to be treated by radiation of light (electromagnetic waves) emitted from a lamp such as a halogen lamp, a metal halide lamp, a xenon arc lamp, a carbon arc lamp, a high-pressure sodium lamp, or a high-pressure mercury lamp. The GRTA apparatus is an apparatus that performs a heat treatment using a high-temperature gas. As the gas, an inert gas such as argon or an inactive gas that does not react with the object to be treated by heat treatment, such as nitrogen, is used. For example, as the first heat treatment, the substrate may be moved and placed in an inert gas heated to a high temperature of 650°C to 7OO°C, heated for several minutes, and then GRTA may be performed by moving the substrate out of the inert gas heated to a high temperature. When GRTA is used, high-temperature heat treatment in a short time becomes possible.

[0105]

[0106]

[0107] ​​​​​​​​​​​​​​​​Furthermore, the atmosphere used for the first heat treatment may be nitrogen, or helium, neon, or argon. It is preferable that the noble gases and dry air do not contain water, hydrogen, etc. For example, heat treatment The purity of nitrogen, or noble gases such as helium, neon, or argon, introduced into the apparatus should be set to 6N (9 9.9999% or higher, preferably 7N (99.99999%) or higher (i.e., impurity concentration) It is preferable to set the concentration to 1 ppm or less, preferably 0.1 ppm or less.

[0108] Furthermore, the first heat treatment of the oxide semiconductor layer is the oxidation before processing into an island-shaped oxide semiconductor layer. This can also be done on a physical semiconductor film 430. In that case, after the first heat treatment, heating The substrate is removed from the device, and a second photolithography process is performed.

[0109] Furthermore, when forming an opening in the gate insulating layer 402, the process involves the oxide semiconductor film 430 This can be done before or after dehydration or dehydrogenation treatment.

[0110] Note that the etching of the oxide semiconductor film 430 here is limited to wet etching. Dry etching may also be used.

[0111] The etching gas used for the oxide semiconductor film 430 in dry etching contains chlorine. A gas (such as chlorine (Cl2) or boron chloride (BCl3)) is preferred.

[0112] The etching solution for the oxide semiconductor film 430 used in wet etching is phosphoric acid and vinegar. A solution of acid and nitric acid, or ITO07N (manufactured by Kanto Chemical Co., Ltd.), can be used.

[0113] Next, a metallic conductive film is formed on the gate insulating layer 402 and the oxide semiconductor layer 431. . The metal conductive film may be formed by sputtering or vacuum evaporation. As the material of the metal conductive film, aluminum (Al), chromium (Cr), copper (Cu), tantalum (Ta), titanium (Ti ), molybdenum (Mo), tungsten (W), neodymium (Nd), scandium (Sc ) elements selected therefrom, alloys containing the above-described elements as components, or combinations of the above-described elements [[ID=??]] alloys and the like can be mentioned. Further, a nitride film of the above-described elements may be used. Also, manganese (M n), magnesium (Mg), zirconium (Zr), beryllium (Be), yttrium (Y) materials selected from any one or more of them may be used. Further, the metal conductive film may have a single-layer structure or a laminated structure of two or more layers. For example, a single-layer structure of an aluminum film containing silicon, a two-layer structure in which a titanium film is laminated on an aluminum film, a three-layer structure in which a titanium film is laminated on a titanium film and then a titanium film is laminated on the aluminum film, and the like can be mentioned.

[0114] When heat treatment is performed after the metal conductive film, it is preferable to give the metal conductive film heat resistance that can withstand this heat treatment. [[ID=??]]

[0115] A resist mask is formed on the metal conductive film by the third photolithography process, and after selectively etching to form the source electrode layer 415a and the drain electrode layer 415b, the resist mask is removed (see Fig. 12(C)).

[0116] In this embodiment, a titanium film is used as the metal conductive film, an In-Ga-Zn-O-based oxide is used for the oxide semiconductor layer 431, and aqueous ammonia peroxide ( 31 wt% hydrogen peroxide solution: 28 wt% aqueous ammonia: water = 5:2:2) is used as the etchant for the titanium film. It should be noted that there seems to be an unclear tag "??" in the original text which is retained as is in the translation. If this is an error in the original, it may need to be corrected for a more accurate translation.​​​

[0117] In the third photolithography process, only a portion of the oxide semiconductor layer 431 is etched. This can result in an oxide semiconductor layer having grooves (recesses).

[0118] Furthermore, in order to reduce the number of photomasks and processes used in the photolithography process, A resist formed by a multi-gradation mask, which is an exposure mask where the light that passes through it has multiple intensities. The etching process may be performed using a mask. A resist formed using a multi-gradation mask. The mask has a shape with multiple film thicknesses, and its shape can be further deformed by ashing. Because it can do this, it can be used in multiple etching processes to process different patterns. Therefore, a single multi-tone mask can be used to create at least two different patterns. A corresponding resist mask can be formed. Therefore, the number of exposure masks can be reduced. Furthermore, the corresponding photolithography process can also be reduced, thus simplifying the overall process.

[0119] Next, gases such as nitrous oxide (N2O), nitrogen (N2), or argon (Ar) are used. The plasma treatment is performed. The surface of the oxide semiconductor layer exposed by this plasma treatment It removes adsorbed water and other substances attached to the surface. It also uses a plasma created by mixing oxygen and argon gases. You may proceed with the processing.

[0120] After plasma treatment, a protective layer that comes into contact with a portion of the oxide semiconductor layer without being exposed to the atmosphere. An oxide insulating layer 416, which will serve as an insulating film, is formed.

