Semiconductor Device

Abstract

To solve such a problem that, as a display device has a higher definition, the number of pixels is increased, and the number of gate lines and the number of signal lines are increased, and when the number of the gate lines and the number of the signal lines are increased, it is difficult to mount an IC chip including a driver circuit for driving the gate and signal lines by bonding or the like, and thereby manufacturing cost is increased.SOLUTION: A pixel portion and a driver circuit for driving the pixel portion are provided over the same substrate, and at least a part of the driver circuit includes a thin film transistor using an oxide semiconductor interposed between gate electrodes provided above and below the oxide semiconductor. Manufacturing cost is reduced by providing the pixel portion and the driver portion over the same substrate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a semiconductor device using an oxide semiconductor and a manufacturing method thereof. [Background technology]

[0002] As typified by liquid crystal display devices, thin film transistors formed on flat plates such as glass substrates They are made of amorphous silicon and polycrystalline silicon. Thin-film transistors using GaN have low field-effect mobility, but they are suitable for enlarging the area of ​​glass substrates. On the other hand, thin film transistors using polycrystalline silicon have a field effect mobility of Although it is expensive, it requires a crystallization process such as laser annealing, which is necessary for enlarging the area of ​​glass substrates. It has the characteristic that it is not necessarily suitable for all applications.

[0003] In response to this, thin-film transistors are being fabricated using oxide semiconductors, and they are being used in electronic devices and optical devices. For example, zinc oxide and In-GaAs films are used as oxide semiconductors. Thin-film transistors are fabricated using a-Zn-O oxide semiconductors, and used as switches for image display devices. Technologies used in switching elements and the like are disclosed in Patent Documents 1 and 2. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-123861 A [Patent Document 2] JP 2007-096055 A Summary of the Invention [Problem to be solved by the invention]

[0005] Thin film transistors with a channel formation region in an oxide semiconductor are made of amorphous silicon. The oxide semiconductor film has a higher field effect mobility than the thin film transistors that use the oxide semiconductor film. Film formation is possible at temperatures below 300℃ using methods such as sputtering, and polycrystalline silicon The manufacturing process is simpler than that of thin film transistors using

[0006] Using such oxide semiconductors, thin film transistors can be formed on glass substrates, plastic substrates, etc. The display is then used for a liquid crystal display, an electroluminescent display, electronic paper, or the like. It is expected that this technology will be applied to display devices.

[0007] In addition, when the display area of ​​a display device is enlarged, the number of pixels increases, and the number of gate lines and signal lines also increases. In addition, as display devices become more highly precise, the number of pixels increases, and the number of gate lines and signal As the number of gate lines and signal lines increases, the number of drivers required to drive them also increases. It has become difficult to mount IC chips with operating circuits by bonding, etc., and manufacturing costs have increased. The number of cases increases.

[0008] Therefore, a thin film transistor using an oxide semiconductor is used for at least a part of a driver circuit for driving a pixel portion. One object is to reduce manufacturing costs by using transistors.

[0009] At least a part of the driving circuit for driving the pixel section is made of a thin-film transistor using an oxide semiconductor. When using a thin-film transistor, the transistor must have high dynamic characteristics (on-state characteristics and frequency characteristics (f The thin film transistor with high dynamic characteristics (on-state characteristics) is required. It is another object of the present invention to provide a driver circuit that can be driven at high speed. [Means for solving the problem]

[0010] Gate electrodes are provided above and below the oxide semiconductor layer, improving the on-state characteristics and reliability of the thin film transistor. In addition, a gate electrode provided below the oxide semiconductor layer and a gate insulating film formed on the oxide semiconductor layer A source electrode layer or a drain electrode layer is formed between the source electrode layer and the drain electrode layer. At least a part of the drain electrode layer is provided with low-resistance oxide semiconductor layers above and below the source region or drain region. The source electrode layer and the drain electrode layer are formed as first and second layers on the upper and lower sides. the source region or the first drain region, and the second source region or the second drain region It is a sandwiched structure.

[0011] In addition, the threshold voltage can be controlled by controlling the gate voltage applied to the upper and lower gate electrodes. The upper and lower gate electrodes may be electrically connected to each other to have the same potential. The gate electrodes may be connected to separate wirings to have different potentials. For example, the threshold voltage may be set to zero. Or, it can be made closer to zero, and the driving voltage can be reduced to reduce power consumption. In addition, the threshold voltage can be set to a positive value to function as an enhancement type transistor. In addition, the threshold voltage can be set negative to function as a depletion type transistor. It is also possible.

[0012] For example, a combination of enhancement and depletion type transistors An inverter circuit (hereinafter referred to as an EDMOS circuit) can be configured and used in a drive circuit. The driving circuit has at least a logic circuit section and a switch section or a buffer section. The logic circuit section is configured to include the above EDMOS circuit. It is preferable to use a thin film transistor capable of passing a large on-current for the depth portion. A recessed type transistor or a thin film transistor having gate electrodes above and below an oxide semiconductor layer. A transistor is used.

[0013] Fabricate thin-film transistors with different structures on the same substrate without significantly increasing the number of processes For example, a driving circuit for high-speed operation can be provided with gate electrodes above and below the oxide semiconductor layer. The EDMOS circuit is made up of thin-film transistors with electrodes, and the pixel section is made up of oxide semiconductor A thin film transistor having a gate electrode only below the body layer may be used.

[0014] When the threshold voltage of the n-channel TFT is positive, it is called an enhancement type transistor. When the threshold voltage of the n-channel TFT is negative, it is called a depletion-type transistor. This definition will be followed throughout the specification.

[0015] In addition, the material of the gate electrode provided above the oxide semiconductor layer is not particularly limited as long as it is a conductive film. Not specified, aluminum (Al), copper (Cu), titanium (Ti), tantalum (Ta), W, Molybdenum (Mo), Chromium (Cr), Neodymium (Nd), Scandium The element selected from the group consisting of Sc, Cr, and Cr, or an alloy containing the above-mentioned elements is used. The gate electrode is not limited to a single layer containing the above-mentioned elements, but may be a laminate of two or more layers. Cut.

[0016] In addition, the gate electrode provided above the oxide semiconductor layer is made of the same material as the pixel electrode (transparent In the case of a transmission type display device, a transparent conductive film, etc. can be used. For example, In the same process as the process of forming the pixel electrode electrically connected to the thin film transistor, the oxide The gate electrode can be formed above the semiconductor layer. This greatly reduces the process. Without increasing the number of layers, a thin-film transistor with gate electrodes above and below the oxide semiconductor layer was formed. It can be achieved.

[0017] In addition, by providing a gate electrode above the oxide semiconductor layer, the signal In the bias-thermal stress test (hereinafter referred to as BT test) to check the reliability, It is possible to reduce the amount of change in the threshold voltage of the thin film transistor before and after the test. In particular, by providing a gate electrode above the oxide semiconductor layer, reliability can be improved. can.

[0018] In addition, an ohmic contact is required between the source electrode and the oxide semiconductor layer. It is desirable to reduce the contact resistance as much as possible. An ohmic contact with the conductor layer is required, and the contact resistance must be as low as possible. Therefore, it is desirable to reduce the amount of the gate insulating layer between the source electrode and the drain electrode, and between the gate insulating layer and the The oxide semiconductor layer is preferably formed between the source electrode and the drain electrode and between the oxide semiconductor layer and the oxide semiconductor layer. By intentionally providing high concentration source and drain regions, ohmic contacts can be obtained. In this specification, the contacts are formed to function as source and drain regions. The low-resistance oxide semiconductor layer has n-type conductivity. + Also called layer.

[0019] The configuration of the invention disclosed in this specification includes a first gate electrode on an insulating surface; A first insulating layer is disposed above the first insulating layer, and a first source region or a first drain region is disposed above the first insulating layer. and a source electrode or a drain electrode above the first source region or the first drain region. a second source region or a second drain region above the source electrode and the drain electrode; An oxide semiconductor layer is provided above the second source region or the second drain region, and the oxide semiconductor layer is provided on the second source region or the second drain region. a second insulating layer and a second gate electrode above the second insulating layer; and the oxide semiconductor layer is a first gate electrode formed on the first insulating layer and overlapping the first gate electrode; The first gate electrode is disposed between the source electrode and the drain electrode, and the second gate electrode is made of an oxide semiconductor. The semiconductor device is provided with a first gate electrode and a second gate electrode.

[0020] The above configuration solves at least one of the above problems.

[0021] In the above structure, the width of the second gate electrode is wider than the width of the first gate electrode. Thus, a voltage can be applied to the entire oxide semiconductor layer from the second gate electrode.

[0022] Alternatively, in the above configuration, the width of the first gate electrode is narrower than the width of the second gate electrode. By doing so, the area overlapping with the source electrode or drain electrode is reduced, thereby reducing the parasitic capacitance. Furthermore, the width of the second gate electrode can be set to be equal to or smaller than the width between the source electrode and the drain electrode. By making the gap narrower than the gap, the parasitic capacitance is reduced by not overlapping with the source or drain electrodes. The amount may be further reduced.

[0023] The method for manufacturing the above structure is also characterized by the fact that the first gate electrode is formed on an insulating surface. a first gate electrode is formed, a first insulating layer is formed on the first gate electrode, and a first insulating layer is formed on the first insulating layer. forming a first source region or a first drain region, A source electrode or a drain electrode is formed on the gate region, and a A second source region or a second drain region is formed, and the first insulating layer, the second source region, After performing a plasma treatment on the second source region and the second drain region, forming an oxide semiconductor layer on the insulating region; forming a second insulating layer covering the oxide semiconductor layer; The method for manufacturing a semiconductor device includes forming a second gate electrode on the insulating layer of the second semiconductor device. In the present invention, the second gate electrode is formed using the same material and the same mask as the pixel electrode. This allows the manufacturing process to be completed without significantly increasing the number of steps.

[0024] In addition, the configuration of another invention has a pixel section and a driving circuit, and the pixel section has at least a first oxide The driving circuit includes a first thin film transistor having a second oxide semiconductor layer. a second thin film transistor having a second oxide semiconductor layer and a third thin film transistor having a third oxide semiconductor layer. a third thin film transistor having a third oxide a first gate electrode below the oxide semiconductor layer and a second gate electrode above the third oxide semiconductor layer. and an electrode. At least a portion of the third oxide semiconductor layer is provided with source regions above and below. A second gate electrode is disposed between the source electrode and the drain electrode having drain regions above and below. The gate electrode of the semiconductor device overlaps with the third oxide semiconductor layer and the first gate electrode.

[0025] In the above-mentioned structure, the first thin film transistor of the pixel portion is electrically connected to the pixel electrode, The electrode is made of the same material as the second gate electrode of the driver circuit, so that the number of processes is not increased. It can be made.

[0026] In the above-mentioned structure, the first thin film transistor of the pixel portion is electrically connected to the pixel electrode, The electrode is made of a material different from that of the second gate electrode of the driving circuit. For example, the pixel electrode is made of a transparent conductive film. By forming the second gate electrode of the driving circuit using an aluminum film, It is possible to reduce the resistance.

[0027] In the above configuration, the first gate electrode and the second gate electrode are set to the same potential, Since gate voltages can be applied from above and below the oxide semiconductor layer, the current is The current that can be supplied can be increased.

[0028] In the above structure, the first gate electrode and the second gate electrode are set to different potentials. For example, the threshold voltage can be set to zero or close to zero, reducing the driving voltage and thus reducing power consumption. It is possible to reduce the force.

[0029] The third oxide semiconductor layer of the driver circuit overlaps with the first gate electrode via the first insulating layer. and overlaps with the second gate electrode via the second insulating layer, thus forming a so-called dual gate structure. It is made of.

[0030] In addition to liquid crystal display devices, semiconductor devices having driver circuits include light emitting devices using light emitting elements. Examples of such display devices include optical display devices and display devices that use electrophoretic display elements and are also called electronic paper. .

[0031] In this specification, the term "display device" refers to an image display device, a light-emitting device, or a light Also refers to connectors, such as FPC (Flexible Printed Circuit). inted circuit) or TAB (Tape Automated Bon ding tape or TCP (Tape Carrier Package) is used. Modules with printed wiring boards attached to the ends of TAB tape or TCP or the display element is mounted with an IC (integrated circuit) by the COG (Chip On Glass) method. The display device also includes all modules in which a display circuit (or other circuit) is directly mounted.

[0032] In a light-emitting display device using a light-emitting element, a pixel portion has a plurality of thin film transistors. In the elemental portion, the gate electrode of a thin film transistor and the source wiring of another transistor, The gate insulating film 10 has a portion for electrically connecting a drain wiring.

[0033] In addition, since thin-film transistors are easily damaged by static electricity, etc., It is preferable to provide a protection circuit for protecting the driver circuit on the same substrate as the line. is preferably configured using a nonlinear element using an oxide semiconductor.

[0034] The oxide semiconductor used in this specification is InMO3(ZnO). m (m>0) A thin film is formed and a thin film transistor is fabricated using the thin film as the semiconductor layer. , Ga, Fe, Ni, Mn, and Co. For example, M can be Ga, or it can be Ga and Ni or Ga and Fe. In addition, in the oxide semiconductor, M may contain other metal elements. In addition to the metal elements contained in the alloy, Fe, Ni and other transition metal elements, or the transition metal elements, In this specification, this thin film is called In-Ga- It is also called a Zn-O based non-single crystal film.

[0035] The In-Ga-Zn-O non-single crystal film is formed by sputtering and then heated at 200°C to 500°C. Typically, heating was performed at 300 to 400°C for 10 to 100 minutes. The crystal structure of the a-Zn-O non-single crystal film is amorphous, as observed by XRD analysis. do.

[0036] Oxide semiconductors, such as In-Ga-Zn-O non-single crystal films, have an energy gap ( Since the oxide semiconductor layer has a wide Eg, even if two gate electrodes are provided above and below the oxide semiconductor layer, the off-state The increase in current can be suppressed.

[0037] The ordinal numbers such as 1st and 2nd are used for convenience and do not indicate the order of steps or stacking. In addition, the specific names used in this specification are not intended to identify the invention. This does not indicate the Effect of the Invention

[0038] Peripheral circuits such as gate line driver circuits or source line driver circuits, or pixel sections, By forming a thin film transistor using an oxide semiconductor between the gate electrodes, Reduce manufacturing costs.

[0039] In the above-mentioned thin film transistor, a solenoid is provided above and below the source electrode or the drain electrode. A low-resistance oxide semiconductor layer functioning as a source region or a drain region is formed. Therefore, the area where the side surface of the source electrode or drain electrode contacts the oxide semiconductor layer is reduced. This makes it possible to increase the on-current of the thin film transistor. Between the source electrode and the drain electrode and the gate insulating layer, a semiconductor layer having a higher carrier concentration than the oxide semiconductor layer is provided. By intentionally providing high source and drain regions, ohmic contacts are formed. It is possible to form a [Brief description of the drawings]

[0040] [Figure 1] FIG. 2A is a cross-sectional view showing an example of the display device according to the first embodiment; FIG. 2B is a cross-sectional view showing another example of the display device according to the first embodiment; and FIG. [Diagram 2] 1A is a cross-sectional view of a semiconductor device according to a second embodiment, FIG. 1B is an equivalent circuit diagram, and FIG. [Diagram 3] FIG. 11 is a block diagram illustrating an entire display device according to a third embodiment. [Figure 4] 13 illustrates an arrangement of wiring, input terminals, and the like in a display device of Embodiment 3. [Diagram 5] FIG. 2 is a block diagram illustrating a configuration of a shift register circuit. [Figure 6] FIG. 1 illustrates an example of a flip-flop circuit. [Figure 7] FIG. 1 shows a layout diagram (top view) of a flip-flop circuit. [Figure 8] FIG. 4 is a timing chart for explaining the operation of the shift register circuit. [Figure 9] 10A to 10C illustrate a manufacturing method of a semiconductor device of Embodiment 4. [Figure 10] 10A to 10C illustrate a manufacturing method of a semiconductor device of Embodiment 4. [Figure 11] 10A to 10C illustrate a manufacturing method of a semiconductor device of Embodiment 4. [Figure 12] 10A to 10C illustrate a manufacturing method of a semiconductor device of Embodiment 4. [Figure 13] 10A to 10C illustrate a manufacturing method of a semiconductor device of Embodiment 4. [Figure 14]10A to 10C illustrate a semiconductor device of Embodiment 4. [Figure 15] 10A to 10C illustrate a semiconductor device of Embodiment 4. [Figure 16] 10A to 10C illustrate a semiconductor device of Embodiment 4. [Figure 17] FIG. 13 is a cross-sectional view illustrating a semiconductor device according to a fifth embodiment. [Figure 18] FIG. 13 illustrates a pixel equivalent circuit of the semiconductor device of Embodiment 6. [Figure 19] FIG. 13 is a cross-sectional view illustrating a semiconductor device according to a sixth embodiment. [Figure 20] 13A and 13B are a top view and a cross-sectional view illustrating a semiconductor device of Embodiment 6. [Figure 21] 13A and 13B are a top view and a cross-sectional view illustrating a semiconductor device of Embodiment 7. [Figure 22] FIG. 13 is a cross-sectional view illustrating a semiconductor device according to a seventh embodiment. [Figure 23] FIG. 1 is an external view showing an example of an electronic device. [Figure 24] FIG. 1 is an external view showing an example of a television device and a digital photo frame. [Diagram 25] FIG. 1 is an external view showing an example of a mobile phone. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following description, and various modifications in form and details are possible by those skilled in the art. The present invention is not to be construed as being limited to the description of the following embodiments. It is not something that can be achieved.

