Display 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 present invention relates to a method, 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. The silicon semiconductor is made of silicon semiconductor such as polycrystalline silicon or polysilicon. Transistors using semiconductors are also used in integrated circuits (ICs).

[0003] In recent years, metal oxides that exhibit semiconducting properties have been used in transistors instead of silicon semiconductors. In this specification, the term "oxide" refers to a metal oxide that exhibits semiconductor properties. Let us call them semiconductors.

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

[0005] [Patent Document 1] JP 2007-123861 A [Patent Document 2] JP 2007-96055 A Summary of the Invention [Problem to be solved by the invention]

[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 conductive film is used.

[0007] In addition, in a liquid crystal display device, the larger the capacitance value of the capacitance element, the more In the liquid crystal display device, 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 is 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 provided to increase the area where a pair of electrodes overlap. If the area of ​​the film is increased, the aperture ratio of the pixel is reduced, and the display quality of the image is degraded. 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, This leads to a problem that the amount of variation 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 becomes easier to operate, or power consumption during non-operation increases, or in the case of display devices, This causes various problems, such as a decrease in cost, which in turn causes a decrease in display quality.

[0010] In view of the above, 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 provides a novel display device. To provide a method for manufacturing a display device having 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. Other issues can be extracted 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 capacitance 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 capacitance 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 overlapping 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 insulating film; an inorganic insulating film; and a first light-transmitting conductive film on the inorganic insulating film. The pixel electrode is formed of a second conductive film having a light-transmitting property and has a pair of conductive films. Contact with one side.

[0014] The above transistor has a gate electrode overlapping 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 on 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 an oxide insulating film in contact with the other surface of the oxide semiconductor film and an oxide insulating film in contact with the other surface of the oxide semiconductor 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 has the same metal as the oxide semiconductor film. The element may include elements of the group.

[0017] The oxide semiconductor film is an In-Ga oxide, an In-Zn oxide, or an In-Mn oxide. n oxide (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. The first film is The atomic ratio of the metal elements in the second film may be different from that in the first film. Effect 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 having a transistor can be provided. It is possible to manufacture a display device with a high aperture ratio and a wide viewing angle 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 are described in the specification. The above will become apparent from the description, drawings, claims, etc. From the above description, it is possible to extract other effects. [Brief description of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 2] 1A and 1B are a block diagram and a circuit diagram illustrating one embodiment of a semiconductor device. [Diagram 3] FIG. 1 is a top view illustrating one embodiment of a semiconductor device. [Figure 4] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 5] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Figure 6] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Figure 7] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Figure 8] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Figure 9] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Figure 10] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Figure 11] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 12] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 13] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 14] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 15] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 16] 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] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 19]1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Figure 20] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Figure 21] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Figure 22] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Figure 23] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 24] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 25] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 26] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 27] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 28] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 29] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 30] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 31] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 32] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 33] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 34] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Diagram 35] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Diagram 36] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Figure 37] 1A to 1C are cross-sectional views illustrating one mode of a method for manufacturing a semiconductor device. [Figure 38] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 39] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 40] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 41] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 42] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 43] 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 44] Cs-corrected high-resolution TEM image of a cross section of CAAC-OS, and a schematic cross-sectional diagram of CAAC-OS. [Diagram 45] Cs-corrected high-resolution TEM image of the CAAC-OS in the plane. [Figure 46] 13A to 13C show 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 crystal part of an In-Ga-Zn oxide due to electron irradiation. [Figure 49] Schematic diagram explaining the film formation model of CAAC-OS and nc-OS. [Figure 50] A diagram explaining InGaZnO4 crystals and pellets. [Figure 51] Schematic diagram explaining 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 atoms collide. [Figure 54] A diagram explaining the structure of InGaZnO4 after atomic collisions. [Figure 55] A diagram explaining the trajectory of atoms after they collide. [Figure 56] Cross-sectional HAADF-STEM images of CAAC-OS and the target. [Figure 57] FIG. 4 is a diagram illustrating the temperature dependence of resistivity. [Figure 58] FIG. 1 is a conceptual diagram showing 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 PREFERRED EMBODIMENTS

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

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

[0023] In addition, the terms "first," "second," "third," etc., used in this specification are used interchangeably to avoid confusion of components. The number is added for convenience and is not intended to be a numerical limit. The terms can be replaced with "second" or "third" as appropriate for explanation.

[0024] The function of the "source" and "drain" is to change the direction of the current 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 is the potential difference between two points, and potential is the electrostatic field at a certain point. This refers to the electrostatic energy (electrical potential energy) possessed by a unit charge in a particle. Generally, the potential difference between a 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, potential may be read as voltage. In this specification, voltage may be read as potential.

[0026] In this specification, when an etching process is performed after a photolithography process, 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 where the angle is between -5° and 5°. 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 which is one embodiment of the present invention will be described with reference to drawings. .

[0030] FIG. 1 shows 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, and 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 and the conductive film 310e are provided.

[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 302 and the metal oxide film 308c. 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, alkali By introducing impurities such as lithium-earth metals or oxygen deficiencies, the electrical conductivity is improved, and the electrical conductivity is improved. Since the oxide semiconductor film has a light-transmitting property, the metal oxide film 3 08c also has translucency.

[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 capacitance 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 a 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 insulating 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 causes 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 are prevented from entering the oxide semiconductor film 308b. The amount of diffusion of elements such as silicon can be reduced, and the amount of defects in the oxide semiconductor film 308b can be reduced. For this reason, in the inorganic insulating film 53, 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 semiconductor material used 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 organic insulating film 317 has a thickness of 500 nm or more and a thickness of 500 nm or less. 0 nm or less, preferably 1000 nm or more and 3000 nm or less.

[0039] In addition, the conductive film 319 formed on the organic insulating film 317 is a transistor 103 and a capacitor The conductive film 319 functions as a pixel electrode and is connected to the inorganic insulating film 53 and the organic insulating film 54. The conductive layer 317 is connected to the transistor 103 through an opening formed in the conductive insulating layer 317. Since the film 319 is spaced apart from the transistor 103, the conductive property of the transistor 103 is not affected. As a result, the conductive film 319 is not easily affected by the potential of the film 310d. They can be overlapped, and the aperture ratio of the pixel can be increased.

[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 charged to the inorganic insulating film 5. 3, and the surface of the inorganic insulating film 53 is weakly positively charged.

[0042] Positive charges are applied to the surface of the inorganic insulating film 53, generating an electric field, which then causes the oxide 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 substantially applied to the interface between the insulating film 53 and the insulating film 54. This causes the threshold voltage of the transistor to shift negatively.

[0043] On the other hand, the transistor 103 according to this embodiment shown in FIG. The insulating film 317 is thick, having 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 effect 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 is thick, having 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 interface between the oxide semiconductor film 308b and the inorganic insulating film 53 is not easily affected. At the interface of the transistor 3, a positive bias is not substantially applied, 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, which diffuses 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 the variation in electrical characteristics. In addition, it has normally-off characteristics and is highly reliable. In addition, the organic insulating film can be formed by a printing method or a coating method. Since the film can be formed using a metal such as fluorine, the manufacturing time can be shortened. 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 is 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 is formed. Therefore, the oxide semiconductor film 308e and the pair of conductors 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 conductors. The conductive films 310f and 310g are partially protruding from the outside.

[0049] <Variation 2> In the display device shown in the first embodiment, depending on circumstances or situations, for example, For example, the conductive film 319 may be formed using a conductive film having a function of reflecting light. Alternatively, the conductive film 319 is formed using a laminated film, and at least one of the laminated films is 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 (ITO) films. In such a case, a reflective display device, a semi-transmissive display device, a transflective display device, a This embodiment can be applied to a light emitting device having 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 parallel or substantially parallel to each other. m scanning lines 17 arranged in rows and whose potentials are controlled by a scanning line driving circuit 14; The respective electrodes are arranged in parallel or approximately in parallel, and the potentials of the electrodes are controlled by a signal line driving circuit 16. The pixel section 11 has a number of signal lines 19. 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 each other along the scanning lines 17. The scanning line driving circuit 14 and the signal line driving circuit 16 may be arranged in a row. This may be referred to as the drive circuit section.

[0053] The display 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 on the substrate It is sometimes called a liquid crystal module.

[0054] Each scanning line 17 corresponds 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 each row. Among the pixels 301 arranged in n rows and n columns, m pixels 301 arranged in any one of the columns are electrified. m and n are integers of 1 or more. Each of the capacitance lines 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 connected parallel or substantially parallel to the signal lines 19. If the pixel is arranged in m rows and n columns, the pixel is arranged in any one of the columns. The pixel 301 is electrically connected to the m pixels 301 arranged in the pixel area.

[0055] In this case, one pixel is defined as an area surrounded by scanning lines and signal lines and exhibiting one color. For this reason, 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 composed of three pixels: an R pixel, a G pixel, and a B pixel. In addition, you can add pixels of yellow, cyan, magenta, etc. to R (red), G (green), and B (blue). This allows for improved color reproducibility. In addition, R (red), G (green), B (blue), and W (white) By adding the pixel, the power consumption of the display device can be reduced. In the case of , adding a W (white) pixel to each of R (red), G (green), and B (blue) Since it is possible to increase the brightness of the backlight, the brightness of the backlight can 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 appropriately set according to the specifications of the pixel 301. The alignment state of the liquid crystal element 31 is set by the written data. A common potential (common potential) is applied to one of a 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 row of pixels 301. 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 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 vertical electric field or an oblique electric field). , nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, thermotropic liquid crystal, Examples of the liquid crystal 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, a TN mode or a VA mode. , ASM(Axially Symmetric Aligned Micro-cel l) mode, OCB (Optically Compensated Birefring ingression mode, MVA mode, PVA (Patterned Vertical Alignment) mode, IPS mode, FFS mode, or TBA (Trans You can also use the (Verse Bend Alignment) mode. However, 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 liquid crystal that exhibits the blue phase. 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. 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 line 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 capacitance line 25 to which a potential is supplied, and the other end is connected to one of a pair of electrodes of the liquid crystal element 31. The potential value of the capacitance line 25 is set according to the specifications of the pixel 301. The capacitance element 105 functions as a storage capacitor for storing written data. Possesses the ability.

[0064] For example, in a display device having the pixel 301 shown in FIG. 2B, each pixel is driven by 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 of the data signal. Write.

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

[0066] In addition, the pixel 301 shown in FIG. 2C includes a transistor 4 for switching the display element. 3, a transistor 103 for controlling the driving of the pixel, a transistor 45, and a capacitance element 10 5 and a light-emitting element 41.

