Light-emitting device

Abstract

To form a plurality of kinds of circuits on the same substrate to provide a light-emitting device having several kinds of thin film transistors, each tailored to characteristics of the plurality of kinds of circuits.SOLUTION: As a thin film transistor for a pixel, an inverted coplanar type having an oxide semiconductor layer is used that overlaps with a source electrode layer and a drain electrode layer. As a thin film transistor for a drive circuit, a channel stop type is used. At a position that overlaps with a light emitting element electrically connected to the thin film transistor for a pixel, a color filter layer is provided between the thin film transistor and the light emitting element.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a light-emitting device having a layer containing an organic compound as a light-emitting layer, and a method for manufacturing the same. The present invention relates to an electronic device that incorporates a light-emitting display device having a light-emitting element as a component. [Background technology]

[0002] The organic compound used as the light emitter has characteristics such as being thin and lightweight, having high-speed response, and being driven by low DC voltage. The light-emitting element used is being considered for application in next-generation flat panel displays and lighting. In particular, display devices in which light-emitting elements are arranged in a matrix are being considered as being superior to conventional liquid crystal display devices. Compared to conventional LCD devices, it is believed that its advantages lie in its wider viewing angle and superior visibility.

[0003] The light-emitting mechanism of a light-emitting element is to sandwich an EL layer between a pair of electrodes and apply a voltage to the layer. Electrons injected from the electrode and holes injected from the anode recombine and split at the luminescence centers of the EL layer. When the molecular excitons relax to the ground state, they release energy and emit light. There are two types of excited states: singlet and triplet. It is believed that this is possible even after passing through a wake-up state.

[0004] The EL layer constituting the light-emitting element has at least a light-emitting layer. In addition, a laminated structure having a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, etc. may be used. It is also possible.

[0005] Metal oxides are also attracting attention as materials that exhibit semiconducting properties. Examples of oxides include tungsten oxide, tin oxide, indium oxide, and zinc oxide. There are thin-film transistors in which metal oxides that exhibit such semiconducting properties are used as channel formation regions. Such a capacitor is already known (Patent Document 1 and Patent Document 2).

[0006] In addition, the TFT using an oxide semiconductor has a high field effect mobility. It is also possible to configure a driving circuit for a display device or the like using the above. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2007-123861 A [Patent Document 2] JP 2007-96055 A Summary of the Invention [Problem to be solved by the invention]

[0008] When forming a plurality of different circuits on an insulating surface, for example, a pixel section and a driver circuit are formed on the same substrate. In the case where the thin film transistor used in the pixel portion is formed in the same manner as the pixel portion, the thin film transistor has excellent switching characteristics, e.g. For example, a large on-off ratio is required, and the thin-film transistors used in the drive circuits have high operating speeds. In particular, the higher the resolution of the display device, the faster the display image quality. Since the image writing time is shortened, the thin film transistors used in the driver circuits can operate at high speed and It is preferable to do so.

[0009] Multiple types of circuits are formed on the same substrate, and multiple types of thin films are used to match the characteristics of each type of circuit. An object of the present invention is to provide a light-emitting device including a film transistor.

[0010] According to one embodiment of the present invention, a thin film transistor having favorable electrical characteristics and high reliability is used as a switching element. It is an object of the present invention to manufacture a highly reliable light-emitting device by using the organic EL element as a semiconductor material. [Means for solving the problem]

[0011] One embodiment of the present invention is a display device having a driver circuit portion and a display portion (also referred to as a pixel portion) over the same substrate. The driving circuit portion has a gate electrode layer, a source electrode layer, and a drain electrode layer formed of a metal conductive film. A thin film transistor for a driving circuit, the thin film transistor being configured so that a channel layer is configured from an oxide semiconductor. and a driving circuit wiring formed of a metal conductive film, and the display unit has a source electrode The drain electrode layer and the drain electrode layer are made of an oxide conductor and the semiconductor layer is made of an oxide semiconductor. and a pixel thin film transistor configured as above.

[0012] Bottom-gate thin-film transistors are used as thin-film transistors for pixels and thin-film transistors for driver circuits. The pixel thin film transistor is formed on the source electrode layer and the drain electrode layer. A thin film transistor having an inverted coplanar type (also called a bottom-contact type) and an oxide semiconductor layer overlapping the It is a transistor.

[0013] In addition, light-emitting elements of multiple types of luminescent colors and pixel elements electrically connected to the light-emitting elements are formed on the same substrate. Thin film transistors can be formed to manufacture light emitting devices such as displays.

[0014] In addition, a plurality of light-emitting elements that emit white light are provided, and the light-emitting areas of the respective light-emitting elements are overlapped. An optical film, specifically a color filter, is provided on the display to create a full-color light-emitting display device. A color filter is placed between the white light-emitting element and the pixel thin-film transistor. When light emitted from a light-emitting element is passed through a color filter to display a picture, a thin film for a pixel is provided. The gate electrode layer, the source electrode layer, and the drain electrode layer of the transistor are made of a light-transmitting material. By using a conductive film having a color filter, the aperture ratio can be improved. The photodiode is a three-color filter layer including a black matrix and an overcoat. This refers to the entire film that has a color filter (such as a blue filter, a green filter, etc.). The term does not refer to a single color filter, but rather to a color filter of one color.

[0015] In addition, the thin film transistor for the driver circuit has a different structure from the thin film transistor for the pixel. An oxide insulating layer is provided between the source electrode layer and the drain electrode layer and in contact with the exposed oxide semiconductor layer. The bottom-gate thin-film transistor is

[0016] The thin film transistor for the driver circuit has a drain electrode layer made of a metal conductive film such as Ti, A high-resistance drain electrode layer that is an oxygen-deficient type and is in contact with a part of the top surface of the oxide semiconductor layer and overlaps with the drain electrode layer. The shape of the drain region (also called the High Resistance Drain (HRD) region) Specifically, the carrier concentration of the high-resistance drain region is 1×10 18 / cm 3 Below The carrier concentration in the channel formation region is at least 1×10 18 / cm 3 The carrier concentration in this specification is the Hall effect region at room temperature. This refers to the carrier concentration value obtained through measurement.

[0017] The source electrode layer is in contact with a part of a top surface of the oxide semiconductor layer and overlaps with an oxygen-deficient region. The high resistance source region (HRS) is a depleted type. ) region) is formed.

[0018] One embodiment of the present invention disclosed in this specification is a pixel having a first thin film transistor over the same substrate. A driving circuit having a second thin film transistor having a structure different from that of the first thin film transistor. The first thin film transistor has a gate electrode layer on the substrate and a gate electrode layer on the gate electrode layer. A source electrode layer and a drain electrode layer are formed on the gate insulating layer, and a source insulating layer and a drain electrode layer are formed on the gate insulating layer. An oxide semiconductor layer overlapping the source electrode layer and the drain electrode layer, and an oxide semiconductor layer in contact with the oxide semiconductor layer a connection electrode layer electrically connected to the drain electrode layer on the oxide insulating layer; A color filter layer is formed on the insulating layer, and a third electrode layer is formed on the color filter layer and electrically connected to the connection electrode layer. A first electrode is provided on the first electrode, a light-emitting layer is provided on the light-emitting layer, and a second electrode is provided on the light-emitting layer. Transistor gate electrode layer, gate insulating layer, oxide semiconductor layer, source electrode layer, drain electrode The layer, the oxide insulating layer, and the first electrode constitute a light-transmitting light-emitting device.

[0019] The above configuration solves at least one of the above problems.

[0020] In the above configuration, the connection electrode layer is made of Al, Cr, Cu, Ta, Ti, Mo, or W. Using a laminated film that combines a film mainly composed of the selected element or an alloy film of the selected element The source electrode layer and the drain electrode layer of the first thin film transistor are made of indium oxide. Indium oxide, tin oxide, indium oxide zinc oxide, or zinc oxide do.

[0021] Also, the source electrode layer and the drain electrode layer of the second thin film transistor, which is a thin film transistor for a driving circuit, The rain electrode layer is made of the same material as the connection electrode layer, and is made of Ti, Mo, W, Al, Cr, Cu, T a. An element selected from the above, or an alloy containing the above elements, or a combination of the above elements The source electrode layer and the drain electrode layer are each formed of a single layer containing the above-mentioned element. Without limitation, a stack of two or more layers can be used.

[0022] The source electrode layer and the drain electrode layer of the second thin film transistor are made of an oxide semiconductor layer. It does not overlap with the channel formation region. It also functions as a channel protection layer. The side surface of the source electrode layer and the drain electrode layer facing the side surface are wider than the width of the oxide insulating layer. The distance between the side of the layer is wider. The operating speed of the thin film transistor for the driver circuit is increased. In order to achieve this, the width (width in the channel length direction) of the oxide insulating layer that functions as a channel protection layer is made small. When designing the source electrode layer so that the side of the drain electrode layer facing the side of the source electrode layer is narrow, The distance between the surface also becomes smaller, which may cause a short circuit between the source electrode layer and the drain electrode layer. In addition, it is useful to increase the distance between the electrodes. This increases the circuit integration density.

[0023] In the above structure, the second thin film transistor includes an oxide semiconductor layer. an oxide insulating layer over a semiconductor layer; The oxide semiconductor layer has a structure in which a peripheral portion of the oxide semiconductor layer is in contact with an oxide insulating layer. The oxide insulating layer in contact with the channel functions as a channel protection layer.

[0024] In the above structure, the insulating film functions as a channel protection layer for the thin film transistor for the driver circuit. The oxide insulating layer is formed using an inorganic insulating film formed by a sputtering method, typically a silicon oxide film or a nitride oxide film. A silicon film, an aluminum oxide film, an aluminum oxynitride film, or the like is used.

[0025] The second thin film transistor has an oxide semiconductor layer between the oxide semiconductor layer and the source electrode layer. Alternatively, an oxide conductive layer may be provided between the drain electrode layer and the drain electrode layer. By adopting this structure, the contact resistance can be reduced, enabling high-speed operation of thin-film transistors. The oxide conductive layer preferably contains zinc oxide as a component. It is preferable that the oxide conductive layer does not contain indium oxide. , zinc oxide, zinc aluminum oxide, zinc aluminum oxynitride, zinc gallium oxide, etc. Some examples include:

[0026] In addition, the oxide semiconductor layer of the driver circuit thin film transistor has an upper surface a region that does not overlap with the oxide insulating layer, the drain electrode layer, and the source electrode layer, i.e., a third region The width of the third region in the channel length direction is determined based on the patterning position of the oxide semiconductor layer. , and the patterning positions of the drain electrode layer and the source electrode layer. If the width of the region in the channel length direction is widened, the off-current of the thin film transistor for the driver circuit can be reduced. In addition, if the width of the third region in the channel length direction is narrowed, The operating speed of the thin film transistor for the driver circuit can be increased.

[0027] The insulating layer in contact with the third region is also made of an inorganic insulating film formed by sputtering, typically a nitride film. A silicon nitride film, a silicon oxide nitride film, an aluminum nitride film, or the like is used.

[0028] The oxide semiconductor layer is InMO3(ZnO) mA thin film expressed as (m>0) A thin film transistor is fabricated using the thin film as an oxide semiconductor layer. contains one or more metal elements selected from Ga, Fe, Ni, Mn and Co. For example, M can be Ga, Ga and Ni, or Ga and Fe, etc. In some cases, the above-mentioned metal elements other than Ga are contained. In addition to the metallic elements contained as impurities, there are also Fe, Ni and other transition metal elements, In the present specification, InMO3(Z nO) m Among oxide semiconductor layers having a structure represented by (m>0), a structure containing Ga as M The oxide semiconductor is called the In-Ga-Zn-O oxide semiconductor, and the thin film of the In-Ga- It is also called a Zn-O-based non-single crystal film.

[0029] In addition to the above, metal oxides that can be used for the oxide semiconductor layer include In-Sn-O, I n-Sn-Zn-O system, In-Al-Zn-O system, Sn-Ga-Zn-O system, Al-Ga -Zn-O series, Sn-Al-Zn-O series, In-Zn-O series, Sn-Zn-O series, Al- Zn-O, In-O, Sn-O, and Zn-O metal oxides can be used. Further, the oxide semiconductor layer made of the above metal oxide may contain silicon oxide.

[0030] In addition, one embodiment of the present invention is a method for manufacturing a semiconductor device comprising the steps of: forming a first gate electrode layer and a second gate electrode layer over a substrate having an insulating surface; A gate electrode layer is formed, and a gate insulating layer is formed on the first gate electrode layer and the second gate electrode layer. A first source electrode layer and a first drain electrode layer are formed on the gate insulating layer and overlap the first gate electrode layer. A first gate electrode layer and a part of a first source electrode layer are formed on the gate insulating layer. a first oxide semiconductor layer overlapping a part of the first drain electrode layer; and a second gate electrode. a second oxide semiconductor layer overlapping the first oxide semiconductor layer and being in contact with a part of the second oxide semiconductor layer; forming an oxide insulating layer in contact with an upper surface and a side surface of the second oxide semiconductor layer; A second source electrode layer and a second drain electrode layer are formed on the semiconductor layer, and a first drain electrode layer is formed on the oxide insulating layer. A connection electrode layer is formed to be electrically connected to the first oxide semiconductor layer, and an oxide semiconductor layer is formed to overlap the first oxide semiconductor layer. A color filter layer is formed on the insulating layer, and the color filter layer is electrically connected to the connection electrode layer. The method for producing a light emitting device includes forming a first electrode, a light emitting layer, and a second electrode in succession.

[0031] In the above-described manufacturing method, The oxide insulating layer is formed by dehydrating or dehydrogenating the oxide semiconductor layer and then exposing it to the air. In this case, impurities such as water and hydrogen are prevented from re-entering the oxide semiconductor layer.

[0032] Dehydration or dehydrogenation is performed using inert gases such as nitrogen or noble gases (argon, helium, etc.). The heat treatment is performed at a temperature of 400° C. or higher and lower than the distortion point of the substrate in an atmosphere, and the moisture content of the oxide semiconductor layer is Reduces impurities such as minerals.

[0033] Under an inert gas atmosphere of nitrogen or rare gas (argon, helium, etc.), or under reduced pressure When the heat treatment is performed, the oxide semiconductor layer becomes oxygen-deficient and has low resistance. , that is, N-type (N - Then, an oxide insulating film is formed in contact with the oxide semiconductor layer. By carrying out the above process, the oxide semiconductor layer is made into an oxygen-excessive state, and thus the resistance is increased, that is, the oxide semiconductor layer is made into an I-type. This makes it possible to obtain thin-film transistors with good electrical characteristics and high reliability. It is therefore possible to manufacture and provide a semiconductor device having the above-mentioned characteristics.

[0034] The oxide semiconductor layer that has been dehydrated or dehydrogenated is Even when TDS was measured up to 450°C for the layer, two peaks of water and at least 300 The heat treatment conditions are set so that a peak that appears around 100 °C is not detected. The TDS test showed that the thin-film transistor using the oxide semiconductor layer that was dehydrogenated or dehydrogenated had a thermal conductivity of 45 Even when measurements are taken down to 0°C, the water peak that appears around 300°C is not detected.

[0035] Then, the oxide semiconductor layer is heated to a temperature T at which the oxide semiconductor layer is dehydrated or dehydrogenated. To a temperature that is high enough to prevent impurities such as hydrogen from entering, specifically, 100°C higher than the heating temperature T Do not expose to air in the same furnace used for dehydration or dehydrogenation. It is important not to reintroduce water or hydrogen without first dehydrating or dehydrogenating the The oxide semiconductor layer is made low-resistance, that is, made N-type (N - , N + After that, the resistance is increased. When a thin film transistor is manufactured using an oxide semiconductor layer that is an i-type, The threshold voltage value of the switching element can be set to positive, so that the switching element is a normally-off switching element. This can be achieved by setting the gate voltage of the thin film transistor to a positive threshold voltage as close as possible to 0V. It is desirable for a display device to have a channel formed. If the voltage is negative, a current flows between the source and drain electrodes even if the gate voltage is 0V. In active matrix display devices, the transistors tend to be normally on. For this purpose, the electrical characteristics of the thin film transistors that make up the circuit are important, and these electrical characteristics In particular, the threshold voltage (Vth ) is important. Even if the field effect mobility is high, the threshold voltage is high, or If the value is negative, it is difficult to control the circuit. In the case of a thin-film transistor with a large absolute value of the threshold voltage, T It may not be able to perform the switching function of FT and may become a load. In the case of a diode-type thin-film transistor, a channel is formed only when a positive voltage is applied to the gate. A transistor that is formed so that a drain current flows out is desirable. There are transistors in which no channel is formed, and transistors in which a channel is formed even under negative voltage conditions and the drain A transistor through which a current flows is not suitable as a thin film transistor for use in a circuit.