[0042] (Embodiment 1) FIG. 1A shows a first thin film transistor 480 used in a driver circuit and a second thin film transistor 480 used in a pixel portion. An example in which a thin film transistor 170 is provided over the same substrate is shown. 1 is an example of a cross-sectional view of the

[0043] The pixel section and the driver circuit are formed on the same substrate. The pixel electrode is formed using the second thin film transistor 170, which is an enhancement type transistor. The voltage applied to the second thin-film transistor 110 is switched on and off. The second thin film transistor 170 uses the oxide semiconductor layer 103. At a gate voltage of ±20V, the on-off ratio is 10 9 Contrast displayed because This improves the efficiency of the device, and also reduces leakage current, allowing for low power consumption operation. The on-off ratio is the ratio of the off current to the on current (I ON / I OFF ) and It can be said that the larger the capacitance, the better the switching characteristics, which contributes to improving the contrast of the display. The on-state current is the current that flows between the source and drain electrodes when the transistor is on. The off-state current is the current that flows through the source when the transistor is off. For example, in the case of an n-type transistor, the gate When the gate voltage is lower than the threshold voltage of the transistor, the In this way, in order to achieve high contrast and low power consumption, For this purpose, it is preferable to use an enhancement type transistor in the pixel portion.

[0044] In the driver circuit, a first gate electrode 401 and an oxide semiconductor layer 405 are provided below the oxide semiconductor layer 405. A thin film transistor 430 having a second gate electrode 470 above the semiconductor layer 405 is formed. At least one second gate electrode 470 is used. This second gate electrode 470 can also be called a back gate electrode. By forming a gate electrode, a via hole is formed to check the reliability of thin film transistors. In the thermal stress test (hereinafter referred to as BT test), the thin film transistor The amount of change in the threshold voltage of the transistor can be reduced.

[0045] The structure of the thin film transistor 430 will be described with reference to FIG. A first gate electrode 401 provided on a substrate 400 is covered with a first gate insulating layer 403. On the first gate insulating layer 403 overlapping the first gate electrode 401, + layer 408a and n + A layer 408b is provided. + Layers 408a and n + On layer 408b: A first wiring 409 or a second wiring 410 is provided. On the first wiring 409 or the second wiring 410 which functions as + Layers 406a and n + layer 40 6b and n + Layers 406a and n + On the layer 406b, an oxide semiconductor layer A second gate insulating layer 412 covering the oxide semiconductor layer 405 is provided. In addition, a second gate electrode 470 is provided on the second gate insulating layer 412 .

[0046] In addition, n + Layers 408a and n + At least a portion of the side surface of the layer 408b is made of an oxide semiconductor. In contact with the layer 405. + Layers 406a and n + Layer 406b is at least one of its upper surfaces. At least part of the first and second electrodes and at least part of the side surfaces of the first and second electrodes are in contact with the oxide semiconductor layer 405. Above and below the first wiring 409 and the second wiring 410,+ Since each layer is provided, the first distribution The area where the side surfaces of the line 409 and the second wiring 410 contact the oxide semiconductor layer 405 is reduced. It is possible.

[0047] n + The layer is an oxide semiconductor layer having a lower resistance than the oxide semiconductor layer, and The first wiring 409 functions as a source electrode layer, and the second wiring When the line 410 functions as a drain electrode layer, n + Layers 408a and n + Layer 406a is the first 1 and 2, which serve as source regions, + Layers 408b and n + Layer 406b is the first and The thin film transistor has multiple source regions, multiple drain regions, and By providing a drain region, the transistors can be more efficiently transmitted than when there is only one source or drain region. The on-state current of the transistor can be increased.

[0048] In addition, the first gate electrode 401 and the second gate electrode 470 are electrically connected to each other to have the same potential. When the gate electrodes are set to the same potential, gate voltages can be applied from above and below the oxide semiconductor layer. Therefore, the current flowing in the on state can be increased.

[0049] In addition, a control signal line for shifting the threshold voltage to the negative side is connected to the first gate electrode 401. 4, or the second gate electrode 470. The TFT may be a cushion type TFT.

[0050] A control signal line for shifting the threshold voltage to the positive side is connected to the first gate electrode 401, Alternatively, the enhancement layer 440 may be electrically connected to either of the second gate electrodes 470. The TFT may be a modulation type TFT.

[0051] In addition, the combination of two thin film transistors used in the driving circuit is not particularly limited. A thin film transistor having a gate electrode is used as a depletion type TFT, and two gates A thin film transistor having a gate electrode may be used as an enhancement type TFT. In this case, the gate electrodes are arranged above and below the oxide semiconductor layer as thin film transistors in the pixel section. The structure shall have each of these.

[0052] In addition, as a thin film transistor in a pixel portion, a gate electrode is provided above and below the oxide semiconductor layer. The gate electrode is made of oxide semiconductor as an enhancement type TFT for the driving circuit. The gate is a depletion type TFT of the driving circuit. A structure in which electrodes are provided above and below the oxide semiconductor layer may be used. A control signal line for controlling the value voltage is electrically connected to either the upper or lower gate electrode. The gate electrode connected thereto controls the threshold voltage.

[0053] In FIG. 1A, the second gate electrode 470 is the same as the pixel electrode 110 of the pixel portion. For example, in the case of a transmission type liquid crystal display device, the number of steps is reduced by using a transparent conductive film. However, there is no particular limitation. The width of the second gate electrode 470 is preferably set to be equal to or larger than that of the first gate electrode 40. 1 and further wider than the width of the oxide semiconductor layer, but there is no particular limitation. do not have.

[0054] FIG. 1B shows an example in which the material and width of the second gate electrode are different from those in FIG. 1A. FIG. 1B shows a second thin film transistor 170 connected to an organic or inorganic light emitting element. This is an example of a display device having a base portion.

[0055] In FIG. 1B, an electrode functioning as a second gate electrode of the thin film transistor 432 The material of 471 is metal material (aluminum (Al), copper (Cu), titanium (Ti), tantalum (Ta)). Ta (Ta), Tungsten (W), Molybdenum (Mo), Chromium (Cr), Neodymium (N d), Scandium (Sc), or an alloy containing the above elements. The width of the electrode 471 in cross section is narrower than that of the second gate electrode 470 in FIG. In addition, the width of the electrode 471 is narrower than that of the oxide semiconductor layer 405. Thus, the second gate electrode 471 is connected to the first wiring 409, the second wiring 410 and the second gate The area of ​​overlapping via the insulating layer 412 can be reduced, and the parasitic capacitance can be reduced. Cut.

[0056] The light-emitting element has at least a first electrode 472, a light-emitting layer 475, and a second electrode 474. In FIG. 1B, the electrode 471 is made of the same material as the first electrode 472 of the pixel portion, for example. The number of steps is reduced by using aluminum or the like, but there is no particular limitation. In B), the insulating layer 473 serves as a partition wall for insulating the first electrodes of adjacent pixels. It works like this.

[0057] FIG. 1C shows an example in which the material and width of the second gate electrode are different from those in FIG. 1A. In (C), the electrode 47 functions as the second gate electrode of the thin film transistor 433. The material of 6 is metal material (aluminum (Al), copper (Cu), titanium (Ti), tantalum ( Ta), tungsten (W), molybdenum (Mo), chromium (Cr), neodymium (Nd) , scandium (Sc), or an alloy containing the above elements. The width of the second gate electrode in cross section is narrower than that in FIG. 1(B). By narrowing the width of the first wiring 409, the second wiring 410 and the second gate insulating layer This can be achieved by using 412 to prevent overlapping, and further reduce the parasitic capacitance. The width of the electrode 476 shown in FIG. 1C is smaller than the distance between the first wiring 409 and the second wiring 410. In order to form the electrode 476 having such a narrow width, wet etching or the like is used. It is preferable to use a resist mask so that both ends of the electrode 476 are located inside the end of the resist mask. However, in FIG. 1C, a metal material different from that of the pixel electrode 110 is used, The number of photolithography steps for forming the electrode 476 is increased by one, and the number of masks is also increased by one. It will be done.

[0058] Gate line driving circuits or source line driving circuits used in liquid crystal displays, light emitting displays, and electronic paper Peripheral circuits such as circuits or pixel sections are sandwiched between two gate electrodes on the top and bottom. By using thin-film transistors made of semiconductors, high-speed operation and low power consumption can be achieved. In addition, it is possible to form both the pixel section and the driver circuit on the same substrate without significantly increasing the number of processes. By providing various circuits other than the pixel portion on the same substrate, the display The manufacturing costs of the device can be reduced.

[0059] In addition, a source region or a drain region may be provided above or below the source electrode or the drain electrode. As a result, a good connection is achieved between the source electrode or drain electrode, which is a metal layer, and the oxide semiconductor layer. This junction has a thermally stable operation compared to the Schottky junction. The transistors supply the carriers (source side) or absorb the carriers in the channel stably (drain side). This creates a resistance component at the interface with the source electrode (or drain electrode). It is important to provide a source region or a drain region in order to suppress the A resistive oxide semiconductor layer (n + By providing a layer, good mobility is achieved even at high drain voltages. It can be retained.

[0060] (Embodiment 2) In the first embodiment, one thin film transistor is described as the thin film transistor of the driving circuit. However, in this example, two n-channel thin film transistors are used to form the inverter circuit of the driver circuit. The thin film transistor shown in FIG. Since the thin film transistor 430 is the same as that shown in FIG. 1A of the first embodiment, the same parts are used. The explanation will be given using symbols.

[0061] The driver circuit for driving the pixel section is composed of an inverter circuit, a capacitor, a resistor, etc. When two n-channel TFTs are combined to form an inverter circuit, When forming a combination of ment type transistors and depletion type transistors ( In the following, it is called EDMOS circuit) and in the following, it is called enhancement type TFT. , called EEMOS circuits.

[0062] The cross-sectional structure of the inverter circuit of the driver circuit is shown in FIG. The first thin film transistor 430 and the second thin film transistor 431 are bottom gate thin film transistors. This is an example of a thin film transistor in which wiring is provided under a semiconductor layer.

[0063] In FIG. 2A, a first gate electrode 401 and a gate electrode 402 are provided on a substrate 400. The material of the first gate electrode 401 and the gate electrode 402 is molybdenum, titanium, chromium, or tantalum. Metallic materials such as chromium, tantalum, tungsten, aluminum, copper, neodymium, and scandium It can be formed in a single layer or a multilayer structure using a material or an alloy material mainly composed of the material. do.

[0064] For example, the two-layer laminate structure of the first gate electrode 401 and the gate electrode 402 may be made of Al. Two-layer laminate structure with a molybdenum layer on a aluminum layer, or a molybdenum layer on a copper layer or a titanium nitride or tantalum nitride layer on a copper layer. A three-layer structure is preferably a two-layer structure in which a titanium nitride layer and a molybdenum layer are laminated. The laminated structure is a tungsten layer or a tungsten nitride layer, and an aluminum and silicon layer. A titanium nitride layer or titanium layer is laminated with an alloy of aluminum and titanium or an alloy of aluminum and titanium. It is preferable to form a laminate in this manner.

[0065] Also, on the first gate insulating layer 403 covering the first gate electrode 401 and the gate electrode 402 On the other hand, a first wiring 409, a second wiring 410, and a third wiring 411 are provided. The first gate insulating layer 403 and the first wiring 409, the first gate insulating layer 403 and the second wiring 410, the first Between the gate insulating layer 403 and the third wiring 411, + layers 420, 421, 42 The second wiring 410 is connected to a contact hole formed in the first gate insulating layer 403. It is connected to the gate electrode 402 via a gate electrode 404 .

[0066] An oxide semiconductor layer 405 is provided above the first wiring 409 and the second wiring 410. , the first wiring 409 and the oxide semiconductor layer 405, and the second wiring 410 and the oxide semiconductor layer 405 Between + Layers 423 and 424 are provided. A second oxide semiconductor layer 407 is provided above the third wiring 411. Between the third wiring 411 and the oxide semiconductor layer 407, and between the third wiring 411 and the oxide semiconductor layer 407, + Layers 425 and 426, respectively, are provided.

[0067] In addition, n + The layers 420 to 426 are different from the oxide semiconductor layers 405 and 407 in that The wiring is an oxide semiconductor layer having low resistance and functions as a source region or a drain region. between the oxide semiconductor layer and + By using a layered structure, compared to a Schottky junction, This also ensures thermally stable operation.

[0068] The thin film transistor 430 includes a first gate electrode 401 and a first gate insulating layer 403. The first gate electrode 401 and the oxide semiconductor layer 405 overlap each other. The first wiring 409 This power supply line is a power supply line to which a negative voltage VDL is applied (negative power supply line). It may also be a power line (ground power line).

[0069] The second thin film transistor 431 includes a gate electrode 402 and a first gate insulating layer 40 a second oxide semiconductor layer 407 overlapping the gate electrode 402 via a third wiring 4 Reference numeral 11 denotes a power supply line (positive power supply line) to which a positive voltage VDH is applied.

[0070] FIG. 2C shows a top view of the inverter circuit of the driver circuit. The cross section taken along line Z1-Z2 corresponds to FIG. 2(A).

[0071] The equivalent circuit of the EDMOS circuit is shown in Fig. 2(B). 2(B), the thin film transistor 430 is an enhancement type n-channel transistor. The second thin film transistor 431 is a depletion type n-channel transistor. This is an example of a sta.

[0072] In order to make the thin film transistor 430 an enhancement-type n-channel transistor, In this embodiment, a second gate insulating layer 412 is formed over the oxide semiconductor layer 405. A second gate electrode 470 is provided on the gate insulating layer 412, and a voltage is applied to the second gate electrode 470. The threshold voltage of the thin film transistor 430 is controlled by the applied voltage.

[0073] The second gate insulating layer 412 also serves as a protective layer covering the second oxide semiconductor layer 407. It works.

[0074] In addition, in FIG. 2A and FIG. 2C, the second wiring 410 is a first gate insulating layer 403. 4 shows an example in which the gate electrode 402 is directly connected to the semiconductor substrate 401 through a contact hole 404 formed in the semiconductor substrate 401. However, this is not particularly limited, and a connecting electrode may be separately provided to connect the second wiring 410 and the gate electrode 402. Electrical connection may also be made.

[0075] In addition, this embodiment mode can be freely combined with the first embodiment mode.

[0076] (Embodiment 3) In this embodiment, a display device will be described with reference to block diagrams and the like.

[0077] FIG. 3A shows an example of a block diagram of an active matrix type liquid crystal display device. The liquid crystal display device shown in A) has a pixel section 3 having a plurality of pixels each having a display element on a substrate 300. 01, a scanning line driving circuit 302 for controlling the scanning lines connected to the gate electrodes of the pixels, and a selection and a signal line driver circuit 303 that controls input of a video signal to the selected pixel.