[0121] The oxide insulating layer 416 has a thickness of at least 1 nm, and is made using a sputtering method or similar process. The marginal layer 416 can be formed using a method that prevents the introduction of impurities such as water and hydrogen. When hydrogen is present in the oxide insulating layer 416, the hydrogen penetrates the oxide semiconductor layer, causing acid... The back channel of the monoxide semiconductor layer 431 becomes low-resistance (N-type), and the parasitic channel Therefore, the oxide insulating layer 416 is formed to be a film that contains as little hydrogen as possible. It is important not to use hydrogen in the film deposition method.

[0122] In this embodiment, a silicon oxide film with a thickness of 200 nm is used as the oxide insulating layer 416. The film is deposited using the tutter method. The substrate temperature during film deposition should be between room temperature and 300°C. In this embodiment, the temperature is set to 100°C. The silicon oxide film is deposited by sputtering using a rare gas (typically...). This can be done under an argon atmosphere, an oxygen atmosphere, or a noble gas (typically argon) and oxygen. It can be carried out under atmospheric conditions. Furthermore, silicon oxide targets can be used as targets. Alternatively, a silicon target can be used. For example, using a silicon target, A silicon oxide film can be formed by sputtering under oxygen and nitrogen atmospheres.

[0123] Next, a second additive is added under an inert gas atmosphere, a dry air atmosphere, or an oxygen gas atmosphere. Heat treatment (preferably between 200°C and 400°C, for example between 250°C and 350°C) is performed. For example, a second heat treatment is performed at 250°C for 1 hour under a nitrogen atmosphere. When this is done, a portion of the oxide semiconductor layer (channel formation region) comes into contact with the oxide insulating layer 416. It is heated in this state. This supplies oxygen to a part of the oxide semiconductor layer (the channel formation region). Furthermore, the boundary between the source electrode layer 415a or the drain electrode layer 415b and the oxide semiconductor layer is also determined. Near the surface, oxygen diffuses into the source electrode layer 415a or the drain electrode layer 415b. This forms the source region 414a and the drain region 414b.

[0124] Through the above process, the oxide semiconductor layer is dehydrated or dehydrogenated. After heat treatment, a portion of the oxide semiconductor layer (channel formation region) is selectively subjected to oxygen excess treatment. This state is assumed. Furthermore, a portion of the oxide semiconductor layer in an oxygen-rich state is designated as region 413 in the figure. As shown above, transistor 410 is formed through the above process.

[0125] Furthermore, a heat treatment is performed in air at a temperature between 100°C and 200°C for between 1 hour and 30 hours. This may be done. In this embodiment, the heat treatment is performed at 150°C for 10 hours. This heat treatment is constant You can maintain the heating temperature and heat it, or you can raise the heating temperature from room temperature to 100°C or 200°C. The process of raising the temperature and then lowering it from the heating temperature back to room temperature may be repeated multiple times.

[0126] A protective insulating layer may be formed on the oxide insulating layer 416. For example, by RF sputtering. A silicon nitride film is formed using this method. RF sputtering is suitable for mass production because it allows for the formation of a protective insulating layer. This is a preferred film method. The protective insulating layer is resistant to moisture, hydrogen ions, and OH - Contains impurities such as First, an inorganic insulating film is used to block these from entering from the outside, and then a silicon nitride film, nitrogen Aluminum oxide film, silicon nitride film, aluminum oxide nitride, etc. are used. Next, a protective insulating layer 403 is formed using a silicon nitride film as a protective insulating layer (Figure 12(D )reference).

[0127] In this embodiment, the oxide semiconductor layer of transistor 410 is made of n-type impurities, such as hydrogen. To remove impurities other than the main components of the oxide semiconductor, the material is designed to contain as few impurities as possible. By increasing the purity, it is made into true (type i), or substantially true. Rather than adding impurities to create type i, the process involves removing as many impurities as possible, such as hydrogen and water. It is characterized by producing a higher purity type i (intrinsic semiconductor) or something close to it. By doing so, the Fermi level (Ef) is brought to the same level as the true Fermi level (Ei). It can be done.

[0128] The band gap (Eg) of the oxide semiconductor is 3.15 eV, and the electron affinity (χ) is 4. It is said to be 0.3eV. Titanium (T) is used to make up the source electrode layer and drain electrode layer. i) The work function is approximately equal to the electron affinity (χ) of the oxide semiconductor. In this case, metal-acid At the ionized semiconductor interface, no Schottky-type barrier is formed for electrons.

[0129] For example, if the channel width W of the transistor is 1 × 10⁻⁶ 4 A device with a channel length L of 3 μm in μm. Even so, at room temperature, the off-current is 10 -13 A is less than or equal to 0.1V / de It is possible to have a cade (gate insulating layer thickness of 100 nm).

[0130] In this way, the oxide semiconductor is purified to the point where it contains as few impurities as possible other than its main components. This improves the operation of transistor 410.

[0131] The oxide semiconductors mentioned above suppress variations in electrical properties by reducing the presence of hydrogen and moisture, which are factors that cause these variations. Intentionally removing impurities such as hydroxyl groups or hydrides (also called hydrogen compounds), and impurities The acid, which is the main component material constituting the oxide semiconductor that would otherwise simultaneously decrease due to the material removal process, supplies the element. As a result, it is an oxide semiconductor that has been purified to a high purity and electrically converted to the I-type (intrinsic) state. Therefore, the less hydrogen in the oxide semiconductor, the better. Also, in the highly purified oxide semiconductor, the carriers are extremely few (close to zero), and the carrier density is less than 1×10

[0132] / cm 12 / cm 3 Preferably, it is less than 1×10 11 / cm 3 That is, the carrier density of the oxide semiconductor layer approaches zero as much as possible. Since there are extremely few carriers in the oxide semiconductor layer, the off-current of the transistor can be reduced. The smaller the off-current, the better. For the transistor, the current value per 1 μm of the channel width (w) is 100 aA / μm or less, preferably 10 zA (zeptoampere) / μm or less, and more preferably 1 zA / μm or less. Furthermore, since there is no pn junction and no hot carrier degradation, the electrical characteristics of these transistors are not affected.