[0036] In addition, the gas atmosphere used to lower the temperature from T is different from the gas atmosphere used to raise the temperature to T. A gas atmosphere may be switched to, for example, air in the same furnace where dehydration or dehydrogenation was performed. The inside of the furnace is filled with high-purity oxygen gas or N2O gas, ultra-dry air (dew point Cooling is performed by filling the container with water at a temperature of -40°C or less, preferably -60°C or less.

[0037] The moisture content in the film is reduced by a heat treatment for dehydration or dehydrogenation, and then the film is Cool slowly (or cool) in an atmosphere that is not prone to dew (dew point is -40°C or less, preferably -60°C or less). The oxide semiconductor film is used to improve the electrical characteristics of thin film transistors and to facilitate mass production. This will realize thin-film transistors that are both reliable and high performance.

[0038] In this specification, under an inert gas atmosphere of nitrogen or rare gas (argon, helium, etc.), Alternatively, the heat treatment under reduced pressure is called a heat treatment for dehydration or dehydrogenation. The term "dehydrogenation" refers only to the process of desorption of hydrogen as H2 by this heat treatment. For convenience, this term is used to refer to the elimination of H, OH, etc. Let us assume that.

[0039] 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 light emitting device has a portion for connecting a drain wiring. In the driving circuit, the gate electrode of the thin film transistor and the source The semiconductor device has a portion for connecting a wiring or a drain wiring.

[0040] In addition, since thin-film transistors are easily damaged by static electricity, etc., For the line, a protection circuit for protecting the thin film transistor in the pixel area can be provided on the same substrate. The protection circuit is preferably formed using a nonlinear element using an oxide semiconductor layer. It is nice.

[0041] 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

[0042] The semiconductor device according to one embodiment of the present invention includes a driver circuit having a TFT for a driver circuit on the same substrate. A display section having a path section and a pixel TFT is manufactured. can be reduced.

[0043] In addition, a white light emitting element can be formed on the substrate to manufacture a light emitting device such as a lighting device. The lighting device is particularly an electroluminescent device. The present invention relates to a lighting device using a light-emitting element having a layer containing a light-emitting material that can obtain an EL (electroluminescence) light-emitting diode. It is a bright device. Effect of the Invention

[0044] By using an oxide semiconductor layer that has been subjected to heat treatment for dehydration or dehydrogenation, Thin-film transistors with excellent electrical characteristics and high reliability are used as switching elements, It is also possible to fabricate a high-performance light-emitting device by forming a TFT for pixels and a TFT for driving circuits on the same substrate. Light-emitting devices can be fabricated by combining FT and each circuit in a different structure. . [Brief description of the drawings]

[0045] [Figure 1] 1A to 1C are cross-sectional process diagrams illustrating one embodiment of the present invention. [Diagram 2] FIG. 1 is a circuit diagram illustrating one embodiment of the present invention. [Diagram 3] FIG. 1 is a cross-sectional view showing one embodiment of the present invention. [Figure 4] FIG. 1 is a cross-sectional view showing one embodiment of the present invention. [Diagram 5] 1A and 1B are cross-sectional views and a plan view illustrating one embodiment of the present invention. [Figure 6] FIG. 1 is a cross-sectional view showing one embodiment of the present invention. [Figure 7] 1A and 1B are cross-sectional views and a plan view illustrating one embodiment of the present invention. [Figure 8] FIG. 1 is a cross-sectional view showing one embodiment of the present invention. [Figure 9]FIG. 1 is a block diagram illustrating a semiconductor device. [Figure 10] 1A and 1B are a diagram illustrating a configuration of a signal line driver circuit and a timing chart. [Figure 11] FIG. 2 is a diagram showing a configuration of a shift register. [Figure 12] 4A and 4B are a timing chart and a circuit diagram illustrating the operation of a shift register. [Figure 13] FIG. [Figure 14] FIG. [Figure 15] FIG. [Figure 16] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] 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 limited to the description of the following embodiments. In the drawings in this specification, parts having the same parts or similar functions are The same reference numerals will be used to denote the same parts, and their explanations may be omitted.

[0047] (Embodiment 1) In this embodiment mode, a light-emitting device and a manufacturing method thereof will be described with reference to FIGS. Figure 1(E) shows the cross-sectional structure of two thin-film transistors with different structures fabricated on the same substrate. An example is shown below.

[0048] The thin film transistor 450 shown in FIG. 1E is one of the bottom gate structures. The Transistor 460 is a bottom-gate transistor called a bottom-contact type (also called an inverted coplanar type). It is one of the structures.

[0049] The thin film transistor 460 disposed in the pixel is a bottom contact type thin film transistor. A gate electrode layer 451a, a gate insulating layer 402, a gate insulating film 403, a gate insulating film 404, a gate insulating film 405, a gate insulating film 406, a gate insulating film 407, a gate insulating film 408, a gate insulating film 409, a gate insulating film 410, a gate insulating film 411, a gate insulating film 412, a gate insulating film 413, a gate insulating film 414, The oxide semiconductor layer 454 including the channel formation region, the source electrode layer 455a, and the drain electrode In addition, the thin film transistor 460 is covered with the oxide semiconductor layer 454. An oxide insulating layer 426b is provided in contact with the side surface.

[0050] In addition, the thin film transistor 460 disposed in the pixel is a thin film transistor having a single gate structure. However, if necessary, a multi-gate structure having a plurality of channel forming regions may be used. A thin film transistor having the above structure can also be formed.

[0051] Note that the oxide semiconductor layer 454 is a gate insulating layer between the source electrode layer 455a and the drain electrode layer 455b. The oxide semiconductor layer 454 is formed above and partially overlaps the gate electrode layer 451. a via the gate insulating layer 402. The channel formation region of the oxide semiconductor layer 454 is located between the side surface of the source electrode layer 455a and the side surface of the oxide semiconductor layer 454. The region between the side surface and the side surface of the drain electrode layer 455b facing the side surface, that is, the gate insulating layer This is a region that contacts the edge layer 402 and overlaps with the gate electrode layer 451a.

[0052] In addition, the thin film transistor 460 is a light-transmitting thin film transistor having a high aperture ratio. In order to realize a light-emitting device, the source electrode layer 455a and the drain electrode layer 455b are A conductive film having optical properties is used.

[0053] In addition, a gate electrode layer 451a of the thin film transistor 460 is also formed using a light-transmitting conductive film. In this specification, a film that is transparent to visible light has a visible light transmittance of 75 to 10. If the film is conductive, it is also called a transparent conductive film. Alternatively, a conductive film that is semi-transparent to visible light may be used. This refers to a light transmittance of 50 to 75%.

[0054] In addition, the thin film transistor 450 disposed in the driving circuit is formed on the substrate 400 having an insulating surface. , a gate electrode layer 421a, a gate insulating layer 402, at least a channel forming region 423, An oxide semiconductor layer having a resistive source region 424a and a high-resistance drain region 424b. The source electrode layer 425a and the drain electrode layer 425b are also included in the channel formation region 42 An oxide insulating layer 426a in contact with the source electrode layer 425a and An insulating layer 428 is provided over the drain electrode layer 425b.

[0055] In addition, the first region 424c and the second region 424b of the oxide semiconductor layer overlap with the oxide insulating layer 426b. 4d is in the same oxygen-excess state as the channel formation region 423, and is effective in reducing leakage current and reducing parasitic capacitance. The insulating layer 428 also serves to reduce parasitic capacitance. The third region 424e is provided between the channel formation region 423 and the high resistance source region 424a. The fourth region 424f of the oxide semiconductor layer in contact with the insulating layer 428 is a channel formation region. The oxide layer 428 is disposed between the high-resistance drain region 423 and the high-resistance drain region 424b. The third region 424e and the fourth region 424f of the semiconductor layer can reduce the off-current. do.

[0056] In addition, the channel protection type thin film transistor has a channel length L of the channel formation region that is shortened. In order to achieve this, the width of the oxide insulating layer is narrowed, and the source electrode layer and the drain electrode layer are formed on the narrow oxide insulating layer. If a thin oxide insulating layer is provided, there is a risk of short circuiting on the oxide insulating layer. The source electrode layer 425a and the drain electrode layer 425b are provided at ends apart from the edge layer 426a. This is the configuration.

[0057] In FIG. 1E, the oxide insulating layer 426a serving as a channel protective layer and the gate The region of the oxide semiconductor layer where the electrode layer overlaps with the gate insulating layer via the gate insulating layer is called a channel formation region. Therefore, the channel length L of the thin film transistor 450 is The channel length L of the thin film transistor 450 is equal to the width in the channel length direction. The length at the interface with the insulating layer 426a, that is, the length of the oxide insulating layer 426b in the cross-sectional view shown in FIG. Edge layer 426a is shown as a trapezoid, and is the length of the base of the trapezoid.

[0058] In the following, Figs. 1(A), 1(B), 1(C), 1(D), and 1(E) will be used to The process of manufacturing the thin film transistor 450 and the thin film transistor 460 on a substrate will be described. .

[0059] First, a conductive film is formed on a substrate 400 having an insulating surface, and then a first photolithography process is performed. Through the process, gate electrode layers 421a and 421b are formed.

[0060] The resist mask may be formed by an ink-jet method. When the film is formed by the jet method, a photomask is not used, and therefore the manufacturing cost can be reduced.

[0061] The conductive film forming the gate electrode layers 421a and 421b may be Al, Cr, Ta, Ti, An element selected from Mo, W, or an alloy containing the above elements, or a combination of the above elements. Examples of such films include alloy films in which a metal oxide is combined with another metal oxide.

[0062] There is no significant limitation on the substrate that can be used for the substrate 400 having an insulating surface. In any case, it is necessary for the insulating surface to have sufficient heat resistance to withstand subsequent heat treatment. The substrate 400 may be a glass substrate.

[0063] In addition, for glass substrates, if the temperature of the subsequent heat treatment is high, the distortion point is 730°C or higher. For the glass substrate, for example, aluminosilicate glass, alumina Glass materials such as lumino borosilicate glass and barium borosilicate glass are used. In addition, by containing more barium oxide (BaO) than boron oxide, it is more practical. Therefore, a glass substrate containing more BaO than B2O3 is used. It is preferable that

[0064] Instead of the above glass substrate, an insulating substrate such as a ceramic substrate, a quartz substrate, or a sapphire substrate may be used. A substrate made of an insulating material may be used. Alternatively, crystallized glass or the like may be used.

[0065] In addition, an insulating film serving as a base film is provided between the substrate 400 and the gate electrode layers 421a and 421b. The undercoat film has a function of preventing diffusion of impurity elements from the substrate 400. A silicon oxide film, a silicon nitride oxide film, or a silicon oxynitride film is used. The insulating film can be formed by a laminate structure.

[0066] Next, a light-transmitting conductive film is formed to cover the gate electrode layers 421a and 421b, and then Gate electrode layers 451a and 451b are formed by a second photolithography process. In the embodiment, in order to reduce the wiring resistance, the gate wiring arranged in the pixel portion is formed on the gate electrode layer. The gate insulating layer 40 is formed from the same metal conductive film as the gate insulating layer 421b. The gate electrode layer 451a overlapping with the gate electrode 451 through the gate electrode 451 is formed using a light-transmitting conductive film.

[0067] Next, a gate insulating layer 402 is formed on the gate electrode layers 421a, 421b, 451a, and 451b. Form.

[0068] The gate insulating layer 402 is a silicon oxide layer formed by using a plasma CVD method, a sputtering method, or the like. A silicon nitride layer, a silicon oxynitride layer, or a silicon nitride oxide layer may be formed as a single layer or a stacked layer. For example, the deposition gas can be SiH4, oxygen, and nitrogen, and the plasma CVD method can be used. The thickness of the gate insulating layer 402 is 100 nm or more and 500 nm or less. In the case of a multilayer structure, the first gate electrode has a thickness of, for example, 50 nm to 200 nm. a gate insulating layer and a second gate insulating layer having a thickness of 5 nm to 300 nm on the first gate insulating layer; The edge layers are laminated.

[0069] In this embodiment, silicon oxynitride (SiON (composition ratio N <O)) The gate insulating layer 402 has a thickness of 100 nm.

[0070] Next, a light-transmitting conductive film is formed over the gate insulating layer 402, and then a third photolithography The source electrode layer 455a and the drain electrode layer 455b are formed by a lithography process. See FIG. 1(A). The light-transmitting conductive film is made of a conductive material that transmits visible light. For example, In-Sn-O system, In-Sn-Zn-O system, In-Al-Zn-O system, Sn- Ga-Zn-O, Al-Ga-Zn-O, Sn-Al-Zn-O, In-Zn-O Metals based on the Sn-Zn-O, Al-Zn-O, In-O, Sn-O, and Zn-O systems An oxide can be used, and the film thickness is appropriately selected within the range of 50 nm to 300 nm. In addition, when the sputtering method is used, a target containing SiO2 in an amount of 2% by weight or more and 10% by weight or less is used. The film is formed using a SiOx (X>0) that inhibits crystallization on the transparent conductive film. This causes crystallization during the heat treatment for dehydration or dehydrogenation in the subsequent process. It is preferable to inhibit the formation of cavities.

[0071] The oxide semiconductor is preferably an oxide semiconductor containing In, more preferably an oxide semiconductor containing In and In order to make the oxide semiconductor layer i-type (intrinsic), Hydrogenation or dehydrogenation is effective.

[0072] Next, the gate insulating layer 402 is selectively etched by a fourth photolithography process. A contact hole reaching gate electrode layer 421b is then formed.

[0073] Next, a film having a thickness of 5 nm to 200 nm, preferably 10 nm, is formed on the gate insulating layer 402. An oxide semiconductor film having a thickness of 20 nm or less is formed. After the oxide semiconductor film is formed, dehydration or Since the oxide semiconductor film is made amorphous even after heat treatment for dehydrogenation, the thickness It is preferable to make the oxide semiconductor film thin, ie, 50 nm or less. When a heat treatment is performed after the formation of the semiconductor layer, crystallization can be suppressed.

[0074] The oxide semiconductor film is an In-Ga-Zn-O non-single crystal film, an In-Sn-Zn-O film, or an In -Al-Zn-O system, Sn-Ga-Zn-O system, Al-Ga-Zn-O system, Sn-Al- Zn-O series, In-Zn-O series, Sn-Zn-O series, Al-Zn-O series, In-O series, S The oxide semiconductor film is a rare gas ( Typically, the mixture is heated under an atmosphere of argon, oxygen, or a rare gas (typically argon) and oxygen. It can be formed by sputtering in a nitrogen atmosphere. In this case, a target containing SiO2 between 2% and 10% by weight is used for deposition, and the oxide is The semiconductor film contains SiOx (X>0), which inhibits crystallization, and is used for dehydration or It is preferable to suppress crystallization during the heat treatment for dehydrogenation.

[0075] Here, an oxide semiconductor target containing In, Ga, and Zn (In2O3:Ga2O 3:ZnO=1:1:1 [molar ratio]) was used, and the distance between the substrate and the target was set at 1 00mm, pressure 0.6Pa, direct current (DC) power supply 0.5kW, oxygen (oxygen flow rate 100% The film is formed under a 100% pure water atmosphere. If a pulsed direct current (DC) power supply is used, dust can be reduced and the film can be formed more efficiently. In this embodiment, the oxide semiconductor film is preferably an In- A 15 nm thick In was deposited by sputtering using a Ga-Zn-O oxide semiconductor target. -Ga-Zn-O based non-single crystal film is formed.