[0078] FIG. 3B shows an example of a block diagram of an active matrix type light emitting display device. The light-emitting display device shown in FIG. 3B has a pixel portion 3 having a plurality of pixels each having a display element on a substrate 310. 11, and a first scanning line driving circuit 312 for controlling the scanning lines connected to the gate electrodes of the pixels. and a second scanning line driver circuit 313, and a signal generator for controlling the input of a video signal to a selected pixel. A signal line driving circuit 314 is provided in each pixel. lm Transistor (hereafter referred to as TFT) and a current control TFT. In this case, in the light-emitting display device shown in FIG. 3B, A signal to be input to the first scanning line connected to the first scanning line is generated by a first scanning line driving circuit 312 and is controlled by a current. The signal input to the second scanning line connected to the gate electrode of the control TFT is the second scanning line driving signal. The signal input to the first scanning line and the signal input to the second scanning line are generated by the circuit 313. The signal to be output from the scanning line driver may be generated by a single scanning line driver circuit. The switching element is used to control the operation of the switching element depending on the number of TFTs it has. In this case, the first scanning lines may be provided in a plurality of pixels. The signals input to the scanning lines may all be generated by one scanning line driving circuit, or may be generated by multiple scanning lines. A driving circuit may be provided to generate each of these signals.

[0079] In this embodiment, the scanning line driver circuit 302, the first scanning line driver circuit 312, the second scanning line driver circuit 313, The embodiment in which the driving circuit 313 and the signal line driving circuits 303 and 314 are fabricated in the display device has been described. , the scanning line driving circuit 302, the first scanning line driving circuit 312, or the second scanning line driving circuit 3 A part of the signal line driver circuits 303 and 31 may be implemented as a semiconductor device such as an IC. A part of 4 may be implemented as a semiconductor device such as an IC.

[0080] FIG. 4 shows a signal input terminal 322, a scanning line 323, a signal line 324, and a non-line 1 is a diagram illustrating a positional relationship between a protection circuit including a semiconductor device and a pixel portion. On the substrate 320, scanning lines 323 and signal lines 324 are arranged to cross each other, forming a pixel section 327. The pixel portion 327 corresponds to the pixel portion 301 and the pixel portion 311 shown in FIG.

[0081] The pixel section 301 includes a signal line driver circuit 303 and a plurality of signal lines S arranged in a column direction. 1 to Sm (not shown) are connected to the signal line driving circuit 303, and the scanning line driving circuit 302 A plurality of scanning lines G1 to Gn (not shown) are arranged extending in the row direction from the The matrix is ​​connected to the driving circuit 302 and corresponds to the signal lines S1 to Sm and the scanning lines G1 to Gn. Each pixel is connected to a signal line Sj( signal lines S1 to Sm), scanning lines Gi (scanning lines G1 to Gn), ) is connected.

[0082] The pixel section 327 is configured with a plurality of pixels 328 arranged in a matrix. 3, a pixel TFT 329 connected to a scanning line 323 and a signal line 324, a storage capacitor 330, and a pixel It is configured to include an electrode 331 .

[0083] In the pixel configuration shown here, in the storage capacitor section 330, one electrode and the pixel TFT 329 The pixel electrode 3 is connected to the capacitance line 332, and the other electrode is connected to the capacitance line 332. 31 drives display elements (liquid crystal elements, light emitting elements, contrast media (electronic ink), etc.) The other electrodes of these display elements are connected to a common terminal 333. There are.

[0084] The protection circuit is disposed between the pixel section 327 and the signal line input terminal 322. The protection circuit is disposed between the scanning line driver circuit and the pixel section 327. A circuit is provided to prevent the scanning line 323, the signal line 324 and the capacitance bus line 337 from being damaged by static electricity or the like. A voltage is applied to the pixel TFT 329 so that the pixel TFT 329 and other components are not destroyed. The protection circuit is configured to release electric charge to the common wiring when a surge voltage is applied. It is being done.

[0085] In this embodiment, a protection circuit 334 is provided on the scanning line 323 side, and a protection circuit 335 is provided on the signal line 324 side. In this example, a protection circuit 336 is provided on a capacitive bus line 337. The location of the scanning line driver circuit is not limited to this. In this case, the protection circuit 334 does not need to be provided on the scanning line 323 side.

[0086] By using the TFTs shown in the first or second embodiment for each of these circuits, The advantages are as follows:

[0087] The driving circuit is roughly divided into a logic circuit section and a switch section or a buffer section. The TFT to be provided may be configured so that the threshold voltage can be controlled. Alternatively, it is preferable that the TFT provided in the buffer section has a large on-current. By providing a driver circuit having the TFT shown in the second embodiment, the TFT provided in the logic circuit section can be It is possible to control the threshold voltage of the FT, and the on / off state of the TFT provided in the switch section or buffer section It is possible to increase the current. Furthermore, the area occupied by the driving circuit is reduced, making it possible to realize a narrow frame. It also contributes to edge formation.

[0088] The shift register circuit constituting the scanning line driving circuit will be described below.

[0089] The shift register circuit shown in FIG. 5 has a plurality of flip-flop circuits 351 and a control signal line 352, control signal line 353, control signal line 354, control signal line 355, control signal line 356, and a reset line 357.

[0090] As shown in the shift register circuit of FIG. 5, in the flip-flop circuit 351, the first input A start pulse SSP is input to the terminal IN via the control signal line 352, and the following stages The input terminal IN is connected to the output signal terminal S of the previous flip-flop circuit 351. OUT is connected In addition, the reset terminal RES of the Nth stage (N is a natural number) is the same as that of the (N+3)th stage. Flip-flop circuit output signal terminal S out and reset wire 357. The clock terminal CLK of the Nth stage flip-flop circuit 351 is connected to a control signal line 353. Assuming that the first clock signal CLK1 is input through the (N+1)th stage, The clock terminal CLK of the flip-flop circuit 351 is connected to a second control signal line 354. The clock signal CLK2 is input to the (N+2)th flip-flop circuit 3 The third clock signal CLK is input to the clock terminal CLK of the clock circuit 51 via a control signal line 355. 3 is input to the clock terminal C of the (N+3)th flip-flop circuit 351. A fourth clock signal CLK4 is input to LK via a control signal line 356. The clock terminal CLK of the (N+4)th flip-flop circuit 351 receives the control signal A first clock signal CLK1 is input via a line 353. The flop circuit 351 has a gate output terminal G out Therefore, the Nth flip-flop circuit Output SRoutN.

[0091] Although the connection between the flip-flop circuit 351 and the power supply and the power supply line is not shown, The flip-flop circuit 351 is supplied with a power supply potential Vdd and a power supply potential GND via a power supply line. are being provided.

[0092] In addition, the power supply potential described in this specification corresponds to the potential difference when the reference potential is 0V. Therefore, the power supply potential is also called the power supply voltage, and the power supply voltage is also called the power supply potential. be.

[0093] In this specification, "A and B are connected" does not mean that A and B are directly connected. In addition to those that are connected electrically, A and B are also connected electrically. Being electrically connected means that there is an object between A and B that has some electrical effect. In this case, A and B are roughly the same node through the object. In the case of the MOS type, A and B are connected via a switching element such as a TFT, and the switching element When A and B are approximately at the same potential due to the conduction of The potential difference across the resistor element is small enough not to affect the operation of the circuit including A and B. When considering the circuit operation, A and B can be regarded as the same node. This indicates a state where there is no support.

[0094] Next, in FIG. 6, the flip-flop circuit 351 included in the shift register circuit shown in FIG. The flip-flop circuit 351 shown in FIG. 6 includes a logic circuit portion 361 and a switch The logic circuit section 361 includes a TFT 363 to a TFT 368. The switch section 362 includes TFTs 369 to 372. The path section is a circuit that outputs a signal to the switch section, which is a downstream circuit, in response to a signal input from the outside. The switch section is a circuit for switching between the inputs from the outside and the control circuit section. The switching of the TFT on or off depending on the signal input to the TFT, This is a circuit for outputting a current according to the size and structure of the device.

[0095] In the flip-flop circuit 351, the input terminal in is the gate terminal of the TFT 364, The reset terminal RES is connected to the gate terminal of the TFT363. The clock terminal CLK is connected to the first terminal of the TFT369 and the The power supply line to which the power supply potential Vdd is supplied is connected to the first terminal of TFT3 64, and the gate terminal and the second terminal of the TFT 366. The power supply line to which the potential GND is supplied is the second terminal of the TFT 363, the second terminal of the TFT 365, A second terminal of the TFT367, a second terminal of the TFT368, a second terminal of the TFT370, and a It is connected to the second terminal of TFT372. It is also connected to the first terminal of TFT363 and the second terminal of TFT364. 2nd terminal, 1st terminal of TFT365, gate terminal of TFT368, gate of TFT369 The first terminal of the TFT 366 and the gate terminal of the TFT 371 are connected to each other. Terminal 1 is the gate terminal of TFT365, the first terminal of TFT367, and the first terminal of TFT368. The gate terminal of the TFT 370 and the gate terminal of the TFT 372 are connected to each other. , Gate output terminal G out is connected to the second terminal of the TFT369 and the first terminal of the TFT370. Output signal terminal S out is the second terminal of TFT371 and TFT372 is connected to the first terminal of the

[0096] In this example, the TFTs 363 to 372 are all N-type TFTs. Explain the following.

[0097] A TFT has at least three terminals including a gate, a drain, and a source. The element has a channel forming region between a drain region and a source region, and the drain region A current can flow through the channel forming region and the source region. The drain may be switched depending on the TFT structure and operating conditions, so it is unclear which is the drain. It is difficult to identify which is the source and which is the drain. The regions that function as the source and drain are not called the source or drain, but are called, for example, are sometimes written as the first terminal and the second terminal. In this case, The terminal is referred to as a gate terminal.

[0098] Next, an example of a layout diagram of the flip-flop circuit 351 shown in FIG. 6 is shown in FIG.

[0099] The flip-flop circuit of FIG. 7 includes a power supply line 381 to which a power supply potential Vdd is supplied, a reset line 382, control signal line 353, control signal line 354, control signal line 355, control signal line 356, a control signal line 383, a power supply line 384 to which a power supply potential GND is supplied, a logic circuit unit 361, and The logic circuit section 361 includes a TFT 363 to a TFT 368. The switch section 362 includes TFTs 369 to 372. 7, the gate output terminal G out Wiring connected to output signal terminal S out Connected to The wiring is also shown.

[0100] In FIG. 7, a semiconductor layer 385, a first wiring layer 386, a second wiring layer 387, a third wiring layer The first wiring layer 386 is a gate insulating layer. The second wiring layer 387 is formed from a layer that forms a source electrode of the TFT. The third wiring layer 388 is formed from a layer that forms a pixel electrode in the pixel area. However, the present invention is not limited to this, and may be formed, for example, by using a layer that forms the third wiring layer 3 The wiring layer 88 may be formed as a separate wiring layer from the layer in which the pixel electrodes are formed.

[0101] The connections between the circuit elements in FIG. 7 are as described in FIG. 6. Since the flip-flop circuit to which the first clock signal is input is shown, Connections to signal lines 354 through 356 are not shown.

[0102] In the layout diagram of the flip-flop circuit in FIG. By controlling the threshold voltage of the TFT 366 or the TFT 367, the EDMOS circuit 373 is constructed. Typically, TFT366 is a depletion type, and TFT367 is a The switch section 362 is configured with an enhancement type EDMOS circuit 373. The TFT369 to TFT372 are dual-gate TFTs or depletion-type TFTs. In FIG. 6, the TFT 366 and the TFT The T367 is an EDMOS circuit shown in Figure 2. The connection locations are different.

[0103] The TFT366 or TFT367 is formed as a dual-gate TFT, and the back gate voltage By controlling the potential of the electrodes, it is possible to produce a depletion-type TFT or an enhancement-type TFT. It can be FT.

[0104] In FIG. 7, the control gate electrode is connected to the back gate electrode for controlling the threshold voltage of the TFT366. A control signal line 390 is provided separately to make the TFT 366 a depletion type. The potential of the back gate electrode is the power supply potential V This is a different potential from the power supply line 381 to which dd is supplied.

[0105] In FIG. 7, TFTs 369 to 372 are dual-gate TFTs, and In this example, the back gate electrode and the gate electrode have the same potential. The power supply potential Vdd applied to the power supply line is the same potential as that of the power supply line.

[0106] In this way, the TFTs arranged in the pixel section and the driver circuit of the display device are formed by forming an oxide semiconductor layer. The display can be formed using only n-channel TFTs.

[0107] In addition, the TFT 366 in the logic circuit section 361 passes a current according to the power supply potential Vdd. The TFT366 is a dual-gate TFT or a depletion-type TFT. By increasing the current flowing through the TFT, the size of the TFT can be reduced without compromising performance. It is possible to standardize the system.

[0108] In addition, in the TFT constituting the switch section 362, the amount of current flowing through the TFT is increased, And because it can be switched on and off quickly, it can be used without compromising performance. The area occupied by the TFT can be reduced. In addition, the area in which the TFTs 369 to 370 are arranged in the switch section 362 can be reduced. As shown in the figure, the FT 372 is a semiconductor layer 385 connected to a first wiring layer 386 and a third wiring layer 387. A dual gate TFT can be formed by sandwiching the two layers 88.

[0109] In addition, in FIG. 7, the dual gate type TFT has a semiconductor layer 385 and a first wiring layer 386. The third wiring layer is connected to the first wiring layer 386 through a contact hole 389 and has the same potential. Although an example in which the wiring layer 388 is sandwiched between the wiring layer 388 and the wiring layer 389 is shown, the present invention is not limited to this configuration. For example, a control signal line may be provided separately for the third wiring layer 388, and the potential of the third wiring layer 388 may be It may be configured to be controlled independently from the first wiring layer 386 .

[0110] In the layout diagram of the flip-flop circuit shown in FIG. The shape of the channel forming region of T372 may be U-shaped (U-shaped or horseshoe-shaped). In Figure 7, the size of each TFT is the same, but the output varies depending on the size of the downstream load. Signal terminal S out or gate output terminal G out The size of each TFT connected to the You can change it.

[0111] Next, the operation of the shift register circuit shown in FIG. 5 will be described with reference to the timing chart shown in FIG. FIG. 8 shows the control signal lines 352 to 356 shown in FIG. The start pulse SSP, the first clock signal CLK1 to the fourth clock signal CLK2 are supplied. CLK4, and the output signal terminals S of the first to fifth flip-flop circuits. out from The output signals Sout1 to Sout5 are shown. The reference characters given to the respective elements in FIG. 7 are used.

[0112] FIG. 8 shows a case where each of the TFTs in the flip-flop circuit is an N-type TFT. 1 is a timing chart showing the first clock signal CLK1 and the fourth clock signal C As shown in the figure, LK4 is shifted by 1 / 4 wavelength (a section divided by dotted lines). It has become.

[0113] First, during the period T1, a start pulse SSP is applied to the first stage flip-flop circuit. When the signal is input at the H level, the logic circuit section 361 turns on the TFTs 369 and 371 of the switch section. At this time, the first clock signal C Since LK1 is at the L level, Sout1 is at the L level.

[0114] During the period T1, the flip-flop circuits from the second stage onwards receive a signal at the IN terminal. Since no signal is input, the shifter does not operate and outputs a low level. In the following description, each flip-flop circuit of the register circuit outputs an L level. .

[0115] Next, in the period T2, in the first stage flip-flop circuit, the logic The circuit section 361 controls the switch section 362. In the period T2, the first clock signal CL Since K1 is at the H level, Sout1 is at the H level. Also, in the period T2, In the flip-flop circuit, Sout1 is input to the IN terminal at a H level, and the logic circuit section 361 turns on TFT369 and TFT371 of the switch section, and TFT370 and At this time, the second clock signal CLK2 is at the L level, so ut2 is at L level.

[0116] During the period T2, the flip-flop circuits from the third stage onwards receive a signal at the IN terminal. Since no input is input, the L level is output without operating.