[0067] One of the source and drain electrodes 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 gate signal line 19. is electrically connected to a scan line 17 to which

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

[0069] One of the source electrode and the drain electrode of the transistor 103 functions as an anode line. The source electrode and the drain electrode of the transistor 103 are electrically connected to the wiring 47. 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 capacitance 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 the

[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 a light-emitting 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 a 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, for example, 0V.

[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 transistor 43 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 element 105 It has a function as a storage capacitor for storing 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 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 electrode 52 is electrically connected to a wiring 50 which functions as a

[0076] The light-emitting element 41 is, for example, an organic electroluminescence element (also called an organic EL element). However, the light emitting element 41 is not limited to this, and any other suitable element may be used. 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. The power supply potential VSS is applied to the wiring 50 and the low power supply potential VSS is applied to the wiring 50.

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

[0079] The pixel 301 to which the data has been written is in a holding state by turning off the transistor 43. 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 with a brightness that corresponds to the amount of current flowing through them. By performing this process row by row, 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, organic EL elements, inorganic EL elements), LEDs (white LEDs, red LEDs (color LEDs, green LEDs, blue LEDs, etc.), transistors (transistors that emit light according to the current , electron emission element, liquid crystal element, electronic ink, electrophoretic element, grating light Valve (GLV), Plasma Display (PDP), MEMS (Micro Electro 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. An example of a display device using an EL element is an EL display. An example of a display device using electron emission elements is the field emission type. Flat-panel display (FED) or SED type flat panel display (SED: Surface 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, semi-transmissive LCD, reflective LCD, direct-view LCD Display devices using electronic ink or electrophoretic elements. 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 conductors (the left-right direction in the drawing). 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 2. The scanning line driver circuit 14 is electrically connected to the scanning line driver circuit 14 (see FIG. 2) and functions as a signal line. 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 functioning as a scan line and a conductive film functioning as a signal line. The transistor 103 is provided in a region where the two intersect. A conductive film 304c, 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 a pair of conductive films 310d and 310e. The region overlapping with the oxide semiconductor film 308b also functions as a conductive film. It also functions as a gate electrode of the transistor 103. In FIG. An end portion of the conductive film is located outside an end 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 shown by a dashed line in the insulating film provided on the metal oxide film 308c is 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. 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 a light-transmitting property. has light-transmitting properties.

[0086] The conductive film 319 that functions as a pixel electrode is connected via an organic insulating film (not shown in FIG. 3). 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 is 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 having an increased capacitance value, while increasing the capacitance to 60% or more. For example, in a high-resolution display device, such as a liquid crystal display device, the pixel surface Therefore, the capacitance element area is small. Therefore, the capacitance value stored in the capacitive element becomes smaller. 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 pi or higher, even 300ppi or higher, or even 500ppi or higher. The present invention can be suitably used in such a case.

[0088] In addition, in a liquid crystal display device, the larger the capacitance value of the capacitance element, the more In the liquid crystal display device, 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 frequency with which image data is rewritten. It is possible to reduce the number of circuits, and therefore the power consumption. The structure shown in FIG. 1 can increase the aperture ratio even in a high-resolution display device. It is possible to efficiently use light from light sources such as backlights, thereby reducing the power consumption of display devices. It is possible.

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

[0090] The liquid crystal display device shown 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 , 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 element 322 .

[0092] Thus, a liquid crystal display device is a device that has liquid crystal elements. The liquid crystal display 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., are arranged in It is also called a liquid crystal module.

[0093] In the driving circuit section, a conductive film 304a functioning as a gate electrode, a gate insulating film 51, the insulating film 305 and the insulating film 306 which 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 constitutes 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 A channel region formed on the insulating film 305 and insulating film 306 that function and the gate insulating film 51 The oxide semiconductor film 308b on which the conductive layer is formed functions as a source electrode and a drain electrode. The films 310d and 310e constitute the transistor 103. The oxide semiconductor film 308b , and are provided on the gate insulating film 51. In addition, inorganic insulating The insulating films 312 and 314, which are the film 53, are provided as protective films.

[0095] In addition, a metal oxide film 308c functions as one electrode, and an insulating film functions as a dielectric film. The capacitor 105 is formed by the film 314 and the conductive film 316b functioning as the other electrode. 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 functioning 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 0c is connected 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] Here, the components of the display device shown in FIG. 4 will be described below.

[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 a 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 sa A fire substrate or the like may be used as the substrate 302. Also, a substrate made of silicon or silicon carbide may be used. A single crystal semiconductor substrate, a polycrystalline semiconductor substrate, a silicon germanium substrate, etc. 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 having a gate electrode 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 Using large area substrates such as 10th generation (2950mm x 3400mm) By this, a large liquid crystal display device can be manufactured.

[0102] In addition, a flexible substrate is used as the substrate 302, and a transistor is formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate 302 and the transistor. After completing a part or the whole of the element part on it, it is separated from the substrate 302 and attached to another substrate. In this case, the transistors can be mounted on substrates with poor heat resistance or flexible substrates. It can also be printed on other circuit boards.

[0103] The conductive films 304a, 304b, and 304c may be made of aluminum, chromium, copper, or tantalum. , titanium, molybdenum, tungsten, or the above-mentioned metal elements The alloy may be formed using an alloy containing the above-mentioned metal elements or a combination of 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 layer structure. For example, a single layer structure of an aluminum film containing silicon, A two-layer structure in which a titanium film is laminated on a titanium nitride film, a two-layer structure in which a titanium film is laminated on a titanium nitride film, A two-layer structure in which a tungsten film is laminated on a titanium nitride film, a tantalum nitride film or a tungsten nitride film A two-layer structure in which a tungsten film is laminated on a stainless film, a titanium film, and an aluminum film on the titanium film. There are three-layer structures, such as a laminate of an aluminum film and a titanium film on top of that. Titanium, tantalum, tungsten, molybdenum, chromium, neodymium, scandium Alternatively, an alloy film made by combining one or more of the above metals or a nitride film 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, the conductive material having light transmitting properties and the metal element may be laminated. It is also possible.

[0105] An insulating film 305, an insulating film 306, and an insulating film 307 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 transistor of the driving circuit section. The gate insulating film 51 functions as the gate insulating film 51 of the transistor of the pixel section 11. do.

[0106] The insulating film 305 may be, for example, a silicon nitride film, a silicon oxynitride 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 of a metal oxide or the like, and may be formed as a stacked layer or a single layer. As an example, 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 can reduce 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] On the insulating film 306, oxide semiconductor films 308a and 308b and a metal oxide film 308c are formed. 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. The conductive film 304b is formed in a position overlapping 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: a, Y, Zr, La, Ce, Nd, Sn, or Hf. 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 n-oxide, 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 peak 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 of 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 are each the above atomic ratios plus the error. Includes a minus 20% fluctuation.

[0115] The oxide semiconductor films 308a and 308b and the metal oxide film 308c are, for example, The non-single crystal structure may be, for example, a CAAC-OS (C Axis Aligned Crystalline Oxide Semiconductor) , polycrystalline structure, microcrystalline structure described later, or amorphous structure. The amorphous structure has the highest density of defect states, and 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. Crystal structure region, polycrystalline structure region, CAAC-OS region, or single crystal structure region In some cases, the mixed film has a single layer structure or a single layer structure having two or more regions. 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. As a result, 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 metal or alkaline earth metal in the solution is 1×10 18 atoms / cm 3 Below Lower, preferably 2 x 10 16 atoms / cm 3 The following are alkali metals and alkalis: When an earth metal combines with an oxide semiconductor, it can generate carriers, which can be used to As a result, the off-state current of the oxide semiconductor films 308a and 308b may increase. It is preferred to reduce the concentration of alkali or alkaline earth metals.

[0119] In addition, when the oxide semiconductor films 308a and 308b contain nitrogen, the charge carrier This causes the electrons to be generated, increasing the carrier density and making 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 To be more specific: is preferred.

[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 or equal to 1×10 15 pieces / cm 3 Less than 1×10, more preferably 13 pieces / cm 3 Less than or equal to 1×10 11 pieces / cm 3 The following oxide semiconductor film is used.

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

[0122] The oxide semiconductor films 308a and 308b are formed by forming the oxide semiconductor film 308a and the oxide semiconductor film 308b on 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 acid-resistant. 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. In this embodiment, 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 means that the 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, the 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 intrinsic or substantially highly purified intrinsic has an extremely small off-state current. Channel width is 1×10 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 Characteristics below A Therefore, a transistor having a channel region in the oxide semiconductor film can be obtained. In some cases, the variation in electrical characteristics of the transistor is small, resulting in a highly reliable transistor. Charges trapped in the trap states of the oxide semiconductor film take a long time to disappear. Therefore, oxides with high trap state density can be used. Transistors in which the channel region is formed in a semiconductor film may have unstable electrical characteristics. The impurities include hydrogen, nitrogen, alkali metals, and alkaline earth metals.

[0124] The metal oxide film 308c is an oxide semiconductor 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 and the oxide semiconductor film 308b each contain the same metal element. , 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 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. This film was formed at the same time as 308b, and oxygen vacancies were formed due to plasma damage, etc. Alternatively, the metal oxide film 308c is a film having enhanced electrical conductivity. It is a film formed at the same time as 8a and 308b, contains impurities, and has plasma damage. The film has oxygen vacancies due to oxidation, etc., and has high electrical conductivity.

[0125] Therefore, the oxide semiconductor films 308a and 308b and the metal oxide film 308c are both 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 5×10 18 atoms / cm 3 Less than or equal to 1×10 18 atoms / cm 3 Less than or equal to 5×10 17 atoms / cm 3 Less than or equal to 1×10 16 atoms / cm 3 Metal The hydrogen concentration in the oxide film 308c is 8×10 19 atoms / cm 3 The above is preferable. is 1×10 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 plasma-treated. 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 the oxide semiconductor film by plasma CVD or sputtering. Then, the oxide semiconductor film is exposed to the plasma, and oxygen vacancies are generated. In the etching treatment for forming the oxide semiconductor film 12, the oxide semiconductor film is exposed to plasma. Alternatively, the oxide semiconductor film is exposed to hydrogen, a rare gas, ammonia, or an acid. When the silicon substrate is exposed to a plasma of a mixture of nitrogen and hydrogen gas, 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 having high conductivity. It can also be said that the metal oxide film 308c is formed of a metal oxide film having high conductivity.