[0076] There are two types of sputtering: RF sputtering, which uses a high-frequency power source for the sputtering power supply, and DC sputtering. There is also the pulsed DC sputtering method, which applies a pulsed bias. The DC sputtering method is mainly used to deposit insulating films, while the DC sputtering method is mainly used to deposit metal conductive films. It is used in such cases.

[0077] There are also multi-target sputtering devices that can accommodate multiple targets of different materials. The equipment can deposit layers of different materials in the same chamber, or multiple types of films in the same chamber. It is also possible to form a film by discharging two or more materials at the same time.

[0078] Also, a sputtering apparatus using a magnetron sputtering method equipped with a magnet mechanism inside the chamber and ECR sputtering using plasma generated by microwaves without glow discharge. There is a sputtering apparatus that uses this method.

[0079] In addition, in a film formation method using a sputtering method, a target material and a sputtering gas component are mixed during film formation. Reactive sputtering is a method of forming thin films of compounds by chemically reacting them with each other, and There is also a bias sputtering method in which a voltage is also applied to the substrate.

[0080] Note that before the oxide semiconductor film is formed by a sputtering method, argon gas is introduced to the plasma The reverse sputtering is performed to generate a dummy mask, and the dust adhering to the surface of the gate insulating layer 402 is removed. In reverse sputtering, the target is sputtered in an argon atmosphere without applying a voltage to the target. A voltage is applied to the substrate side using an RF power source under atmospheric pressure to form plasma near the substrate and modify the surface. It is also possible to use nitrogen, helium, oxygen, etc. instead of the argon atmosphere. good.

[0081] In this embodiment, the gate insulating layer is selectively etched by the fourth photolithography process. A contact hole reaching the gate electrode layer 421b is formed by etching, but this is not particularly limited. After etching the oxide semiconductor film, a resist mask is formed over the oxide semiconductor layer. A contact hole reaching the gate electrode layer 421b may be formed. In that case, The oxide semiconductor layer and the gate insulating layer 402 are removed by etching. It is preferable to remove the above.

[0082] In addition, after an oxide semiconductor film is formed over the gate insulating layer, a resist mask is formed on the oxide semiconductor film. A contact hole reaching the gate electrode layer 421b is formed, and then a resist mask is formed. Then, a resist mask is formed again on the oxide semiconductor film. A step of processing a film into an island-shaped oxide semiconductor layer by selectively etching the film may be performed.

[0083] In addition, before the formation of the oxide semiconductor film, an inert gas atmosphere (nitrogen, helium, neon, Heat treatment (400°C or higher but below the distortion point of the substrate) under argon gas or other gases is then performed to remove the The gate insulating layer may be a gate insulating layer from which impurities such as hydrogen and water have been removed.

[0084] In this embodiment, the gate insulating layer is selectively etched by the fourth photolithography process. In order to form a contact hole reaching the gate electrode layer 421b by etching, After synthesis, the material is heated under an inert gas atmosphere (nitrogen, helium, neon, argon, etc.). Heat treatment (400°C or higher but below the distortion point of the substrate) is performed to remove impurities such as hydrogen and water contained in the layer. After the object is removed, an oxide semiconductor film is preferably formed.

[0085] Next, the oxide semiconductor film is formed into an island-shaped oxide semiconductor layer by a fifth photolithography process. In addition, a resist mask for forming an island-shaped oxide semiconductor layer is formed by inkjet printing. If the resist mask is formed by the ink-jet method, the photomask Since no additional heat is used, the manufacturing costs can be reduced.

[0086] Next, the oxide semiconductor layer is dehydrated or dehydrogenated. The temperature of the heat treatment in step 1 is 400° C. or higher and lower than the distortion point of the substrate, preferably 425° C. or higher. If the temperature is 425℃ or higher, the heat treatment time can be 1 hour or less. The heat treatment time is longer than one hour. The substrate is placed in an electric furnace, and the oxide semiconductor layer is subjected to a heat treatment in a nitrogen atmosphere. After that, the oxide semiconductor layer is not exposed to the air, and impurities such as water and hydrogen are prevented from re-mixing into the oxide semiconductor layer. In this embodiment, the oxide semiconductor layer is dehydrated or dehydrogenated. From the heating temperature T to a temperature that is high enough to prevent water from entering again, use the same furnace. The specimen is cooled slowly in a nitrogen atmosphere until the temperature drops by 100°C below the heating temperature T. Desorption can be performed under an atmosphere of other inert gases (helium, neon, argon, etc.) without limitation. Hydrate or dehydrogenate.

[0087] In the first heat treatment, nitrogen or a rare gas such as helium, neon, or argon is used. It is preferable that the nitrogen introduced into the heat treatment device does not contain water, hydrogen, etc. Or the purity of rare gases such as helium, neon, and argon must be 6N (99.9999%) or higher. Preferably, the concentration of impurities is 7N (99.99999%) or more (i.e., the impurity concentration is 1 ppm or less, It is preferable to keep the concentration of the ion exchange resin at 0.1 ppm or less.

[0088] The conditions of the first heat treatment, the material of the oxide semiconductor film, or the gate electrode layers 451a and 451b can be changed. Depending on the material of 51b, it may crystallize to become a microcrystalline film or a polycrystalline film. After the heat treatment, the oxide semiconductor layers 403 and 453 become oxygen-deficient and have low resistance. (See FIG. 1B.) After the first heat treatment, the oxide semiconductor film has a higher carrier concentration than the oxide semiconductor film immediately after deposition. The degree is increased, preferably by 1×10 18 / cm 3 Oxide semiconductor having a carrier concentration of For example, the gate electrode layers 451a and 451b are made of indium oxide. In the case of using a tin oxide alloy film, the first heat treatment at 450°C for 1 hour crystallizes the film, and the gate voltage is applied. The pole layers 451a and 451b are made of an indium oxide tin oxide alloy film containing silicon oxide. In this case, no crystallization occurs.

[0089] In addition, the first heat treatment of the oxide semiconductor layer is performed on the oxide semiconductor layer before it is processed into the island-shaped oxide semiconductor layer. In this case, the substrate is removed from the heating device after the first heat treatment. It is then taken out and subjected to a fifth photolithography step.

[0090] Next, an oxide semiconductor film was formed on the gate insulating layer 402 and the oxide semiconductor layers 403 and 453 by a sputtering method. After forming the oxide insulating film, a resist mask is formed by a sixth photolithography process. Then, selective etching is performed to form oxide insulating layers 426a and 426b, and then a resist pattern is formed. At this stage, the oxide semiconductor layer has a region in contact with the oxide insulating layer. In this region, a region overlapping the gate electrode layer, the gate insulating layer, and the oxide insulating layer 426a is The oxide insulating layer covering the periphery and side surfaces of the oxide semiconductor layer is a channel formation region. The area overlapping with 426b is also formed. Also, the gate A contact hole reaching the insulating layer 421b and a contact hole reaching the drain electrode layer 455b are formed. Contact holes are also formed.

[0091] The oxide insulating film is at least 1 nm thick and is formed by an oxide insulating method such as a sputtering method. The film can be formed by using an appropriate method that does not allow impurities such as water and hydrogen to be mixed into the film. In the embodiment, a silicon oxide film is formed as the oxide insulating film by a sputtering method. The substrate temperature during the process may be set to room temperature or higher and 300° C. or lower. In this embodiment, the substrate temperature is set to 100° C. The deposition of silicon oxide films by sputtering is carried out under a rare gas (typically argon) atmosphere. The reaction can be carried out in an oxygen atmosphere or in an atmosphere of rare gas (typically argon) and oxygen. In addition, a silicon oxide target or a silicon target is used as the target. For example, a silicon target can be used for sputtering in an oxygen and rare gas atmosphere. Silicon oxide can be formed by a ring method. The oxide insulating film formed is resistant to moisture, hydrogen ions, and OH - It does not contain impurities such as An inorganic insulating film is used to block the intrusion of A silicon oxide film, an aluminum oxide film, an aluminum oxynitride film, or the like is used.

[0092] In this embodiment, a columnar polycrystalline B-doped silicon target (resistance value 0 The distance between the substrate and the target (TS distance) was 89 mm, and the pressure was 1.01 Ωcm. Pulse was measured under an oxygen atmosphere (oxygen flow rate 100%) with a pressure of 0.4 Pa and a direct current (DC) power of 6 kW. The film is formed by DC sputtering. The film thickness is 300 nm.

[0093] Next, a second heat treatment (preferably a second heat treatment) is performed under an inert gas atmosphere or a nitrogen gas atmosphere. The heating is performed at a temperature of from 00° C. to 400° C., for example from 250° C. to 350° C. (see FIG. 1(C)). For example, the second heat treatment is performed at 250° C. for 1 hour in a nitrogen atmosphere. As a result, an end portion of the oxide semiconductor layer 403 overlapping with the oxide insulating layer 426b and an oxide insulating layer A part of the oxide semiconductor layer 403 overlapping with the oxide insulating layer 426a is heated in the state of being in contact with the oxide insulating layer. Note that when the second heat treatment is performed, part of the oxide semiconductor layer that does not overlap with the oxide insulating layer is exposed. The oxide semiconductor layer 403 is exposed. When the heat treatment is performed in an active gas atmosphere, the exposed portion of the oxide semiconductor layer becomes highly resistive. The oxide insulating layer 426a can have low resistance. A channel protection layer is provided on and in contact with a region that is to be a channel formation region of the oxide semiconductor layer. It works like this.

[0094] The second heat treatment is performed immediately after the sixth photolithography process. There is no particular limitation as long as it is a process subsequent to the sixth photolithography process.

[0095] Next, the gate insulating layer 402, the oxide insulating layers 426a and 426b, and the oxide semiconductor layer are After forming a conductive film, a resist mask is formed by a seventh photolithography process. Then, selective etching is performed to form a source electrode layer 425a and a drain electrode layer 425b. As shown in FIG. 1D, the gate electrode layer 421b is A connection electrode layer 429 electrically connected to the drain electrode layer 455b An electrode layer 452 is also formed. The conductive film is formed by sputtering or vacuum deposition (electron beam evaporation). The conductive film is made by the arc discharge ion plating method or the spray method. The elements are selected from Ti, Mo, W, Al, Cr, Cu, Ta, or the above-mentioned elements. The conductive film is an alloy containing the above elements or an alloy combining the above elements. The present invention is not limited to a single layer containing the element, but may be a stack of two or more layers. The titanium film (thickness 100 nm), the aluminum film (thickness 200 nm), and the titanium film (thickness A three-layer conductive film with a thickness of 100 nm is formed. In addition, a titanium nitride film is used instead of the Ti film. This is also fine.

[0096] In the seventh photolithography step, only the conductive film in contact with the oxide semiconductor layer is Therefore, only the conductive film in contact with the oxide semiconductor layer is selectively removed. To remove the ions, an alkaline etchant, ammonia hydrogen peroxide (ammonia hydrogen peroxide solution), was used. By using a 5:2:2 humidifier, the conductive film can be selectively removed to produce In-Ga-Z The oxide semiconductor layer made of the nO-based oxide semiconductor can be left.

[0097] Note that a resist mask for forming the source electrode layer 425a and the drain electrode layer 425b is used. The resist mask may be formed by an inkjet method. Since no photomask is used, manufacturing costs can be reduced.

[0098] Next, the oxide insulating layers 426a and 426b, the source electrode layer 425a, and the drain electrode layer 42 5b, an insulating layer 428 is formed on the connection electrode layer 429 and the connection electrode layer 452 (FIG. 1(E The insulating layer 428 may be a silicon nitride film, a silicon nitride oxide film, or an aluminum nitride film. In this embodiment, the insulating layer 4 of a silicon nitride film is formed by RF sputtering. Form 28.

[0099] Through the above process, two types of thin-film transistors, a channel-protected thin-film transistor, and a A bottom-contact type thin film transistor 450 and a bottom-contact type thin film transistor 460 can be fabricated. .

[0100] The channel protection type thin film transistor 450 has a channel length L of a channel forming region of 0.1 μm. The width of the oxide insulating layer is narrowed to 2 μm or more, and the thin-film transistor with high operating speed is The bottom-contact thin film transistor 460 has a channel length of However, the thin film transistor 450 is longer than the channel protection type thin film transistor 450 and has a reduced off-current. The bottom contact type thin film transistor 460 is a connection The layers other than the pole layer 452 are made of a material having light transmitting properties.

[0101] When manufacturing a light-emitting device, multiple thin film transistors are arranged in one pixel. The driving TFT electrically connected to the optical element has a channel length L of 55 μm and a channel width W of 2 The selection TFT, which is electrically connected to the gate electrode layer of the driving TFT, has a channel The length L is 25 μm and the channel width W is 60 μm. The source electrode layer in the channel length direction The overlap width between the drain electrode layer and the gate electrode layer is 5 μm. The overlap width of the polar layers is 5 μm. The bottom contacts are used as the driving TFT and the selection TFT. The structure of the thin film transistor 460 is used.

[0102] In addition, when manufacturing a light-emitting device, a power supply that is electrically connected to the source electrode layer of the driving TFT is A power supply line is provided, the power supply line intersecting the gate wiring and a connection electrode layer made of a conductive film. The power supply line is formed of the same material and in the same process as 429. Alternatively, the power supply line crosses the source wiring, In addition, the gate electrode layer 421b is formed of the same material and in the same process as the gate electrode layer 421b.

[0103] In addition, when a light emitting device is manufactured, one electrode of the light emitting element is the drain electrode layer of the driving TFT. and a common potential line electrically connected to the other electrode of the light emitting element. The common potential line is made of the same material and formed in the same process as the connection electrode layer 429 made of a conductive film. Alternatively, the common potential line is formed of the same material and in the same process as the gate electrode layer 421b. .

[0104] In addition, when a light-emitting device is manufactured, one pixel has a plurality of thin film transistors. Connect the gate electrode layer of one thin film transistor to the drain electrode layer of another thin film transistor The connection portion is electrically connected to the gate electrode layer 421b. It is formed in the same process as the electrode layer 429 .

[0105] In addition, when forming a driving circuit on the same substrate, for example, a channel protection type thin film transistor The channel length L is 2 μm and the channel width W is 50 μm. The width of the third region and the width of the fourth region in the channel length direction are each 2 μm. The overlap width between the source electrode layer and the gate electrode layer is set to 2 μm, and the drain potential in the channel length direction is set to The overlap width between the electrode layer and the gate electrode layer is set to 2 μm.

[0106] A plurality of types of circuits, a driver circuit and a pixel portion in this embodiment mode, are formed on the same substrate. Depending on the characteristics of the element, a channel protection type thin film transistor 450 or a bottom Optimization can be achieved by using a contact-type thin film transistor 460. .

[0107] (Embodiment 2) In this embodiment, a plurality of thin film transistors shown in Embodiment 1 and an electroluminescent An active matrix type light emitting display device is manufactured by using a light emitting element that utilizes a light emitting diode. Here is an example.

[0108] Light-emitting elements that utilize electroluminescence are characterized by the fact that the light-emitting material is either an organic compound or an inorganic compound. Generally, the former are organic EL elements and the latter are inorganic EL elements. It is called.

[0109] 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.

[0110] 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.

[0111] FIG. 2 shows an example of a pixel configuration to which digital time gray scale driving can be applied as an example of a semiconductor device. FIG.

[0112] 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 figure shows an n-channel transistor that uses an oxide semiconductor layer as a channel formation region in one pixel. Here is an example of using two of them.

[0113] 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. It is electrically connected to a common potential line formed on the substrate.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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. 2 can be used.

[0118] 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 plus 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 light emitting element 6403. Analog gradation drive can be performed by passing a current corresponding to a video signal through 6404.

[0119] Note that the pixel configuration shown in FIG. 2 is not limited to this. For example, if a new switch is added to the pixel shown in FIG. A switch, a resistive element, a capacitive element, a transistor, a logic circuit, or the like may be added.

[0120] Next, the configuration of the light-emitting element will be described with reference to FIG. 3. Here, the driving TFT is an n-type The cross-sectional structure of the pixel will be explained using the semiconductor device shown in FIG. The driving TFTs TFT7001, 7011, and 7021 used in the device are It can be manufactured in the same manner as the thin film transistor shown in Form 1, and is a highly reliable thin film including an oxide semiconductor layer. It is a membrane transistor.

