Indication device

Abstract

To provide a display device with excellent display quality.SOLUTION: A display device includes a transistor on a substrate, an inorganic insulating film in contact with the transistor, an organic insulating film in contact with the inorganic insulating film, a capacitor element electrically connected to the transistor, and a pixel electrode formed on the organic insulating film and electrically connected to the transistor. The transistor includes a gate electrode on the substrate, an oxide semiconductor film overlapping with the gate electrode, a gate insulating film in contact with one surface of the oxide semiconductor film, and a pair of conductive films in contact with the oxide semiconductor film. The capacitor element includes a metal oxide film on the gate insulating film, an inorganic insulating film, and a conductive film with first light-transmitting property on the inorganic insulating film. The pixel electrode is formed of a conductive film with second light-transmitting property and is in contact with one of the pair of conductive films and the conductive film with the first light-transmitting property.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an article, a method, or a manufacturing method. The invention relates to the manufacture or composition of matter. One embodiment of the present invention is a semiconductor device, a display device, a light-emitting device, a power storage device, and a driving method thereof. In particular, one embodiment of the present invention relates to a semiconductor device having an oxide semiconductor, The present invention relates to a semiconductor device or a display device. [Background technology]

[0002] It is used in many flat panel displays, such as liquid crystal displays and light-emitting displays. The transistors used are made of amorphous silicon and single-crystal silicon formed on a glass substrate. It is made of silicon semiconductor such as silicon or polycrystalline silicon. Transistors using semiconductors are also used in integrated circuits (ICs).

[0003] In recent years, metal oxides that exhibit semiconductor properties have been used in transistors instead of silicon semiconductors. In this specification, metal oxides that exhibit semiconductor properties are referred to as oxides. We will call it a semiconductor.

[0004] For example, a transistor using zinc oxide or an In-Ga-Zn oxide as an oxide semiconductor may be used. A transistor is fabricated and used as a switching element for a pixel of a display device. Techniques have been disclosed (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-123861 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-96055 Summary of the Invention [Problem to be solved by the invention]

[0006] The capacitance element has a pair of electrodes and a dielectric film between them. The other electrode is a gate electrode, a source electrode, a drain electrode, or the like that constitutes a transistor. In many cases, the light-shielding layer is formed of a conductive film having a light-shielding property.

[0007] In addition, in a liquid crystal display device, the larger the capacitance value of the capacitance element, the more the capacitance value of the capacitance element increases. In this case, the period during which the alignment of the liquid crystal molecules in the liquid crystal element can be kept constant can be extended. When displaying a still image, the fact that the period can be extended is a This reduces the number of times, which is expected to reduce power consumption.

[0008] In order to increase the capacitance of a capacitive element, the area occupied by the capacitive element must be increased. However, there is a way to increase the area where the pair of electrodes overlap. In a display device, a conductive film having a light-shielding property is used to increase the area where a pair of electrodes overlap. If the area of ​​the film is increased, the aperture ratio of the pixel decreases, and the display quality of the image deteriorates. This problem is particularly noticeable in high-resolution liquid crystal display devices.

[0009] On the other hand, in a transistor including an oxide semiconductor film, the This leads to a problem that the amount of fluctuation in the electrical characteristics of the transistor, typically the threshold voltage, increases. Furthermore, if a transistor has normally-on characteristics, malfunctions may occur during operation. It may become easier to operate, or power consumption may increase when not in operation, or in the case of a display device, This causes various problems, such as a decrease in cost, which leads to a decrease in display quality.

[0010] In view of this, one embodiment of the present invention provides a display device with excellent display quality. One aspect is a display device having a high aperture ratio and a capacitor whose capacitance value can be increased. Another embodiment of the present invention provides a display device with reduced power consumption. Another embodiment of the present invention provides a display device including a transistor with excellent electrical characteristics. Another aspect of the present invention is to provide a novel display device. To provide a method for manufacturing a display device that has a high aperture ratio and a wide viewing angle with a small number of steps. Another embodiment of the present invention provides a method for manufacturing a novel display device.

[0011] The description of these problems does not preclude the existence of other problems. It is not necessary for one embodiment to solve all of these problems. The subject matter will be self-evident from the description, drawings, claims, etc. It is possible to extract other issues from the drawings, claims, etc. [Means for solving the problem]

[0012] One embodiment of the present invention is a semiconductor device including a transistor over a substrate, an inorganic insulating film in contact with the transistor, and an inorganic insulating film. an organic insulating film in contact with the insulating film, a capacitance element electrically connected to the transistor, and an organic insulating film a pixel electrode formed on the film and electrically connected to the transistor, The transistor includes a gate electrode over a substrate, an oxide semiconductor film overlapping with the gate electrode, and A gate insulating film in contact with one surface of the oxide semiconductor film and a pair of conductive films in contact with the oxide semiconductor film The capacitor element includes a metal oxide film on a gate insulating film, an inorganic insulating film, and an inorganic insulating film. The pixel electrode has a first conductive film having a light-transmitting property on the insulating film. The conductive film is formed of a conductive film and is in contact with one of the pair of conductive films and the first light-transmitting conductive film.

[0013] Another embodiment of the present invention is a transistor over a substrate and an inorganic insulating film in contact with the transistor. an organic insulating film in contact with the inorganic insulating film; a capacitor element electrically connected to the transistor; a pixel electrode formed on the organic insulating film and electrically connected to the transistor; The transistor is a device that has a gate electrode on a substrate and an oxide semiconductor layer that overlaps the gate electrode. a gate insulating film in contact with one surface of the oxide semiconductor film; The capacitor element is formed on the gate insulating film and on one of the pair of conductive films. a metal oxide film in contact with the inorganic insulating film; and a first light-transmitting conductive film on the inorganic insulating film. The pixel electrode is formed of a second light-transmitting conductive film and has a pair of conductive films. Contact with one side.

[0014] The transistor has a gate electrode that overlaps with the oxide semiconductor film with an inorganic insulating film interposed therebetween. The gate electrode may have a dual gate structure in which an oxide film is formed between the gate electrode and the gate insulating film. The semiconductor film may be connected to a gate electrode that overlaps the semiconductor film.

[0015] Note that the inorganic insulating film is formed between the oxide insulating film in contact with the other surface of the oxide semiconductor film and the oxide insulating film. and a nitride insulating film in contact with the film.

[0016] The metal oxide film is formed in contact with the nitride insulating film and is made of the same metal as the oxide semiconductor film. It may contain group elements.

[0017] The oxide semiconductor film may be an In-Ga oxide, an In-Zn oxide, or an In-MnO n oxides (M is Al, Ti, Ga, Y, Zr, Sn, La, Ce, Nd, Sn, or Hf).

[0018] The oxide semiconductor film has a multilayer structure including a first film and a second film, and the first film is The atomic ratio of the metal elements in the second film may be different from that in the first film. [Effects of the Invention]

[0019] According to one embodiment of the present invention, a display device with excellent display quality can be provided. According to one embodiment of the present invention, a capacitor element having a high aperture ratio and capable of increasing a capacitance value is provided. According to one embodiment of the present invention, a display device having low power consumption can be provided. According to one embodiment of the present invention, a display device having excellent electrical characteristics can be provided. According to one embodiment of the present invention, a display device including a transistor can be provided. A display device with a high aperture ratio and a wide viewing angle can be manufactured with a small number of steps. According to one embodiment of the present invention, a novel display device can be provided. The description of these effects does not preclude the existence of other effects. It is not necessary to have all of these effects. Effects other than these may be included in the description. The above is self-evident from the description, drawings, claims, etc. From the above descriptions, it is possible to extract other effects. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 2] 1A and 1B are a block diagram and a circuit diagram illustrating one embodiment of a semiconductor device. [Figure 3] FIG. 1 is a top view illustrating one embodiment of a semiconductor device. [Figure 4] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 5] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 6] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 7] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 8] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 9] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 10] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 11] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 12] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 13] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 14] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 15] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 16] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 17] FIG. 1 is a top view illustrating one embodiment of a semiconductor device. [Figure 18] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 19]1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 20] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 21] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 22] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 23] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 24] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 25] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 26] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 27] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 28] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 29] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 30] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 31] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 32] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 33] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 34] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 35] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 36] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 37] 1A to 1C are cross-sectional views illustrating one embodiment of a method for manufacturing a semiconductor device. [Figure 38] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 39] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 40] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 41] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 42] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 43] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 44] Cs-corrected high-resolution TEM image of a cross section of CAAC-OS, and a schematic cross-sectional diagram of CAAC-OS. [Figure 45] Cs-corrected high-resolution TEM image of the CAAC-OS in the plane. [Figure 46] 10A and 10B illustrate structural analyses of a CAAC-OS and a single-crystal oxide semiconductor by XRD. [Figure 47] Electron diffraction pattern of CAAC-OS. [Figure 48] FIG. 1 shows the change in the crystalline part of an In-Ga-Zn oxide due to electron irradiation. [Figure 49] Schematic diagram illustrating the film formation model of CAAC-OS and nc-OS. [Figure 50] A diagram explaining InGaZnO4 crystals and pellets. [Figure 51] Schematic diagram illustrating a film formation model of CAAC-OS. [Figure 52] A diagram explaining the InGaZnO4 crystal. [Figure 53] A diagram explaining the structure of InGaZnO4 before the atoms collide. [Figure 54] A diagram explaining the structure of InGaZnO4 after the atoms collide. [Figure 55] A diagram explaining the trajectories of atoms after they collide. [Figure 56] Cross-sectional HAADF-STEM images of the CAAC-OS and target. [Figure 57] FIG. 10 is a diagram illustrating the temperature dependence of resistivity. [Figure 58] FIG. 1 is a conceptual diagram illustrating an example of a method for driving a display device. [Figure 59] FIG. 2 is a diagram illustrating a display module. [Figure 60] 1A and 1B are diagrams illustrating external views of an electronic device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following description, and the embodiments and methods thereof may be modified without departing from the spirit and scope of the present invention. It will be readily apparent to those skilled in the art that various modifications may be made to the design and details of the present invention. The present invention should not be construed as being limited to the description of the following embodiments. In the embodiments described below, the same parts or parts having similar functions are designated by the same reference numerals or symbols. Alternatively, the same hatch pattern may be used in common between different drawings, and repeated explanations thereof may be omitted. do.

[0022] In each figure described in this specification, the size of each component, the thickness of the film, or the area is The figures may be exaggerated for clarity and are not necessarily limited to that scale. stomach.

[0023] In addition, terms such as first, second, and third used in this specification are used interchangeably to avoid confusion of components. It is not intended to limit the number of items. The terms "second" or "third" can be used interchangeably to explain the present invention.

[0024] The functions of the "source" and "drain" are also different when the direction of the current changes during circuit operation. For this reason, in this specification, the terms "sauce" and "dressing" are used interchangeably. The terms "in" and "in" may be used interchangeably.

[0025] Voltage refers to the potential difference between two points, and potential refers to the electrostatic field at a certain point. This refers to the electrostatic energy (electrical potential energy) of a unit charge in a particle. However, in general, the potential difference between the potential at a certain point and a reference potential (for example, ground potential) This is simply called potential or voltage, and potential and voltage are often used synonymously. Therefore, in this specification, unless otherwise specified, the term "potential" may be read as "voltage." , voltage may be read as potential.

[0026] In this specification, when an etching step is performed after a photolithography step, The mask formed in the photolithography process is removed.

[0027] In this specification, "parallel" means that two straight lines are arranged at an angle of -10° or more and 10° or less. Therefore, it includes the case of -5° or more and 5° or less. refers to the state in which two straight lines are arranged at an angle of 80° or more and 100° or less. , including cases where the angle is between 85° and 95°.

[0028] In this specification, when the crystal is a trigonal or rhombohedral crystal, it is represented as a hexagonal crystal system. vinegar.

[0029] (Embodiment 1) In this embodiment, a semiconductor device according to one embodiment of the present invention will be described with reference to drawings. .

[0030] FIG. 1 is a cross-sectional view of a transistor 103 and a capacitor 105 included in a semiconductor device.

[0031] The transistor 103 shown in FIG. 1A has a gate electrode provided over a substrate 302. A functional conductive film 304c and a gate insulating film formed on the substrate 302 and the conductive film 304c. 51, an oxide semiconductor film 308b overlapping with the conductive film 304c with the gate insulating film 51 interposed therebetween, a pair of electrodes functioning as a source electrode and a drain electrode in contact with the oxide semiconductor film 308b; The conductive film 310d includes conductive films 310e.

[0032] In addition, a metal oxide film 308c is provided on the gate insulating film 51. An inorganic insulating film 53 is provided on the insulating film 53. The metal oxide film 308c, the inorganic insulating film 53, and the conductive film 316b are provided. The capacitance element 105 is formed by 16b.

[0033] In addition, an organic insulating film 317 is provided on the inorganic insulating film 53 and the conductive film 316b. In addition, in the openings provided in the inorganic insulating film 53 and the organic insulating film 317, the conductive film 310e A conductive film 319 connected to the conductive film 316b is provided on the organic insulating film 317. The film 319 functions as a pixel electrode.

[0034] The metal oxide film 308c is an oxide semiconductor film formed at the same time as the oxide semiconductor film 308b. hydrogen, boron, phosphorus, nitrogen, tin, antimony, rare gas elements, alkali metals, alkalis By introducing impurities such as lithium-earth metals or oxygen deficiencies, the conductivity is improved, and the conductive Since the oxide semiconductor film has a light-transmitting property, the metal oxide film 3 08c is also translucent.

[0035] The conductive film 316b and the conductive film 319 are formed using a light-transmitting conductive film. Therefore, the capacitor 105 has a light-transmitting property. It is possible to reduce the capacitance of the capacitor element and increase the aperture ratio of the pixel. .

[0036] The inorganic insulating film 53 includes at least an oxide insulating film, and further includes an oxide insulating film and a nitride insulating film. In the inorganic insulating film 53, the oxide semiconductor film 30 is preferably laminated. The oxide insulating film is formed in the region in contact with the oxide semiconductor film 308b. It is possible to reduce the number of defects at the interface between the inorganic insulating film 53 and the silicon dioxide film 54.

[0037] The nitride insulating film also functions as a barrier film against water, hydrogen, and the like. When water, hydrogen, or the like is contained in the oxide semiconductor film 308b, the oxygen contained in the oxide semiconductor film 308b and the water, hydrogen, or the like are mixed. As a result, oxygen vacancies are formed in the oxide semiconductor film 308b. Carriers are generated in the oxide semiconductor film 308b, and the threshold voltage of the transistor decreases. This results in a negative shift, and the transistor becomes normally on. By providing the nitride insulating film as the film 53, water and water from the outside can be prevented from entering the oxide semiconductor film 308b. The amount of diffusion of elements and the like can be reduced, and the number of defects in the oxide semiconductor film 308b can be reduced. Therefore, in the inorganic insulating film 53, the oxide semiconductor film 308b side The oxide insulating film and the nitride insulating film are stacked in this order, whereby the oxide semiconductor film 308b and and the inorganic insulating film 53, and oxygen vacancies in the oxide semiconductor film 308b. It is possible to reduce the amount of GaN and fabricate a transistor with normally-off characteristics. It is Noh.

[0038] The organic insulating film 317 is made of organic resin such as acrylic resin, polyimide resin, or epoxy resin. The thickness of the organic insulating film 317 is 500 nm or more. 0 nm or less, preferably 1000 nm or more and 3000 nm or less.

[0039] The conductive film 319 formed on the organic insulating film 317 is a conductive film for the transistor 103 and the capacitor 104. The conductive film 319 functions as a pixel electrode and is connected to the inorganic insulating film 53 and the organic insulating film 105. The conductive layer 317 is connected to the transistor 103 through an opening formed in the conductive insulating layer 317. The film 319 is located at a distance from the transistor 103, and therefore the conductive property of the transistor 103 is As a result, the conductive film 319 is not easily affected by the potential of the film 310d. They can be overlapped, which increases the aperture ratio of the pixel.

[0040] As a comparative example, a transistor in which the organic insulating film 317 is not formed on the inorganic insulating film 53 is used. In a semiconductor device having a transistor 103, The case where a negative voltage is applied to the conductive film 304c will be described.

[0041] When a negative voltage is applied to the conductive film 304c functioning as a gate electrode, an electric field is generated. The electric field is not blocked by the oxide semiconductor film 308b and affects the inorganic insulating film 53. A weak positive charge is applied to the surface of the inorganic insulating film 53. When a negative voltage is applied to the inorganic insulating film 304c, positively charged particles contained in the air are transferred to the inorganic insulating film 5. 3, and the surface of the inorganic insulating film 53 is charged with a weak positive charge.

[0042] Positive charges are applied to the surface of the inorganic insulating film 53, generating an electric field, which then forms an oxide film. This affects the interface between the semiconductor film 308b and the inorganic insulating film 53. As a result, the oxide semiconductor film 3 A positive bias is applied to the interface between the insulating film 53 and the insulating film 58. As a result, the threshold voltage of the transistor shifts negatively.

[0043] On the other hand, the transistor 103 according to this embodiment shown in FIG. 1 has an organic insulating film on an inorganic insulating film 53. The organic insulating film 317 has a thickness of 500 nm or more. This occurs when a negative voltage is applied to the conductive film 304c that functions as a gate electrode. The influence of the electric field does not reach the surface of the organic insulating film 317, and a positive electric field is applied to the surface of the organic insulating film 317. In addition, the organic insulating film 317 has a thickness of 500 nm or more. Even if positively charged particles contained in the air are adsorbed on the surface of the organic insulating film 317, the organic insulating film The electric field of the positively charged particles adsorbed on the surface of the oxide semiconductor film 308b and the inorganic insulating film 317 As a result, the oxide semiconductor film 308b and the inorganic insulating film 53 are hardly affected. At the interface of 3, a positive bias is not applied substantially, and the transistor The fluctuation of the threshold voltage is small.

[0044] In addition, water and the like easily diffuse into the organic insulating film 317, but the inorganic insulating film 53 is made of a nitride. By having an insulating film, the nitride insulating film acts as a barrier film for water, preventing it from diffusing into the organic insulating film 317. This can prevent the water from diffusing into the oxide semiconductor film 308b.

[0045] From the above, by providing the organic insulating film 317 on the transistor, It is possible to reduce variations in electrical characteristics. In addition, it has normally-off characteristics and high reliability. In addition, the organic insulating film can be formed by a printing method or a coating method. Since it is possible to form the film using a material such as a silicon dioxide, the manufacturing time can be reduced. By providing a conductive film that functions as a pixel electrode on the organic insulating film 317, You can increase your speaking rate.

[0046] <Variation 1> A modification of the transistor described in this embodiment 1 will be described with reference to FIG. The transistor 103 in this modification is a transistor including an oxide semiconductor film formed using a multi-tone mask. 308e and a pair of conductive films 310f and 310g.

[0047] By using a multi-tone mask, it is possible to form resist masks with multiple thicknesses. After the oxide semiconductor film 308e is formed using the resist mask, oxygen plasma By exposing the resist mask to a mask or the like, a part of the resist mask is removed, and a pair of conductive films are formed. Therefore, the oxide semiconductor film 308e and the pair of conductive films 308c are formed as a resist mask. The number of photolithography steps in the process of manufacturing the conductive films 310f and 310g can be reduced. can.

[0048] Note that the top surface of the oxide semiconductor film 308e formed using the multi-tone mask has a shape similar to that of a pair of conductive films. The conductive films 310f and 310g are partially protruding from the outside.

[0049] <Variation 2> In the display device shown in the first embodiment, in some cases or depending on the situation, for example, For example, the conductive film 319 may be formed using a conductive film that has a function of reflecting light. Alternatively, the conductive film 319 may be formed using a laminated film, and at least one of the laminated films may be formed using a conductive film. Alternatively, a conductive film having a function of reflecting light may be used. Examples of materials include silver, aluminum, chromium, copper, tantalum, titanium, molybdenum, Tungsten or the like can be used. Alternatively, the conductive film 319 can be formed using silver. The laminated film is sandwiched between indium tin oxide (hereinafter referred to as ITO) films. In such a case, a reflective display device, a semi-transmissive display device, a This embodiment can be applied to a light emitting device with a top emission structure.

[0050] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0051] (Embodiment 2) In this embodiment, a semiconductor device according to one embodiment of the present invention and a manufacturing method thereof will be described with reference to drawings. Please refer to the following for explanation.

[0052] FIG. 2A shows a display device as an example of a semiconductor device. The display device shown in FIG. The pixel section 11, the scanning line driving circuit 14, and the signal line driving circuit 16 are arranged in parallel or substantially parallel relation. m scanning lines 17 arranged in rows and having potentials controlled by a scanning line driving circuit 14; The signals are arranged parallel or approximately parallel to each other, and the potentials are controlled by a signal line driving circuit 16. and n signal lines 19. Furthermore, the pixel section 11 has a plurality of pixels arranged in a matrix. The pixel 301 is arranged parallel or substantially parallel to the signal line 19. The capacitance lines 25 are arranged parallel or substantially parallel to the scanning lines 17. The scanning line driving circuit 14 and the signal line driving circuit 16 may be arranged in rows. This may be referred to as a drive circuit section.

[0053] The display device includes a driver circuit for driving a plurality of pixels. Control circuit, power supply circuit, signal generating circuit, backlight module, etc. arranged on the substrate It is sometimes called a liquid crystal module.

[0054] Each scanning line 17 is connected to any one of the pixels 301 arranged in m rows and n columns in the pixel section 11. Each signal line 19 is electrically connected to n pixels 301 arranged in a row. Among the pixels 301 arranged in n rows and n columns, m pixels 301 arranged in any one of the columns are energized. Both m and n are integers equal to or greater than 1. Each capacitance line 25 has m rows. Among the pixels 301 arranged in n columns, n pixels 301 arranged in any row are electrically connected to The capacitance lines 25 are arranged parallel or substantially parallel to the signal lines 19. If the pixel 301 is arranged in m rows and n columns, the pixel 301 is arranged in any one of the columns. The pixel 301 is electrically connected to the m pixels 301 .

[0055] Here, one pixel is an area surrounded by scanning lines and signal lines and showing one color. Therefore, in the case of a color display device consisting of the color elements R (red), G (green), and B (blue), In this case, the minimum unit of an image is made up of three pixels: an R pixel, a G pixel, and a B pixel. In addition, pixels such as yellow, cyan, and magenta can be added to R (red), G (green), and B (blue). This allows for improved color reproducibility. Also, in addition to R (red), G (green), and B (blue), W (white) By adding these pixels, the power consumption of the display device can be reduced. In this case, by adding a W (white) pixel to each of R (red), G (green), and B (blue), the LCD This allows the brightness of the backlight to be reduced. This makes it possible to reduce the power consumption of the liquid crystal display device.

[0056] 2B and 2C can be used for the pixel 301 of the display device shown in FIG. 2A. 2 shows an example of a circuit configuration.

[0057] The pixel 301 shown in FIG. 2B includes a liquid crystal element 31, a transistor 103, and a capacitor 1 05 and has.

[0058] The potential of one of the pair of electrodes of the liquid crystal element 31 is set appropriately according to the specifications of the pixel 301. The orientation state of the liquid crystal element 31 is set by the written data. A common potential (common potential) is applied to one of the pair of electrodes of the liquid crystal element 31 in each of the liquid crystal elements 301. Alternatively, a different voltage may be applied to one of the pair of electrodes of the liquid crystal element 31 for each pixel 301 in each row. A potential may be applied.

[0059] The liquid crystal element 31 controls the transmission or non-transmission of light by the optical modulation action of the liquid crystal. The optical modulation effect of the liquid crystal is achieved by the electric field applied to the liquid crystal (horizontal electric field, vertical electric field). The liquid crystal element 31 is controlled by a vertical electric field (including a diagonal electric field or an oblique electric field). , nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, thermotropic liquid crystal, Examples include iotropic liquid crystal, ferroelectric liquid crystal, and antiferroelectric liquid crystal.

[0060] The display device having the liquid crystal element 31 can be driven in, for example, TN mode or VA mode. , ASM(Axially Symmetric Aligned Micro-cel l) mode, OCB (Optically Compensated Birefringence Gence mode, MVA mode, PVA (Patterned Vertical Alignment) mode, IPS mode, FFS mode, or TBA (Trans You can also use the (Verse Bend Alignment) mode. The present invention is not limited to the above, and various liquid crystal elements and driving methods thereof can be used.

[0061] Also, a liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent The liquid crystal element may be configured by the following. The liquid crystal that exhibits the blue phase has a response speed of 1 msec or less. Since it is short and optically isotropic, alignment treatment is not required and viewing angle dependency is small.

[0062] In the configuration of the pixel 301 shown in FIG. 2B, the source electrode and the drain electrode of the transistor 103 One of the drain electrodes is electrically connected to the signal line 19, and the other is a pair of electrodes of the liquid crystal element 31. The gate electrode of the transistor 103 is electrically connected to the other of the scan lines 17. The transistor 103 is electrically connected to the , and has a function of controlling the writing of data of the data signal.

[0063] In the configuration of the pixel 301 shown in FIG. 2B, one of a pair of electrodes of the capacitor 105 is The other end is electrically connected to a capacitor line 25 to which a potential is supplied, and the other end is connected to one of the pair of electrodes of the liquid crystal element 31. The potential value of the capacitance line 25 is set to a value according to the specifications of the pixel 301. The capacitance element 105 functions as a storage capacitor that stores written data. Possess the ability.

[0064] For example, in a display device having the pixel 301 shown in FIG. 2B, the scanning line driving circuit 14 The pixels 301 in the row are selected in sequence, and the transistors 103 are turned on to output the data signal. Write.