[0128] In addition, when a silicon nitride film is used as the insulating film 314, the silicon nitride film contains hydrogen. For this reason, hydrogen is formed in the insulating film 314 at the same time as the oxide semiconductor films 308a and 308b. When hydrogen diffuses into the oxide semiconductor film, the hydrogen bonds with oxygen in the oxide semiconductor film and becomes a carrier. In addition, the silicon nitride film is 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 act as carriers, are generated. As a result, the conductivity of the oxide semiconductor film becomes high and the oxide semiconductor film becomes the 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 electrical conductivity. The oxide semiconductor that has been made a conductor 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 in the vicinity of the conduction band. The effect of absorption due to the core level is small, and the transparent property 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 preferable that the ratio is 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. 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] In addition, 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 may be formed by mixing the oxide semiconductor films 308a and 308b with For example, the metal oxide film 308c may be made of ITO or ITO. The insulating layer 11 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. This makes it possible to increase the aperture ratio of the pixel while increasing the area occupied by the pixel.

[0134] The conductive films 310a, 310b, 310c, 310d, and 310e are made of aluminum. Minium, 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 multilayer structure. For example, a single layer structure of an aluminum film containing silicon is used. A two-layer structure in which a titanium film is laminated on an aluminum film, and a titanium film is laminated on a tungsten film a two-layer structure in which a copper film is laminated on a copper-magnesium-aluminum alloy film; A titanium film or titanium nitride film and an aluminum film overlaid on the titanium film or titanium nitride film. A three-layer structure is formed by laminating a titanium film or a copper film on top of the titanium film or a titanium nitride film. A molybdenum film or a molybdenum nitride film and the molybdenum film or the 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 On the films 310a, 310b, 310c, 310d, and 310e, the following inorganic insulating film 53 is formed: An insulating film 312 and an insulating film 314 are formed. The insulating film 312 is similar to the insulating film 306. In addition, it is preferable to use a material capable of improving 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, 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 composition in which the oxygen content is higher than that of nitrogen. A silicon nitride oxide film is a film that contains more nitrogen than oxygen. This refers to a thin membrane.

[0138] The insulating film 312a is an oxide insulating film that contains 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 oxynitride film, etc.

[0140] The oxide insulating film containing nitrogen and having few defects was measured at ESR of 100K or less. The first signal in the spectrum with a g-value between 2.037 and 2.039, The second signal has a g value between 2.001 and 2.003, and the 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 about 5m in X-band measurement. T. The first signal has a g value of 2.037 to 2.039, and the second signal has a g value of 2.0 A second signal with a g value between 1.01 and 2.003, and a second signal with 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 in the ESR spectrum below 100K is 2.037 to 2.039. The first signal has a g value of 2.001 to 2.003, and the second signal has a g value of 1 The third signal, between .964 and 1.966, is nitrogen oxide (NO x , x is 0 to 2 Representative examples of nitrogen oxides include: , nitrogen monoxide, nitrogen dioxide, etc. That is, the first group with a g value of 2.037 to 2.039. a signal with a g value between 2.001 and 2.003, and a second signal with a g value between 1.9 The lower the sum of the spin densities of the third signals, which are greater than or equal to 64 and less than or equal to 1.966, the higher the oxidation It can be said that the content of nitrogen oxides in the insulating film is small.

[0142] If the insulating film 312a contains a small amount of nitrogen oxide 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 variation in the threshold voltage of a transistor included in a semiconductor device. As a result, the fluctuation in the electrical characteristics of the transistor can be reduced.

[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 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 In addition, the threshold of the transistor included in the semiconductor device can be reduced. It is possible to reduce the shift in the low voltage and to reduce the variation in the electrical characteristics of the transistor. It is possible.

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

[0145] In the insulating film 312a, all of the oxygen that entered the insulating film 312a from the outside is Some oxygen does not move outside 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 transfer 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 in contact with the insulating film 312a. The oxide insulating film is formed using an oxide insulating film containing more oxygen than the oxygen that satisfies the stoichiometric composition. The oxide insulating film containing more oxygen than the stoichiometric composition loses part of the oxygen by heating. The oxide insulating film containing more oxygen than the stoichiometric composition has a T In the DS analysis, the amount of oxygen desorbed was 1.0 x 10 18 atoms / cm 3 More than 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 to 700°C. The range of 100° C. or higher and 500° C. or lower is preferable.

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

[0149] In addition, it is preferable that the insulating film 312b has a small amount of defects. Therefore, the spin density of the signal at g=2.001 originating from the silicon dangling bond is Degree is 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, an alkali metal, or an alkaline earth metal. By providing the nitride insulating film having a masking 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 of the films include silicon nitride film, silicon oxynitride film, aluminum nitride film, and aluminum oxynitride film. Examples include umbilical cord 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, yttrium nitride, hafnium oxide, and hafnium nitride. In order to control the capacitance 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 a light-transmitting property include indium oxide containing tungsten oxide, tungsten oxide, and the like. Indium zinc oxide containing ingested indium, indium oxide containing titanium oxide, titanium oxide Indium tin oxide containing silicon, ITO, indium zinc oxide, indium oxide 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 preferably 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, at least the film functions as a pixel electrode. The concave portion of the conductive film 316b can be filled with an organic insulating film 317. It is possible to reduce the alignment unevenness of the liquid crystal material constituting 1.

[0156] In addition, 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 through 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 connection 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 a 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 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 a single 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. An organic resin such as polyimide or epoxy resin can be used.

[0161] In addition, 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 and is adjacent to the light-shielding film 344. 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 any colored film that transmits light in a specific wavelength range. For example, A red (R) film transmits light in the red wavelength range, and a green (G) film transmits light in the green wavelength range. ) film, or a blue (B) film that transmits light in the blue wavelength range, etc. can be used.

[0163] The light-shielding film 344 may be made of a metal or other material as long as it has a function of blocking light in a specific wavelength range. Alternatively, 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 planarizing the The function of the colored film 346 is to prevent impurities contained therein from diffusing into 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 conductive film 350 and the pixel electrode 9 a.

[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 formed by sealing the substrate 302 and the substrate 342 with a sealing material (not shown). The seal is placed between the two to prevent moisture from entering from the outside. In particular, it is preferable that the inorganic material is in contact with the inorganic material.

[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 in the liquid crystal display device shown in FIG. 5 to 8. In this embodiment, 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.) are Sputtering method, Chemical Vapor Deposition (CVD) method, Vacuum evaporation method, Pulsed laser deposition (PL D) method. Alternatively, it can be formed by a coating method or a printing method. The film formation method is typically sputtering or plasma enhanced chemical vapor deposition (PECVD). Although it is typical, a thermal CVD method may also be used. An example of a thermal CVD method is MOCVD (metal organic chemical vapor deposition). A vapor phase deposition (CVD) method or an atomic layer deposition (ALD) method may also be used.

[0170] In the thermal CVD method, the pressure in the chamber is set to atmospheric pressure or reduced pressure, and the source gas and the oxidizing agent are simultaneously 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 set at atmospheric pressure or reduced pressure, and the source gas for the reaction is The gases are introduced into the chamber in sequence, and the film is formed by repeating the gas introduction sequence. For example, By switching each switching valve (also called high-speed valve), two or more types of raw materials can be 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 multiple source gases. At the same time or after this, an inert gas (argon, nitrogen, etc.) is introduced to 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 raw material gas is introduced. In addition, instead of introducing an inert gas, the first source gas is discharged by evacuation, and then the second source gas is introduced. The first source gas may be 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 several 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. This allows precise film thickness control, making it possible to fabricate minute transistors. It is suitable for fabrication.

[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. In step c, a mask is formed in a desired shape by a first patterning, and the mask is covered with the mask. This can be achieved by etching the areas that do not have a void (see FIG. 5(A)).

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

[0176] In addition, 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 pumped. Repeatedly introduce WF6 gas and H2 gas to form an initial tungsten film, then simultaneously 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 sputtering method, a CVD method, a vacuum deposition method, a PLD method, or the like. 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 deposition gases containing silicon include silane, disilane, and trisilane. , silane fluoride, etc. Oxidizing gases include oxygen, ozone, nitrous oxide, and nitrogen dioxide. There are elements such as

[0180] In addition, 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] In addition, the insulating film 305 and the insulating film 306 are formed by using a film forming apparatus that uses ALD. In the case of forming a hafnium chloride film, a liquid containing a solvent and a hafnium precursor compound (e.g., hafnium Hafnium alkoxide solution, typically tetrakisdimethylamidohafnium (TDMAH) Two types of gases are used: vaporized ozone (O3) as the source gas and ozone (O4) as the oxidizing agent. The chemical formula for tetrakisdimethylamidohafnium is Hf[N(CH3)2]4. Other examples of the material liquid include tetrakis(ethylmethylamido)hafnium.

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

[0183] In addition, the insulating film 305 and the insulating film 306 are formed by using a film forming apparatus that uses ALD. When forming a silicon oxynitride film, hexadichlorodisilane is adsorbed on the film-forming surface. It removes chlorine from the material 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 deposition method, or the like. The thin film can be formed by using ablation method, thermal CVD method, 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 mixture of rare gas and oxygen, the amount of oxygen relative to the rare gas is appropriately adjusted. It is preferable to increase the ratio of the nitrogen gas to 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 set to 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 may be reduced. A deposition gas having a temperature of -80°C or lower, preferably -100°C or lower, is used.

[0191] Using a deposition system that utilizes ALD, an oxide semiconductor film, such as an In-Ga-Zn-O film, can be formed. When depositing an InO layer, In(CH3)3 gas and O3 gas are introduced in sequence and repeatedly. Then, Ga(CH3)3 gas and O3 gas are introduced simultaneously to form a GaO layer, and 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. Also, by mixing these gases, In-Ga-O layers and A mixed compound layer such as an In-Zn-O layer or a Ga-Zn-O layer may 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 oxygen. Also, In(CH3)3 gas should be replaced with In(C 2H5)3 gas may be used. Also, instead of Ga(CH3)3 gas, Ga(C2H5 In(CH3)3 gas may be used. In(C2H5)3 gas may be used instead of In(CH3)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 covered with the The etching can be performed by etching the untreated area. Dry etching, wet etching, or a combination of both can be used. (See FIG. 5(C)).

[0193] After that, heat treatment is performed to remove the oxide semiconductor films 308a, 308b, and 308d. 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 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. to 400° C., preferably 320° C. to 370° C. By doing the following, it is possible to reduce warping and shrinkage of the board even in large area boards. and the yield is improved.

[0194] The heat treatment can be performed using an electric furnace, an RTA device, or the like. This allows heat treatment 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 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 less than 1 ppm, preferably less than 10 ppb), or rare gases (argon, helium The above-mentioned nitrogen, oxygen, ultra-dry air, or rare gas may be added to the water atmosphere. It is preferable that the material does not contain hydrogen, water, etc. Also, 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 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. Since this is possible, 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 to form conductive films 310a, 310b, and 311. In addition, the conductive films 310a, 310b, 310c, 310d, and 310e are formed. 10d and 310e form a mask by third patterning in a desired shape, and 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 310b 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)). The film can be formed by using a tarpaulin deposition 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 exposing it to the air. After the insulating film 311a is formed, the flow rate of the source gas is preferably set to 1000 μm without exposing the insulating film 311a to the atmosphere. At least one of the pressure, the high frequency power, and the substrate temperature is adjusted to continuously form the insulating film 311b. 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 moved to the oxide semiconductor films 308a, 308b, and 308d. The amount of oxygen vacancy in 08d can be reduced.

