Liquid crystal display device

Abstract

To provide a semiconductor device with driving circuit, having high opening ratio, including a capacitive element with increased charge capacitance, and consuming less power.SOLUTION: The semiconductor device comprises: a driving circuit including a first transistor with gate electrodes above and below a semiconductor film in an overlapping manner; a pixel having a second transistor including the semiconductor film; a capacitive element including a dielectric film between a pair of electrodes provided in the pixel; and a capacitance line electrically connected to one electrode of the pair of electrodes. The gate electrode provided on the semiconductor film of the first transistor is electrically connected to the capacitance line.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The invention disclosed in this specification and elsewhere relates to a semiconductor device. [Background technology]

[0002] In recent years, flat panel displays such as liquid crystal displays (LCDs) have become widely used. In a display device such as a flat panel display, the pixels are arranged in the row and column directions. In the pixel, a transistor which is a switching element and an electric a liquid crystal element connected in series to the liquid crystal element, and a capacitance element connected in parallel to the liquid crystal element. do.

[0003] The semiconductor material constituting the semiconductor film of the transistor is amorphous (non-crystalline) Silicon semiconductors such as silicon or polysilicon (polycrystalline) are widely used.

[0004] Metal oxides that exhibit semiconductor properties (hereinafter referred to as oxide semiconductors) are used in transistors. For example, zinc oxide or In-Ga-Zn-based oxide Techniques for fabricating transistors using nitride semiconductors have been disclosed (Patent Document 1 and Patent Document 2). (See patent document 2). [Prior art documents] [Patent documents]

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

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

[0007] In addition, the larger the capacitance value of the capacitance element, the more the liquid crystal element will The period during which the orientation of the crystal molecules can be kept constant can be extended. In a display device, the ability to extend this period reduces the number of times image data is rewritten. This allows for a reduction in power consumption.

[0008] In order to increase the charge capacity of the capacitance element, the area occupied by the capacitance element must be increased. However, there is a way to increase the area where the pair of electrodes overlap. In a display device, a light-shielding conductive film is used to increase the area where a pair of electrodes overlap. If the area of ​​the conductive film is increased, the aperture ratio of the pixel decreases, and the display quality of the image deteriorates.

[0009] In addition, a process for forming a transistor in a pixel of a display device can be used to form a display device. The transistors constituting the drive circuit of the device can be formed. The transistors that operate at a higher speed than the transistors provided in the pixels are As a transistor constituting a driver circuit, a semiconductor film is overlapped with the semiconductor film. A transistor with gate electrodes on the top and bottom of the ) can improve the operating speed of the transistor. The application of a dual gate transistor means that a semiconductor film is overlapped with the semiconductor film. A structure (wiring, terminals, power supply, etc.) is required above and below the film to control the potential of the gate electrode. This increases the power consumption of the driver circuit, and may also increase the power consumption of the display device.

[0010] In view of the above, one embodiment of the present invention is to provide a semiconductor device having a driver circuit with a high aperture ratio and The object of the present invention is to provide a semiconductor device having a capacitance element capable of increasing the charge capacity. Another embodiment of the present invention is a semiconductor device including a driver circuit, in which an aperture ratio is Semiconductor device having a capacitance element capable of increasing charge capacity and reducing power consumption One of the objectives is to provide a facility for [Means for solving the problem]

[0011] In view of the above-described problems, one embodiment of the present invention provides a semiconductor film having gate electrodes formed above and below the semiconductor film. a driving circuit including a first transistor having a gate electrode; and a second transistor including a semiconductor film. a pixel including a capacitor, and a capacitance element in which a dielectric film is provided between a pair of electrodes provided in the pixel; and a capacitance line electrically connected to one of the pair of electrodes, A gate electrode provided on the semiconductor film of the transistor is electrically connected to a capacitance line. The semiconductor device is characterized in that

[0012] More specifically, one embodiment of the present invention is a method for manufacturing a semiconductor film by forming a semiconductor film on the upper and lower sides of the semiconductor film. A driving circuit includes a first transistor having a gate electrode, and a second transistor includes a semiconductor film. A capacitor is a capacitor in which a dielectric film is provided between a pixel including a transistor and a pair of electrodes provided in the pixel. an element, a capacitance line electrically connected to one of the pair of electrodes, and a second transformer; a pixel electrode electrically connected to the first transistor, the pixel electrode being provided on the semiconductor film of the first transistor; The gate electrode and the capacitance line are electrically connected to each other, and the capacitance element is The semiconductor film is formed on the same surface as the semiconductor film of the transistor, and the semiconductor film is The pixel electrode functions as one of the pair of electrodes, and the lead electrode functions as the other of the pair of electrodes. a semiconductor film formed on the second transistor; It is a conductor device.

[0013] In the capacitor, one electrode is formed of a light-transmitting semiconductor film of the second transistor. the other electrode of the light-transmitting pixel transistor is electrically connected to the second transistor. The dielectric film is formed on the light-transmitting semiconductor film of the second transistor. In other words, since the capacitor element has light-transmitting properties, It can be formed in a large area in a region other than where the transistor is formed. Therefore, a semiconductor device with an increased aperture ratio and an increased charge capacity can be obtained. Furthermore, by improving the aperture ratio, a semiconductor device with excellent display quality can be obtained.

[0014] In addition, like the first transistor, a semiconductor film is provided on the channel formation region. The gate electrode (hereinafter referred to as the back gate electrode) is electrically connected to one electrode of the capacitor element. By electrically connecting to the connected capacitance line, the potential of the capacitance line can be controlled. The potential of the back gate electrode can be controlled. The configuration for controlling the first transistor can be omitted, and the first transistor can be a dual gate transistor. In other words, the operation speed of the drive circuit can be increased. When the first transistor is driven as a gate transistor, Therefore, it is possible to achieve both an increase in operating speed and a reduction in power consumption. Therefore, a semiconductor device that can be manufactured using the semiconductor device can be obtained.

[0015] The light-transmitting semiconductor film can be formed using an oxide semiconductor. Semiconductors have a large energy gap of 3.0 eV or more, and have high transmittance to visible light. Hereinafter, a light-transmitting semiconductor film is simply referred to as an oxide semiconductor film. Therefore, the second transistor is a transistor using an oxide semiconductor film. One electrode of the capacitor is an oxide semiconductor film.

[0016] The light-transmitting capacitor element can be manufactured by utilizing the formation process of the second transistor. One electrode of the capacitor is formed by using the step of forming the oxide semiconductor film of the second transistor. The dielectric film of the capacitor element can be formed by using an insulating film provided on the semiconductor film of the second transistor. The other electrode of the capacitor element is electrically connected to the second transistor. A process for forming pixel electrodes that are connected to the substrate can be utilized.

[0017] The first transistor constituting the driver circuit can also be formed using the same process as the second transistor. The back gate electrode of the first transistor can be formed by It can be formed by utilizing the process for forming the electrically connected pixel electrode. The gate electrode is a conductive film made of the same material as the pixel electrode.

[0018] In the above, the insulating film provided over the oxide semiconductor film of the second transistor is an oxide insulating film. By forming a laminated structure of the dielectric film and the nitride insulating film, the dielectric film can be formed by laminating the oxide insulating film and the nitride insulating film. The structure can be:

[0019] The insulating film provided on the semiconductor film of the second transistor is an oxide insulating film and a nitride insulating film. When a laminated film structure is used, the oxide insulating film is removed only from the region above the capacitor element. The dielectric film of the element can be made into a single layer structure consisting of only the nitride insulating film. The nitride insulating film is in contact with the oxide semiconductor film which functions as one electrode of the capacitor. When the nitride insulating film and the oxide semiconductor film are in contact with each other, a defect level is formed at the interface between the nitride insulating film and the oxide semiconductor film. and / or the nitride insulating film is formed by plasma CVD or spat When a semiconductor film is formed by a pulverizing method, the semiconductor film is exposed to plasma, and oxygen vacancies are generated. Furthermore, nitrogen and / or hydrogen contained in the nitride insulating film migrate to the semiconductor film. When hydrogen contained in the nitride insulating film enters the level or oxygen vacancy, electrons, which act as carriers, are generated. As a result, the conductivity of the semiconductor film increases, it becomes n-type, and it becomes a conductive film. The oxide semiconductor film can be easily and sufficiently made to function as one electrode of a capacitor. In addition, since the thickness of the dielectric film can be made thin, the charge capacity of the capacitance element can be reduced. The amount can be increased.

[0020] One embodiment of the present invention is a first semiconductor device having gate electrodes above and below a semiconductor film overlapping the semiconductor film. a driver circuit including the transistor, a pixel including a second transistor including a semiconductor film, and a capacitance element having a pair of electrodes and a dielectric film provided between the electrodes; a capacitance line electrically connected to one electrode of the first transistor and a capacitance line electrically connected to the second transistor; a pixel electrode formed on the first transistor; and a gate electrode provided on the semiconductor film of the first transistor. and a capacitance line are electrically connected to each other, and in at least the second transistor, an insulating film having a stacked structure of an insulating oxide film and an insulating nitride film is provided on the semiconductor film; the capacitor element has a semiconductor film formed on the same surface as the semiconductor film of the second transistor; The semiconductor film functions as one of a pair of electrodes, and the pixel electrode functions as the other of the pair of electrodes. The semiconductor device is characterized in that the dielectric film functions as a pole and is a nitride insulating film.

[0021] The insulating film provided over the oxide semiconductor film of the second transistor is an oxide insulating film and a nitride insulating film. In the case of a laminated structure of an oxide insulating film, the oxide insulating film is difficult to transmit nitrogen. It is preferable that the film has a barrier property that can

[0022] By doing so, nitrogen is prevented from diffusing into the oxide semiconductor film of the second transistor. This can suppress the fluctuation of the electrical characteristics of the second transistor. When an oxide semiconductor film is used for a transistor, the oxide insulating film is difficult to transmit nitrogen. In other words, it is preferable that the film has a barrier property against nitrogen. Fluctuations in the electrical characteristics of the first transistor can be suppressed.

[0023] In addition, one electrode of the capacitor is connected to the source electrode or the drain electrode of the second transistor. The conductive film formed in the process of forming the contact electrode can be used to electrically connect to the capacitance line. In addition, an oxide semiconductor film that functions as one of the electrodes is formed in direct contact with the capacitance line. This allows one electrode to be electrically connected to the capacitance line.

[0024] In the capacitor, the conductive film electrically connecting one electrode and the capacitor line is For example, the oxide semiconductor film may be provided in contact with an end portion of the oxide semiconductor film that functions as an electrode. The oxide film can be provided along the outer periphery of the semiconductor film. The conductivity of the oxide semiconductor film can be increased. By this, the oxide semiconductor film can easily function as one electrode of a capacitor. do.

[0025] In the above, the capacitance line is connected to the scanning line which also functions as the gate electrode of the second transistor. The first transistor may extend in a direction parallel to the first transistor and be provided on the same surface. It extends parallel to the signal line, which also functions as a source electrode or a drain electrode, and is on the same surface as the signal line. It may be provided on the

[0026] In the above, a pixel electrode electrically connected to the second transistor; An organic insulating film may be provided between the insulating film provided on the oxide semiconductor film of the photoconductor. In this way, the pixel electrode and the source electrode or drain electrode of the second transistor are This can reduce the parasitic capacitance with other conductive films such as electrodes, improving the electrical characteristics of the semiconductor device. For example, signal delays in semiconductor devices can be reduced.

[0027] In this case, it is effective to make the thickness of the dielectric film thin in order to increase the capacitance of the capacitive element. Therefore, it is preferable to remove the organic insulating film on the region where the capacitor element is to be formed. Therefore, hydrogen, water, and the like contained in the organic insulating film are transferred to the oxide semiconductor film of the second transistor. In order to prevent diffusion, a region overlapping with the oxide semiconductor film of the second transistor is It is preferable to remove the organic insulating film.

[0028] In the above, the oxide semiconductor film of the second transistor is used as one electrode of the capacitor. When the oxide semiconductor film formed in the forming step is used, the conductivity of the oxide semiconductor film is increased. In other words, in the capacitor element, one electrode is connected to the second transistor. The insulating film is formed on the same surface as the oxide semiconductor film of the capacitor and has higher electrical conductivity than the oxide semiconductor film. It is preferable that the oxide semiconductor film has a thin region. The compound semiconductor film can be made to function sufficiently and easily as one electrode of the capacitance element.

[0029] To increase the electrical conductivity, for example, boron, nitrogen, fluorine, aluminum, phosphorus, One or more elements selected from arsenic, indium, tin, antimony and rare gas elements are added to the oxide. It is preferable that the element be added to the oxide semiconductor film. The oxide semiconductor film is formed on the substrate by an ion implantation method or an ion doping method. The above elements can also be added by exposing the material to plasma containing the above elements. The conductivity of the oxide semiconductor film that functions as one of the electrodes of the cell is 10 S / cm or more and 1000 S / cm or less, preferably 100 S / cm or more and 1000 S / cm or less.

[0030] As described above, in the capacitor, The nitride insulating film of the insulating film provided in the insulating film 1 is in contact with the oxide semiconductor film, The process of adding an element to increase the conductivity, such as by ion doping or ion doping, can be omitted. This allows the yield of semiconductor devices to be improved and the manufacturing cost to be reduced.

[0031] Note that a manufacturing method of a semiconductor device according to one embodiment of the present invention can also be used. Included in. [Effects of the Invention]

[0032] According to one embodiment of the present invention, in a semiconductor device having a driver circuit, it is possible to increase the aperture ratio while reducing the charge It is possible to provide a semiconductor device having a capacitor element with increased capacitance. In the semiconductor device having a high aperture ratio, a capacitor element with a large charge capacity is provided, A semiconductor device with reduced power consumption can be provided. [Brief explanation of the drawings]

[0033] [Figure 1] 1A and 1B are a diagram illustrating a semiconductor device according to one embodiment of the present invention and a circuit diagram of a pixel. [Figure 2] 1A and 1B are a top view and a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 3] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 4] FIG. 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 5] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 6] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 7] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 8] FIG. 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 9] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 10]FIG. 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 11] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 12] FIG. 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 13] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 14] FIG. 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 15] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 16] FIG. 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 17] FIG. 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 18] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 19] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 20] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 21] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 22] 1A and 1B are cross-sectional views illustrating transistors that can be used in a semiconductor device according to one embodiment of the present invention. [Figure 23] 1A and 1B are cross-sectional views illustrating transistors that can be used in a semiconductor device according to one embodiment of the present invention. [Figure 24] 1A and 1B are cross-sectional views illustrating transistors that can be used in a semiconductor device according to one embodiment of the present invention. [Figure 25] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 26] FIG. 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 27] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 28] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 29] FIG. 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 30] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 31] FIG. 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 32] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 33] 1A to 1C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Figure 34] 1A and 1B are cross-sectional views illustrating transistors that can be used in a semiconductor device according to one embodiment of the present invention. [Figure 35] FIG. 1 is a top view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 36] FIG. 1 is a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 37] 1A and 1B are a top view and a cross-sectional view illustrating a semiconductor device according to one embodiment of the present invention. [Figure 38] 1A to 1C illustrate electronic devices using a semiconductor device which is one embodiment of the present invention. [Figure 39] 1A to 1C illustrate electronic devices using a semiconductor device which is one embodiment of the present invention. [Figure 40] FIG. 1 is a diagram illustrating a sample structure. [Figure 41] FIG. 1 is a diagram illustrating sheet resistance. [Figure 42] FIG. 1 is a diagram illustrating the results of SIMS measurements. [Figure 43] FIG. 1 is a diagram illustrating the results of ESR measurements. [Figure 44] FIG. 1 is a diagram illustrating the results of ESR measurements. [Figure 45] FIG. 1 is a diagram illustrating sheet resistance. [Figure 46] FIG. 1 is a diagram illustrating sheet resistance. [Figure 47] A diagram explaining the bulk model of InGaZnO4. [Figure 48] Diagram illustrating the formation energy and thermodynamic transition levels of VoH. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following description, and it is understood by those skilled in the art that various modifications can be made to the modes and details. Furthermore, the present invention should not be construed as being limited to the description of the following embodiments. It is not something that can be done.