[0117] Next, during a period T3, the first stage flip-flop circuit holds the state of the period T2. The logic circuit section 361 controls the switch section 362 so that The first clock signal CLK1 is at H level, and Sout1 is at H level. During the period T3, in the second stage flip-flop circuit, the logic circuit unit 3 61 controls the switch unit 362. In the period T3, the second clock signal CLK2 is H Since the third flip-flop in the period T3 is at the H level, Sout2 is at the H level. In the drop circuit, Sout2 is input to the IN terminal at a H level, and the logic circuit unit 361 is switched The TFTs 369 and 371 in the switch are turned on, and the TFTs 370 and 372 are turned off. At this time, the third clock signal CLK3 is at the L level, so Sout3 is at the L level. .

[0118] During the period T3, the flip-flop circuits from the fourth stage onwards receive a signal at the IN terminal. Since no input is input, the L level is output without operating.

[0119] Next, during a period T4, the first stage flip-flop circuit holds the state of the period T3. The logic circuit section 361 controls the switch section 362 so that Therefore, the first clock signal CLK1 is at the L level, and Sout1 is at the L level. During the period T4, the second stage flip-flop circuit is set to hold the state of the period T3. Thus, the logic circuit section 361 controls the switch section 362. Therefore, during the period T4, The second clock signal CLK2 is at H level, and Sout2 is at H level. During the period T4, in the third stage flip-flop circuit, the logic circuit section 3 61 controls the switch unit 362. During the period T4, the third clock signal CLK3 is H Since the fourth flip-flop in the period T4 is at the H level, Sout3 is at the H level. In the drop circuit, Sout3 is input to the IN terminal at a H level, and the logic circuit unit 361 is switched The TFT 369 and the TFT 371 of the switch 362 are turned on, and the TFT 370 and the TFT 372 are turned on. At this time, the fourth clock signal CLK4 is at the L level, so Sout 4 is L level.

[0120] During the period T4, the flip-flop circuits from the 5th stage onwards receive a signal at the IN terminal. Since no input is input, the L level is output without operating.

[0121] Next, during a period T5, the second stage flip-flop circuit holds the state of the period T3. The logic circuit section 361 controls the switch section 362 so that Therefore, the second clock signal CLK2 is at the L level, and Sout2 is at the L level. During the period T5, the third stage flip-flop circuit is set to hold the state of the period T4. Thus, the logic circuit unit 361 controls the switch unit 362. The third clock signal CLK3 is at H level, and Sout3 is at H level. During the period T5, the fourth-stage flip-flop circuit has the logic circuit unit 36 1 controls the switch unit 362. In the period T5, the fourth clock signal CLK4 is at the H level. Since this is a bell, Sout4 is at H level. Also, the flip-flop circuits from the 5th stage onwards The wiring of the circuit is the same as that of the first to fourth flip-flop circuits. The timing of the signals is similar, so the explanation is omitted.

[0122] As shown in the shift register circuit of Figure 5, Sout4 is the first stage flip-flop circuit. During the period T5, Sout4 becomes H level, and this signal The reset signal is input to the reset terminal RES of the first flip-flop circuit. As a result, the TFTs 369 and 371 of the switch section 362 are turned off, and the TFT 37 0 and TFT372 are turned on. Then, Sout1 of the first stage flip-flop circuit is , the L level is output until the next start pulse SSP is input.

[0123] By the above-described operation, the flip-flop circuits in the second and subsequent stages can The logic circuit is reset based on the reset signal output from the Sou As shown in t1 to Sout5, a signal with a waveform shifted by 1 / 4 wavelength of the clock signal is The shift register circuit may be an output shift register circuit.

[0124] In addition, the logic circuit section has enhancement and depletion types as flip-flop circuits. The switch section is equipped with a dual-gate TFT. By adopting this configuration, the amount of current flowing through the TFT constituting the logic circuit section 361 can be increased. It is possible to reduce the area occupied by the TFT and the amount of light generated by the TFT without degrading the performance. The area occupied by the circuitry configured can be reduced. In the case of TFTs, the amount of current flowing through the TFT is increased, enabling the device to switch between on and off quickly. Therefore, the area occupied by the TFT and the size of the TFT can be reduced without deteriorating the performance. Therefore, the area occupied by the circuitry formed by the above can be reduced. It is possible to achieve smaller size and higher performance.

[0125] In addition, a latch circuit, a level shifter circuit, and the like can be provided in the signal line driver circuit shown in FIG. A buffer section is provided at the final stage of sending signals from the signal line driver circuit to the pixel section, and the amplified signals is sent from the signal line driver circuit to the pixel section. For this reason, the buffer section is provided with a TFT with a large on-current. Typically, a dual-gate TFT or a depletion-type TFT is provided. Therefore, it is possible to reduce the area of ​​the TFT and the area occupied by the signal line driving circuit. Therefore, it is possible to realize a display device with a narrower frame, smaller size, and higher performance. The shift register, which is part of the signal line driver circuit, is required to operate at high speed. It is preferable to mount the display device using the above.

[0126] This embodiment mode can be freely combined with the first embodiment mode or the second embodiment mode. Cut.

[0127] (Embodiment 4) In this embodiment, a display device including the second thin film transistor 170 described in Embodiment 1 is The manufacturing process will be described with reference to FIGS.

[0128] In FIG. 9A, a substrate 100 having optical transparency is made of Corning 7059 glass or 1 Barium borosilicate glass, such as 737 glass, and aluminoborosilicate glass, etc. Any glass substrate can be used.

[0129] Next, a conductive layer is formed on the entire surface of the substrate 100, and then a first photolithography process is performed. A resist mask is formed, and unnecessary parts are removed by etching to form wiring and electrodes (gates). A gate line including a gate electrode 101, a capacitance line 108, and a first terminal 121 are formed. At this time, etching is performed so that at least the end of the gate electrode 101 is tapered. The cross-sectional view at this stage is shown in FIG. 9(A). The top view at this stage is shown in FIG. When the spin coating method is used to form the resist mask, the resist film To improve uniformity, a large amount of resist material and developer are used, and the excess material is consumed. Especially when the substrate becomes large, the deposition method using the spin coating method requires a large substrate. The plate rotating mechanism is large-scale, and there is a large amount of liquid material loss and waste liquid, which is a problem for mass production. In addition, when a rectangular substrate is spin-coated, circular irregularities occur around the axis of rotation. Therefore, the inkjet method and other droplet ejection methods and screen printing methods are used. A resist material film is selectively formed using the above, and exposed to light to form a resist mask. By selectively forming a resist material film, the use of the resist material can be reduced. This allows for a significant cost reduction due to the reduction in the amount of material used. It can also handle large area boards such as 100mm x 1250mm and 1150mm x 1300mm. Cut.

[0130] The gate wiring including the gate electrode 101, the capacitance wiring 108, and the first terminal 121 of the terminal portion are It is preferable to form it from a low-resistance conductive material such as aluminum (Al) or copper (Cu), but Aluminum alone has problems such as poor heat resistance and susceptibility to corrosion, so it is used as a heat-resistant conductive material. The heat-resistant conductive material is titanium (Ti), tantalum (Ta), , Tungsten (W), Molybdenum (Mo), Chromium (Cr), Neodymium (Nd), Sca or an alloy containing the above elements, or It is formed of an alloy film of a combination of elements, or a nitride film containing the above-mentioned elements as components.

[0131] Next, a gate insulating layer 102 is formed on the entire surface of the gate electrode 101. The film thickness of 2 is 50 to 400 nm by using a sputtering method or the like. When priority is given to the thickness, it is preferable that the gate insulating layer 102 be thick.

[0132] For example, a silicon oxide film is used as the gate insulating layer 102 by sputtering, and the thickness is 100 nm. Of course, the gate insulating layer 102 is not limited to such a silicon oxide film. Silicon oxide nitride film, silicon nitride film, aluminum oxide film, aluminum nitride film, Other insulating films such as aluminum film, aluminum oxide nitride film, and tantalum oxide film are used, and these materials The gate insulating layer 102 may be formed as a single layer or a laminated structure made of a material. When using a silicon oxynitride film or a silicon nitride film, impurities from the glass substrate For example, sodium or the like is prevented from diffusing and penetrating into an oxide semiconductor that will be formed later. It is possible.

[0133] Next, a second photolithography step is performed to form a resist mask and etch. By removing unnecessary parts, wiring made of the same material as the gate electrode and contact holes reaching the electrodes are formed. This contact hole is provided for direct connection with a conductive film to be formed later. For example, in the driving circuit section, the gate electrode and the source electrode or the drain electrode are directly in contact with each other. When forming a thin film transistor that is electrically connected to the gate wiring of the terminal part, A contact hole is formed. Note that a second photolithography process is performed here to Although an example of forming a contact hole for direct connection with a conductive film to be formed later has been shown, The gate electrode may be formed in the same process as the contact hole for connection to the pixel electrode. A contact hole reaching the layer may be formed and electrical connection may be made with the same material as the pixel electrode. If the electrical connection is made with the same material as the pixel electrode, the number of masks can be reduced by one. Cut.

[0134] Next, a first n + In this embodiment, the film is In-Ga-Zn- O-based non-single crystal film) is formed by sputtering. + The film is In2O3:Ga2O3:ZnO The deposition conditions were a pressure of 0.4 Pa and a power of 50 The sputtering process was performed at room temperature with an argon gas flow rate of 40 sccm. A target with In2O3:Ga2O3:ZnO=1:1:1 was intentionally used. Despite the fact that the In-Ga-Z film contains crystal grains with sizes of 1 nm to 10 nm immediately after deposition, In some cases, a non-single crystal film of nO may be formed. .1Pa~2.0Pa), power (250W~3000W: 8 inch diameter), temperature (room temperature~1 00℃), and by appropriately adjusting the film formation conditions of the reactive sputtering, the presence or absence of crystal grains and the crystal grains can be detected. It can be said that the density and diameter size of the first n can be adjusted in the range of 1 nm to 10 nm. + The thickness of the film is set to 5 nm to 20 nm. Of course, if the film contains crystal grains, the contained crystal grains are The size of the crystal grains does not exceed the thickness of the film. + The film thickness is , 5 nm.

[0135] Next, the first n+ A conductive film made of a metal material is formed on the film by sputtering or vacuum deposition. Here, the structure is a three-layer structure of a Ti film, an aluminum film containing Nd, and a Ti film. The elements are selected from Al, Cr, Ta, Ti, Mo, and W, or a mixture of the above elements. The conductive film may be an alloy film having the above-mentioned elements or an alloy film having the above-mentioned elements combined. A two-layer structure may be used, and a titanium film may be laminated on an aluminum film. Alternatively, a single layer structure of an aluminum film containing silicon or a single layer structure of a titanium film may be used.

[0136] Next, a second n + Film (In this embodiment, In-Ga-Zn-O system non-single crystal film ) is deposited by sputtering. + The membrane is the first + Using the same deposition conditions as the film The second n + The film has crystal grains of 1 nm to 10 nm in size immediately after deposition. The second n-type non-single crystal film is an In-Ga-Zn-O type non-single crystal film that may contain + The film thickness is 5 In this embodiment, the second n + The thickness of the film is 5 nm.

[0137] Gate insulating layer 102, first n + The film, the conductive film, and the second n + The film is made by sputtering. By appropriately switching the gas introduced into the chamber or the target to be installed, Continuous film formation without exposure to air reduces the amount of impurities. It is possible to prevent contamination. When continuous film formation is performed without exposure to the atmosphere, a multi-chamber system is used. It is preferable to use a manufacturing apparatus of the above type.

[0138] In this embodiment, the conductive film is made of In-Ga-Zn-O non-single crystal films on the top and bottom. The first and second n + In this case, the In-Ga-Zn-O non-monocrystalline The crystalline film can function as a barrier metal, so the conductive film can be made of a single aluminum film. By forming the conductive film as a single film of aluminum, the chamber This allows only one type of target to be installed in the target area, thereby reducing costs.

[0139] Next, a third photolithography process is performed to form a resist mask and perform etching. The unnecessary portions are removed to form a first source region 106a and a first drain region 106b. The source electrode layer 105a and the drain electrode layer 105b, + Membrane + layer 141 The etching method used in this case is wet etching or dry etching. In this example, wet etching was performed using ITO07N (manufactured by Kanto Chemical Co., Ltd.). By Ching, + After the layers 141a and 141b are formed, the Ti film is etched with Ammonia peroxide:ammonia:water = 5:2:2 was used to measure the amount of aluminum containing neodymium. The etching of the aluminum film is performed using a mixture of phosphoric acid, acetic acid, and nitric acid. This wet etching process creates a conductive layer consisting of a Ti film, an Al-Nd film, and a Ti film stacked in sequence. The film is etched to form the source electrode layer 105a and the drain electrode layer 105b. After that, using the same resist mask, wet etching was performed using ITO07N (Kanto Chemical Co., Ltd.) By this etching, a first source region 106a and a first drain region 106b are formed. A cross-sectional view at this stage is shown in FIG. 9(B). The top view at this stage corresponds to FIG. .

[0140] In the terminal portion, the connection electrode 120 is connected to the gate insulating layer through a contact hole formed in the gate insulating layer. The second n terminal 121 is directly connected to the first terminal 121 of the terminal portion. + film Consists of n + The layer 145 remains. Also, the layer 145 exists under the connection electrode 120 and is connected to the first terminal The first n overlapping with child 121 + Membrane + The layer 143 remains. is the second n + Membrane + The layer 144 remains, and below the second terminal 122 is the first n + Membrane + Layer 142 remains. The same process is used to form the source wiring or drain wiring and gate voltage of the thin film transistor of the driving circuit. In the capacitance section, the first and second electrodes overlapping the capacitance wiring 108 are directly connected. n + The membrane is removed.

[0141] Next, after removing the resist mask, a plasma is used to remove any dirt or other debris adhering to the surface. It is preferable to carry out the treatment. The cross-sectional view at this stage is shown in FIG. 9(C). Here, argon Reverse sputtering is performed by introducing gas and generating plasma using an RF power source, and the exposed The gate insulating layer is subjected to a plasma treatment.

[0142] A second n + Membrane n + layer 14 1a and 141b are provided, the plasma damage is reduced. + Membrane n + Since the layers 141a and 141b are provided, the source electrode layers 105a and An increase in wiring resistance due to oxidation of the drain electrode layer 105b can be suppressed.

[0143] Next, after the plasma treatment, an oxide semiconductor film is formed. By forming the oxide semiconductor film without using any insulating layer, it is possible to prevent dust and other foreign matter from being present at the interface between the gate insulating layer and the oxide semiconductor film. In this example, an 8-inch diameter In (indium), Ga ( Gallium) and Zn (zinc)-containing oxide semiconductor target (In2O3:Ga2O3 ZnO=1:1:1) was used, the distance between the substrate and the target was 170 mm, and the pressure was 0 The film is formed under argon or oxygen atmosphere at 0.4 Pa and a direct current (DC) power supply of 0.5 kW. A pulsed direct current (DC) power supply is preferred because it reduces dust and provides a uniform film thickness distribution. The thickness of the oxide semiconductor film is set to 5 nm to 200 nm. The thickness of the conductor film is 100 nm.

[0144] Next, a fourth photolithography process is performed to form a resist mask and perform etching. The unnecessary portions are removed to form the oxide semiconductor layer 103. The unnecessary parts were removed by wet etching using a SiO2 film (manufactured by Tokagaku Co., Ltd.) to form the oxide semiconductor layer. 103. Note that the first n + Membrane, second n + The oxide semiconductor film and the oxide semiconductor film are formed on the same etched surface. To use the chant, the etching here will create the first n + A part of the membrane and a second n + film The remaining second n + The membrane is This forms a first source region 146a and a second drain region 146b. The etching is not limited to wet etching, and dry etching may be used. Remove the gyst mask.

[0145] In the fourth photolithography step, the source electrode layer or the drain electrode layer The second terminals made of the same material as 105a and 105b are left on the terminal portion. 2 is a source wiring (a source wiring including source electrode layers or drain electrode layers 105a and 105b). ) is electrically connected to

[0146] Next, it is preferable to carry out a heat treatment at 200°C to 600°C, typically 300°C to 500°C. For example, place it in a furnace and heat treat it at 350℃ for 1 hour in a nitrogen or air atmosphere. Through the above steps, a thin film transistor 1 having the oxide semiconductor layer 103 as a channel formation region is formed. The cross-sectional view at this stage is shown in FIG. The surface view corresponds to FIG. 13. Note that the heat treatment is performed after the formation of the oxide semiconductor film. There are no particular limitations on the type of treatment, and the treatment may be performed, for example, after the formation of a protective insulating film.