[0202] The insulating film 311a is formed by mixing an oxidizing gas with a deposition gas having a ratio of 20 to 100. 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 insulation film that contains nitrogen and has 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 deposition gases containing silicon include silane, disilane, and trisilane. Examples of oxidizing gases include oxygen, ozone, nitrous oxide, Nitrogen dioxide, etc.

[0204] By using the above conditions, an oxide insulating film that transmits oxygen is formed as the insulating film 311a. In addition, 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 oxide film placed in a processing chamber of a plasma CVD apparatus that has been evacuated to a vacuum. 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 to 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 Less than or equal to 0.25 W / cm 2 More than 0 .35W / cm 2 Silicon oxide or oxynitride is formed by supplying the following high frequency power. A silicon oxide 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 deposition gases containing silicon include silane, disilane, and trisilane. Examples of oxidizing gases include oxygen, ozone, nitrous oxide, Nitrogen dioxide, etc.

[0207] The insulating film 311b is formed under the following conditions: Supplying electric power increases the efficiency of decomposing the source gas in the plasma, and oxygen radicals increase. However, as the oxidation of the source gas progresses, the oxygen content in the insulating film 311b becomes smaller than the stoichiometric composition. However, when the substrate temperature is the deposition temperature of the insulating film 311b, Because the bond between silicon and oxygen is weak, some of the oxygen is released when heated. Oxidation that contains more oxygen than satisfies the stoichiometric composition and in which some of the oxygen is released by heating In addition, the oxide semiconductor films 308a, 308b, and 308d can be formed on the insulating film. In the step 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 providing high power. The insulating film 311b can be formed by using low-density high-frequency power.

[0208] In addition, in the film formation conditions of the insulating film 311b, the deposition property including 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. Generally speaking, the ESR measurement shows that the g value is 2.001, which is due to the dangling bond of silicon. The spin density of the signal that appears 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 As a result, an oxide insulating film containing nitrogen and having a small amount of defects can be formed. This can improve the reliability of the transistor.

[0209] Next, a heat treatment is performed. 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, the temperature is 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℃, there is no warping or shrinkage even in large area substrates. It is possible to reduce the amount of the defects, thereby improving the yield.

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

[0211] Heat treatment is carried out in a vacuum of 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.) In addition, 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 of the oxide semiconductor films 308a, 308b, and 308d. As a result, the amount of oxygen vacancies in the oxide semiconductor films 308a and 30 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. Then, the insulating film 313 having a function of bonding is formed and 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 are generated 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. It is possible to reduce the variation in the electrical characteristics of the transistors and to reduce the variation 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, so this heat treatment is 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 FIG. 08b, the surface facing the conductive films 304a and 304c functioning as gate electrodes is However, oxygen vacancies occur on the opposite surface of the insulating film 311b. By using an oxide insulating film containing more oxygen than silicon, The oxygen vacancies on the channel side can be repaired. The defects in 308a and 308b can be reduced, improving the reliability of the transistor. It can be raised.

[0216] Note that this 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 patterned in a desired shape by the fourth patterning. forming a mask by 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, for example, dry etching. It is preferable to etch the insulating film 311 by dry etching. Since the oxide semiconductor film 308d is exposed to plasma during the etching process, It is possible to increase the amount of oxygen vacancies in the film 308d. However, depending on 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 which wet etching is combined may also be used.

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

[0220] The insulating film 313 is made of a material that is free of impurities from the outside, such as oxygen, hydrogen, water, alkali metals, It is preferable to use a material that prevents an alkaline earth metal or the like from diffusing into the oxide semiconductor film. , and preferably contains hydrogen, typically an inorganic insulating material containing nitrogen, such as a 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., The membrane is 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 the oxide semiconductor film, hydrogen is bonded to oxygen, and electrons serving as carriers are generated. 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, the oxide semiconductor film is preferably formed at a high temperature. Oxygen is released from the oxide semiconductors used as 308a and 308b, and the carrier concentration increases. Since a phenomenon in which this occurs can occur, the temperature must be set at a level at which this 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 patterned in a desired shape by forming a mask by a fifth patterning process. This can be achieved by etching the uncovered areas (see FIG. 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 electrodes 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 onto 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 inkjet method or a printing method. This makes it possible to reduce the number of photomasks.

[0229] Next, the insulating film 305, the insulating film 306, and the insulating film 312 are formed by using the organic insulating film 317 as a mask. 3 and the insulating film 313 are etched to form openings that expose 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 seventh patterning mask. The mask can be formed by forming a mask and then etching the areas 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. The method of adding elements such as phosphorus, tin, antimony, and rare gas elements is ion doping. On the other hand, when an alkali metal or an alkaline earth metal is added to the oxide semiconductor film 308d, As a method for adding a 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 a substrate 342. and the alignment film 352.

[0236] First, a substrate 342 is prepared. The substrate 342 is made of the same material as that of 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 are formed of various materials by a printing method, an ink-jet method, They are formed at desired positions by an etching method using photolithography technology.

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

[0239] The insulating film 348 is made of an organic insulating material such as an acrylic resin, an epoxy resin, or a polyimide. By forming the insulating film 348, for example, the coloring film 34 It is possible to prevent impurities contained in the liquid crystal layer 321 from diffusing into the liquid crystal layer 321. However, the insulating film 348 is not necessarily required, and a structure in which the insulating film 348 is not formed may be used. Good too.

[0240] Next, a conductive film 350 is formed over the insulating film 348 (see FIG. 10C). The material shown 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 and 319a and the conductive film 350 formed on the substrate 342, The alignment film 320 and the alignment film 352 are formed. The alignment film 320 and the alignment film 352 are formed by a rubbing method. The substrate 302 and the substrate 342 are then sandwiched between them. 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 are bonded together, and then liquid crystal is 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 having 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 portion indicated by AB. The semiconductor device is characterized by having a transistor 102a.

[0247] The transistor 102a provided in the driving circuit section is connected to a gate electrode 302 provided on the substrate 302. A conductive film 304a functions as an electrode, and an 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 functioning as a source electrode and a drain electrode are in contact with the 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 a. 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 variation in characteristics, suppression of deterioration in GBT stress test, and under different drain voltages In addition, the oxide semiconductor film 308 can suppress the fluctuation in the on-state current rising voltage. In the case of a, the area in which 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 that is processed by etching or the like, the oxide semiconductor film is damaged during the processing. Defects are formed and the material is contaminated by impurities, so stresses such as electric fields When a material is provided with a potential, 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 portion is easily converted to n-type. The n-type end portion is connected to the source electrode and the drain electrode. When the conductive film 310a and the conductive film 310b are provided between the conductive films 310a and 310b, which function as electrodes, the n-type region However, the channel width is 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 exposed to the electric field of the conductive film 316d functioning as an electrode. Alternatively, the occurrence of a parasitic channel at the end including the side surface and the vicinity thereof is suppressed. As a result, a transistor with excellent electrical characteristics is obtained, in which the drain current increases sharply at the threshold voltage. Become 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 a diode as a transistor in the driving circuit section. The transistor is made of an Al-gate structure. As shown in Figure 12, The driver circuit shown in FIG. 1 includes a transistor 102a having a dual gate structure and a CD 10 may be used in the pixel portion having a dual-gate structure.

[0252] The transistor 103a is a conductive film that functions as a gate electrode and is provided over a substrate 302. 304c, insulating films 305 and 306 functioning as a 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 that functions as a gate electrode is formed on the film 53. The conductive film 316e is formed through an opening (FIG. In the second embodiment, the conductive film 304c 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 according to 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 alignment of the liquid crystal layer 321 caused by the electric field can be prevented. It can prevent good.

[0255] <Modification 3> In the second or third embodiment, the organic insulating film 317 is formed in the driving circuit section and the pixel section. However, as shown in FIG. 14, the liquid crystal display device having the organic insulating film 31 is formed only in the pixel portion. 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), a conductive film 316b shown in FIG. 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] In addition, as shown in FIG. 15, when the organic insulating film 317a is not provided in the driving circuit section, A conductive film 316d serving as a gate electrode of the transistor 102b having a double-gate structure is provided on the conductive film 316d. 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] (Embodiment 4) In this embodiment, a semiconductor device which is 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 310 includes conductive films 310d and 310e.

[0262] In addition, 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, alkali By introducing impurities such as lithium-earth metals or oxygen deficiencies, the electrical conductivity is improved, and the electrical conductivity is improved. Note that since the oxide semiconductor film has a light-transmitting property, the metal oxide film 308c also It has photochemical properties.

[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 capacitance element and increase the aperture ratio of the pixel. .

[0266] In addition, 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 via the inorganic insulating film 53 and the organic insulating film 317. That is, the conductive film 319 is spaced from the transistor 103. Since the distance is large, the potential of the conductive film 310d of the transistor 103 does not easily affect the conductive film 310d. As a result, the conductive film 319 can overlap with the transistor 103, and the pixel opening can be formed. You can increase your speaking rate.

[0267] The transistor 103 according to 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 effect of the above does not extend to the surface of the organic insulating film 317, and a positive charge is 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 void. 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 not easily affected. At the interface, a substantially positive bias is not applied, and the threshold voltage of the transistor is The fluctuation in voltage value 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, which diffuses 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 the variation in electrical characteristics. In addition, it has normally-off characteristics and is highly reliable. In addition, the organic insulating film can be formed by a printing method or a coating method. Since the film can be formed using a metal such as fluorine, the manufacturing time can be shortened. 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. The transistor is characterized by having a pair of conductive films 310f and 310g. The transistor 103 and the capacitor element 105 are connected to each other through a conductive film 319 that functions as a pixel electrode. It is characterized by the fact that

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

[0272] <Variation 2> In the display device shown in the fourth embodiment, depending on circumstances or circumstances, 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. As the circuit diagram of the pixel, FIG. 2 can be used as appropriate.

[0276] A 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 extending in a direction substantially perpendicular to the film (left and right direction in the figure). It functions as a signal line. The conductive film 310d extends in a direction (vertical direction in the figure) substantially perpendicular to the conductive film functioning as the scanning line. The mounting structure is elongated.

[0278] The transistor 103 includes a conductive film functioning as a scan line and a conductive film functioning as a signal line. The transistor 103 is provided in a region where the two intersect. 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 insulating 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 a light-transmitting property. has light-transmitting properties.