[0035] In the configuration of the present invention described below, the same parts or parts having similar functions are designated as the same. The same reference numerals are used in common among different drawings, and repeated explanations thereof will be omitted. When referring to a part that has a function, the hatch pattern is the same and no particular symbol is attached. be.

[0036] In each figure described in this specification, the size of each structure, the thickness of a film, or the area is shown for clarity. The figures may be exaggerated for illustrative purposes only and are not necessarily limited to that scale.

[0037] In this specification and elsewhere, ordinal numbers such as 1st, 2nd, etc. are used for convenience. It does not indicate the order of steps or the order of layers. It does not indicate a specific name for the purpose of identification.

[0038] In addition, the function of the "source" and "drain" in the present invention is to control the flow of current during circuit operation. When the direction changes, the positions may be reversed. The terms "source" and "drain" may be used interchangeably.

[0039] Voltage refers to the potential difference between two points, and potential refers to the electrostatic field at a certain point. This refers to the electrostatic energy (electrical potential energy) of a unit charge in a particle. However, in general, the potential difference between the potential at a certain point and a reference potential (for example, ground potential) This is simply called potential or voltage, and potential and voltage are often used synonymously. Therefore, in this specification, unless otherwise specified, the term "potential" may be read as "voltage." , voltage may be read as potential.

[0040] In this specification, when etching is performed after photolithography, The mask formed by the photolithography process is removed.

[0041] (Embodiment 1) In this embodiment, a semiconductor device according to one embodiment of the present invention will be described with reference to drawings. Note that in this embodiment, a liquid crystal display device is used as an example of a semiconductor device according to one embodiment of the present invention. explain.

[0042] <Configuration of semiconductor device> FIG. 1A shows an example of a semiconductor device. The element part 100, the scanning line driving circuit 104, and the signal line driving circuit 106 are parallel or substantially parallel to each other. m scanning lines 107 arranged in rows and having potentials controlled by a scanning line driving circuit 104 The signal line driving circuit 106 controls the potential of each of the electrodes. The pixel section 100 is arranged in a matrix. The pixel array has a plurality of pixels 101. The pixels 101 are arranged parallel or approximately parallel along the scanning line 107. The capacitance lines 115 are arranged along the signal line 109. They may be arranged in rows or substantially parallel to one another. Furthermore, m and n are both integers of 1 or greater.

[0043] Each scanning line 107 is connected to one of the pixels 101 arranged in m rows and n columns in the pixel section 100. The signal lines 109 are electrically connected to the n pixels 101 arranged in any one of the rows. is m pixels 101 arranged in any one of the columns among the pixels 101 arranged in m rows and n columns. 1. Each capacitance line 115 is electrically connected to the pixel 101 arranged in m rows and n columns. Among them, the n pixels 101 arranged in any one row are electrically connected. 115 are arranged parallel or approximately parallel to each other along the signal line 109, Among the pixels 101 arranged in n columns, m pixels 101 arranged in any one column are electrically connected. It is connected to the target.

[0044] FIG. 1B is an example of a circuit diagram of a pixel 101 included in the semiconductor device shown in FIG. The pixel 101 shown in FIG. 1B is electrically connected to a scanning line 107 and a signal line 109. One electrode of the transistor 103 is electrically connected to a capacitor line 115 that supplies a constant potential. The other electrode of the capacitor 1 is electrically connected to the drain electrode of the transistor 103. 05, and the pixel electrode is the drain electrode of the transistor 103 and the other electrode of the capacitor 105. An electrode (counter electrode) provided opposite the pixel electrode supplies a counter potential. and a liquid crystal element 108 electrically connected to the wiring.

[0045] A semiconductor film having a channel formation region of a transistor is processed under appropriate conditions. The use of an oxide semiconductor film can significantly reduce the off-state current of a transistor. The semiconductor film included in the transistor 103 is an oxide semiconductor film 111.

[0046] The capacitor 105 can be formed by utilizing the same process as that of the transistor 103. One electrode of the capacitor 105 is formed of a light-transmitting semiconductor film, specifically, an oxide semiconductor film. That is, the capacitance element 105 is a MOS (Metal Oxide Semiconductor) It can be considered a semiconductor capacitor.

[0047] The liquid crystal element 108 faces the substrate on which the transistor 103 and the pixel electrode 121 are formed. The optical modulation effect of the liquid crystal sandwiched between the substrate on which the electrode 154 is formed allows the transmission or is an element that controls non-transmission. The optical modulation action of the liquid crystal is controlled by the electric field (horizontal The electric field may be oriented in a diagonal direction, a longitudinal direction, or a diagonal direction.

[0048] The scanning line driver circuit 104 and the signal line driver circuit 106 are composed of a logic circuit section and a switch section or a barrier section. The detailed configuration of the scanning line driving circuit 104 and the signal line driving circuit 106 Although the description is omitted, the scanning line driver circuit 104 and the signal line driver circuit 106 include transistors. It contains data.

[0049] Transistors included in one or both of the scanning line driver circuit 104 and the signal line driver circuit 106 The transistor 103 of the pixel 101 can be formed by utilizing the same process as that for forming the transistor 103. That is, one or both of the scanning line driving circuit 104 and the signal line driving circuit 106 The first transistor 103 and the pixel electrode 121 can be provided on the same substrate. In this way, one or both of the scanning line driver circuit 104 and the signal line driver circuit 106 are mounted on the substrate. By forming a body, the number of parts in the semiconductor device can be reduced, thereby reducing manufacturing costs. It is possible.

[0050] In order to increase the speed at which the pixels 101 are scanned, the operation of the scanning line driving circuit 104 It is necessary to increase the speed, and specifically, the transistors included in the scanning line driving circuit 104 Increase in the operating speed of the transistor, and increase in the drain current (on-current) that flows when the transistor is conducting and an increase in the field-effect mobility of the transistor. The transistors included in the scanning line driving circuit 104 are dual gate transistors. The dual gate transistor has gates above and below the semiconductor film that overlap the semiconductor film. The presence of the electrodes can increase the operating speed of the transistor. In addition, since an electric field is applied from above and below the semiconductor film, a sufficient channel can be formed, and the transistor The on-state current and field effect mobility of the transistor can be increased. The transistor included in the circuit 106 can also be a dual gate transistor. Cut.

[0051] Next, in the semiconductor device according to one embodiment of the present invention, a capacitance line provided in the pixel portion 100 and a back gate electrode of a dual gate transistor included in the scanning line driving circuit 104. The laminated structure with the wiring including the wiring will be explained. Figure 2 shows a diagram explaining the laminated structure. 2(A) is a top view of a part of the semiconductor device, and FIG. 2(B) is a diagram showing the structure of the semiconductor device along the dashed line X1-X in FIG. 2(A). 2 and a cross section taken along dashed dotted line Y1-Y2.

[0052] FIG. 2A shows a pixel section 100, a capacitance line 115, a scanning line driving circuit 104, and a scanning line The back gate electrode of the dual gate transistor 15 included in the drive circuit 104 For clarity of the drawing, the capacitance line 92 is shown in the pixel section 100. Components other than 115 (pixels, signal lines, transistors, capacitors, liquid crystal elements, etc.) are not included. In addition, in the scanning line driving circuit 104, in order to clarify the drawing, The components are omitted.

[0053] As shown in FIG. 2A, the semiconductor device of one embodiment of the present invention includes a capacitor line 115 and a wiring 9 2 are electrically connected through the opening 94. That is, the capacitance line 115 and the wiring 92 are The back gate electrode of the dual gate transistor 15 and the capacitor The oxide semiconductor that functions as one electrode of the capacitor element 105 electrically connected to the capacitance line 115 The conductive film 119 has the same potential (see FIG. 1(B)).

[0054] FIG. 2B illustrates the structure of the dual gate transistor 15 and the opening 94. The dual gate transistor 15 is fabricated using the same process as the transistor 103. It can be formed.

[0055] As shown in FIG. 2B, the semiconductor device according to one embodiment of the present invention has a cross section taken along the line X1-X2. A gate electrode 17a is provided on the substrate 102, and a gate electrode 17a is provided on the gate electrode 17a. An insulating film 12 is provided, and a gate insulating film 12 is provided on a region overlapping with the gate electrode 17a. An oxide semiconductor film 11 is provided, and a source electrode 19a and a The gate insulating film 12, the source electrode 19a, and the drain electrode 13a are provided. An insulating film 29, an insulating film 31, and an insulating film 32 are provided on the semiconductor film 11 and the drain electrode 13a. A back gate electrode is formed on the region of the insulating film 32 that overlaps with the oxide semiconductor film 11. Wiring 92 including the wiring is provided.

[0056] In addition, in the semiconductor device according to one aspect of the present invention, a semiconductor device is provided on the substrate 102 in the cross section Y1-Y2. A capacitance line 115 is provided on the same surface as the gate electrode 17a. A conductive film 16, an insulating film 29, an insulating film 31, and an insulating film 32 are provided on the gate electrode 5. An opening is formed in the insulating film 12, the insulating film 29, the insulating film 31, and the insulating film 32, and reaches the conductive film 16. An opening 94 is provided, and a wiring 92 is provided in the opening 94. 5 and the wiring 92 are electrically connected by a conductive film 16. The conductive film 16 is It can be formed by utilizing the process for forming the electrode 19a and the drain electrode 13a.

[0057] The capacitance line 115 and the wiring 92 are electrically connected to each other by the conductive material as described above. In addition to the structure in which the conductive film 16 is electrically connected, the capacitor line 115 and the wiring may be connected without providing the conductive film 16. 92 can be configured to be in direct contact with each other.

[0058] The substrate 102, the gate electrode 17a, the capacitance line 115, and the gate insulating film 12 An underlying insulating film may be provided between them.

[0059] In this case, the capacitance line 115 and the dual gate transistor included in the scanning line driving circuit 104 are The structure in which the wiring 92 including the back gate electrode of the transistor 15 is electrically connected will be described. However, the semiconductor device according to one embodiment of the present invention is not limited to this structure. Wiring including the back gate electrode of the dual gate transistor included in the line driving circuit 106 The power supply voltage Vcc can be electrically connected to the power supply voltage Vcc.

[0060] As described above, the semiconductor device according to one embodiment of the present invention has the capacitor line 115 and the dual gate transistor. The capacitor 15 is electrically connected to the wiring 92 including the back gate electrode of the capacitor 15. By controlling the potential of the line 115, the potential of the back gate electrode can be controlled. That is, according to one embodiment of the present invention, it is possible to omit a structure for controlling the potential of the back gate electrode. The transistors included in the scanning line driving circuit 104 are dual gate transistors. 15, the operating speed of the drive circuit can be increased. It is possible to obtain a semiconductor device that can achieve both increased speed and reduced power consumption. Since the configuration for controlling the potential of the back gate electrode can be omitted, the number of components of the semiconductor device can be reduced. Therefore, the manufacturing cost of the semiconductor device according to one embodiment of the present invention can be reduced. do.

[0061] Next, a specific configuration example of the pixel 101 included in the semiconductor device of one embodiment of the present invention will be described. A top view of the pixel 101 is shown in FIG. 3. For clarity of the drawing, FIG. 3 is Some of the components of the semiconductor device (such as the liquid crystal element 108) are omitted.

[0062] In FIG. 3, the scanning lines 107 extend in a direction (horizontal direction in the drawing) substantially perpendicular to the signal lines 109. The signal lines 109 extend in a direction substantially perpendicular to the scanning lines 107 (the vertical direction in the drawing). The capacitance line 115 is provided so as to extend in a direction parallel to the scanning line 107. The scanning lines 107 and the capacitance lines 115 are included in the scanning line driving circuit 104. Wiring 92 including the back gate electrode of the dual gate transistor 15 (see FIG. 2(A)) The signal line 109 is electrically connected to the signal line driver circuit 106 (see FIG. 1A). and is electrically connected.

[0063] The transistor 103 is provided in the area where the scanning line 107 and the signal line 109 intersect. The transistor 103 includes at least an oxide semiconductor film 11 having a channel formation region. 1, a gate electrode, a gate insulating film (not shown in FIG. 3), a source electrode, and a drain electrode. and an electrode.

[0064] Since the transistor 103 includes the oxide semiconductor film 111, the off-state current of the transistor This can significantly reduce the current, thereby reducing the power consumption of the semiconductor device.

[0065] The scanning line 107 includes a region that functions as a gate electrode of the transistor 103, and The line 109 includes a region that functions as the source electrode of the transistor 103. includes a region that functions as the drain electrode of transistor 103, and is connected through opening 117 It is electrically connected to the pixel electrode 121. In FIG. 3, the pixel electrode 121 is The illustration omits the linking.

[0066] The region functioning as a gate electrode is formed by at least the oxide semiconductor film 1 The area that functions as a source electrode is a small area in the signal line 109. The region that functions as a drain electrode is a region that overlaps with at least the oxide semiconductor film 111. indicates a region of the conductive film 113 that overlaps with at least the oxide semiconductor film 111. In the following, the gate electrode of the transistor 103 is referred to as a gate electrode 107a. The source electrode of the transistor 103 is referred to as a source electrode 109a. The in-electrode of the transistor 103 may be referred to as the drain electrode 113a. The gate electrode is also referred to as the scanning line 107, and the source electrode of the transistor 103 is also referred to as the scanning line 107. , may be referred to as signal line 109.

[0067] The capacitance element 105 is provided in a region surrounded by the capacitance line 115 and the signal line 109 in the pixel 101. The capacitor element 105 is connected to a capacitor line through a conductive film 125 provided in the opening 123. The capacitor 105 is electrically connected to the light-transmitting oxide semiconductor film 115. 19, a pixel electrode 121 having light-transmitting properties, and a dielectric film included in the transistor 103. The capacitor element 10 is made up of a transparent insulating film (not shown in FIG. 3). 5 has translucency.

[0068] Since the capacitor 105 has a light-transmitting property, the capacitor 105 is large ( Therefore, it is possible to form a semiconductor device with an increased aperture ratio and an increased charge capacity. Furthermore, by improving the aperture ratio, a semiconductor device with excellent display quality can be obtained. A conductor device can be obtained.

[0069] The capacitance of the capacitor 105 varies depending on the area where the pair of electrodes overlap. If the pixel size is reduced to increase the resolution, the size of the capacitance element will also increase. As a result, the liquid crystal element can be operated satisfactorily. Since the capacitor 105 has a light-transmitting property, the liquid crystal element 108 The capacitance element 105 can be formed over the entire operating range of the pixel. The capacitor element 105 can be formed (in a large area). As long as the charge capacity can be secured, the pixel density and resolution can be increased. can.

[0070] Therefore, one aspect of the present invention is to provide a display having a pixel density of 200 ppi or more, or even 300 ppi or more. The present invention can be suitably used for a high-resolution display device. Even in display devices with a large aperture ratio, the aperture ratio can be improved, so that the The light from the light source can be used efficiently, and the power consumption of the display device can be reduced. .