[0147] Further, an exposed surface of the oxide semiconductor layer 103 may be subjected to oxygen radical treatment. By performing oxygen radical treatment, the thin film transistor can be made normally off. In addition, by performing radical treatment, the oxide semiconductor layer 103 can be etched. The damage can be repaired. Radical treatment includes O2, N2O, and preferably oxygen. It is preferable to carry out the process under an atmosphere of N2, He, or Ar. In addition, the above atmosphere may contain Cl2 or CF4. The radical treatment may be carried out in an atmosphere containing a hydrogen atom. stomach.

[0148] Next, a protective insulating layer 107 is formed to cover the second thin film transistor 170. 107 is a silicon nitride film, a silicon oxide film, a silicon oxynitride film, etc. obtained by a sputtering method. Silicon film, aluminum oxide film, aluminum nitride film, aluminum oxide nitride film, tantalum oxide A single layer of a tantalum film or a laminate of these films can be used. In the transistor, the protective insulating layer 107 functions as a second gate insulating layer. The second gate electrode is formed on the protective insulating layer 107. The protective insulating layer 107 has a thickness of 50 to 400 nm. When the yield of the thin film transistor is given priority, the thicker the protective insulating layer 107, the better. In addition, it is preferable that the protective insulating layer 107 is formed of a silicon oxynitride film or a silicon nitride film. When a film or the like is used, impurities that may adhere for some reason after the protective insulating layer 107 is formed, such as It is possible to block sodium and the like from diffusing and entering the oxide semiconductor.

[0149] Next, a fifth photolithography step is performed to form a resist mask and a protective insulating layer 1 A contact hole 125 reaching the drain electrode layer 105b is formed by etching in step 07. In addition, the contact hole 12 reaching the second terminal 122 is formed by the etching. 7. A contact hole 126 reaching the connection electrode 120 is also formed. Shown in Figure 10(B).

[0150] Next, after removing the resist mask, a transparent conductive film is formed. Indium oxide (In2O3) and indium tin oxide alloy (In2O3-SnO 2, ITO) is formed using a sputtering method or a vacuum deposition method. Etching of such materials is done with a hydrochloric acid based solution. However, etching of ITO in particular Residues are easily generated, so indium oxide zinc oxide alloy is used to improve etching processability. Gold (In2O3-ZnO) may also be used.

[0151] Next, a sixth photolithography step is performed to form a resist mask and perform etching. The unnecessary portions are removed to form the pixel electrode 110 in the pixel portion. In the roughening process, the same material as the pixel electrode 110 is used for a part of the driving circuit. Using this, an electrode layer (back gate electrode) for controlling the threshold voltage is formed on the oxide semiconductor layer. Note that the thin film transistor having a back gate electrode is the same as that shown in FIG. Since this is merely an illustration, a detailed description will be omitted here.

[0152] In addition, in this sixth photolithography step, the gate insulating layer 10 in the capacitance section 2 and the protective insulating layer 107 as dielectrics, the capacitance wiring 108 and the pixel electrode 110 form a storage capacitance. In this case, the gate insulating layer 102 and the protective insulating layer 107 are used as dielectrics. In the above example, the storage capacitor is formed by the capacitor wiring 108 and the pixel electrode 110. An electrode made of the same material as the source electrode or drain electrode is provided above the capacitance wiring. The electrodes, the capacitance wiring, and the gate insulating layer 102 between them are configured as a dielectric. A storage capacitor may be formed and its electrode may be electrically connected to the pixel electrode.

[0153] In the sixth photolithography step, the first terminal and the second terminal are resist-bonded. The transparent conductive film 128 and 129 formed on the terminal portion are left covered with a mask. 8 and 129 are electrodes or wiring used for connection with the FPC. The transparent conductive film 128 formed on the connected connection electrode 120 is an input terminal of the gate line. The transparent conductive film 1 formed on the second terminal 122 serves as a terminal electrode for connection. Reference numeral 29 denotes a connection terminal electrode that functions as an input terminal for the source wiring.

[0154] Next, the resist mask is removed, and the cross-sectional view at this stage is shown in FIG. The top view at this stage corresponds to FIG.

[0155] 15(A1) and 15(A2) are top views of the gate line terminal portion at this stage. FIG. 15(A1) is a cross-sectional view taken along line C1-C2 in FIG. 15(A2). In FIG. 15(A1), a transparent insulating film 154 is formed on the protective insulating film 154. The conductive film 155 is a terminal electrode for connection that functions as an input terminal. In the terminal portion, a first terminal 151 made of the same material as the gate wiring and a source A connection electrode 153 made of the same material as the source wiring is connected to the gate insulating layer 152 and the first source n formed of the same material as the region + The layers 160 are overlapped and electrically connected. The electrode 153 and the transparent conductive film 155 are connected to each other through a contact hole provided in the protective insulating film 154. The two terminals are directly connected to each other to provide electrical continuity.

[0156] FIG. 15(B1) and FIG. 15(B2) are a top view and a cross-sectional view of a source wiring terminal portion. Also, FIG. 15(B1) is taken along the line D1-D2 in FIG. 15(B2). In FIG. 15(B1), a transparent conductive film is formed on a protective insulating film 154. The conductive film 155 is a terminal electrode for connection that functions as an input terminal. In the terminal portion, an electrode 156 made of the same material as the gate wiring is connected to the source wiring. Below the second terminal 150 to which it is electrically connected, + through the layer 161 and the gate insulating layer 152 The electrode 156 is not electrically connected to the second terminal 150. If the second terminal 150 is set to a different potential, such as floating, GND, or 0V, It is possible to form a capacitance for noise countermeasures or a capacitance for static electricity countermeasures. The second terminal 150 is electrically connected to the transparent conductive film 155 via the protective insulating film 154. There are.

[0157] A plurality of gate lines, source lines, and capacitance lines are provided according to the pixel density. In addition, in the terminal section, a first terminal has the same potential as the gate wiring, a second terminal has the same potential as the source wiring, The terminal 2 and the third terminal of the same potential as the capacitance wiring are arranged in a row. The number of terminals may be any number and may be determined appropriately by the implementer.

[0158] In this way, six photolithography steps were performed using six photomasks to create the bottom. A second thin film transistor 170 which is a gate-type n-channel thin film transistor; Then, these are arranged in a matrix to correspond to each pixel. To fabricate an active matrix display device by arranging the layers to form a pixel section. For the sake of convenience, this specification refers to such a substrate as the active matrix. This is called a risk board.

[0159] In addition, when the same material as the pixel electrode is used to electrically connect to the gate line, The third photolithography step can be omitted, so the process is reduced to five photolithography steps. Using five photomasks, a bottom-gate n-channel thin-film transistor was fabricated. A second thin film transistor, which is a storage capacitor, can be completed.

[0160] In addition, when the material of the second gate electrode is made different from the material of the pixel electrode as shown in FIG. In this case, one photolithography step is added, and one photomask is added.

[0161] When manufacturing an active matrix type liquid crystal display device, an active matrix substrate A liquid crystal layer is provided between the active matrix substrate and a counter substrate having a counter electrode. The counter electrode is fixed to the counter substrate. A fourth terminal electrically connected to the common electrode is provided on the active matrix substrate. This fourth terminal is used to set the common electrode to a fixed potential, such as GND or 0V. This is a terminal for

[0162] In addition, the pixel configuration is not limited to that shown in FIG. 14, and an example of a top view different from that shown in FIG. 14 is shown in FIG. In the case of 16, no capacitance wiring is provided, and the pixel electrode is connected to the gate wiring, the protective insulating film, and the gate In this example, a storage capacitor is formed by stacking the capacitor wiring and the capacitor wiring The third terminal connected to the terminal 3 can be omitted. The same reference numerals will be used for the explanation.

[0163] In an active matrix type liquid crystal display device, pixel electrodes arranged in a matrix form By driving the selected pixels, a display pattern is formed on the screen. A voltage is applied between the electrode and the counter electrode corresponding to the pixel electrode. The liquid crystal layer disposed between the pixel electrode and the counter electrode is optically modulated, and this optical modulation produces a display pattern. is perceived by the observer as

[0164] When displaying moving images on a liquid crystal display device, the response of the liquid crystal molecules themselves is slow, resulting in image retention. In order to improve the moving image characteristics of the LCD device, There is a driving technique called black insertion, which displays black every other frame.

[0165] In addition, the vertical period is increased by 1.5 or 2 times to improve the video characteristics. A driving technique called double speed driving may be used.

[0166] In addition, in order to improve the video characteristics of liquid crystal display devices, multiple LEDs (light emitting diodes) are used as backlights. A surface light source is formed by using a diode) light source or multiple EL light sources, etc., and a surface light source is formed. There is also a driving technology that drives each light source to light intermittently within one frame period. In addition, three or more types of LEDs may be used, or white-emitting LEDs may be used. Since multiple LEDs can be controlled, the LE can be switched according to the timing of the optical modulation of the liquid crystal layer. The timing of the LEDs can also be synchronized. This is particularly useful when displaying images with a large proportion of black areas occupying the entire screen. This has the effect of reducing power consumption.

[0167] By combining these driving technologies, the display characteristics such as the video characteristics of the LCD device can be improved. can be improved compared to the conventional method.

[0168] The n-channel transistor obtained in this embodiment is an In-Ga-Zn-O based non-single crystal The crystal film is used in the channel formation region and has good dynamic characteristics, so these driving technologies Can be combined.

[0169] In addition, when a light-emitting display device is manufactured, one electrode (also called a cathode) of the organic light-emitting element is In order to set the low power supply potential, for example GND or 0V, the cathode is connected to the terminal. A fourth terminal is provided for setting the voltage level, for example, GND, 0V, etc. When manufacturing a device, a power supply line is provided in addition to a source line and a gate line. Therefore, the terminal section is provided with a fifth terminal that is electrically connected to the power supply line.

[0170] The gate line driver circuit or source line driver circuit is formed of a thin film transistor using an oxide semiconductor. By forming a thin film transistor using a driving circuit, the manufacturing cost can be reduced. By directly connecting the gate electrode and the source wiring or the drain wiring, a contact hole is formed. It is possible to provide a display device capable of reducing the number of driving circuits and reducing the area occupied by the driving circuits.

[0171] Therefore, according to this embodiment, a display device with excellent electrical characteristics can be provided at low cost. do.

[0172] This embodiment mode can be freely combined with the first, second, or third embodiment mode. It can be adjusted.

[0173] (Embodiment 5) In this embodiment mode, an example of an electronic paper is shown as a semiconductor device.

[0174] FIG. 17 shows an active matrix type electronic device as an example of a semiconductor device other than a liquid crystal display device. The thin film transistor 581 used in the pixel portion of the semiconductor device is It can be fabricated in the same manner as the thin film transistor of the pixel part shown in Form 4. The thin film transistor includes a single crystal film as a semiconductor layer. As shown in the figure, the pixel section and the driver circuit can be fabricated on the same substrate, reducing manufacturing costs. Paper can be realized.

[0175] The electronic paper in FIG. 17 is an example of a display device that uses the twisting ball display method. The ball display method is an electrode layer that uses spherical particles painted in black and white as display elements. A potential difference is applied between the first electrode layer and the second electrode layer. This is a method of displaying by controlling the orientation of spherical particles that are generated.

[0176] The thin film transistor 581 is a thin film transistor having a bottom gate structure, and the source electrode layer The drain electrode layer is formed on the first electrode layer 587 and the insulating layers 583, 584, and 585. The first electrode layer 587 and the second electrode layer 588 are in contact with each other at the opening and are electrically connected. The liquid-filled container has a black area 590a and a white area 590b in between. A spherical particle 589 including a particle size 594 is provided between a pair of substrates 580 and 596. The spherical particle 589 is filled with a filler 595 such as a resin (see FIG. 17).

[0177] Also, instead of the twist ball, an electrophoretic element can be used. and a 10μm to 20μm diameter nanoparticle that contains positively charged white nanoparticles and negatively charged black nanoparticles. Microcapsules with a diameter of about 0 μm are used. When an electric field is applied to the microcapsules by the first and second electrode layers, the microcapsules emit white light. White particles and black particles move in opposite directions, allowing the display to be white or black. A display element that applies this principle is an electrophoretic display element, known as electronic paper. Dynamic display elements have a higher reflectivity than liquid crystal display elements, so auxiliary lights are not required. It consumes little power and the display can be seen even in dimly lit places. Even if the power supply is cut off, the image once displayed can be retained. From the radio wave source to a semiconductor device with a display function (simply a display device, or a semiconductor device equipped with a display device) It is possible to store the displayed image even if the device (also called a "photography device") is moved away. do.

[0178] Through the above steps, electronic paper can be manufactured as a semiconductor device at reduced manufacturing costs. can be done.

[0179] This embodiment may be appropriately combined with the configuration described in the first or second embodiment. It is possible to implement.

[0180] (Embodiment 6) In this embodiment mode, a light-emitting display device is shown as an example of a semiconductor device. Here, a light-emitting element that uses electroluminescence is used as the element. Light-emitting devices that utilize fluoroluminescence are characterized by the fact that the luminescent material is either an organic compound or an inorganic compound. Generally, the former are called organic EL elements and the latter are called inorganic EL elements. It's been discovered.

[0181] In an organic EL element, electrons and holes are released from a pair of electrodes by applying a voltage to the light-emitting element. are injected into layers containing light-emitting organic compounds, causing a current to flow. The rears (electrons and holes) recombine to form an excited state in the light-emitting organic compound. When the excited state returns to the ground state, light is emitted. Such a light-emitting element is called a current-excitation type light-emitting element.

[0182] Inorganic EL elements are divided into dispersion-type inorganic EL elements and thin-film-type inorganic EL elements according to their element structure. Dispersion-type inorganic EL elements have a light-emitting layer in which particles of a light-emitting material are dispersed in a binder. The emission mechanism is a donor-acceptor reaction that utilizes the donor and acceptor levels. Thin-film inorganic EL elements are made by sandwiching a light-emitting layer between dielectric layers. The structure is sandwiched between electrodes, and the light emission mechanism utilizes the inner shell electron transition of metal ions. In this example, the light-emitting element is an organic EL element. do.

[0183] FIG. 18 shows an example of a pixel configuration to which digital time gray scale driving can be applied as an example of a semiconductor device. This is a diagram.

[0184] The configuration of a pixel to which digital time gray scale driving can be applied and the operation of the pixel will be described. The channel formation region is made of an oxide semiconductor layer (In-Ga-Zn-O non-single crystal film). 1 shows an example in which two L-channel transistors are used in one pixel.

[0185] The pixel 6400 includes a switching transistor 6401, a driving transistor 6402, The switching transistor 64 has a light emitting element 6404 and a capacitor element 6403. 01 has a gate connected to a scanning line 6406 and a first electrode (one of the source and drain electrodes) The first electrode (the other of the source electrode and the drain electrode) is connected to a signal line 6405, and the second electrode (the other of the source electrode and the drain electrode) is connected to a drive The driving transistor 6402 is connected to the gate of the driving transistor 6402. The gate is connected to a power supply line 6407 via a capacitor element 6403, and the first electrode is connected to a power supply line 640 7, and the second electrode is connected to the first electrode (pixel electrode) of the light emitting element 6404. The second electrode of the light emitting element 6404 corresponds to a common electrode 6408 .

[0186] A low power supply potential is set to the second electrode (common electrode 6408) of the light emitting element 6404. Note that the low power supply potential is a low power supply potential with respect to the high power supply potential set to the power supply line 6407. Potential < High power supply potential. For example, GND, 0V, etc. are set as low power supply potential. The potential difference between the high power supply potential and the low power supply potential is applied to the light emitting element 6404. In order to make the light emitting element 6404 emit light by passing a current through the light emitting element 6404, a high power supply potential and the low power supply potential is set to be equal to or higher than the forward threshold voltage of the light emitting element 6404. Each potential is set.