[0281] The conductive film 319 functioning as a pixel electrode is formed on the substrate 311 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. In other words, the transistor 103 and the capacitor element 1 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. In the embodiment, a driving circuit section (top view is 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 shown 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 , 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, the insulating film 305 and the insulating film 306 which 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 constitutes 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 A channel region formed on the insulating film 305 and insulating film 306 that function and the gate insulating film 51 The oxide semiconductor film 308b on which the conductive layer is formed functions as a source electrode and a drain electrode. The films 310d and 310e constitute the transistor 103. The oxide semiconductor film 308b , and are provided on the gate insulating film 51. In addition, inorganic insulating The insulating films 312 and 314, which are the film 53, are provided as protective films.

[0287] In addition, a metal oxide film 308c functions as one electrode, and an insulating film functions as a dielectric film. The capacitor 105 is formed by the film 314 and the conductive film 316b functioning as the other electrode. 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 0c is connected 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. The conductive films 310a, 310b, 310c, 310d, and 310e are formed at the same time. A common potential, a ground potential, or any other potential is applied to the conductive film 316b via the conductive film. .

[0292] Here, the components of the display device shown in FIG. 18 will be described below.

[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 a transistor in the pixel section.

[0294] An insulating film 305, an insulating film 306, and an insulating film 307 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 transistor of the driving circuit section. The gate insulating film 51 functions as the gate insulating film 51 of the transistor of the pixel section 11. do.

[0295] On the insulating film 306, oxide semiconductor films 308a and 308b and a metal oxide film 308c are formed. 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. The conductive film 304b is formed in a position overlapping 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. This makes it possible to increase the aperture ratio of the pixel 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 On the films 310a, 310b, 310c, 310d, and 310e, the following 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] In addition, conductive films 319 and 319a are formed on the organic insulating film 317. The conductive film 319a functions as a pixel electrode. 22A.) is electrically connected to the conductive film 310a through 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. This eliminates the need 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 for one That is, the number of manufacturing steps of the liquid crystal display device can be reduced. .

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

[0303] In addition, a colored film 346 is formed on the substrate 342. The light-shielding film 344 adjacent to the colored film 346 is a substrate 342. The light-shielding film 344 functions as a black matrix. 46 is not necessarily provided. For example, if the liquid crystal display device is monochrome, 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 planarizing the The function of the colored film 346 is to prevent impurities contained therein from diffusing into 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 conductive film 350 and the pixel electrode 9 a.

[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 formed by sealing the substrate 302 and the substrate 342 with a sealing material (not shown). The seal is placed between the two to prevent moisture from entering from the outside. In particular, it is preferable that the inorganic material is in contact with the inorganic material.

[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 in a liquid crystal display device shown in FIG. This will be explained with reference to FIG. 5 and FIG. 19 to FIG.

[0309] As in the second embodiment, a conductive film is formed on a substrate 302 through the steps shown in FIG. 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 a mask forming and etching process. 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 of 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, and the oxide semiconductor films 308a and 308 The hydrogen concentration and water concentration 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 shrinking of the board can be prevented even in large boards. This makes it possible to reduce the cost and improve the 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. Since this is possible, the heat treatment is not necessary.

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

[0313] Next, similarly to the second embodiment, the conductive film 309 is processed into a desired shape, so that the conductive film 3 10a, 310b, 310c, 310d, and 310e are formed. 310b, 310c, 310d, and 310e are patterns formed by a third patterning to a desired shape. The mask is then formed and the area not covered by the mask is etched away to form the Note that the conductive film 310e is a thin film having a thickness of 100 nm to 100 nm, and the oxide semiconductor film 308b is a thin film having a thickness of 100 nm to 100 nm. and is in contact with the oxide semiconductor film 308d.

[0314] Next, similarly to the second embodiment, the insulating film 306, the oxide semiconductor films 308a, 308b, and 08d, and the conductive films 310a, 310b, 310c, 310d, and 310e. 19C, an insulating film 311 is formed in which insulating films 311a and 311b are stacked. 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, a 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 distortion point, preferably 200° C. or higher and 450° C. or lower, more preferably 30 The temperature of the heat treatment is typically 300° C. to 450° C. 00℃ or less, preferably 320℃ to 370℃, It is possible to reduce warping and shrinkage of the substrate, improving yields.

[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 of the oxide semiconductor films 308a, 308b, and 308d. As a result, the amount of oxygen vacancies in the oxide semiconductor films 308a and 30 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. Then, the insulating film 313 having a function of bonding is formed and 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 are generated 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. It is possible to reduce the variation in the electrical characteristics of the transistors and to reduce the variation 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, so this heat treatment is It is not necessary.

[0319] Note that this 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 to form the insulating film 3 The insulating film 311 and the opening 362 are formed as desired. 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 3 is formed over the insulating film 312 and 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 patterned in a desired shape by forming a mask by a fifth patterning process. It can be formed by etching the uncovered areas (see FIG. 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 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 membranes 316b has an opening so that a portion of the membrane 316b is exposed.

[0326] Next, the insulating film 305, the insulating film 306, and the insulating film 312 are formed by using the organic insulating film 317 as a mask. 3 and the insulating film 313 are etched to form openings that expose the conductive film 304b. 364a, an opening 364b exposing the conductive film 310c, and an opening 364b exposing the conductive film 310e Form 364c (see FIG. 22(A)).

[0327] Next, similarly to the second embodiment, 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, so that the conductive film 3 The conductive films 319 and 319a are formed in a desired shape by applying 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 are formed on the substrate 342. 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 having a transistor different from that in Embodiment 4 will be described. This will be explained with reference to Figures 23 to 27.

[0335] The liquid crystal display device shown in FIG. 23 has a dual gate structure in the driving circuit portion indicated by AB. The semiconductor device is characterized by having 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 according to the sixth embodiment uses a diode as a transistor in a 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 having a dual gate structure and a CD 10 may be used in the pixel portion having a dual-gate structure.

[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 according to 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 alignment of the liquid crystal layer 321 caused by the electric field can be prevented. It can prevent good.

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

[0342] As shown in FIG. 27, when the organic insulating film 317a is not provided in the driving circuit section, A conductive film 316d serving as a gate electrode of the transistor 102b having a double-gate structure is provided on the conductive film 316d. 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. As an example, an organic EL element is used. Examples of the case are shown in Figs. 28, 29, 30, and 31. The device is a film of organic resin 371 such as acrylic resin, polyimide, and epoxy resin, and a film of organic resin 3 71 and a common electrode 375 provided on the EL layer 373. In addition, 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, In comparison, the process requires one more photomask, i.e., eight photomasks are used. A liquid crystal display device including a transistor and a capacitor will be described with reference to FIG.

[0346] The liquid crystal display device shown in FIG. 32 includes an opening 36 provided 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 conductive. It is characterized by being connected to the membrane 319.

[0347] In the liquid crystal display device described in this embodiment, a transistor 103 and a capacitor 105 are connected to each other. The opening for the pixel electrode 319 is connected to the transistor 103. That is, the conductive film 310e included in the transistor 103 and the capacitor An opening to which the conductive film 316b included in the capacitor 105 is connected and a The conductive film 310e overlaps with an opening to which 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 those described in any of Embodiments 2 to 7 will be described. 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 any of the 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 any of the 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, the insulating film 305 and the insulating film 306 which 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, 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 a 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 formed on the gate insulating film. the oxide semiconductor film 308b, the insulating film 392 covering the oxide semiconductor film 308b, and the insulating film 39 The oxide semiconductor film 308b is in contact with the oxide semiconductor film 308b through the opening 2, and the source electrode and the drain electrode are The functioning conductive films 310d and 310e constitute a transistor 103b. 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 316 b 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. The capacitor element 105 is formed of the insulating film 394 and the conductive film 316b functioning as an electrode. 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 material 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 It is possible to reduce the amount of oxygen vacancies contained in the oxide semiconductor layers 8a and 308b. It is preferable that the amount 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 an organic silane gas. By using an oxide insulating film, typically a silicon oxide film, it is possible to improve flatness. Note that the insulating film 314 is provided to allow the capacitor 105 to have a predetermined capacitance. 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. In addition, the oxide semiconductor films 308a and 308b are not damaged. The insulating film 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. In this way, the amount of oxygen vacancies in the oxide semiconductor films 308a and 308b can be reduced.

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

[0360] In addition, conductive films 319 and 319a are formed on the organic insulating film 317. The conductive film 319a functions as a pixel electrode. 36C ), and the conductive film 310b is electrically connected to the conductive film 310a through the opening 364b (see FIG. 36C ). ) 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 in a liquid crystal display device shown in FIG. This will be explained with reference to Figures 5, 34 to 36.

[0362] As in the first embodiment, a gate electrode is formed on a substrate 302 through the steps shown in FIG. 5(A) to FIG. 5(C). Conductive films 304a, 304b, and 304c function as gate electrodes, and The insulating film 305 and the insulating film 306 are formed of oxide semiconductor films 308a, 308b, and 308d. In this process, a first patterning and a second patterning are performed, The conductive films 304a, 304b, and 304c, the oxide semiconductor films 308a, 308b, and 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 the insulating film 311a.

[0364] Next, the insulating film 390 is processed into a desired shape to form 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 process. It can be formed by etching the areas not covered by the mask.

[0365] Next, a conductive film is formed over the oxide semiconductor films 308a and 308b and the insulating film 392. Through the same process as in the first embodiment, conductive films 310a, 310b, 310c, 310d, and 10e is formed (see FIG. 34(C)). Note that the conductive films 310a, 310b, and 310c , 310d, 310e, forming a mask by fourth patterning into a desired shape; The regions 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 are An insulating film 311 is formed thereon (see FIG. 35(A)).

[0367] Next, the insulating film 311 is processed into a desired shape to form an insulating film 311 having an 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. (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 316b is formed (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. The film can be formed by using a process similar to that of the film forming process. This step corresponds to the seventh patterning.

[0372] Next, the insulating film 305, the insulating film 306, and the insulating film 312 are formed by using the organic insulating film 317 as a mask. 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 that exposes the conductive film 316b and an opening 364d that exposes 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 (see FIG. 37). A mask is formed by turning, and the areas not covered by the mask are 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 can be 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. As an example, an organic EL element is used. Examples of the case where an organic EL element is used are shown in Figs. 38, 39, 40, 41, and 42. The display device is made of organic resin films 371 such as acrylic resin, polyimide, and epoxy resin. 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 necessary. Here, the transistor 103 is used for description.

[0378] In the transistor shown in FIG. 43, an oxide film is formed between the insulating film 306 and the conductive films 310d and 310e. A multi-layer 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. An 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 elements constituting the oxide semiconductor film 336a. The oxide semiconductor film 336b is formed of at least one of the elements constituting the oxide semiconductor film 336a. Since the oxide semiconductor film 336a is formed from the top, the oxide semiconductor film 336b is Therefore, the movement of carriers is not hindered at the interface. This increases the field effect mobility of the transistor.