[0133] By thoroughly removing the hydrogen contained in the oxide semiconductor layer in this way, a transistor using the highly purified oxide semiconductor in the channel formation region can make the off-current extremely small. That is, in the non-conducting state of the transistor, the oxide semiconductor layer can be regarded as an insulator and circuit design can be carried out. On the other hand, in the conducting state of the transistor, the oxide semiconductor layer can be expected to have a higher current supply capacity than a semiconductor layer formed of amorphous silicon.

[0134] Furthermore, thin-film transistors equipped with low-temperature polysilicon were fabricated using oxide semiconductors. Compared to the transistor, the off-current is estimated to be about 10,000 times larger. We are designing it. Therefore, in transistors with oxide semiconductors, low-temperature polysilicone When the retention capacitance is equivalent (approximately 0.1pF) to a thin-film transistor equipped with a , The voltage retention period can be extended by approximately 10,000 times. As an example, video display If performed at 60 frames per second, the retention period for one signal write is 10,000 times longer (16 It can be set to approximately 0 seconds. And even with a small number of image signal write cycles, the display unit Still images can be displayed.

[0135] (Embodiment 6) This embodiment describes an example of a pixel and a method for driving that pixel. In particular, memory An example of a pixel containing a display element having properties and an example of a method for driving such a pixel will be described.

[0136] Figure 13(A) shows an example of a pixel circuit diagram. Pixel 5450 is connected to transistor 5451, It has a capacitive element 5452 and a display element 5453. The first terminal of transistor 5451 is The second terminal of transistor 5451 is connected to the capacitive element 5452. It is connected to one electrode of the device and one electrode of the display element 5453 (also called the pixel electrode). The gate of the transistor 5451 is connected to wiring 5462. The other side of the capacitive element 5452 The electrode is connected to the wiring 5463. The other electrode of the display element 5453 is connected to electrode 5454 ( It is connected to a common electrode (common electrode), counter electrode, cathode electrode, etc.

[0137] Note that one electrode of the display element 5453 is referred to as electrode 5455.

[0138] Here, if we compare Figure 13(A) and Figure 10(A), transistor 5451 is The display element 5453 corresponds to the display element 802, and the capacitive element 5452 corresponds to capacitive element 804, wiring 5462 corresponds to wiring 104a, and wiring 5461 corresponds to wiring Compatible with 103a.

[0139] Furthermore, it is preferable that the display element 5453 has memory properties. The driving method for the indicator element 5453 is a microcapsule type electrophoresis method, microcup Type electrophoresis, horizontal-movement electrophoresis, vertical-movement electrophoresis, twist-ball method Formula, powder transfer method, electronic powder fluid (registered trademark) method, cholesteric liquid crystal element, chiral network Examples include matic liquid crystals, antiferroelectric liquid crystals, and polymer-dispersed liquid crystals.

[0140] The voltage applied to such a display element 5453 is very high. Therefore, the display element 5453 The transistors that drive it require high voltage resistance. Furthermore, such high voltages Even when applied, the off-current needs to be low. Therefore, in such cases, By using an oxide semiconductor transistor as the transistor, the breakdown voltage is high, This makes it possible to create transistors with low off-current.

[0141] Figure 13(B) shows a cross-sectional view of a pixel using a microcapsule-type electrophoresis method. Electrode Multiple microcapsules 5480 are placed between 5454 and electrode 5455. The microcapsules 5480 are immobilized by resin 5481. Resin 5481 is bi It functions as an electrode. The resin 5481 may be translucent. However, the electrode 54 The space formed by 54, electrode 5455, and microcapsule 5480 contains air or It is possible to fill it with a gas such as an inert gas. In such cases, electrode 5454 A layer containing an adhesive or glue is formed on one or both of the electrode 5455 and the micro It would be good to secure capsule 5480.

[0142] Microcapsule 5480 consists of a membrane 5482, a liquid 5483, a particle 5484, and a particle 5 It has 485. Liquid 5483, particles 5484, and particles 5485 are film 5482 It is enclosed inside. The membrane 5482 is translucent. The liquid 5483 is a dispersion. It has a function. Liquid 5483 separates particles 5484 and 5485 into the membrane 5482. It can be dispersed. Furthermore, liquid 5483 should preferably be translucent and colorless. Child 5484 and particle 5485 are of different colors. For example, particle 5484 and particle 5 One of the particles, 485, is black, and the other of particle 5484 and particle 5485 is white. Good. Note that particle 5484 and particle 5485 have different charge densities and polarities. Assume that it is charged. For example, one of particle 5484 and particle 5485 is positively charged. The other particle, particle 5484, and particle 5485, should be negatively charged. This allows electrode 5 When a potential difference is generated between 454 and electrode 5455, particles 5484 and 5485 react to each other. It moves according to the field direction. In this way, the reflectivity of the display element 5453 changes, The gradation can be controlled. However, the structure of the microcapsule 5480 is as described above. It is not limited to this. For example, liquid 5483 can be colored. Another example is Therefore, it is possible for only one type of particle to be encapsulated in membrane 5482. Or, three types. It is possible to be of a different class or higher. As another example, particles 5484 and 5485 are white. And not only black, but also red, green, blue, cyan, magenta, yellow, emerald green You can choose from colors such as red and vermilion.