[0187] The capacitor 6403 is omitted by substituting the gate capacitance of the driving transistor 6402. It is also possible to set the gate capacitance of the driving transistor 6402 as follows: A capacitance may be formed between the gate electrode and the second electrode.

[0188] In the case of a voltage input voltage driving method, the gate of the driving transistor 6402 is The driving transistor 6402 is in two states, either fully on or fully off. A video signal is inputted, that is, the driving transistor 6402 is operated in a linear region. In order to operate the driving transistor 6402 in a linear region, the voltage of the power supply line 6407 must be higher than that of the driving transistor 6402. A high voltage is applied to the gate of the driving transistor 6402. A voltage equal to or higher than (power supply line voltage + Vth of the driving transistor 6402) is applied.

[0189] In addition, when analog gray scale driving is performed instead of digital time gray scale driving, the input of the signal is different. By doing so, the same pixel configuration as in FIG. 18 can be used.

[0190] In the case of performing analog gradation driving, a light emitting element 6404 is connected to the gate of a driving transistor 6402. A voltage equal to or higher than the forward voltage of the light emitting element 6401 and the Vth of the driving transistor 6402 is applied. The forward voltage in 04 refers to the voltage required to achieve the desired brightness, and should be at least 100% forward voltage. In addition, the video transistor 6402 is designed to operate in the saturation region. By inputting an optical signal, a current can be passed through the light emitting element 6404. In order to operate the transistor 6402 in the saturation region, the potential of the power supply line 6407 is The gate potential of the light emitting element 6402 is set higher than that of the gate of the transistor 6403. Analog gradation drive can be performed by passing a current corresponding to a video signal through 6404.

[0191] Note that the pixel configuration shown in FIG. 18 is not limited to this. For example, A switch, a resistive element, a capacitive element, a transistor, a logic circuit, or the like may be added.

[0192] Next, the structure of the light emitting element will be described with reference to FIG. 19(A), FIG. 19(B), and FIG. 19(C). Here, the case where the driving TFT is the thin film transistor 170 shown in FIG. The cross-sectional structure of a pixel will be described with reference to FIG. 19(A), FIG. 19(B), and FIG. The TFTs 7001, 7011, and 7021, which are driving TFTs used in the semiconductor device of The thin film transistor 170 can be manufactured in the same manner as in the first embodiment. The thin film transistor has excellent electrical characteristics and includes a non-single crystal film based on ZnO as a semiconductor layer.

[0193] The light emitting element only needs to have at least one of the anode and cathode transparent in order to extract light. Then, a thin film transistor and a light emitting element are formed on the substrate, and light is taken from the surface opposite to the substrate. Top emission, bottom emission, and side emission. There are light-emitting elements with a double-sided emission structure in which light is emitted from the side of the pixel. The present invention can also be applied to a light emitting element having an injection structure.

[0194] A light emitting element having a top emission structure will be described with reference to FIG.

[0195] In FIG. 19(A), the driving TFT TFT7001 is a thin-film transistor shown in FIG. When the light emitted from the light emitting element 7002 passes through the anode 7005 side, A cross-sectional view of a pixel is shown in FIG. 19(A). In FIG. 19(A), a cathode 7003 of a light-emitting element 7002 and a driving TF A TFT 7001 is electrically connected to a cathode 7003, and a light-emitting layer 7004 is formed on the cathode 7003. The anode 7005 is laminated in this order. The cathode 7003 has a small work function and reflects light. Various materials can be used as long as they are conductive films that reflect light. For example, Ca, Al, CaF, The light-emitting layer 7004 is preferably made of a single layer. The laminate may be made of a single layer or a plurality of layers. In this case, an electron injection layer, an electron transport layer, a light emitting layer, a hole transport layer, and a hole The anode 7005 is a light-transmitting layer. The insulating layer is formed using a conductive material having a light-transmitting property, for example, indium oxide containing tungsten oxide. Indium oxide, indium zinc oxide with tungsten oxide, indium zinc oxide with titanium oxide Indium tin oxide (ITO) ), indium zinc oxide, indium tin oxide doped with silicon oxide, etc. Alternatively, a conductive film having a conductive property may be used.

[0196] The region where the light-emitting layer 7004 is sandwiched between the cathode 7003 and the anode 7005 constitutes the light-emitting element 7002. In the case of the pixel shown in FIG. 19(A), the light emitted from the light emitting element 7002 is The light is emitted toward the anode 7005 as indicated by the mark.

[0197] Note that a second gate electrode provided over the oxide semiconductor layer in the driver circuit is a cathode 7003. It is preferable to form them from the same material since this simplifies the process.

[0198] Next, a light emitting element having a bottom emission structure will be described with reference to FIG. 011 is the thin film transistor 170 shown in FIG. 1A, and the light emitting element 7012 emits light. FIG. 19B shows a cross-sectional view of a pixel in the case where the light emitted from the driving A light-emitting element is formed on a light-transmitting conductive film 7017 electrically connected to the moving TFT 7011. A cathode 7013 of 7012 is formed, and a light-emitting layer 7014 and an anode 70 In addition, when the anode 7015 is transparent, the anode 7015 is covered with the insulating film 15. As shown in FIG. 1, a shielding film 7016 for reflecting or shielding light may be formed. As in the case of FIG. 19(A), various conductive materials with small work functions can be used. However, the thickness of the film should be such that it transmits light (preferably 5 nm to 3 For example, an aluminum film having a thickness of 20 nm is used as the cathode 7013. The light-emitting layer 7014 can be a single layer, as in FIG. The anode may be configured as a single layer or as a laminate of multiple layers. 7015 does not need to transmit light, but as in FIG. 19(A), it is a conductive material having light-transmitting properties. The shielding film 7016 can be formed of, for example, a light-reflecting metal or the like. However, it is not limited to a metal film. For example, a resin containing a black pigment may be used. You can also be there.

[0199] The region where the light-emitting layer 7014 is sandwiched between the cathode 7013 and the anode 7015 is the light-emitting element 7012. In the case of the pixel shown in FIG. 19B, the light emitted from the light-emitting element 7012 corresponds to The light is emitted toward the cathode 7013 as shown by the arrow.

[0200] Note that a second gate electrode provided over the oxide semiconductor layer in the driver circuit is a cathode 7013. It is preferable to form them from the same material since this simplifies the process.

[0201] Next, a light emitting element having a dual emission structure will be described with reference to FIG. In this example, a conductive film 7027 having a light-transmitting property and electrically connected to the driving TFT 7021 is formed on the substrate 7022. A cathode 7023 of the light-emitting element 7022 is formed, and a light-emitting layer 7024 is formed on the cathode 7023. The anode 7025 is laminated in order. The cathode 7023 is, as in the case of FIG. Various conductive materials with small thermal coefficients can be used. However, the thickness of the material should be For example, the cathode 7023 is made of Al having a thickness of 20 nm. The light-emitting layer 7024 can be formed of a single layer, as in FIG. The anode 70 may be configured as a single layer or as a laminate of multiple layers. 25 is formed using a conductive material having a light transmitting property, similar to FIG. It is possible.

[0202] The overlapping portion of the cathode 7023, the light-emitting layer 7024, and the anode 7025 constitutes the light-emitting element 70. In the case of the pixel shown in FIG. 19C, the light emitted from the light emitting element 7022 is is emitted toward both the anode 7025 side and the cathode 7023 side as indicated by the arrows.

[0203] Note that the second gate electrode provided over the oxide semiconductor layer in the driver circuit is a conductive film 7027 It is preferable to form the gate electrode from the same material as the gate electrode because the process can be simplified. The second gate electrode provided on the semiconductor layer is made of the same material as the conductive film 7027 and the cathode 7023. By stacking using this method, the process can be simplified and the wiring resistance can be reduced. This can be preferably reduced.

[0204] Although the organic EL element has been described as the light-emitting element here, inorganic EL elements can also be used as the light-emitting element. It is also possible to provide an L element.

[0205] In this embodiment, a thin film transistor (driving TFT) that controls driving of a light emitting element is Although an example in which the light-emitting element is electrically connected has been shown, the current between the driving TFT and the light-emitting element is A control TFT may be connected.

[0206] The semiconductor device described in this embodiment mode has a structure shown in FIG. The present invention is not limited to the above-described configuration, and various modifications based on the disclosed technical concept are possible. do.

[0207] Next, a top surface of a light-emitting display panel (also called a light-emitting panel) which corresponds to one embodiment of a semiconductor device and The cross section will be described with reference to Fig. 20(A) and Fig. 20(B). Fig. 20(A) shows the first The thin film transistor and the light emitting element formed on the substrate are sandwiched between the substrate and the second substrate by a sealant. FIG. 20(B) is a top view of the panel sealed by the HI in FIG. 20(A). This corresponds to a cross-sectional view.

[0208] A pixel portion 4502, a signal line driver circuit 4503a, and a signal line driver circuit 4504 are provided on a first substrate 4501. A sealant 4505 is formed so as to surround the scanning line driver circuits 4504a and 4504b. In addition, a pixel portion 4502, signal line driver circuits 4503a and 4503b, and A second substrate 4506 is provided on the scanning line driver circuits 4504a and 4504b. The pixel portion 4502, the signal line driver circuits 4503a and 4503b, and the scanning line driver circuit 45 4504a and 4504b are a first substrate 4501, a sealant 4505, and a second substrate 4506. The filling material 4507 is sealed with the sealing material 4507. Highly sealed protective film with little outgassing (lamination film, UV curable resin film) It is preferable to package (enclose) the package in a material such as a film or a cover material.

[0209] A pixel portion 4502, a signal line driver circuit 4503a, and a fourth 503b and the scanning line driver circuits 4504a and 4504b each have a plurality of thin film transistors. In FIG. 20B, a thin film transistor 4510 included in a pixel portion 4502 and a signal 45, a thin film transistor 4509 included in a line driver circuit 4503a is illustrated.

[0210] The thin film transistors 4509 and 4510 are made of In-Ga-Zn-O non-single crystal films as semiconductor layers. As a result, the highly reliable thin film transistor described in Embodiment 1 can be applied. In addition, the thin film transistor 4509 is a thin film transistor having a semiconductor layer as shown in Embodiment 1 and FIG. The gate electrodes are disposed above and below the gate electrode.

[0211] In addition, 4511 corresponds to a light-emitting element, and a first electrode which is a pixel electrode of the light-emitting element 4511 is The layer 4517 is electrically connected to the source electrode layer or the drain electrode layer of the thin film transistor 4510. The light-emitting element 4511 is configured as a first electrode layer 4517, an electroluminescent layer The first electrode layer 4512 and the second electrode layer 4513 are stacked in a stacked structure. The light emitting element 4511 is not rotated in accordance with the direction of the light to be extracted from the light emitting element 4511. The configuration can be changed as appropriate.

[0212] The partition 4520 is formed using an organic resin film, an inorganic insulating film, or an organic polysiloxane. In particular, a photosensitive material is used to form an opening on the first electrode layer 4517, and the sidewall of the opening It is preferable that the inclined surface is formed so as to have a continuous curvature.

[0213] The electroluminescent layer 4512 may be composed of a single layer or a plurality of layers may be laminated. It doesn't matter whether it is done or not.

[0214] In order to prevent oxygen, hydrogen, moisture, carbon dioxide, and the like from entering the light-emitting element 4511, the second electrode layer A protective film may be formed on the partition wall 4513 and the partition wall 4520. The protective film may be a silicon nitride film, A silicon oxynitride film, DLC film, etc. can be formed.

[0215] In addition, signal line driver circuits 4503a and 4503b, scanning line driver circuits 4504a and 4504b Various signals and potentials applied to the pixel portion 4502 are It is supplied by b.

[0216] In this embodiment, the connection terminal electrode 4515 is connected to the first electrode layer 4 of the light emitting element 4511. The terminal electrode 4516 is formed from the same conductive film as the thin film transistors 4509 and 517. The source electrode layer and the drain electrode layer 510 are formed from the same conductive film.

[0217] The connection terminal electrode 4515 is connected to the terminal of the FPC 4518a via the anisotropic conductive film 4519. The electrodes are electrically connected to each other.

[0218] The second substrate 4506 located in the direction in which light is extracted from the light emitting element 4511 must be transparent. In this case, a glass plate, a plastic plate, a polyester film or A light-transmitting material such as an acrylic film is used.

[0219] In addition, filler 4507 can be inert gas such as nitrogen or argon, or ultraviolet-curing resin. It can be made of oil or thermosetting resin, and can be made of PVC (polyvinyl chloride), acrylic, Polyimide, epoxy resin, silicone resin, PVB (polyvinyl butyral) or EVA (ethylene vinyl acetate) can be used.

[0220] If necessary, a polarizing plate or a circular polarizing plate (including an elliptical polarizing plate) may be provided on the light-emitting surface of the light-emitting element. Optical films such as retardation plates (λ / 4 plates, λ / 2 plates) and color filters may be provided as appropriate. In addition, the polarizing plate or the circular polarizing plate may be provided with an anti-reflection film. Anti-glare treatment can be applied to diffuse reflected light and reduce glare.

[0221] The signal line driver circuits 4503a and 4503b and the scanning line driver circuits 4504a and 4504b are A single crystal semiconductor film or a polycrystalline semiconductor film is formed on a separately prepared single crystal semiconductor substrate or an insulating substrate. Alternatively, the signal line driver circuit may be implemented as a driver circuit formed by a thin film. Alternatively, only a part of the scanning line driver circuit or only a part of the scanning line driver circuit may be formed separately and mounted. This embodiment is not limited to the configurations of FIGS. 20(A) and 20(B).

[0222] By the above steps, a light-emitting display device (display panel) can be manufactured at reduced manufacturing costs. can.

[0223] This embodiment may be appropriately combined with the configuration described in the first or second embodiment. It is possible to implement.

[0224] (Embodiment 7) In this embodiment mode, a top view and a cross section of a liquid crystal display panel, which is one mode of a semiconductor device, will be described. This will be explained with reference to Figs. 21(A1), 21(A2) and 21(B). Fig. 21(A1) 21A2 shows the In-GaAs layer shown in the first embodiment formed on a first substrate 4001. Thin film transistors 4010 and 4011 including a-Zn-O based non-single crystal film as a semiconductor layer; The liquid crystal element 4013 is sealed between the second substrate 4006 and the liquid crystal element 4013 by a sealant 4005. FIG. 21(B) is a top view of the panel, and FIG. 21(A1) is a top view of the panel. This corresponds to the cross-sectional view in FIG.

[0225] A pixel portion 4002 and a scanning line driver circuit 4004 are provided on a first substrate 4001. In this manner, a sealant 4005 is provided. A second substrate 4006 is provided on the path 4004. The line driver circuit 4004 is made up of a first substrate 4001, a sealant 4005, and a second substrate 4006. The liquid crystal layer 4008 is sealed together with the first substrate 4001. In a region different from the region surrounded by the material 4005, a single crystal is formed on a separately prepared substrate. A signal line driver circuit 4003 formed of a semiconductor film or a polycrystalline semiconductor film is mounted.

[0226] The method of connecting the separately formed drive circuit is not particularly limited, and may be a COG method, A wire bonding method, a TAB method, or the like can be used. FIG. 21A shows an example of mounting a signal line driver circuit 4003 by the COG method. This is an example in which a signal line driver circuit 4003 is mounted by the TAB method.

[0227] A pixel portion 4002 and a scanning line driver circuit 4004 are provided on a first substrate 4001. In FIG. 21B, the thin film transistor included in the pixel portion 4002 is A transistor 4010 and a thin film transistor 4011 included in the scanning line driver circuit 4004 Insulating layers 4020 and 4021 are formed on the thin film transistors 4010 and 4011. 1 is provided.

[0228] The thin film transistors 4010 and 4011 are made of In-Ga-Zn-O non-single crystal films as semiconductor layers. The thin film transistor described in Embodiment 1 can be used as the thin film transistor. The transistor 4011 is a thin-film transistor having a back gate electrode shown in FIG. 2(A) of the second embodiment. Equivalent to a transistor.