[0121] 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. The structure has a top emission structure that emits light from the top surface of the substrate, a bottom emission structure that emits light from the bottom surface of the substrate, and a structure that emits light from the bottom surface of the substrate and the bottom surface of the substrate. There are also light-emitting elements with a double-sided emission structure in which light is emitted from the opposite side of the pixel. The above can be applied to any light emitting device with any emission structure.

[0122] A light emitting element having a bottom emission structure will be described with reference to FIG.

[0123] The driving TFT 7011 is an n-type TFT, and light emitted from the light emitting element 7012 is incident on the cathode 7013 side. FIG. 3(A) shows a cross-sectional view of a pixel when emitting light. A light-emitting element is disposed on a light-transmitting conductive film 7017 electrically connected via an electrode layer 7030. A cathode 7013 of 7012 is formed, an EL layer 7014 is formed on the cathode 7013, and an anode 70 The connection electrode layer 7030 is formed on the oxide insulating layer 7031. The drain electrode layer of the driving TFT 7011 is electrically connected to the drain electrode layer of the driving TFT 7011 through a contact hole. It is being done.

[0124] The light-transmitting conductive film 7017 can be formed of indium oxide containing tungsten oxide, oxide Indium zinc oxide with tungsten oxide, indium oxide with titanium oxide, Indium tin oxide containing titanium, indium tin oxide, indium zinc oxide, oxide carbide A light-transmitting conductive film such as indium tin oxide to which indium is added can be used. Cut.

[0125] In addition, the cathode 7013 can be made of various materials. However, it is preferable to use a material having a small work function, e.g. For example, alkali metals such as Li and Cs, and alkaline earth metals such as Mg, Ca, and Sr, and alloys containing these (Mg:Ag, Al:Li, etc.), as well as rare earth metals such as Yb and Er. In FIG. 3(A), the thickness of the cathode 7013 is set to a thickness that allows light to pass through (preferably, For example, an aluminum film having a thickness of 20 nm is used as the cathode. Used as 7013.

[0126] After a light-transmitting conductive film and an aluminum film are laminated, the film is selectively etched. In this case, the conductive film 7017 and the cathode 7013 may be formed on the same substrate. It is preferable to use a etchant.

[0127] The periphery of the cathode 7013 is covered with a partition wall 7019. The partition wall 7019 is made of polyimide, alumina, Organic resin films such as acrylic, polyamide, and epoxy, inorganic insulating films, and organic polysiloxanes The partition wall 7019 is formed by using a photosensitive resin material and has an opening on the cathode 7013. The side wall of the opening is shaped to have a slope with a continuous curvature. When a photosensitive resin material is used for the partition wall 7019, a resist mask is preferably used. Therefore, the step of forming a mask can be omitted.

[0128] The EL layer 7014 formed on the cathode 7013 and the partition wall 7019 is composed of a single layer. The EL layer 70 may be formed by laminating a plurality of layers. When the cathode 7013 is composed of a plurality of layers, an electron injection layer, an electron transport layer, a light emitting layer, and a The layer, the hole transport layer, and the hole injection layer are laminated in this order. Note that it is not necessary to provide all of these layers. stomach.

[0129] The stacking order is not limited to the above, and may be a hole injection layer, a hole transport layer, a light emitting layer, etc., on the cathode 7013. However, when comparing power consumption, the cathode may be used in the same manner as the cathode. An electron injection layer, an electron transport layer, a light-emitting layer, a hole transport layer, and a hole injection layer are stacked on the electrode 7013 in this order. Layering is preferred because it consumes less power.

[0130] In addition, various materials can be used for the anode 7015 formed on the EL layer 7014. However, materials with large work functions, such as ZrN, Ti, W, Ni, Pt, Cr, etc., and I Transparent conductive materials such as TO, IZO, and ZnO are preferred. 7016, for example, a metal that blocks light, a metal that reflects light, etc. are used. An ITO film is used as the anode 7015 , and a Ti film is used as the shielding film 7016 .

[0131] 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 element structure shown in FIG. 3A, the light emitted from the light-emitting element 7012 is , and is emitted toward the cathode 7013 as indicated by the arrow.

[0132] Note that FIG. 3A shows an example in which a light-transmitting conductive film is used as a gate electrode layer. The light emitted from the light emitting element 7012 passes through the color filter layer 7033 and is reflected by the thin film transistor 7034. The light is emitted through the gate electrode layer and source electrode layer of the thin-film transistor 7011. A conductive film having a light-transmitting property is used as the gate electrode layer and the source electrode layer of the FET 7011, and the aperture ratio is It can be improved.

[0133] The color filter layer 7033 is formed by a droplet discharge method such as an inkjet method, a printing method, a photolithography method, or the like. Each is formed by an etching method using graphic technology.

[0134] The color filter layer 7033 is covered with an overcoat layer 7034, which is a protective insulating layer. In FIG. 3A, the overcoat layer 7034 is thin. As shown in the figure, the overcoat layer 7034 covers the unevenness caused by the color filter layer 7033. It has a flattening function.

[0135] In addition, a protective insulating layer 7035 and an insulating layer 7032 are formed on the connecting electrode layer 7030. The contact hole is disposed at a position overlapping with a partition wall 7019. Since the connecting electrode layer 7030 is an example using a metal conductive film, The layout is such that the contact hole, the partition wall 7019, and the connection electrode layer 7030 are overlapped. This makes it possible to improve the aperture ratio.

[0136] Next, a light emitting element having a dual emission structure will be described with reference to FIG.

[0137] In FIG. 3B, the driving TFT 7021 is electrically connected to the connection electrode layer 7040. A cathode 7023 of a light-emitting element 7022 is formed over the light-transmitting conductive film 7027. An EL layer 7024 and an anode 7025 are laminated in this order on the cathode 7023. The electrode layer 7040 is connected to the driving T through a contact hole formed in the oxide insulating layer 7041. It is electrically connected to the drain electrode layer of the FT7021.

[0138] The light-transmitting conductive film 7027 can be formed using indium oxide containing tungsten oxide, Indium zinc oxide with tungsten oxide, indium oxide with titanium oxide, Indium tin oxide containing titanium, indium tin oxide, indium zinc oxide, oxide carbide A light-transmitting conductive film such as indium tin oxide to which indium is added can be used. Cut.

[0139] In addition, the cathode 7023 can be made of various materials. However, it is preferable to use a material with a small work function, e.g. For example, alkali metals such as Li and Cs, and alkaline earth metals such as Mg, Ca, and Sr, and alloys containing these (Mg:Ag, Al:Li, etc.), as well as rare earth metals such as Yb and Er. In this embodiment, the thickness of the cathode 7023 is set to a thickness that allows light to pass through (preferably For example, an aluminum film having a thickness of 20 nm is Used as pole 7023.

[0140] After a light-transmitting conductive film and an aluminum film are laminated, the film is selectively etched. In this case, the conductive film 7027 and the cathode 7023 may be formed on the same substrate. It is preferable to use a etchant.

[0141] The periphery of the cathode 7023 is covered with a partition 7029. The partition 7029 is made of polyimide, alumina, Organic resin films such as acrylic, polyamide, and epoxy, inorganic insulating films, and organic polysiloxanes The partition wall 7029 is formed by using a photosensitive resin material and has an opening on the cathode 7023. The side wall of the opening is shaped to have a slope with a continuous curvature. When a photosensitive resin material is used for the partition 7029, a resist mask is preferably used. Therefore, the step of forming a mask can be omitted.

[0142] The EL layer 7024 formed on the cathode 7023 and the partition wall 7029 is composed of a single layer. The EL layer 70 may be formed by laminating a plurality of layers. When the cathode 7023 is composed of a plurality of layers, an electron injection layer, an electron transport layer, a light emitting layer, and a The layer, the hole transport layer, and the hole injection layer are laminated in this order. Note that it is not necessary to provide all of these layers. stomach.

[0143] The stacking order is not limited to the above, and may be a hole injection layer, a hole transport layer, a light emitting layer, etc., on the cathode 7023. However, when comparing power consumption, the cathode may be used in the same manner as the cathode. An electron injection layer, an electron transport layer, a light-emitting layer, a hole transport layer, and a hole injection layer are stacked on the electrode 7023 in this order. Layering is preferred because it consumes less power.

[0144] In addition, various materials can be used for the anode 7025 formed on the EL layer 7024. However, materials with large work functions, such as transparent conductive materials such as ITO, IZO, and ZnO, are In this embodiment, an ITO film containing silicon oxide is used as the anode 7025.

[0145] The region where the light-emitting layer 7024 is sandwiched between the cathode 7023 and the anode 7025 is the light-emitting element 7022. In the case of the element structure shown in FIG. 3B, the light emitted from the light-emitting element 7022 is , and is emitted toward both the anode 7025 side and the cathode 7023 side as indicated by the arrows.

[0146] Note that FIG. 3B shows an example in which a light-transmitting conductive film is used as the gate electrode layer. The light emitted from the light emitting element 7022 to the cathode 7023 passes through the color filter layer 7043. Then, the light passes through the gate electrode layer and the source electrode layer of the thin film transistor 7021 and is emitted. A light-transmitting conductive film as a gate electrode layer or a source electrode layer of the thin film transistor 7021. By using this, the aperture ratio on the anode 7025 side and the aperture ratio on the cathode 7023 side can be made almost the same. This can be done.

[0147] The color filter layer 7043 is formed by a droplet discharge method such as an inkjet method, a printing method, a photolithography method, or the like. Each is formed by an etching method using graphic technology.

[0148] The color filter layer 7043 is covered with an overcoat layer 7044, which is a protective insulating layer. Covered by layer 7045 .

[0149] In addition, a protective insulating layer 7045 and an insulating layer 7042 are formed on the connecting electrode layer 7040. The contact hole is arranged at a position overlapping with a partition wall 7029. Since the connecting electrode layer 7040 is an example using a metal conductive film, The layout is such that the contact hole, the partition wall 7029, and the connection electrode layer 7040 are overlapped. In this way, the aperture ratio on the anode 7025 side and the aperture ratio on the cathode 7023 side can be made substantially the same.

[0150] However, when using a light-emitting element with a dual-side emission structure and making both display surfaces full color display, Since the light from the anode 7025 side does not pass through the color filter layer 7043, a separate color filter is required. It is preferable to provide a sealing substrate having a filter layer above the anode 7025.

[0151] Next, a light emitting element having a top emission structure will be described with reference to FIG.

[0152] In FIG. 3C, a TFT 7001 which is a driving TFT is an n-type TFT, and light emitted from a light-emitting element 7002 is FIG. 3C shows a cross-sectional view of a pixel in the case where the light entering the pixel exits the anode 7005 side. A light-emitting element 7002 electrically connected to a TFT 7001 for use via a connection electrode layer 7050. A cathode 7003 is formed, and an EL layer 7004 and an anode 7005 are formed on the cathode 7003 in this order. It is layered.

[0153] In addition, the cathode 7003 can be made of various materials. However, it is preferable to use a material with a small work function, e.g. Specifically, alkali metals such as Li and Cs, and alkaline earths such as Mg, Ca, and Sr. In addition to metals and alloys containing these (Mg:Ag, Al:Li, etc.), Yb, Er, etc. Rare earth metals and the like are preferred.

[0154] The periphery of the cathode 7003 is covered with a partition wall 7009. The partition wall 7009 is made of polyimide, alumina, Organic resin films such as acrylic, polyamide, and epoxy, inorganic insulating films, and organic polysiloxanes The partition wall 7009 is formed by using a photosensitive resin material and has an opening on the cathode 7003. The side wall of the opening is shaped to have a slope with a continuous curvature. When a photosensitive resin material is used for the partition wall 7009, Therefore, the step of forming a mask can be omitted.

[0155] In addition, the EL layer 7004 formed on the cathode 7003 and the partition wall 7009 is composed of a single layer. The EL layer 70 may be formed by laminating a plurality of layers. When the cathode 7003 is composed of multiple layers, an electron injection layer, an electron transport layer, a light emitting layer, and a The layer, the hole transport layer, and the hole injection layer are laminated in this order. Note that it is not necessary to provide all of these layers. stomach.

[0156] The stacking order is not limited to the above, and a hole injection layer, a hole transport layer, and a light emitting layer may be stacked on the cathode 7003. The cathode 700 may be laminated in this order, the electron transport layer, and the electron injection layer. 3 will function as the anode.

[0157] In Figure 3(C), holes are injected onto a laminated film consisting of a Ti film, an aluminum film, and a Ti film. A hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer are laminated in that order, and then a Mg:Ag A laminate of an alloy thin film and ITO is formed.

[0158] However, when comparing power consumption, the cathode 7003 is provided with an electron injection layer, an electron transport layer, a light emitting layer, It is preferable to laminate the hole transport layer and the hole injection layer in this order, since this reduces power consumption.

[0159] The anode 7005 is formed using a conductive material that transmits light, such as titanium oxide. Indium oxide with tungsten oxide, indium zinc oxide with tungsten oxide, Indium oxide containing titanium, indium tin oxide containing titanium oxide, indium stannate Indium tin oxide with added silicon oxide, indium zinc oxide, Alternatively, a conductive film having a conductive property may be used.

[0160] 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. 3C, light emitted from the light-emitting element 7002 is The light is emitted toward the anode 7005 as shown in FIG.

[0161] In FIG. 3C, a TFT 7001 is an example in which a thin film transistor 460 is used. However, there is no particular limitation, and a thin film transistor 450 can be used. When a thin film transistor 450 is used as the thin film transistor 01, the cathode 7003 and the drain electrode layer are connected. The electrodes are electrically connected so as to

[0162] In FIG. 3C, the drain electrode layer of the TFT 7001 is connected to the connection electrode layer 7050. The connection electrode layer 7050 is electrically connected via the oxide insulating layer 7051. 52 and the cathode 7003 via the insulating layer 7055. 3. Resin materials such as polyimide, acrylic, benzocyclobutene, polyamide, and epoxy In addition to the above resin materials, low-k materials, silicon materials, etc. can be used. Use oxyxane resin, PSG (phosphorus glass), BPSG (borophosphorus glass), etc. In addition, by stacking multiple insulating films made of these materials, a flat insulating film can be obtained. The method for forming the planarization insulating layer 7053 is not particularly limited, and Depending on the material, sputtering, SOG, spin coating, dip, spray coating, droplet ejection Printing method (inkjet method, screen printing, offset printing, etc.), doctor knife, A roll coater, curtain coater, knife coater, etc. can be used.

[0163] In addition, a partition wall 7009 is provided to insulate the cathode 7003 from the cathode 7008 of the adjacent pixel. The partition wall 7009 is an organic resin film such as polyimide, acrylic, polyamide, or epoxy. The partition wall 7009 is formed using an inorganic insulating film or an organic polysiloxane. An opening is formed on the cathode 7003 using the resin material, and the side wall of the opening has a continuous curvature. It is preferable to form the partition wall 7009 so as to have an inclined surface having a slope. When a photosensitive resin material is used, the step of forming a resist mask can be omitted.

[0164] In the structure of FIG. 3C, when a full-color display is performed, for example, the light-emitting element 700 The first light-emitting element is a green light-emitting element, the second light-emitting element is a red light-emitting element, and the third light-emitting element is a red light-emitting element. The light elements are blue light emitting elements. In addition to the three types of light emitting elements, a white element is added, making a total of four types. A light-emitting display device capable of full color display may be manufactured using such light-emitting elements.

[0165] In the structure of FIG. 3C, all the light emitting elements are white light emitting elements. A sealing substrate having a color filter or the like is disposed above the light emitting element 7002. A light-emitting display device capable of displaying multiple colors may be manufactured. By forming a color filter and combining it with a color conversion layer, a full color display can be achieved. This can be done.

[0166] Of course, a single-color display may be used. For example, a lighting device may be formed using white light. Alternatively, monochromatic light may be used to form an area color type light emitting device.

[0167] If necessary, an optical film such as a polarizing film, eg, a circular polarizing plate, may be provided.

[0168] 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.

[0169] In addition, the thin film transistor (driving TFT) that controls the driving of the light-emitting element and the light-emitting element are electrically However, a current control TFT is connected between the driving TFT and the light emitting element. The configuration may be such that the input / output terminals are connected to each other.