[0143] The film 5482 is a light-transmitting material (for example, acrylic resin (for example, polymethacrylic) Polymer resins such as methyl methacrylate, polyethyl methacrylate, urea resin, or gum arabic. These include fats, etc. Furthermore, the membrane 5482 should preferably be gelatinous. This provides flexibility. Because it is possible to improve bending strength and mechanical strength, it improves flexibility. It can be measured. Alternatively, the microcapsules 5480 can be packed tightly and uniformly into the film. It can be placed on substrates such as those shown.

[0144] For liquid 5483, a translucent oily liquid is preferable. Specifically, liquid 5 483 includes alcoholic solvents (e.g., methanol, ethanol, etc.), esters ( For example, ethyl acetate or butyl acetate), aliphatic hydrocarbons (for example, acetone, methyl ethyl acetate), etc. Ketones such as lucetone and methyl isobutyl ketone, pentane, hexane, or octane, etc. ), alicyclic hydrocarbons (e.g., cyclohexane or methylcyclohexane), long-chain hydrocarbons Aromatic hydrocarbons containing a carboxyl group, such as benzenes (e.g., benzene, toluene, xylene, (etc.), halogenated hydrocarbons (e.g., methylene chloride, chloroform, etc.), carboxylates This includes water or other oils, or at least two of these materials. The above mixture is present. Or, these materials or at least two or more of these materials Some mixtures contain surfactants or other additives.

[0145] Particles 5484 and 5485 are each composed of pigment. The pigments that make up 5485 are preferably of different colors. For example, particle 54 Particle 84 is composed of black pigment, and particles 5485 are composed of white pigment. I. Examples of black pigments include aniline black or carbon black. White face Examples of materials include titanium dioxide, zinc oxide, or antimony trioxide. These pigments contain charge control agents (e.g., electrolytes, surfactants, metal soaps, resins, rubbers, Oils, varnishes or compounds, etc.), dispersants (e.g., titanium-based coupling agents, aluminum (such as um-based coupling agents or silane-based coupling agents), lubricants, or stabilizers are added. It is possible to add it.

[0146] Figure 14(A) shows the case where the twist ball method is used as the display element 5453. A basic cross-sectional view is shown. The twist ball method changes the reflectivity by rotating the display element. This controls the grayscale. The difference from Figure 13(B) is between electrode 5454 and electrode 5455. In between, a twisted ball 5486 is placed instead of a microcapsule 5480. That is the case. The twist ball 5486 is formed around particle 5487 and particle 5487. It is composed of a cavity 5488 and a particle 5487 which each has a hemispherical surface. These are spherical particles painted in two different colors. Here, particle 5487 is Assume that the two hemispheres are painted white and black, respectively. A difference in charge density and polarity is provided. Therefore, a potential difference exists between electrode 5454 and electrode 5455. By creating a difference, particle 5487 can be rotated according to the direction of the electric field. Cavity 5488 is filled with liquid. This liquid is similar to liquid 5483. It can be used. However, the twist ball 5486 is not limited to the structure shown in Figure 14(A). It is not specified. For example, the structure of the twist ball 5486 may be a cylinder or an ellipse. It is possible.

[0147] Figure 14(B) shows that the display element 5453 uses a microcup type electrophoresis method. The image shows a cross-sectional view of the pixels when present. The microcup array consists of multiple microcups made of UV-curing resin, etc. Charged dye particles dispersed in dielectric solvent 5492 are placed in a microcup 5491 having a recess. It can be manufactured by filling with sub-component 5493 and sealing with sealing layer 5494. Sealing layer 5494 A sticky layer 5495 is preferably formed between the electrode 5455 and the dielectric solvent 5492. Therefore, it is possible to use an uncolored solvent, or to use a colored solvent such as red or blue. It is possible. Here, the case where there is one type of charged dye particle is illustrated, but if there are two types of charged dye particles... It may have more than one type. Because microcups have a wall structure that separates cells, impact and It is also sufficiently resistant to pressure. Alternatively, the contents of the micro cup are sealed, It can reduce the impact of environmental changes.

[0148] Figure 14(C) shows that the display element 5453 uses the electronic powder fluid (registered trademark) method. The cross-sectional view of the pixel in this case is shown. The electronic powder fluid (registered trademark) exhibits fluidity and the properties of the fluid and particles. It is a material that possesses both of the following properties. In this method, cells are separated by partition walls 5504, and electron powder is placed inside the cells. Fluid (registered trademark) 5502 and electronic powder fluid (registered trademark) 5503 are arranged. (Registered Trademark) 5502 and Electronic Powder Fluid (Registered Trademark) 5503, white particles and black particles It is advisable to use the following. However, Electronic Powder Fluid (registered trademark) 5502 and Electronic Powder Fluid (registered trademark) The types of 5503 are not limited to these. For example, Electronic Powder Fluid (registered trademark) 5502 and As for the electronic powder fluid (registered trademark) 5503, two colored particles other than white and black are used. This is possible. As another example, Electronic Powder Fluid (registered trademark) 5502 and Electronic Powder Fluid (registered trademark It is possible to omit either (standard) 5503 or the other.