[0065] The pixel 301 to which the data has been written is retained by turning off the transistor 103. By repeating this process for each row, an image can be displayed.

[0066] The pixel 301 shown in FIG. 2C includes a transistor 4 that switches the display element. 3, a transistor 103 for controlling pixel driving, a transistor 45, and a capacitor element 10 5 and a light-emitting element 41.

[0067] One of the source electrode and the drain electrode of the transistor 43 is connected to a signal line to which a data signal is applied. The gate electrode of transistor 43 is electrically connected to line 19. is electrically connected to a scan line 17 to which a signal is applied.

[0068] The transistor 43 is turned on or off to transmit the data of the data signal. It has the function of controlling the writing of

[0069] One of the source electrode and the drain electrode of the transistor 103 functions as an anode line. The wiring 47 is electrically connected to the source electrode and the drain electrode of the transistor 103. The other electrode of the transistor 103 is electrically connected to one electrode of the light-emitting element 41. The gate electrode is connected to the other of the source electrode and the drain electrode of the transistor 43 and the capacitor element 1. 05 is electrically connected to one electrode of the

[0070] The transistor 103 is turned on or off to allow current to flow to the light emitting element 41. It has the function of controlling the current flowing through it.

[0071] One of the source and drain electrodes of the transistor 45 is given a data reference potential. The other of the source electrode and the drain electrode of the transistor 45 is connected to a wiring 49 through which light is emitted. One electrode of the element 41 and the other electrode of the capacitor 105 are electrically connected to each other. The gate electrode of the transistor 45 is electrically connected to the scanning line 17 to which a gate signal is applied. will be done.

[0072] The transistor 45 has a function of adjusting the current flowing through the light-emitting element 41. When the internal resistance of the light emitting element 41 increases due to deterioration of the light emitting element 41, the transistor 45 The current flowing through the wiring 49 to which one of the source electrode and the drain electrode of the By doing so, the current flowing through the light emitting element 41 can be corrected. The potential can be set to 0V, for example.

[0073] One of a pair of electrodes of the capacitor 105 is connected to the gate electrode of the transistor 103 and the The other of the source electrode and the drain electrode of the capacitor 105 is electrically connected to the The other of the pair of electrodes is connected to the other of the source electrode and drain electrode of the transistor 45 and the light emitting It is electrically connected to one electrode of the element 41 .

[0074] In the configuration of the pixel 301 shown in FIG. 2C, the capacitor 105 It functions as a storage capacitor to store the

[0075] One of the pair of electrodes of the light emitting element 41 is a source electrode and a drain electrode of the transistor 45. the other side of the capacitor 105, and the source electrode and drain electrode of the transistor 103. The other of the pair of electrodes of the light emitting element 41 is electrically connected to the other of the pair of electrodes. The wiring 50 functions as a signal processing circuit.

[0076] The light-emitting element 41 may be, for example, an organic electroluminescence element (also called an organic EL element). However, the light emitting element 41 is not limited to this, and An inorganic EL element made of organic materials may also be used.

[0077] A high power supply potential VDD is applied to one of the wiring 47 and the wiring 50, and a low power supply potential VDD is applied to the other. In the configuration shown in FIG. 2C, a high power supply potential VSS is applied to the wiring 47. VDD is applied to the wiring 50, and a low power supply potential VSS is applied to the wiring 51.

[0078] In the display device having the pixel 301 of FIG. 2C, the pixel of each row is driven by the scanning line driving circuit 14. 301 are selected in sequence, and the transistor 43 is turned on to write the data of the data signal. .

[0079] The pixel 301 into which the data has been written is in a holding state when the transistor 43 is turned off. Furthermore, since the transistor 43 is connected to the capacitor 105, The data stored in the memory can be held for a long time. The amount of current flowing between the source electrode and the drain electrode of the transistor 103 is controlled, and the light emitting element 41 The pixels emit light at a brightness that corresponds to the amount of current flowing through them. By doing this for each row in turn, an image is displayed. It can be shown.

[0080] In addition, in FIG. 2B and FIG. 2C, the liquid crystal element 31 and the light emitting element 41 are used as the display element. However, one aspect of the embodiment of the present invention is not limited to this. It is also possible to use an element. For example, an EL (electroluminescence) element (organic EL elements including organic and inorganic materials, organic EL elements, inorganic EL elements), LEDs (white LEDs, red color LED, green LED, blue LED, etc.), transistor (transistor that emits light according to the current Electron emitter, liquid crystal element, electronic ink, electrophoretic element, grating light Valve (GLV), Plasma Display (PDP), MEMS (Micro Electro Mechanical Systems) Mechanical system), Digital Micromirror Device (DMD), DMS (Digital Micro Shutter), IMOD (Interference Modulation) element, electrowetting element, piezoelectric ceramic display, carbon nanotube The contrast, brightness, reflectance, transmittance, etc. change due to electromagnetic effects, such as An example of a display device using an EL element is an EL display. An example of a display device using electron-emitting devices is a field emission display. Flat panel display (FED) or SED (Surface Emitting Diode) type e-conduction Electron-emitter Display) etc. An example of a display device using a liquid crystal element is a liquid crystal display (transmission type liquid crystal display). Spray, transflective LCD, reflective LCD, direct view LCD Display devices using electronic ink or electrophoretic elements include: An example of such a device is electronic paper.

[0081] Next, a specific configuration of the element substrate included in the display device will be described. A VA type liquid crystal display device is used as the device, and the upper surface of a pixel 301 included in the liquid crystal display device The diagram is shown in Figure 3.

[0082] In FIG. 3, the conductive film 304c functioning as a scanning line is a conductive film 304b functioning as a signal line. The conductors functioning as signal lines extend in a direction substantially perpendicular to the The conductive film 310d and the capacitance line 310i are arranged in a direction substantially perpendicular to the conductive film functioning as the scanning line (see FIG. The conductive film 304c that functions as a scanning line is provided so as to extend in the vertical direction. , which are electrically connected to the scanning line driving circuit 14 (see FIG. 2) and function as signal lines. The conductive film 310d is electrically connected to the signal line driving circuit 16 (see FIG. 2).

[0083] The transistor 103 includes a conductive film serving as a scan line and a conductive film serving as a signal line. The transistor 103 is provided in a region where the gate electrodes are connected. a gate insulating film (not shown in FIG. 3), a channel formed on the gate insulating film, The oxide semiconductor film 308b in which the hole region is formed functions as a source electrode and a drain electrode. The conductive film 304c is formed of a pair of conductive films 310d and 310e. The region overlapping with the oxide semiconductor film 308b also functions as a conductive film. 3, the gate electrode of the transistor 103 functions as a scanning line. The conductive film has an edge portion located outside the edge portion of the oxide semiconductor film 308b in a top view. For this reason, the conductive film that functions as the scanning line is a light-shielding film that blocks light from a light source such as a backlight. As a result, the oxide semiconductor film 308b included in the transistor is irradiated with light. Therefore, fluctuations in the electrical characteristics of the transistor can be suppressed.

[0084] In addition, a conductive film 316b is provided over the metal oxide film 308c with an insulating film interposed therebetween. In addition, an opening indicated by a dashed line is formed in the insulating film provided on the metal oxide film 308c. In the opening 362, the metal oxide film 308c is formed as an insulating film. The insulating film is in contact with the nitride insulating film (not shown in FIG. 3) included in the insulating film.

[0085] The capacitor 105 is formed in a region where the metal oxide film 308c and the conductive film 316b overlap each other. The metal oxide film 308c and the conductive film 316b have light-transmitting properties. has light-transmitting properties.

[0086] The conductive film 319 that functions as a pixel electrode is connected to the organic insulating film (not shown in FIG. 3) via the organic insulating film. The conductive film 319 is provided on the conductive film 310e and the conductive film 316b. 4c and the conductive film 310e, and the conductive film 316b at the opening 364d. That is, the transistor 103, the capacitor 105, and the conductive film 319 are electrically connected. do.

[0087] Since the capacitor 105 has a light-transmitting property, the capacitor 105 can be made large (large surface area) in the pixel 301. Therefore, it is possible to increase the aperture ratio, typically 50% or more, and It is possible to obtain a display device with an increased capacitance value, and the capacitance can be increased to 60% or more. For example, in a high-resolution display device, such as a liquid crystal display device, the pixel surface Therefore, in a high-resolution display device, Therefore, the capacitance value stored in the capacitive element is reduced. Since the element 105 has a light-transmitting property, by providing the capacitor element in the pixel, It is possible to increase the aperture ratio while obtaining a sufficient capacitance value. Typically, the pixel density is 200p. High resolution display devices with a resolution of 300 ppi or more, or even 500 ppi or more It can be suitably used in such a location.

[0088] In addition, in a liquid crystal display device, the larger the capacitance value of the capacitance element, the more the capacitance value of the capacitance element increases. In this case, the period during which the alignment of the liquid crystal molecules in the liquid crystal element can be kept constant can be extended. When displaying a still image, the period can be extended, reducing the number of times the image data is rewritten. It is possible to reduce the number of circuits, and power consumption can be reduced. The structure shown in FIG. 1 allows the aperture ratio to be increased even in high-resolution display devices. Light from light sources such as backlights can be used efficiently, reducing the power consumption of display devices It is possible.

[0089] Next, a cross-sectional view taken along the dashed line CD in FIG. 3 is shown in FIG. 4. A driving circuit section (top view omitted) including a scanning line driving circuit 14 and a signal line driving circuit 16 The cross-sectional view is shown in AB. In this embodiment, a VA type liquid crystal display is used as the semiconductor device. The display device will be described.

[0090] The liquid crystal display device described in this embodiment has a liquid crystal display device between a pair of substrates (a substrate 302 and a substrate 342). The element 322 is sandwiched.

[0091] The liquid crystal element 322 is made up of a conductive film 316b above the substrate 302 and a film for controlling the orientation (hereinafter referred to as , alignment films 320 and 352), a liquid crystal layer 321, and a conductive film 350. The conductive film 316b functions as one electrode of the liquid crystal element 322, and the conductive film 350 functions as a liquid crystal It serves as the other electrode of the element 322 .

[0092] Thus, a liquid crystal display device is a device that has a liquid crystal element. The device includes a driving circuit for driving a plurality of pixels. a control circuit, a power supply circuit, a signal generating circuit, a backlight module, etc., arranged in It is also called an LCD module.

[0093] In the driving circuit section, a conductive film 304a functioning as a gate electrode, a gate insulating film 51, and the insulating film 305 and the insulating film 306 that function as a channel region; and the oxide semiconductor film in which the channel region is formed. 308a, and conductive films 310a and 310b functioning as source and drain electrodes. The oxide semiconductor film 308a forms the transistor 102. can be done.

[0094] In the pixel portion, a conductive film 304c serving as a gate electrode and a gate insulating film 51 The insulating film 305 and the insulating film 306 function, and the channel region formed on the gate insulating film 51 the oxide semiconductor film 308b, which is formed with a conductive layer serving as a source electrode and a drain electrode; The films 310d and 310e constitute the transistor 103. The oxide semiconductor film 308b , are provided on the gate insulating film 51. In addition, inorganic insulating films are provided on the conductive films 310d and 310e. The insulating films 312 and 314, which are the film 53, are provided as protective films.

[0095] Also, a metal oxide film 308c functions as one electrode, and an insulating film functions as a dielectric film. The film 314 and the conductive film 316b functioning as the other electrode form a capacitor 105. The metal oxide film 308c is provided on the gate insulating film 51.

[0096] An organic insulating film 317 is formed on the inorganic insulating film 53. In addition, on the organic insulating film 317, A conductive film 319 that functions as a pixel electrode is formed. are connected by a conductive film 319.

[0097] In the driving circuit section, the conductive film 304a and the conductive film 304c are formed at the same time. 4b and the conductive film 31 formed simultaneously with the conductive films 310a, 310b, 310d, and 310e. The conductive film 319 is connected to the electrode 0c through a conductive film 319a formed at the same time as the conductive film 319.

[0098] The conductive film 304a and the conductive film 319a are formed by the insulating film 305, the insulating film 306, the insulating film 312, The conductive film 310c and the conductive film 310d are connected to each other through an opening provided in the organic insulating film 317. The conductive film 319a is formed through an opening provided in the insulating film 312, the insulating film 314, and the organic insulating film 317. Connect at the part.

[0099] The components of the display device shown in FIG. 4 will now be described.

[0100] Conductive films 304a, 304b, and 304c are formed on the substrate 302. The conductive film 04a functions as a gate electrode of a transistor in the driver circuit portion. The conductive film 304b is formed in the driving circuit section and is connected to the conductive film 310c. is formed in the pixel section 11 and functions as a gate electrode of the transistor in the pixel section.

[0101] There is no particular restriction on the material of the substrate 302, but it should be strong enough to withstand the subsequent heat treatment. For example, glass substrates, ceramic substrates, quartz substrates, and A fire substrate or the like may be used as the substrate 302. Also, silicon or silicon carbide may be used. A single crystal semiconductor substrate, a polycrystalline semiconductor substrate, a silicon germanium substrate, or the like is used as a material. It is also possible to apply a compound semiconductor substrate, an SOI substrate, etc., and a semiconductor element is formed on these substrates. A substrate provided with a substrate may be used as the substrate 302. When using a substrate, the 6th generation (1500mm x 1850mm) and 7th generation (1870mm) m x 2200mm), 8th generation (2200mm x 2400mm), 9th generation (2400m 10th generation (2950mm x 3400mm) and large area substrates This makes it possible to manufacture a large-sized liquid crystal display device.

[0102] In addition, a flexible substrate is used as the substrate 302, and a transistor is formed directly on the flexible substrate. Alternatively, a separation layer may be provided between the substrate 302 and the transistor. After completing a part or all of the element part on it, it is separated from the substrate 302 and mounted on another substrate. In this case, the transistor can be mounted on a substrate with poor heat resistance or a flexible substrate. It can also be reproduced on boards.

[0103] The conductive films 304a, 304b, and 304c may be made of aluminum, chromium, copper, or tantalum. , titanium, molybdenum, tungsten, or the metal elements mentioned above. It can be formed using an alloy containing the above-mentioned metal elements or an alloy combining the above-mentioned metal elements. In addition, the present invention uses a metal element selected from one or more of manganese and zirconium. The conductive films 304a, 304b, and 304c may have a single-layer structure or a two-layer or more structure. For example, a single layer structure of an aluminum film containing silicon, an aluminum film containing silicon, or a silicon-containing aluminum film may be used. Two-layer structure in which a titanium film is laminated on a titanium nitride film, two-layer structure in which a titanium film is laminated on a titanium nitride film, Two-layer structure in which a tungsten film is laminated on a titanium nitride film, a tantalum nitride film or a tungsten nitride film Two-layer structure with tungsten film stacked on stainless film, titanium film and aluminum film on the titanium film There are three-layer structures, such as a laminated aluminum film and a titanium film on top of that. Titanium, tantalum, tungsten, molybdenum, chromium, neodymium, scandium Alternatively, an alloy film made of a combination of one or more selected from the group consisting of aluminum and nitride may be used.

[0104] The conductive films 304a, 304b, and 304c are made of indium tin oxide or tungsten oxide. Indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, titanium oxide Indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide A conductive material having light-transmitting properties, such as indium tin oxide doped with silicon oxide, is used. In addition, a laminate structure of the above-mentioned light-transmitting conductive material and the above-mentioned metal element can be used. It is also possible.

[0105] An insulating film 305, an insulating film 306, an insulating film 307, an insulating film 308, an insulating film 309, an insulating film 309a, an insulating film 309c, and an insulating film 309b are formed on the substrate 302 and the conductive films 304a, 304c, and 304b. The insulating film 305 and the insulating film 306 are formed on the transistors in the driver circuit section. The gate insulating film 51 functions as the gate insulating film 51 of the transistor in the pixel section 11. do.

[0106] The insulating film 305 may be, for example, a silicon nitride film, a silicon nitride oxide film, or an aluminum nitride film. It is preferable to form the insulating film using a nitride insulating film such as an aluminum film or an aluminum nitride oxide film.

[0107] The insulating film 306 may be, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, Silicon nitride, aluminum oxide, hafnium oxide, gallium oxide or Ga-Zn based gold The insulating film 306 may be formed using a metal oxide or the like, and may be formed as a stacked layer or a single layer. Hafnium silicate (HfSiO x ), nitrogen-doped hafnium silicate HfSi x O y N z ), nitrogen-doped hafnium aluminate (HfAl x O y N z ), hafnium oxide, yttrium oxide, and other high-k materials. This reduces the gate leakage of the transistor.

[0108] The total thickness of the insulating film 305 and the insulating film 306 is preferably 5 nm or more and 400 nm or less. Preferably, the thickness is 10 nm or more and 300 nm or less, and more preferably, 50 nm or more and 250 nm or less. It is good.

[0109] Oxide semiconductor films 308a and 308b and a metal oxide film 308c are formed over the insulating film 306. The oxide semiconductor film 308a is formed so as to overlap with the conductive film 304a. The oxide semiconductor film 308 functions as a channel region of a transistor in the driver circuit portion. b is formed in a position overlapping with the conductive film 304c, and is a channel region of a transistor in a pixel portion. The metal oxide film 308c functions as one electrode of the capacitor 105. .

[0110] The oxide semiconductor films 308a and 308b and the metal oxide film 308c are typically made of In -Ga oxide film, In-Zn oxide film, In-M-Zn oxide film (M is Al, Ti, G The oxide semiconductor film 30 may be formed of any of the following metals: yttrium, zirconium, lanthanum, cerium, neodymium, tin, and hafnium. The metal oxide film 8a, 308b, and the metal oxide film 308c are light-transmitting.

[0111] Note that the oxide semiconductor films 308a and 308b and the metal oxide film 308c are In-MZ When the sum of In and M is 100 atomic %, The atomic ratio is In greater than 25 atomic % and M less than 75 atomic %. More preferably, In is higher than 34 atomic % and M is less than 66 atomic %.

[0112] The oxide semiconductor films 308a and 308b and the metal oxide film 308c have an energy gap. The voltage is 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. As shown in Fig. 1, by using an oxide semiconductor with a wide energy gap, the off-state current of a transistor can be reduced. can be reduced.

[0113] The oxide semiconductor films 308a and 308b and the metal oxide film 308c each have a thickness of 3 nm or more. 200 nm or less, preferably 3 nm or more and 100 nm or less, and more preferably 3 nm or more and 5 0 nm or less.

[0114] The oxide semiconductor films 308a and 308b and the metal oxide film 308c are made of In:Ga:Z n=1:1:1, In:Ga:Zn=1:1:1.2, or 3:1:2 atomic ratio I The oxide semiconductor films 308a and 308b can be made of n-Ga-Zn oxide. The atomic ratios of the metal oxide film 308c and the metal oxide film 308d are each a sum of the atomic ratios mentioned above plus an error. Includes a minus 20% fluctuation.

[0115] The oxide semiconductor films 308a and 308b and the metal oxide film 308c may be formed, for example, by a non-single-layer structure. The non-single crystal structure may be, for example, a CAAC-OS (C Axis Coupling) structure, which will be described later. Aligned Crystalline Oxide Semiconductor) , polycrystalline structure, microcrystalline structure (described later), or amorphous structure. The amorphous structure has the highest density of defect states, while the CAAC-OS has the lowest density of defect states. The oxide semiconductor films 308a and 308b and the metal oxide film 308c have the same crystallinity. do.

[0116] Note that the oxide semiconductor films 308a and 308b and the metal oxide film 308c have an amorphous structure. region, microcrystalline region, polycrystalline region, CAAC-OS region, single crystal region The mixed film may have two or more types of regions. The region may be a crystalline structure region, a polycrystalline structure region, a CAAC-OS region, or a single-crystalline structure region. In addition, the mixed film may have a single layer structure having two or more regions, for example, an amorphous structure. region, microcrystalline region, polycrystalline region, CAAC-OS region, single crystal region In some cases, the film may have a laminated structure of two or more of the above-mentioned regions.

[0117] The oxide semiconductor films 308a and 308b contain silicon or carbon, which is one of the Group 14 elements. When the oxide semiconductor films 308a and 308b contain oxygen, the amount of oxygen vacancies increases. Therefore, silicon and carbon in the oxide semiconductor films 308a and 308b are The concentration (obtained by secondary ion mass spectrometry) was 2 × 10 18 atoms / cm 3 Less than or equal to 2 x 10 17 atoms / cm 3 The following applies.

[0118] In addition, the oxide semiconductor films 308a and 308b were analyzed by secondary ion mass spectrometry. The concentration of alkali metals or alkaline earth metals in the solution is 1×10 18 atoms / cm 3 Below Below, preferably 2 x 10 16 atoms / cm 3 The following are alkali metals and alkalis: When earth metals bond with oxide semiconductors, they can generate carriers, which can be used in transistors. Therefore, the off-state current of the oxide semiconductor films 308a and 308b may increase. It is preferable to reduce the concentration of alkali or alkaline earth metals.

[0119] When nitrogen is contained in the oxide semiconductor films 308a and 308b, the electrons acting as carriers This increases the carrier density and makes it easier to become n-type. Transistors using oxide semiconductors tend to be normally-on. It is preferable that the amount of nitrogen in the semiconductor film is reduced as much as possible. The nitrogen concentration obtained by mass spectrometry is 5×10 18 atoms / cm 3 Do the following It is preferable that:

[0120] The oxide semiconductor films 308a and 308b are formed using oxide semiconductor films with low carrier density. For example, the oxide semiconductor films 308a and 308b have a carrier density of 1×10 17 pieces / cm 3 Less than 1 × 10 15 pieces / cm 3 or less, more preferably 1 × 10 13 pieces / cm 3 Less than or equal to 1×10 11 pieces / cm 3 The following oxide semiconductor film is used.

[0121] However, the semiconductor characteristics and electrical characteristics (field effect) of the required transistors are not limited to these. It is sufficient to use an appropriate composition depending on the required properties (e.g., the mobility, threshold voltage, etc.). In order to obtain semiconductor characteristics of the transistor, the carrier The density, impurity concentration, defect density, atomic ratio of metal elements to oxygen, interatomic distance, density, etc. are appropriately determined. It is preferable to use such a material.

[0122] The oxide semiconductor films 308a and 308b are formed by forming oxide semiconductor films such as the insulating film 306 and the insulating film 312. Since it is in contact with a film made of a material that can improve the interface characteristics with the conductor film, it is The oxide semiconductor films 308a and 308b function as semiconductors. The transistor having 08b has excellent electrical characteristics.

[0123] Note that the oxide semiconductor films 308a and 308b have a low impurity concentration and a low density of defect states. By using a low-temperature oxide semiconductor film, a transistor with excellent electrical characteristics can be manufactured. Here, the impurity concentration is low and the defect level density is low (the amount of oxygen vacancies is small). High purity authentic or substantially high purity authentic. Intrinsic oxide semiconductors have a low carrier density because they have few carrier generation sources. Therefore, a transistor in which a channel region is formed in the oxide semiconductor film can be formed. The transistor has electrical characteristics in which the threshold voltage is negative (also called normally on). In addition, oxide semiconductors that are high-purity intrinsic or substantially high-purity intrinsic may be used. Since the conductor film has a low defect level density, the trap level density may also be low. An oxide semiconductor film that is pure intrinsic or substantially highly pure intrinsic has an extremely small off-state current. Channel width is 1x10 6 Even if the device has a channel length L of 10 μm, the source electrode and When the voltage between the drain electrodes (drain voltage) is in the range of 1V to 10V, the off-state current is Below the measurement limit of the semiconductor parameter analyzer, i.e., 1×10 -13 A or below characteristic Therefore, a transistor having a channel region formed in the oxide semiconductor film can be obtained. The variation in electrical characteristics of such transistors is small, and they can be highly reliable. Charges trapped in the trap states of the oxide semiconductor film take a long time to disappear. Therefore, oxides with high trap level density can behave as if they are fixed charges. Transistors in which the channel region is formed in a semiconductor film may have unstable electrical characteristics. The impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, and the like.

[0124] The metal oxide film 308c is an oxide film formed simultaneously with the oxide semiconductor films 308a and 308b. Therefore, the metal oxide film 308c is formed by processing an oxide semiconductor film. The oxide semiconductor film 308a contains the same metal element as the oxide semiconductor film 308b. , 308b, or a film having a different crystal structure. The oxide semiconductor film formed at the same time as the oxide semiconductor films 308a and 308b is doped with impurities or By providing oxygen deficiency, the film becomes conductive and functions as an electrode of a capacitor element. The impurity contained in the oxide semiconductor film is hydrogen. As, boron, phosphorus, tin, antimony, rare gas elements, alkali metals, alkaline earth metals Alternatively, the metal oxide film 308c may contain a metal or the like. , 308b is a film formed at the same time, and oxygen vacancies are formed due to plasma damage, etc. Alternatively, the metal oxide film 308c is a film having enhanced conductivity. It is a film formed at the same time as 8a and 308b, and contains impurities and is a plasma damage The film has oxygen vacancies due to oxidation and the like, and has increased conductivity.

[0125] Therefore, the oxide semiconductor films 308a and 308b and the metal oxide film 308c are insulating. The oxide semiconductor film 308a is formed over the oxide semiconductor film 306 but has a different impurity concentration. The impurity concentration of the metal oxide film 308c is higher than that of the oxide semiconductor film 308b. The hydrogen concentration in the membranes 308a and 308b is 5×10 19 atoms / cm 3less than, Preferably 1 x 10 19 atoms / cm 3 Less than or equal to 5 x 10 18 atoms / cm 3 Less than 1 × 10 18 atoms / cm 3 Less than or equal to 5 x 10 17 atoms / cm 3 Less than 1 × 10 16 atoms / cm 3 is less than or equal to metal The hydrogen concentration in the oxide film 308c is 8×10 19 atoms / cm 3 Above, preferably is 1 x 10 20 atoms / cm 3 More preferably, 5 × 10 20 atoms / cm 3 In addition, compared with the oxide semiconductor films 308a and 308b, the metal oxide film 30 The hydrogen concentration in 8c is twice as high, preferably 10 times or more.