[0071] Here, the characteristics of a transistor using an oxide semiconductor will be described. The transistor used is an n-channel transistor. Oxygen vacancies can generate carriers, which can degrade the electrical characteristics and reliability of transistors. For example, the threshold voltage of a transistor may be shifted in the negative direction, causing the gate When the gate voltage is 0V, the drain current may flow. The fact that drain current flows when the gate voltage is 0V is called a normally-on characteristic. A transistor that can be considered as having no drain current when the drain voltage is 0V. This is called a normally-off characteristic.

[0072] Therefore, when an oxide semiconductor film is used, defects contained in the oxide semiconductor film, typically oxygen It is preferable to reduce defects as much as possible. For example, the direction of the magnetic field is parallel to the film surface. The spin density (contained in the oxide semiconductor film) of g value = 1.93 by electron spin resonance applied to the It is preferable that the defect density is reduced to below the detection limit of the measuring instrument. It is desirable to reduce defects, typically oxygen vacancies, contained in the oxide semiconductor film as much as possible. This can prevent the transistor from becoming normally on, and the power consumption of the semiconductor device can be improved. The thermal characteristics and reliability can be improved.

[0073] The negative shift in the threshold voltage of a transistor is not only due to oxygen vacancies, but also to oxide It can also be caused by hydrogen (including hydrogen compounds such as water) contained in the semiconductor film. The hydrogen contained in the oxide semiconductor film reacts with oxygen that bonds to metal atoms to form water. In both cases, a defect (which can also be called an oxygen defect) is created in the lattice where oxygen has been desorbed (or the part where oxygen has been desorbed). In addition, some of the hydrogen reacts with oxygen to generate electrons, which act as carriers. Therefore, a transistor including an oxide semiconductor film containing hydrogen is a normally-on transistor. This is likely to result in poor performance.

[0074] Therefore, hydrogen in the oxide semiconductor film 111 of the transistor 103 is reduced as much as possible. Specifically, it is preferable that the oxide semiconductor film 111 be (SIMS: Secondary Ion Mass Spectrometry) The resulting hydrogen concentration is 5 x 10 18 atoms / cm 3 Less than 1 x 10 18 atoms / cm 3 Less than or equal to 5 × 10 17 atoms / cm 3 Further details are as follows: Preferably 1 x 10 16 atoms / cm 3 The following applies.

[0075] The oxide semiconductor film 111 is formed by adding an alkali metal or is the concentration of alkaline earth metals, 1×10 18 atoms / cm 3 Below, preferably 2 x 1 0 16 atoms / cm 3 Alkali metals and alkaline earth metals are oxide semiconductors. When coupled to a conductor, carriers may be generated, increasing the off-state current of the transistor 103. This can sometimes be done.

[0076] In addition, when nitrogen is contained in the oxide semiconductor film, electrons that serve as carriers are generated, and the carriers The density increases and the oxide semiconductor film containing nitrogen is easily converted to n-type. The transistor tends to be normally on. Therefore, it is preferable that the nitrogen concentration is reduced as much as possible. For example, the nitrogen concentration is 5×10 1 8 atoms / cm 3 It is preferable to do the following:

[0077] Furthermore, when an oxide semiconductor film contains a Group 14 element such as silicon or carbon, the carrier The electrons generated by the oxide semiconductor film are n-type, which increases the carrier density. In the transistor 103 having the gate insulating film 127 (not shown in FIG. 3), The oxide semiconductor film 111 is then subjected to secondary ion mass spectrometry. The silicon concentration is 3 x 10 18 atoms / cm 3 Less than or equal to 3 x 10 17 ato ms / cm 3 The following is the result of the secondary ion mass spectrometry at the interface. The carbon concentration is 3×1018 atoms / cm 3 Less than or equal to 3 x 10 17 atom s / cm 3 The following applies.

[0078] From the above, impurities (hydrogen, nitrogen, silicon, carbon, alkali metals or alkaline earth metals) By using the oxide semiconductor film 111 that is highly purified by reducing the amount of oxides such as fluorine and fluorine atoms as much as possible, The transistor 103 can be prevented from becoming a normally-on transistor. Therefore, a semiconductor device having good electrical characteristics can be fabricated. In addition, a semiconductor device with improved reliability can be manufactured.

[0079] The reason why the off-state current of a transistor using a highly purified oxide semiconductor film is low is that This can be proven through various experiments. For example, if the channel width W is 1×10 6 Channel length in μm Even with an element with L of 10 μm, the voltage between the source electrode and the drain electrode (drain voltage) In the range of 1V to 10V, the off-state current is below the measurement limit of the semiconductor parameter analyzer. Bottom, i.e. 1 x 10 -13 In this case, the transistor The off-state current, which is equivalent to the value divided by the channel width of the transistor, must be 100 A / μm or less. In addition, by connecting a capacitor and a transistor, the current flowing into or out of the capacitor can be The off-state current was measured using a circuit in which charge flowing out of the transistor was controlled by the transistor. In this measurement, a highly purified oxide semiconductor film was used as a channel formation region of the transistor. The off-state current of the transistor is measured from the change in the amount of charge per unit time of the capacitor. As a result, when the voltage between the source and drain electrodes of the transistor is 3V, several It was found that an even lower off-state current of 10 yA / μm could be obtained. A transistor including such an oxide semiconductor film has an extremely small off-state current.

[0080] Next, cross-sectional views taken along dashed lines A1-A2 and B1-B2 in FIG. 3 are shown in FIG. 4 shows a configuration including a liquid crystal element 108.

[0081] The cross-sectional structure of the pixel 101 is as follows: A scanning line 107 including the scanning line 107 and a capacitance line 115 provided on the same surface as the scanning line 107 are provided. A gate insulating film 127 is provided on the scanning line 107 and the capacitance line 115. The oxide semiconductor film 111 is provided over a region of the insulating film 127 that overlaps with the scan line 107. The oxide semiconductor film 119 is provided over the gate insulating film 127. 1 and a gate insulating film 127, a signal line 109 including a source electrode 109a, and a drain electrode 109b are provided on the gate insulating film 127. A conductive film 113 functioning as an electrode 113a is provided. An opening 123 is provided that reaches the capacitor line 115, and the conductive film 125 is The gate insulating film 127 is provided in contact with the oxide semiconductor film 119 and in the opening 123. , over the signal line 109, over the oxide semiconductor film 111, over the conductive film 113, over the conductive film 125, and over the oxide semiconductor film 112. an insulating film 129 which functions as a protective insulating film for the transistor 103 over the nitride semiconductor film 119; The insulating film 129, the insulating film 131, and the insulating film 132 are provided. The insulating film 132 is provided with an opening 117 that reaches the conductive film 113. The substrate 102, the scanning lines 107, the capacitance lines 115, and the like are provided with a pixel electrode 121. A base insulating film may be provided between the gate insulating film 127 and the insulating film 128.

[0082] The pixel 101 also has a liquid crystal element 108. The cross-sectional structure of the liquid crystal element 108 is as follows: The surface of the substrate 150 facing the substrate 102 overlaps with at least the transistor 103. A light-shielding film 152 is provided in the overlapping area, and a light-transmitting film is provided to cover the light-shielding film 152. A counter electrode 154, which is a conductive film, is provided and covers the light-shielding film 152 and the counter electrode 154. The alignment film 156 is provided on the pixel electrode 121 and the insulating film 132. A liquid crystal 160 is sandwiched between the substrate 102 and the substrate 150. The liquid crystal 160 is formed by an alignment film 156 provided on the substrate 150 side and an alignment film 157 provided on the substrate 102 side. It is in contact with the alignment film 158 .

[0083] Note that when the semiconductor device according to one embodiment of the present invention is used as a liquid crystal display device, the light source device, and optical members such as polarizing plates provided on the substrate 102 side and the substrate 150 side, respectively. (Optical substrate), a seal material for fixing the substrate 102 and the substrate 150 is required, but this These will be discussed later.

[0084] In the capacitor 105 described in this embodiment, one of a pair of electrodes is made of an oxide semiconductor. The other electrode of the pair of electrodes is a pixel electrode 121. The dielectric films provided therebetween are the insulating film 129, the insulating film 131, and the insulating film 132.

[0085] Here, the operating principle of the capacitive element 105 will be described.

[0086] The oxide semiconductor film 119 has the same structure as the oxide semiconductor film 111. This functions as one electrode of the pixel electrode 121 as the gate electrode and the insulating film 129 The insulating film 131 and the insulating film 132 are used as a gate insulating film, and the capacitance line 115 is used as a source electrode or a drain electrode. As a result, the capacitor element 105 can be regarded as a transistor. This is because the capacitance can be increased to make the oxide semiconductor film 119 conductive. The element 105 can be a MOS capacitor, and the potential applied to the capacitance line 115 can be By controlling the temperature, the oxide semiconductor film 119 is brought into a conductive state, and the oxide semiconductor film 119 is turned into a capacitive element. In this case, the potential applied to the capacitance line 115 can be The potential of the pixel electrode 121 is set as follows: The capacitance element 105 (MOS capacitor) is always conductive. In order to keep the state, the potential of the capacitance line 115 is always set to the potential applied to the pixel electrode 121. It is necessary to set the value lower than the threshold voltage of the capacitance element 105 (MOS capacitor). That is, since the oxide semiconductor film 119 and the oxide semiconductor film 111 have the same structure, The potential of the capacitor line 115 should be set lower by the threshold voltage of the transistor 103 or more. In this way, a channel is formed in the oxide semiconductor film 119, and therefore, the capacitor 30 5 (MOS capacitor) can be kept in a constant conductive state.

[0087] The components of the above structure are described in detail below.

[0088] There is no particular restriction on the material of the substrate 102, but at least in the manufacturing process of the semiconductor device, For example, a glass substrate, There are ceramic substrates, plastic substrates, etc., and for glass substrates, barium borosilicate Non-alkali glass such as acid glass, aluminoborosilicate glass or aluminosilicate glass It is also possible to use a non-transparent substrate such as a stainless steel alloy. In this case, it is preferable to provide an insulating film on the surface of the substrate. 2. Quartz substrate, sapphire substrate, single crystal semiconductor substrate, polycrystalline semiconductor substrate, compound semiconductor substrate It is also possible to use a solid substrate, SOI (Silicon On Insulator) substrate, etc. can.

[0089] The scanning lines 107 and the capacitance lines 115 are preferably made of a metal film because they carry a large current. Typically, molybdenum (Mo), titanium (Ti), tungsten (W) and tantalum are used. (Ta), aluminum (Al), copper (Cu), chromium (Cr), neodymium (Nd), A single-layer structure using metal materials such as candium (Sc) or alloy materials containing these as the main components. It is provided in a laminated or laminated structure.

[0090] As an example of the scanning lines 107 and the capacitance lines 115, aluminum containing silicon is used. Single layer structure, double layer structure with titanium laminated on aluminum, titanium laminated on titanium nitride Two-layer structure with tungsten on titanium nitride, two-layer structure with tungsten on tantalum nitride Two-layer structure with stainless steel laminated, two-layer structure with copper laminated on copper-magnesium-aluminum alloy Structure, three-layer structure in which copper is layered on titanium nitride and tungsten is formed on top of that There is.

[0091] Furthermore, the scanning lines 107 and the capacitance lines 115 are made of a transparent material that can be applied to the pixel electrodes 121. A conductive material having a high conductivity can be used. In the case of a reflective display device, the pixel electrode 121 is made of a conductive material (e.g., In this case, the substrate 102 may be a substrate that does not have light-transmitting properties. It can be used.

[0092] Furthermore, as the material of the scanning line 107 and the capacitance line 115, a metal oxide containing nitrogen, specifically The oxides include In-Ga-Zn oxides containing nitrogen, In-Sn oxides containing nitrogen, and In-Ga oxides containing nitrogen, In-Zn oxides containing nitrogen, and Sn oxides containing nitrogen Materials such as In-based oxides containing nitrogen and metal nitride films (InN, SnN, etc.) can be used. These materials have a work function of 5 eV (electron volts) or more. By using a metal oxide as the scanning line 107 (gate electrode 107a), the transistor 1 The threshold voltage of O3 can be changed in the positive direction, and so-called normally-off characteristics can be achieved. For example, a transistor using an In-Ga-Zn oxide containing nitrogen can be realized. In this case, the nitrogen concentration is at least higher than that of the oxide semiconductor film 111, specifically, the nitrogen concentration is 7 atomic percent. % or more of an In-Ga-Zn-based oxide can be used.

[0093] The scanning lines 107 and the capacitance lines 115 are made of low-resistance materials such as aluminum and copper. It is preferable to use aluminum or copper to reduce signal delay and improve display quality. Aluminum has low heat resistance and may develop hillocks, whiskers, or Defects due to migration are likely to occur. To prevent aluminum migration, Therefore, aluminum is often melted by other metals such as molybdenum, titanium, and tungsten. It is preferable to use a metal material with a high migration resistance. To prevent defects caused by ions and the diffusion of copper elements, copper is mixed with molybdenum, titanium, tungsten, etc. It is preferable to laminate a metal material having a melting point higher than that of copper.

[0094] 3 and 4, the scanning line 107 (gate electrode 107a) is made of an oxide. The semiconductor film 111 can be provided in the region of the scanning line 107 (gate electrode 107a). As shown in FIG. 3, the oxide semiconductor film 111 is preferably formed in a shape similar to that of the scan line 107. In this way, the scanning line of the substrate 102 is The light (liquid crystal display) irradiated from the opposite surface (the back surface of the substrate 102) to the surface on which the 107 is provided is In a display device, the scanning line 107 blocks light from a light source device such as a backlight. The electrical characteristics (for example, threshold voltage) of the transistor 103 are prevented from fluctuating or decreasing. This can be done.

[0095] The gate insulating film 127 is made of, for example, silicon oxide, silicon oxynitride, silicon nitride oxide, Silicon nitride, aluminum oxide, hafnium oxide, gallium oxide or Ga-Zn metal The oxide semiconductor film has a single layer structure or a stacked layer structure using an insulating material such as an oxide. In order to improve the interface characteristics with 111, at least an oxide semiconductor is formed in the gate insulating film 127. The region in contact with the conductor film 111 is preferably formed of an oxide insulating film.

[0096] In addition, the gate insulating film 127 is formed of an insulating film having a barrier property against oxygen, hydrogen, water, etc. By providing the insulating layer, oxygen contained in the oxide semiconductor film 111 can be diffused to the outside, and oxide can be transferred from the outside. It is possible to prevent hydrogen, water, and the like from entering the semiconductor film 111. Examples of insulating films having a barrier property include an aluminum oxide film, an aluminum oxynitride film, and an oxide film. gallium oxide film, gallium oxynitride film, yttrium oxide film, yttrium oxynitride film, oxide Examples of the film include hafnium nitride film, hafnium oxynitride film, and silicon nitride film.

[0097] The gate insulating film 127 is made of hafnium silicate (HfSiO x ), nitrogen-containing Hafnium silicate (HfSi x O y N z ), hafnium aluminate with nitrogen HfAl x O y N z ), high-k materials such as hafnium oxide and yttrium oxide By using this, the gate leakage of the transistor 103 can be reduced.