[0149] As shown in Figure 13(A), a signal is assumed to be input to wiring 5461. In particular, Line 5461 carries a signal (e.g., a video signal) for controlling the gradation of the display element 5453. It shall be input. Thus, wiring 5461 is a signal line or source signal line (video). It shall have the function of a signal line or source line. Wiring 5462 is a signal line. The number is to be entered. In particular, the continuity state of transistor 5451 is to be entered in wiring 5462. A device to which signals for controlling (e.g., gate signals, scan signals, selection signals, etc.) are input. Thus, wiring 5462 is a signal line or gate signal line (scan signal line or gate signal line). It shall have the function of a wire. A predetermined voltage is supplied to wiring 5463. It shall be assumed that the wiring 5463 is connected to the capacitive element 5452. 5463 shall function as a power line or capacitance line. Electrode 5454 shall have A constant voltage is assumed to be supplied. Electrodes 5454 are located between multiple pixels or all pixels. In many cases, they are common. Therefore, electrode 5454 is a common electrode (common electrode, pair It shall have the function of a directional electrode or cathode electrode, etc.

[0150] Furthermore, the signals input to wiring 5461, wiring 5462, wiring 5463 and electrode 5454 The voltage is not limited to those mentioned above; various other signals or voltages can also be input. This is possible. For example, it is possible to input a signal to wiring 5463. Therefore, the potential of electrode 5455 can be controlled, and the signal input to wiring 5461 The amplitude voltage can be reduced. Therefore, wiring 5463 functions as a signal line. It is possible to have this. As another example, by changing the voltage supplied to electrode 5454 This allows the voltage applied to the display element 5453 to be adjusted. The amplitude voltage of the signal input to line 5461 can be reduced.

[0151] Transistor 5451 has the function of controlling the conductivity between wiring 5461 and electrode 5455. It has. Alternatively, transistor 5451 supplies the potential of wiring 5461 to electrode 5455. It has a function to control the timing of supply. Alternatively, transistor 5451 controls pixel 54 It has a function to control the timing of selecting 50. Thus, transistor 5451 It shall have the function of a switch or a selection transistor. The transistor 5451 is an N-channel type. Therefore, the transistor 5451 is connected to wiring 546 It turns on when an H signal is input to wire 2, and turns off when an L signal is input to wire 5462. This shall be the case. However, the polarity of transistor 5451 is not limited to N-channel type, The transistor 5451 can be a P-channel type. In this case, transistor 5 451 turns on when an L signal is input to wiring 5462, and when an H signal is input to wiring 5462 It is assumed that it will turn off when power is applied. The capacitive element 5452 has electrodes 5455 and wiring 5463 It has the function of maintaining the potential difference between it and the electrode 5455. Alternatively, the capacitive element 5452 has the function of maintaining the potential difference between it and the electrode 5455. It has a function to maintain the potential at a predetermined value. This turns off transistor 5451. However, voltage can continue to be applied to the display element 5453. In this way, the capacitive element 5 452 shall function as a retaining capacitance. However, transistor 5451 and The functions of the capacitive element 5452 are not limited to those mentioned above, but also include a variety of other functions. It is possible to do so.

[0152] Next, the general operation of the pixels in this embodiment will be described. The grayscale control of the display element 5453 This is achieved by applying a voltage to the display element 5453 and generating an electric field in the display element 5453. The voltage applied to the display element 5453 is controlled by the potential of electrode 5454 and the electrode This is done by controlling the potential of electrode 5455. Specifically, by controlling the potential of electrode 5454. This is done by controlling the voltage supplied to electrode 5454. The potential of electrode 5455 Control is performed by controlling the signal input to wiring 5461. Note that wiring 54 The signal input to 61 turns on transistor 5451, which in turn turns on electrode 5455 It is supplied to.

[0153] Furthermore, the strength of the electric field applied to the display element 5453, the direction of the electric field applied to the display element 5453, and By controlling one or more of the following, such as the time for which an electric field is applied to the display element 5453, the display element 5453 gradations can be controlled. Note that between electrode 5454 and electrode 5455, By preventing the generation of a potential difference, the gradation of the display element 5453 can be maintained.

[0154] Next, an example of the operation of the pixels in this embodiment will be described. The timing shown in Figure 15(A) The chart shows a period T which has an elective period and a non-elective period. Period T is the elective period. This refers to the period between the start time of one selection period and the start time of the next selection period.

[0155] During the selection period, an H signal is input to wiring 5462, so the potential of wiring 5462 (potential V5 The value (indicated as 462) is at an H level. Therefore, transistor 5451 turns on. As a result, the wiring 5461 and electrode 5455 become electrically connected. This allows the input to be received by the wiring 5461. The signal is supplied to electrode 5455 via transistor 5451. The potential of 5455 (indicated as potential V5455) is equal to the signal input to wiring 5461. This is the result. At this time, the capacitive element 5452 is the potential difference between the electrode 5455 and the wiring 5463. This is maintained. During the non-selection period, an L signal is input to wiring 5462, so wiring 5462 The potential becomes L level. Therefore, transistor 5451 turns off, so wiring 54 61 and electrode 5455 become non-conductive. As a result, electrode 5455 becomes floating. At that time, the capacitive element 5452 is between electrode 5455 and wiring 5463 during the selection period. The potential difference is maintained. Therefore, the potential of electrode 5455 is maintained during the selection period of wiring 546 The value remains equal to the signal input to 1. Thus, during the non-selection period, the transient Even when the starter 5451 is turned off, voltage can continue to be applied to the display element 5453. As described above, by controlling the signal input to wiring 5461 during the selection period, The voltage applied to the display element 5453 can be controlled. The gradation control is achieved by controlling the signal input to wiring 5461 during the selection period. It is possible to do so.

[0156] Note that the potential of electrode 5455 during the non-selective period is determined by the off-current of transistor 5451. feedthrough of transistor 5451 and charge injection of transistor 5451 Due to one or more of the effects of the selection, the signal input to wiring 5461 during the selection period This may differ from the above.