[0381] The oxide semiconductor film 336b is typically an In—Ga oxide film, an In—Zn oxide film, or In-M-Zn oxide film (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn, etc.) or Hf), and the energy of the bottom of the conduction band is lower than that of the oxide semiconductor film 336a. Typically, the energy level of the oxide semiconductor film 336b is 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 organic semiconductor film 336a and the lower end of the conduction band of the organic semiconductor film 336b is 0.05 eV or more and 0.07 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 336a is 0.05 eV or more and 0.07 eV or more. 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, and thus has high carrier mobility (electron mobility). This is preferable.

[0383] The oxide semiconductor film 336b may be formed of Al, Ti, Ga, Y, Zr, La, Ce, Nd, or S. By having n or Hf in a higher atomic ratio than In, the following effects may be obtained. (1) The energy gap of the oxide semiconductor film 336b is increased. (3) 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 damaged by 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 When the sum of In and M is 100 atomic %, In is less than 50 atomic %. M is more than 50 atomic %, and more preferably In is less than 25 atomic %; Suppose M is greater than 75 atomic%.

[0385] The oxide semiconductor film 336a and the oxide semiconductor film 336b are made of an In-M-Zn oxide. (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn or Hf) Compared with the oxide semiconductor film 336a, the M (Al, Ti, G a, Y, Zr, La, Ce, Nd, Sn or Hf) have a large atomic ratio, typically The amount of the atoms contained in the oxide semiconductor film 336a is 1.5 times or more, and preferably 2 times The atomic ratio is more preferably 3 times or more higher.

[0386] The oxide semiconductor film 336a and the oxide semiconductor film 336b are made of an In-M-Zn oxide. (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn or Hf) 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 larger 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 may be formed of In:Ga:Zn=1:3:n (n is an integer between 2 and 8, 1:6:m (where 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 each calculated by subtracting the above atomic ratios from the atomic ratios as an error. The temperature of the oxide semiconductor film 336a is within the range of ±20%. When the content is Ga or more, CAAC-OS is easily formed, which is preferable.

[0388] The oxide semiconductor film 336b is formed by using an oxide semiconductor when forming the insulating film 312b to be formed later. 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. The thickness should be 50 nm or less.

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

[0391] Note that the oxide semiconductor films 336a and 336b each have an amorphous structure. region, microcrystalline region, polycrystalline region, CAAC-OS region, and single crystal 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 a finely crystalline structure region. Crystal structure region, polycrystalline structure region, CAAC-OS region, or single crystal structure region In some cases, the mixed film has a single layer structure having two or more regions. region, microcrystalline region, polycrystalline region, CAAC-OS region, single crystal region The insulating film may have a laminated structure of two or more of the above-mentioned regions.

[0392] Here, the oxide semiconductor film 336 is disposed between the oxide semiconductor film 336a and the insulating film 312a. Therefore, the insulating film 312a is provided between the oxide semiconductor film 336b and the insulating film 312a. Even if carrier traps are formed due to 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 to be covered. 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 threshold voltage of the transistor is changed due to 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 insulating film, and thus the fluctuation of the threshold voltage can be reduced. Cut.

[0393] In addition, the oxide semiconductor film 336b can block impurities from the outside. This makes it possible to 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 the amount of oxygen vacancies 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 designed so that there are no impurities that would form defect levels such as those shown in the figure. 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 exposing it to the air. Each chamber in the sputtering apparatus 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 pump (5×10 -7 Pa~1×10 -4 It is preferable to use a temperature of up to about 10 Pa. Alternatively, a turbo molecular pump and cold trap can be combined to separate the chamber from the exhaust system. It is preferable to prevent the backflow of gases into the bar, especially gases containing carbon or hydrogen. stomach.

[0396] In FIG. 43, the multilayer film 336 is made up of an oxide semiconductor film 336a and an oxide semiconductor film 3 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 semiconductor film 336b. In this case, the insulating film 306 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 size of the device 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 the present invention, one embodiment that can be applied to an oxide semiconductor film and a metal oxide film will be described. The structure of the oxide semiconductor film described here can be appropriately applied to a metal oxide film. <Structure of oxide semiconductors> The structure of an oxide semiconductor will be described below.

[0399] Oxide semiconductors are classified into single-crystal oxide semiconductors and 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, the oxide semiconductor is classified into an amorphous oxide semiconductor and a crystalline oxide semiconductor. Crystalline oxide semiconductors are classified into single crystal oxide semiconductors, CAAC- These include OS, polycrystalline oxide semiconductors, and microcrystalline oxide semiconductors.

[0401] <caac-os> First, let me explain about CAAC-OS. The oxide semiconductor has Axis Aligned Nanocrystals. It is also possible.

[0402] CAAC-OS is an oxide that has 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, in high-resolution TEM images, the boundaries between pellets, i.e., grain boundaries, are clearly visible. Therefore, it is difficult to clearly confirm the presence of the CAAC-OS at the grain boundaries. It can be said that the decrease in electron mobility caused by the above phenomenon is unlikely to occur.

[0404] The following describes 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 corrector function was used. In particular, this is called a Cs-corrected high-resolution TEM image. For example, a Cs-corrected high-resolution TEM image can be obtained by 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 region (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 called 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 FIG. 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 inclination 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 inclination occurs corresponds to the area 5161 shown in FIG.

[0408] FIG. 45(A) shows the C The s-corrected high-resolution TEM images are shown for regions (1), (2) and (3) in FIG. ) are enlarged Cs-corrected high-resolution TEM images shown in Fig. 45(B), Fig. 45(C), and Fig. 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 was analyzed by X-ray diffraction (XRD). We will explain AAC-OS. For example, CAAC-O with InGaZnO4 crystals When the out-of-plane structural analysis is performed on S, 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 has a c-axis orientation. It can be seen that the crystal has a c-axis oriented in a direction substantially perpendicular to the surface on which the crystal is formed or to the upper surface.

[0410] In addition, in the out-of-plane structural analysis of CAAC-OS, 2θ is 31 In addition to the peaks 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 contains crystals that do not have the c-axis orientation. The more preferable CAAC-OS is a structure obtained by the out-of-plane method. The analysis shows a peak at 2θ around 31° and no peak at 2θ around 36°.

[0411] On the other hand, in-pla, X-rays are incident on CAAC-OS from a direction nearly perpendicular to the c-axis. When the structure is analyzed by the NE method, a peak appears at 2θ of about 56°. This peak is I It is attributed to the (110) plane of the crystal of nGaZnO4. In the case of CAAC-OS, 2θ is set to 5 The sample was 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 FIG. 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 the b-axis is irregular.

[0412] Next, we will explain the CAAC-OS analyzed by electron diffraction. For CAAC-OS with ZnO4 crystals, a probe diameter of 300 nm was used 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 FIG. This diffraction pattern may appear due to the InGaZnO4 The spots due to the (009) plane of the crystal are included. Therefore, even by electron diffraction, 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 perpendicular to the sample surface, The diffraction pattern when an electron beam with a diameter of 300 nm was incident is shown in FIG. 7(B), a ring-shaped diffraction pattern is observed. Therefore, electron diffraction also It can be seen that the a-axis and b-axis of the pellets contained in CAAC-OS do not have any orientation. In addition, 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, etc.

[0413] In addition, the CAAC-OS is an oxide semiconductor with a low density of defect states. The defects include, for example, impurity-induced defects 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 can 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 have a higher acidity than metal elements that constitute oxide semiconductors. Elements with strong bonds to oxygen 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, an oxide semiconductor with a low density of defect states (few oxygen vacancies) has a low carrier density. Such an oxide semiconductor can be a highly pure intrinsic or substantially highly pure intrinsic oxide semiconductor. CAAC-OS is called an oxide semiconductor. It 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 Also, it is rare for the product to be pure or substantially pure. Oxide semiconductors have few carrier traps. The charge that is stored in the material takes a long time to be released and behaves like a fixed charge. Therefore, a transistor using an oxide semiconductor with a high impurity concentration and a high density of defect states is required. On the other hand, transistors using CAAC-OS can have unstable electrical characteristics. The resulting transistor has small fluctuations in electrical characteristics and is highly reliable.

[0417] In addition, because the density of defect states in CAAC-OS is low, the defects generated by light irradiation can be easily removed. Therefore, the carriers are less likely to be captured by the defect states. The electrical characteristics of a transistor vary little 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 in which a crystal part is not clearly observed and a region in which a crystal part is not clearly observed. The crystal part contained is 1 nm to 100 nm or 1 nm to 10 nm in size. In particular, fine crystals with sizes between 1 nm and 10 nm or between 1 nm and 3 nm are often The oxide semiconductor with nanocrystals is called nc-OS (nanocrystallin The nc-OS is called NC-Oxide Semiconductor. In some cases, the grain boundaries cannot be clearly seen 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 is used in microscopic regions (e.g., regions between 1 nm and 10 nm, especially regions between 1 nm and The atomic arrangement has periodicity 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 that uses X-rays with a diameter larger than that of the pellet for nc-OS may be used. When the structure was analyzed using the out-of-plane method, the crystal plane was not 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 are used that use an electron beam with a probe diameter close to the size of the pellet or smaller than the pellet. When the nc-OS is folded, spots are observed. In some cases, a bright area with a circular (ring-like) appearance 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) The oxide semiconductor or NANC (Non-Aligned Nanocrystal The semiconductor may also be referred to as an oxide semiconductor having a structure including a metal oxide layer.

[0422] The nc-OS is an oxide semiconductor with higher order than an amorphous oxide semiconductor. However, the density of defect states in the nc-OS is lower than that in the amorphous oxide semiconductor. In the case of S, there is no regularity in the crystal orientation between different pellets. Therefore, the 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 in the film is irregular and there are no crystalline parts. An example is an oxide semiconductor that has an amorphous state, such as quartz.

[0425] In the case of an amorphous oxide semiconductor, no crystalline parts can be confirmed in a high-resolution TEM image.

[0426] When the structure of amorphous oxide semiconductors is analyzed using an XRD device, out-of-p In the lane analysis, no peaks indicating crystal planes were detected. When electron diffraction is performed on a conductor, a halo pattern is observed. When nanobeam electron diffraction was performed on the specimen, no spots were observed, only a halo pattern was observed. 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. In addition, the distance between the nearest neighbors or the second nearest neighbors is called the structure. A structure that has order at the interface and no 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-crystalline oxide semiconductor. In addition, it cannot be called an crystalline oxide semiconductor. Amorphous oxide semiconductors cannot be called amorphous oxide semiconductors. For example, CAAC-OS and nc-OS can be 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 (alumina-like oxide semiconductor). ike OS:amorphous-like Oxide Semiconducto It is called r).