[0098] The gate insulating film 127 preferably has the following stacked structure: A silicon nitride film with a small amount of defects is provided as a contact film, and a second silicon nitride film is formed on the first silicon nitride film. As the silicon nitride film, a silicon nitride film with a small amount of hydrogen desorption and ammonia desorption is provided. On the second silicon nitride film, any of the oxide insulating films listed in the gate insulating film 127 is formed. It is preferable to provide

[0099] The second silicon nitride film is a film that has a hydrogen molecule desorption rate of 500 ppm or more in thermal desorption gas spectroscopy. x10 21 molecule / cm 3 Less than 3 x 10 21 molecule / cm 3 The following are more preferred: 1×10 21 molecule / cm 3 The number of ammonia molecules released is 1 × 10 22 molecule / cm 3 Less than 5 x 10 21 molecule / cm 3 or less, more preferably 1 × 10 2 1 molecule / cm 3 It is preferable to use a nitride insulating film having the following properties: The gate insulating film 127 is formed by using the silicon nitride film and the second silicon nitride film as a part of the gate insulating film 127. The insulating film 127 is a gate insulating film having a small amount of defects and a small amount of hydrogen and ammonia desorbed. As a result, the hydrogen and nitrogen contained in the gate insulating film 127 can be This allows the amount of oxygen transferred to the oxide semiconductor film 111 to be reduced.

[0100] In a transistor using an oxide semiconductor, the interface between the oxide semiconductor film and the gate insulating film Alternatively, if a trap state (also called an interface state) exists in the gate insulating film, the threshold of the transistor The shift in the threshold voltage, typically in the negative direction, and the The sub-threshold voltage required to change the drain current by one order of magnitude when the device is turned on. This causes an increase in the shock coefficient (S value). As a result, the electrical characteristics of each transistor For this reason, silicon nitride with a low defect content is used as the gate insulating film. By using an oxide insulating film, an oxide semiconductor film can be formed in a region in contact with the oxide semiconductor film 111. This reduces the negative shift of the threshold voltage and suppresses the increase in the S value. Cut.

[0101] The thickness of the gate insulating film 127 is 5 nm or more and 400 nm or less, and more preferably 10 nm or more. The thickness is preferably at most 300 nm, more preferably at least 50 nm and at most 250 nm.

[0102] The oxide semiconductor film 111 can have an amorphous structure, a single-crystal structure, or a polycrystalline structure. The thickness of the oxide semiconductor film 111 is greater than or equal to 1 nm and less than or equal to 100 nm, preferably greater than or equal to 1 nm. more preferably 1 nm or more and 50 nm or less, and even more preferably 3 nm or less The upper limit is 20 nm or less.

[0103] As oxide semiconductors applicable to the oxide semiconductor film 111, an energy gap of 2 eV It is preferably 2.5 eV or more, more preferably 3 eV or more. By using an oxide semiconductor with a wide energy gap, the off-state current of the transistor 103 can be reduced. It can be reduced.

[0104] The oxide semiconductor applicable to the oxide semiconductor film 111 is at least indium (In) or It is preferable that the alloy contains zinc (Zn), or it is preferable that the alloy contains both In and Zn. In addition, in order to reduce variations in the electrical characteristics of transistors using the oxide semiconductor, It is preferable to have one or more stabilizers together with them.

[0105] The stabilizers include gallium (Ga), tin (Sn), hafnium (Hf), and aluminum. Aluminum (Al) or zirconium (Zr) are also used. The lanthanides are lanthanum (La), cerium (Ce), and praseodymium (P r), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium ( Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium Er, Thulium, Ytterbium, Lutetium, etc. do.

[0106] Examples of oxide semiconductors that can be used for the oxide semiconductor film 111 include indium oxide, Tin oxide, zinc oxide, In-Zn oxide, which is an oxide containing two types of metals, Sn-Zn based oxides, Al-Zn based oxides, Zn-Mg based oxides, Sn-Mg based oxides, In-Mg In-Ga-Zn oxide, which is an oxide containing three metals, oxide (also written as IGZO), In-Al-Zn oxide, In-Sn-Zn oxide Sn-Ga-Zn oxides, Al-Ga-Zn oxides, Sn-Al-Zn oxides , In-Hf-Zn oxide, In-Zr-Zn oxide, In-Ti-Zn oxide, In-Sc-Zn oxide, In-Y-Zn oxide, In-La-Zn oxide, In -Ce-Zn oxide, In-Pr-Zn oxide, In-Nd-Zn oxide, In- Sm-Zn oxide, In-Eu-Zn oxide, In-Gd-Zn oxide, In-T b-Zn oxide, In-Dy-Zn oxide, In-Ho-Zn oxide, In-Er -Zn-based oxides, In-Tm-Zn-based oxides, In-Yb-Zn-based oxides, In-Lu- Zn-based oxides, In-Sn-Ga-Zn-based oxides, which are oxides containing four metals, In -Hf-Ga-Zn oxide, In-Al-Ga-Zn oxide, In-Sn-Al-Z n-based oxides, In-Sn-Hf-Zn-based oxides, and In-Hf-Al-Zn-based oxides It is possible.

[0107] Here, the In-Ga-Zn oxide is an oxide having In, Ga, and Zn as its main components. The ratio of In, Ga, and Zn does not matter. The metal elements may be included.

[0108] In addition, as an oxide semiconductor, InMO3(ZnO) m Using materials expressed as (m>0) M may be one or more metal elements selected from Ga, Fe, Mn, and Co. or the above-mentioned stabilizer element.

[0109] For example, In:Ga:Zn=1:1:1 (=1 / 3:1 / 3:1 / 3), In:Ga: Zn=2:2:1 (=2 / 5:2 / 5:1 / 5), or In:Ga:Zn=3:1: The In-Ga-Zn metal oxide with an atomic ratio of 2 (= 1 / 2: 1 / 6: 1 / 3) was used. Alternatively, In:Sn:Zn=1:1:1 (=1 / 3:1 / 3:1 / 3), In:Sn:Zn=2:1:3 (=1 / 3:1 / 6:1 / 2) or In:Sn:Zn In-Sn-Zn metal oxide with an atomic ratio of 2:1:5 (1 / 4:1 / 8:5 / 8) The atomic ratio of the metal oxide may be calculated by adding the plasma of the atomic ratio above as an error. Includes a 20% fluctuation.

[0110] However, the semiconductor properties and electrical properties required (field effect mobility, etc.) are not limited to these. The appropriate atomic ratio can be used depending on the required semiconductor characteristics (threshold voltage, etc.). To obtain the physical properties, the carrier density, impurity concentration, defect density, atomic ratio of metal elements to oxygen, It is preferable to make the interatomic distance, density, etc. appropriate. For example, In-Sn-Zn system High field-effect mobility can be obtained relatively easily with metal oxides. -Zn-based metal oxides can also have improved field-effect mobility by reducing the defect density in the bulk. It can be done.

[0111] The oxide semiconductor film 119 is formed using an oxide semiconductor that can be used for the oxide semiconductor film 111. The oxide semiconductor film 111 and the oxide semiconductor film 119 can be formed. Therefore, the oxide semiconductor film 119 can be formed by the oxide semiconductor contained in the oxide semiconductor film 111. Contains the metal elements of the conductor.

[0112] The signal line 109, the conductive film 113, the oxide semiconductor film 119 of the capacitor 105, and the capacitor line 1 The conductive film 125 electrically connecting the scanning line 107 and the capacitance line 115 can be applied to the scanning line 107 and the capacitance line 115. The insulating film is provided in a single layer structure or a laminated structure using the material.

[0113] An insulating film that functions as a protective insulating film of the transistor 103 and a dielectric film of the capacitor 105 The film 129, the insulating film 131, and the insulating film 132 are made of materials that can be used for the gate insulating film 127. In particular, the insulating films 129 and 131 are oxide insulating films, and the insulating films It is preferable that the insulating film 132 is a nitride insulating film. Therefore, impurities such as hydrogen and water are introduced from the outside into the transistor 103 (particularly, the oxide semiconductor film 111). The insulating film 129 may not be provided.

[0114] In addition, one or both of the insulating films 129 and 131 may contain oxygen having a stoichiometric composition. It is preferable that the oxide insulating film contains more oxygen than the oxide insulating film. The oxygen elimination from the semiconductor film 111 is prevented, and the oxygen contained in the oxygen-excess region is prevented. The oxygen vacancies can be filled by transferring the oxygen atoms to the oxide semiconductor film 111. For example, The amount of released oxygen molecules measured by thermal desorption spectroscopy (hereinafter referred to as TDS analysis) , 1.0×10 18 molecule / cm 3 By using the above oxide insulating film, oxide semiconductor film 1 The insulating film 129 and the insulating film 131 can compensate for oxygen vacancies in the insulating film 131. In one or both of the above, a region containing oxygen in excess of the stoichiometric composition (oxygen excess region) The oxide insulating film may be an oxide insulating film in which at least the oxide semiconductor film 111 and the The presence of an oxygen-excess region in the overlapping region allows oxygen to be released from the oxide semiconductor film 111. and at the same time, the oxygen contained in the oxygen-excess region is moved to the oxide semiconductor film 111. This makes it possible to compensate for oxygen deficiency.

[0115] The insulating film 131 is an oxide insulating film containing more oxygen than the oxygen required for the stoichiometric composition. In this case, the insulating film 129 is preferably an oxide insulating film that transmits oxygen. In the insulating film 129, all oxygen that enters the insulating film 129 from the outside passes through the insulating film 129 and migrates. Some oxygen does not move and remains in the insulating film 129. Therefore, the insulating film 129 is formed to prevent the diffusion of oxygen. An insulating oxide film with a large coefficient is preferred.

[0116] In addition, the insulating film 129 is in contact with the oxide semiconductor film 111 and therefore only allows oxygen to pass through. It is preferable that the insulating film be an oxide insulating film having a low interface state with the oxide semiconductor film 111. For example, the insulating film 129 is an oxide insulating film having a lower defect density than the insulating film 131. Specifically, the g value measured by electron spin resonance is preferably 2.001(E'-ce The spin density of the nter is 3.0 × 10 17 spins / cm 3 Below 5.0, preferably x10 16 spins / cm 3 The oxide insulating film is shown below. The spin density of g=2.001 is due to the presence of dangling bonds in the insulating film 129. corresponds to the quantity.

[0117] The thickness of the insulating film 129 is 5 nm or more and 150 nm or less, preferably 5 nm or more and 50 nm or less. The thickness of the insulating film 131 can be set to 10 nm or more and preferably 30 nm or less. The thickness can be 30 nm or more and 500 nm or less, preferably 150 nm or more and 400 nm or less. Cut.

[0118] In addition, the insulating film 129 provided over the oxide semiconductor film 111 is The insulating film 131 is an oxide insulating film having a low interface state with the oxide semiconductor film 111. An oxide insulating film containing an excess region or an oxide containing more oxygen than the oxygen that satisfies the stoichiometric composition By using the insulating film, oxygen can be easily supplied to the oxide semiconductor film 111. The desorption of oxygen from the semiconductor film 111 is prevented, and the oxygen contained in the insulating film 131 is oxidized. and oxygen vacancies in the oxide semiconductor film 111 are compensated for. As a result, the transistor 103 is prevented from becoming a normally-on transistor. At the same time, the capacitance element 105 (MOS capacitor) is always in a conductive state. As described above, since the potential applied to the capacitor line 115 can be controlled, the electrical The characteristics and reliability can be improved.

[0119] Note that one or both of the insulating film 129 and the insulating film 131 may be formed using silicon oxynitride or silicon oxynitride. When using an oxide insulating film containing nitrogen, such as silicon dioxide, the nitrogen concentration obtained by SIMS is SIMS detection limit above 3 x 10 20 atoms / cm 3 Less than 1 x 10 18 a toms / cm 3 More than 1×10 20 atoms / cm 3 It is preferable to set the following: By doing so, nitrogen is transferred to the oxide semiconductor film 111 included in the transistor 103. In addition, by doing so, the amount of the oxide insulating film containing nitrogen can be reduced. The amount of defects can be reduced.

[0120] When the insulating film 132 is a nitride insulating film, one or both of the insulating film 129 and the insulating film 131 It is preferable that the insulating film has a barrier property against nitrogen. For example, a dense oxide insulating film By forming a film, it is possible to provide a barrier against nitrogen. Specifically, at 25°C, Oxide insulation with an etching rate of 10 nm / min or less when using 0.5 wt% hydrofluoric acid It is preferably a film.

[0121] The insulating film 132 can be a nitride insulating film with a low hydrogen content. For example, the insulating film is one in which the amount of released hydrogen molecules measured by TDS analysis is 5.0× 10 21 atoms / cm 3 less than 3.0 x 10 21 atoms / cm 3 and more preferably less than 1.0 × 10 21 atoms / cm 3 Nitrided insulation It is the velum.

[0122] The insulating film 132 has a thickness that can suppress the intrusion of impurities such as hydrogen and water from the outside. For example, it is 50 nm or more and 200 nm or less, preferably 50 nm or more and 150 nm or less. The thickness can be set to 50 nm or less and more preferably 100 nm or less.

[0123] In addition, by using a nitride insulating film as the insulating film 132 provided over the insulating film 131, Impurities such as hydrogen and water from the outside penetrate the oxide semiconductor film 111 and the oxide semiconductor film 119. Furthermore, the insulating film 132 may be made of a nitride insulating film having a low hydrogen content. By providing the film, the transistor 103 and the capacitor element 105 (MOS capacitor) can be electrically Fluctuations in characteristics can be suppressed.

[0124] The pixel electrode 121 is made of indium tin oxide, indium oxide containing tungsten oxide, Indium zinc oxide with tungsten oxide, indium oxide with titanium oxide, acid Indium tin oxide containing titanium dioxide, indium zinc oxide, indium with silicon dioxide added The insulating layer 11 is formed of a light-transmitting conductive material such as sodium tin oxide.

[0125] The substrate 150 can be any base material that can be applied to the substrate 102 .

[0126] The light-shielding film 152 is also called a black matrix, and is used as a backlight in a liquid crystal display device. and suppression of light leakage from light source devices such as those mentioned above, and the prevention of color display using color filters. The light-shielding film 152 is provided to prevent a decrease in contrast due to color mixing. For example, a metal or a face can be used as a material having a light-shielding property. The light-shielding film 152 may be an organic resin containing a material such as a material for the transistor of the pixel 101. In addition to the above 103, a scanning line driver circuit 104, a signal line driver circuit 106 (see FIG. 1A), etc. It may be provided in an area other than the pixel section 100 .

[0127] In addition, a colored film having a function of transmitting light of a predetermined wavelength is provided between adjacent light-shielding films 152. Furthermore, an overcoat may be provided between the light-shielding film 152 and the colored film and the counter electrode 154. A coating film may be provided.

[0128] The counter electrode 154 is provided by appropriately using a material that can be applied to the pixel electrode 121 .

[0129] The alignment film 156 and the alignment film 158 are made of a commonly used material such as polyamide. It is possible.

[0130] The liquid crystal 160 may be a thermotropic liquid crystal, a low molecular weight liquid crystal, a high molecular weight liquid crystal, a polymer dispersed liquid crystal, Ferroelectric liquid crystals, antiferroelectric liquid crystals, etc. can be used. These liquid crystal materials can be used under certain conditions. Cholesteric phase, smectic phase, cubic phase, chiral nematic phase, etc. Indicates the directions, etc.

[0131] The liquid crystal 160 may be a liquid crystal that exhibits a blue phase without using an alignment film. is one of the liquid crystal phases, and when the temperature of cholesteric liquid crystal is increased, it changes from the cholesteric phase to the equilibrium phase. This is the phase that appears just before the transition to the rhombohedral phase. The blue phase appears only in a narrow temperature range. In order to improve the temperature range, a liquid crystal composition containing a chiral agent is used. is made of an organic resin, and the organic resin contains hydrogen or water, etc., Therefore, there is a risk that the electrical characteristics of the transistors in the semiconductor device may be deteriorated. By using a blue phase as the semiconductor layer 160, it is possible to obtain the semiconductor layer 160 according to one embodiment of the present invention without using an organic resin. Therefore, a highly reliable semiconductor device can be obtained.