[0157] Furthermore, as shown in Figure 15(B), during a portion of the selection period, the potential of electrode 5455 is changed. It is possible to set the value to be equal to pixel 5454. As a result, pixel 5450 is selected. Even if the same signal is continuously input to pixel 5450 each time, electrode 545 By changing the potential of 5, the electric field strength of the display element 5453 can be changed. Therefore, afterimages can be reduced. Alternatively, the response speed can be increased. Alternatively, variations in response speed between pixels can be reduced, preventing unevenness or afterimages. This is possible. In order to realize such a driving method, the selection period is set to period T1 and period It is best to divide it into T2 and T1. Then, during period T1, the signal input to wiring 5461 It is preferable to set the value to be equal to that of electrode 5454. Note that during period T2, the wire 5461 is connected. The signal applied can be set to various values ​​to control the grayscale of the display element 5453. If the time of period T1 is too long, the time to write a signal for controlling the gradation of the display element 5453 into the pixel 5 450 will become short. Therefore, it is preferable that the period T1 is shorter than the period T2 . In particular, it is preferable that the period T1 is 1% or more and 20% or less of the selection period . More preferably, it is 3% or more and 15% or less. Even more preferably, it is 5% or more and 10% or less .

[0158] Next, an example of the operation of the pixel of the present embodiment for controlling the gradation of the display element 5453 by the time of applying a voltage to the display element 5453 will be described. The timing chart shown in FIG. 15(C) has a period Ta and a period Tb. And the period Ta has N (N is a natural number) periods T . The N periods T are each the same as the period T shown in FIGS. 15(A) to (B). The period Ta is a period for changing the gradation of the display element 5453 (for example, an address period, a writing period, an image rewriting period, etc.). The period Tb is a period for holding the gradation of the display element 5453 in the period Ta (holding period).

[0159] It is assumed that a voltage V0 is supplied to the electrode 5454. Therefore, the potential of the electrode 5454 is V0. A signal having at least three values is input to the wiring 5461 . The potentials of the three values of the signal are, respectively, a potential VH (VH > V0), a potential V0, and a potential VL (VL < V0). Therefore, it is assumed that the potential VH, the potential V0, and the potential VL are applied to the electrode 5455 .

[0160] By controlling the potential applied to the electrode 5455 in each of the N periods T included in the period Ta, the voltage applied to the display element 5453 can be controlled. For example, the electrode 5 ​​​​​​​​ When a potential VH is applied to electrode 455, the potential difference between electrode 5454 and electrode 5455 becomes: This results in VH-VL. This allows a positive voltage to be applied to the display element 5453. When a potential V0 is applied to electrode 5455, the electrical current between electrode 5454 and electrode 5455 The position difference becomes zero. This allows a voltage of zero to be applied to the display element 5453. When a potential VL is applied to electrode 5455, the relationship between electrode 5454 and electrode 5455 The potential difference becomes VL-VH. This applies a negative voltage to the display element 5453. This can be done. As described above, during the period Ta, a positive voltage (VH-VL) is applied to the display element 5453. This allows the following to be applied in various sequences: ) and negative voltage (VL-VH) and zero. This allows for fine control of the gradation of the display element 5453. Alternatively, it can reduce afterimages. This is possible. Or, the response speed can be increased.

[0161] In this embodiment, when a positive voltage is applied to the display element 5453, the display element 545 The third gray level is to approach black (also called the first gray level). A negative voltage is applied to the display element 5453. When pressure is applied, the grayscale of the display element 5453 approaches white (also called the second grayscale). When zero voltage is applied to the display element 5453, the gradation of the display element 5453 is maintained. It shall be done.

[0162] During period Tb, the signals input to wiring 5461 are those not written to pixel 5450. Therefore, in period Tb, the electrode 5455 is supplied during the Nth period T of period Ta. The potential is continuously applied to electrode 5455. In particular, during period Tb, display element 5453 It is preferable to maintain the gradation of the display element 5453 by not generating an electric field. Therefore, during the Nth period T of period Ta, a potential V0 is applied to electrode 5455. This is preferable. As a result, even during period Tb, the potential V0 is applied to the electrode 5455. Therefore, zero voltage is applied to the display element 5453. It can preserve tonal gradation.

[0163] Furthermore, the closer the next grayscale displayed by the display element 5453 is to the first grayscale, the longer the period Ta is It is good to increase the time that the potential VH is applied to electrode 5455. Alternatively, N periods T It is good to increase the number of times the potential VH is applied to electrode 5455. Alternatively, the period Ta Of these, the time from when potential VH is applied to electrode 5455 to when potential VL is applied to electrode 5455 It is good to lengthen the time obtained by subtracting the time spent. Alternatively, out of N periods T, the potential VH is at electrode 5 The number of times the potential VL is applied to electrode 5455 is calculated by subtracting the number of times the potential VL is applied to electrode 5455 from the number of times it is applied to 455. It's good to use a lot.

[0164] Furthermore, the closer the next grayscale displayed by the display element 5453 is to the second grayscale, the longer the period Ta is It is good to increase the time that the potential VL is applied to electrode 5455. Alternatively, N periods T It is good to increase the number of times the potential VL is applied to electrode 5455. Alternatively, the duration Ta Of these, the time from which potential VL is applied to electrode 5455 to the time from which potential VH is applied to electrode 5455 It is good to lengthen the time obtained by subtracting the time spent. Alternatively, out of N periods T, the potential VL is at electrode 5 The number of times the potential VH is applied to electrode 5455 is calculated by subtracting the number of times the potential VH is applied to electrode 5455 from the number of times it is applied to 455. It's good to use a lot.