[0170] (Embodiment 3) In this embodiment mode, a plurality of thin film transistors shown in Embodiment Mode 1 are used to form a single semiconductor device on the same substrate. An example of forming a pixel portion and a driver circuit in an active matrix type light emitting display device is shown below. show.

[0171] In the first embodiment, two thin film transistors and a cross section of a connection portion are illustrated. In the embodiment, a wiring intersection and a capacitance portion are also illustrated and described.

[0172] FIG. 4 is a cross-sectional view showing the state of the substrate before an EL layer is formed on a first electrode (pixel electrode). In addition, the same reference numerals are used for the same parts as in FIG.

[0173] In FIG. 4, the driving TFT electrically connected to the first electrode 457 is a bottom contact type. The thin film transistor 460 is manufactured according to the method of the first embodiment. This can be done.

[0174] After forming the insulating layer 428 according to the first embodiment, a green color filter layer 456, a blue A color filter layer of red, a color filter layer of red, and a color filter layer of red are sequentially formed. Printing, inkjet printing, photolithography, and other etching methods are used. By providing a color filter layer, the accuracy of lamination of the sealing substrate is improved. The color filter layer and the light-emitting region of the light-emitting element can be aligned without the need for a do.

[0175] Next, a green color filter layer 456, a blue color filter layer, and a red color filter layer are An overcoat layer 458 is formed to cover the filter layer. The overcoat layer 458 has a light-transmitting property. A resin having such properties is used.

[0176] Here, an example of full color display using three colors of RGB is shown, but there is no particular limitation. A full color display may be performed using the four colors of BW.

[0177] Next, a protective insulating layer 413 is formed to cover the overcoat layer 458 and the insulating layer 428 . The protective insulating layer 413 is made of an inorganic insulating film, such as a silicon nitride film, an aluminum nitride film, or a nitride film. A silicon oxide film, an aluminum oxynitride film, or the like is used as the protective insulating layer 413. If the insulating film has the same composition as the layer 428, the contact holes can be formed in a single process. This is preferable because it allows for easy switching.

[0178] Next, the protective insulating layer 413 and the insulating layer 428 are selectively etched by a photolithography process. A contact hole reaching the connection electrode layer 452 is formed by etching. The protective insulating layer 413 and the insulating layer 428 of the terminal portion are selectively etched by a lithography process. The terminal electrode is then partially exposed. The second electrode and the common electrode of the light emitting element to be formed later are also formed. In order to connect to the potential line, a contact hole reaching the common potential line is also formed.

[0179] Next, a light-transmitting conductive film is formed, and a connection electrode layer 45 is formed by a photolithography process. 2 is formed.

[0180] Next, a partition wall 459 is formed so as to cover the periphery of the first electrode 457. organic resin films such as polyimide, acrylic, polyamide, and epoxy; inorganic insulating films or organic poly The partition wall 459 is formed by using a photosensitive resin material. 57, and an opening is formed on the surface of the substrate 10, and the side wall of the opening is an inclined surface having a continuous curvature. When a photosensitive resin material is used for the partition wall 459, a resist mask is formed. The step of forming the insulating film can be omitted.

[0181] Through the above steps, the substrate state shown in FIG. 4 can be obtained. The following steps are the same as those in the second embodiment. As shown in FIG. 1, an EL layer is formed on the first electrode 457, and a second electrode is formed on the EL layer. The second electrode is electrically connected to a common potential line.

[0182] In addition, a capacitance section is formed in the pixel section as shown in FIG. The gate insulating layer 402 serves as a dielectric, and the capacitor is formed of a capacitor wiring layer 430 and a capacitor electrode layer 431 . In the light emitting device, the capacitance wiring layer 430 is a part of the power supply line, and the capacitance electrode layer 4 Reference numeral 31 denotes a part of the gate electrode layer of the driving TFT.

[0183] In addition, in order to reduce parasitic capacitance at the wiring intersections as shown in FIG. Between the gate insulating layer 402 and the source wiring layer 422, the gate insulating layer 402 and the oxide insulating layer 426b are provided. In addition, in FIG. 4, the gate wiring layer 421c is a metal conductive film. However, the conductive layer 451a has the same light-transmitting property as the gate electrode layer 451a of the thin film transistor 460. It can also be formed using a film.

[0184] In addition, in FIG. 4, the TFT arranged in the driving circuit is a channel protection type thin film transistor. 450, and in this embodiment, it can be manufactured according to the first embodiment.

[0185] In addition, in FIG. 4, at least one TFT disposed in the driving circuit is a thin film transistor. 450, and in this embodiment, it can be manufactured according to the first embodiment.

[0186] In addition, a conductive layer 417 is provided above the oxide semiconductor layer of the thin film transistor 450 of the driver circuit. The conductive layer 417 may be formed of the same material and in the same process as the first electrode 457. do.

[0187] The conductive layer 417 is provided so as to overlap with the channel formation region 423 of the oxide semiconductor layer. The bias-thermal stress test (BT) is used to check the reliability of thin-film transistors. In the test, the threshold voltage of the thin film transistor 450 before and after the BT test was In addition, the conductive layer 417 has a potential different from that of the gate electrode layer 421a. It may be the same or different and may function as a second gate electrode layer. The potential of the conductive layer 417 may be GND, 0 V, or may be in a floating state. stomach.

[0188] In addition, thin film transistors are easily damaged by static electricity, etc. The protection circuit is preferably provided over the same substrate as the semiconductor device. It is preferable to use a nonlinear element. For example, the protection circuit is In this embodiment, a plurality of protection circuits are provided between the terminal and the signal line input terminal. A surge voltage is applied to the scanning lines, signal lines and capacitance bus lines due to static electricity or the like, and the pixel transistors are The protection circuit is designed to prevent the transistors from being destroyed. When a voltage is applied, the protection circuit is configured to release the electric charge to the common wiring. The nonlinear element is arranged in parallel with the scanning line. It is composed of a two-terminal element such as an electrode or a three-terminal element such as a transistor. For example, It is possible to form the thin film transistor 460 in the pixel portion in the same process. For example, By connecting the drain terminal to the terminal, it can have the same characteristics as a diode. do.

[0189] This embodiment mode can be freely combined with embodiment mode 1 or 2.

[0190] (Embodiment 4) In this embodiment, one of the configurations of the terminal portion provided on the same substrate as the thin film transistor is An example is shown in Fig. 5. In Fig. 5, the same parts as in Fig. 4 are described using the same reference numerals.

[0191] FIG. 5(A1) and FIG. 5(A2) are a cross-sectional view and a top view, respectively, of a gate line terminal portion. FIG. 5(A1) corresponds to a cross-sectional view taken along line C1-C2 in FIG. 5(A2). In (A1), a conductive layer 415 is formed on a laminate of an insulating layer 428 and a protective insulating layer 413. is a terminal electrode for connection that functions as an input terminal. In the sub-portion, a first terminal 411 made of the same material as the gate wiring layer 421c and a source wiring The line layer 422 and the connection electrode layer 412 made of the same material are overlapped with each other via the gate insulating layer 402. The conductive layer 415 is electrically connected to the first electrode 457. The optical material can be formed in the same process.

[0192] FIG. 5(B1) and FIG. 5(B2) are a cross-sectional view and a top view of a source wiring terminal portion, respectively. FIG. 5(B1) is a cross-sectional view taken along line C3-C4 in FIG. 5(B2). In FIG. 5B1, a layer formed over the insulating layer 428 and the protective insulating layer 413 corresponds to the insulating layer 428. The conductive layer 418 is a terminal electrode for connection that functions as an input terminal. In 1), the electrode layer 416 is made of the same material as the gate wiring layer 421c in the terminal portion. However, the second terminal 414 is electrically connected to the source line through the gate insulating layer 402. The electrode layer 416 is not electrically connected to the second terminal 414, and the electrode layer 41 6 is set to a potential different from that of the second terminal 414, for example, floating, GND, 0V, etc. In this way, a capacitance for noise countermeasures or a capacitance for static electricity countermeasures can be formed. The second terminal 414 is connected to the conductive layer 418 via the insulating layer 428 and the protective insulating layer 413. The conductive layer 418 is electrically connected to the first electrode 457. The materials can be formed in the same process.

[0193] A plurality of gate lines, source lines, common potential lines, and power supply lines are provided according to the pixel density. In addition, in the terminal section, a first terminal having the same potential as the gate wiring, a source wiring a second terminal at the same potential as the line; a third terminal at the same potential as the power supply line; and a fourth terminal at the same potential as the common potential line. The number of each terminal can be set to any number. This is acceptable, and the implementer can make the appropriate decision.

[0194] This embodiment can be freely combined with embodiment 1, embodiment 2, or embodiment 3. It is possible.

[0195] (Embodiment 5) In this embodiment mode, the light-emitting element used in FIGS. 3(A) and 3(C) shown in Embodiment 2 is An example of the element structure will be described.

[0196] The element structure shown in FIG. 6A includes a pair of electrodes (a first electrode 1001 and a second electrode 1002). The EL layer 1003 including the light-emitting region is sandwiched between the first and second electrodes. In the description, the first electrode 1001 is used as an anode, and the second electrode 100 2 shall be used as the cathode.

[0197] The EL layer 1003 is sufficient as long as it includes at least a light-emitting layer. The functional layer other than the light-emitting layer may be a layer structure including a functional layer having a high hole injection property. materials with high hole transport properties, materials with high electron transport properties, materials with high electron injection properties, A layer containing a material having a high electron and hole transporting property can be used. Specifically, functional layers such as a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer are appropriately combined. It can be used in combination.

[0198] The light-emitting element shown in FIG. 6A has a first electrode 1001 and a second electrode 1002. The potential difference causes a current to flow, and holes and electrons recombine in the EL layer 1003, emitting light. In other words, the EL layer 1003 is configured to form a light-emitting region.

[0199] Light is emitted through either the first electrode 1001 or the second electrode 1002, or both. Therefore, the electric current is taken out to the outside through either the first electrode 1001 or the second electrode 1002. Either or both of the first and second electrodes are made of a material having optical transparency.

[0200] As shown in FIG. 6B, the EL layer is formed between the first electrode 1001 and the second electrode 1002. In the case of a laminated structure of n layers (n is a natural number of 2 or more), A charge generating layer 1004 is provided between the (m+1)th EL layer and the (m+2)th EL layer. Here, m is a natural number and is equal to or greater than 1 and equal to or less than (n-1).

[0201] The charge generating layer 1004 is a composite material of an organic compound and a metal oxide, a metal oxide, an organic compound, Alkali metals, alkaline earth metals, or composite materials with these compounds, as well as The composite material of an organic compound and a metal oxide can be formed by appropriately combining them. Examples include organic compounds and metal oxides such as V2O5, MoO3, and WO3. The following compounds are considered to be suitable for use: aromatic amine compounds, carbazole derivatives, aromatic hydrocarbons, polymer compounds (oligosaccharides, etc.) Various compounds such as carboxymers, dendrimers, polymers, etc. can be used. As an organic compound, a hole-transporting organic compound with a hole mobility of 10 -6 cm 2 / Vs or later However, it is preferable that the material has a higher hole transporting property than the electron transporting property. If desired, materials other than these may be used. The material has excellent carrier injection and carrier transport properties, enabling low current operation of light-emitting devices. It is possible.

[0202] The charge generating layer 1004 is made of a composite material of an organic compound and a metal oxide, and other materials. For example, a layer including a composite material of an organic compound and a metal oxide and a layer including an electron transport layer may be formed. A compound selected from among the electroconductive materials and a layer containing a compound having high electron transport properties are combined. Alternatively, a layer containing a composite material of an organic compound and a metal oxide and a transparent conductive film may be combined. may be formed in combination with each other.

[0203] A light-emitting element having such a configuration is less susceptible to problems such as energy transfer and quenching. By expanding the range of materials to be selected, it will be possible to develop light-emitting devices that have both high luminous efficiency and a long lifespan. It is also easy to obtain phosphorescence in one EL layer and fluorescence in the other. .

[0204] The charge generating layer 1004 is a layer that generates a charge when a voltage is applied between the first electrode 1001 and the second electrode 1002. When the charge generating layer 1004 is turned on, holes are generated in the EL layer 1003 formed in contact with the charge generating layer 1004. The EL layer 1002 has a function of injecting electrons into the other EL layer 1003 .

[0205] The light-emitting element shown in FIG. 6B can be used in various ways by changing the type of light-emitting material used in the light-emitting layer. In addition, it is possible to obtain a variety of luminescent colors by using multiple luminescent materials with different luminescent colors. This makes it possible to obtain light emission with a broad spectrum or white light emission.

[0206] When white light is obtained using the light-emitting element shown in FIG. 6B, a combination of a plurality of light-emitting layers is used. The light source may be configured to emit white light containing red, blue, and green light. For example, The first EL layer contains fluorescent materials as emissive materials, and the second EL layer contains green and red phosphorescent materials as emissive materials. In addition, a first EL layer that emits red light and a second EL layer that contains The device has a second EL layer that emits green light and a third EL layer that emits blue light. Alternatively, a white light may be produced by using a configuration having light-emitting layers that emit light of complementary colors. In a stacked element in which two EL layers are stacked, light is emitted from the first EL layer. When the color of the light emitted from the first EL layer and the color of the light emitted from the second EL layer are in a complementary color relationship, Examples of the relationship include blue and yellow, or blue-green and red.

[0207] In the above-mentioned laminated element configuration, a charge generating layer is disposed between the laminated EL layers. This makes it possible to realize a long-life element in the high-luminance region while keeping the current density low. In addition, the voltage drop due to the resistance of the electrode material can be reduced, allowing for uniform light emission over a large area. This becomes possible.

[0208] This embodiment mode can be combined with any one of the first to fourth embodiments.

[0209] (Embodiment 6) In this embodiment mode, the appearance and cross section of a light-emitting display panel (also called a light-emitting panel) will be described with reference to FIG. FIG. 7(A) shows a thin film transistor and a light emitting device formed on a first substrate. FIG. 7 is a plan view of a panel in which an optical element is sealed between a second substrate and the panel by a sealant. (B) corresponds to a cross-sectional view taken along line HI in FIG. 7(A).

[0210] 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 to surround the gate 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.

[0211] 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. 7B, a thin film transistor 4510 included in a pixel portion 4502 and a signal A thin film transistor 4509 included in the line driver circuit 4503a is illustrated.

[0212] The thin film transistors 4509 and 4510 are the signal transistors including the oxide semiconductor layer described in Embodiment 1. Thin film transistors with high reliability can be used. Thin film transistors for driving circuits 4 As the transistor 509, the thin film transistor 450 shown in the embodiment mode 1, the thin film transistor for a pixel A thin film transistor 460 can be used as the transistor 4510. In this embodiment, the thin film transistors 4509 and 4510 are n-channel thin film transistors.

[0213] The oxide semiconductor layer of the thin film transistor 4509 for the driver circuit is formed over the insulating layer 4544. A conductive layer 4540 is provided in a position overlapping with the channel forming region. By providing the MOSFET in a position overlapping the channel formation region of the semiconductor layer, It is possible to reduce the amount of change in the threshold voltage of the thin film transistor 4509. The potential of the gate electrode layer 4540 may be the same as that of the gate electrode layer of the thin film transistor 4509 or may be different. The conductive layer 4 may be formed of a conductive material and may function as a second gate electrode layer. The potential of 540 may be GND, 0V, or may be in a floating state.

[0214] The thin film transistor 4509 includes an insulating layer 4541a functioning as a channel protective layer and an oxide An insulating layer 4541b is formed to cover the peripheral portion (including the side surface) of the laminate of the compound semiconductor layers.

[0215] In addition, the thin film transistor 4510 is electrically connected to the first electrode 4517 through a connection electrode layer 4548. In addition, an oxide semiconductor layer of the thin film transistor 4510 is electrically connected to the oxide An insulating layer 4542 is formed.