[0229] In addition, a pixel electrode layer 4030 of the liquid crystal element 4013 is connected to the thin film transistor 4010. The counter electrode layer 4031 of the liquid crystal element 4013 is electrically connected to the second substrate 40. 06. A pixel electrode layer 4030, a counter electrode layer 4031, and a liquid crystal layer 4008 are formed on the liquid crystal layer 4006. The overlapping portion corresponds to a liquid crystal element 4013. The electrode layer 4031 is provided with insulating layers 4032 and 4033 which function as alignment films. A liquid crystal layer 4008 is sandwiched between insulating layers 4032 and 4033 .

[0230] The first substrate 4001 and the second substrate 4006 may be made of glass or metal (typically, stainless steel). Stainless steel, ceramics, and plastics can be used. , FRP (Fiberglass-Reinforced Plastics) board, PV F (polyvinyl fluoride) film, polyester film or acrylic resin film Alternatively, you can use aluminum foil with a PVF film or polyester film. A sheet having a structure sandwiched between films can also be used.

[0231] Also, 4035 is a columnar spacer obtained by selectively etching the insulating film. In order to control the distance (cell gap) between the pixel electrode layer 4030 and the counter electrode layer 4031 A spherical spacer may be used. is electrically connected to a common potential line provided on the same substrate as the thin film transistor 4010. The common connection portion is used to connect the counter electrode layer 40 to the conductive particles disposed between the pair of substrates. The conductive particles can electrically connect the sealing material 40 to the common potential line. Included in 05.

[0232] Alternatively, a liquid crystal that exhibits a blue phase without using an alignment film may be used. The blue phase is one of the liquid crystal phases. When the temperature of cholesteric liquid crystal is increased, the phase immediately transitions from the cholesteric phase to the isotropic phase. The blue phase appears only in a narrow temperature range, so it is necessary to improve the temperature range. In order to achieve this, a liquid crystal composition containing 5% by weight or more of a chiral agent is used for the liquid crystal layer 4008. A liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent has a response speed of 10 μs to It is short at 100μs, has optical isotropy so no alignment treatment is required, and has small viewing angle dependency. stomach.

[0233] Although the present embodiment is an example of a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device may also be used. It can also be applied to a liquid crystal display device.

[0234] In the liquid crystal display device of the present embodiment, a polarizing plate is provided on the outer side (the viewing side) of the substrate, and In this example, the color layer and the electrode layer used for the display element are provided in that order, but the polarizing plate is provided on the inner side of the substrate. In addition, the laminated structure of the polarizing plate and the colored layer is not limited to that of the present embodiment. The color layer may be appropriately selected depending on the material and manufacturing process conditions of the color layer. A light-shielding film that functions as a light-shielding film may be provided.

[0235] In this embodiment, in order to reduce the surface unevenness of the thin film transistor, In order to improve the reliability of the transistor, the thin film transistor obtained in the first embodiment is provided with a protective film or The insulating layer 4020 and the insulating layer 4021 function as a planarizing insulating film. The protective film is designed to prevent contamination by organic matter, metals, water vapor, and other contaminants suspended in the air. The protective film is formed by sputtering. Silicon oxide film, silicon nitride film, silicon oxynitride film, silicon nitride oxide film, aluminum oxide film, nitride A single layer or multilayer of an aluminum film, an aluminum oxynitride film, or an aluminum nitride oxide film. In this embodiment, an example in which the protective film is formed by sputtering is shown. The method is not limited to the above, and may be a PCVD method or other method. This protective film functions as a second gate insulating layer, and a back gate is formed on the second gate insulating layer. The semiconductor device includes a thin film transistor having a

[0236] Here, an insulating layer 4020 having a laminated structure is formed as a protective film. A silicon oxide film is formed by sputtering as the first layer of the 0. Silicon oxide film as a protective film By using the above, it is possible to prevent hillocks in the aluminum film used as the source electrode layer and the drain electrode layer. It is effective in stopping.

[0237] In addition, an insulating layer is formed as the second layer of the protective film. A silicon nitride film is formed by sputtering. Prevents ions such as thorium from penetrating the semiconductor region and changing the electrical characteristics of the TFT. It can be controlled.

[0238] After forming the protective film, the semiconductor layer may be annealed (at 300° C. to 400° C.). In addition, the back gate is formed after the protective film is formed.

[0239] In addition, an insulating layer 4021 is formed as a planarization insulating film. Heat-resistant organic compounds such as amide, acrylic, benzocyclobutene, polyamide, and epoxy. In addition to the above organic materials, low-k materials can be used. , siloxane resin, PSG (phosphorus glass), BPSG (borophosphorus glass), etc. are used. In addition, by stacking a plurality of insulating films made of these materials, an insulating layer can be formed. 4021 may be formed.

[0240] Siloxane-based resin is a type of Si-OS formed using siloxane-based materials as starting materials. The siloxane resin corresponds to a resin containing an i bond. Alternatively, the organic group may have a fluoro group. That's fine.

[0241] The method for forming the insulating layer 4021 is not particularly limited, and may be a sputtering method, an SOG method, or the like, depending on the material. , spin coating, dip coating, spray coating, droplet ejection method (inkjet method, screen printing, offset printing, etc.), doctor knife, roll coater, curtain coater, knife When the insulating layer 4021 is formed using a material liquid, In the step of bonding, the semiconductor layer may be annealed (at 300° C. to 400° C.) at the same time. By combining the firing process of the edge layer 4021 with the annealing process of the semiconductor layer, a semiconductor device can be efficiently manufactured. It becomes possible to do so.

[0242] The pixel electrode layer 4030 and the counter electrode layer 4031 are made of indium oxide containing tungsten oxide. , indium zinc oxide with tungsten oxide, indium oxide with titanium oxide, Indium tin oxide containing titanium oxide, indium tin oxide (hereinafter referred to as ITO), Translucent materials such as indium zinc oxide and indium tin oxide doped with silicon oxide A conductive material may be used.

[0243] The pixel electrode layer 4030 and the counter electrode layer 4031 are made of a conductive polymer. The conductive composition may be used to form the conductive film. The pixel electrode thus fabricated has a sheet resistance of 10,000 Ω / □ or less and a light transmittance of 550 nm. It is preferable that the resistance of the conductive polymer contained in the conductive composition is 70% or more. It is preferable that the electrical conductivity be 0.1 Ω·cm or less.

[0244] As the conductive polymer, a so-called π-electron conjugated conductive polymer can be used. For example, polyaniline or its derivatives, polypyrrole or its derivatives, polythiophene or or a derivative thereof, or a copolymer of two or more of these.

[0245] A signal line driver circuit 4003 and a scanning line driver circuit 4004 or a pixel section 4 Various signals and potentials are applied to 002 via FPC4018.

[0246] In this embodiment, the connection terminal electrode 4015 is connected to the pixel electrode layer 40 of the liquid crystal element 4013. The terminal electrode 4016 is formed from the same conductive film as the thin film transistors 4010 and 30. The source electrode layer and the drain electrode layer 11 are formed of the same conductive film.

[0247] The connection terminal electrode 4015 is connected to a terminal of the FPC 4018 via an anisotropic conductive film 4019. The electrodes are electrically connected to each other.

[0248] In addition, in FIG. 21(A1) and FIG. 21(A2), a signal line driver circuit 4003 is formed separately. 10, an example in which the first substrate 4001 is mounted is shown, but this embodiment is not limited to this configuration. The scanning line driver circuit may be formed separately and mounted, or may be mounted as a part of the signal line driver circuit or Alternatively, only a part of the scanning line driver circuit may be formed separately and mounted.

[0249] FIG. 22 shows a liquid crystal display module formed as a semiconductor device using a TFT substrate 2600. An example is shown.

[0250] FIG. 22 shows an example of a liquid crystal display module, in which a TFT substrate 2600 and an opposing substrate 2601 are connected. The substrate 2602 is fixed to the substrate 2601 by a bonding material 2602, and a pixel portion 2603 including a TFT and the like and a liquid crystal layer are disposed between the substrate 2601 and the substrate 2602. A display element 2604 and a colored layer 2605 are provided to form a display area. is necessary for color display, and in the case of the RGB method, it corresponds to each color of red, green, and blue. A colored layer is provided corresponding to each pixel. On the outside, a polarizing plate 2606, a polarizing plate 2607, and a diffusion plate 2613 are arranged. It is composed of a cathode ray tube 2610 and a reflector 2611, and a circuit board 2612 is a flexible wiring board. A wiring board 2609 is connected to the wiring circuit section 2608 of the TFT board 2600, and the controller The LCD has external circuits such as a filter circuit and a power supply circuit. The layers may be laminated with a retardation plate interposed therebetween.

[0251] The LCD module is available in TN (Twisted Nematic) mode, IPS (In-plane Switching) mode, n-Plane-Switching mode, FFS (Fringe Field Switching) switching mode, MVA (Multi-domain Vertical A alignment) mode, PVA(Patterned Vertical Alignment) mode nment), ASM(Axially Symmetric aligned Mic) ro-cell) mode, OCB(Optical Compensated Bire) fringence mode, FLC (Ferroelectric Liquid C rystal) mode, AFLC (AntiFerroelectric Liquid Crystal) can be used.

[0252] By the above steps, a liquid crystal display panel can be manufactured as a semiconductor device at reduced manufacturing costs. This can be done.

[0253] This embodiment is similar to the configuration described in the first, second, or third embodiment. It is possible to carry out any suitable combination.

[0254] (Embodiment 8) The semiconductor device according to the disclosed invention can be applied to various electronic devices (including gaming machines). The electronic device can be, for example, a television device (television or television (also called digital receivers), computer monitors, digital cameras, digital video cameras, etc. digital photo frames, mobile phones (also called mobile phones or mobile phone devices), These include large game machines such as small game machines, portable information terminals, audio playback devices, and pachinko machines. can be.

[0255] FIG. 23A shows an example of a mobile information terminal device 9200. The 00 has a built-in computer and is capable of performing various data processing operations. Such a portable information terminal device 9200 includes a PDA (Personal Digital Audio Player). Assistance).

[0256] The mobile information terminal device 9200 is composed of two housings, a housing 9201 and a housing 9203. The housing 9201 and the housing 9203 are connected to each other at a connecting portion 9207 so as to be foldable. A display unit 9202 is incorporated in a housing 9201, and a keyboard 9203 is incorporated in a housing 9203. Of course, the configuration of the mobile information terminal device 9200 is not limited to the above. It is sufficient that the device has a structure including at least a thin film transistor having a back gate electrode. The driver circuit and the other auxiliary equipment can be mounted on the same board. By forming a pixel section, manufacturing costs are reduced, and thin film transistors with high electrical characteristics can be used. It is possible to realize a portable information terminal device having the above-mentioned configuration.

[0257] FIG. 23B shows an example of a digital video camera 9500. The Mela 9500 has a display unit 9503 built into a housing 9501, and various operation units are also installed. The configuration of the digital video camera 9500 is not particularly limited. Any other auxiliary equipment may be used as long as the device is provided with a thin film transistor having a back gate electrode. The driving circuit and the pixel portion are formed on the same substrate. This reduces manufacturing costs, and digital video has thin-film transistors with high electrical characteristics. It is possible to realize a video camera.

[0258] FIG. 23C shows an example of a mobile phone 9100. The mobile phone 9100 has a housing It is composed of two housings, 9102 and housing 9101, and is foldable by connecting part 9103. The display unit 9104 is incorporated in the housing 9102. The body 9101 is provided with an operation key 9106. The mobile phone 9100 is configured as follows: There is no particular limitation, but the configuration includes at least a thin film transistor having a back gate electrode. Other auxiliary equipment may be provided as appropriate. By forming the operating circuit and pixel section, the manufacturing cost is reduced, and thin film transistors with high electrical properties are used. It is possible to realize a mobile phone having a register.

[0259] FIG. 23D shows an example of a portable computer 9300. The electronic device 300 includes a housing 9301 and a housing 9302 that are connected so as to be openable and closable. A display unit 9303 is built into the housing 9302, and a keyboard 9304 and the like are provided in the housing 9302. The configuration of the computer 9300 is not particularly limited, and at least a back gate electrode Any configuration is acceptable as long as the device is equipped with a thin film transistor having the above structure, and other auxiliary equipment is appropriately provided. The manufacturing cost can be reduced by forming the driver circuit and the pixel portion on the same substrate. This makes it possible to realize a computer having thin film transistors with reduced noise and excellent electrical properties.

[0260] FIG. 24A shows an example of a television device 9600. The display unit 9603 is incorporated in the housing 9601. In addition, the stand 9605 supports the housing 9601. This shows a configuration in which the above is supported.

[0261] The television device 9600 can be operated using an operation switch on the housing 9601 or a separate remote control. This can be done by the remote control operation device 9610. The channel and volume can be controlled by the 9609, and the display 9603 shows In addition, the remote control unit 9610 can control the video. A display portion 9607 for displaying information output from 9610 may be provided.

[0262] The television device 9600 includes a receiver and a modem. It can receive more general television broadcasts, and can also be connected to a modem via wired or wireless connection. By connecting to a network, communication can be one-way (sender to receiver) or two-way. It is also possible to communicate information (between a sender and a receiver, or between receivers).

[0263] FIG. 24B shows an example of a digital photo frame 9700. The photo frame 9700 includes a display unit 9703 built into a housing 9701. The unit 9703 is capable of displaying various images, for example images captured by a digital camera. By displaying the image data, it can function like a normal photo frame.

[0264] The Digital Photo Frame 9700 is equipped with an operation unit, external connection terminals (USB terminal, US A terminal that can be connected to various cables such as B cable, etc., and a recording medium insertion section, etc. These components may be installed on the same surface as the display unit, but they may be installed on the side or back. It is preferable to have a digital photo frame with a built-in memory card because it improves the design. A memory that stores image data taken with a digital camera is inserted into the body insertion section. The captured image data can be displayed on the display portion 9703 .

[0265] The digital photo frame 9700 may also be configured to transmit and receive information wirelessly. It is also possible to wirelessly import and display desired image data.

[0266] FIG. 25(A) shows an example of a mobile phone 1000 different from the mobile phone of FIG. 23(C). The mobile phone 1000 includes a display unit 1002 built into a housing 1001, an operation A button 1003, an external connection port 1004, a speaker 1005, a microphone 1006, etc. It is prepared.

[0267] The mobile phone 1000 shown in FIG. 25A displays information by touching the display unit 1002 with a finger or the like. In addition, operations such as making a phone call or sending an e-mail can be performed by using the display unit 1. This can be done by touching 002 with a finger or the like.

[0268] The screen of the display unit 1002 has three main modes. The first is a display mode that is mainly used for displaying images. The first mode is a display mode, the second is an input mode for inputting information such as characters, and the third mode is a display mode. This is a display + input mode that combines the display mode and the input mode.

[0269] For example, when making a call or composing an e-mail, the display unit 1002 is used for inputting characters. The main character input mode is to input characters displayed on the screen. It is preferable to display a keyboard or number buttons on most of the screen of the display unit 1002. I wish.

[0270] In addition, a sensor for detecting tilt, such as a gyro or an acceleration sensor, is installed inside the mobile phone 1000. By providing a detection device having the above configuration, the orientation of the mobile phone 1000 (portrait or landscape) can be determined and the display The screen display of the display unit 1002 can be automatically switched.

[0271] The screen mode can be changed by touching the display unit 1002 or by operating the housing 1001. This is done by operating the button 1003. Also, depending on the type of image displayed on the display unit 1002, For example, the image signal to be displayed on the display unit is a moving image. If it is data, the mode is switched to display mode, and if it is text data, the mode is switched to input mode.

[0272] In the input mode, the optical sensor of the display unit 1002 detects a signal and displays If there is no input by touch operation of the part 1002 for a certain period of time, the screen mode is changed to the input mode. Alternatively, the display mode may be switched from the normal mode to the display mode.

[0273] The display unit 1002 can also function as an image sensor. By touching the palm or fingers to the sensor 02, the palm print, fingerprint, etc. can be captured and identity authentication can be performed. In addition, the display unit may be equipped with a backlight that emits near-infrared light or a sensor that emits near-infrared light. By using a scanning light source, it is also possible to image finger veins, palm veins, etc.