[0132] The liquid crystal element 108 is configured to change the pixel electrode 12 based on the display mode of the liquid crystal element 108. The configuration may be changed as needed, for example, by changing the shape of the electrode 151 and the counter electrode 154, or by forming protrusions called ribs. It can be changed.

[0133] In the semiconductor device according to one embodiment of the present invention, the polarization axis of the polarizing member (polarizing substrate) is blocked. The display mode of the semiconductor device is controlled by applying a voltage. When the liquid crystal element 108 is not in the normal state, it does not transmit light from a light source device such as a backlight. By providing a leak black, the area where the light-shielding film 152 of the pixel 101 is provided can be reduced or eliminated. As a result, pixel densities of 200 ppi or more, or even 300 ppi or more, can be achieved. Even when each pixel is small, such as in a high-resolution display device, the aperture ratio can be improved. In addition, the aperture ratio can be further improved by using a light-transmitting capacitor element. Cut.

[0134] <Method for manufacturing semiconductor device> Next, a method for manufacturing the above semiconductor device will be described with reference to FIGS.

[0135] In this case, the scanning line driver of the semiconductor device is provided on the same substrate as the substrate on which the pixel section 100 is provided. The dual gate transistor 15 included in the operation circuit 104 is formed by a dual The process for forming the dual-gate transistor 15 is also described. The gate electrode 17a of the transistor 15 is made of the same material as the gate electrode 107a of the transistor 103. The gate insulating film 12 of the dual gate transistor 15 is It is formed of the same material as the gate insulating film 127. Oxidation of the dual gate transistor 15 The oxide semiconductor film 11 is formed of the same material as the oxide semiconductor film 111 of the transistor 103. The source electrode 19a and the drain electrode 13a of the dual gate transistor 15 are The source electrode 109a and the drain electrode 113a of the transistor 103 are made of the same material. The insulating films 29, 31, and 32 of the dual gate transistor 15 are These are the insulating films 129, 131, and 132 of the transistor 103, respectively. It is made of the same material as

[0136] First, the scanning line 107 including the gate electrode 107a and the capacitance line 115 are formed on the substrate 102. The insulating film 127 is formed later to cover the scanning lines 107 and the capacitance lines 115. The insulating film 126 is formed, and the oxide semiconductor film 11 is formed in the region of the insulating film 126 that overlaps with the scanning line 107. 1 is formed on the oxide semiconductor film 11 so as to overlap the region where the pixel electrode 121 is to be formed later. 9 is formed on the insulating film 126 (see FIG. 5(A)).

[0137] By carrying out this process, the gate electrode 17a of the dual gate transistor 15, A gate insulating film 12 and an oxide semiconductor film 11 can be formed (see FIG. 5(B)). .

[0138] The scanning lines 107 and the capacitance lines 115 are formed by forming a conductive film using the materials listed above. The conductive film can be formed by forming a mask on the conductive film and processing the conductive film using the mask. The film is formed using various methods such as vapor deposition, CVD, sputtering, and spin coating. The thickness of the conductive film is not particularly limited, and the time required for forming the conductive film and the desired resistance can be determined. The mask can be determined by taking into consideration the rate of light emission, etc. The conductive film can be processed by dry etching. This can be done by either or both of dry etching and wet etching.

[0139] The insulating film 126 is formed by using a material that can be applied to the gate insulating film 127 and by a CVD method or a sputtering method. The film can be formed by using various film formation methods such as a deposition method.

[0140] When gallium oxide is used for the gate insulating film 127, MOCVD (Metal Using the Organic Chemical Vapor Deposition (OCVD) method An insulating film 126 can be formed.

[0141] The oxide semiconductor film 111 and the oxide semiconductor film 119 are formed using any of the oxide semiconductors listed above. an oxide semiconductor film is formed, a mask is formed over the oxide semiconductor film, and a mask is used to form a mask on the oxide semiconductor film. The oxide semiconductor film can be formed by a sputtering method, a coating method, It can be formed by pulsed laser deposition, laser ablation, or the like. By using a printing method, the oxide semiconductor film 111 and the oxide semiconductor film 119 are isolated from each other. The oxide semiconductor film can be formed directly on the insulating film 126 by a sputtering method. When forming a plasma, the power supply for generating the plasma can be an RF power supply, an AC power supply, or Alternatively, a DC power supply or the like can be used as appropriate. The sputtering gas is a rare gas (typically Typically, an argon atmosphere, an oxygen atmosphere, or a mixed gas of a rare gas and oxygen is used as appropriate. In the case of a mixed gas of rare gas and oxygen, it is preferable to increase the gas ratio of oxygen to rare gas. The target may be appropriately selected depending on the composition of the oxide semiconductor film to be formed. The mask is, for example, a resist mask formed by a photolithography process. The oxide semiconductor film can be processed by dry etching and wet etching. This can be done by etching one or both of the two. The etching conditions (etching gas, etching solution, etching time, etc.) are adjusted to suit the material. Set the temperature etc. as appropriate.

[0142] After the oxide semiconductor film 111 and the oxide semiconductor film 119 are formed, heat treatment is performed. The semiconductor film 111 and the oxide semiconductor film 119 are preferably dehydrogenated or dehydrated. The temperature of the heat treatment is typically 150°C or higher and lower than the substrate distortion point, preferably 200°C. The temperature is preferably 300°C or higher and 450°C or lower, more preferably 300°C or higher and 450°C or lower. The treatment is performed on the oxide semiconductor film before it is processed into the oxide semiconductor film 111 and the oxide semiconductor film 119. It is also possible.

[0143] In this heat treatment, the heat treatment device is not limited to an electric furnace, and a medium such as heated gas may be used. It may also be a device that heats the workpiece by thermal conduction or thermal radiation from the workpiece. GRTA (Gas Rapid Thermal Anneal) equipment, LRTA (La RTA (Rapid Thermal Anneal) equipment, etc. The LRTA device can be used with a halogen lamp. lamps, metal halide lamps, xenon arc lamps, carbon arc lamps, high-pressure natri The treated object is irradiated with light (electromagnetic waves) emitted from lamps such as mercury lamps and high-pressure mercury lamps. The GRTA device is a device that uses high-temperature gas to perform heat treatment. do.

[0144] The heat treatment is carried out in nitrogen, oxygen, or ultra-dry air (with a water content of 20 ppm or less, preferably 1 ppm or less, preferably 10 ppb or less, or air), or rare gas (argon, helium, etc. The above-mentioned nitrogen, oxygen, ultra-dry air, or rare gas may be added to hydrogen, water, or the like. It is preferable that the material does not contain the above. After heating in an inert gas atmosphere, the material is heated in an oxygen atmosphere. The treatment time is set to 3 minutes to 24 hours.

[0145] In addition, between the substrate 102 and the scanning line 107, the capacitance line 115, and the gate insulating film 127 When a base insulating film is provided, the base insulating film may be made of silicon oxide, silicon oxynitride, or nitride. silicon oxide, silicon nitride, gallium oxide, hafnium oxide, yttrium oxide, The insulating film can be formed of aluminum nitride, aluminum oxynitride, or the like. As silicon nitride, gallium oxide, hafnium oxide, yttrium oxide, aluminum oxide By forming the layer using a material such as aluminum, impurities, typically alkali metals, water, and the like, can be removed from the substrate 102. The base insulating film can be formed by sputtering. The film can be formed by coating or CVD.

[0146] Next, an opening 123 is formed in the insulating film 126 to reach the capacitance line 115, and a gate insulating film 127 is formed. After forming the signal line 109 including the source electrode 109a, the drain electrode 113a is formed. The conductive film 113 electrically connects the oxide semiconductor film 119 to the capacitor line 115. A conductive film 125 is formed (see FIG. 5(B)).

[0147] By carrying out this process, the source electrode 19a of the dual gate transistor 15, A drain electrode 13a and a conductive film 16 can be formed (see FIG. 2(B)). When forming the opening 123, an opening reaching the capacitance line 115 is formed in the gate insulating film 12. The conductive film 16 can be formed in contact with the capacitance line 115 .

[0148] The opening 123 is formed so that a part of the region of the insulating film 126 that overlaps with the capacitance line 115 is exposed. The mask can be formed and processed using the mask. This processing can be performed in the same manner as the scanning lines 107 and the capacitance lines 115 .

[0149] The signal line 109, the conductive film 113, and the conductive film 125 are forming a conductive film using a material applicable to the conductive film 125, forming a mask on the conductive film; The mask and the processing can be performed by scanning lines. This can be done in the same way as the capacitor line 107 and the capacitor line 115.

[0150] Next, the oxide semiconductor film 111, the oxide semiconductor film 119, the signal line 109, the conductive film 113, An insulating film 128 is formed on the conductive film 125 and the gate insulating film 127, and an insulating film 128 is formed on the insulating film 128. An insulating film 130 is formed, and an insulating film 133 is formed on the insulating film 130 (see FIG. 6(A)). The insulating films 128, 130, and 133 are preferably formed in succession. By doing so, the interfaces of the insulating film 128, the insulating film 130, and the insulating film 133 This can prevent impurities from being mixed into the product.

[0151] The insulating film 128 is formed by using a material that can be applied to the insulating film 129 and is formed by a CVD method or a sputtering method. The insulating film 130 can be formed by various film formation methods such as a film deposition method. The insulating film 133 can be formed using a material applicable to the insulating film 132. It can be formed using:

[0152] When an oxide insulating film that has a low interface state with the oxide semiconductor film 111 is used as the insulating film 129, In this case, the insulating film 128 can be formed under the following conditions. As an example, a case where a silicon oxide film or a silicon oxynitride film is formed will be described. The formation conditions were as follows: the substrate was placed in a vacuum-evacuated processing chamber of a plasma CVD apparatus and heated to 180°C. The temperature is maintained at 200°C or higher and 400°C or lower, and more preferably 200°C or higher and 370°C or lower. The pressure in the processing chamber was increased to 20°C by introducing a silicon-containing deposition gas and an oxidizing gas. The pressure in the processing chamber is set to 40 Pa or more and 250 Pa or less, and more preferably 40 Pa or more and 200 Pa or less. This is a condition for supplying high frequency power to the electrodes provided in the

[0153] Typical examples of silicon-containing deposition gases are silane, disilane, trisilane, and fluoride. Oxidizing gases include oxygen, ozone, nitrous oxide, and nitrogen dioxide. There is.

[0154] In addition, by increasing the amount of oxidizing gas to the amount of silicon-containing deposition gas by 100 times or more, It is possible to reduce the hydrogen content in the insulating film 128 (insulating film 129) and Therefore, the number of dangling bonds contained in the insulating film 128 (insulating film 129) can be reduced. The oxygen that moves from the insulating film 130 (insulating film 131) moves to the insulating film 128 (insulating film 129). Since the insulating film 128 (insulating film) may be captured by the dangling bonds contained therein, 129) is reduced, at least the oxide semiconductor film The oxygen contained in the insulating film 130 (insulating film 131) can be efficiently transferred to the insulating film 111. By doing so, oxygen vacancies in the oxide semiconductor film 111 can be filled. The amount of hydrogen entering the oxide semiconductor film 111 can be reduced, and It is possible to reduce the oxygen vacancies that occur.

[0155] The insulating film 131 is an oxide insulating film containing the above-mentioned oxygen excess region or an oxygen insulating film having a stoichiometric composition. When the insulating film 130 is an oxide insulating film containing more oxygen than Here, the oxide insulating film can be formed using a silicon oxide film or a silicon oxynitride film. The formation conditions are as follows: The substrate placed in the processing chamber is heated to 180°C or higher and 260°C or lower, more preferably 180°C or lower. The temperature was kept at 230°C or higher, and the raw material gas was introduced into the processing chamber to reduce the pressure in the processing chamber to 10 The pressure is set to 0 Pa or more and 250 Pa or less, more preferably 100 Pa or more and 200 Pa or less. 0.17W / cm to the electrode installed in the room 2 More than 0.5W / cm 2 The following is more preferably is 0.25W / cm 2 More than 0.35W / cm 2 The following high frequency power is supplied: .

[0156] The source gas for the insulating film 130 can be a source gas that can be used to form the insulating film 128. Cut.

[0157] As a condition for forming the insulating film 130, a high frequency voltage of the above power density is applied in a processing chamber under the above pressure. By supplying power, the decomposition efficiency of the source gas in the plasma increases, and oxygen radicals increase. As the oxidation of the source gas progresses, the oxygen content in the insulating film 130 becomes higher than the stoichiometric composition. In addition, in the film formed at the above substrate temperature, the bonding strength between silicon and oxygen is Therefore, it is possible to remove some of the oxygen in the film by heat treatment in a later step. As a result, the oxygen content is greater than the stoichiometric composition, and the oxygen content is reduced by heating. In addition, an oxide insulating film from which some of the elements are released can be formed on the oxide semiconductor film 111. Therefore, in the process of forming the insulating film 130, the insulating film 128 is formed on the insulating film 128. The oxide semiconductor film 111 is protected by a protective film 128. As a result, high-frequency power with high power density is applied. Even when the insulating film 130 is formed using the above-mentioned compound, damage to the oxide semiconductor film 111 can be suppressed.

[0158] In addition, by increasing the thickness of the insulating film 130, the amount of oxygen released by heating is increased. Therefore, it is preferable that the insulating film 130 is thicker than the insulating film 128. By providing the insulating film 128, it is possible to improve the coverage even when the insulating film 130 is provided thickly. can.

[0159] The insulating film 132 can be formed by a sputtering method, a CVD method, or the like. When the insulating film 132 is formed using a nitride insulating film with a low hydrogen content, the insulating film 132 is formed under the following conditions: In this case, a silicon nitride film is used as the nitride insulating film. The formation conditions are as follows: The substrate is heated at a temperature of 80°C to 400°C, more preferably 200°C to 370°C. The pressure in the processing chamber is maintained at 100 Pa or more and 250 Pa or less by introducing the raw material gas into the processing chamber. a or less, preferably 100 Pa or more and 200 Pa or less, and an electrode provided in the processing chamber The purpose is to supply high frequency power to the

[0160] The source gas for the insulating film 132 is a deposition gas containing silicon, nitrogen, and ammonia. It is preferable to use the following gases. Typical examples of deposition gases containing silicon include silane, disilane, and the like. The nitrogen flow rate is different from the ammonia flow rate. The ratio is preferably 5 to 50 times, more preferably 10 to 50 times. By using ammonia as a source gas, the decomposition of silicon-containing deposition gas and nitrogen This is because ammonia can be decomposed by plasma energy or thermal energy. The energy generated by dissociation is used to break down the bonds and This is because it contributes to breaking down the bonds of nitrogen molecules. The silicon nitride film is formed to prevent the intrusion of impurities such as hydrogen and water from the outside. It is possible.

[0161] After forming at least the insulating film 130, a heat treatment is performed to form the insulating film 128 or the insulating film 13 Oxygen contained in the oxide semiconductor film 111 is transferred to the oxide semiconductor film 111. It is preferable that the heat treatment be performed so that oxygen vacancies in the oxide semiconductor film 111 and the oxide semiconductor film 112 are filled. The heat treatment for dehydrogenating or dehydrating the oxide semiconductor film 119 is performed as appropriate with reference to the details of the heat treatment. It is possible.