[0165] Furthermore, during period Ta, the potentials applied to electrodes 5455 (potential VH, potential V0, potential V The combination of L) depends not only on the next grayscale that the display element 5453 will display, but also on the display It is possible for element 5453 to depend on the grayscale already displayed. Therefore, the next display Even if the grayscale displayed by element 5453 is the same, the grayscale already displayed by display element 5453 If the parameters differ, the combination of potentials applied to electrode 5455 may also differ.

[0166] For example, the grayscale that the display element 5453 is already displaying may be displayed during the period Ta for which it is displayed. The longer the time that potential VH is applied to electrode 5455, the longer the potential VH is applied to electrode 5455. The longer the time obtained by subtracting the time the potential VL is applied to electrode 5455 from the time it is applied, the more N units there are. During the period T, the more times the potential VH is applied to the electrode 5455, or the more N periods there are. Of T, the number of times the potential VH is applied to electrode 5455 is the number of times the potential VL is applied to electrode 5455. The greater the value obtained by subtracting the number of times it occurs, the longer the potential VL is applied to electrode 5455 during the period Ta. It is good to increase the duration. Alternatively, during N periods T, the potential VL is applied to electrode 5455. It is good to increase the number of times it is done. Alternatively, during the period Ta, the potential VL is applied to electrode 5455. It is best to lengthen the time obtained by subtracting the time the potential VH is applied to electrode 5455 from the time it is applied. Alternatively, the number of times the potential VL is applied to electrode 5455 during N periods T is calculated from the potential VH It is good to increase the number of times obtained by subtracting the number of times the signal is applied to electrode 5455. This will reduce the afterimage. It can be reduced.

[0167] As another example, the grayscale that the display element 5453 is already displaying is set to a period Ta for display. In this case, the longer the time that the potential VL is applied to electrode 5455, the longer the potential VL is applied to electrode 5455. The longer the time obtained by subtracting the time the potential VH is applied to electrode 5455 from the time applied to the electrode, the longer the time. The more times the potential VL is applied to the electrode 5455 during N periods T, or the more times N After a period T, the number of times the potential VL is applied to electrode 5455 determines the potential VH to electrode 5455. The greater the value obtained by subtracting the number of times given, the greater the potential VH that is applied to electrode 5455 during the period Ta. It is good to increase the duration of this. Alternatively, during N periods T, the potential VH may be at electrode 5455. It is good to increase the number of times it is given. Alternatively, during the period Ta, the potential VH should be at electrode 5455. If you make the time obtained by subtracting the time the potential VL is applied to electrode 5455 from the given time longer, Good. Alternatively, the number of times the potential VH is applied to electrode 5455 during N periods T is calculated from the potential It is good to increase the number of times VL is applied to electrode 5455 minus the number of times VL is applied. The image can be reduced.

[0168] Note that the N periods T are all of equal length. This is not limited to this. For example, at least two of the N periods T are different from each other. It is possible for the length to be such that... In particular, it is good to weight the lengths of N periods T. Example For example, if N=4, then if the length of the first period T is time h, then the length of the second period T is Let the interval be time h × 2. Let the length of the third period T be time h × 4. The length of the period T can be set to time h × 8. In this way, the lengths of the N periods T are weighted. By doing so, the number of times pixel 5450 is selected can be reduced, and the display element 54 The time for which voltage is applied to 53 can be precisely controlled. Therefore, power consumption can be reduced. It is possible.

[0169] Furthermore, it is possible to selectively apply potentials VH and VL to electrode 5454. In this case, it is preferable to selectively apply potentials VH and VL to electrode 5455. If a potential VH is applied to electrode 5454, then if a potential VH is applied to electrode 5455, A voltage of zero is applied to the display element 5453. When a potential VL is applied to the electrode 5455, A negative voltage is applied to the display element 5453. Meanwhile, a potential VL is applied to the electrode 5454. If this is the case, when a potential VH is applied to electrode 5455, a positive voltage is applied to display element 5453. When a potential VL is applied to electrode 5455, the display element 5453 shows zero voltage. It is applied. In this way, the signal input to wiring 5461 is converted to a binary (digital) signal. This allows for a simpler circuit to output a signal to wiring 5461. Cut.

[0170] Furthermore, during period Tb or part of period Tb, wiring 5461 and wiring 5462 are connected to signals. It is possible to not input this. In other words, wiring 5461 and wiring 5462 are left floating. It is possible to do so. Furthermore, during period Tb or part of period Tb, wiring 5463 is: It is possible to not input a signal. In other words, it is possible to leave wiring 5463 in a floating state. Furthermore, during period Tb or part of period Tb, voltage is supplied to electrode 5454. It is possible to do something that is not possible. In other words, it is possible to make electrode 5454 float.

[0171] (Embodiment 7) In this embodiment, an example of an electronic device will be described.

[0172] Figures 16(A) to 16(H) and 17(A) to 17(D) are diagrams showing electronic devices. Yes, these electronic devices consist of a casing 5000, a display unit 5001, a speaker 5003, and an LED. Lamp 5004, operation key 5005 (including power switch or operation switch), connection terminal Child 5006, Sensor 5007 (force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, Light, liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, electric current, voltage, power, radiation, (Including functions for measuring flow rate, humidity, gradient, vibration, odor, or infrared radiation), Microphone It can have n5008, etc.