[0126] In addition, the oxide semiconductor film formed at the same time as the oxide semiconductor films 308a and 308b is treated with a plasma. The oxide semiconductor film can be damaged by exposure to ultraviolet light, and oxygen vacancies can be formed. For example, a film is formed on an oxide semiconductor film by plasma CVD or sputtering. As a result, the oxide semiconductor film is exposed to the plasma, and oxygen vacancies are generated. The oxide semiconductor film is exposed to plasma during etching to form the oxide semiconductor film 12. Alternatively, when the oxide semiconductor film is exposed to hydrogen, a rare gas, ammonia, or an acid, oxygen vacancies are generated. When exposed to a plasma of a gas mixture of oxygen and hydrogen, oxygen vacancies are generated. The oxide semiconductor film becomes conductive, and the metal oxide film 308c It functions as:

[0127] In other words, the metal oxide film 308c can be said to be formed of an oxide semiconductor film with high conductivity. It can also be said that the metal oxide film 308c is formed of a metal oxide film with high conductivity.

[0128] When a silicon nitride film is used as the insulating film 314, the silicon nitride film contains hydrogen. Therefore, hydrogen in the insulating film 314 is formed simultaneously with the oxide semiconductor films 308a and 308b. When hydrogen diffuses into the oxide semiconductor film, hydrogen bonds with oxygen in the oxide semiconductor film and In addition, silicon nitride films are formed by plasma CVD or sputtering. When the oxide semiconductor film is formed by the ring method, the oxide semiconductor film is exposed to plasma, and oxygen vacancies are generated. When hydrogen contained in the silicon nitride film enters the oxygen vacancy, electrons, which are carriers, are generated. As a result, the conductivity of the oxide semiconductor film becomes high and the oxide semiconductor film becomes a metal oxide film 308c. do.

[0129] When hydrogen is added to an oxide semiconductor with oxygen vacancies, hydrogen enters the oxygen vacancy sites. A donor level is formed near the conduction band. As a result, the oxide semiconductor has high conductivity. The oxide semiconductor that has been made conductive can be called an oxide conductor. The metal oxide film 308c can be said to be formed using an oxide conductor film. Semiconductors have a large energy gap and are therefore transparent to visible light. An oxide conductor is an oxide semiconductor having a donor level near the conduction band. The influence of absorption due to the core level is small, and the transparency to visible light is comparable to that of oxide semiconductors. do.

[0130] The metal oxide film 308c has a lower resistivity than the oxide semiconductor films 308a and 308b. The resistivity of the oxide film 308c is 1×10 - 8 1×10 times more -1 It is preferably less than 1×10 -3 Ωcm or more 1×10 4 Ωcm, and more preferably a resistivity of 1×10 -3 Ωcm or more 1×10 - 1 It is preferable that the resistivity is less than Ωcm.

[0131] However, one aspect of the embodiment of the present invention is not limited to this, and the metal oxide film 308c is In some cases, it is possible that the insulating film 314 is not in contact with the insulating film 314 .

[0132] Furthermore, one aspect of the embodiment of the present invention is not limited to this, and the metal oxide film 308c may be In some cases, the oxide semiconductor film 308a and the oxide semiconductor film 308b may be formed in separate steps. In that case, the metal oxide film 308c is preferably formed by mixing the oxide semiconductor films 308a and 308b with the oxide semiconductor films 308a and 308b. For example, the metal oxide film 308c may be made of ITO or ITO. It may be formed using indium zinc oxide or the like.

[0133] In the liquid crystal display device described in this embodiment, the capacitor element has a light-transmitting property. The aperture ratio of the pixel can be increased while increasing the area occupied by the pixel.

[0134] The conductive films 310a, 310b, 310c, 310d, and 310e are made of aluminum as a conductive material. Aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, Silver, tantalum, or tungsten, or an alloy with this as its main component. It is used as a single layer structure or a laminated structure. For example, a single layer structure of an aluminum film containing silicon is used. Two-layer structure with titanium film laminated on aluminum film, and titanium film laminated on tungsten film a two-layer structure in which a copper film is laminated on a copper-magnesium-aluminum alloy film; A titanium film or a titanium nitride film and an aluminum film overlaid on the titanium film or the titanium nitride film. A three-layer structure in which a titanium film or titanium nitride film is formed on top of a titanium or copper film. Molybdenum film or molybdenum nitride film and the molybdenum film or molybdenum nitride film An aluminum film or copper film is layered on top, and a molybdenum film or nitride film is then layered on top of that. There are three-layer structures that form a molybdenum film. A transparent conductive material containing lead may also be used.

[0135] The insulating film 306, the oxide semiconductor films 308a and 308b, the metal oxide film 308c, and the conductive film On the films 310a, 310b, 310c, 310d, and 310e, the inorganic insulating film 53 is formed. An insulating film 312 and an insulating film 314 are formed. The insulating film 312 is formed in the same manner as the insulating film 306. In addition, it is preferable to use a material that can improve the interface characteristics with the oxide semiconductor film. Here, the insulating film 312 can be formed using an insulating oxide insulating film. The films 312a and 312b are formed by laminating them.

[0136] The insulating film 312a is an oxide insulating film that transmits oxygen. When the insulating film 312b is formed on the oxide semiconductor films 308a and 308b, the insulating film 312b is formed on the oxide semiconductor films 308a and 308b. It also functions as a film for reducing damage to the metal oxide film 308c.

[0137] The insulating film 312a has a thickness of 5 nm to 150 nm, preferably 5 nm to 500 nm. A silicon oxide film, a silicon oxynitride film, or the like having a thickness of 0 nm or less can be used. In the specification, a silicon oxynitride film is a film having a higher oxygen content than nitrogen content. A silicon nitride oxide film is a film that contains more nitrogen than oxygen. It refers to a thin membrane.

[0138] The insulating film 312a is an oxide insulating film containing nitrogen. It is preferable that the amount of defects is small.

[0139] A typical example of an oxide insulating film containing nitrogen and having few defects is a silicon oxynitride film. , aluminum oxide nitride film, etc.

[0140] The oxide insulating film containing nitrogen and having few defects can be measured at ESR below 100K. The first signal in the obtained spectrum has a g-value between 2.037 and 2.039. The second signal has a g value between 2.001 and 2.003, and a g value between 1.964 and 1.96 A third signal of 6 or less is observed. The split width of the second and third signals is approximately 5 m in X-band measurements. T. The first signal has a g value of 2.037 or more and 2.039 or less, and the second signal has a g value of 2.0 A second signal between 01 and 2.003, and a g value between 1.964 and 1.966, The total spin density of a third signal is 1×10 18 spins / cm 3 Less than Typically, it is 1×10 17 spins / cm 3 More than 1×1018 spins / cm 3 Not yet It is full.

[0141] In addition, the g value is between 2.037 and 2.039 in the ESR spectrum below 100K. The first signal has a g value of 2.001 or more and 2.003 or less, and the second signal has a g value of 1 The third signal, between 0.964 and 1.966, is nitrogen oxide (NO x , x is between 0 and 2 Representative examples of nitrogen oxides include: , nitrogen monoxide, nitrogen dioxide, etc. That is, the first a signal with a g value between 2.001 and 2.003, and a second signal with a g value between 1.9 The smaller the sum of the spin densities of the third signals, which is between 64 and 1.966, the higher the oxidation It can be said that the content of nitrogen oxides contained in the insulating film is small.

[0142] If the insulating film 312a has a low content of nitrogen oxides as described above, the insulating film 312a and It is possible to reduce carrier traps at the interface with the oxide semiconductor film. As a result, it is possible to reduce the amount of fluctuation in the threshold voltage of the transistor included in the semiconductor device. This makes it possible to reduce fluctuations in the electrical characteristics of the transistor.

[0143] The insulating film 312a is formed by SIMS (Secondary Ion Mass Spectroscopy). The nitrogen concentration measured by CT is 6×10 20 atoms / cm 3 Below is As a result, nitrogen oxides are less likely to be generated in the insulating film 312a. Therefore, the carriers at the interface between the insulating film 312a and the oxide semiconductor films 308a and 308b are It is possible to reduce traps. It is possible to reduce the shift in the low voltage, and to reduce the fluctuation in the electrical characteristics of the transistor. It is possible.

[0144] If the insulating film 312a contains nitrogen oxides and ammonia, During the heat treatment process, nitrogen oxides and ammonia react to form nitrogen oxides. As a result, the nitrogen concentration and the nitrogen oxide concentration in the insulating film 312a decrease. In addition, the insulating film 312a, the oxide semiconductor film 308a, and the oxide semiconductor film 308b can be reduced. It is possible to reduce the trapping of carriers at the interface with 308b. It is possible to reduce the shift in the threshold voltage of the transistor included in the semiconductor device, Fluctuations in the electrical characteristics of the transistor can be reduced.

[0145] In the insulating film 312a, all of the oxygen that has entered the insulating film 312a from the outside is absorbed by the insulating film 312a. Some oxygen does not move to the outside of the insulating film 312a and remains in the insulating film 312a. As oxygen enters the insulating film 312a, oxygen contained in the insulating film 312a moves out of the insulating film 312a. This may cause oxygen to move in the insulating film 312a.

[0146] When an oxide insulating film that transmits oxygen is formed as the insulating film 312a, The insulating film 312a is formed on the oxide semiconductor layer 311. ... It can be transferred to the membranes 308a, 308b.

[0147] An insulating film 312b is formed so as to be in contact with the insulating film 312a. The oxide insulating film is formed using an oxide insulating film containing more oxygen than the oxygen required for the stoichiometric composition. An oxide insulating film containing more oxygen than that satisfying the stoichiometric composition loses some of the oxygen by heating. The oxide insulating film containing more oxygen than the stoichiometric composition has a T In DS analysis, the amount of oxygen desorbed, converted to oxygen atoms, was 1.0 x 10 18 atoms / cm 3 or more, preferably 3.0 × 10 20 atoms / cm 3 The oxide insulating film is The surface temperature of the film during the TDS analysis was 100°C or higher and 700°C or lower. The temperature is preferably in the range of 100°C or higher and 500°C or lower.

[0148] The insulating film 312b has a thickness of 30 nm to 500 nm, preferably 50 nm or more. Silicon oxide, silicon oxynitride, etc., up to 400 nm or less can be used.

[0149] Furthermore, it is preferable that the insulating film 312b has a small number of defects. Therefore, the spin density of the signal appearing at g=2.001, which is due to the dangling bond of silicon, Degrees are 1.5 x 10 18 spins / cm 3 Less than or even 1×10 18 spins / cm 3 The insulating film 312b is preferably an oxide film or less than the insulating film 312a. Since it is separated from the semiconductor films 308a and 308b, the defect density is higher than that of the insulating film 312a. This is also good.

[0150] The insulating film 314 is made of a blocker such as oxygen, hydrogen, water, alkali metal, alkaline earth metal, etc. By providing a nitride insulating film having a blocking effect, the oxide semiconductor films 308a, 308b, and The nitride insulating film and the metal oxide film 308c can prevent oxygen from diffusing to the outside. Examples include silicon nitride film, silicon nitride oxide film, aluminum nitride film, and aluminum nitride oxide film. Examples include um membranes.

[0151] In addition, the material has a blocking effect against oxygen, hydrogen, water, alkali metals, alkaline earth metals, etc. An oxide insulating film having a blocking effect against oxygen, hydrogen, water, etc. is provided over the nitride insulating film. As the oxide insulating film having a blocking effect against oxygen, hydrogen, water, and the like, an oxide insulating film may be used. Aluminum, aluminum oxide nitride, gallium oxide, gallium oxide nitride, yttrium oxide Examples include yttrium oxide nitride, hafnium oxide, and hafnium oxide nitride. In order to control the capacitance value of the element, oxygen, hydrogen, water, alkali metals, alkaline earth metals, etc. A nitride insulating film or an oxide insulating film may be appropriately provided on the nitride insulating film having a locking effect. good.

[0152] The conductive film 316b is formed over the insulating film 314 and can function as an electrode of a capacitor. can.

[0153] The conductive film 316b can be formed using a light-transmitting conductive material. Examples of the conductive material having light-transmitting properties include indium oxide containing tungsten oxide, tungsten oxide, and Indium zinc oxide containing tungsten, indium oxide containing titanium oxide, titanium oxide Indium tin oxide containing silicon, ITO, indium zinc oxide, indium with silicon oxide Examples include indium tin oxide.

[0154] The organic insulating film 317 is made of organic resin such as acrylic resin, polyimide, or epoxy resin. The organic insulating film 317 may have a thickness of 500 nm or more and 5000 nm or less. The thickness of the organic insulating film 317 is preferably 1000 nm or more and 3000 nm or less. By doing so, it is possible to fill the recesses on the conductive film 316b with the organic insulating film 317. As a result, the unevenness of the region where the alignment film 320 is formed can be reduced.

[0155] By forming the organic insulating film 317 using an organic resin, it is possible to form a film that functions at least as a pixel electrode. The recessed portion of the conductive film 316b can be filled with the organic insulating film 317, and the liquid crystal layer 32 It is possible to reduce the alignment irregularities of the liquid crystal material that constitutes 1.

[0156] Conductive films 319 and 319a are formed on the organic insulating film 317. The conductive film 319a functions as a pixel electrode. ) and electrically connected to the conductive film 310a, and the opening 364b (see FIG. 9(A)) That is, the conductive film 304a and the conductive film 310c are electrically connected to each other. It functions as a connecting electrode for connecting c.

[0157] The organic insulating film 317 is not limited to this. For example, the organic insulating film 317 may be a color filter. It is also possible to provide the function of a filter or a black matrix. When 17 has a function of a color filter, for example, red pixels, blue pixels, green The organic insulating film 317 having color properties may be formed for each color in accordance with the color pixels.

[0158] The conductive films 319 and 319a are formed using a light-transmitting conductive material similar to the conductive film 316b. It can be formed by

[0159] In order to form a connection structure in which the conductive film 304a and the conductive film 310c are in direct contact with each other, Before forming the conductive film 310c, a pattern is formed in order to form openings in the insulating films 305 and 306. However, as shown in Figure 4, the conductive film The conductive film 304a and the conductive film 310c are connected by the conductive film 319a. In addition, it is no longer necessary to form a connection portion where the conductive film 310c is in direct contact, and only one photomask is required. That is, the number of steps for manufacturing a liquid crystal display device can be reduced.

[0160] The alignment film 320 is preferably light-transmitting, and is typically made of acrylic resin, Organic resins such as polyimide and epoxy resins can be used.

[0161] Moreover, a colored film (hereinafter referred to as a colored film 346) is formed on the substrate 342. The colored film 346 functions as a color filter. A light-shielding film 344 is formed on the substrate 342 adjacent to the black matrix. The colored film 346 does not necessarily have to be provided. In the case where the display device is a black and white display device, the colored film 346 may not be provided.

[0162] The colored film 346 may be a colored film that transmits light in a specific wavelength band. For example, A red (R) film transmits light in the red wavelength band, and a green (G) film transmits light in the green wavelength band. ) film, a blue (B) film that transmits light in the blue wavelength band, or the like can be used.

[0163] The light-shielding film 344 may be made of metal, as long as it has the function of blocking light in a specific wavelength range. A film or an organic insulating film containing a black pigment or the like can be used.

[0164] An insulating film 348 is formed on the colored film 346. The insulating film 348 is formed by a planarizing method. The function of the colored film 346 is to prevent impurities contained therein from diffusing toward the liquid crystal element. It has the function of controlling

[0165] In addition, a conductive film 350 is formed on the insulating film 348. The conductive film 350 is The conductive film 319 and the conductive film 311 function as the other of the pair of electrodes of the liquid crystal element. An alignment film 352 is formed on the liquid crystal display panel 9 a and the conductive film 350 .

[0166] In addition, a liquid crystal layer 321 is formed between the conductive films 319, 319a and the conductive film 350. The liquid crystal layer 321 is bonded to the substrate 302 and the substrate 342 using a sealing material (not shown). The seal is made of a material that prevents moisture from entering from the outside. In particular, a configuration in which the inorganic material is in contact with the inorganic material is preferred.

[0167] In addition, the thickness of the liquid crystal layer 321 (cell gap) is set between the conductive films 319, 319a and the conductive film 350. A spacer may be provided to maintain the gap (also called a gap).

[0168] Regarding a method for manufacturing an element portion provided on a substrate 302 shown in the liquid crystal display device shown in FIG. 5 to 8. Here, the element portion provided on the substrate 302 is In this case, it refers to the region sandwiched between the substrate 302 and the alignment film 320 .

[0169] The films constituting the transistor (insulating film, oxide semiconductor film, metal oxide film, conductive film, etc.) Sputtering, chemical vapor deposition (CVD), vacuum evaporation, pulsed laser deposition (PL Alternatively, it can be formed by a coating method or a printing method. The film formation methods are sputtering and plasma enhanced chemical vapor deposition (PECVD). Although typical, thermal CVD may also be used. An example of a thermal CVD method is MOCVD (metal organic chemical vapor deposition). Vapor phase deposition (CVD) or atomic layer deposition (ALD) may also be used.

[0170] In the thermal CVD method, the pressure in the chamber is atmospheric or reduced, and the source gas and oxidant are simultaneously mixed. The reaction is carried out in the chamber near or on the substrate, where it is deposited on the substrate to form a film. As described above, the thermal CVD method is a film formation method that does not generate plasma. This has the advantage that defects are not generated due to damage.

[0171] In addition, in the ALD method, the pressure inside the chamber is atmospheric or reduced, and the source gas for the reaction is The gases are introduced into the chamber in sequence, and the film is formed by repeating this gas introduction sequence. By switching between the switching valves (also called high-speed valves), two or more types of raw materials can be mixed. The gases are supplied to the chamber in order, and the first source gas is supplied to the chamber in order to prevent the mixture of the source gases. At the same time as or after the second gas, an inert gas (argon, nitrogen, etc.) is introduced. If an inert gas is introduced at the same time, the inert gas acts as a carrier gas. In addition, an inert gas may be introduced at the same time as the second source gas is introduced. In addition, instead of introducing an inert gas, the first source gas is discharged by vacuum evacuation, and then the second source gas is introduced. The first source gas may be introduced. The first source gas is adsorbed on the surface of the substrate to form a first layer. The second layer is deposited on the first layer by reacting with the second source gas introduced later, forming a thin film. is formed.

[0172] This gas introduction sequence is controlled and repeated multiple times until the desired thickness is achieved. The thickness of the thin film increases depending on the number of times the gas introduction sequence is repeated. Therefore, precise film thickness control is possible, and fine transistors can be fabricated. It is suitable for manufacturing.

[0173] First, prepare a substrate 302. Here, a glass substrate is used as the substrate 302.

[0174] Next, a conductive film is formed on the substrate 302 and processed into a desired shape. The conductive films 304a, 304b, and 304c are formed. c) forming a mask by first patterning into a desired shape, and This can be achieved by etching away the unfilled areas (see Figure 5(A)).

[0175] The conductive films 304a, 304b, and 304c are typically formed by sputtering. It can be formed by using vacuum deposition, pulsed laser deposition (PLD), thermal CVD, etc. can.

[0176] Conductive films 304a, 304b, and 304c are formed by a film forming apparatus using ALD. In this case, WF6 gas and B2H6 gas are sequentially supplied. Repeatedly introduce WF6 gas and H2 gas to form an initial tungsten film. The tungsten film is formed by introducing SiH4 gas instead of B2H6 gas. Good too.

[0177] Next, an insulating film 305 is formed on the substrate 302 and the conductive films 304a, 304b, and 304c. Then, an insulating film 306 is formed on the insulating film 305 (see FIG. 5(A)).

[0178] The insulating film 305 and the insulating film 306 are formed by a method such as a sputtering method, a CVD method, a vacuum deposition method, or a PLD method. The insulating film 305 and the insulating film 306 can be formed by a method such as a thermal CVD method. It is preferable to form the layers continuously in a vacuum, since this prevents the inclusion of impurities.

[0179] A silicon oxide film or a silicon oxynitride film is formed as the insulating film 305 and the insulating film 306. In this case, a deposition gas containing silicon and an oxidizing gas can be used as the source gas. Representative examples of silicon-containing deposition gases include silane, disilane, and trisilane. , fluorinated silane, etc. Oxidizing gases include oxygen, ozone, nitrous oxide, and nitrogen dioxide. There are elements such as

[0180] When a gallium oxide film is formed as the insulating film 305 and the insulating film 306, MOCV It can be formed using Method D.

[0181] The insulating film 305 and the insulating film 306 are formed by using a film forming apparatus that uses ALD. When forming a hafnium chloride film, a solvent and a liquid containing a hafnium precursor compound (hafnium Hafnium alkoxide solution, typically tetrakisdimethylamidohafnium (TDMAH) Two types of gases are used: the source gas, which is vaporized ozone (O3), as an oxidizing agent. The chemical formula for tetrakisdimethylamidohafnium is Hf[N(CH3)2]4. Other liquid materials include tetrakis(ethylmethylamido)hafnium.

[0182] The insulating film 305 and the insulating film 306 are formed by using a film forming apparatus that uses ALD. When forming an aluminum chloride film, a liquid (aluminum precursor compound) containing a solvent and an aluminum precursor compound is used. The raw material gas is vaporized trimethylaluminum (TMA) and H2O as an oxidizer. Two types of gases are used. The chemical formula of trimethylaluminum is Al(CH3)3. Other liquid materials include tris(dimethylamido)aluminum and triisobutyl aluminum tris(2,2,6,6-tetramethyl-3,5-hepta) and d'ionato).

[0183] The insulating film 305 and the insulating film 306 are formed by using a film forming apparatus that uses ALD. When forming a silicon dioxide film, hexadichlorodisilane is adsorbed onto the surface to be formed. It removes chlorine from the substance and supplies radicals of oxidizing gases (O2, nitrous oxide) for absorption. React with the kimono.

[0184] Next, an oxide semiconductor film 307 is formed over the insulating film 306 (see FIG. 5B).

[0185] The oxide semiconductor film 307 can be formed by a sputtering method, a coating method, a pulsed laser deposition method, a laser The film can be formed by ablation, thermal CVD, or the like.

[0186] The sputtering gas is a rare gas (typically argon), oxygen gas, or a rare gas and oxygen gas. In the case of a mixed gas of rare gas and oxygen, the amount of oxygen relative to the rare gas is It is preferable to increase the ratio of the nitrogen gas.

[0187] The target may be appropriately selected depending on the composition of the oxide semiconductor film to be formed. .

[0188] Note that when the oxide semiconductor film is formed by, for example, a sputtering method, The temperature is 150°C or higher and 750°C or lower, preferably 150°C or higher and 450°C or lower, and more preferably The oxide semiconductor film is formed at a temperature of 200°C or higher and 350°C or lower. S film can be formed.

[0189] In addition, the following conditions are preferably applied to form the CAAC-OS film.

[0190] By suppressing the inclusion of impurities during film formation, it is possible to prevent the crystal state from being destroyed by impurities. For example, the concentration of impurities (hydrogen, water, carbon dioxide, nitrogen, etc.) present in the film formation chamber can be In addition, the impurity concentration in the deposition gas can be reduced. A deposition gas at a temperature of -80°C or less, preferably -100°C or less, is used.

[0191] The film formation equipment using ALD is used to form oxide semiconductor films, such as In-Ga-Zn-O films. When forming an InO layer, In(CH3)3 gas and O3 gas are introduced repeatedly in sequence. Then, Ga(CH3)3 gas and O3 gas are introduced simultaneously to form a GaO layer. Then, Zn(CH3)2 gas and O3 gas are introduced simultaneously to form a ZnO layer. The order of these layers is not limited to this example. In addition, by mixing these gases, an In-Ga-O layer or A mixed compound layer such as an In-Zn-O layer or a Ga-Zn-O layer may also be formed. Instead of the gas, H2O gas bubbled with an inert gas such as Ar may be used. It is preferable to use O3 gas, which does not contain In(CH3)3 gas. 2H5)3 gas may be used. Also, instead of Ga(CH3)3 gas, Ga(C2H5 In(CH3)3 gas may be used instead of In(C2H5)3 gas. Alternatively, Zn(CH3)2 gas may be used.

[0192] Next, the oxide semiconductor film 307 is processed into a desired shape to form an island-shaped oxide semiconductor film 3 The oxide semiconductor films 308a, 308b, and 308d are formed. In step 08d, a mask is formed by second patterning in a desired shape, and the mask is then covered with the mask. The etching can be performed by etching the unetched area. Dry etching, wet etching, or a combination of both can be used. This can be done (see FIG. 5(C)).

[0193] After that, heat treatment is performed to remove the oxide semiconductor films 308a, 308b, and 308d. The hydrogen, water, and the like contained in the oxide semiconductor films 308a, 308b, and 308d are released. The hydrogen concentration and the water concentration may be reduced. As a result, the highly purified oxide semiconductor film 308 The temperature of the heat treatment is typically 2 The temperature is set to 50°C or higher and 650°C or lower, preferably 300°C or higher and 500°C or lower. The treatment temperature is typically 300°C or higher and 400°C or lower, preferably 320°C or higher and 370°C or lower. By doing the following, it is possible to reduce warpage and shrinkage of the substrate even in large area substrates. and the yield is improved.