[0162] Next, the insulating film 128, the insulating film 130, and the insulating film 133 are An opening 117 reaching the conductive film 113 is formed, and the insulating film 129, the insulating film 131, and the insulating film 1 32, and then a pixel electrode 121 is formed on the opening 117 and the insulating film 132 (FIG. 6(B)). reference).

[0163] By carrying out this process, the insulating film 29 of the dual gate transistor 15, the insulating film 31, an insulating film 32, an opening 94, and a wiring 92 can be formed (see FIG. 2(B)). By this process, the capacitance line 115 and the dual gate transistor included in the scanning line driving circuit 104 are The wiring 92 including the back gate electrode of the transistor 15 is electrically connected through the conductive film 16. will be done.

[0164] The opening 117 can be formed in the same manner as the opening 123. A conductive film is formed using the above-listed materials so as to be in contact with the conductive film 113 through the opening 117, The conductive film can be formed by forming a mask over the conductive film and processing the conductive film using the mask. The mask and processing can be performed in the same manner as for the scanning line 107 and the capacitance line 115. can.

[0165] Next, an alignment film 158 is formed on the insulating film 132 and the pixel electrode 121, and then, on the substrate 150 A light-shielding film 152 is formed. In addition, a counter electrode 154 is formed so as to cover the light-shielding film 152. An alignment film 156 is formed on the counter electrode 154. A liquid crystal 160 is provided on the alignment film 158. The substrate 150 is provided on the substrate 102 so that the film 156 contacts the liquid crystal 160. The substrate 102 and the substrate 150 are fixed together by a clamping mechanism (not shown).

[0166] The alignment films 156 and 158 are formed by spin coating, printing, or the like using the above-mentioned materials. It can be formed by appropriately using various film forming methods.

[0167] The light-shielding film 152 is formed by sputtering using the above-listed materials, and is then removed using a mask. When a resin is used as the light-shielding film 152, the light-shielding film 152 can be formed by processing the resin. It can be formed by a lithography process.

[0168] The counter electrode 154 is formed by using a material that can be applied to the pixel electrode 121 and is deposited by a CVD method or a sputtering method. The film can be formed by using various film forming methods such as a coating method.

[0169] The liquid crystal 160 can be directly applied onto the alignment film 158 by a dispenser method (dropping method). After the substrate 102 and the substrate 150 are bonded together, the liquid crystal 16 is formed by using capillary action or the like. 0 may be injected. In addition, the liquid crystal 160 is provided with an alignment film 156 to facilitate alignment. It is also preferable to perform a rubbing process on the alignment film 158 .

[0170] Through the above steps, a semiconductor device according to one embodiment of the present invention can be manufactured (see FIG. 4). see).

[0171] <Variation 1> In the semiconductor device according to one embodiment of the present invention, a semiconductor The connection between the semiconductor film (specifically, the oxide semiconductor film) and the capacitance line can be changed as appropriate. For example, in order to further increase the aperture ratio, a structure in which the semiconductor film is in direct contact with the capacitance line without an intervening conductive film is used. It can be said that:

[0172] In the drawings showing the modified examples below, for clarity of the drawings, the substrate 150 and the light-shielding film 152, the counter electrode 154, the alignment film 156, the alignment film 158, and the liquid crystal 160 are omitted. .

[0173] This structure will be described with reference to Figures 7 and 8. Figure 7 is a top view of a pixel 141 of this structure. 8 is a cross-sectional view taken along dashed lines A1-A2 and B1-B2 in FIG. Here, the capacitance element 145, which is different from the capacitance element 105 described in FIGS. 3 and 4, will be described. 7 and 8, other configurations are the same as those in FIGS. The same is true.

[0174] In the pixel 141, the oxide semiconductor film 11 functions as one electrode of the capacitor 145. 9 is in direct contact with the capacitance line 115 at the opening 143. In this way, the oxide semiconductor film 119 and the capacitor line 115 are in direct contact with each other without the conductive film 125 therebetween. Therefore, the conductive film 125 that serves as a light-shielding film is not provided, and therefore the aperture ratio of the pixel 141 can be further increased. can be done.

[0175] In the semiconductor device according to one embodiment of the present invention, a semiconductor film is in direct contact with a capacitance line. In the case of the semiconductor device, no opening is provided in the gate insulating film, and a region is provided in which a part of the capacitance line and the substrate are exposed. 9 is a top view of a pixel 101 having this structure, and FIG. 10 is a diagram showing a point in FIG. 10 is a cross-sectional view taken along dashed lines A1-A2 and dashed dotted lines B1-B2.

[0176] 9 and 10, the pixel 101 of this structure has a part of the gate insulating film 127 removed. A portion of each of the capacitor line 115 and the substrate 102 is exposed. In this region, the capacitor line 115 and the oxide semiconductor film 119 are in direct contact with each other. This allows the area where the capacitor line 115 and the oxide semiconductor film 119 are in contact to be increased. Therefore, the aperture ratio can be increased and the capacitance element 146 can be easily brought into a conductive state. It is possible.

[0177] <Variation 2> In the semiconductor device according to one embodiment of the present invention, one electrode of a capacitor may be The conductive film electrically connecting the semiconductor film (specifically, oxide semiconductor film) and the capacitance line is For example, to increase the conductivity of the semiconductor film, the conductive film can be provided along the periphery of the semiconductor film in contact with it. 11 and 12. Here, the conductive film 12 described with reference to FIGS. Only the conductive film 167, which is different from that in FIG. 5, will be described. 12(A) is a cross-sectional view taken along dashed lines A1-A2 and B1-B2 in FIG. 12B is a cross-sectional view taken along the dashed line D1-D2 in FIG.

[0178] In the pixel 161, the conductive film 167 is in contact with the outer periphery of the oxide semiconductor film 119. The conductive film 1 is provided in contact with the capacitor line 115 through the opening 123 (see FIG. 11). 67 is a signal line 109 including the source electrode 109a of the transistor 103 and a transistor The conductive film 113 that functions as the drain electrode 113a (not shown) of the component 103 is formed by the same process. Since the film is formed in a loop shape, it may have a light-shielding property. stomach.

[0179] As shown in FIGS. 12A and 12B, in a pixel 161 having this configuration, the conductive film 1 The insulating film 67 is provided to cover an end portion of the oxide semiconductor film 119 of the capacitor 105. The other configurations of the pixel 161 in FIGS. 11 and 12 are the same as those in FIGS.

[0180] 11 and 12, the conductive film 167 is formed in a loop shape. However, the entire portion of the conductive film 167 that is in contact with the oxide semiconductor film 119 is the capacitor line 11 5. In other words, it is not necessary to electrically connect the conductive film 167 to the conductive film 5. The conductive film 167 is provided in contact with the oxide semiconductor film 119 and is separated from the conductive film 167. It may also be used.

[0181] <Variation 3> In the semiconductor device according to one embodiment of the present invention, one electrode of a capacitor may be The connection between the semiconductor film (specifically, the oxide semiconductor film) and the capacitance line can be changed as needed. A specific example of this structure will be described with reference to FIGS. 13 and 14. 4. The oxide semiconductor film 119 and the capacitor line 115 are different from those described with reference to FIG. 13 is a top view of the pixel 171, and the capacitance line 175. The line 175 is provided so as to extend in a direction parallel to the signal line 109. The capacitor line 175 is electrically connected to the signal line driving circuit 106 (see FIG. 1(A)). .

[0182] The capacitance element 173 is connected to a capacitance line 175 extending in a direction parallel to the signal line 109. The capacitor 173 is formed by utilizing the formation process of the oxide semiconductor film 111. A light-transmitting oxide semiconductor film 177, a light-transmitting pixel electrode 121, and a dielectric film 13. The insulating film (not shown in FIG. 13) included in the transistor 103 has a light-transmitting property. That is, the capacitor 173 has a light-transmitting property.

[0183] Next, cross-sectional views taken along dashed lines A1-A2 and B1-B2 in FIG. Shown in 14.

[0184] In the capacitor 173, one of a pair of electrodes is an oxide semiconductor film 177. The other electrode of the pair of electrodes is a pixel electrode 121, and a dielectric layer provided between the pair of electrodes The conductive films are the insulating films 129, 131, and 132.

[0185] The capacitance line 175 can be formed by utilizing the process for forming the signal line 109 and the conductive film 113. By providing the capacitor line 175 in contact with the oxide semiconductor film 177, The contact area between the oxide semiconductor film 177 and the capacitor line 175 can be increased. can easily function as one electrode of the capacitor 173.

[0186] 13, the pixel 171 has a length in the direction in which the signal line 109 extends, which is longer than the length of the scanning line 107. 15. As shown in FIG. 15, the pixel 172 has a shape in which the length in the extension direction is longer than the length in the extension direction. The length of the scanning line 107 in the extension direction is longer than the length of the scanning line 109 in the extension direction. In addition, the capacitance line 176 may be provided extending in a direction parallel to the signal line 109. The signal line 109 and the capacitance line 176 are electrically connected to the signal line driver circuit 106 (see FIG. 1A). is connected.

[0187] The capacitance element 174 is connected to a capacitance line 176 extending in a direction parallel to the signal line 109. The capacitor 174 is formed by utilizing the formation process of the oxide semiconductor film 111. A light-transmitting oxide semiconductor film 178, a light-transmitting pixel electrode 121, and a dielectric film 15. The insulating film (not shown in FIG. 15) included in the transistor 103 has a light-transmitting property. That is, the capacitor 174 has a light-transmitting property.

[0188] Next, cross-sectional views taken along dashed lines A1-A2 and B1-B2 in FIG. Shown in 16.

[0189] The capacitor 174 has a pair of electrodes, one of which is an oxide semiconductor film 178. The other electrode is a pixel electrode 121, and a dielectric film provided between the pair of electrodes are the insulating films 129, 131, and 132.

[0190] The capacitance line 176 can be formed by utilizing the process for forming the signal line 109 and the conductive film 113. By providing the capacitor line 176 in contact with the oxide semiconductor film 178, It is possible to increase the contact area between the pixel 172 and the capacitor line 176. In this case, the length of the scanning line 107 in the extension direction is longer than the length of the signal line 109 in the extension direction. 13. Therefore, compared with the pixel 171 shown in FIG. The overlapping area can be reduced, and the aperture ratio can be improved.

[0191] <Variation 4> In addition, in the above-mentioned pixels 101, 141, 161, 171, and 172, , a parasitic capacitance occurring between the pixel electrode 121 and the conductive film 113, or a parasitic capacitance occurring between the pixel electrode 121 and the conductive film In order to reduce the parasitic capacitance occurring between the capacitor 125 and the capacitor 125, the parasitic capacitance is An organic insulating film 134 can be provided in the region where the amount of the organic insulating film 134 is generated. The configuration other than the insulating film 134 is the same as that shown in FIG. Only the organic insulating film 134 will be described.

[0192] The organic insulating film 134 may be made of a photosensitive or non-photosensitive organic resin, for example, acrylic. resin, benzocyclobutene resin, epoxy resin, siloxane resin, etc. The organic insulating film 134 can be made of polyamide.

[0193] The organic insulating film 134 is an organic resin film formed using the materials listed above. The organic insulating film 134 can be formed by processing the organic resin. This eliminates the need for a resist mask when forming the organic insulating film 134, simplifying the process. Therefore, the method for forming the organic insulating film is not particularly limited, and can be appropriately selected depending on the material used. For example, CVD, sputtering, spin coating, dipping, spraying Applying coating, droplet ejection method (inkjet method), screen printing, offset printing, etc. It is possible.

[0194] Generally, organic resin contains a large amount of hydrogen and water, and the organic resin is When the organic resin is provided on the oxide semiconductor film 111, hydrogen and water contained in the organic resin are absorbed by the transistor. The oxide semiconductor film 111 is diffused into the transistor 103 (particularly the oxide semiconductor film 111), and the electrical characteristics of the transistor 103 are deteriorated. Therefore, at least the insulating film 132 overlapping with the oxide semiconductor film 111 In other words, it is preferable that the organic insulating film 134 is not provided on the oxide semiconductor. It is preferable to remove the organic resin film on the region overlapping the conductive film 111 in advance.

[0195] A top view of the pixel 101 shown in FIG. 17 is shown in FIG. 18. The cross-sectional view of FIG. 17 is taken at a point Corresponding to the cross section between dashed lines A1-A2, dashed lines B1-B2, and dashed lines C1-C2 In FIG. 18, the organic insulating film 134 is not shown for clarity, but is indicated by a two-dot chain line. The region within is a region where the organic insulating film 134 is not provided.

[0196] <Variation 5> In the semiconductor device according to one embodiment of the present invention, one electrode constituting a capacitor and a capacitor The wires can be made of a semiconductor film (specifically, an oxide semiconductor film). Note that the oxide semiconductor film 119 and the capacitor line 115 described with reference to FIG. Only the oxide semiconductor film 198, which is different from the pixel 19, will be described. 6, an oxide semiconductor film 198 is provided which serves as one electrode of a capacitor element 197 and also as a capacitor line. In the oxide semiconductor film 198, a region extending in a direction parallel to the signal line 109 The oxide semiconductor film 198 has a pixel electrode 1 The region overlapping with the oxide semiconductor 21 functions as one electrode of the capacitor 197. When an electric field is applied to the film 198, the maximum depletion layer width becomes extremely wide, and the film 198 becomes conductive.

[0197] The oxide semiconductor film 198 is the oxide semiconductor of the transistor 103 provided in the pixel 196. It can be formed by utilizing the process for forming the conductive film 111.

[0198] The oxide semiconductor film 198 is formed so as to overlap with the scan line 107 in each of the pixels 196. That is, one oxide semiconductor film can be provided for all the pixels 196 in one row. The oxide semiconductor film can be provided as a continuous film without any gap therebetween.

[0199] In addition, the oxide semiconductor film 198 is formed in a continuous oxide film without being spaced apart in all the pixels 196 in one row. When the oxide semiconductor film 198 is provided as an oxide semiconductor film, the oxide semiconductor film 198 overlaps with the scan line 107. The potential change of the scanning line 107 is sufficient to make the scanning line 107 function as a capacitance line and one electrode of the capacitance element 197. Therefore, the oxide semiconductor film 198 may not function properly as shown in FIG. In the pixel 196, the oxide semiconductor films are provided at a distance from each other. and a conductive film 199 that can be formed by utilizing the formation process of the conductive film 113. It is preferable that

[0200] In FIG. 19, the region of the oxide semiconductor film 198 that functions as a capacitor line is parallel to the signal line 109. However, the area functioning as a capacitance line is extended in a direction parallel to the scanning line 107. Note that the region of the oxide semiconductor film 198 that functions as a capacitance line may be the same as the scanning line 1. In the case where the transistor 103 and the capacitor 197 are arranged in a direction parallel to the direction of the wiring 107, In the above, the oxide semiconductor film 111, the oxide semiconductor film 198, the signal line 109, and the conductive film It is necessary to provide an insulating film between them and 113 to electrically isolate them.

[0201] As described above, as in the pixel 196, one electrode of the capacitor element and the capacitor line provided in the pixel are By providing a light-transmitting oxide semiconductor film, the aperture ratio of a pixel can be improved. .

[0202] <Variation 6> In addition, in the semiconductor device according to one embodiment of the present invention, the configuration of the capacitance line can be changed as appropriate. This structure will be explained with reference to FIG. 20. The difference compared to the capacitance line 115 is that the capacitance line is located between two adjacent pixels. .

[0203] FIG. 20 shows the upper portions of the pixel 401_1 and the pixel 401_2 adjacent to each other in the extension direction of the signal line 409. FIG.