[0216] The oxide insulating layers 4541a, 4541b, and 4542 are the oxide insulating layer 4 shown in Embodiment 1. The oxide insulating layer 4541 may be formed using a material and a method similar to those of the oxide insulating layer 26a and the oxide insulating layer 426b. An insulating layer 4544 is formed to cover the layers 4541a, 4541b, and 4542. The insulating layer 428 may be formed using a material and a method similar to those of the insulating layer 428 described in the first embodiment.

[0217] A color filter layer 4545 is formed on the thin film transistor 4511 so as to overlap the light emitting region of the light emitting element 4511. It is formed on the star 4510.

[0218] In addition, the color filter layer 4545 functions as a planarizing insulating film to reduce surface irregularities. It is covered with an overcoat layer 4543 .

[0219] In addition, an insulating layer 4546 is formed on the overcoat layer 4543. The protective insulating layer 413 may be formed using a material and a method similar to those of the protective insulating layer 413 described in Embodiment 1.

[0220] Also, 4511 corresponds to a light emitting element, and the first electrode 4511 is a pixel electrode of the light emitting element 4511. 517 is electrically connected to a source electrode layer or a drain electrode layer of the thin film transistor 4510. The light emitting element 4511 is configured with a first electrode 4517, an electroluminescent layer 4512, and a The light-emitting element 4511 has a laminated structure of the first electrode 4512 and the second electrode 4513, but is not limited to the structure shown in the figure. The configuration of the light emitting element 4511 can be changed appropriately according to the direction of the light to be extracted from the do.

[0221] 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.

[0222] 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.

[0223] 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.

[0224] 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.

[0225] The connection terminal electrode 4515 is made of the same conductive film as the first electrode 4517 of the light-emitting element 4511. The terminal electrode 4516 is a source electrode layer and a drain electrode layer of the thin film transistor 4509. It is formed from the same conductive film as the electrode layer.

[0226] 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.

[0227] The second substrate is not transparent to light, and is located in the direction of light extraction from the light emitting element 4511. In this case, glass plates, plastic plates, polyester films or A light-transmitting material such as an acrylic film is used.

[0228] 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 EV A (ethylene vinyl acetate) can be used. For example, nitrogen can be used as a filler. That's good.

[0229] 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.

[0230] The signal line driver circuits 4503a and 4503b and the scanning line driver circuits 4504a and 4504b are A driving circuit formed of a single crystal semiconductor film or a polycrystalline semiconductor film on a separately prepared substrate is Also, only the signal line driver circuit, or a part of the signal line driver circuit, or the scanning line driver circuit may be mounted. Only the path or only a part of the path may be separately formed and mounted, and the configuration is not limited to that of FIG.

[0231] Through the above steps, a highly reliable light-emitting display device (display panel) can be manufactured as a semiconductor device. It is possible.

[0232] (Embodiment 7) In this embodiment, at least a part of the driver circuit and a thin film transistor to be disposed in the pixel portion are formed on the same substrate. An example of fabricating a transistor will be described below.

[0233] The thin film transistors arranged in the pixel portion are formed according to the first embodiment. The thin film transistor shown in the embodiment 1 is an n-channel TFT, so the n-channel A part of the driving circuit that can be configured with a panel-type TFT is the same as the thin-film transistor of the pixel part. It is formed on a substrate.

[0234] An example of a block diagram of an active matrix display device is shown in FIG. On the plate 5300, a pixel section 5301, a first scanning line driver circuit 5302, a second scanning line driver The pixel portion 5301 includes a signal line driver circuit 5303 and a signal line driver circuit 5304. A signal line driver circuit 5304 is extended from the first scanning line driver circuit 5305. 302 and a scanning line driver circuit 5303. In the intersection area of ​​each of the lines, pixels each having a display element are arranged in a matrix. The display device substrate 5300 is a flexible printed circuit board (FPC). t) and other connections to a timing control circuit 5305 (also called a controller or control IC). It is connected to the

[0235] In FIG. 9A, a first scanning line driver circuit 5302, a second scanning line driver circuit 5303, a signal The line driver circuit 5304 is formed on the same substrate 5300 as the pixel portion 5301. The number of externally provided components such as drive circuits is reduced, which contributes to cost reduction. In the case where a driving circuit is provided outside the substrate 5300, the wiring is extended to connect the driving circuit at the connection portion. The number of connections can be reduced, and the reliability or yield can be improved.

[0236] The timing control circuit 5305 is, for example, A first scanning line driving circuit start signal (GSP1), a scanning line driving circuit clock signal (GCK1). The timing control circuit 5305 also supplies the second scanning line driving circuit For example, the second scanning line driver circuit start signal (GSP2) (start The signal line supplies the clock signal (GCK2) for the scanning line driver circuit. A start signal (SSP) for the signal line driver circuit and a clock for the signal line driver circuit are input to the driver circuit 5304. Clock signal (SCK), data for video signal (DATA) (also simply called video signal), Each clock signal is a multiple of the clock signal (LAT) with different periods. It may be a clock signal or may be supplied together with an inverted clock signal (CKB). The first scanning line driver circuit 5302 and the second scanning line driver circuit 53 It is possible to omit either 03 or 04.

[0237] In FIG. 9B, circuits with low driving frequencies (for example, the first scanning line driving circuit 5302, the second The scanning line driver circuit 5303) is formed on the same substrate 5300 as the pixel portion 5301, and the signal line driver The circuit 5304 is formed on a substrate different from that of the pixel portion 5301. The thin film transistor has a smaller field effect mobility than a transistor using a single crystal semiconductor. A driver circuit formed on the substrate 5300 can be formed by using transistors. Therefore, it is possible to increase the size of the display device, reduce the cost, and improve the yield. .

[0238] The thin film transistor shown in the embodiment 1 is an n-channel TFT. ) and FIG. 10(B) shows the configuration and operation of a signal line driver circuit configured with an n-channel TFT. An example will be given below.

[0239] The signal line driver circuit includes a shift register 5601 and a switching circuit 5602 . The switching circuit 5602 includes switching circuits 5602_1 to 5602_N (N is a natural number). The switching circuits 5602_1 to 5602_N each have a A plurality of thin film transistors 5603_1 to 5603_k (k is a natural number) are provided. The thin film transistors 5603_1 to 5603_k are N-channel TFTs. An example will be explained.

[0240] The connection relationship of the signal line driver circuit will be described using the switching circuit 5602_1 as an example. The first terminals of the thin film transistors 5603_1 to 5603_k are respectively connected to the wiring 5604_1 The second terminals of the thin film transistors 5603_1 to 5603_k are connected to are connected to the signal lines S1 to Sk, respectively. The gate of k is connected to the wiring 5605_1.

[0241] The shift register 5601 sequentially outputs H level (H signal) to the wirings 5605_1 to 5605_N. , or high power supply potential level), and the switching circuits 5602_1 to 56 It has the function of selecting 02_N in sequence.

[0242] The switching circuit 5602_1 includes wirings 5604_1 to 5604_k and signal lines S1 to Sk. The function of controlling the conduction state (conduction between the first terminal and the second terminal) with the wiring 5604_ The switches have a function of controlling whether or not potentials of 1 to 5604_k are supplied to the signal lines S1 to Sk. In this way, the switching circuit 5602_1 has a function as a selector. The film transistors 5603_1 to 5603_k are connected to the wirings 5604_1 to 5604_k, respectively. and the signal lines S1 to Sk, that is, the wirings 5604_1 to 5604_k The thin film transistor 56 has a function of supplying the potential to the signal lines S1 to Sk. Each of 03_1 to 5603_k has a function as a switch.

[0243] In addition, the wirings 5604_1 to 5604_k each carry video signal data (DATA). The video signal data (DATA) is an analog signal corresponding to the image information or image signal. This is often a signal that

[0244] Next, the operation of the signal line driver circuit of FIG. 10(A) will be described with reference to the timing chart of FIG. 10(B). FIG. 10B shows signals Sout_1 to Sout_N and An example of Vdata_1 to Vdata_k is shown. These are examples of output signals of the shift register 5601, and signals Vdata_1 to Vdata _k are examples of signals input to the wirings 5604_1 to 5604_k, respectively. One operation period of the signal line driving circuit corresponds to one gate selection period in the display device. The selection period is divided into periods T1 to TN, for example. This is a period for writing video signal data (DATA) to the pixels belonging to the selected row. be.

[0245] In the drawings of the present embodiment, the signal waveforms of the components are not rounded for clarity. Therefore, the scale may not necessarily be limited to the actual scale. It should be noted that

[0246] During the period T1 to the period TN, the shift register 5601 outputs an H-level signal to the wiring 560 For example, in the period T1, the shift registers 5 601 outputs a high-level signal to the wiring 5605_1. Since 5603_1 to 5603_k are turned on, wiring 5604_1 to 5604_k and signal At this time, the wirings 5604_1 to 5604_k are in a conductive state. Data(S1)~Data(Sk) are input. Data(S1)~Data(Sk ) belong to a selected row via thin film transistors 5603_1 to 5603_k. In this way, during the periods T1 to TN, Then, the video signal data (DATA) is sent to the pixels in the selected row in order of k columns. It will be written.

[0247] As described above, video signal data (DATA) is written to the pixels in multiple columns. This makes it possible to reduce the number of video signal data (DATA) or the number of wirings. This reduces the number of connections to external circuits. By writing directly to the memory, the writing time can be increased, and the video signal can be written more quickly. This can prevent under-crowding.

[0248] The shift register 5601 and the switching circuit 5602 are the same as those in the first embodiment. It is possible to use a circuit composed of thin film transistors shown in 2, 5, and 6. In this case, the polarity of all the transistors in the shift register 5601 is set to N-channel type or The channel types can be configured with only one polarity.

[0249] Regarding one form of a shift register used as a part of a scanning line driver circuit and / or a signal line driver circuit, This will be described with reference to FIG. 11 and FIG.

[0250] The configuration of the scanning line driver circuit will be described. The scanning line driver circuit has a shift register. In some cases, a level shifter, a buffer, etc. may be included. In the line driver circuit, a clock signal (CLK) and a start pulse signal are input to the shift register. A selection signal is generated by inputting (SP). The generated selection signal is The signal is buffered and amplified in the amplifier and fed to the corresponding scanning line. The gate electrodes of the pixel transistors in one line are connected. Since all the drivers must be turned on at the same time, the buffer must be able to pass a large current. Things like that are used.

[0251] The shift registers of the scanning line driver circuit and the signal line driver circuit are shown in FIG. 11 and FIG. 12. The shift register includes a first pulse output circuit 10_1 to an Nth pulse output circuit 10_2. The circuit 10 has a path 10_N (N is a natural number equal to or greater than 3) (see FIG. 11(A)). The first pulse output circuit 10_1 to the N-th pulse output circuit 10_N of the shift register shown in FIG. A first clock signal CK1 is output from a first wiring 11, a second clock signal CK2 is output from a second wiring 12, a third clock signal CK2 from the third wiring 13; a fourth clock signal CK3 from the fourth wiring 14; The clock signal CK4 is supplied to the first pulse output circuit 10_1. A start pulse SP1 (first start pulse) is input from line 15. In the subsequent n-th pulse output circuit 10_n (n is a natural number between 2 and N), A signal from the pulse output circuit 10_n-1 (called the previous stage signal OUT(n-1)) is input. In addition, in the first pulse output circuit 10_1, the third pulse output circuit 10_3, which is two stages behind, Similarly, in the n-th pulse output circuit 10_n in the second stage or later, a signal from The signal from the (n+2)th pulse output circuit 10_(n+2) in the subsequent stage (subsequent stage signal OUT( Therefore, the pulse output circuit of each stage outputs the following stage and / or The first output signal (OUT(1)(SR)~ OUT(N)(SR)), a second output signal (OUT(1) to OU However, as shown in FIG. 11(A), the final stage of the shift register Since the next stage signal OUT(n+2) is not input to the first two stages, The second start pulse SP2 and the third start pulse SP3 are input. Good.

[0252] The clock signal (CK) goes between H and L levels (L signal, low power supply potential) at regular intervals. Here, the first clock signal (CK1) to the second clock signal (CK2) are The fourth clock signal (CK4) is delayed by 1 / 4 cycle in sequence. The first clock signal (CK1) to the fourth clock signal (CK4) are used to generate a pulse output circuit. The clock signal is GCK depending on the input drive circuit. It is sometimes called SCK, but here we will use CK for explanation.

[0253] Each of the first pulse output circuit 10_1 to the N-th pulse output circuit 10_N has a first input terminal a first input terminal 21, a second input terminal 22, a third input terminal 23, a fourth input terminal 24, a fifth input terminal The input terminal 25, the first output terminal 26, and the second output terminal 27 (see FIG. 11(B)). The first input terminal 21, the second input terminal 22, and the third input terminal 23 are connected to the first wiring 11 to 14. For example, in FIG. In the first pulse output circuit 10_1, the first input terminal 21 is electrically connected to the first wiring 11. , the second input terminal 22 is electrically connected to the second wiring 12, and the third input terminal 23 is electrically connected to the third wiring 13. In addition, the second pulse output circuit 10_2 In the example shown in FIG. 1, the first input terminal 21 is electrically connected to the second wiring 12, and the second input terminal 22 is The third input terminal 23 is electrically connected to the fourth wiring 14. It has been done.

[0254] In the first pulse output circuit 10_1, a first clock signal CK is input to a first input terminal 21. 1 is input to the first input terminal 21, the second clock signal CK2 is input to the second input terminal 22, and the third input The third clock signal CK3 is input to the terminal 23, and the first start A pulse SP1 is input, a subsequent signal OUT(3) is input to the fifth input terminal 25, and a first The first output signal OUT(1)(SR) is output from the output terminal 26, and the second output signal OUT(2)(SR) is output from the output terminal 2 7 outputs the second output signal OUT(1).

[0255] The first pulse output circuit 10_1 to the N-th pulse output circuit 10_N are each a three-terminal thin-film transistor. In addition to TFTs (also called Thin Film Transistors), The four-terminal thin film transistor described in the above embodiment can be used. 1 shows a symbol of the four-terminal thin film transistor 28 described in the above embodiment. The symbol of the thin film transistor 28 shown in FIG. 11(C) corresponds to that of the first, second, fifth and sixth embodiments. This term refers to a four-terminal thin-film transistor described in any one of the above, and will be used hereinafter in drawings, etc. In this specification, a thin film transistor has two gate electrodes via a semiconductor layer. In the case where the gate electrode is disposed below the semiconductor layer, the gate electrode is disposed above the semiconductor layer. The gate electrode of the thin film transistor 28 is also called the upper gate electrode. a first control signal G1 input to the gate electrode above the first gate electrode and a second control signal G2 input to the gate electrode above the first gate electrode. This is an element that can perform electrical control between the In terminal and the Out terminal.

[0256] When an oxide semiconductor is used for a semiconductor layer including a channel formation region of a thin film transistor, The threshold voltage may shift to the negative or positive side depending on the process. Therefore, in a thin film transistor in which an oxide semiconductor is used for a semiconductor layer including a channel formation region, A structure capable of controlling the threshold voltage is preferable. The threshold voltage of the thin film transistor 28 is determined by gate electrodes above and below the channel forming region of the thin film transistor 28. A gate electrode is provided through a gate insulating film, and the potential of the upper and / or lower gate electrodes is controlled. By doing so, it is possible to control the value to a desired value.

[0257] Next, an example of a specific circuit configuration of the pulse output circuit will be described with reference to FIG.