[0194] The heat treatment can be performed using an electric furnace, an RTA device, or the like. Therefore, the heat treatment can be performed at a temperature above the distortion point of the substrate for a short period of time. It is possible to shorten the heat treatment time and reduce the warping of the substrate during the heat treatment. This is particularly preferable for large-area substrates.

[0195] The heat treatment is carried out in an atmosphere of nitrogen, oxygen, or ultra-dry air (water content of 20 ppm or less, preferably air at 1 ppm or less, preferably 10 ppb or less), or rare gases (argon, helium The above-mentioned nitrogen, oxygen, ultra-dry air, or rare gas may be added to the atmosphere of water. It is preferable that the material does not contain nitrogen, water, etc. Furthermore, after heat treatment in a nitrogen or rare gas atmosphere, Alternatively, the oxide semiconductor film may be heated in an oxygen or ultra-dry air atmosphere. Hydrogen, water, and the like can be released from the oxide semiconductor film, and oxygen can be supplied to the oxide semiconductor film. As a result, the amount of oxygen vacancies in the oxide semiconductor film can be reduced.

[0196] In addition, when the film formation temperature of the insulating film 311a to be formed later is set to 280° C. or more and 400° C. or less, In this case, hydrogen, water, and the like contained in the oxide semiconductor films 308a, 308b, and 308d are released. Therefore, the heat treatment is not necessary.

[0197] Next, a conductive film 3 is formed over the insulating film 306 and the oxide semiconductor films 308a, 308b, and 308d. 09 (see Figure 6(A)).

[0198] The conductive film 309 is formed by sputtering, vacuum deposition, PLD, thermal CVD, or the like. It can be formed by

[0199] Next, the conductive film 309 is processed into a desired shape, thereby forming conductive films 310a, 310b, and 311. The conductive films 310a, 310b, 310c, 310d, and 310e are formed. 10d and 310e are steps for forming a mask by third patterning in a desired shape, and then the mask is It can be formed by etching the area not covered by the mask (Figure 6(B)). reference.).

[0200] Next, the insulating film 306, the oxide semiconductor films 308a, 308b, and 308d, and the conductive film 31 Insulating films 311a and 311b are formed on the insulating films 310a, 310b, 310c, 310d, and 310e. 1b are laminated to form an insulating film 311 (see FIG. 6(C)). It can be formed by using a tartering method, a CVD method, a vapor deposition method, or the like.

[0201] After the insulating film 311a is formed, the insulating film 311b is successively formed without being exposed to the atmosphere. After the insulating film 311a is formed, the flow rate of the source gas is preferably adjusted without exposing the insulating film 311a to the atmosphere. The insulating film 311b is continuously formed by adjusting one or more of the pressure, the high frequency power, and the substrate temperature. This reduces the concentration of impurities originating from atmospheric components at the interface between the insulating films 311a and 311b. In addition, oxygen contained in the insulating film 311b can be removed by the oxide semiconductor films 308a and 308b. The oxide semiconductor films 308a, 308b, and 308d can be transferred to the oxide semiconductor films 308a, 308b, and 308d. The amount of oxygen vacancy in 08d can be reduced.

[0202] For the insulating film 311a, the oxidizing gas is more than 20 times and 100 times the deposition gas. The pressure in the processing chamber is set to less than 100 Pa, preferably 40 to 80. By using the CVD method at 50 Pa or less, it is possible to obtain an oxide insulating film containing nitrogen and with few defects. A velum can be formed.

[0203] As the source gas for the insulating film 311a, a deposition gas containing silicon and an oxidizing gas are used. Representative examples of silicon-containing deposition gases include silane, disilane, and thiazol-2-ylsilane. Examples of oxidizing gases include oxygen, ozone, nitrous oxide, Examples include nitrogen dioxide.

[0204] By using the above conditions, an oxide insulating film that transmits oxygen is formed as the insulating film 311a. Furthermore, by providing the insulating film 311a, the insulating film 311b to be formed later can be formed. In the formation process, damage to the oxide semiconductor films 308a, 308b, and 308d can be reduced. It is Noh.

[0205] The insulating film 311b is made of a silicon dioxide film placed in a vacuum-evacuated processing chamber of a plasma CVD apparatus. The substrate is maintained at 180°C or higher and 280°C or lower, more preferably 200°C or higher and 240°C or lower. A raw material gas is introduced into the processing chamber to set the pressure in the processing chamber at 100 Pa or more and 250 Pa or less. More preferably, the pressure should be between 100 Pa and 200 Pa, and the pressure should be 0. 17W / cm 2 More than 0.5W / cm 2 or less, more preferably 0.25 W / cm 2 Over 0 .35W / cm 2 Silicon oxide film or oxynitride film is formed by supplying the following high frequency power. A silicon dioxide film is formed.

[0206] As the source gas for the insulating film 311b, a deposition gas containing silicon and an oxidizing gas are used. Representative examples of silicon-containing deposition gases include silane, disilane, and thiazol-2-ylsilane. Examples of oxidizing gases include oxygen, ozone, nitrous oxide, Examples include nitrogen dioxide.

[0207] The insulating film 311b is formed under the conditions of high frequency irradiation at the above power density in a processing chamber under the above pressure. Supplying power increases the efficiency of decomposition of the source gas in the plasma, increasing the number of oxygen radicals. However, as the oxidation of the source gas progresses, the oxygen content in the insulating film 311b becomes lower than the stoichiometric composition. However, if the substrate temperature is the temperature at which the insulating film 311b is formed, Because the bond between silicon and oxygen is weak, some of the oxygen is released when heated. Oxidation that contains more oxygen than the stoichiometric composition and in which some of the oxygen is released by heating In addition, oxide semiconductor films 308a, 308b, and 308d can be formed. Therefore, in the process of forming the insulating film 311b, The insulating film 311a serves as a protective film for the oxide semiconductor films 308a, 308b, and 308d. As a result, damage to the oxide semiconductor films 308a, 308b, and 308d can be reduced while achieving high power. The insulating film 311b can be formed using low-density high-frequency power.

[0208] In the film formation conditions for the insulating film 311b, the deposition property containing silicon in the oxidizing gas is By increasing the flow rate of the gas, it is possible to reduce the number of defects in the insulating film 311b. Specifically, ESR measurements reveal that g=2.001 originates from silicon dangling bonds. The spin density of the signal appearing in 17 spins / cm 3 Less than 3 x 10 17 spins / cm 3 Less than or equal to 1.5 × 10 17 spins / cm 3 Below is As a result, an oxide insulating film containing nitrogen and having a small number of defects can be formed. This can improve the reliability of the transistor.

[0209] Next, a heat treatment is carried out. The temperature of the heat treatment is typically 150° C. or higher but not higher than the substrate distortion point. Preferably, the temperature is 200°C or higher and 450°C or lower, and more preferably, 300°C or higher and 450°C or lower. The temperature of the heat treatment is typically 300° C. or higher and 400° C. or lower, preferably By keeping the temperature between 320℃ and 370℃, warping and shrinkage of the substrate can be prevented even in large area substrates. It is possible to reduce the amount of lead, thereby improving the yield.

[0210] The heat treatment can be carried out using an electric furnace, an RTA device, or the like. Therefore, heat treatment can be performed at a temperature above the strain point of the substrate for a short period of time. The processing time can be reduced.

[0211] Heat treatment is carried out in a nitrogen, oxygen, or ultra-dry air (water content of 20 ppm or less, preferably 1 ppm). pm or less, preferably 10 ppb or less air), or rare gases (argon, helium, etc.) The above-mentioned nitrogen, oxygen, ultra-dry air, or rare gas may be mixed with hydrogen, water, or the like. It is preferable that the above is not included.

[0212] By this heat treatment, part of oxygen contained in the insulating film 311b is oxidized to the oxide semiconductor film 308a , 308b, and 308d, and the oxide semiconductor films 308a, 308b, and 308d are formed by the transfer of the oxide semiconductor film 308a, 308b, and 308d. As a result, the amount of oxygen vacancies can be reduced. The amount of oxygen vacancies contained in 8b and 308d can be further reduced.

[0213] In addition, when the insulating films 311a and 312b contain water, hydrogen, etc., the insulating films 311a and 312b are used to block the water, hydrogen, etc. An insulating film 313 having a function of blocking is formed later, and then heat treatment is performed to form the insulating film 311a. Water, hydrogen, and the like contained in the oxide semiconductor film 311b move to the oxide semiconductor films 308a, 308b, and 308d. However, defects occur in the oxide semiconductor films 308a, 308b, and 308d. By this heating, water, hydrogen, etc. contained in the insulating films 311a and 311b can be desorbed. This reduces variations in the electrical characteristics of the transistors and also reduces variations in the threshold voltage. can be suppressed.

[0214] In addition, by forming the insulating film 311b on the insulating film 311a while heating, an oxide semiconductor Oxygen is transferred to the oxide semiconductor films 308a, 308b, and 308d. b, 308d, it is possible to reduce the amount of oxygen vacancies contained in the It is not necessary.

[0215] In addition, when the conductive films 310a, 310b, 310c, 310d, and 310e are formed, The oxide semiconductor films 308a, 308b, and 308d are damaged by the etching of the film. The back channels (oxide semiconductor films 308a and 308b) of the oxide semiconductor films 308a and 308b are In 08b, the surface opposite to the conductive films 304a and 304c which function as gate electrodes is However, oxygen vacancies occur on the other side of the insulating film 311b. By using an oxide insulating film containing more oxygen than silicon, the back The oxygen vacancies occurring on the channel side can be repaired. The defects contained in 308a and 308b can be reduced, improving the reliability of the transistor. It can be raised.

[0216] Note that the heat treatment may be performed after the opening 362, which will be formed later, is formed.

[0217] Next, the insulating film 311 is processed into a desired shape to form an insulating film 312 and an opening 362. The insulating film 312 and the opening 362 are formed in a desired shape by a fourth patterning. By forming a mask using etching and etching the area not covered by the mask, It is possible to form (see FIG. 7(A)).

[0218] Note that the opening 362 is formed so that the surface of the oxide semiconductor film 308d is exposed. The opening 362 can be formed by dry etching, for example. It is preferable to etch the insulating film 311 by dry etching. The oxide semiconductor film 308d is exposed to plasma during the etching process. However, the amount of oxygen vacancies in the film 308d can be increased by the method of forming the opening 362. The etching method is not limited to this, and may be a wet etching method or a dry etching method. A formation method in combination with wet etching may also be used.

[0219] Next, the insulating film 313 is formed over the insulating film 312 and the oxide semiconductor film 308d (FIG. 7( See B). ).

[0220] The insulating film 313 is made of a material containing impurities from the outside, such as oxygen, hydrogen, water, alkali metals, It is preferable to use a material that prevents alkaline earth metals and the like from diffusing into the oxide semiconductor film. and preferably contains hydrogen, and typically contains nitrogen, such as nitride. The insulating film 313 can be formed by, for example, a CVD method or a sputtering method. The film can be formed by using a coating method.

[0221] When the insulating film 313 is formed by plasma CVD or sputtering, the oxide semiconductor The insulating film 313 is exposed to plasma, and oxygen vacancies are generated in the oxide semiconductor film. impurities from the outside, such as water, alkali metals, alkaline earth metals, etc., It is a membrane made of a material that prevents hydrogen from diffusing into the body membrane, and it also contains hydrogen. When hydrogen in the film 313 diffuses into the oxide semiconductor film 308d, In this case, hydrogen bonds with oxygen, generating electrons as carriers. When hydrogen enters the oxygen vacancies, electrons are generated as carriers. The oxide semiconductor film 308d has high conductivity and becomes the metal oxide film 308c.

[0222] In addition, the insulating film 313 is preferably formed at a high temperature in order to enhance blocking properties. For example, the substrate temperature is 100° C. or higher and 400° C. or lower, more preferably 300° C. or higher and 400° C. or lower. In addition, when the oxide semiconductor film is formed at a high temperature, it is preferable to form the oxide semiconductor film by heating at a temperature of 1000 K or more. Oxygen is released from the oxide semiconductors used as 308a and 308b, and the carrier concentration increases. Therefore, the temperature should be set at a level at which such a phenomenon does not occur.

[0223] Next, a conductive film 315 is formed over the insulating film 314 (see FIG. 8A).

[0224] The conductive film 315 can be formed by, for example, a sputtering method.

[0225] Next, the conductive film 315 is processed into a desired shape to form 316b. The film 316b is formed into a desired shape by a mask using a fifth patterning process. This can be achieved by etching the uncovered areas (see Figure 8(B)). .

[0226] Next, an organic insulating film 317 is formed so as to cover the insulating film 314 and the conductive film 316b (FIG. 8 The organic insulating film 317, which functions as a planarizing film, is formed on the insulating film 313 and the conductive film 314. Each of the electrodes 316b has an opening so that a portion of the electrode 316b is exposed.

[0227] The organic insulating film 317 is formed by applying a coating method such as spin coating or dip coating. After applying a photosensitive composition onto the insulating film 313 and the conductive film 316b, a sixth photomask is applied. The composition is exposed and developed by the photolithography process used, and then subjected to a heat treatment. When a non-photosensitive composition is applied to the insulating film 313 and the conductive film 316b, A resist is applied onto the composition, and a photolithography process is performed using a sixth photomask. The resist is processed to form a mask, and the non-photosensitive composition is etched using the mask. By this, the organic insulating film 317 can be formed.

[0228] The organic insulating film 317 is formed by a wet method such as an ink jet method or a printing method. This allows the number of photomasks to be reduced.

[0229] Next, using the organic insulating film 317 as a mask, the insulating films 305, 306, and 312 are and the insulating film 313 are etched to form openings exposing the conductive film 304b. 364a, an opening 364b exposing the conductive film 310c, and an opening 364b exposing the conductive film 310e. 364c and an opening 364d that exposes the conductive film 316b are formed (see FIG. 9A). ).

[0230] Next, a conductive film 318 is formed (see FIG. 9B).

[0231] The conductive film 318 can be formed by, for example, a sputtering method.

[0232] Next, the conductive film 318 is processed into a desired shape to form conductive films 319 and 319a. The conductive films 319 and 319a are patterned in a desired shape by a mask using a seventh patterning method. The mask can be formed by etching the area not covered by the mask. (See FIG. 9(C)).

[0233] Through the above steps, a pixel portion having a transistor and a driver circuit portion are formed on the substrate 302. In the manufacturing process shown in this embodiment, the first to seventh patterns can be formed. This means that transistors and capacitors can be formed simultaneously using seven photomasks. can be done.

[0234] Note that in this embodiment, hydrogen contained in the insulating film 314 is diffused into the oxide semiconductor film 308d. The oxide semiconductor film 308d was dispersed to increase the conductivity. The oxide semiconductor film 308d is covered with a mask, and impurities, typically hydrogen, boron, or lithium, are introduced into the oxide semiconductor film 308d. Addition of tin, antimony, rare gas elements, alkali metals, alkaline earth metals, etc. The oxide semiconductor film 308d may be doped with hydrogen or boron to increase the conductivity. As a method for adding phosphorus, tin, antimony, rare gas elements, etc., there is an ion doping method. On the other hand, when an alkali metal or alkaline earth metal is added to the oxide semiconductor film 308d, As a method for adding metal or the like, a solution containing the impurity is applied to the oxide semiconductor film 308d. There is a way to do this.

[0235] Next, the element portion provided on the substrate 342 provided opposite the substrate 302 will be described below. Here, the element portion provided on the substrate 342 is and the alignment film 352.

[0236] First, a substrate 342 is prepared. The substrate 342 is made of the same material as the substrate 302. Next, a light-shielding film 344 and a colored film 346 are formed on the substrate 342 (FIG. 10( See A). ).

[0237] The light-shielding film 344 and the colored film 346 can be formed using various materials by a printing method, an ink-jet method, They are formed at desired positions by etching using photolithography technology.

[0238] Next, an insulating film 348 is formed on the light-shielding film 344 and the colored film 346 (see FIG. 10(B)). Light. ).

[0239] The insulating film 348 is made of an organic insulating material such as acrylic resin, epoxy resin, or polyimide. By forming the insulating film 348, for example, the colored film 34 6 can be prevented from diffusing impurities into the liquid crystal layer 321. However, the insulating film 348 is not necessarily provided, and a structure without the insulating film 348 may be used. Good too.

[0240] Next, a conductive film 350 is formed over the insulating film 348 (see FIG. 10C). The material for the conductive film 315 can be used as the conductive film 0.

[0241] Through the above steps, the structure formed on the substrate 342 can be formed.

[0242] Next, the insulating film 31 formed on the substrate 302 and the substrate 342, more specifically, on the substrate 302, 4, on the conductive films 319, 319a and the conductive film 350 formed on the substrate 342, respectively. The alignment film 320 and the alignment film 352 are formed by a rubbing method. The substrate 302 and the substrate 342 are then bonded to each other. The liquid crystal layer 321 is formed. The liquid crystal layer 321 is formed by a dispenser method (dropping method). Alternatively, the substrate 302 and the substrate 342 may be bonded together and then liquid crystal may be injected using capillary action. The entry method can be used.

[0243] Through the above steps, the liquid crystal display device shown in FIG. 4 can be manufactured.

[0244] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0245] (Embodiment 3) In this embodiment, a liquid crystal display device including a transistor different from that in Embodiment 1 will be described. This will be explained with reference to FIGS.

[0246] The liquid crystal display device shown in FIG. 11 has a dual gate structure in the driving circuit section indicated by AB. The semiconductor device is characterized by including a transistor 102a.

[0247] The transistor 102a provided in the driver circuit section is connected to a gate electrode provided on the substrate 302. The conductive film 304a functions as an electrode, and the insulating film 305 functions as a gate insulating film 51. 06, an oxide semiconductor film 308a formed over the insulating film 306, and an oxide semiconductor film 308 Conductive films 310a and 310b, which function as a source electrode and a drain electrode, are in contact with the conductive film 310a. In addition, an inorganic insulating film 5 is formed over the oxide semiconductor film 308a and the conductive films 310a and 310b. 3 is formed, and a conductive film 316d functioning as a gate electrode is formed on the inorganic insulating film 53. The conductive film 316d functioning as a gate electrode is formed between the gate insulating film 51 and the inorganic insulating film 53. In an opening (not shown) formed in the conductive film 304, which functions as a gate electrode, That is, the conductive film 304a and the conductive film 316a have the same potential.

[0248] Therefore, by applying the same voltage to each gate electrode of the transistor 102a, -Reduction of variations in characteristics, -Suppression of deterioration in GBT stress test and at different drain voltages In addition, the oxide semiconductor film 308 can suppress fluctuations in the on-state current rising voltage. In a, the area where the carriers flow is larger in the film thickness direction, so the carrier migration As a result, the on-current of the transistor 102a increases and the field effect As a result, the mobility is high, typically with a field-effect mobility of 20 cm 2 / V·s or more.

[0249] At the edge of the oxide semiconductor film processed by etching or the like, damage caused by the processing Defects are formed and the material is contaminated by impurities, so stresses such as electric fields When a potential is applied, it is easily activated, which makes it more likely to become n-type (low resistance). Therefore, the oxide semiconductor film 308a overlapping with the conductive film 304a functioning as a gate electrode The end portions are easily converted to n-type. The n-type end portions are connected to the source electrode and the drain electrode. When the conductive film 310a and the conductive film 310b are provided between the electrodes, the n-type region However, the channel width In the direction of the gate electrode, a conductive film 316d functioning as a gate electrode is provided. The side surface of the oxide semiconductor film 308a is affected by the electric field of the conductive film 316d functioning as an electrode. Alternatively, the occurrence of parasitic channels at the end portions including the side surfaces and their vicinity is suppressed. As a result, a transistor with excellent electrical characteristics is obtained, in which the drain current rises sharply at the threshold voltage. It becomes a star.

[0250] Note that the conductive film 316d functioning as a gate electrode is the same as the conductive film 316 The same materials as those in b can be used as appropriate.

[0251] <Variation 1> The liquid crystal display device shown in FIG. 11 of the third embodiment uses diodes as transistors in the driving circuit section. It is made using a transistor with an aluminum gate structure, but as shown in Figure 12, The driver circuit shown in FIG. 1 includes a transistor 102a with a dual gate structure, and 10 may be used in the pixel portion shown in FIG.

[0252] The transistor 103a is a conductive film that functions as a gate electrode and is provided over the substrate 302. 304c, insulating films 305 and 306 functioning as the gate insulating film 51, and a and a source electrode in contact with the oxide semiconductor film 308b. and conductive films 310d and 310e functioning as drain electrodes. An inorganic insulating film 53 is formed on the conductive film 308b and the conductive films 310d and 310e. A conductive film 316e functioning as a gate electrode is formed on the film 53. The conductive film 316e is formed through an opening (FIG. (not shown) is connected to the conductive film 304c which functions as a gate electrode. The conductive film 304c and the conductive film 316e are at the same potential.

[0253] The pixel section, together with the driver circuit section, is made of highly reliable, large on-current, and high field-effect mobility By providing a transistor with a dual gate structure, a liquid crystal display device with excellent display quality can be created. It can be manufactured.

[0254] <Variation 2> In the liquid crystal display device shown in the second or third embodiment, as shown in FIG. The organic insulating film 3 is a region that overlaps with the transistor 102a provided in the driving circuit section. A conductive film 319b formed at the same time as the conductive film 319 may be provided on the conductive film 317. 9b can be set to any potential such as a common potential or a ground potential. By providing the conductive film 319b overlapping with the transistor 102a, the transistor 102a The conductive film 316d functions as a gate electrode of the As a result, the misalignment of the liquid crystal layer 321 due to the electric field can be prevented. It can prevent good.

[0255] <Variation 3> In the second or third embodiment, the organic insulating film 317 is formed in the driving circuit section and the pixel section. 14, the liquid crystal display device having the organic insulating film 31 only in the pixel portion has been described. 7a may be provided.

[0256] In the liquid crystal display device shown in FIG. 14, the insulating film 313 is formed as shown in FIG. After that, a mask is formed by patterning, and insulating films 305 and 306 are formed using the mask. 06, 312, and 313 are etched to form openings. Next, as shown in FIG. After forming the conductive film 315 shown in FIG. 8(B), the conductive film 316b shown in FIG. 8(C) is formed. A conductive film 316a is formed to connect the conductive film 304b and the conductive film 310c. An organic insulating film 317a and a conductive film 319 are formed.

[0257] As shown in FIG. 15, when the organic insulating film 317a is not provided in the drive circuit section, On the conductive film 316d functioning as the gate electrode of the double-gate transistor 102b, A conductive film 319a formed simultaneously with the conductive film 319 may be provided.

[0258] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0259] (Fourth embodiment) In this embodiment, a semiconductor device according to one embodiment of the present invention will be described with reference to drawings. .

[0260] FIG. 16 is a cross-sectional view of a transistor 103 and a capacitor 105 included in the semiconductor device. .

[0261] The transistor 103 shown in FIG. 16A has a gate electrode provided over a substrate 302. and a gate insulating film formed on the substrate 302 and the conductive film 304c. the oxide semiconductor film 308b overlapping with the conductive film 304c with the gate insulating film 51 interposed therebetween; a pair of electrodes functioning as a source electrode and a drain electrode which are in contact with the oxide semiconductor film 308b; The conductive film 310d has a conductive film 310e.

[0262] Furthermore, a metal oxide film 308c is provided on the gate insulating film 51. The conductive film 308c is one of a pair of conductive films 310e included in the transistor 103. In addition, an inorganic insulating film 53 is formed on the transistor 102 and the metal oxide film 308c. A conductive film 316b is provided on the inorganic insulating film 53. A metal oxide film 308c The capacitor element 105 is formed by the inorganic insulating film 53 and the conductive film 316b.

[0263] In addition, an organic insulating film 317 is provided on the inorganic insulating film 53 and the conductive film 316b. In addition, in the openings provided in the inorganic insulating film 53 and the organic insulating film 317, the conductive film 310e A conductive film 319 is provided on the organic insulating film 317. It functions as a pole.

[0264] The metal oxide film 308c is an oxide semiconductor film formed at the same time as the oxide semiconductor film 308b. hydrogen, boron, phosphorus, nitrogen, tin, antimony, rare gas elements, alkali metals, alkalis By introducing impurities such as lithium-earth metals or oxygen deficiencies, the conductivity is improved, and the conductive Note that since the oxide semiconductor film has a light-transmitting property, the metal oxide film 308c also becomes a light-transmitting film. It has photosensitivity.

[0265] The conductive film 316b and the conductive film 319 are formed using a light-transmitting conductive film. Therefore, the capacitor 105 has a light-transmitting property. It is possible to reduce the capacitance of the capacitor element and increase the aperture ratio of the pixel. .

[0266] The conductive film 319 formed on the organic insulating film 317 is connected to the transistor 103. The conductive film 319 functions as a pixel electrode, and is connected to the inorganic insulating film 53 and the organic insulating film 317 via the inorganic insulating film 53 and the organic insulating film 317. That is, the conductive film 319 is spaced apart from the transistor 103. Since the distance is large, the potential of the conductive film 310d of the transistor 103 does not have much influence on the conductive film 310d. As a result, the conductive film 319 can overlap with the transistor 103, and the pixel opening can be You can increase your speaking rate.