[0204] The scanning line 407_1 and the scanning line 407_2 are parallel to each other and connected to the signal line 409. The scanning lines 407_1 and 407_2 are arranged to extend in directions substantially perpendicular to each other. A capacitance line 415 is provided in parallel to the scanning line 407_1 and the scanning line 407_2. Note that the capacitor line 415 is connected to the capacitor 405_1 provided in the pixel 401_1 and the The pixel 401_1 and the pixel 401_2 are connected to the capacitor 405_2 provided in the pixel 401_1 and the pixel 401_2. The top surface shape of the capacitor _2 and the arrangement positions of the components are symmetrical with respect to the capacitor line 415.

[0205] The pixel 401_1 includes a transistor 403_1 and a transistor connected to the transistor 403_1. A capacitor 405_1 is provided.

[0206] The transistor 403_1 is provided in a region where the scanning line 407_1 and the signal line 409 intersect. The transistor 403_1 is a semiconductor having at least a channel formation region. a film 411_1, a gate electrode, a gate insulating film (not shown in FIG. 20), a source electrode, and a drain electrode. The overlapping region functions as the gate electrode of the transistor 403_1. The region overlapping with the semiconductor film 411_1 functions as a source electrode of the transistor 403_1. In the conductive film 413_1, a region overlapping with the semiconductor film 411_1 is a transistor. The conductive film 413_1 and the pixel electrode 421_1 function as a drain electrode of the pixel electrode 403_1. The connection is made at the opening 417_1.

[0207] The capacitor 405_1 is connected to the capacitor line 415 through a conductive film 425 provided in an opening 423. The capacitor 405_1 is formed using a light-transmitting oxide semiconductor. a semiconductor film 419_1, a pixel electrode 421_1 having light-transmitting properties, and a dielectric film The insulating film (not shown in FIG. 20) is included in the transistor 403_1 and has light-transmitting properties. That is, the capacitor 405_1 has a light-transmitting property.

[0208] The pixel 401_2 has a transistor 403_2 and a transistor connected to the transistor 403_2. A capacitor 405_2 is provided.

[0209] The transistor 403_2 is provided in a region where the scanning line 407_2 and the signal line 409 intersect. The transistor 403_2 is a semiconductor having at least a channel formation region. film 411_2, a gate electrode, a gate insulating film (not shown in FIG. 20), and a source electrode. In addition, the scan line 407_2 includes the semiconductor film 411_2 and the drain electrode. The overlapping region functions as a gate electrode of the transistor 403_2. The region overlapping with the semiconductor film 411_2 serves as the source electrode of the transistor 403_2. In the conductive film 413_2, a region overlapping with the semiconductor film 411_2 functions as a transistor. The conductive film 413_2 and the pixel electrode 421_2 function as a drain electrode of the pixel electrode 403_2. are connected at the opening 417_2.

[0210] The capacitor 405_2 is formed by a conductive film provided in the opening 423, similarly to the capacitor 405_1. The capacitor 405_2 is electrically connected to the capacitor line 415 through a light-transmitting a semiconductor film 419_2 formed of an oxide semiconductor having a light-transmitting property, and a pixel electrode 42 1_2, and a light-transmitting insulating film ( 20) and the capacitor 405_2 has a light-transmitting property.

[0211] Note that the transistor 403_1, the transistor 403_2, and the capacitor 405_ The cross-sectional structures of the transistor 103 and the capacitor 405_2 are the same as those of the transistor 103 and the capacitor 405_2 shown in FIG. Since it is similar to the quantum element 105, its description is omitted here.

[0212] In the top view, a capacitance line is provided between two adjacent pixels, and the capacitance included in each pixel is By connecting the capacitance elements and the capacitance lines, it is possible to reduce the number of capacitance lines. As a result, it is possible to further increase the aperture ratio of the pixel compared to a structure in which a capacitance line is provided for each pixel. For example, in a semiconductor device according to one embodiment of the present invention, the size of one pixel is 28 μm. The pixel density is 302 ppi. The pixel layout is shown in Figure 2. By using the layout shown in FIG. 0, the aperture ratio of the pixel can be set to 61.7%.

[0213] <Variation 7> The above-mentioned pixels 101, 141, 161, 171, 172, and 196, In the pixel 401_1 and the pixel 401_2, the shape of the transistor provided in the pixel is The shape of the transistor is not limited to that shown in FIGS. 3 and 4 and can be changed as appropriate. For example, in the pixel 151, the transistor 169 is connected to a source electrode included in the signal line 109. 109a (not shown) is U-shaped (C-shaped, U-shaped, or horseshoe-shaped), and the drain electrode Even if the transistor has a shape surrounding the conductive film 113 that functions as 113a (not shown), By using this shape, even if the area of ​​the transistor is small, It is possible to secure a sufficient channel width, and increase the amount of on-current of the transistor. 21. Other configurations of the pixel 151 in FIG. 21 are the same as those in FIG.

[0214] <Variation 8> Furthermore, the above-mentioned pixels 101, 141, 161, 171, 172, and 1 96, in the pixel 401_1 and the pixel 401_2, the transistor is Between the gate insulating film and the signal line including the source electrode and the conductive film functioning as the drain electrode The transistor is located at the oxidized The compound semiconductor film 195 is connected to the signal line 191 including the source electrode 191a and the drain electrode 193a. The conductive film 193 functions as a transistor 190 located between the insulating film 129. 22, the structure other than the position of the oxide semiconductor film 195 is the same as that in FIG. is the same as

[0215] The transistor 190 shown in FIG. 22 is formed by forming a signal line 191 and a conductive film 193, and then Therefore, the surface of the oxide semiconductor film 195 is 1 and the conductive film 193 are not exposed to the etchant or etching gas used in the forming process, and are not oxidized. The impurities between the compound semiconductor film 195 and the insulating film 129 can be reduced. In order to reduce the leakage current flowing between the source electrode 191a and the drain electrode 193a of the semiconductor device 190, It is possible.

[0216] <Variation 9> Furthermore, the above-mentioned pixels 101, 141, 161, 171, 172, and 1 96, in the pixel 401_1 and the pixel 401_2, as a transistor, a channel edge The transistor has a channel structure as shown in FIG. 23, an oxide semiconductor transistor 183 can be used. The conductive film 111, the signal line 109 including the source electrode 109a, and the drain electrode 113a The structure is the same as that of the conventional semiconductor device except that a channel protection film 182 is provided between the conductive film 113 that functions as a channel protection film. Same as Figure 4.

[0217] The channel-protective transistor 183 illustrated in FIG. 23 has a channel formed on an oxide semiconductor film 111. After forming the channel protection film 182, the signal line 109 and the conductive film 113 are formed. The protective film 182 can be formed from the material of the insulating film 129 of the transistor 103. By doing so, in the channel protection transistor 183, There is no need to provide an insulating film corresponding to the insulating film 129. The surface of 111 is etched with an etchant or an etchant used in the process of forming the signal line 191 and the conductive film 193. The impurities between the oxide semiconductor film 111 and the channel protective film 182 are removed without being exposed to the fluorine gas. As a result, the source electrode 109a and It is possible to reduce the leakage current flowing between the drain electrodes 113a. By providing the panel protective film 182, the processing performed when forming the signal line 109 and the conductive film 113 can be performed. This prevents damage to the oxide semiconductor film 111 (particularly, the channel formation region). It can be controlled.

[0218] <Modification 10> Furthermore, the above-mentioned pixels 101, 141, 161, 171, 172, and 1 96, in the pixel 401_1 and the pixel 401_2, one gate as a transistor Although a transistor having electrodes has been shown, it is possible to use an oxide semiconductor instead, as shown in FIG. The conductive film 187 faces the gate electrode included in the scanning line 107 via the conductive film 111. A transistor 185 can be used.

[0219] The transistor 185 is the same as the transistor 103 and the transistor 104 described in this embodiment. 69, a dual gate transistor having a conductive film 187 on an insulating film 132 of a transistor 190 The conductive film 187 can be said to be a back gate electrode. The conductive film 187 also overlaps with the channel formation region of the oxide semiconductor film 111. By providing the transistor 11 at a position overlapping the channel forming region, reliability tests (e.g., BT Transistor 185 before and after (Bias Temperature) stress test The amount of fluctuation in the threshold voltage can be further reduced. The conductive film 187 may be set to a common potential, a GND potential, or any other potential. In addition, the potential of the conductive film 187 can be controlled to change the transistor. The threshold voltage of the gate electrode 107a and the conductive film 185 can be controlled. By providing the conductive film 187, the surrounding electric potential can be The influence of the change in the field on the oxide semiconductor film 111 is reduced, and the reliability of the transistor is improved. It can be done.

[0220] The conductive film 187 is made of the same material as the scanning lines 107, the signal lines 109, the pixel electrodes 121, etc. It can be formed by the method.

[0221] As described above, in a semiconductor device having a driver circuit, a transistor included in the driver circuit a back gate electrode of a dual gate transistor; By electrically connecting the capacitor element to the capacitor line, power consumption is reduced. The operating speed of the driving circuit can be increased while maintaining the high image quality, thereby providing a semiconductor device with excellent display quality. It is possible.

[0222] In addition, a semiconductor film (specifically, an oxide semiconductor film) of a transistor is used as one electrode of the capacitor. By using a semiconductor film formed in the same process as the charge carrier film, the aperture ratio can be increased while As a result, a semiconductor device having a capacitor element with an increased capacitance can be manufactured. Therefore, a semiconductor device with excellent properties can be obtained.

[0223] Furthermore, oxygen vacancies in a semiconductor film (specifically, an oxide semiconductor film) of a transistor are reduced, Since impurities such as hydrogen and nitrogen are reduced, the semiconductor device according to one embodiment of the present invention can be The semiconductor device has excellent electrical characteristics.

[0224] Note that the structure described in this embodiment mode may be appropriately combined with structures described in other embodiments. It can be used.

[0225] (Embodiment 2) This embodiment describes a semiconductor device according to one embodiment of the present invention, which has a structure different from that of the above embodiment. The semiconductor device will be described with reference to the drawings. In this embodiment, a liquid crystal display device will be used as an example. In addition, the semiconductor device described in this embodiment will be described. The device has a different structure of the capacitance element compared to the above embodiment. In the semiconductor device, the same structure as the semiconductor device described in the above embodiment is Reference can be made to the embodiments.

[0226] <Configuration of semiconductor device> A top view of the pixel 201 described in this embodiment is shown in FIG. 25. 1 is different from the pixel 101 shown in FIG. 3 in that the insulating film 229 ( 25. Therefore, the insulating film 231 (not shown) is not provided. The capacitor 205 of the element 201 has an oxide semiconductor film 119 functioning as one electrode and a The pixel electrode 221 is an electrode of the pixel electrode 221, and the insulating film 232 (not shown) is a dielectric film. are.

[0227] Next, cross-sectional views taken along dashed lines A1-A2 and B1-B2 in FIG. 25 are shown. Shown in Figure 26.

[0228] The cross-sectional structure of the pixel 201 in this embodiment is as follows. The scanning line 107 includes a port electrode 107a, and a capacitor provided on the same surface as the scanning line 107. A gate insulating film 127 is formed on the scanning line 107 and the capacitance line 115. An oxide semiconductor is provided on a region of the gate insulating film 127 that overlaps with the scan line 107. The oxide semiconductor film 119 is provided over the gate insulating film 127. A source electrode 109a is formed over the oxide semiconductor film 111 and the gate insulating film 127. A signal line 109 including the signal line 109 and a conductive film 113 functioning as a drain electrode 113a are provided. The gate insulating film 127 has an opening 123 that reaches the capacitor line 115. 23, a conductive film 125 is provided over the gate insulating film 127 and the oxide semiconductor film 119. The gate insulating film 127, the signal line 109, the oxide semiconductor film 111, and the conductive film 113 are A protective insulating film for the transistor 103 is formed on the conductive film 125 and the oxide semiconductor film 119. The insulating film 229, the insulating film 231, and the insulating film 232 are provided. 9, an opening 117 reaching the conductive film 113 is provided in the insulating film 231 and the insulating film 232. The pixel electrode 221 is provided on the opening 117 and the insulating film 232. Between the gate insulating film 127 and the scanning line 107 and the capacitance line 115, an underlying insulating film is formed. may be provided.

[0229] The insulating film 229 is the same as the insulating film 129 described in the first embodiment. 231 is an insulating film similar to the insulating film 131 described in the first embodiment. The insulating film is the same as the insulating film 132 described in the first embodiment. This pixel electrode is the same as the pixel electrode 121 described in the first embodiment.

[0230] As in the capacitor 205 in this embodiment, an oxide semiconductor serving as one electrode The dielectric film provided between the dielectric film 119 and the pixel electrode 221, which is the other electrode, is called an insulating film 23. 2, the thickness of the dielectric film is set to be the same as that of the dielectric film of the capacitor element 105 in the first embodiment. Therefore, the capacitor element 205 in this embodiment can be made thinner than the The charge capacity can be increased compared to the capacitor 105 in the first embodiment.

[0231] The insulating film 232 is a nitride insulating film, similar to the insulating film 132 of the first embodiment. Since the insulating film 232 is in contact with the oxide semiconductor film 119, it is preferable that the nitride insulating film Nitrogen and / or hydrogen contained in the oxide semiconductor film 119 can be transferred to the oxide semiconductor film 119. It is possible to increase the conductivity of the conductor film 119. In addition, the insulating film 232 is a nitride insulating film. By performing heat treatment while the insulating film 232 is in contact with the oxide semiconductor film 119, the nitride Nitrogen and / or hydrogen contained in the insulating film can be moved to the oxide semiconductor film 119. As a result, the conductivity of the oxide semiconductor film 119 increases, and the oxide semiconductor film 119 becomes n-type. Since the oxide semiconductor film 119 has higher conductivity than the oxide semiconductor film 111, the oxide semiconductor film 119 has higher conductivity than the oxide semiconductor film 111. It can be said that the film has such properties.

[0232] As described above, in the semiconductor device of this embodiment, the oxide semiconductor film 119 is an oxide The oxide semiconductor film 119 has a region having higher conductivity than the semiconductor film 111. The region of the oxide semiconductor film 111 in contact with the insulating film 232 is more conductive than the region of the oxide semiconductor film 111 in contact with the insulating film 229. The electricity rate is high.

[0233] Note that the oxide semiconductor film 119 preferably has a higher hydrogen concentration than the oxide semiconductor film 111. The oxide semiconductor film 119 is analyzed by secondary ion mass spectrometry (SIMS). The hydrogen concentration obtained by ion mass spectrometry (IMS) is x10 19 atoms / cm 3 or more, preferably 1 × 10 20 atoms / cm 3 That's all, More preferably, 5 × 10 20 atoms / cm 3 The oxide semiconductor film 111 The hydrogen concentration obtained by secondary ion mass spectrometry is 5×10 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 Less than 1 x 10 18 at oms / cm 3 Less than or equal to 5 × 10 17 atoms / cm 3 Below are some more preferred Or 1 x 10 16 atoms / cm 3 The following is the result.

[0234] The oxide semiconductor film 119 has a lower resistivity than the oxide semiconductor film 111. The resistivity of the oxide semiconductor film 119 is 1×10 -8 more than 1x10 - 1 It is preferable that the ratio is less than 1×10 -3 Ωcm or more 1×10 4 Ωcm not yet More preferably, the resistivity is less than 1×10 -3 Ωcm or more 1×10 -1 Less than Ωcm It is good.

[0235] <Method for manufacturing semiconductor device> Next, a manufacturing method of a semiconductor device in this embodiment mode will be described with reference to FIGS. and explain.