[0429] In a-like OS, voids are observed in high-resolution TEM images. In addition, crystals may be clearly visible in high-resolution TEM images. and regions where no crystalline portion can be confirmed.

[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 change in structure due to 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 obtained. It can be seen that all the materials have crystalline parts.

[0433] The determination of which part is 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 layered 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 between the crystals is 0.28 nm to 0.30 nm are considered to be crystal parts of InGaZnO4. The lattice fringes correspond to the ab plane of the InGaZnO4 crystal.

[0434] Figure 48 shows an example of the average size of the crystal parts (22 to 45 places) of each sample. However, the length of the lattice fringes is the size of the crystal part. It can be seen that the crystalline part of the ke OS grows in size according to the cumulative dose of electron irradiation. Specifically, as shown by (1) in Figure 48, the initial TEM observation showed a size of about 1.2 nm. The crystal part (also called the initial nucleus), which 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 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 crystals within the range of As shown in (2) and (3) in Figure 48, 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] Thus, in a-like OS, the growth of crystals can be observed by electron irradiation. On the other hand, in the case of nc-OS and CAAC-OS, the growth of the crystals due to electron irradiation is almost nonexistent. In other words, a-like OS is not seen as a nc-OS or CAAC-OS. It is clear that it has an unstable structure compared to the OS.

[0436] In addition, because of the porosity, a-like OS is more difficult to treat than nc-OS and CAAC-OS. Specifically, the density of the a-like OS is The density of the nc-OS and the CAA 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 5.0g / 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 of the same composition do not exist. In such cases, crystals of different compositions may be used in any ratio. By combining single crystals of the desired composition, the density equivalent to that of a single crystal of the desired composition 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 the size of the single crystal by combining different types of single crystals.

[0439] As described above, oxide semiconductors have various structures and each structure 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 having 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 in which a CAAC-OS film is formed by a sputtering method. FIG. 1 is a schematic diagram of the inside of a membrane chamber.

[0442] The target 5130 is attached to a backing plate. A plurality of magnets are disposed at positions facing the target 5130 through the magnets. The magnetic field is generated by a number of magnets. The magnetic field of the magnets is used to increase the deposition speed. 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 (TS distance) is preferably 0.01 m or more and 1 m or less. The deposition chamber is mostly filled with deposition gas (e.g., oxygen, argon, or a mixture containing 5% or more by volume of oxygen) and The pressure is controlled to be 1 Pa or more and 100 Pa or less, preferably 0.1 Pa or more and 10 Pa or less. By applying a certain voltage to the target 5130, a discharge starts and a 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 ion 5101 is, for example, an oxygen cation (O + ) and argon cations ( Ar + ) etc.

[0444] Here, the target 5130 has a polycrystalline structure having multiple crystal grains, The crystal grains include cleavage planes. FIG. 50(A) shows an example of a target 5130. The crystal structure of InGaZnO4 is shown in Fig. 50(A). This is the structure of InGaZnO4 crystals observed from the outside. In the Ga-Zn-O layers, the oxygen atoms in each layer are arranged in close proximity. The negative charge of the oxygen atom causes the two adjacent Repulsion occurs between the Ga-Zn-O layers. As a result, the InGaZnO4 crystals are The cleavage plane is 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 cleavage plane is then accelerated and collides with the target 5130. At this time, flat or planar particles are generated from the cleavage plane. Pellet 5100a and pellet 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, 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 having a plate-like or pellet-like shape. The term pellets refers to flat or pellet-shaped sputter particles such as pellet 5100b. The planar shape of the pellet 5100 is not limited to a triangle or a hexagon, but may be any shape, e.g. For example, a shape may be formed by combining multiple triangles. In some cases, the shape may be a quadrilateral (for example, a rhombus) made up of two joined sides.

[0447] The thickness of the pellet 5100 is determined according to the type of deposition gas. The reason will be explained later. It is preferable that the thickness of the pellet 5100 is uniform. A pellet shape with no lumps is preferable to a thick cube shape. The thickness of the 5100 is 0.4 nm to 1 nm, preferably 0.6 nm to 0.8 nm. For example, the pellet 5100 has a width of 1 nm or more and 3 nm or less. The diameter of the pellet 5100 is 1.2 nm or more and 2.5 nm or less. For example, the target 5 having In-Ga-Zn oxide corresponds to the initial nucleus described in . When ions 5101 are bombarded with the Ga-Zn-O layer 130, as shown in FIG. A pellet 5100 having three layers, an In-O layer and a Ga-Zn-O layer, is peeled off. FIG. 1C shows the structure of the exfoliated pellet 5100 observed from a direction parallel to the c-axis. The RET5100 is a nano-sized wafer with two Ga-Zn-O layers and an In-O layer. This 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, for example, have negatively charged oxygen atoms located on its sides. The sides of the particles have the same polarity of charge, so the charges repel each other, forming a flat or pentamorphic 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 be possible that the pellet 5100 may be irradiated with the plasma. The area where the atoms grow by bonding with indium, gallium, zinc, and oxygen atoms. 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 Since the growth of 5100 is difficult, the OS becomes nc-OS (see Figure 49(B)). Since the film can be formed at a high speed, nc-OS can be formed even on a large substrate (5120). In order to grow the pellet 5100 in plasma, a sputtering method is used. It is effective to increase the film formation power in the pellet 5. 100 structures can be stabilized.

[0449] As shown in FIG. 49(A) and FIG. 49(B), for example, a 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 the 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. In addition, a vertical 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 electrodes 130, the electric field from the substrate 5120 to the target 5130 Therefore, the pellet 5100 is disposed on the upper surface of the substrate 5120 in the following manner: The magnetic field and the electric current act on the object, creating a force (Lorentz force). This is what Fleming This can be understood by the left-hand rule.

[0450] The pellet 5100 has a large mass compared to 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 the substrate 5120 must be 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. At the top surface of the plate 5120, a magnetic field parallel to the top surface of the substrate 5120 At least 1.5 times, preferably at least 2 times, more preferably at least 3 times the magnetic field perpendicular to the top surface. It is preferable to provide an area where the thickness is 5 times or more.

[0451] At this time, the magnet and the substrate 5120 move or rotate relatively. 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. 0 and the substrate 5120, the resistance due to friction 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 pellet 5100 reaches its side surface, the sides of the pellet 5100 are joined together. The oxygen atom on the side of 00 is removed. The removed oxygen atom causes the Since oxygen vacancies may be filled, the CAAC-OS has a low density of defect states. The temperature of the upper surface of the plate 5120 is, for example, 100° C. or more and less than 500° C., 150° C. or more and 450° C. The temperature may be set to 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 relieved. Pellet 5100 is almost single crystal. Even if the pellets 5100 are heated after being bonded to each other, the pellets 5100 themselves do not expand. Therefore, the gaps between the pellets 5100 widen, and the crystals 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 pellets are made of nano-crystals, and the aggregates resemble bricks or blocks stacked together. In addition, there are no grain boundaries between the pellets 5100. Heating during and after film formation, or bending, can cause deformation such as shrinkage in CAAC-OS. Even if the deformation occurs, it is possible to relieve the local stress or release the strain. This structure is suitable for use in flexible semiconductor devices. The result is an arrangement in which Ret 5100 (nanocrystals) are randomly stacked.

[0455] When the target 5130 is sputtered by ions 5101, not only the pellet 5100 but also Zinc oxide may peel off. 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. A schematic cross-sectional view is shown in Figure 51.

[0456] As shown in FIG. 51(A), a pellet 5105a and a pellet Here, the pellets 5105a and 5105b are deposited. The pellets 5105c and 5105c are arranged so that their sides are in contact with each other. After being deposited on the pellet 5105b, the pellet 510 slides on the pellet 5105b. In another aspect of FIG. 05a, 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 condensing the pellet 5105a2. 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 pellet 5105b. It also slides toward the other side of the pellet 5105c. The pellet 5105 e 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 is in contact with 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 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 that occurred after deposition.

[0461] In addition, the gaps between the pellets become extremely small, so that one large pellet is formed. One large pellet may have a single crystal structure. For example, The size is 10 nm or more and 200 nm or less, 15 nm or more and 100 nm or less, as viewed from the top. In some cases, the size of the transistors used is between 20nm and 50nm. In an oxide semiconductor, a channel formation region may be contained within one large pellet. That is, a region having a single crystal structure can be used as a channel forming region. As the gap grows, 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 considered that the pellet 5100 is deposited on the substrate 5120. CAAC-OS can be deposited even on a surface that 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 achieve uniform growth even on large glass substrates. For example, 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 CAAC-OS is to be formed is uneven, 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 pellet 5100 has a uniform thickness, it is flat and has a uniform thickness. A layer with high crystallinity is formed. Then, the layer is stacked in n steps (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 unevenness, 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. Since the surface of the pellet 5100 is uneven, gaps tend to form between the pellets 5100 in the CAAC-OS. However, even in this case, intermolecular forces act between the pellets 5100, causing unevenness. Even if the pellets are arranged in a way that the gaps between them are as small as possible. It is possible to obtain a CAAC-OS having high crystallinity.

[0466] Since the CAAC-OS film is formed by such a model, the sputtered particles are distributed evenly throughout the film. It is preferable that the sputtered particles are in the form of thick pellets. 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 shows that a highly crystalline film can be formed even on a substrate surface having an amorphous structure. Thus, a CAAC-OS having the above properties can be obtained.

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

[0469] First, the cleavage plane of the target will be explained with reference to FIG. The crystal structure of nO4 is shown in Fig. 52(A). Note that the c-axis is oriented upward and parallel to the b-axis. FIG. 52(B) shows the structure of the InGaZnO4 crystal when observed from the c The structure of an InGaZnO4 crystal observed from a direction parallel to the axis is shown.

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

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

[0472] Based on the crystal structure of InGaZnO4 shown in Figure 52, the first plane, the second plane, and the third plane A structure cleaved at either the first or fourth plane was created, and the cell size was fixed and structural optimization calculations were performed. Here, the first plane is a crystal plane between the Ga-Zn-O layer and the In-O layer, ( 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 parallel to the (110) plane (see Figure 52(A)). (See Figure 52(B)). The fourth plane is the (100) plane (or the bc plane). 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. The difference between the energy of the structure and the energy of the initial structure is divided by the area of ​​the cleavage plane. The cleavage energy, which is a measure of the ease of cleavage on each plane, is calculated. Energy is the kinetic energy of the electrons and the interatomic and atomic energies of the atoms and electrons contained in the structure. This energy takes into account interactions between electrons and between electrons.