[0267] The transistor 103 of this embodiment shown in FIG. 16 has an organic insulating film formed on an inorganic insulating film 53. The organic insulating film 317 has a thickness of 500 nm or more. An electric field is generated by applying a negative voltage to the conductive film 304c that functions as a negative electrode. The influence of the above does not reach the surface of the organic insulating film 317, and positive charges are generated on the surface of the organic insulating film 317. In addition, the organic insulating film 317 is thick, having a thickness of 500 nm or more, and therefore has a large air gap. Even if positively charged particles contained in the air are adsorbed on the surface of the organic insulating film 317, the organic insulating film 31 The electric field of the positively charged particles adsorbed on the surface of the oxide semiconductor film 308b and the inorganic insulating film 53 As a result, the interface between the oxide semiconductor film 308b and the inorganic insulating film 53 is hardly affected. At the interface, a state where a positive bias is not substantially applied is not formed, and the threshold voltage of the transistor is The fluctuation of the voltage is small.

[0268] In addition, water and the like easily diffuse into the organic insulating film 317, but the inorganic insulating film 53 is made of a nitride. By having an insulating film, the nitride insulating film acts as a barrier film for water, preventing it from diffusing into the organic insulating film 317. This can prevent the water from diffusing into the oxide semiconductor film 308b.

[0269] From the above, by providing the organic insulating film 317 on the transistor, It is possible to reduce variations in electrical characteristics. In addition, it has normally-off characteristics and high reliability. In addition, the organic insulating film can be formed by a printing method or a coating method. Since it is possible to form the film using a material such as a silicon dioxide, the manufacturing time can be reduced. By providing a conductive film that functions as a pixel electrode on the organic insulating film 317, You can increase your speaking rate.

[0270] <Variation 1> A modification of the transistor shown in FIG. 16A will be described with reference to FIG. The transistor 103 in this modification is a transistor including an oxide semiconductor film formed using a multi-tone mask. 308e and a pair of conductive films 310f and 310g. The resistor 103 and the capacitor element 105 are connected by a conductive film 319 that functions as a pixel electrode. It is characterized by the presence of

[0271] In addition, in FIG. 16(B), a metal oxide film 308f is formed on the gate insulating film 51. In addition, a conductive film formed on the metal oxide film 308f at the same time as the conductive films 310f and 310g is The conductive film 310h is connected to the conductive film 310g. As a result, the transistor 103 and the capacitor 105 are electrically connected to each other. As shown in FIG. 16C, a channel protective transistor 103d and a capacitor 105 However, they may be connected by a conductive film 319 that functions as a pixel electrode.

[0272] <Variation 2> In the display device shown in the fourth embodiment, in some cases or depending on the situation, for example, For example, the conductive film 319 may be formed using a conductive film that has a function of reflecting light.

[0273] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0274] (Embodiment 5) In this embodiment, a semiconductor device according to one embodiment of the present invention and a manufacturing method thereof will be described with reference to drawings. Please refer to the following for explanation.

[0275] In this embodiment, a display device will be described as an example of a semiconductor device. The circuit diagram of the pixel shown in FIG. 2 can be used as appropriate.

[0276] The specific configuration of the element substrate included in the display device will be described. A VA type liquid crystal display device is used, and a top view of a pixel 301 included in the liquid crystal display device is shown. Shown in Figure 17.

[0277] In FIG. 17, the conductive film 304c functioning as a scanning line is a conductive film 304b functioning as a signal line. It is provided so as to extend in a direction substantially perpendicular to the film (the left-right direction in the figure). The conductive film 310d extends in a direction (vertical direction in the drawing) substantially perpendicular to the conductive film functioning as the scanning line. It is provided by extending it.

[0278] The transistor 103 includes a conductive film serving as a scan line and a conductive film serving as a signal line. The transistor 103 is provided in a region where the gate electrodes are connected. a conductive film 304c, a gate insulating film (not shown in FIG. 17), a channel formed on the gate insulating film, The oxide semiconductor film 308b in which the channel region is formed functions as a source electrode and a drain electrode. The conductive film 310 is made up of a pair of conductive films 310d and 310e.

[0279] The metal oxide film 308c is connected to the conductive film 310e included in the transistor 103. In addition, a conductive film 316b is provided over the metal oxide film 308c with an insulating film interposed therebetween. In addition, in the insulating film provided on the metal oxide film 308c, An opening 362 is provided. In the opening 362, the metal oxide film 308c is The insulating film is in contact with the nitride insulating film (not shown in FIG. 17) included in the insulating film.

[0280] The capacitor 105 is formed in a region where the metal oxide film 308c and the conductive film 316b overlap each other. The metal oxide film 308c and the conductive film 316b have light-transmitting properties. has light-transmitting properties.

[0281] The conductive film 319 functioning as a pixel electrode is formed on the substrate 310 via an organic insulating film (not shown in FIG. 17). The conductive film 319 is provided on the conductive film 310e and the conductive film 316b. 64c is connected to the conductive film 310e. 05 and the conductive film 319 are electrically connected.

[0282] Next, a cross-sectional view taken along the dashed line CD in FIG. 17 is shown in FIG. 18. In this case, a driving circuit section (top view omitted) including a scanning line driving circuit 14 and a signal line driving circuit 16 is ) is shown in a cross-sectional view taken along the line AB. In this embodiment, a VA type semiconductor device is used. A liquid crystal display device will now be described.

[0283] The liquid crystal display device described in this embodiment has a liquid crystal display device between a pair of substrates (a substrate 302 and a substrate 342). The element 322 is sandwiched.

[0284] The liquid crystal element 322 is made up of a conductive film 316b above the substrate 302 and a film for controlling the orientation (hereinafter referred to as , alignment films 320 and 352), a liquid crystal layer 321, and a conductive film 350.

[0285] In the driving circuit section, a conductive film 304a functioning as a gate electrode, a gate insulating film 51, and the insulating film 305 and the insulating film 306 that function as a channel region; and the oxide semiconductor film in which the channel region is formed. 308a, and conductive films 310a and 310b functioning as source and drain electrodes. The oxide semiconductor film 308a forms the transistor 102. can be done.

[0286] In the pixel portion, a conductive film 304c serving as a gate electrode and a gate insulating film 51 The insulating film 305 and the insulating film 306 function, and the channel region formed on the gate insulating film 51 the oxide semiconductor film 308b, which is formed with a conductive layer serving as a source electrode and a drain electrode; The films 310d and 310e constitute the transistor 103. The oxide semiconductor film 308b , are provided on the gate insulating film 51. In addition, inorganic insulating films are provided on the conductive films 310d and 310e. The insulating films 312 and 314, which are the film 53, are provided as protective films.

[0287] Also, a metal oxide film 308c functions as one electrode, and an insulating film functions as a dielectric film. The film 314 and the conductive film 316b functioning as the other electrode form a capacitor 105. The metal oxide film 308c is provided on the gate insulating film 51.

[0288] An organic insulating film 317 is formed on the inorganic insulating film 53. In addition, on the organic insulating film 317, A conductive film 319 that functions as a pixel electrode is formed. 19 is connected by a conductive film 310e.

[0289] In the driving circuit section, the conductive film 304a and the conductive film 304c are formed at the same time. 4b and the conductive film 31 formed simultaneously with the conductive films 310a, 310b, 310d, and 310e. The conductive film 319 is connected to the electrode 0c through a conductive film 319a formed at the same time as the conductive film 319.

[0290] The conductive film 304a and the conductive film 319a are formed by the insulating film 305, the insulating film 306, the insulating film 312, The conductive film 310c and the conductive film 310d are connected to each other through an opening provided in the organic insulating film 317. The conductive film 319a is formed through an opening provided in the insulating film 312, the insulating film 314, and the organic insulating film 317. Connect at the part.

[0291] Although not shown, the conductive film 316b was formed simultaneously with the conductive films 319 and 319a. A conductive film formed simultaneously with the conductive films 304a, 304b, and 304c, or Conductive films formed simultaneously with the conductive films 310a, 310b, 310c, 310d, and 310e In addition, the conductive films 304a, 304b, and 304c are formed at the same time. or conductive films 310a, 310b, 310c, 310d, and 310e. Any potential such as a common potential or a ground potential is applied to the conductive film 316b through the conductive film. .

[0292] The components of the display device shown in FIG. 18 will now be described.

[0293] Conductive films 304a, 304b, and 304c are formed on the substrate 302. The conductive film 04a functions as a gate electrode of a transistor in the driver circuit portion. The conductive film 304b is formed in the driving circuit section and is connected to the conductive film 310c. is formed in the pixel section 11 and functions as a gate electrode of the transistor in the pixel section.

[0294] An insulating film 305, an insulating film 306, an insulating film 307, an insulating film 308, an insulating film 309, an insulating film 309a, an insulating film 309c, and an insulating film 309b are formed on the substrate 302 and the conductive films 304a, 304c, and 304b. The insulating film 305 and the insulating film 306 are formed on the transistors in the driver circuit section. The gate insulating film 51 functions as the gate insulating film 51 of the transistor in the pixel section 11. do.

[0295] Oxide semiconductor films 308a and 308b and a metal oxide film 308c are formed over the insulating film 306. The oxide semiconductor film 308a is formed so as to overlap with the conductive film 304a. The oxide semiconductor film 308 functions as a channel region of a transistor in the driver circuit portion. b is formed in a position overlapping with the conductive film 304c, and is a channel region of a transistor in a pixel portion. The metal oxide film 308c functions as a conductive film 310 included in the transistor 103. e and serves as an electrode of the capacitor 105.

[0296] In the liquid crystal display device described in this embodiment, the capacitor element has a light-transmitting property. The aperture ratio of the pixel can be increased while increasing the area occupied by the pixel.

[0297] The insulating film 306, the oxide semiconductor films 308a and 308b, the metal oxide film 308c, and the conductive film On the films 310a, 310b, 310c, 310d, and 310e, the inorganic insulating film 53 is formed. An insulating film 312 and an insulating film 314 are formed.

[0298] The conductive film 316b is formed over the insulating film 314 and can function as an electrode of a capacitor. can.

[0299] An organic insulating film 317 is formed on the inorganic insulating film 53 and the conductive film 316b.

[0300] Conductive films 319 and 319a are formed on the organic insulating film 317. The conductive film 319a functions as a pixel electrode. 22A.) and is electrically connected to the conductive film 310a in the opening 364b (see FIG. 22A). ) is electrically connected to the conductive film 310c. It functions as a connection electrode for connecting 10c.

[0301] In order to form a connection structure in which the conductive film 304a and the conductive film 310c are in direct contact with each other, Before forming the conductive film 310c, a pattern is formed in order to form openings in the insulating films 305 and 306. However, as shown in Figure 18, The conductive film 304a and the conductive film 310c are connected by the film 319a. Therefore, it is not necessary to form a connection portion where the conductive film 310a and the conductive film 310c are in direct contact with each other, and the photomask can be used only once. That is, it is possible to reduce the manufacturing process of the liquid crystal display device. .

[0302] The alignment film 320 is preferably light-transmitting, and is typically made of acrylic resin, Organic resins such as polyimide and epoxy resins can be used.

[0303] Furthermore, a colored film 346 is formed on the substrate 342. The colored film 346 is a color film. The light-shielding film 344 adjacent to the colored film 346 functions as a filter. The light-shielding film 344 functions as a black matrix. 46 is not necessarily provided, and may be provided in the case where the liquid crystal display device is monochrome, for example. The color film 346 may not be provided.

[0304] An insulating film 348 is formed on the colored film 346. The insulating film 348 is formed by a planarizing method. The function of the colored film 346 is to prevent impurities contained therein from diffusing toward the liquid crystal element. It has the function of controlling

[0305] In addition, a conductive film 350 is formed on the insulating film 348. The conductive film 350 is The conductive film 319 and the conductive film 311 function as the other of the pair of electrodes of the liquid crystal element. An alignment film 352 is formed on the liquid crystal display panel 9 a and the conductive film 350 .

[0306] In addition, a liquid crystal layer 321 is formed between the conductive films 319, 319a and the conductive film 350. The liquid crystal layer 321 is bonded to the substrate 302 and the substrate 342 using a sealing material (not shown). The seal is made of a material that prevents moisture from entering from the outside. In particular, a configuration in which the inorganic material is in contact with the inorganic material is preferred.

[0307] In addition, the thickness of the liquid crystal layer 321 (cell gap) is set between the conductive films 319, 319a and the conductive film 350. A spacer may be provided to maintain the gap (also called a gap).

[0308] A method for manufacturing an element portion provided on a substrate 302 shown in the liquid crystal display device shown in FIG. 5 and 19 to 21.

[0309] As in the second embodiment, the steps of FIGS. 5(A) to 5(C) are carried out to form a conductive film on the substrate 302. The conductive films 304a, 304b, and 304c, the insulating film 305, the insulating film 306, and the island-shaped oxide Semiconductor films 308a, 308b, and 308d are formed. Conductive films 304a, 304b, and 304c are formed by mask formation and etching processes. In addition, the formation of a mask by the second patterning and the etching process are performed to form an oxide semiconductor. The membranes 308a, 308b, and 308d are formed.

[0310] After that, heat treatment is performed in a manner similar to that in Embodiment 2 to form the oxide semiconductor film 308a. Hydrogen, water, and the like contained in the oxide semiconductor films 308b and 308d are released. The hydrogen concentration and water concentration contained in 308b and 308d may be reduced. As a result, the high purity is obtained. In addition, oxide semiconductor films 308a, 308b, and 308d can be formed. The temperature is typically 250°C or higher and 650°C or lower, preferably 300°C or higher and 500°C or lower. The temperature of the heat treatment is typically 300° C. or higher and 400° C. or lower, preferably By setting the temperature at 320℃ or higher and 370℃ or lower, warping and shrinkage of the substrate can be prevented even in large area substrates. This allows for a reduction in costs and improves yield.

[0311] In addition, when the film formation temperature of the insulating film 311a to be formed later is set to 280° C. or more and 400° C. or less, In this case, hydrogen, water, and the like contained in the oxide semiconductor films 308a, 308b, and 308d are released. Therefore, the heat treatment is not necessary.

[0312] Next, as in Embodiment 2, the insulating film 306 and the oxide semiconductor films 308a and 308b A conductive film 309 is formed over the insulating film 308d (see FIG. 19(A)).

[0313] Next, similarly to the second embodiment, the conductive film 309 is processed into a desired shape, thereby forming the conductive film 3 10a, 310b, 310c, 310d, and 310e are formed. 310b, 310c, 310d, and 310e are patterns formed by third patterning into a desired shape. The mask is formed by etching the area not covered by the mask. (See FIG. 19B). Note that the conductive film 310e is formed on the oxide semiconductor film 308b. and is in contact with the oxide semiconductor film 308d.

[0314] Next, as in Embodiment 2, the insulating film 306, the oxide semiconductor films 308a, 308b, and 308c are 08d, and the conductive films 310a, 310b, 310c, 310d, and 310e. , an insulating film 311 is formed in which insulating films 311a and 311b are stacked (see FIG. 19C). The insulating film 311 can be formed by using a sputtering method, a CVD method, a vapor deposition method, or the like. Cut.

[0315] Next, heat treatment is performed in the same manner as in the second embodiment. The temperature of the heat treatment is typically 1 50°C or higher and lower than the substrate strain point, preferably 200°C or higher and 450°C or lower, more preferably 30 The temperature of the heat treatment is typically 300°C or higher and 450°C or lower. 00℃ or less, preferably 320℃ to 370℃, It is possible to reduce warpage and shrinkage of the substrate, improving yield.

[0316] By this heat treatment, part of oxygen contained in the insulating film 311b is oxidized to the oxide semiconductor film 308a , 308b, and 308d, and the oxide semiconductor films 308a, 308b, and 308d are formed by the transfer of the oxide semiconductor film 308a, 308b, and 308d. As a result, the amount of oxygen vacancies can be reduced. The amount of oxygen vacancies contained in 8b and 308d can be further reduced.

[0317] In addition, when the insulating films 311a and 312b contain water, hydrogen, etc., the insulating films 311a and 312b are used to block the water, hydrogen, etc. An insulating film 313 having a function of blocking is formed later, and then heat treatment is performed to form the insulating film 311a. Water, hydrogen, and the like contained in the oxide semiconductor film 311b move to the oxide semiconductor films 308a, 308b, and 308d. However, defects occur in the oxide semiconductor films 308a, 308b, and 308d. By this heating, water, hydrogen, etc. contained in the insulating films 311a and 311b can be desorbed. This reduces variations in the electrical characteristics of the transistors and also reduces variations in the threshold voltage. can be suppressed.

[0318] In addition, by forming the insulating film 311b on the insulating film 311a while heating, an oxide semiconductor Oxygen is transferred to the oxide semiconductor films 308a, 308b, and 308d. b, 308d, it is possible to reduce the amount of oxygen vacancies contained in the It is not necessary.

[0319] Note that the heat treatment may be performed after the opening 362, which will be formed later, is formed.

[0320] Next, in the same manner as in the second embodiment, the insulating film 311 is processed into a desired shape, thereby forming the insulating film 3 The insulating film 311 and the opening 362 are formed. A mask is formed on the shape by a fourth patterning, and the area not covered by the mask is It can be formed by etching (see FIG. 20(A)).

[0321] Note that the opening 362 is formed so that the surface of the oxide semiconductor film 308d is exposed.

[0322] Next, in a manner similar to that of Embodiment 2, the insulating film 312 is formed over the oxide semiconductor film 308d. 13 is formed (see FIG. 20(B)).

[0323] Next, similarly to the second embodiment, a conductive film 315 is formed on the insulating film 314 (FIG. 21(A) )reference.).

[0324] Next, the conductive film 315 is processed into a desired shape to form 316b. The film 316b is formed into a desired shape by a mask using a fifth patterning process. It can be formed by etching the uncovered areas (see Figure 21(B)). ).

[0325] Next, an organic insulating film 317 is formed so as to cover the insulating film 314 and the conductive film 316b (FIG. 2 1(C). The organic insulating film 317, which functions as a planarizing film, is formed between the insulating film 313 and the conductive film. Each membrane 316b has an opening so that a portion thereof is exposed.

[0326] Next, using the organic insulating film 317 as a mask, the insulating films 305, 306, and 312 are and the insulating film 313 are etched to form openings exposing the conductive film 304b. 364a, an opening 364b exposing the conductive film 310c, and an opening 364b exposing the conductive film 310e. 364c is formed (see FIG. 22(A)).

[0327] Next, similarly to Embodiment Mode 2, a conductive film 318 is formed (see FIG. 22B).

[0328] Next, similarly to the second embodiment, the conductive film 318 is processed into a desired shape, thereby forming the conductive film 3 The conductive films 319 and 319a are formed in a desired shape by forming a seventh pattern. A mask is formed by etching, and the area not covered by the mask is etched. (See FIG. 22(C)).

[0329] Through the above steps, a pixel portion having a transistor and a driver circuit portion are formed on the substrate 302. In the manufacturing process shown in this embodiment, the first to seventh patterns can be formed. This means that transistors and capacitors can be formed simultaneously using seven photomasks. can be done.

[0330] In addition, the element portion provided on the substrate 342 provided opposite to the substrate 302 is The manufacturing process of the second embodiment shown in FIG. 10 can be appropriately used to form the semiconductor device.

[0331] Next, as in the second embodiment, on the substrate 302 and the substrate 342, more specifically on the substrate 302 The insulating film 314 and the conductive films 319 and 319a formed on the substrate 342 are An alignment film 320 and an alignment film 352 are formed on the film 350, respectively. A liquid crystal layer 321 is formed between the substrate 342 and the liquid crystal layer 321 .

[0332] Through the above steps, the liquid crystal display device shown in FIG. 18 can be manufactured.

[0333] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0334] (Embodiment 6) In this embodiment, a liquid crystal display device including a transistor different from that in Embodiment 4 will be described. This will be explained using FIGS. 23 to 27.

[0335] The liquid crystal display device shown in FIG. 23 has a dual gate structure in the drive circuit section indicated by AB. The semiconductor device is characterized by including a transistor 102a.

[0336] The transistor 102a provided in the driver circuit portion is the same as the transistor 102 described in Embodiment 2. It has the same structure as 02a.

[0337] <Variation 1> The liquid crystal display device shown in FIG. 23 of the sixth embodiment uses diodes as transistors in the driving circuit section. It is made using a transistor with an aluminum gate structure, but as shown in Figure 24, The driver circuit shown in FIG. 1 includes a transistor 102a with a dual gate structure, and 10 may be used in the pixel portion shown in FIG.

[0338] The transistor 103a has a structure similar to that of the transistor 103a described in Embodiment 2. do.

[0339] The pixel section, together with the driver circuit section, is made of highly reliable, large on-current, and high field-effect mobility By providing a transistor with a dual gate structure, a liquid crystal display device with excellent display quality can be created. It can be manufactured.

[0340] <Variation 2> In the liquid crystal display device shown in the fifth or sixth embodiment, as shown in FIG. The organic insulating film 3 is a region that overlaps with the transistor 102a provided in the driving circuit section. A conductive film 319b formed at the same time as the conductive film 319 may be provided on the conductive film 317. 9b can be set to any potential such as a common potential or a ground potential. By providing the conductive film 319b overlapping with the transistor 102a, the transistor 102a The conductive film 316d functions as a gate electrode of the As a result, the misalignment of the liquid crystal layer 321 due to the electric field can be prevented. It can prevent good.

[0341] <Variation 3> In the fifth or sixth embodiment, the organic insulating film 317 is formed in the driving circuit section and the pixel section. 26, the liquid crystal display device having the organic insulating film 31 only in the pixel portion has been described. 7a may be provided.

[0342] As shown in FIG. 27, when the organic insulating film 317a is not provided in the drive circuit section, On the conductive film 316d functioning as the gate electrode of the double-gate transistor 102b, A conductive film 319a formed simultaneously with the conductive film 319 may be provided.

[0343] <Variation 4> In the fifth and sixth embodiments, a liquid crystal element is used as an example of a display element. However, various display elements can be used. For example, an organic EL element is used. Examples of such a display are shown in Figures 28, 29, 30, and 31. The device is made of organic resin film 371 such as acrylic resin, polyimide, epoxy resin, etc., and organic resin film 3 71 and a common electrode 375 provided on the EL layer 373. The conductive film 319, the EL layer 373, and the common electrode 375 constitute an organic EL element. Complete.

[0344] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0345] (Embodiment 7) In this embodiment, the second and third embodiments, the fourth and fifth embodiments are In comparison, the process requires one more photomask, that is, eight photomasks are used. A liquid crystal display device including such a transistor and a capacitor will be described with reference to FIG.

[0346] The liquid crystal display device shown in FIG. 32 has an opening 36 formed in an insulating film 312 and an insulating film 314. 3, the conductive film 316b and the conductive film 310e included in the transistor 103 are It is characterized by being connected to the membrane 319.

[0347] In the liquid crystal display device described in this embodiment, the transistor 103 and the capacitor 105 are connected to each other. The opening for the transistor 103 is connected to the conductive film 319 which functions as a pixel electrode. That is, the conductive film 310e included in the transistor 103 and the capacitor 104 overlap with each other. The opening to which the conductive film 316b included in the capacitor 105 is connected and the opening to which the conductive film 316b included in the transistor 103 is connected are connected. The conductive film 310e overlaps with an opening where the conductive film 319 functioning as a pixel electrode is connected. This makes it possible to increase the aperture ratio of each pixel.

[0348] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0349] (Embodiment 8) In this embodiment, a transistor having a structure different from that of the transistors described in Embodiments 2 to 7 is A liquid crystal display device including a transistor will be described with reference to FIGS.

[0350] The liquid crystal display device shown in FIG. 33 has a structure similar to that of the liquid crystal display devices shown in Embodiments 2 to 7. In comparison, the difference is that a channel protection type transistor is used.

[0351] The liquid crystal display device shown in FIG. 33 has a structure similar to that of the liquid crystal display devices shown in Embodiments 2 to 7. In contrast, in the opening of the insulating film 392, the oxide semiconductor film 308a, the conductive film 310a, The oxide semiconductor film 308b is connected to the conductive films 310d and 310e. In addition, the insulating film 394 is provided between the insulating film 314 and the conductive film 316b. The points are different.

[0352] In the driving circuit section, a conductive film 304a functioning as a gate electrode, a gate insulating film 51, and the insulating film 305 and the insulating film 306 that function as a channel region; and the oxide semiconductor film in which the channel region is formed. 308a, an insulating film 392 covering the oxide semiconductor film 308a, and an opening in the insulating film 392. The conductive film 31 which is in contact with the oxide semiconductor film 308a and functions as a source electrode and a drain electrode The conductive films 310a and 310b constitute the transistor 102c. On the insulating films 310b and 310c, an insulating film 312, an insulating film 314, and an insulating film 394 are provided. .

[0353] In the pixel portion, a conductive film 304c functions as a gate electrode, and a gate insulating film The insulating film 305 and the insulating film 306 are connected to the gate insulating film, and the channel region is formed on the insulating film. an oxide semiconductor film 308b covered with the insulating film 392; The oxide semiconductor film 308b is in contact with the oxide semiconductor film 308b in the opening 2, and serves as a source electrode and a drain electrode. The transistor 103b is formed by the functioning conductive films 310d and 310e. An insulating film 312, an insulating film 314, and an insulating film 394 are provided on the films 310d and 310e. It is being done.

[0354] In addition, a conductive film 316b is provided on the insulating film 314.

[0355] In addition, the metal oxide film 308c functions as an electrode, and the insulating film 31 functions as a dielectric film. 4, the insulating film 394, and the conductive film 316b functioning as an electrode constitute a capacitor element 105. do.