[0173] Figure 16(A) shows a mobile computer, and in addition to the above, it includes switch 5009, It may have an infrared port 5010, etc. Figure 16(B) shows a portable device equipped with a recording medium. This is a type of image playback device (for example, a DVD player), and in addition to the above, a second display It may have a section 5002, a recording medium reading section 5011, etc. Figure 16(C) is a goggle. It is a type display, and in addition to the above, it has a second display unit 5002, a support unit 5012, It may have earphones 5013, etc. Figure 16(D) is a portable gaming machine, as described above. In addition to the above, it may also have a recording medium reading unit 5011, etc. Figure 16(E) is It is a projector and, in addition to the above-mentioned components, includes a light source 5033, a projection lens 5034, etc. This is possible. Figure 16(F) shows a portable gaming machine, and in addition to the above, a second display unit It may have a 5002, a recording medium reading unit 5011, etc. Figure 16(G) shows a television receiver. It is an image device, and in addition to the above-mentioned components, it may also have a tuner, an image processing unit, etc. (Figure) 16(H) is a portable television receiver, and in addition to the above, it is capable of transmitting and receiving signals. It may have a charger 5017, etc. Figure 17(A) is a display, and the above In addition to the above, it may have a support base 5018, etc. Figure 17(B) is a camera. In addition to the above, there is an external connection port 5019, a shutter button 5015, and an image receiving unit. 5016, etc. may be included. Figure 17(C) is a computer, as described above. In addition, there is a pointing device 5020, an external connection port 5019, and a reader / writer 5 021, etc. may be included. Figure 17(D) is a mobile phone, and in addition to the above, Antenna 5014, for 1-segment partial reception service for mobile phones and mobile terminals. It may have, etc.

[0174] The electronic devices shown in Figures 16(A) to 16(H) and Figures 17(A) to 17(D) are various It can have such functions.

[0175] The electronic device described in this embodiment has a display unit for displaying some kind of information. It is characterized by the following:

[0176] Next, we will explain some application examples of semiconductor devices.

[0177] Figure 17(E) shows an example of a semiconductor device being installed as an integral part of a building. ) consists of a housing 5022, a display unit 5023, a remote control device 5024 which is the operating unit, and a speaker 5 Includes 025, etc. The semiconductor equipment is wall-mounted and integrated with the building, and the installation space It can be installed without requiring a large space.

[0178] Figure 17(F) shows another example in which semiconductor equipment is installed within a building and integrated with the building itself. The display panel 5026 is installed together with the unit bath 5027, and the bather This allows viewing of the display panel 5026.

[0179] In this embodiment, walls and a unit bathroom were used as examples of buildings, but the actual form The configuration is not limited to this, and semiconductor devices can be installed in various types of buildings.

[0180] Next, we will show an example in which a semiconductor device is integrated with a mobile device.

[0181] Figure 17(G) shows an example of a semiconductor device installed in an automobile. (Display panel) 5028 is attached to the vehicle body 5029 and is controlled by the movement of the vehicle body or from inside or outside the vehicle body The system can display the entered information on demand. It also includes a navigation function. It's okay to do so.

[0182] Figure 17(H) shows an example of a semiconductor device being integrated with a passenger aircraft. Yes. Figure 17(H) shows a display panel 5031 on the ceiling 5030 above the seats of a passenger airplane. This diagram shows the shape of the unit when installed and in use. The display panel 5031 is located on the ceiling 50 30 is attached integrally with the hinge portion 5032, and the extension and retraction of the hinge portion 5032 Passengers will be able to view the display panel 5031. The display panel 5031 can be operated by passengers. It has the function of displaying information by doing so.

[0183] In this embodiment, examples of mobile bodies include automobile bodies and aircraft fuselages. However, this is not limited to motorcycles, four-wheeled vehicles (including automobiles, buses, etc.), and trains (monorails). It can be installed on various things, including railroads, railways, ships, etc.

[0184] In such electronic devices, transistors having oxide semiconductors with low off-current are used. By configuring the circuit in this way, it is possible to prevent unwanted current from leaking in. Yes, it is possible. Therefore, the circuit is more likely to function correctly. As a result, accurate display is possible. come. [Explanation of symbols]

[0185] 101 pixel section 102a pixels 102b pixels 102c pixels 102d pixels 103a, 103b, 103c, 103d, 103e, 103f, 103g, 103h, 103i, 103j, 103k, 103L wiring 104a Wiring 104b Wiring 111 circuits 201a, 201b, 201c, 201d, 201e, 201f, 201g, 201h, 201i, 201j, 201k, 201L transistors 202a Wiring 202b Wiring 202c wiring 203a Wiring 203b Wiring 203c wiring 400 circuit boards 402 Gate Insulation Layer 403 Protective insulating layer 410 transistors 411 Guard Layer 414a Source area 414b Drain area 415a Source electrode layer 415b Drain electrode layer 416 Oxide Insulating Layer 430 Oxide semiconductor film 431 Oxide semiconductor layer 501 Circuit 502 Circuit 503 Circuit 504 Circuit 511 circuit board 801 Transistor 802 display elements 802a Light-emitting element 803 Wiring 804 Capacitive element 805 Wiring 901 signal 902 cycles 903 period 904 period 905 period 906 Potential 907 signal 907a signal 907b signal 907c signal 908 signal 1301 Transistor 1303 Wiring 1304 Capacitive element 1305 Wiring 1311 Transistors

Claims

[Claim 1] It has a pixel section having multiple pixels, and a circuit arranged outside the pixel section, The circuit has a first transistor, The aforementioned pixel has a second transistor, Either the source or the drain of the first transistor is electrically connected to a data signal line. The source or drain of the first transistor, the other of which is electrically connected to the wiring, The source or drain of the second transistor is electrically connected to the data signal line. The first transistor and the second transistor each have an oxide semiconductor in their channel formation region. The channel width of the first transistor is greater than the channel width of the second transistor. The channel length of the first transistor is greater than the channel length of the second transistor. A semiconductor device in which the gate of the first transistor is in a floating state.

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