[0474] The calculation results show that the cleavage energy of the first face 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 the lowest at the Ga-Zn-O layer and the Ga-Zn-O layer. It can be seen that the plane (cleavage plane) between the two is the easiest to cleave. When referred to as a cleavage plane, 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 a target, the highest cleavage energy is obtained. The wafer-like units (which we call pellets) cleaved from the lower surface of the ghee are the best. It is thought that the InGaZnO4 pellets will fly out in small units. The result is three layers: 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 a (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 determine the homologous structure of 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-atom GaN crystal is shown in FIG. 53(A), and the top view structure is shown in FIG. 53(B). The fixed layer shown in (A) is a layer in which the arrangement of atoms is fixed so that the positions do 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 Ltd.'s Materials Explorer 5 was used. The initial temperature is 300K, the cell size is constant, and the time step size is 0.01f. The time is set to femtoseconds and the number of steps is set to 10 million. In the calculation, under these conditions, 300 eV of energy is applied, and atoms are injected into the cell from a direction perpendicular to the ab plane of the InGaZnO4 crystal. is incident.

[0481] FIG. 54(A) shows the state where argon is introduced into the cell having the InGaZnO4 crystal shown in FIG. Fig. 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 injected into the hole. A part of the fixing layer shown in (A) is omitted.

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

[0483] On the other hand, from FIG. 54(B), within 99.9 picoseconds after oxygen enters the cell, the It can be seen that the cracks originate 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 having a homologous structure When atoms (ions) collide with the InGaZnO4 crystal, it cleaves along the second plane, It can be seen that flat particles (pellets) peel 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 areas in the matrix can be repaired by reacting oxygen with the defects caused by the damage. There are cases.

[0486] Therefore, we investigated whether the pellet size differs depending on the type of atoms 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 from 0 picoseconds to 0.3 picoseconds after irradiation is shown in Fig. 55(A) corresponds to the period between FIG. 53 and FIG. 54(A).

[0488] 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 out. Therefore, the crystals of InGaZnO4 are When argon is bombarded against the target, a turtle appears on the second surface (second) in Figure 53(A). It is thought that cracks will occur.

[0489] In addition, 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 out. Therefore, the target containing InGaZnO4 crystals When oxygen is bombarded, it is believed that a crack will appear on the second surface (first surface) in FIG. 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 material peels off from the surface.

[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). Here, 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 the 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 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 Bi'v' Ga The relationship can be expressed as equation (3).

[0496]

number

[0497] From equations (1), (2) and (3), v Ga If you set it to 0, argon or oxygen The velocity of the gallium after the collision is v' Ga can be expressed as equation (4).

[0498]

number

[0499] In formula (4), m A Substitute the mass of argon or the mass of oxygen into and calculate the mass of each atom. Compare the velocity of gallium after it is hit by argon and oxygen. When the number of collisions is the same, the collision with argon is 1.2 times greater than the collision with oxygen. The speed of gallium is four times faster than that of the gallium. Therefore, the energy of gallium is also When Gon collides, the velocity is squared higher than when oxygen collides.

[0500] When argon was bombarded, the amount of gallium after the bombardment was greater than when oxygen was bombarded. Therefore, when argon is collided, It is believed that cracks occurred at deeper positions in the case of bombardment with oxygen than in the case of bombardment with oxygen.

[0501] From the above calculations, it was found that the target containing InGaZnO4 crystals with a homologous structure When sputtering, it peels off from the cleavage plane and forms a pellet. Sputtering areas of other structures on the target that do not have a surface will not form pellets. The sputtered particles are formed in a size on the atomic level, which is smaller than the size of the sputtered particles. Because it is smaller than a pellet, it can be vacuum pumped through the sputtering device. Therefore, the crystal of InGaZnO4 with homologous structure When a target containing Zn 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 for forming a C-OS film shown in Figure 49(A) is reasonable.

[0502] The density of the CAAC-OS film thus formed 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 The density of CAAC-OS, which has a similar atomic ratio, is 6.3 g / c m 3 It will be about that amount.

[0503] Figure 56 shows the In-Ga-Zn oxide film, which is a CAAC-OS film formed by sputtering. (See FIG. 56(A)) and the cross section of the target (See FIG. 56(B)). The atomic arrangement is shown. The atomic arrangement was observed using high-angle annular dark-field scanning transmission electron microscopy (HA 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), which 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 deposition model in Figure 49(A), the crystal structure of the target is transformed. The image shows that a CAAC-OS film is formed.

[0505] <Oxide Semiconductor Film and Metal Oxide Film> An oxide semiconductor film such as the oxide semiconductor film 308b shown in FIG. A film formed of the above (hereinafter referred to as an oxide semiconductor film (OS)) and a film used as an electrode of a capacitor element are 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 measurement temperature, and the vertical axis shows the resistivity. The measurement results of the oxide semiconductor film (OS) are indicated by circles, and the measurement results of the oxide conductor film (OC) are indicated by circles. The measured results are indicated by square marks.

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

[0507] The sample containing the oxide conductor (OC) was prepared by depositing an In:Ga atomic ratio on a glass substrate. A sputtering method was used with a sputtering target of Zn=1:1:1 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 was then deposited by plasma CVD. It was prepared by forming a con film.

[0508] As can be seen from FIG. 57, the temperature dependence of resistivity in an 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 change in resistivity of the oxide conductor film (OC) at 290K or less is less than ±20%. Alternatively, the rate of change in resistivity from 150K to 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. For this reason, the oxide conductor film is used as the electric field of resistor elements, wiring, and capacitor elements. The electrode can be used for a pixel electrode, a common electrode, 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) at which the image signal or other electric signals 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, so that The liquid crystal display device can perform display by 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 input 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 data. In other words, the refresh rate is reduced. This is the driving mode.

[0512] The display of moving images is performed in the first driving mode. The display of still images is performed in the second driving mode. Since the image data does not change, there is no need to rewrite the data for each frame. When displaying still images, the second driving mode can be used to eliminate screen flicker. At the same time, power consumption can be reduced.

[0513] In addition, the liquid crystal element applied to the liquid crystal display device of the present embodiment is a capacitance element having a large area. Therefore, the time for which the potential of the pixel electrode is held is It is possible to lengthen the display and apply a driving mode that reduces the refresh rate. Furthermore, in the case where 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 better prevent the perception of image flicker by the viewer. As a result, the display quality can be improved.

[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. Nervous fatigue is caused by prolonged use of the eyes. By continuing to look at the light-emitting or flashing screen of an LCD display, the brightness of the screen can damage the retina, nerves, and brain. Fatigue in the muscular system stimulates and tires the ciliary muscles, which are used for focusing. It tires the muscles by overworking them.

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

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

[0518] In other words, as shown in FIG. 58(B), for example, an image can be rewritten once every five seconds. This allows users to see the same image as much as possible, and reduces screen flickering that is visible to the user. This reduces the stimulation of the retina, nerves and brain of the user's eyes, 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, a structural example of an electronic device to which a 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 with reference to FIG.

[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, A display panel 8006, a backlight unit 8007, a frame 8009, a printed circuit board The backlight unit 8007, the battery 8011, and the LCD panel 8012 are also included. 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 appropriate to match the size of 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 make it into an optical touch panel. Alternatively, a touch sensor electrode may be provided in each pixel of the display panel 8006 to realize a capacitive touch sensor. It is also possible to use it as a touch panel.

[0526] The backlight unit 8007 includes a light source 8008. Alternatively, the light diffusing plate may be provided at the end of the light receiving unit 8007.

[0527] The frame 8009 protects the display panel 8006 and also supports 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 frame. 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] The electronic device may be, for example, a television device (television or television receiver) (also called "computer monitors"), digital cameras, digital video cameras, etc. digital photo frames, mobile phones (also called mobile phones or mobile phone devices), These include large game machines such as small game machines, portable information terminals, audio playback devices, and pachinko machines. can be.

[0532] FIG. 60(A) shows a portable information terminal, which includes a main body 1001, a housing 1002, a display unit 10 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 units 1003a and 1003b, It is 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 Ability to manipulate or edit displayed information, processed by various software (programs) In addition, the rear and side of the housing may be provided with terminals for external connection. It may also be configured to include a connector (such as an earphone jack or USB port) and a recording medium insertion section.

[0534] The portable information terminal shown in FIG. 60(A) is configured to be capable of wirelessly transmitting and receiving information. The desired book data can be purchased and downloaded wirelessly from an electronic book server. It is also possible to configure the device to perform this function.

[0535] FIG. 60(B) shows a portable music player. The main body 1021 has a display unit 1023 and an earphone. The device has a fixing part 1022 for mounting to an external device, a speaker, an operation button 1024, and an external memory slot. The transistors described in the above embodiment are switched By preparing 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 FIG. 60(B) is equipped with an antenna, microphone function, and wireless function. If you carry it with you 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 includes a display panel 1032, a speaker 1033, a microphone, and the like. 1034, a pointing device 1036, a camera 1037, an external connection terminal 103 The housing 1030 also includes a solar cell 1040 for charging the mobile phone. , an external memory slot 1041, etc. Also, the antenna is provided inside the housing 1031. The transistor described in the above embodiment is applied to the display panel 1032. This makes it possible to provide a highly reliable mobile phone.

[0538] The display panel 1032 is equipped with a touch panel, and in FIG. The operation keys 1035 are indicated by dotted lines. It also implements a boost circuit to boost the voltage supplied to each circuit to the voltage required.

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

[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, etc. 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 function, TV reception function, 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, a highly reliable television device 1050 can be obtained.

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

[0544] The television device 1050 includes a receiver, a modem, and the like. This allows reception of general television broadcasts, and can also be used for wired or wireless reception via a modem. By connecting to a network, communication can be one-way (sender to receiver) or two-way It is also possible to communicate information in both directions (between sender and 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 a It can be connected to any type of cable, enabling data communication with a personal computer, etc. In the storage medium playback and 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 and the CPU, power consumption can be reduced sufficiently. This results in a highly reliable television apparatus 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

[Claim 1] A transistor on the substrate; an inorganic insulating film in contact with the transistor; an organic insulating film in contact with the inorganic insulating film; a capacitance element electrically connected to the transistor; a pixel electrode formed on the organic insulating film and electrically connected to the transistor; The transistor comprises: a gate electrode on the substrate; an oxide semiconductor film overlapping the gate electrode; a gate insulating film in contact with one surface of the oxide semiconductor film; a pair of conductive films in contact with the oxide semiconductor film, The capacitance element includes a metal oxide film on the gate insulating film, The inorganic insulating film; a first light-transmitting conductive film on the inorganic insulating film, the pixel electrode is formed using a second light-transmitting conductive film and is in contact with one of the pair of conductive films and the first light-transmitting conductive film.

Images