[0356] The insulating film 392 is formed of an oxide insulating film because it is in contact with the oxide semiconductor films 308a and 308b. The insulating film 392 is preferably formed using a material similar to that of the insulating film 306. The insulating film 392 can be formed of an oxide insulating film that is permeable to oxygen, similar to the insulating film 312a. As a result, the oxygen contained in the insulating film 312b is The oxide semiconductor film 308a and 308b can be transferred to the oxide semiconductor film 30 The amount of oxygen vacancies in the oxide semiconductors 8a and 308b can be reduced. It is preferable that the number of defects at the interfaces between the films 308a and 308b and the insulating film 392 is small.

[0357] The insulating film 394 is provided to control the capacitance value of the capacitor 105. The insulating film 394 can be formed using an oxide insulating film or a nitride insulating film as appropriate. The insulating film 394 is formed by a CVD method (chemical vapor deposition method) using organic silane gas. By using an oxide insulating film, typically a silicon oxide film, it is possible to improve the flatness. The insulating film 314 is preferable because it allows the capacitor 105 to have a predetermined capacitance value. If this is possible, the insulating film 394 does not need to be provided.

[0358] In this modification, the oxide semiconductor films 308a and 308b are covered with an insulating film 392. Therefore, the conductive films 310a, 310b, 310d, and 310e are formed by etching. Therefore, the oxide semiconductor films 308a and 308b are not damaged. It is formed of an oxide insulating film containing more oxygen than the oxygen that satisfies the stoichiometric composition. Therefore, part of oxygen contained in the insulating film 312 is transferred to the oxide semiconductor films 308a and 308b. This can reduce the amount of oxygen vacancies in the oxide semiconductor films 308a and 308b.

[0359] An organic insulating film 317 is provided on the insulating film 394 and the conductive film 316b.

[0360] Conductive films 319 and 319a are formed on the organic insulating film 317. The conductive film 319a functions as a pixel electrode. 36(C). ) is electrically connected to the conductive film 310c. It functions as a connection electrode for connecting 10c.

[0361] A method for manufacturing an element portion provided on a substrate 302 shown in the liquid crystal display device shown in FIG. This will be explained using FIG. 5 and FIG. 34 to FIG.

[0362] As in the first embodiment, a gate electrode is formed on a substrate 302 through the steps shown in FIGS. Conductive films 304a, 304b, and 304c function as gate electrodes, and a gate insulating film The insulating film 305 and the insulating film 306 are formed of oxide semiconductor films 308a, 308b, and 308d. In this process, first patterning and second patterning are performed, The conductive films 304a, 304b, and 304c, the oxide semiconductor films 308a, 308b, and 308c are It forms 08d.

[0363] Next, as shown in Fig. 34(A), an insulating film 390 is formed. It is formed under the same conditions as those for 305 or insulating film 311a.

[0364] Next, the insulating film 390 is processed into a desired shape, thereby forming an opening as shown in FIG. An insulating film 392 having portions 391, 391a, 391b, 391c, and 391d is formed. The insulating film 392 is formed into a desired shape by forming a mask by a third patterning. It can be formed by etching the areas not covered by the mask.

[0365] Next, after a conductive film is formed over the oxide semiconductor films 308a and 308b and the insulating film 392, Conductive films 310a, 310b, 310c, 310d, and 310e are formed through the same process as in the first embodiment. 34(C)). , 310d, 310e, forming a mask by fourth patterning into a desired shape; The region not covered by the mask can be etched to form the insulating film.

[0366] Next, the insulating film 392 and the conductive films 310a, 310b, 310c, 310d, and 310e An insulating film 311 is formed thereon (see FIG. 35(A)).

[0367] Next, the insulating film 311 is processed into a desired shape, thereby forming the insulating film 311 having the opening 393. The insulating film 312 and the opening 393 are patterned in a desired shape by the fifth patterning. The mask is formed by etching the area not covered by the mask. This can be achieved (see FIG. 35(B)).

[0368] Next, as shown in FIG. 35C, the oxide semiconductor film 308d, the insulating film 392, and the opening An insulating film 313 and an insulating film 394 are formed to cover the film 393 .

[0369] The insulating film 394 is formed by a CVD method, a sputtering method, or the like.

[0370] Next, a conductive film is formed on the insulating film 394, and then the conductive film is formed by the same process as in the first embodiment. 316b (see FIG. 36(A)). Note that the conductive films 316a and 316b are A mask is formed by a sixth patterning in the shape of It can be formed by etching.

[0371] Next, as shown in FIG. 36(B), an organic insulating film 317 is formed in the same manner as in the second embodiment. The organic insulating film 317 is formed by photolithography using the sixth photomask shown in the second embodiment. It should be noted that in this embodiment, This step corresponds to the seventh patterning.

[0372] Next, using the organic insulating film 317 as a mask, the insulating films 305, 306, and 312 are The insulating film 313 and the insulating film 394 are partly etched to form the conductive film 304b. an opening 364a exposing the conductive film 310c; an opening 364b exposing the conductive film 310e; An opening 364c exposing the conductive film 316b and an opening 364d exposing the conductive film 316b are formed (see FIG. See 36(C). ).

[0373] Next, after forming the conductive film, the conductive films 319 and 319a are formed through the same process as in the first embodiment. The conductive films 319 and 319a are formed in a desired shape. A mask is formed by turning, and the area not covered by the mask is etched. It can be formed by

[0374] Through the above steps, a pixel portion having a transistor and a driver circuit portion are formed on the substrate 302. In the manufacturing process shown in this embodiment, the first to eighth patterns can be formed. This means that transistors and capacitors are formed simultaneously using eight photomasks. can be done.

[0375] In the first to eighth embodiments, a liquid crystal element is used as an example of a display element. However, various display elements can be used. For example, an organic EL element is used. Examples of the case where an organic EL element is used are shown in Figures 38, 39, 40, 41, and 42. The display device is made of organic resin film 371 such as acrylic resin, polyimide, epoxy resin, etc. The EL layer 373 is provided on the resin film, and the common electrode 375 is provided on the EL layer. The conductive film 319, the EL layer 373, and the common electrode 375 constitute an organic EL element. do.

[0376] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0377] (Embodiment 9) The transistors 102, 102a, 102b, and 10 In 2c, 103, 103a, and 103b, an oxide semiconductor film may be formed as a stacked structure as needed. Here, the transistor 103 will be used for description.

[0378] The transistor shown in FIG. 43 has an oxide film between the insulating film 306 and the conductive films 310d and 310e. A multilayer film 336 including a nitride semiconductor film is formed.

[0379] The multilayer film 336 includes an oxide semiconductor film 336a and an oxide semiconductor film 336b. The multilayer film 336 has a two-layer structure. In addition, an insulating film 312a is formed so as to contact the multilayer film 336. The oxide semiconductor film 336b is formed in contact with the insulating film 312a. An oxide semiconductor film 336b is provided between the oxide semiconductor film 336a and the insulating film 312a. do.

[0380] The oxide semiconductor film 336b is composed of one or more of the elements constituting the oxide semiconductor film 336a. The oxide semiconductor film 336b is formed by adding at least one of the elements forming the oxide semiconductor film 336a. Since the oxide semiconductor film 336a is formed from above, the oxide semiconductor film 336b is Therefore, the movement of carriers is not hindered at the interface. Therefore, the field effect mobility of the transistor is increased.

[0381] The oxide semiconductor film 336b is typically an In—Ga oxide film, an In—Zn oxide film, In-M-Zn oxide film (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn or or Hf), and the energy of the bottom of the conduction band is lower than that of the oxide semiconductor film 336a. The energy level is typically close to the energy level of the bottom of the conduction band of the oxide semiconductor film 336b. The difference in energy between the lower end of the conduction band of the compound semiconductor film 336a and the lower end of the conduction band of the compound semiconductor film 336b is 0.05 eV or more, and 0.07 eV or more. eV or more, 0.1 eV or more, or 0.15 eV or more and 2 eV or less, 1 eV or less, 0 That is, the electron affinity of the oxide semiconductor film 336b is 0.5 eV or less, or 0.4 eV or less. the difference between the electron affinity of the oxide semiconductor film 336a and the electron affinity of the oxide semiconductor film 336b is 0.05 eV or more and 0.07 eV or less. or more, 0.1 eV or more, or 0.15 eV or more and 2 eV or less, 1 eV or less, 0.5 eV or less, or 0.4 eV or less.

[0382] The oxide semiconductor film 336b contains In, which increases carrier mobility (electron mobility). This is preferable because

[0383] The oxide semiconductor film 336b may include Al, Ti, Ga, Y, Zr, La, Ce, Nd, and S. Having n or Hf in a higher atomic ratio than In may have the following effects: (1) The energy gap of the oxide semiconductor film 336b is increased. (3) To reduce the electron affinity of the electrolyte membrane 336b. (4) To block impurities from the outside. (5) Al, Ti, Ga, Y, Z R, La, Ce, Nd, Sn, and Hf are metal elements with strong bonding strength with oxygen, so they are easily absorbed by the oxygen. This makes it less likely that element deficiency will occur.

[0384] When the oxide semiconductor film 336b is an In-M-Zn oxide, the atomic ratio of In to M is , In is less than 50 atomic % when the sum of In and M is 100 atomic %; M is more than 50 atomic %, and more preferably In is less than 25 atomic %; Let M be greater than 75 atomic%.

[0385] The oxide semiconductor film 336a and the oxide semiconductor film 336b are made of In-M-Zn oxide. (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn or Hf), oxidation Compared with the oxide semiconductor film 336a, the M (Al, Ti, G) contained in the oxide semiconductor film 336b is a, Y, Zr, La, Ce, Nd, Sn or Hf) atomic ratio is large, typically, The amount of the atoms contained in the oxide semiconductor film 336a is 1.5 times or more, preferably 2 times The atomic ratio is more preferably three times or more higher.

[0386] The oxide semiconductor film 336a and the oxide semiconductor film 336b are made of In-M-Zn oxide. (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn or Hf), oxidation The oxide semiconductor film 336b is In:M:Zn=x1:y1:z1 [atomic ratio], If 336a is In:M:Zn=x2:y2:z2 [atomic ratio], then y1 / x1 is y2 / x2, and preferably y1 / x1 is 1.5 times or more greater than y2 / x2. More preferably, y1 / x1 is at least twice as large as y2 / x2, and even more preferably, y 1 / x1 is more than three times greater than y2 / x2.

[0387] For example, the oxide semiconductor film 336a may be formed of In:Ga:Zn=1:1:1, In:Ga: Use In-Ga-Zn oxide with an atomic ratio of Zn=1:1:1.2 or 3:1:2 The oxide semiconductor film 336b can be formed by In:Ga:Zn=1:3:n (n is an integer between 2 and 8, 1:6:m (m is an integer between 2 and 10), or 1:9:6 In the oxide semiconductor film 33, an In-Ga-Zn oxide having an atomic ratio of 1000 to 10000 can be used. The atomic ratios of the oxide semiconductor film 6a and the oxide semiconductor film 336b are calculated by adding an error to the above atomic ratios. The temperature of the oxide semiconductor film 336a is within a range of ±20%. When the ratio is Ga or more, CAAC-OS is easily formed, which is preferable.

[0388] The oxide semiconductor film 336b is formed by forming an oxide semiconductor film when forming the insulating film 312b. It also functions as a film for reducing damage to the conductive film 336a.

[0389] The thickness of the oxide semiconductor film 336b is greater than or equal to 3 nm and less than or equal to 100 nm, preferably greater than or equal to 3 nm. It should be 50nm or less.

[0390] Similarly to the oxide semiconductor film 336a, the oxide semiconductor film 336b is, for example, a non-single-crystal oxide semiconductor film. The non-single crystal structure may be, for example, a CAAC-OS (C Axis Al igned Crystalline Oxide Semiconductor), This includes crystalline structures, microcrystalline structures (described below), and amorphous structures.

[0391] Note that the oxide semiconductor films 336a and 336b have an amorphous structure. region, microcrystalline structure region, polycrystalline structure region, CAAC-OS region, single crystal structure region A mixed film having two or more kinds of materials may be formed. The mixed film may have, for example, an amorphous structure region, a finely crystalline structure region, and the like. A region of crystalline structure, a region of polycrystalline structure, a region of CAAC-OS, or a region of single crystal structure There are cases where the mixed film has a single layer structure having two or more regions. region, microcrystalline structure region, polycrystalline structure region, CAAC-OS region, single crystal structure region In some cases, the film may have a laminated structure of two or more of the above regions.

[0392] Here, the oxide semiconductor film 336 is formed between the oxide semiconductor film 336a and the insulating film 312a. Therefore, the insulating film 312a is formed between the oxide semiconductor film 336b and the insulating film 312a. Even if carrier traps are formed by impurities and defects, the formation of the carrier traps As a result, there is a gap between the oxide semiconductor film 336a and the region where the oxide semiconductor Electrons flowing through the film 336a are less likely to be captured by carrier traps, and the on-current of the transistor It is possible to increase the field effect mobility. When an electron is captured in a carrier trap, the electron behaves as a negative fixed charge. However, the oxide semiconductor film 336 Because there is a gap between a and the region where carrier traps are formed, It is possible to reduce the trapping of electrons in the gate electrode, and thus to reduce the fluctuation of the threshold voltage. Cut.

[0393] In addition, the oxide semiconductor film 336b can block impurities from the outside. This can reduce the amount of impurities that move from the outside to the oxide semiconductor film 336a. In addition, oxygen vacancies are unlikely to be formed in the oxide semiconductor film 336b. It is possible to reduce the impurity concentration and oxygen vacancy in the film 336a.

[0394] Note that the oxide semiconductor film 336a and the oxide semiconductor film 336b are formed by simply stacking the respective films. Instead, it is a continuous junction (where the energy of the bottom of the conduction band changes continuously between the layers). In other words, the interface trap centers and recombination centers of each film are formed. The stacked structure is such that there are no impurities that would form defect levels. Impurities are present between the oxide semiconductor film 336a and the oxide semiconductor film 336b. When this happens, the continuity of the energy band is lost, and carriers are trapped or re-trapped at the interface. They combine and disappear.

[0395] To form continuous junctions, a multi-chamber deposition system equipped with a load lock chamber is required. Each film is laminated in succession using a sputtering device without being exposed to the atmosphere. Each chamber in the sputtering device is required for the oxide semiconductor film. In order to remove impurities such as water as much as possible, an adsorption type vacuum pump such as a cryopump is used. High vacuum pumping (5×10 -7 Pa~1×10 -4 It is preferable to Alternatively, a turbomolecular pump and a cold trap can be combined to separate the chamber from the exhaust system. It is preferable to prevent the backflow of gases, especially gases containing carbon or hydrogen, into the bar. stomach.

[0396] In FIG. 43, the multilayer film 336 is made up of an oxide semiconductor film 336a and an oxide semiconductor film 336b. However, an oxide semiconductor film 336b is formed between the insulating film 306 and the oxide semiconductor film 336a. Alternatively, a three-layer structure may be formed by providing a film similar to the insulating film 306b. The thickness of the oxide film provided between the oxide semiconductor film 336a and the oxide semiconductor film 336b is The thickness of the oxide film is preferably 1 nm or more and 5 nm or less, more preferably 1 nm or more and 3 nm or less. By making the thickness smaller than 1 nm, it is possible to reduce the amount of variation in the threshold voltage of the transistor. do.

[0397] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0398] (Embodiment 10) In this embodiment, a transistor included in the display device described in the above embodiment is In this regard, one embodiment applicable to an oxide semiconductor film and a metal oxide film will be described. The structure of the oxide semiconductor film described here can be applied to a metal oxide film as appropriate. <Structure of oxide semiconductors> The structure of an oxide semiconductor will be described below.

[0399] Oxide semiconductors are divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. As a non-single-crystal oxide semiconductor, CAAC-OS (C Axis Aligned Crystalline Oxide Semiconductor, polycrystalline oxide Examples of the oxide semiconductor include a semiconductor, a microcrystalline oxide semiconductor, and an amorphous oxide semiconductor.

[0400] From another point of view, oxide semiconductors are classified into amorphous oxide semiconductors and other crystalline oxides. Crystalline oxide semiconductors are divided into single-crystal oxide semiconductors, CAAC- Examples of such oxide semiconductors include OS, polycrystalline oxide semiconductors, and microcrystalline oxide semiconductors.

[0401] <caac-os> First, let me explain about CAAC-OS. Axis-Aligned Nanocrystals It can also be done as follows.

[0402] CAAC-OS is an oxide having multiple crystal parts (also called pellets) aligned along the c-axis. It is a type of semiconductor.

[0403] Transmission Electron Microscope (TEM) A combined analysis image (high resolution) of the bright-field image and diffraction pattern of CAAC-OS was obtained by using a microscope. When observing a high-resolution TEM image, multiple pellets can be confirmed. On the other hand, high-resolution TEM images reveal the boundaries between pellets, i.e., grain boundaries. Therefore, the CAAC-OS is not clearly characterized by the grain boundaries. It can be said that the resulting decrease in electron mobility is unlikely to occur.

[0404] Below, we will explain the CAAC-OS observed by TEM. 1 shows a high-resolution TEM image of a cross section of CAAC-OS observed from a direction approximately parallel to the sample surface. For high-resolution TEM imaging, spherical aberration correction is required. The spherical aberration correction function was used to obtain high-resolution TEM images. , specifically referred to as a Cs-corrected high-resolution TEM image. Cs-corrected high-resolution TEM images can be obtained, for example, This is performed using an atomic resolution analytical electron microscope such as the JEM-ARM200F manufactured by JEOL Ltd. It is possible.

[0405] An enlarged Cs-corrected high-resolution TEM image of area (1) in Figure 44(A) is shown in Figure 44(B). From Figure 44(B), it can be confirmed that the metal atoms are arranged in layers in the pellet. The arrangement of each metal atom layer is determined by the surface on which the CAAC-OS film is to be formed (also referred to as the surface on which the film is to be formed). Or it reflects the unevenness of the top surface and is parallel to the surface on which the CAAC-OS is formed or the top surface.

[0406] As shown in Figure 44(B), CAAC-OS has a characteristic atomic arrangement. ) shows the characteristic atomic arrangement with auxiliary lines. ) the size of each pellet is about 1 nm to 3 nm, and the size of each pellet is about 1 nm to 3 nm. It can be seen that the size of the gap caused by the tilt is about 0.8 nm. The pellets may also be referred to as nanocrystals (nc).

[0407] Here, based on the Cs-corrected high-resolution TEM image, the pellets of CAAC-OS on the substrate 5120 were The layout of the 5100 is shown diagrammatically as a stack of bricks or blocks. (See FIG. 44(D)). Between the pellets observed in FIG. 44(C), The portion where the tilt occurs corresponds to the area 5161 shown in FIG.

[0408] FIG. 45(A) shows the C of the plane of the CAAC-OS observed from a direction approximately perpendicular to the sample surface. s-corrected high-resolution TEM images are shown. Regions (1), (2) and (3) in Figure 45(A). ) are enlarged Cs-corrected high-resolution TEM images shown in Figure 45(B), Figure 45(C), and Figure 45(D), respectively. As shown in Figure 45(D), Figure 45(B), Figure 45(C) and Figure 45(D) show that the pellet It can be seen that the metal atoms are arranged in a triangular, quadrangular or hexagonal shape. However, no regularity is observed in the arrangement of metal atoms among different pellets.

[0409] Next, C analyzed by X-ray diffraction (XRD) For example, CAAC-O with InGaZnO4 crystals When S is subjected to structural analysis using the out-of-plane method, the result is as shown in Figure 46(A). As shown in the figure, a peak may appear at a diffraction angle (2θ) of around 31°. Since this is attributed to the (009) plane of the ZnO4 crystal, it is believed that the CAAC-OS crystal is c-axis oriented. It can be seen that the c-axis is oriented in a direction substantially perpendicular to the surface on which the film is formed or the upper surface.

[0410] In addition, in the structural analysis of CAAC-OS using the out-of-plane method, 2θ is 31 In addition to the peak around 2θ of 36°, a peak may also appear around 2θ of 36°. The peaks in the vicinity indicate that some of the CAAC-OS crystals do not have a c-axis orientation. The more preferable CAAC-OS is a structure produced by the out-of-plane method. The analysis shows a peak at 2θ around 31°, but no peak at 2θ around 36°.

[0411] On the other hand, in-pla, X-rays are incident on the CAAC-OS from a direction almost perpendicular to the c-axis. When structural analysis is performed using the NE method, a peak appears at 2θ around 56°. This peak is due to I It is attributed to the (110) plane of the nGaZnO4 crystal. In the case of CAAC-OS, 2θ is set to 5 The sample is fixed at approximately 6° and analyzed while rotating around the normal vector of the sample surface (φ axis). Even if a (φ scan) is performed, no clear peak appears as shown in Figure 46(B). On the other hand, in the case of a single crystal oxide semiconductor such as InGaZnO4, 2θ is fixed at around 56° and φ When scanned, it is assigned to a crystal plane equivalent to the (110) plane as shown in Figure 46(C). Six peaks are observed. Therefore, from the structural analysis using XRD, CAAC-OS It can be seen that the orientation of the a-axis and b-axis is irregular.

[0412] Next, we will explain the CAAC-OS analyzed by electron diffraction. For CAAC-OS with ZnO4 crystals, the probe diameter is 300 nm parallel to the sample surface. When an electron beam is incident on the sample, a diffraction pattern (selected area transmission electron diffraction) as shown in Figure 47(A) is generated. This diffraction pattern may appear due to the presence of InGaZnO4 This includes spots due to the (009) plane of the crystal. The pellets contained in the CAAC-OS have a c-axis orientation, and the c-axis faces the surface to be formed or the upper surface. On the other hand, when the probe was applied to the same sample perpendicular to the sample surface, The diffraction pattern when an electron beam with a diameter of 300 nm was incident is shown in Figure 47(B). 7(B), a ring-shaped diffraction pattern is confirmed. Therefore, electron diffraction It can be seen that the a-axis and b-axis of the pellets contained in CAAC-OS do not have any orientation. The first ring in FIG. 47(B) is the (010) plane of the InGaZnO4 crystal. This is thought to be due to the (100) plane and the like. This is thought to be due to the (110) surface.

[0413] In addition, the CAAC-OS is an oxide semiconductor with a low density of defect states. Defects include, for example, defects caused by impurities and oxygen vacancies. AC-OS can also be considered an oxide semiconductor with a low impurity concentration. S can also be said to be an oxide semiconductor with few oxygen vacancies.

[0414] Impurities contained in oxide semiconductors can act as carrier traps or as carrier generation sources. In addition, oxygen vacancies in an oxide semiconductor may become carrier traps or By capturing hydrogen, it may become a carrier generation source.

[0415] The impurities are elements other than the main components of the oxide semiconductor, such as hydrogen, carbon, silicon, and transition metals. For example, metal elements such as silicon are more oxidative than metal elements that constitute oxide semiconductors. Elements with strong bonding strength with the oxide semiconductor remove oxygen from the oxide semiconductor, which changes the atomic arrangement of the oxide semiconductor. In addition, heavy metals such as iron and nickel, argon, Carbon dioxide and other molecules have a large atomic radius (or molecular radius), so the atomic arrangement of oxide semiconductors This disrupts the structure and reduces the crystallinity.

[0416] In addition, oxide semiconductors with low defect state density (few oxygen vacancies) have low carrier density. Such an oxide semiconductor can be a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor. CAAC-OS has a low impurity concentration and a low density of defect states. Therefore, the oxide semiconductor is likely to be a highly pure intrinsic or substantially highly pure intrinsic oxide semiconductor. A transistor using AC-OS has electrical characteristics in which the threshold voltage is negative (normal It is also called "on." It is rare for it to become a high-purity intrinsic or substantially high-purity intrinsic Oxide semiconductors have few carrier traps. The charge that is trapped takes a long time to be released and behaves like a fixed charge. Therefore, transistors using oxide semiconductors with high impurity concentrations and high defect state densities are being developed. On the other hand, transistors using CAAC-OS can have unstable electrical characteristics. The resulting transistor has little fluctuation in electrical characteristics and is highly reliable.

[0417] In addition, CAAC-OS has a low defect level density, so it is possible to generate Therefore, the carriers are less likely to be captured by the defect level. The electrical characteristics of a transistor are less susceptible to change when irradiated with visible light or ultraviolet light.

[0418] <Microcrystalline oxide semiconductor> Next, a microcrystalline oxide semiconductor will be described.

[0419] Microcrystalline oxide semiconductors have regions where crystals can be confirmed in high-resolution TEM images. The microcrystalline oxide semiconductor has a crystal structure including a region where a crystal part is clearly visible and a region where a crystal part is not clearly visible. The crystal part contained is between 1 nm and 100 nm, or between 1 nm and 10 nm in size. In particular, fine crystals of 1 nm to 10 nm or 1 nm to 3 nm are often The oxide semiconductor with nanocrystalline structure is called nc-OS (nanocrystalline silicon). nc-OS is called NC-Oxide Semiconductor. In some cases, the grain boundaries cannot be clearly identified in the TEM images. It is possible that the origin of the pellets in C-OS is the same as that of the pellets in C-OS. The crystalline part of the OS is sometimes called a pellet.

[0420] nc-OS is a material that can be used in microscopic areas (e.g., areas between 1 nm and 10 nm, especially areas between 1 nm and 10 nm). The atomic arrangement is periodic in the region of 3 nm or less. There is no regularity in the crystal orientation between the layers. Therefore, no orientation is observed throughout the film. Therefore, depending on the analysis method, nc-OS may be indistinguishable from amorphous oxide semiconductors. For example, an XRD apparatus using an X-ray beam with a diameter larger than that of the pellet is used for nc-OS. When structural analysis is performed using the out-of-plane method, the crystal plane is shown. In addition, the probe diameter ( For example, electron diffraction (also called selected area electron diffraction) is performed using an electron beam of 50 nm or more. On the other hand, for nc-OS, a halo-like diffraction pattern is observed. Nanobeam electron circuits use electron beams with a probe diameter close to the pellet size or smaller than the pellet. When the nc-OS is subjected to nanobeam electron diffraction, spots are observed. When the light is too bright, a circular (ring-shaped) area of ​​high brightness may be observed. Multiple spots may be observed within a ring-like region.