[0258] The first pulse output circuit 10_1 includes a first transistor 31 to a thirteenth transistor 4. 3 (see FIG. 11(D)). Also, a power supply 3 to which a first high power supply potential VDD is supplied A power supply line 51 is connected to a power supply line 52 to which a second high power supply potential VCC is supplied, and a power supply line 53 is connected to which a low power supply potential VSS is supplied. A signal is supplied to the first transistor 31 to the thirteenth transistor 43 from a power supply line 53. The power supply potential is supplied to the power supply lines. Here, the magnitude relationship of the power supply potentials of the power supply lines in FIG. 11(D) is as follows: The power supply potential VDD is set to a potential equal to or higher than the second power supply potential VCC, and the second power supply potential VCC is set to a potential equal to or higher than the third power supply potential VCC. The potential is set to be higher than the power supply potential VSS. The lock signal (CK4) is a signal that alternates between H and L levels at regular intervals. When the potential of the power supply line 51 is high, it is VDD, and when the potential is low, it is VSS. By making the potential of the power supply line 52 higher than the potential VCC, the transistor The potential applied to the gate electrode of the transistor can be kept low, and the threshold of the transistor can be As shown in FIG. 11(D), the shift in the value can be reduced and deterioration can be suppressed. Among the first transistor 31 to the thirteenth transistor 43, the first transistor 3 1. The sixth transistor 36 to the ninth transistor 39 are the four transistors shown in FIG. It is preferable to use the thin film transistor 28 of the terminal. The operation of the transistors 36 to 9th transistors 39 is controlled by the voltages acting as the source and drain. The potential of the node to which one of the electrodes is connected can be switched by the control signal of the gate electrode. This is a transistor that is required to have a fast response to the control signal input to the gate electrode ( The steep rise of the on-current reduces malfunctions in the pulse output circuit. Therefore, the four-terminal thin film transistor 28 shown in FIG. By using this pulse, the threshold voltage can be controlled, and malfunctions can be further reduced. In FIG. 11D, the first control signal G1 and the second control signal G2 are Although the signal G2 is the same control signal, a configuration in which different control signals are input may be used.

[0259] In FIG. 11D, the first transistor 31 has a first terminal electrically connected to a power supply line 51. a second terminal electrically connected to a first terminal of a ninth transistor 39; (the lower gate electrode and the upper gate electrode) are electrically connected to the fourth input terminal 24. The second transistor 32 has a first terminal electrically connected to the power supply line 53 and a second terminal a gate electrode electrically connected to the first terminal of the ninth transistor 39 and a gate electrode electrically connected to the first terminal of the fourth transistor The third transistor 33 is electrically connected to the gate electrode of the first terminal The first terminal is electrically connected to the first input terminal 21, and the second terminal is electrically connected to the first output terminal 26. The fourth transistor 34 has a first terminal electrically connected to the power supply line 53, The second terminal is electrically connected to the first output terminal 26. The fifth transistor 35 is The first terminal is electrically connected to the power supply line 53, and the second terminal is connected to the gate of the second transistor 32. The electrode of the fourth transistor 34 is electrically connected to the gate electrode of the fourth transistor 34. The sixth transistor 36 has a first terminal electrically connected to the power supply line 52, and the second terminal is electrically connected to the gate electrode of the second transistor 32 and the gate electrode of the fourth transistor 33. The gate electrode of the transistor 34 is electrically connected to the gate electrode of the transistor 34. The seventh transistor (the gate electrode of the seventh transistor) is electrically connected to the fifth input terminal 25. The eighth transistor 37 has a first terminal electrically connected to the power supply line 52 and a second terminal electrically connected to the eighth transistor 38. and a gate electrode (a lower gate electrode and an upper gate electrode) electrically connected to the second terminal of the is electrically connected to the third input terminal 23. The eighth transistor 38 is is electrically connected to the gate electrode of the second transistor 32 and the gate electrode of the fourth transistor 34. and the gate electrodes (the lower gate electrode and the upper gate electrode) are connected to the second input terminal The ninth transistor 39 has a first terminal electrically connected to the first transistor 22. The second terminal is electrically connected to the second terminal of the second transistor 31 and the second terminal of the second transistor 32. The gate electrode of the third transistor 33 and the gate electrode of the tenth transistor 40 are connected to The gate electrodes (the lower gate electrode and the upper gate electrode) are electrically connected to the power supply line 52. The tenth transistor 40 has a first terminal electrically connected to the first input terminal 2. 1, the second terminal is electrically connected to the second output terminal 27, and the gate electrode is electrically connected to the second terminal of the ninth transistor 39. 41 has a first terminal electrically connected to the power supply line 53 and a second terminal electrically connected to the second output terminal 27. The gate electrodes of the second transistor 32 and the fourth transistor The twelfth transistor 42 is electrically connected to the gate electrode of the first terminal of the transistor 34. The first terminal is electrically connected to the power supply line 53, and the second terminal is electrically connected to the second output terminal 27. The gate electrode of the seventh transistor 37 (the lower gate electrode and the upper gate electrode) The thirteenth transistor 43 has a first terminal electrically connected to the power supply line 5 3, the second terminal is electrically connected to the first output terminal 26, and the gate electrode The seventh transistor 37 has a gate electrode (lower gate electrode and upper gate electrode) are electrically connected.

[0260] In FIG. 11D, the gate electrode of the third transistor 33, the gate electrode of the tenth transistor The connection point of the gate electrode of the ninth transistor 40 and the second terminal of the ninth transistor 39 is defined as node A. In addition, the gate electrode of the second transistor 32, the gate electrode of the fourth transistor 34, The second terminal of the fifth transistor 35, the second terminal of the sixth transistor 36, the second terminal of the eighth transistor The connection point of the first terminal of the transistor 38 and the gate electrode of the eleventh transistor 41 is a node Let's call it B.

[0261] FIG. 12A shows the pulse output circuit described in FIG. 11D as a first pulse output circuit 10_ 1, the first input terminal 21 to the fifth input terminal 25 and the first output terminal 26 and a signal input to or output from a second output terminal 27.

[0262] Specifically, a first clock signal CK1 is input to the first input terminal 21, and A second clock signal CK2 is input to the third input terminal 22, and a third clock signal CK3 is input to the third input terminal 23. A start pulse is input to the fourth input terminal 24, and a clock signal CK3 is input to the fifth input terminal The next stage signal OUT(3) is input to the first output terminal 25, and the first output signal OUT (1)(SR) is output, and the second output signal OUT(1) is output from the second output terminal 27. will be done.

[0263] A thin film transistor is defined as a transistor having at least three elements including a gate, a drain, and a source. An element having terminals, and a channel region between a drain region and a source region, A current can be passed through the drain region, the channel region, and the source region. The source and drain are different depending on the structure and operating conditions of the thin film transistor. It is difficult to determine whether the source or drain is the same. In some cases, the region that functions as a drain is not called a source or drain. As an example, they may be referred to as a first terminal and a second terminal, respectively.

[0264] In FIG. 11(D) and FIG. 12(A), the node A is made floating, so that the boot A capacitor may be provided separately to perform a strap operation. To achieve this, a capacitor having one electrode electrically connected to the node B may be provided separately.

[0265] Here, the timing of the shift register having a plurality of pulse output circuits shown in FIG. A shift register is a scanning line driver circuit. In this case, the period 61 in FIG. 12B corresponds to a vertical blanking period, and the period 62 corresponds to a gate selection period. do.

[0266] As shown in FIG. 12A, the ninth transistor has a gate to which the second power supply potential VCC is applied. By providing the transistor 39, the following can be achieved before and after the bootstrap operation: There are such advantages.

[0267] In the absence of the ninth transistor 39 having the gate electrode to which the second potential VCC is applied, the boot When the potential of the node A rises due to the strap operation, the second terminal of the first transistor 31 The potential of the source, which is the first power supply potential VDD, increases and becomes higher than the first power supply potential VDD. The source of the first transistor 31 is switched to the first terminal side, that is, the power supply line 51 side. In the first transistor 31, the gate and source, and the gate and drain are In addition, a large bias voltage is applied, which causes a large stress and leads to deterioration of the transistor. Therefore, the ninth transistor, whose gate electrode is applied with the second power supply potential VCC, By providing the transistor 39, the potential of the node A is set by the bootstrap operation. However, the potential of the second terminal of the first transistor 31 does not increase. That is, by providing the ninth transistor 39, The negative bias voltage applied between the gate and source of the transistor 31 can be reduced. Therefore, by using the circuit configuration of this embodiment, the gate of the first transistor 31 The negative bias voltage applied between the gate and source can also be reduced, reducing the first-order This makes it possible to suppress the deterioration of the transistor 31.

[0268] The ninth transistor 39 is provided at a position corresponding to the second gate of the first transistor 31. A terminal is connected between the terminal and the gate of the third transistor 33 via a first terminal and a second terminal. In addition, in the present embodiment, a system having a plurality of pulse output circuits may be provided. In the case of a soft register, the signal line driver circuit has more stages than the scan line driver circuit. The resistor 39 may be omitted, which has the advantage of reducing the number of transistors.

[0269] Note that the semiconductor layers of the first to thirteenth transistors 31 to 43 are made of oxide semiconductor. By using a conductor, the off-current of the thin film transistor is reduced, and the on-current and Because it is possible to increase the field effect mobility and reduce the degree of degradation. In addition, a transistor including an oxide semiconductor can be Compared to transistors using amorphous silicon, a high potential is applied to the gate electrode. Therefore, the degree of deterioration of the transistor due to the second power supply potential VCC is small. The same operation can be obtained by supplying the first power supply potential VDD to the power supply line. Since the number of power lines to be routed can be reduced, the circuit can be made more compact.

[0270] The gate electrodes (lower gate electrode and upper gate electrode) of the seventh transistor 37 a clock signal provided by the third input terminal 23 to the gate of the eighth transistor 38; The input electrodes (lower gate electrode and upper gate electrode) are supplied with a second input terminal 22. The clock signal is applied to the gate electrode of the seventh transistor 37 (the lower gate electrode and the upper gate electrode). A clock signal is supplied to the gate electrode of the eighth transistor by the second input terminal 22. The third input terminal 23 is connected to the gate electrodes (lower gate electrode and upper gate electrode) of the gate electrode of the transistor 38. The same effect can be obtained by swapping the wiring so that the clock signal is supplied by In the shift register shown in FIG. The seventh transistor 37 is turned off and the eighth transistor 38 is turned on. The transistor 38 is on, then the seventh transistor 37 is off, and the eighth transistor By turning off the input terminal 38, the second input terminal 22 and the third input terminal 23 are The voltage drop at node B is generated by the gate of the seventh transistor 37. due to a drop in the potential of the gate electrode of the eighth transistor 38 and a drop in the potential of the gate electrode of the eighth transistor 39. On the other hand, if the shift register shown in FIG. 12(A) is changed to that shown in FIG. 12(B), Then, the seventh transistor 37 and the eighth transistor 38 are both turned on. The transistor 37 is on, the eighth transistor 38 is off, and then the seventh transistor The second input transistor 37 is turned off and the eighth transistor 38 is turned off. A decrease in the potential of the node B caused by a decrease in the potential of the input terminal 22 and the third input terminal 23 can be reduced to one time due to the drop in the potential of the gate electrode of the eighth transistor 38. Therefore, the gate electrode of the seventh transistor 37 (the lower gate electrode and the upper gate electrode) A clock signal is supplied to the third input terminal 23 from the third input terminal 24, and the eighth transistor 38 The gate electrodes (lower gate electrode and upper gate electrode) are connected to a clock signal from the second input terminal 22. It is preferable to use a wiring relationship in which a clock signal is supplied to the node B. This is because the number of times is reduced, and noise can be reduced.

[0271] In this way, the potentials of the first output terminal 26 and the second output terminal 27 are held at the L level. By configuring the node B to periodically receive a high-level signal during this period, It is possible to suppress malfunction of the output circuit.

[0272] (Embodiment 8) In this embodiment, a manufacturing process of a thin film transistor is partially different from that in Embodiment 1. FIG. 8 is the same as FIG. 1 except for some steps, so the same parts are designated by the same reference numerals. Reference numbers will be used and detailed explanations of the same parts will be omitted.

[0273] First, according to the first embodiment, two types of gate electrode layers and a gate insulating layer 402 are formed on a substrate. a source electrode layer 455a which is partially overlapped with one of the gate electrode layers via a gate insulating layer; Then, the gate insulating layer 402, the source electrode layer 403, and the drain electrode layer 455b are formed. An oxide semiconductor film is formed over the drain electrode layer 55a and the drain electrode layer 455b.

[0274] Next, the oxide semiconductor film is dehydrated or dehydrogenated. The temperature of the heat treatment in step 1 is 400° C. or higher and lower than the distortion point of the substrate, preferably 425° C. or higher. If the temperature is 425℃ or higher, the heat treatment time can be 1 hour or less. The heat treatment time is longer than one hour. The substrate is placed in an electric furnace, and the oxide semiconductor film is subjected to heat treatment in a nitrogen atmosphere. After that, the oxide semiconductor film is not exposed to the air, and impurities such as water and hydrogen are prevented from re-mixing into the oxide semiconductor film. After that, high-purity oxygen gas, high-purity N2O gas, or Cooling is performed by introducing ultra-dry air (dew point below -40°C, preferably below -60°C). It is preferable that the oxygen gas or N2O gas does not contain water, hydrogen, etc. The purity of oxygen gas or N2O gas introduced into the treatment device must be 6N (99.9999%) or higher. Preferably, the impurities in the oxygen gas or N2O gas are 7N (99.99999%) or more. It is preferable to keep the concentration of impurities at 1 ppm or less, and preferably at 0.1 ppm or less.

[0275] After the first heat treatment for dehydration or dehydrogenation, the temperature is preferably 200° C. or higher and 400° C. or lower. Or heat treatment at a temperature between 200°C and 300°C in an oxygen gas or N2O gas atmosphere. The theory may also be carried out.

[0276] By going through the above steps, the entire oxide semiconductor film is made into an oxygen-excess state, and thus a high resistance Note that in this embodiment, the oxide semiconductor film is dehydrated or However, the present invention is not limited to the above, and may be applied to an oxide semiconductor It is sufficient if it is a process after the film formation.

[0277] Next, the oxide semiconductor film and the gate insulating layer 402 are selectively formed by a photolithography process. A contact hole reaching the gate electrode layer 421b is formed by etching the oxide semiconductor. By forming a resist on the conductive film, the boundary between the gate insulating layer 402 and the oxide semiconductor film is The state after removing the resist mask is shown in Figure 8(A). vinegar.

[0278] Next, after removing the resist mask, a resist mask is formed again, and the oxide semiconductor film is The oxide semiconductor layer is selectively etched to be an island-shaped oxide semiconductor layer. Then, the resist mask is removed. Then, oxide semiconductor layers 404 and 405 are obtained over the gate insulating layer 402 (see FIG. 8B). ).

[0279] Next, an oxide semiconductor film was formed on the gate insulating layer 402 and the oxide semiconductor layers 404 and 405 by a sputtering method. After forming the oxide insulating film, a resist mask is formed by a photolithography process, and a selective Then, the oxide insulating layers 426a and 426b are formed by selectively etching the resist mask. At this stage, the oxide semiconductor layer is in contact with the oxide insulating layer. In this region, a region overlapping with the gate electrode layer, the gate insulating layer, and the oxide insulating layer 426a is The oxide insulating layer 426 covers the periphery and side surfaces of the oxide semiconductor layer. In addition, the gate insulating layer 4 is also formed in an area overlapping with the gate insulating layer 4b by this photolithography process. Formation of a contact hole reaching 21b and a contact reaching the drain electrode layer 455b Holes are also formed (see FIG. 8(C)).

[0280] The oxide insulating film is resistant to moisture, hydrogen ions, and OH - It does not contain impurities such as An inorganic insulating film is used to block the penetration of oxygen from the atmosphere. Representative examples include silicon oxide film and silicon nitride oxide film. An aluminum oxide film, an aluminum oxynitride film, or the like is used.

[0281] Next, the gate insulating layer 402, the oxide insulating layers 426a and 426b, and the oxide semiconductor layer are A laminate of an oxide conductive film and a metal conductive film is formed on the substrate. The metal conductive film can be continuously formed without being exposed to the air.

[0282] The oxide conductive film preferably contains zinc oxide as a component, and more preferably contains indium oxide. As such an oxide conductive film, zinc oxide, zinc oxide Examples of the zinc oxide include aluminum, zinc aluminum oxynitride, and zinc gallium oxide. In the embodiment, a zinc oxide film is used.

[0283] The metal conductive film is made of an element selected from Ti, Mo, W, Al, Cr, Cu, and Ta. The alloys used are those containing the above elements or those combining the above elements. In addition, the layer is not limited to a single layer containing the above-mentioned elements, and a laminate of two or more layers can be used. In this embodiment, a three-layer laminate of a molybdenum film, an aluminum film, and a molybdenum film is used. A membrane is used.