[0274] FIG. 25B is also an example of a mobile phone. The mobile phone in FIG. 25B has a housing 9411. A display device 9410 including a display portion 9412 and an operation button 9413 and a housing 9401 An operation button 9402, an external input terminal 9403, a microphone 9404, a speaker 9405, and The communication device 9400 includes a light emitting unit 9406 that emits light when an incoming call is received, and has a display function. The display device 9410 can be attached to and detached from the communication device 9400 having a telephone function in the two directions shown by the arrows. Therefore, the display device 9410 and the communication device 9400 can be attached to each other with their short axes facing each other. The display device 9410 and the communication device 9400 can be attached to each other with their long axes facing each other. When only the function is required, the display device 9410 is removed from the communication device 9400, and the display device The communication device 9400 and the display device 9410 may be used alone. Images or input information can be sent and received via wireless or wired communication, and each can be recharged with a rechargeable battery. Has Terry. [Explanation of symbols]

[0275] 100 Substrates 101 Gate electrode 102 Gate insulating layer 103 Oxide semiconductor layer 105a Source electrode layer 105b Drain electrode layer 106a Source Area 106b Drain region 107 Protective insulation layer 108 Capacitance wiring 110 Pixel electrode 112 Scanning line driving circuit 120 Connection electrode 121 Terminal 122 Terminal 125 Contact Hole 126 Contact Hole 127 Contact Hole 128 Transparent Conductive Film 129 Transparent conductive film 141a n + layer 141b n + layer 146a Source Region 146b Drain region 142 n+ layer 143 n+ layer 144 n+ layer 145 n+ layer 150 Terminals 151 Terminal 152 Gate Insulation Layer 153 Connection electrode 154 Protective insulating film 155 Transparent conductive film 156 Electrode 170 Thin-film transistor 300 Substrates 301 Pixel section 302 Scanning line driving circuit 303 Signal line driver circuit 310 Substrate 311 Pixel section 312 Scanning line driver circuit 313 Scanning line driver circuit 314 Signal Line Driver Circuit 320 Substrate 322 Signal line input terminal 323 scan lines 324 Signal Line 327 Pixel section 328 pixels 329 pixel TFT 330 Holding capacity section 331 Pixel electrode 332 Capacitor Line 333 Common terminal 334 Protection circuit 335 Protection circuit 336 Protection circuit 337 Capacitive Bus Line 351 Flip-flop circuit 352 Control signal line 353 Control signal line 354 Control signal line 355 Control signal line 356 Control Signal Line 357 Reset Line 361 Logic Circuit Section 362 Switch section 363 TFT 364 TFT 365 TFT 366 TFT 367 TFT 368 TFT 369 TFT 370 TFT 371 TFT 372 TFT 373 EDMOS Circuit 381 Power line 382 Reset Line 383 Control Signal Line 384 Power line 385 Semiconductor Layer 386 wiring layer 387 Wiring layer 388 wiring layer 389 Contact Hole 390 Control Signal Line 400 Substrates 401 Gate electrode 402 Gate electrode 403 Gate Insulation Layer 404 Contact Hole 405 Oxide semiconductor layer 406a n+ layer 406b n+ layer 408a n+ layer 408b n+ layer 407 Oxide Semiconductor Layer 409 Wiring 410 Wiring 411 Wiring 412 Gate Insulation Layer 420 n+ layer 423 n+ layer 425 n+ layer 430 Thin Film Transistor 431 Thin Film Transistor 432 Thin Film Transistor 433 Thin Film Transistor 470 Gate electrode 471 Electrode 471 Gate electrode 472 Electrode 473 Insulating Layer 474 Electrode 475 Light-emitting layer 476 Electrode 480 Thin Film Transistor 581 Thin Film Transistor 585 Insulation Layer 587 Electrode layer 588 Electrode layer 589 Spherical particles 590a black area 590b White area 594 Cavity 595 Filling material 1000 Mobile Phones 1001 Case 1002 Display section 1003 Operation button 1004 External connection port 1005 Speaker 1006 Mike 2600 TFT substrate 2601 Opposing substrate 2602 Sealing material 2603 Pixel section 2604 Display element 2605 Colored layer 2606 Polarizing plate 2607 Polarizing plate 2608 Wiring circuit section 2609 Flexible wiring board 2610 cold cathode tube 2611 Reflector 2612 Circuit Board 2613 Diffuser 4001 Board 4002 Pixel section 4003 Signal line driver circuit 4004 Scanning line driver circuit 4005 Sealing material 4006 Substrate 4008 Liquid crystal layer 4010 Thin film transistor 4011 Thin film transistor 4013 Liquid crystal element 4015 Connection terminal electrode 4016 Terminal electrode 4018 FPC 4019 Anisotropic conductive film 4020 Insulation layer 4020 Insulation layer (insulation layer 4021 Insulation layer 4030 Pixel electrode layer 4031 Counter electrode layer 4032 Insulation layer 4501 Board 4502 Pixel section 4503a Signal line driver circuit 4504a Scanning line driver circuit 4518a FPC 4505 Sealing material 4506 Board 4507 Filling material 4509 Thin-film transistor 4510 Thin-film transistor 4511 Light emitting element 4512 Electroluminescent layer 4513 Electrode layer 4515 Connection terminal electrode 4516 Terminal electrode 4517 Electrode layer 4519 Anisotropic conductive film 4520 Bulkhead 6400 pixels 6401 Switching transistor 6402 Driving transistor 6403 Capacitor 6404 Light emitting element 6405 Signal Line 6406 scan lines 6407 Power line 6408 Common electrode 7001 TFT 7002 Light emitting element 7003 Cathode 7004 Light-emitting layer 7005 Anode 7011 Driving TFT 7012 Light emitting element 7013 Cathode 7014 Light-emitting layer 7015 Anode 7016 Shielding membrane 7017 Conductive film 7021 Driving TFT 7022 Light emitting element 7023 Cathode 7024 Light-emitting layer 7025 Anode 7027 Conductive film 9100 Mobile Phone 9101 Case 9102 Case 9103 Connection section 9104 Display section 9106 Operation key 9200 Portable information terminal equipment 9201 Case 9202 Display section 9203 Case 9205 Keyboard 9207 Connection section 9300 Computer 9301 Case 9302 Case 9303 Display section 9304 Keyboard 9400 Communication Equipment 9401 Case 9402 Operation button 9403 External input terminal 9404 Microphone 9405 Speaker 9406 Light emitting part 9410 Display device 9411 Housing 9412 Display section 9413 Operation button 9500 Digital Video Camera 9501 Case 9503 Display section 9600 Television Equipment 9601 Case 9603 Display section 9605 Stand 9607 Display section 9609 Operation key 9610 Remote control device 9700 Digital Photo Frame 9701 Case 9703 Display section

Claims

1. a first transistor to a ninth transistor and a first wiring to a seventh wiring; one of a source and a drain of the first transistor is always electrically connected to the first wiring, the other of the source and the drain of the first transistor is always electrically connected to the second wiring; one of the source and the drain of the second transistor is always electrically connected to the third wiring; the other of the source and the drain of the second transistor is always electrically connected to the first wiring; one of the source and the drain of the third transistor is always electrically connected to the fourth wiring; the other of the source and the drain of the third transistor is always electrically connected to the second wiring; a gate of the third transistor is always electrically connected to a gate of the first transistor; one of the source and the drain of the fourth transistor is always electrically connected to the third wiring; the other of the source and the drain of the fourth transistor is always electrically connected to the fourth wiring; a gate of the fourth transistor is always electrically connected to a gate of the second transistor; one of the source and the drain of the fifth transistor is always electrically connected to the gate of the eighth transistor; the gate of the fifth transistor is always electrically connected to the fifth wiring; one of the source and the drain of the sixth transistor is always electrically connected to the third wiring, the other of the source and the drain of the sixth transistor is always electrically connected to the gate of the eighth transistor; a gate of the sixth transistor is always electrically connected to a gate of the second transistor; one of the source and the drain of the seventh transistor is always electrically connected to the gate of the second transistor; the other of the source and the drain of the seventh transistor is always electrically connected to the sixth wiring; the gate of the seventh transistor is always electrically connected to the sixth wiring; one of the source and the drain of the eighth transistor is always electrically connected to the third wiring, the other of the source and the drain of the eighth transistor is always electrically connected to the gate of the second transistor; one of the source and the drain of the ninth transistor is always electrically connected to the gate of the eighth transistor; the gate of the ninth transistor is always electrically connected to the seventh wiring; when one of a source and a drain of the sixth transistor is electrically connected to a gate of the first transistor through at least a channel formation region of the sixth transistor, a potential of the third wiring is supplied to the gate of the first transistor through at least a channel formation region of the sixth transistor, a first conductive film having a function as one of a source or a drain of the second transistor and a function as one of a source or a drain of the fourth transistor has a function as the third wiring, the first conductive film has a region intersecting with a second conductive film having a function as a gate of the sixth transistor; Semiconductor device.

2. a first transistor to a ninth transistor and a first wiring to a seventh wiring; one of a source and a drain of the first transistor is always electrically connected to the first wiring, the other of the source and the drain of the first transistor is always electrically connected to the second wiring; one of the source and the drain of the second transistor is always electrically connected to the third wiring; the other of the source and the drain of the second transistor is always electrically connected to the first wiring; one of the source and the drain of the third transistor is always electrically connected to the fourth wiring; the other of the source and the drain of the third transistor is always electrically connected to the second wiring; a gate of the third transistor is always electrically connected to a gate of the first transistor; one of the source and the drain of the fourth transistor is always electrically connected to the third wiring; the other of the source and the drain of the fourth transistor is always electrically connected to the fourth wiring; a gate of the fourth transistor is always electrically connected to a gate of the second transistor; one of the source and the drain of the fifth transistor is always electrically connected to the gate of the eighth transistor; the gate of the fifth transistor is always electrically connected to the fifth wiring; one of the source and the drain of the sixth transistor is always electrically connected to the third wiring, the other of the source and the drain of the sixth transistor is always electrically connected to the gate of the eighth transistor; a gate of the sixth transistor is always electrically connected to a gate of the second transistor; one of the source and the drain of the seventh transistor is always electrically connected to the gate of the second transistor; the other of the source and the drain of the seventh transistor is always electrically connected to the sixth wiring; the gate of the seventh transistor is always electrically connected to the sixth wiring; one of the source and the drain of the eighth transistor is always electrically connected to the third wiring, the other of the source and the drain of the eighth transistor is always electrically connected to the gate of the second transistor; one of the source and the drain of the ninth transistor is always electrically connected to the gate of the eighth transistor; the gate of the ninth transistor is always electrically connected to the seventh wiring; when one of a source and a drain of the sixth transistor is electrically connected to a gate of the first transistor through at least a channel formation region of the sixth transistor, a potential of the third wiring is supplied to the gate of the first transistor through at least a channel formation region of the sixth transistor, a first conductive film having a function as one of a source or a drain of the second transistor and a function as one of a source or a drain of the fourth transistor has a function as the third wiring, the first conductive film has a region intersecting with a second conductive film having a function as a gate of the sixth transistor; the first wiring has a function of outputting a first signal to be supplied to a pixel portion; the second wiring has a function of inputting a clock signal; the third wiring has a function of inputting a power supply potential; The fourth wiring has a function of outputting a second signal. Semiconductor device.

3. a first transistor to a ninth transistor and a first wiring to a seventh wiring; one of a source and a drain of the first transistor is always electrically connected to the first wiring, the other of the source and the drain of the first transistor is always electrically connected to the second wiring; one of the source and the drain of the second transistor is always electrically connected to the third wiring; the other of the source and the drain of the second transistor is always electrically connected to the first wiring; one of the source and the drain of the third transistor is always electrically connected to the fourth wiring; the other of the source and the drain of the third transistor is always electrically connected to the second wiring; a gate of the third transistor is always electrically connected to a gate of the first transistor; one of the source and the drain of the fourth transistor is always electrically connected to the third wiring; the other of the source and the drain of the fourth transistor is always electrically connected to the fourth wiring; a gate of the fourth transistor is always electrically connected to a gate of the second transistor; one of the source and the drain of the fifth transistor is always electrically connected to the gate of the eighth transistor; the gate of the fifth transistor is always electrically connected to the fifth wiring; one of the source and the drain of the sixth transistor is always electrically connected to the third wiring, the other of the source and the drain of the sixth transistor is always electrically connected to the gate of the eighth transistor; a gate of the sixth transistor is always electrically connected to a gate of the second transistor; one of the source and the drain of the seventh transistor is always electrically connected to the gate of the second transistor; the other of the source and the drain of the seventh transistor is always electrically connected to the sixth wiring; the gate of the seventh transistor is always electrically connected to the sixth wiring; one of the source and the drain of the eighth transistor is always electrically connected to the third wiring, the other of the source and the drain of the eighth transistor is always electrically connected to the gate of the second transistor; one of the source and the drain of the ninth transistor is always electrically connected to the gate of the eighth transistor; the gate of the ninth transistor is always electrically connected to the seventh wiring; when one of a source and a drain of the sixth transistor is electrically connected to a gate of the first transistor through at least a channel formation region of the sixth transistor, a potential of the third wiring is supplied to the gate of the first transistor through at least a channel formation region of the sixth transistor, a first conductive film having a function as one of a source or a drain of the second transistor and a function as one of a source or a drain of the fourth transistor has a function as the third wiring, the first conductive film has a region intersecting with a second conductive film having a function as a gate of the sixth transistor; a third conductive film having a function as a gate of the first transistor and a function as a gate of the third transistor has a region intersecting with a fourth conductive film having a function as one of a source and a drain of the first transistor and a function as the other of a source and a drain of the second transistor; Semiconductor device.

4. a first transistor to a ninth transistor and a first wiring to a seventh wiring; one of a source and a drain of the first transistor is always electrically connected to the first wiring, the other of the source and the drain of the first transistor is always electrically connected to the second wiring; one of the source and the drain of the second transistor is always electrically connected to the third wiring; the other of the source and the drain of the second transistor is always electrically connected to the first wiring; one of the source and the drain of the third transistor is always electrically connected to the fourth wiring; the other of the source and the drain of the third transistor is always electrically connected to the second wiring; a gate of the third transistor is always electrically connected to a gate of the first transistor; one of the source and the drain of the fourth transistor is always electrically connected to the third wiring; the other of the source and the drain of the fourth transistor is always electrically connected to the fourth wiring; a gate of the fourth transistor is always electrically connected to a gate of the second transistor; one of the source and the drain of the fifth transistor is always electrically connected to the gate of the eighth transistor; the gate of the fifth transistor is always electrically connected to the fifth wiring; one of the source and the drain of the sixth transistor is always electrically connected to the third wiring, the other of the source and the drain of the sixth transistor is always electrically connected to the gate of the eighth transistor; a gate of the sixth transistor is always electrically connected to a gate of the second transistor; one of the source and the drain of the seventh transistor is always electrically connected to the gate of the second transistor; the other of the source and the drain of the seventh transistor is always electrically connected to the sixth wiring; the gate of the seventh transistor is always electrically connected to the sixth wiring; one of the source and the drain of the eighth transistor is always electrically connected to the third wiring, the other of the source and the drain of the eighth transistor is always electrically connected to the gate of the second transistor; one of the source and the drain of the ninth transistor is always electrically connected to the gate of the eighth transistor; the gate of the ninth transistor is always electrically connected to the seventh wiring; when one of a source and a drain of the sixth transistor is electrically connected to a gate of the first transistor through at least a channel formation region of the sixth transistor, a potential of the third wiring is supplied to the gate of the first transistor through at least a channel formation region of the sixth transistor, a first conductive film having a function as one of a source or a drain of the second transistor and a function as one of a source or a drain of the fourth transistor has a function as the third wiring, the first conductive film has a region intersecting with a second conductive film having a function as a gate of the sixth transistor; a third conductive film having a function as a gate of the first transistor and a function as a gate of the third transistor has a region intersecting with a fourth conductive film having a function as one of a source or a drain of the first transistor and a function as the other of the source or the drain of the second transistor; the first wiring has a function of outputting a first signal to be supplied to a pixel portion; the second wiring has a function of inputting a clock signal; the third wiring has a function of inputting a power supply potential; The fourth wiring has a function of outputting a second signal. Semiconductor device.

5. In any one of claims 1 to 4, the first transistor to the ninth transistor all have the same channel type; Semiconductor device.

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