[0421] In this way, the crystal orientation between the pellets (nanocrystals) is not regular, so nc -OS with RANC (Random Aligned nanocrystals) oxide semiconductors, or NANCs (Non-Aligned Nanocrystals) The semiconductor may also be referred to as an oxide semiconductor having a structure (s).

[0422] The nc-OS is an oxide semiconductor with higher order than an amorphous oxide semiconductor. However, the density of defect states in nc-OS is lower than that in amorphous oxide semiconductors. There is no regularity in the crystal orientation between different pellets in S. Therefore, nc-OS is The defect density is higher than that of AAC-OS.

[0423] <Amorphous oxide semiconductor> Next, the amorphous oxide semiconductor will be described.

[0424] Amorphous oxide semiconductors are oxides in which the atomic arrangement within the film is irregular and does not have crystalline parts. An example is an oxide semiconductor that has an amorphous state, such as quartz.

[0425] In amorphous oxide semiconductors, no crystalline parts can be observed in high-resolution TEM images.

[0426] When structural analysis is performed on amorphous oxide semiconductors using an XRD device, out-of-p In the analysis by the Lane method, no peaks indicating crystal planes were detected. When electron diffraction is performed on a conductor, a halo pattern is observed. When nanobeam electron diffraction is performed on the sample, no spots are observed, and only a halo pattern is observed. It is observed.

[0427] There are various views on amorphous structures. For example, A structure that does not have this property is called a completely amorphous structure. The distance between the nearest neighboring atoms or the second nearest neighboring atoms is also called the structure. A structure that has order at the interface but does not have long-range order is sometimes called an amorphous structure. Therefore, according to the strictest definition, an oxide semiconductor that has even a slight degree of order in its atomic arrangement is called a non-metallic oxide semiconductor. Furthermore, it cannot be called an crystalline oxide semiconductor. Therefore, since the semiconductor has crystalline parts, it cannot be called an amorphous oxide semiconductor. For example, CAAC-OS and nc-OS are used as amorphous oxide semiconductors or completely amorphous It cannot be called an oxide semiconductor.

[0428] <Amorphous-like oxide semiconductor> Note that an oxide semiconductor may have a structure between an nc-OS and an amorphous oxide semiconductor. An oxide semiconductor having such a structure is particularly called an amorphous-like oxide semiconductor (aluminum oxide). ike OS:amorphous-like Oxide Semiconducto It is called r).

[0429] In a-like OS, voids (also called voids) are observed in high-resolution TEM images. In addition, crystals can be clearly seen in high-resolution TEM images. and regions where no crystalline portions can be identified.

[0430] Because of the porosity, the a-like OS has an unstable structure. e OS has an unstable structure compared with CAAC-OS and nc-OS. This shows the structural changes caused by electron irradiation.

[0431] The samples to be irradiated with electrons were a-like OS (referred to as sample A), nc-OS (hereinafter referred to as Sample B) and CAAC-OS (hereinafter referred to as Sample C) are prepared. Both samples are In-Ga-Zn oxides.

[0432] First, high-resolution cross-sectional TEM images of each sample are acquired. It can be seen that all the materials have crystalline parts.

[0433] The determination of which part is to be regarded as one crystal part can be made as follows. For example, The unit cell of the InGaZnO4 crystal has three In-O layers and one Ga-Zn-O layer. It is known that the structure has a total of nine layers, six of which are stacked in layers in the c-axis direction. The spacing between these adjacent layers is approximately the same as the lattice spacing (also called the d value) of the (009) plane. The value is calculated to be 0.29 nm from crystal structure analysis. The areas where the spacing is 0.28 nm or more and 0.30 nm or less are considered to be InGaZnO4 crystal parts. The lattice fringes correspond to the ab plane of the InGaZnO4 crystal.

[0434] Figure 48 shows an example of investigating the average size of the crystal parts (22 to 45 locations) of each sample. However, the length of the lattice fringes mentioned above is the size of the crystal part. It can be seen that the crystalline part of ke OS grows in size according to the cumulative amount of electron irradiation. Specifically, as shown in Figure 48 (1), the initial TEM observation showed a size of about 1.2 nm. The crystal part (also called the initial nucleus) was 4.2 × 10 8 e - / n m 2 On the other hand, in the nc-O For S and CAAC-OS, the cumulative electron irradiation dose from the start of electron irradiation was 4.2 × 10 8 e - / nm 2 It can be seen that there is no change in the size of the crystal part within the range of As shown in (2) and (3) in Figure 48, regardless of the cumulative electron dose, the nc-OS and The sizes of the crystal parts of the CAAC-OS and CAAC-OS are approximately 1.4 nm and 2.1 nm, respectively. It can be seen that...

[0435] In this way, the growth of crystalline parts can be observed in a-like OS due to electron irradiation. On the other hand, in nc-OS and CAAC-OS, the growth of the crystals by electron irradiation is almost nonexistent. In other words, a-like OS is not as good as nc-OS and CAAC- It is clear that it has an unstable structure compared to the OS.

[0436] In addition, due to its porosity, a-like OS is more flexible than nc-OS and CAAC-OS. Specifically, the density of a-like OS is lower than that of a single crystal of the same composition. The density of the nc-OS is 78.6% or more and less than 92.3% of that of the normal crystal. The density of C-OS is 92.3% or more but less than 100% of the density of a single crystal of the same composition. It is difficult to form a film of an oxide semiconductor having a crystal density of less than 78%.

[0437] For example, in an oxide semiconductor having an atomic ratio of In:Ga:Zn=1:1:1, The density of single-crystal InGaZnO4 with a rhombohedral crystal structure is 6.357 g / cm 3 It becomes. For example, in an oxide semiconductor that satisfies the atomic ratio of In:Ga:Zn=1:1:1, The density of a-like OS is 5.0 g / cm 3 More than 5.9g / cm 3 It will be less than For example, in an oxide semiconductor having an atomic ratio of In:Ga:Zn=1:1:1, , the density of nc-OS and the density of CAAC-OS are 5.9 g / cm 3 More than 6.3g / cm 3 It will be less than.

[0438] In some cases, single crystals with the same composition do not exist. In such cases, crystals with different compositions may be used in any proportion. By combining single crystals with the desired composition, the density equivalent to that of a single crystal can be estimated. The density corresponding to a single crystal of a desired composition can be obtained by combining single crystals of different compositions. The density should be as low as possible. It is preferable to estimate by combining different types of single crystals.

[0439] As described above, oxide semiconductors have various structures, each of which has various characteristics. The oxide semiconductor may be, for example, an amorphous oxide semiconductor, an a-like OS, or a microcrystalline oxide semiconductor. The layer may be a laminated film containing two or more of a compound semiconductor and a CAAC-OS.

[0440] <Film formation model> An example of a film formation model for CAAC-OS and nc-OS will be described below.

[0441] FIG. 49(A) shows a process of forming a CAAC-OS film by sputtering. Schematic diagram of the inside of the membrane chamber.

[0442] The target 5130 is glued to a backing plate. A plurality of magnets are arranged at positions facing the target 5130 through the magnets. The magnetic field is generated by a number of magnets. The sputtering method used is called magnetron sputtering.

[0443] The substrate 5120 is disposed so as to face the target 5130, and the distance therebetween is d( The target-substrate distance (also called the TS distance) is preferably 0.01 m or more and 1 m or less. The thickness of the film deposition chamber is 0.02m or more and 0.5m or less. oxygen, argon, or a gas mixture containing 5% or more by volume of oxygen) and The pressure is controlled to 1 Pa or more and 100 Pa or less, preferably 0.1 Pa or more and 10 Pa or less. By applying a voltage above a certain level to the target 5130, a discharge begins and plasma is generated. It is confirmed that a high density plasma region is generated near the target 5130 by the magnetic field. In the high density plasma region, the deposition gas is ionized, and ions 5101 The ions 5101 are, for example, positive ions of oxygen (O + ) and argon cations ( Ar + ) etc.

[0444] Here, the target 5130 has a polycrystalline structure having a plurality of crystal grains, and The crystal grains include cleavage planes. The crystal structure of InGaZnO4 is shown in Fig. 50(A). This is the structure of InGaZnO4 crystals observed from the side. In the two Ga-Zn-O layers, the oxygen atoms in each layer are arranged in close proximity. The negative charge of the oxygen atom makes it possible to separate two adjacent atoms. Repulsion occurs between the Ga-Zn-O layers. As a result, the InGaZnO4 crystals are The cleavage plane is located between the two Ga-Zn-O layers.

[0445] Ions 5101 generated in the high-density plasma region are attracted to the target 5130 by the electric field. The particles are accelerated and eventually collide with the target 5130. At this time, flat or planar particles are formed from the cleavage plane. pellets 5100a and 5100b, which are pellet-shaped sputtered particles, are peeled off, The pellets 5100a and 5100b are ejected by the ions 5101. The impact of a collision can cause distortion of the structure.

[0446] The pellet 5100a is a flat plate or pellet having a triangular, for example, equilateral triangular, plane. The pellet 5100b is a sputtered particle having a hexagonal shape, for example, a regular hexagonal plane. The pellets 5100a and 5100b are sputtered particles in the form of plates or pellets. Sputter particles in the form of flat or pellets, such as pellets 5100b, are collectively called pellets. The planar shape of the pellet 5100 is not limited to a triangle or a hexagon, for example. For example, there are cases where the shape is made up of multiple triangles. In some cases, two squares (or polygons) may join together to form a quadrilateral (for example, a rhombus).

[0447] The thickness of the pellet 5100 is determined depending on the type of deposition gas, etc. The reason for this will be explained later. It is preferable that the thickness of the pellet 5100 is uniform. Thin pellets are preferable to thick cubes. The thickness of the PET 5100 is 0.4 nm or more and 1 nm or less, preferably 0.6 nm or more and 0.8 nm or less. For example, the pellet 5100 has a width of 1 nm or more and 3 nm or less, preferably The pellet 5100 is the one shown in FIG. ) corresponds to the initial nucleus described in (1). For example, the target 5 having In-Ga-Zn oxide When ions 5101 are bombarded onto the Ga-Zn-O layer 130, as shown in FIG. 50(B), A pellet 5100 having three layers, an In-O layer, and a Ga-Zn-O layer, is exfoliated. Fig. 0(C) shows the structure of the exfoliated pellet 5100 observed from a direction parallel to the c-axis. The RET 5100 is a nano-sized wafer with two Ga-Zn-O layers and an In-O layer. It can also be called a sandwich structure.

[0448] As the pellet 5100 passes through the plasma, the sides may become negatively or positively charged. The pellet 5100 may have negatively charged oxygen atoms located on its sides, for example. The sides have charges of the same polarity, which causes repulsion between the charges, resulting in a flat or penetrating shape. It is possible to maintain the shape of the In-Ga-Z In the case of n-oxide, the oxygen atom bonded to the indium atom may be negatively charged. Or, an oxygen atom bonded to an indium atom, a gallium atom, or a zinc atom is negatively charged. In addition, when the pellet 5100 passes through the plasma, it may The area where it grows by bonding with indium atoms, gallium atoms, zinc atoms, oxygen atoms, etc. The difference in size between (2) and (1) in Figure 48 above is due to the growth in the plasma. Here, when the substrate 5120 is at room temperature, the pellets on the substrate 5120 The growth of 5100 is difficult to occur, resulting in nc-OS (see Figure 49(B)). Since the film can be formed at a low temperature, nc-OS can be formed even on a large substrate (5120). In order to grow the pellet 5100 in plasma, the sputtering method is used. Increasing the film formation power in the pellet 5 is effective. 100 structures can be stabilized.

[0449] As shown in Figures 49(A) and 49(B), for example, the pellet 5100 is a plasma It flies like a kite through the air and flutters up to the top of the board 5120. Since the pellet 100 is electrically charged, it will be attracted to an area where other pellets 5100 are already deposited. Here, on the upper surface of the substrate 5120, a repulsive force is generated in a direction parallel to the upper surface of the substrate 5120. A horizontal magnetic field (also called a horizontal magnetic field) is generated between the substrate 5120 and the target 5120. Since a potential difference is applied between the substrate 5120 and the target 5130, Therefore, the pellet 5100 is disposed on the upper surface of the substrate 5120 in the following direction: The magnetic field and the electric current act on the object, creating a force (Lorentz force). This can be understood by the left-hand rule.

[0450] The pellet 5100 has a larger mass than an atom. In order to move the surface, it is important to apply some kind of force from the outside. One of these forces is It is possible that the force is generated by the action of a magnetic field and an electric current. To provide sufficient force to move the top surface of 5120, the top surface of substrate 5120 must: The magnetic field parallel to the upper surface of the substrate 5120 is 10 G or more, preferably 20 G or more, and more preferably It is preferable to provide a region where the resistance is 30 G or more, and more preferably 50 G or more. On the upper surface of the plate 5120, a magnetic field parallel to the upper surface of the substrate 5120 The magnetic field is 1.5 times or more, preferably 2 times or more, and more preferably 3 times or more than the magnetic field perpendicular to the upper surface. It is preferable to provide an area where the thickness is 5 times or more, more preferably 5 times or more.

[0451] At this time, the magnet and the substrate 5120 move or rotate relative to each other. The direction of the horizontal magnetic field on the upper surface of the substrate 5120 continues to change. On the upper surface of the plate 5120, the pellet 5100 is subjected to forces from various directions. You can move to.

[0452] Also, when the substrate 5120 is heated as shown in FIG. 49(A), the pellet 510 0 and the substrate 5120, the resistance due to friction etc. is small. The pellet 5100 glides over the top surface of the substrate 5120. The transfer occurs with the flat surface facing the substrate 5120. When the particles reach the side of the pellet 5100, the sides are joined together. The oxygen atom on the side of 00 is released. The released oxygen atom causes the Since oxygen vacancies may be filled, a CAAC-OS with a low density of defect states is obtained. The temperature of the upper surface of the plate 5120 is, for example, 100°C or higher and lower than 500°C, or 150°C or higher and 450°C. or 170° C. or higher and lower than 400° C. Even in such a case, it is possible to form a CAAC-OS film.

[0453] In addition, the pellet 5100 is heated on the substrate 5120, whereby the atoms are rearranged. The distortion of the structure caused by the collision of the ions 5101 is relaxed. 100 is almost a single crystal. Pellet 5100 is almost a single crystal. Even if the pellets 5100 are heated after being bonded together, the pellets 5100 themselves do not expand. Therefore, the gaps between the pellets 5100 widen, and the crystallization Defects such as grain boundaries do not form, and crevasses do not form.

[0454] In addition, the CAAC-OS is not made of a single-crystal oxide semiconductor. The aggregates of pellets 5100 (nanocrystals) resemble bricks or blocks stacked on top of each other. In addition, there are no grain boundaries between the pellets 5100. Heating during film formation, heating after film formation, or bending can cause deformation such as shrinkage in CAAC-OS. Even in such a case, it is possible to relieve local stress or release strain. This structure is suitable for use in flexible semiconductor devices. The resulting arrangement is like a disorderly stack of Red 5100 (nanocrystals).

[0455] When the target 5130 is sputtered by the ions 5101, not only the pellet 5100 but also Zinc oxide is lighter than pellet 5100. Therefore, it reaches the upper surface of the substrate 5120 first. A zinc oxide layer 5102 having a thickness of 2 nm or more and 5 nm or less, or 0.5 nm or more and 2 nm or less, is formed. Figure 51 shows a schematic cross-sectional view.

[0456] As shown in FIG. 51(A), a pellet 5105a and a pellet Here, the pellets 5105a and 5105b are deposited. The pellets 5105c are arranged so that their sides are in contact with each other. After being deposited on pellet 5105b, the pellet 510 slides on pellet 5105b. In another aspect of FIG. 5a, a plurality of particles 510 detached from the target along with zinc oxide. 3 is crystallized by heating from the substrate 5120 to form a region 5105a1. The number of particles 5103 may include oxygen, zinc, indium, and gallium, among others.

[0457] As shown in FIG. 51(B), the region 5105a1 is integral with the pellet 5105a. The pellet 5105c is formed by the side surface of the pellet 5105a. Place it so that it is in contact with another side of 5105b.

[0458] Next, as shown in FIG. 51(C), a pellet 5105d is further added to the pellet 5105a2. After being deposited on pellet 5105a2 and pellet 5105b, It slides on the other side of the pellet 5105c. The pellet 5105e slides on the zinc oxide layer 5102.

[0459] As shown in FIG. 51(D), the pellet 5105d has a side surface similar to that of the pellet 51. The pellet 5105e is placed so that its side faces the pellet 5105a2. Also, the other side of the pellet 5105d is placed in contact with the other side of the pellet 5105c. On the surface, a plurality of particles 5103 peeled off from the target 5130 together with zinc oxide are formed. Heating plate 5120 causes it to crystallize, forming region 5105d1.

[0460] As described above, the piled pellets are arranged so that they come into contact with each other, and the side surfaces of the pellets are Crystal growth occurs, forming a CAAC-OS on the substrate 5120. CAAC-OS has larger individual pellets than nc-OS. The difference in size between (3) and (2) corresponds to the growth after deposition.

[0461] In addition, the gaps between the pellets become extremely small, forming one large pellet. One large pellet may have a single crystal structure. The size is 10 nm or more and 200 nm or less, 15 nm or more and 100 nm or less when viewed from the top surface, or In this case, the size of the transistors used can be between 20 nm and 50 nm. In an oxide semiconductor, a channel formation region may be contained in one large pellet. That is, a region having a single crystal structure can be used as a channel forming region. As the size of the lattice increases, the region with a single crystal structure becomes the channel formation region of the transistor. , may be used as source and drain regions.

[0462] In this way, the channel formation region of the transistor and the like are formed in a region having a single crystal structure. By doing so, it may be possible to improve the frequency characteristics of the transistor.

[0463] Based on the above model, it is assumed that the pellet 5100 is deposited on the substrate 5120. CAAC-OS can be deposited even when the surface does not have a crystalline structure. This indicates that the growth mechanism is different from epitaxial growth. AC-OS does not require laser crystallization and can be grown uniformly even on large glass substrates. For example, if the structure of the upper surface (surface to be formed) of the substrate 5120 is an amorphous structure (e.g., It is possible to form a CAAC-OS film even on amorphous silicon oxide.

[0464] In addition, even if the upper surface of the substrate 5120 on which the formation is performed is uneven, the CAAC-OS It can be seen that the pellets 5100 are arranged along the shape of the substrate 5120. If the surface is atomically flat, the pellet 5100 will have a flat surface that is parallel to the ab plane. If the thickness of the pellet 5100 is uniform, it is flat and has a uniform thickness. A layer with high crystallinity is formed. Then, the layer is stacked in n layers (n is a natural number). By doing so, CAAC-OS can be obtained.

[0465] On the other hand, even if the upper surface of the substrate 5120 has irregularities, the CAAC-OS can be easily formed by the pellet 51 The structure is made up of n layers (n is a natural number) of layers in which 00 are arranged along the unevenness. Because the surface of the CAAC-OS is uneven, gaps tend to form between the pellets. However, even in this case, intermolecular forces act between the pellets 5100, and unevenness may occur. Even if the pellets are uneven, they are arranged so that the gaps between them are as small as possible. Furthermore, a CAAC-OS having high crystallinity can be obtained.

[0466] Since the CAAC-OS film is formed using this model, the sputtered particles are distributed evenly across the film thickness. It is preferable that the sputtered particles are in the form of thick dices. In this case, the surface facing the substrate 5120 is not uniform, and the thickness and crystal orientation cannot be made uniform. There is.

[0467] The film formation model shown above allows for highly crystalline films to be formed even on a surface with an amorphous structure. Therefore, a CAAC-OS having the desired properties can be obtained.

[0468] <cleavage plane> Below, we explain the cleavage plane of the target described in the CAAC-OS film formation model. Reveal.

[0469] First, the cleavage plane of the target will be explained using Figure 52. Figure 52 shows the cleavage plane of InGaZ The crystal structure of nO4 is shown in Figure 52(A). The c-axis is oriented upward and parallel to the b-axis. The structure of the InGaZnO4 crystal is shown when observed from the direction of the crystal. This shows the structure of an InGaZnO4 crystal when observed from a direction parallel to the axis.

[0470] The energy required for cleavage on each crystal plane of InGaZnO4 crystal was calculated using first-principles calculations. The calculation is performed using a pseudopotential and a density functional function using a plane wave basis. The pseudopotential used is an ultra-soft pseudopotential. The potential is used. The functional is GGA PBE. The cutoff The energy is set to 400 eV.

[0471] The energy of the structure in the initial state was derived after structural optimization including the cell size. In addition, the energy of the structure after cleavage on each plane is calculated by the atomic ratio with the cell size fixed. It is derived after structural optimization of the arrangement.

[0472] Based on the crystal structure of InGaZnO4 shown in Figure 52, the first plane, second plane, and third plane A structure cleaved at either the first or fourth plane was fabricated, and structural optimization calculations were performed with the cell size fixed. Here, the first plane is a crystal plane between the Ga-Zn-O layer and the In-O layer, and ( The second plane is a crystal plane parallel to the (001) plane (or ab plane) (see Figure 52(A)). , the crystal plane between the Ga-Zn-O layer and the Ga-Zn-O layer, and the (001) plane (or a The third plane is a crystal plane parallel to the (110) plane (see Figure 52(A)). The fourth plane is the (100) plane (or bc plane) (see Figure 52(B)). The crystal planes are parallel (see Figure 52(B)).

[0473] Under the above conditions, the energy of the structure after cleavage on each plane is calculated. Divide the difference between the energy of the structure and the energy of the structure in its initial state by the area of ​​the cleavage plane. The cleavage energy, which is a measure of the ease of cleavage on each plane, is calculated. The energy is the kinetic energy of the electrons and the interatomic and atomic energy for the atoms and electrons contained in the structure. This is the energy that takes into account interactions between electrons and between electrons.

[0474] As a result of calculations, the cleavage energy of the first facet is 2.60 J / m 2 , the cleavage energy of the second face -0.68J / m 2 , the cleavage energy of the third face is 2.18 J / m 2 , cleavage of the fourth plane Energy is 2.12J / m 2 It was found that (see table below).

[0475] [Table 1]

[0476] From this calculation, in the crystal structure of InGaZnO4 shown in Figure 52, The cleavage energy is lowest at the Ga-Zn-O layer and the Ga-Zn-O layer. It can be seen that the plane between the two is the plane (cleavage plane) that is easiest to cleave. When the term "cleavage plane" is used, it refers to the second plane, which is the plane that is easiest to cleave.

[0477] Since the cleavage plane is on the second plane between the Ga-Zn-O layers, The InGaZnO4 crystal shown in 52(A) is separated by a plane equivalent to the two second planes. Therefore, when ions or the like are bombarded with the target, the highest cleavage energy is obtained. The wafer-like units (we call them pellets) cleaved from the lower surface of the ghee are the best. In this case, the InGaZnO4 pellets The resulting layer is a Ga-Zn-O layer, an In-O layer, and a Ga-Zn-O layer.

[0478] The first plane (a crystal plane between the Ga-Zn-O layer and the In-O layer, which is the (001) plane) (or ab plane)), the third plane (a crystal plane parallel to the (110) plane), The cleavage energy of the fourth plane (a crystal plane parallel to the (100) plane (or bc plane)) is low. This suggests that the planar shape of the pellets is often triangular or hexagonal.

[0479] Next, classical molecular dynamics calculations were performed to identify the target InGa Assuming a ZnO4 crystal, the target is sintered with argon (Ar) or oxygen (O). The cleavage plane of the InGaZnO4 crystal (26 The cross-sectional structure of the 88 atoms is shown in Figure 53(A), and the top view structure is shown in Figure 53(B). The fixed layer shown in (A) is a layer in which the atomic arrangement is fixed so that the position does not fluctuate. The temperature control layer shown in 53(A) is a layer that is always kept at a constant temperature (300K).

[0480] For classical molecular dynamics calculations, Fujitsu Materials Explorer 5 was used. .0 is used. The initial temperature is 300K, the cell size is constant, and the time step width is 0.01f. The calculation assumes that the number of steps is 10 million femtoseconds. eV of energy is applied, and atoms are introduced into the cell from a direction perpendicular to the ab plane of the InGaZnO4 crystal. is incident.

[0481] FIG. 54(A) shows the state in which argon is introduced into the cell having the InGaZnO4 crystal shown in FIG. Figure 54(B) shows the atomic arrangement 99.9 picoseconds (psec) after irradiation. The atomic arrangement shown in Figure 54 is 99.9 picoseconds after oxygen is incident on the electron beam. A part of the fixed layer shown in (A) is omitted.

[0482] From Figure 54(A), within 99.9 picoseconds after argon entered the cell, ) the cracks occur from the cleavage plane corresponding to the second plane shown in Fig. 1. Therefore, InGaZnO4 When argon collides with the crystal, if the top surface is the second surface (0th), It can be seen that a large crack occurs in the second

[0483] On the other hand, from Figure 54(B), within 99.9 picoseconds after oxygen entered the cell, the It can be seen that cracks occur from the cleavage plane corresponding to the second plane shown in A). In the event of a collision, a large crack will occur on the second (first) surface of the InGaZnO4 crystal. You can see that this is happening.