[0284] Next, a resist mask is formed, and the metal conductive film is selectively etched to form the source electrode layer 4. 45a, the drain electrode layer 445b, the connection electrode layer 449, and the connection electrode layer 442 were formed. After that, the resist mask is removed. The resist stripping solution is an alkaline solution. When using the resist stripping solution, the source electrode layer 44 5a, the drain electrode layer 445b, the connection electrode layer 449, and the connection electrode layer 442 are used as a mask. The zinc oxide film is selectively etched. An oxide conductive layer 446b is formed under and in contact with the drain electrode layer 445b. An oxide conductive layer 446a is provided between the source electrode layer 445a and the oxide semiconductor layer. By using this method, the contact resistance can be reduced, and a thin film transistor capable of high-speed operation can be realized. An oxide semiconductor layer provided between the source electrode layer 445a and the oxide semiconductor layer can be realized. The oxide semiconductor conductive layer 446a functions as a source region, and the drain electrode layer 445b and the oxide semiconductor The oxide conductive layer 446b provided between the periphery and the gate electrode functions as a drain region. It is effective in improving the frequency characteristics of the drive circuit. When the material is in direct contact with the semiconductor layer, the contact resistance becomes high. Since O is difficult to oxidize, it has a weak effect of extracting oxygen from the oxide semiconductor layer. This is because the contact interface between the oxide semiconductor layer and the oxide semiconductor layer does not become n-type. The oxide conductive layer 446a is interposed between the oxide semiconductor layer and the drain electrode layer. By providing the oxide conductive layer 446b between the conductive layer 446 and the peripheral circuit (driver The frequency characteristics of the amplifier (drive circuit) can be improved.

[0285] In the same process, an oxide conductive layer 448 is formed below and in contact with the connection electrode layer 449. An oxide conductive layer 447 is formed under and in contact with the electrode layer 442 (see FIG. 8(D)). By forming the oxide conductive layer 448 between the electrode layer 449 and the gate electrode layer 421b, This is preferable because it acts as a buffer, and further because it does not form an insulating oxide with metals.

[0286] Since the oxide semiconductor layer and the oxide conductive layer have different etching rates, The overlying oxide conductive layer can be removed in a time controlled manner.

[0287] In addition, after selectively etching the metal conductive film, the resist mask is removed by oxygen ashing. After removing the zinc oxide film, the source electrode layer 445a and the drain electrode layer 445b are The zinc oxide film is selectively etched using the connection electrode layer 449 and the connection electrode layer 442 as a mask. You may also use the

[0288] In addition, when the first heat treatment is performed after selectively etching the metal conductive film, the oxide conductive film is The layers 446a, 446b, 447, and 448 contain a crystallization inhibitor such as silicon oxide. Unless the oxide conductive layers 446a, 446b, 447, and 448 are crystallized, The oxide semiconductor layer is not crystallized by the heat treatment and remains amorphous. The crystals of the layer grow columnarly on the substrate, forming the source and drain electrodes. In order to achieve this, when etching the metal film on the oxide conductive layer, the lower oxide conductive layer is The formation of undercuts can be prevented.

[0289] Next, in order to reduce the variation in the electrical characteristics of the thin-film transistors, or a second heat treatment (preferably at 150° C. or higher and lower than 350° C.) in a nitrogen gas atmosphere. For example, a heat treatment may be performed at 250° C. for 1 hour in a nitrogen atmosphere. By the heat treatment, oxygen is diffused into the oxide semiconductor layer. The diffusion of elements makes it possible to make the channel formation region highly resistive (i-type). In this way, a normally-off thin film transistor can be obtained. As a result, the oxide conductive layers 446a, 446b, 447, and 448 are crystallized, and the conductivity is improved. It can also be done.

[0290] Next, the oxide insulating layers 426a and 426b, the source electrode layer 445a, and the drain electrode layer 44 An insulating layer 428 is formed on 5b (see FIG. 8(E)).

[0291] Through the above steps, a thin film transistor 440 and a thin film transistor 460 are formed on the same substrate. It can be made.

[0292] The thin film transistor 440 disposed in the driving circuit is formed on the substrate 400 having an insulating surface. The gate electrode layer 421a, the gate insulating layer 402, at least the channel forming region 443, and the high resistance The oxide semiconductor layer includes a source region 444a and a high-resistance drain region 444b. The semiconductor memory device includes a source electrode layer 446a and a drain electrode layer 445a and a drain electrode layer 445b. In addition, an oxide insulating layer 426a is provided in contact with the channel formation region 443. An insulating layer 428 is provided over the source electrode layer 445a and the drain electrode layer 445b.

[0293] Between the high-resistance source region 444a and the source electrode layer 445a, a region that functions as a source region is provided. The oxide conductive layer 446a is provided, and the high-resistance drain region 444b and the drain electrode layer 445 are provided. The oxide conductive layer 446b functioning as a drain region is provided between the first and second conductive layers 446a and 446b. We are working to reduce this.

[0294] In addition, the first region 444c and the second region 444 of the oxide semiconductor layer overlap with the oxide insulating layer 426b. 4d is in the same oxygen-excess state as the channel formation region 443, and is effective in reducing leakage current and reducing parasitic capacitance. The insulating layer 428 also serves to reduce parasitic capacitance. The third region 444e is provided between the channel formation region 443 and the high resistance source region 444a. The fourth region 444f of the oxide semiconductor layer in contact with the insulating layer 428 is a channel formation region. The oxide layer 428 is disposed between the high-resistance drain region 443 and the high-resistance drain region 444b. The third region 444e and the fourth region 444f of the semiconductor layer can reduce the off current. do.

[0295] This embodiment mode can be freely combined with any one of the embodiment modes 1 to 7.

[0296] (Embodiment 9) The light emitting device disclosed in this specification can be applied to various electronic devices (including gaming machines). The electronic device can be, for example, a television device (a television or a television receiver). (also called "transmitting devices"), computer monitors, digital cameras, digital video cameras , digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable games Examples include gaming machines, mobile information terminals, audio playback devices, and large game machines such as pachinko machines. .

[0297] FIG. 13A shows an example of a mobile phone 1100. The mobile phone 1100 has a housing. In addition to the display unit 1102 incorporated in the 1101, the operation buttons 1103 and the external connection port 11 04, a speaker 1105, a microphone 1106, etc.

[0298] In the mobile phone 1100 shown in FIG. 13A, information is displayed by touching a display unit 1102 with a finger or the like. In addition, operations such as making a phone call or sending an e-mail can be performed without using the display. This can be done by touching the display unit 1102 with a finger or the like.

[0299] The screen of the display unit 1102 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.

[0300] For example, when making a call or composing an e-mail, the display unit 1102 is used to input 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 1102. I wish.

[0301] In addition, the mobile phone 1100 may include a sensor for detecting tilt, such as a gyro or an acceleration sensor. By providing a detection device having the above configuration, the orientation of the mobile phone 1100 (portrait or landscape) can be determined and the display The screen display of the display unit 1102 can be automatically switched.

[0302] The screen mode can be changed by touching the display unit 1102 or by operating the housing 1101. This is done by operating the button 1103. Also, depending on the type of image displayed on the display unit 1102, 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.

[0303] In the input mode, the optical sensor of the display unit 1102 detects a signal and displays If there is no input by touch operation of the unit 1102 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.

[0304] The display unit 1102 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.

[0305] The display portion 1102 includes a plurality of thin film transistors 460 described in Embodiment 1. Since the film transistor 460 has a light-transmitting property, when a photosensor is provided in the display portion 1102, In this case, the thin film transistor 460 does not block the incident light. When using a backlight that emits external light or a sensing light source that emits near-infrared light This is preferable because the thin film transistor 460 does not block light.

[0306] FIG. 13(B) is also an example of a mobile phone. The portable information terminal shown in FIG. 13(B) is It can have multiple functions. For example, in addition to the telephone function, it can have a built-in computer and perform various functions. It can also be equipped with various data processing functions.

[0307] The portable information terminal shown in FIG. 13B has two housings, a housing 1800 and a housing 1801. The housing 1800 includes a display panel 1802, a speaker 1803, a microphone, and the like. 1804, operation keys 1805, pointing device 1806, camera lens The housing 1801 includes a keyboard 1810. , an external memory slot 1811, etc. Also, the antenna is installed inside the housing 1801. It is built in.

[0308] The display panel 1802 is equipped with a touch panel, and in FIG. A plurality of operation keys 1805 are indicated by dotted lines.

[0309] In addition to the above configuration, a non-contact IC chip, a small recording device, etc. may be built in. .

[0310] The light emitting device can be used in a display panel 1802, and the display direction can be changed depending on the usage mode. Also, a camera lens 1807 is provided on the same surface as the display panel 1802. The speaker 1803 and microphone 1804 are Not only voice calls, but also video calls, recording, playback, etc. are possible. The housing 1801 slides and is folded from the unfolded state shown in FIG. 13(B) to the folded state. The device can be made compact and portable.

[0311] The external connection terminal 1808 can be connected to various cables such as AC adapters and USB cables. It is possible to charge the battery and to communicate data with a personal computer, etc. By inserting a recording medium into the memory slot 1811, it is possible to store and transfer a larger amount of data. do.

[0312] In addition to the above functions, it also has infrared communication function, TV reception function, etc. Good too.

[0313] FIG. 14A 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.

[0314] 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.

[0315] 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).

[0316] In order to provide a plurality of thin film transistors 460 described in Embodiment 1 in the display portion 9603, The aperture ratio can be increased, particularly when the light emitting device is of a bottom emission type.

[0317] FIG. 14B 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.

[0318] In order to provide a plurality of thin film transistors 460 described in Embodiment 1 in the display portion 9703, The aperture ratio can be increased, particularly when the light emitting device is of a bottom emission type.

[0319] 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 .

[0320] 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.

[0321] FIG. 15 shows a portable gaming machine, which is composed of two cabinets, a cabinet 9881 and a cabinet 9891. The housing 9881 includes a display unit 988 and a connector 9893 for connecting the display unit 988 to the housing 9881 in an openable and closable manner. 2 is incorporated in the housing 9891, and a display unit 9883 is incorporated in the housing 9891.

[0322] In order to provide a plurality of thin film transistors 460 described in Embodiment 1 in the display portion 9883, The aperture ratio can be increased, particularly when the light emitting device is of a bottom emission type.

[0323] In addition, the portable gaming machine shown in FIG. 15 also includes a speaker unit 9884, a recording medium insertion unit 9 886, LED lamp 9890, input means (operation key 9885, connection terminal 9887, sensor Sa9888 (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature degree, chemicals, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient 9889) microphones, etc. Of course, the configuration of the portable gaming machine is not limited to the above, and at least It is sufficient that the device is equipped with the thin film transistor disclosed in the specification, and other auxiliary equipment is provided as appropriate. The portable game machine shown in FIG. The function of reading out the program or data stored in the device and displaying it on the display unit, as well as wireless communication with other portable gaming machines, The portable game machine shown in FIG. 15 has a function for communicating with the player and sharing information. The functions are not limited to these, and may have a variety of functions.

[0324] FIG. 16 shows a light emitting device formed by applying the above embodiment as an indoor lighting device 3001. The light emitting device shown in the second embodiment can be enlarged. The light-emitting device described in the above embodiment 2 can be used as a lighting device. It can also be used as a tabletop lighting fixture 3000. In addition to lighting fixtures and tabletop lighting fixtures, this also includes wall-mounted lighting fixtures, in-car lighting, and emergency exit lights. can be.

[0325] As described above, the light emitting devices shown in the second and third embodiments can be used in the above-described manner. The thin film transistor 450 can be disposed in the display panel of various electronic devices. and the thin film transistor 460 is used as a switching element of the display panel. As a result, the light emitting device has a highly reliable display having a high aperture ratio, particularly when the light emitting device is a bottom emission type. It is possible to provide high-quality electronic equipment. [Explanation of symbols]

[0326] 400 Substrates 402 Gate insulating layer 403 Oxide semiconductor layer 404 Oxide semiconductor layer 411 First Terminal 412 Connection electrode layer 413 Protective Insulation Layer 414 Second Terminal 415 Conductive Layer 416 Electrode layer 417 Conductive Layer 418 Conductive Layer 421a Gate electrode layer 421b Gate electrode layer 421c Gate wiring layer 422 Source wiring layer 423 Channel formation region 424a High resistance source region 424b High-resistance drain region 424c 1st area 424d 2nd area 424e Third area 424f 4th area 425a Source electrode layer 425b Drain electrode layer 426a Oxide insulating layer 426b Oxide insulating layer 428 Insulating Layer 429 Connection electrode layer 430 Capacitive wiring layer 431 Capacitive electrode layer 440 Thin Film Transistor 441 Oxide Semiconductor Layer 442 Connection electrode layer 443 Channel Formation Region 444a High resistance source region 444b High-resistance drain region 444c 1st area 444d 2nd area 444e Third area 444f 4th area 445a Source electrode layer 445b Drain electrode layer 446a Oxide conductive layer 446b Oxide conductive layer 447 Oxide Conductive Layer 448 Oxide Conductive Layer 449 Connection electrode layer 450 Thin Film Transistor 451a Gate electrode layer 451b Gate electrode layer 452 Connection electrode layer 453 Oxide Semiconductor Layer 454 Oxide semiconductor layer 455a Source electrode layer 455b Drain electrode layer 456 Color filter layer 457 1st electrode 458 Overcoat layer 459 Bulkhead 460 Thin Film Transistor

Claims

1. A display device having a first transistor and a second transistor, a first insulating layer provided above the substrate; a first conductive layer having a region located above the first insulating layer and functioning as one of a source electrode and a drain electrode of the first transistor; a first semiconductor layer having a region in contact with an upper surface of the first conductive layer and having a channel formation region of the first transistor; a second semiconductor layer having a region located above the first insulating layer and having a channel formation region of the second transistor; a second insulating layer having a region in contact with an upper surface of the first semiconductor layer and including silicon oxide; a second conductive layer having a region in contact with a top surface of the second insulating layer and functioning as one of a source electrode and a drain electrode of the second transistor; a third conductive layer having a region in contact with an upper surface of the second insulating layer and a region in contact with an upper surface of the first conductive layer at an opening in the second insulating layer; a third insulating layer having a region in contact with an upper surface of the second conductive layer and a region in contact with an upper surface of the third conductive layer; a region where an upper surface of the first conductive layer and the third conductive layer are in contact with each other does not overlap with the first semiconductor layer in a cross-sectional view of the first transistor in a channel length direction; the first conductive layer has a different material than the second conductive layer and the third conductive layer; The second conductive layer has the same material as the third conductive layer.

2. A display device having a first transistor and a second transistor, a first insulating layer provided above the substrate; a first conductive layer having a region located above the first insulating layer and functioning as one of a source electrode and a drain electrode of the first transistor; a first semiconductor layer having a region in contact with an upper surface of the first conductive layer and having a channel formation region of the first transistor; a second semiconductor layer having a region located above the first insulating layer and having a channel formation region of the second transistor; a second insulating layer having a region in contact with an upper surface of the first semiconductor layer and including silicon oxide; a second conductive layer having a region in contact with a top surface of the second insulating layer and functioning as one of a source electrode and a drain electrode of the second transistor; a third conductive layer having a region in contact with an upper surface of the second insulating layer and a region in contact with an upper surface of the first conductive layer at an opening in the second insulating layer; a third insulating layer having a region in contact with an upper surface of the second conductive layer and a region in contact with an upper surface of the third conductive layer; a fourth conductive layer having a region overlapping with the first semiconductor layer and functioning as a gate electrode of the first transistor; a fifth conductive layer having a region overlapping with the second semiconductor layer and functioning as a gate electrode of the second transistor; a region where an upper surface of the first conductive layer and the third conductive layer are in contact with each other does not overlap with the first semiconductor layer in a cross-sectional view of the first transistor in a channel length direction; the first conductive layer has a different material than the second conductive layer and the third conductive layer; the second conductive layer has the same material as the third conductive layer; The fourth conductive layer has a different material than the fifth conductive layer.

3. In claim 1 or 2, A display device comprising: a pixel electrode having a region located above the third insulating layer and having a region in contact with the third conductive layer at an opening in the third insulating layer.

Images