[0484] Therefore, the top surface of the target containing InGaZnO4 crystals with a homologous structure When atoms (ions) collide from the surface, the InGaZnO4 crystal cleaves along the second plane, It can be seen that flat particles (pellets) are peeled off. At this time, the size of the pellets It was found that the collision with oxygen was smaller than that with argon. Light.

[0485] The above calculations suggest that the detached pellet contains a damaged area. Damaged regions in the matrix can be repaired by reacting oxygen with the defects caused by the damage. There are cases where this happens.

[0486] Therefore, we investigated whether the pellet size differs depending on the atom that is collided. do.

[0487] In FIG. 55(A), argon is introduced into the cell having the InGaZnO4 crystal shown in FIG. The trajectory of each atom is shown from 0 picoseconds to 0.3 picoseconds after irradiation. 55(A) corresponds to the period between FIG. 53 and FIG. 54(A).

[0488] As shown in Figure 55(A), argon collides with gallium (Ga) in the first layer (Ga-Zn-O layer). Then, after the gallium collides with the zinc (Zn) in the third layer (Ga-Zn-O layer), It can be seen that zinc reaches the vicinity of the sixth layer (Ga-Zn-O layer). The colliding argon is repelled outwards. Therefore, the crystals containing InGaZnO4 When argon is bombarded onto the target, a turtle appears on the second surface (second) in Figure 53(A). It is thought that cracks will occur.

[0489] Also, in FIG. 55(B), oxygen is added to the cell having the InGaZnO4 crystal shown in FIG. The trajectory of each atom from 0 picoseconds to 0.3 picoseconds after injection is shown. Therefore, FIG. 55(B) corresponds to the period between FIG. 53 and FIG. 54(A).

[0490] On the other hand, as shown in Figure 55(B), oxygen collides with gallium (Ga) in the first layer (Ga-Zn-O layer). When the gallium collides with the zinc (Zn) in the third layer (Ga-Zn-O layer), It can be seen that the zinc does not reach the fifth layer (In-O layer). Oxygen is expelled outwards. Therefore, for a target containing InGaZnO4 crystals, When oxygen is bombarded, it is thought that cracks will appear on the second surface (first surface) in Figure 53(A). can be.

[0491] This calculation also shows that when atoms (ions) collide with InGaZnO4 crystals, the cleavage plane It is suggested that the tissue peels off.

[0492] In addition, we consider the difference in crack depth from the viewpoint of conservation laws. The conservation laws can be expressed as equations (1) and (2), where E is the a The energy of argon or oxygen (300 eV), m A is the mass of argon or oxygen, v A is the velocity of argon or oxygen before collision, v' A is the velocity of argon or oxygen after the collision , m Ga is the mass of gallium, v Ga is the velocity of gallium before the collision, v' Ga is the gully after the collision It's the speed of Um.

[0493]

number

[0494]

number

[0495] Assuming that the collisions of argon or oxygen are elastic, v A , v' A , v Ga Oh ビv' Ga The relationship can be expressed as equation (3).

[0496]

number

[0497] From equations (1), (2) and (3), v Ga If argon or oxygen is The velocity of the gallium after the collision is v' Ga can be expressed as in equation (4).

[0498]

number

[0499] In equation (4), m A Substitute the mass of argon or the mass of oxygen into Compare the velocity of gallium after the collision with argon and oxygen. When the number of atoms is the same, the collision with argon is 1.2 times greater than the collision with oxygen. It can be seen that the speed of gallium is four times higher. Therefore, the energy possessed by gallium is also When Gon collides, the velocity is squared higher than when oxygen collides.

[0500] When argon is bombarded, the gallium after the bombardment is more dense than when oxygen is bombarded. Therefore, when argon is collided, It is thought that cracks occurred at deeper positions in the case of oxygen bombardment than in the case of oxygen bombardment.

[0501] From the above calculations, it is possible to obtain a target containing InGaZnO4 crystals with a homologous structure. When sputtered, it peels off from the cleaved surface and forms a pellet. Sputtering other structural areas of the target that do not have a surface does not form pellets. The sputtered particles are formed at the atomic level, which are smaller than the particles. Because it is smaller than a pellet, it can be easily removed by a vacuum pump connected to the sputtering device. Therefore, the crystal structure of InGaZnO4 with homologous structure When a target containing argon is sputtered, particles of various sizes and shapes fly to the substrate and accumulate. It is difficult to imagine a model in which a film is formed by deposition of sputtered pellets. The model shown in Figure 49(A) for forming a C-OS film is reasonable.

[0502] The density of the CAAC-OS film formed in this way is comparable to that of single-crystal OS. For example, the density of a single crystal OS with a homologous structure of InGaZnO4 is 6.36g. / cm 3 In contrast, the density of CAAC-OS, which has a similar atomic ratio, is 6.3 g / cm m 3 It will be about that amount.

[0503] Figure 56 shows the In-Ga-Zn oxide (CAAC-OS) film formed by sputtering. (See Figure 56(A)) and the cross section of the target (See Figure 56(B)). The atomic arrangement is shown. The atomic arrangement was observed using high-angle annular dark-field scanning transmission electron microscopy (HAEC). ADF-STEM:High-Angle Annular Dark Field S canning Transmission Electron Microscopy In HAADF-STEM, the image intensity of each atom is proportional to the square of the atomic number. Therefore, Zn (atomic number 30) and Ga (atomic number 31) have similar atomic numbers. The HAADF-STEM uses a Hitachi HD-27 scanning transmission electron microscope. Use 00.

[0504] Comparing Figure 56(A) and Figure 56(B), the CAAC-OS and the target are Both have homologous structures, and it can be seen that the arrangement of their atoms corresponds to each other. Therefore, as shown in the film formation model in Figure 49(A), the crystal structure of the target is transformed. The image shows that a CAAC-OS film has been formed.

[0505] <Oxide Semiconductor Films and Metal Oxide Films> An oxide semiconductor film such as the oxide semiconductor film 308b shown in FIG. 1 used in a transistor and a film formed of a silicon dioxide film (hereinafter referred to as an oxide semiconductor film (OS)) and a film used as an electrode of a capacitor. A film formed of an oxide conductor, such as the metal oxide film 308c shown in FIG. The temperature dependence of resistivity in each of these films is as follows: This will be explained using Figure 57. In Figure 57, the horizontal axis shows the measured temperature, and the vertical axis shows the resistivity. The measurement results for the oxide semiconductor film (OS) are indicated by a circle, and the measurement results for the oxide conductor film (OC) are indicated by a circle. The measured results are indicated by squares.

[0506] The sample including the oxide semiconductor film (OS) was formed on a glass substrate with an atomic ratio of In:Ga Zn=1:1:1.2 sputtering target. An In-Ga-Zn oxide film with a thickness of 35 nm was formed, and the atomic ratio was In:Ga:Zn=1:4. :5 sputtering target was used to deposit a 20 nm thick In- A Ga-Zn oxide film was formed, and after heat treatment in a nitrogen atmosphere at 450°C, and heat treatment in a mixed gas atmosphere of silicon and oxygen, and then a silicon oxynitride film is formed by plasma CVD. was formed and produced.

[0507] The sample containing the oxide conductor (OC) film was formed on a glass substrate with an atomic ratio of In:Ga. Zn=1:1:1 sputtering target was used to deposit a 10 ... After forming a 00 nm In-Ga-Zn oxide film and heat-treating it in a nitrogen atmosphere at 450°C, The silicon nitride film was then heated at 450°C in a mixed gas atmosphere of nitrogen and oxygen, and then deposited by plasma CVD. It was prepared by forming a com film.

[0508] As can be seen from Figure 57, the temperature dependence of resistivity in the oxide conductor film (OC) is The temperature dependence of resistivity is smaller than that of oxide semiconductor films (OS). Typically, it is 80K or higher. The resistivity change rate of the oxide conductor film (OC) at 290K or less is less than ±20% Alternatively, the rate of change in resistivity between 150K and 250K is less than ±10%. That is, an oxide conductor is a degenerate semiconductor, and the conduction band edge and the Fermi level are coincident or approximately coincident. Therefore, it is considered that the oxide conductor film is used for the resistance element, wiring, and capacitance element. It can be used for electrodes, pixel electrodes, common electrodes, etc.

[0509] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0510] (Embodiment 11) As described in Embodiment 2, a transistor including an oxide semiconductor film has a low resistance in an off state. Therefore, the current value (off-state current value) in the The retention time can be extended, and the write interval can also be set longer.

[0511] In the liquid crystal display device of this embodiment, a transistor with a low off-state current is used, The liquid crystal display device can be configured to perform display using at least two driving methods (modes). The driving mode is a conventional method for driving a liquid crystal display device, in which data is sequentially transferred for each frame. The second driving mode is a driving method in which, after the data writing process is performed, This is a driving method that stops rewriting of data. In other words, the refresh rate is reduced. This is the driving mode.

[0512] The first driving mode is used to display moving images. The second driving mode is used to display still images. Since the image data remains unchanged, there is no need to rewrite the data for each frame. When displaying still images, the second driving mode eliminates screen flicker. At the same time, power consumption can be reduced.

[0513] Furthermore, the liquid crystal element applied to the liquid crystal display device of this embodiment is a capacitance element having a large area. Therefore, the time to hold the potential of the pixel electrode is It is possible to lengthen the display, and a driving mode that reduces the refresh rate can be applied. Furthermore, when a driving mode that reduces the refresh rate is applied to a liquid crystal display device, Even if the voltage applied to the liquid crystal layer changes, it is possible to suppress the change for a long period of time. This can further prevent the perception of image flicker by the viewer. This makes it possible to improve the display quality.

[0514] Here, the effect of reducing the refresh rate will be described.

[0515] There are two types of eye fatigue: nervous fatigue and muscular fatigue. By continuing to look at the luminous or flashing screen of an LCD display, the brightness can damage the retina, nerves, and brain. Fatigue in the muscular system stimulates and tires the ciliary muscles used for focusing. It fatigues the muscles by overworking them.

[0516] FIG. 58(A) is a schematic diagram showing the display of a conventional liquid crystal display device. As shown above, the image displayed on a conventional LCD display is rewritten 60 times per second. Looking at such a screen for a long time can stimulate the retina, nerves, and brain of the user. This could cause eye fatigue.

[0517] In one embodiment of the present invention, a pixel portion of a liquid crystal display device includes a transistor with extremely low off-state current, For example, a transistor including an oxide semiconductor is used. This prevents leakage of electric charge stored in the capacitor element. Therefore, even if the frame frequency is lowered, the brightness of the liquid crystal display device can be maintained. .

[0518] That is, as shown in FIG. 58(B), for example, it is possible to rewrite an image once every five seconds. This allows users to see the same image as much as possible, and reduces the flickering of the screen that is visible to the user. This reduces stimulation to the retina, nerves, and brain of the user, and reduces nervous system fatigue. is reduced.

[0519] According to one embodiment of the present invention, a liquid crystal display device that is gentle on the eyes can be provided.

[0520] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

[0521] (Embodiment 12) In this embodiment, structural examples of electronic devices to which the display device of one embodiment of the present invention is applied will be described. In addition, in this embodiment, a display module to which the display device of one embodiment of the present invention is applied will be described. The rule will be explained using FIG. 59.

[0522] The display module 8000 shown in FIG. 59 includes an upper cover 8001 and a lower cover 8002. Between them, touch panel 8004 connected to FPC8003 and A display panel 8006, a backlight unit 8007, a frame 8009, a printed circuit board The backlight unit 8007, the battery 8011, and the The telly 8011, the touch panel 8004, etc. may not be provided.

[0523] The display device of one embodiment of the present invention can be used for the display panel 8006, for example.

[0524] The upper cover 8001 and the lower cover 8002 are connected to the touch panel 8004 and the display panel The shape and dimensions can be changed as needed to fit the size of the 8006.

[0525] The touch panel 8004 is a resistive or capacitive touch panel. The display panel 8006 can be used by overlapping it with the opposing substrate (sealing substrate). It is also possible to provide a touch panel function to the display panel. It is also possible to provide an optical sensor in each pixel of the 8006 to create an optical touch panel. Alternatively, a touch sensor electrode may be provided in each pixel of the display panel 8006, and a capacitive touch sensor may be used. It is also possible to use it as a touch panel.

[0526] The backlight unit 8007 includes a light source 8008. It may be provided at the end of the light source unit 8007 and may be configured to use a light diffusion plate.

[0527] The frame 8009 has a function of protecting the display panel 8006 and also a function of preventing the movement of the printed circuit board 8010. It also functions as an electromagnetic shield to block electromagnetic waves generated by the operation of the The frame 8009 may also function as a heat sink.

[0528] The printed circuit board 8010 includes a power supply circuit, a signal circuit for outputting a video signal and a clock signal. The power supply circuit is provided with a signal processing circuit. Alternatively, the power source may be a battery 8011 provided separately. 1 can be omitted if commercial power is used.

[0529] The display module 8000 also includes components such as a polarizing plate, a retardation plate, and a prism sheet. Additional ones may be provided.

[0530] FIG. 60 is an external view of an electronic device including a display device of one embodiment of the present invention.

[0531] Examples of electronic devices include television sets (televisions or television receivers) (also called "computer monitors"), cameras such as digital cameras and digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), Examples include large game machines such as small game machines, mobile information terminals, sound reproduction devices, and pachinko machines. can be.

[0532] FIG. 60(A) shows a portable information terminal, which includes a main body 1001, a housing 1002, a display unit 1003, and a display unit 1004. The display unit 1003a, 1003b, etc. The display unit 1003b is a touch panel. By touching the keyboard button 1004 displayed on the display unit 1003b, Of course, the display unit 1003a can be configured as a touch panel. The transistor described in the above embodiment may be used as a switching element in a liquid crystal panel. By fabricating a display panel or an organic light-emitting panel and applying it to the display parts 1003a and 1003b, This makes it possible to provide a highly reliable portable information terminal.

[0533] The portable information terminal shown in FIG. 60(A) displays various information (still images, videos, text images, etc.) Functions that display calendars, dates, or times on the display, functions that display Functions for manipulating or editing displayed information, processing by various software (programs) In addition, external connection terminals can be provided on the back and sides of the housing. It may also be configured to include a connector (such as an earphone jack or USB terminal), a recording medium insertion section, etc.

[0534] The portable information terminal shown in FIG. 60(A) is configured to be capable of transmitting and receiving information wirelessly. You can also purchase and download desired book data from an electronic book server wirelessly. It is also possible to configure it so that it is downloaded.

[0535] FIG. 60(B) shows a portable music player, and the main body 1021 has a display unit 1023 and earphones. a fixing part 1022 for attaching to a speaker, an operation button 1024, an external memory slot, The transistor shown in the above embodiment is a switching transistor. By manufacturing a liquid crystal panel or an organic light-emitting panel as an element and applying it to the display unit 1023, This makes it a more reliable portable music player.

[0536] Furthermore, the portable music player shown in Figure 60(B) is equipped with an antenna, microphone function, and wireless function. If you carry it and connect it to your mobile phone, you can enjoy wireless hands-free driving while driving a car. Conversations in Lee are also possible.

[0537] FIG. 60(C) shows a mobile phone, which is composed of two housings, housing 1030 and housing 1031. The housing 1031 is provided with a display panel 1032, a speaker 1033, a microphone, and the like. Phone 1034, pointing device 1036, camera 1037, external connection terminal 103 The housing 1030 also includes a solar cell 1040 for charging the mobile phone. , an external memory slot 1041, etc. The antenna is located inside the housing 1031. The transistor described in the above embodiment is applied to the display panel 1032. This makes it possible to make the mobile phone highly reliable.

[0538] The display panel 1032 is also equipped with a touch panel, and the image displayed on the display panel 1032 is shown in FIG. The multiple operation keys 1035 are indicated by dotted lines. A boost circuit is also implemented to boost the voltage received to the voltage required for each circuit.

[0539] The display direction of the display panel 1032 changes appropriately depending on the mode of use. The camera 1037 is located on the same surface as the screen 1032, making it possible to make video calls. The speaker 1033 and microphone 1034 are not limited to voice calls, but also for video calls, recording, Furthermore, the housing 1030 and the housing 1031 can be slid to separate the two. C) It can be folded from the unfolded state to the folded state, making it small and easy to carry. It can be categorized.

[0540] The external connection terminal 1038 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. By inserting a recording medium into the external memory slot 1041, it is possible to store and transfer a larger amount of data. Cut.

[0541] In addition to the above functions, it also has infrared communication functions, TV reception functions, etc. Good too.

[0542] FIG. 60(D) shows an example of a television device. The television device 1050 is A display unit 1053 is built into the housing 1051. The display unit 1053 displays an image. In addition, the CPU is built into the stand 1055 that supports the housing 1051. The transistor described in the above embodiment is applied to the display portion 1053 and the CPU. By using this, television device 1050 can be made highly reliable.

[0543] The television device 1050 can be operated using an operation switch provided on the housing 1051 or a separate remote control. This can be done by a remote controller. A display unit for displaying information output from the machine may be provided.

[0544] The television device 1050 is configured to include a receiver, a modem, and the like. It is possible to receive general television broadcasts, and also to receive wired or wireless signals via a modem. By connecting to a communication network, it can be one-way (sender to receiver) or two-way It is also possible to communicate information in both directions (between a sender and a receiver, or between receivers). .

[0545] The television device 1050 also includes an external connection terminal 1054 and a storage medium playback / recording unit 1055. 052, and an external memory slot. The external connection terminal 1054 is for connecting a USB cable or the like. It can be connected to any type of cable, enabling data communication with a personal computer, etc. In the storage medium playback / recording unit 1052, a disk-shaped recording medium is inserted and It is possible to read the stored data and write it to the recording medium. Images and videos stored in the external memory 1056 inserted in the reslot It is also possible to display it on the display unit 1053.

[0546] In addition, when the off-leak current of the transistor described in the above embodiment is extremely small, By applying this transistor to the external memory 1056 or the CPU, power consumption can be reduced sufficiently. This can result in a highly reliable television device 1050 with reduced power consumption.

[0547] Note that the structures and methods described in this embodiment may be different from the structures and methods described in other embodiments. They can be used in appropriate combination.

Claims

1. A display device including a plurality of pixels each including a transistor and a capacitor electrically connected to the transistor, a first conductive film that functions as a first gate electrode of the transistor; a first insulating film having a region located above the first conductive film and including silicon nitride; a second insulating film having a region located above the first insulating film and including silicon oxide; an oxide semiconductor film having a region in contact with a top surface of the second insulating film and including a channel formation region of the transistor; a second conductive film having a region in contact with an upper surface of the second insulating film and functioning as one electrode of the capacitor element; a third insulating film having a region in contact with a top surface of the oxide semiconductor film and a region in contact with a top surface of the second conductive film, the third insulating film including silicon oxide; a fourth insulating film having a region located above the third insulating film and including silicon nitride; a third conductive film having a region in contact with a top surface of the fourth insulating film, overlapping with the oxide semiconductor film with the third insulating film and the fourth insulating film interposed therebetween, and functioning as a second gate electrode of the transistor; a fourth conductive film having a region in contact with an upper surface of the fourth insulating film, overlapping with the second conductive film, and functioning as a second electrode of the capacitor; a fifth insulating film having a region located above the third conductive film and a region located above the fourth conductive film, and having an organic substance; a fifth conductive film having a region located above the fifth insulating film and functioning as a pixel electrode; the third insulating film has a thickness greater than the thickness of the fourth insulating film; the third insulating film has a first opening in a region overlapping with the second conductive film and does not have an opening in a region overlapping with the oxide semiconductor film; In the first opening, the fourth insulating film has a region in contact with an upper surface of the second conductive film, the fifth insulating film has a second opening in a region overlapping with the fourth conductive film; In the second opening, the fifth conductive film has a region in contact with an upper surface of the fourth conductive film, In a plan view, an area of ​​the first opening is larger than an area of ​​the second opening, the fifth conductive film does not overlap with the oxide semiconductor film.

2. A display device including a plurality of pixels each including a transistor and a capacitor electrically connected to the transistor, a first conductive film that functions as a first gate electrode of the transistor; a first insulating film having a region located above the first conductive film and including silicon nitride; a second insulating film having a region located above the first insulating film and including silicon oxide; an oxide semiconductor film having a region in contact with a top surface of the second insulating film and including a channel formation region of the transistor; a second conductive film having a region in contact with an upper surface of the second insulating film and functioning as one electrode of the capacitor element; a third insulating film having a region in contact with a top surface of the oxide semiconductor film and a region in contact with a top surface of the second conductive film, the third insulating film including silicon oxide; a fourth insulating film having a region located above the third insulating film and including silicon nitride; a third conductive film having a region in contact with a top surface of the fourth insulating film, overlapping with the oxide semiconductor film with the third insulating film and the fourth insulating film interposed therebetween, and functioning as a second gate electrode of the transistor; a fourth conductive film having a region in contact with an upper surface of the fourth insulating film, overlapping with the second conductive film, and functioning as a second electrode of the capacitor; a fifth insulating film having a region located above the third conductive film and a region located above the fourth conductive film, and having an organic substance; a fifth conductive film having a region located above the fifth insulating film and functioning as a pixel electrode; the third insulating film has a thickness greater than the thickness of the fourth insulating film; the third insulating film has a first opening in a region overlapping with the second conductive film and does not have an opening in a region overlapping with the oxide semiconductor film; In the first opening, the fourth insulating film has a region in contact with an upper surface of the second conductive film, the fifth insulating film has a second opening in a region overlapping with the fourth conductive film; In the second opening, the fifth conductive film has a region in contact with an upper surface of the fourth conductive film, In a plan view, an area of ​​the first opening is larger than an area of ​​the second opening, the first insulating film has a thickness greater than the thickness of the second insulating film; the fifth conductive film does not overlap with the oxide semiconductor film.

3. A display device including a plurality of pixels each including a transistor and a capacitor electrically connected to the transistor, a first conductive film that functions as a first gate electrode of the transistor; a first insulating film having a region located above the first conductive film and including silicon nitride; a second insulating film having a region located above the first insulating film and including silicon oxide; an oxide semiconductor film having a region in contact with a top surface of the second insulating film and including a channel formation region of the transistor; a second conductive film having a region in contact with an upper surface of the second insulating film and functioning as one electrode of the capacitor element; a third insulating film having a region in contact with a top surface of the oxide semiconductor film and a region in contact with a top surface of the second conductive film, the third insulating film including silicon oxide; a fourth insulating film having a region located above the third insulating film and including silicon nitride; a third conductive film having a region in contact with a top surface of the fourth insulating film, overlapping with the oxide semiconductor film with the third insulating film and the fourth insulating film interposed therebetween, and functioning as a second gate electrode of the transistor; a fourth conductive film having a region in contact with an upper surface of the fourth insulating film, overlapping with the second conductive film, and functioning as a second electrode of the capacitor; a fifth insulating film having a region located above the third conductive film and a region located above the fourth conductive film, and having an organic substance; a fifth conductive film having a region located above the fifth insulating film and functioning as a pixel electrode; the third insulating film has a thickness greater than the thickness of the fourth insulating film; the third insulating film has a first opening in a region overlapping with the second conductive film and does not have an opening in a region overlapping with the oxide semiconductor film; In the first opening, the fourth insulating film has a region in contact with an upper surface of the second conductive film, the fifth insulating film has a second opening in a region overlapping with the fourth conductive film; In the second opening, the fifth conductive film has a region in contact with an upper surface of the fourth conductive film, In a plan view, an area of ​​the first opening is larger than an area of ​​the second opening, the fifth conductive film does not overlap with the oxide semiconductor film, a first conductive film overlapping the oxide semiconductor film along an entire periphery thereof in a plan view;

4. A display device including a plurality of pixels each including a transistor and a capacitor electrically connected to the transistor, a first conductive film that functions as a first gate electrode of the transistor; a first insulating film having a region located above the first conductive film and including silicon nitride; a second insulating film having a region located above the first insulating film and including silicon oxide; an oxide semiconductor film having a region in contact with a top surface of the second insulating film and including a channel formation region of the transistor; a second conductive film having a region in contact with an upper surface of the second insulating film and functioning as one electrode of the capacitor element; a third insulating film having a region in contact with a top surface of the oxide semiconductor film and a region in contact with a top surface of the second conductive film, the third insulating film including silicon oxide; a fourth insulating film having a region located above the third insulating film and including silicon nitride; a third conductive film having a region in contact with a top surface of the fourth insulating film, overlapping with the oxide semiconductor film with the third insulating film and the fourth insulating film interposed therebetween, and functioning as a second gate electrode of the transistor; a fourth conductive film having a region in contact with an upper surface of the fourth insulating film, overlapping with the second conductive film, and functioning as a second electrode of the capacitor; a fifth insulating film having a region located above the third conductive film and a region located above the fourth conductive film, and having an organic substance; a fifth conductive film having a region located above the fifth insulating film and functioning as a pixel electrode; the third insulating film has a thickness greater than the thickness of the fourth insulating film; the third insulating film has a first opening in a region overlapping with the second conductive film and does not have an opening in a region overlapping with the oxide semiconductor film; In the first opening, the fourth insulating film has a region in contact with an upper surface of the second conductive film, the fifth insulating film has a second opening in a region overlapping with the fourth conductive film; In the second opening, the fifth conductive film has a region in contact with an upper surface of the fourth conductive film, In a plan view, an area of ​​the first opening is larger than an area of ​​the second opening, the first insulating film has a thickness greater than the thickness of the second insulating film; the fifth conductive film does not overlap with the oxide semiconductor film, a first conductive film overlapping the oxide semiconductor film along an entire periphery thereof in a plan view;

Images