[0236] First, the scanning line 107 including the gate electrode 107a and the capacitance line 115 are formed on the substrate 102. The gate insulating film 127 is formed on the substrate 102, the scanning line 107, and the capacitance line 115. An insulating film is formed, and an oxide semiconductor film 111 and an oxide semiconductor film 119 are formed over the insulating film. Then, an opening 123 reaching the capacitance line 115 is formed in the insulating film to form a gate insulating film 127. After that, the signal line 109 including the source electrode 109a, the conductive film 113, and the conductive film 125 are formed. The gate insulating film 127, the signal line 109, the conductive film 113, the conductive film 125, and the oxide semiconductor An insulating film 128 is formed on the conductive film 119, and an insulating film 130 is formed on the insulating film 128 (FIG. 27(A)). The steps up to this point can be performed with reference to the first embodiment. .

[0237] Next, a mask is formed over at least a region of the insulating film 130 overlapping with the oxide semiconductor film 119. The mask is used to process the insulating film 228 and the insulating film 230, and the insulating film 228 and the insulating film 230 are formed. The compound semiconductor film 119 is exposed, and an insulating film 233 is formed on the exposed region and on the insulating film 130. (See FIG. 27(B)). The mask is a pattern formed by a photolithography process. A resist mask can be used, and the processing can be carried out by dry etching and wet etching. The insulating film 233 may be formed by one or both of the methods described in the first embodiment. This is an insulating film similar to the insulating film 133 described above. Heat treatment may be performed in the state where the film 233 is in contact with the oxide semiconductor film 119. The step in the above can also be carried out with reference to the first embodiment.

[0238] The insulating film 233 formed of a nitride insulating film is formed by a plasma CVD method or a sputtering method. When the oxide semiconductor film 119 is deposited, the oxide semiconductor film 119 is exposed to plasma, and oxygen vacancies are formed in the oxide semiconductor film 119. In addition, the oxide semiconductor film 119 and the insulating film 233 formed of a nitride insulating film are in contact with each other. As a result, nitrogen and / or hydrogen are transferred from the insulating film 233 to the oxide semiconductor film 119. When hydrogen contained in the insulating film 233 enters the oxygen vacancy, electrons, which act as carriers, are generated. Alternatively, the insulating film 232 may be a nitride insulating film and may be in contact with the oxide semiconductor film 119. By performing heat treatment in this state, nitrogen and / or hydrogen contained in the nitride insulating film are oxidized. As a result, the conductivity of the oxide semiconductor film 119 increases, In addition, the conductive film is made of a metal oxide film having conductive properties and has a light-transmitting property. The oxide semiconductor film 119 has higher conductivity than the oxide semiconductor film 111.

[0239] Next, an opening reaching the conductive film 113 is formed in the insulating film 228, the insulating film 230 and the insulating film 233. A hole 117 is formed, and an insulating film 229, an insulating film 231, and an insulating film 232 are formed (FIG. 28( A pixel electrode 221 is formed in contact with the conductive film 113 through the opening 117 (see FIG. 2A). 8(B)). The steps up to this point can also be carried out by referring to the first embodiment. Cut.

[0240] Through the above steps, the semiconductor device of this embodiment mode can be manufactured.

[0241] <Modification> In the semiconductor device according to one embodiment of the present invention, the structure of the capacitor can be changed as appropriate. A specific example of this structure will be described with reference to FIG. 29. Note that, here, the same structure as in FIGS. 3 and 4 will be described. Only the capacitor 245, which is different from the capacitor 205 described above, will be described.

[0242] The gate insulating film 218 is made of an insulating film 226 which is a nitride insulating film and an insulating film 227 which is an oxide insulating film. 27, and the insulating film 119 is formed at least in a region where the oxide semiconductor film 119 is provided. In this configuration, only the insulating film 226 is provided. The oxide semiconductor film 119 is in contact with the bottom surface of the oxide semiconductor film 119, and the conductivity of the oxide semiconductor film 119 is increased. (See FIG. 29.) FIG. 29 is a cross-sectional view, and a top view corresponding to FIG. 3 can be referred to. In this case, the dielectric film of the capacitor element 105 is the insulating film 129, the insulating The insulating film 131 and the insulating film 132 are the gate insulating film 226 and the insulating film 227. An insulating film applicable to the film 127 can be appropriately used. The insulating film 227 is the same as the insulating film 132. In order to achieve this configuration, the same insulating film may be used as in the first embodiment. The insulating film 227 may be processed.

[0243] In the structure illustrated in FIG. 29, the top surface of the oxide semiconductor film 119 is in contact with the insulating film 132. That is, in the configuration shown in FIG. 29, the insulating film 129 and the insulating film 1 The region of the capacitor 105 that is in contact with the oxide semiconductor film 119 may be removed. The dielectric film is an insulating film 132. The upper and lower surfaces of the oxide semiconductor film 119 are covered with a nitride insulating film. By adopting a structure in which the oxide is in contact with the nitride insulating film on only one side, the oxide can be formed more efficiently and sufficiently than when the oxide is in contact with the nitride insulating film on only one side. The conductivity of the semiconductor film 119 can be increased.

[0244] As described above, according to one embodiment of the present invention, in a semiconductor device including a driver circuit, The transistor to be used is a dual gate transistor, and the dual gate transistor the back gate electrode is electrically connected to a capacitance line electrically connected to the capacitance element. This allows the operating speed of the drive circuit to be increased while reducing power consumption, resulting in superior display quality. A semiconductor device having such a structure can be obtained.

[0245] In addition, a semiconductor film (specifically, an oxide semiconductor film) of a transistor is used as one electrode of the capacitor. By using a semiconductor film formed in the same process as the charge carrier film, the aperture ratio can be increased while It is possible to manufacture a semiconductor device having a capacitor element with an increased capacitance. By doing so, a semiconductor device with excellent display quality can be obtained.

[0246] Furthermore, oxygen vacancies in a semiconductor film (specifically, an oxide semiconductor film) of a transistor are reduced, Since impurities such as hydrogen and nitrogen are reduced, the semiconductor device according to one embodiment of the present invention can be The semiconductor device has excellent electrical characteristics.

[0247] The configurations shown in this embodiment may be applied to the configurations shown in other embodiments and their modifications. They can be used in any suitable combination.

[0248] (Embodiment 3) This embodiment describes a semiconductor device according to one embodiment of the present invention, which has a structure different from that of the above embodiment. The semiconductor device will be described with reference to the drawings. In this embodiment, a liquid crystal display device will be used as an example. In addition, the semiconductor device described in this embodiment will be described. The device is different from the above embodiment in the semiconductor film that is one electrode of the capacitor element. In the semiconductor device described in this embodiment, For a similar configuration, the above embodiment modes can be referred to.

[0249] <Configuration of semiconductor device> Specific configuration of a pixel 301 provided in a pixel portion of a liquid crystal display device described in this embodiment An example will be described. A top view of a pixel 301 is shown in FIG. 30. The pixel 301 shown in FIG. 30 has the following features: The pixel 301 includes a capacitor element 305, which is connected to the capacitor line 115 and the signal line 10. The capacitor element 305 is provided in the region surrounded by the conductive film 9. The capacitor element 305 is electrically connected to the capacitor line 115 through the capacitor 125. The oxide semiconductor film 319 has higher electrical conductivity than the oxide semiconductor film 111 and has a light-transmitting property. The pixel electrode 121 is a dielectric film, and the transistor 103 is a light-transmitting insulating film. 30). That is, the capacitor element 305 has a light-transmitting property. .

[0250] The conductivity of the oxide semiconductor film 319 is preferably 10 S / cm or more and 1000 S / cm or less. is between 100S / cm and 1000S / cm.

[0251] Since the oxide semiconductor film 319 has high conductivity, it can be used as an electrode for a capacitor. That is, the capacitance element 305 is formed large (large area) in the pixel 301. Therefore, it is possible to obtain a semiconductor device having an increased aperture ratio and an increased charge capacity. As a result, a semiconductor device with excellent display quality can be obtained.

[0252] Next, cross-sectional views taken along dashed lines A1-A2 and B1-B2 in FIG. Shown in Figure 31.

[0253] The cross-sectional structure of the pixel 301 is as follows: A gate insulating film 127 is provided on the scanning line 107. The oxide semiconductor film 111 is provided over a region of the gate insulating film 127 that overlaps with the scan line 107. An oxide semiconductor film 319 is provided over the gate insulating film 127. On the conductive film 111 and the gate insulating film 127, a signal line 109 including a source electrode 109a is formed. A conductive film 113 functioning as a drain electrode 113a is provided. The capacitor line 115 is provided over the insulating film 127 and the oxide semiconductor film 319. the oxide semiconductor film 127, the signal line 109, the oxide semiconductor film 111, the conductive film 113, and the oxide semiconductor The insulating film 119 functions as a protective insulating film for the transistor 103 and is formed on the capacitor line 115. 29, an insulating film 131, and an insulating film 132 are provided. The insulating film 132 has an opening 117 that reaches the conductive film 113. The pixel electrode 121 is provided on the insulating film 132. A base insulating film may be provided between the gate insulating film 07 and the gate insulating film 127.

[0254] In the capacitor 305 of this embodiment, one of a pair of electrodes is connected to an oxide semiconductor film 1 The other electrode of the pair of electrodes is an oxide semiconductor film 319 having a higher conductivity than the oxide semiconductor film 11. The element electrode 121 is a dielectric film provided between the pair of electrodes, and the insulating film 129 is an insulating film 13 1 and insulating film 132.

[0255] The oxide semiconductor film 319 is formed using an oxide semiconductor applicable to the oxide semiconductor film 111. The oxide semiconductor film 111 and the oxide semiconductor film 319 can be formed. Therefore, the oxide semiconductor film 319 can be formed by the oxide semiconductor contained in the oxide semiconductor film 111. The oxide semiconductor film 319 contains a conductive metal element. Since high conductivity is desirable, an element (dopant) that increases conductivity is included. Specifically, the oxide semiconductor film 319 preferably contains boron as a dopant. , nitrogen, fluorine, aluminum, phosphorus, arsenic, indium, tin, antimony and rare gases The oxide semiconductor film 319 contains one or more dopants selected from the group consisting of: The concentration is 1 x 10 19 atoms / cm 3 More than 1×10 22 atoms / cm 3 is In this way, it is preferable that the conductivity of the oxide semiconductor film 319 be 10 S / cm or less. or more and 1000 S / cm or less, preferably 100 S / cm or more and 1000 S / cm or less Therefore, the oxide semiconductor film 319 can function sufficiently as one electrode of the capacitor 305. Note that the oxide semiconductor film 319 has higher conductivity than the oxide semiconductor film 111. In this embodiment, at least the insulating film 1 of the oxide semiconductor film 319 The region of the oxide semiconductor film 111 in contact with the insulating film 129 has a higher electrical conductivity than the region of the oxide semiconductor film 111 in contact with the insulating film 129. In addition, the oxide semiconductor film 319 is n-type because it contains the above element (dopant). Because of its high conductivity, it can also be called a conductive film.

[0256] <Method for manufacturing semiconductor device> Next, a manufacturing method of a semiconductor device in this embodiment mode will be described with reference to FIGS. and explain.

[0257] First, the scanning line 107 including the gate electrode 107a and the capacitance line 115 are formed on the substrate 102. Then, an insulating film to be processed into a gate insulating film 127 is formed on the substrate 102, the scanning lines 107, and the capacitance lines. Then, an oxide semiconductor film 111 and an oxide semiconductor film 119 are formed over the insulating film (FIG. 32(A)). The steps up to this point can be performed with reference to the first embodiment. .

[0258] Next, a dopant was added to the oxide semiconductor film 119 to form an oxide semiconductor film 319. Thereafter, an opening 123 is formed in the insulating film 126 to reach the capacitance line 115, and a gate insulating film 127 is formed. After the formation of the gate electrode 109, the signal line 109 including the source electrode 109a and the drain electrode 113a are formed. a conductive film 113 that electrically connects the oxide semiconductor film 319 and the capacitor line 115; 5 is formed (see Figure 32(B)).

[0259] The method of adding a dopant to the oxide semiconductor film 119 is as follows. A mask is placed in the region, and boron, nitrogen, fluorine, aluminum, phosphorus are introduced using the mask. one or more dopants selected from the group consisting of arsenic, indium, tin, antimony and rare gas elements; The ions are added by ion implantation or ion doping. Instead of the doping method, the oxide semiconductor film 119 is exposed to plasma containing the dopant. The dopant may be added by performing a heat treatment after adding the dopant. The heat treatment may be performed on the oxide semiconductor film 111 and the oxide semiconductor film 112 described in Embodiment 1. The heat treatment for dehydrogenating or dehydrating the oxide semiconductor film 119 is performed as appropriate with reference to the details of the heat treatment. It is possible.

[0260] The dopant addition process is performed by adding the signal line 109, the conductive film 113, and the conductive film 125. In that case, the signal line 109 and the conductive film 1 The region in contact with the conductive film 125 and the conductive film 13 is not doped with dopant.

[0261] Next, the gate insulating film 127, the signal line 109, the oxide semiconductor film 111, the conductive film 113, and the conductive An insulating film 128 is formed over the oxide semiconductor film 125 and the oxide semiconductor film 319. An insulating film 130 is formed, and an insulating film 133 is formed on the insulating film 130 (see FIG. 33(A)). This step can be performed with reference to the first embodiment.

[0262] Next, an opening reaching the conductive film 113 is formed in the insulating film 128, the insulating film 130 and the insulating film 133. A hole 117 is formed, and an insulating film 129, an insulating film 131, and an insulating film 132 are formed (FIG. 33( 3B)), a pixel electrode 121 is formed in contact with the conductive film 113 through the opening 117 (see FIG. 3B). 1). This step can also be carried out by referring to the first embodiment.

[0263] Through the above steps, the semiconductor device of this embodiment mode can be manufactured.

[0264] As described above, according to one embodiment of the present invention, in a semiconductor device including a driver circuit, The transistor to be used is a dual gate transistor, and the dual gate transistor the back gate electrode is electrically connected to a capacitance line electrically connected to the capacitance element. This allows the operating speed of the drive circuit to be increased while reducing power consumption, resulting in superior display quality. A semiconductor device having such a structure can be obtained.

[0265] In addition, a semiconductor film (specifically, an oxide semiconductor film) of a transistor is used as one electrode of the capacitor. By using a semiconductor film formed in the same process as the charge carrier film, the aperture ratio can be increased while It is possible to manufacture a semiconductor device having a capacitor element with an increased capacitance. By doing so, a semiconductor device with excellent display quality can be obtained.

[0266] Furthermore, oxygen vacancies in a semiconductor film (specifically, an oxide semiconductor film) of a transistor are reduced, Since impurities such as hydrogen and nitrogen are reduced, the semiconductor device according to one embodiment of the present invention can be The semiconductor device has excellent electrical characteristics.

[0267] Note that the structure described in this embodiment mode may be appropriately combined with structures described in other embodiments. It can be used.

[0268] (Fourth embodiment) In this embodiment, a transistor included in the semiconductor device described in the above embodiment is and a capacitor element, and one embodiment that can be applied to an oxide semiconductor film that is a semiconductor film will be described. do.

[0269] Oxide semiconductor films are roughly classified into non-single-crystal oxide semiconductor films and single-crystal oxide semiconductor films. The non-single-crystal oxide semiconductor film is a CAAC-OS (C Axis Aligned Crystal Polycrystalline oxide semiconductor film The oxide semiconductor film includes a film, a microcrystalline oxide semiconductor film, an amorphous oxide semiconductor film, and the like.

[0270] First, the CAAC-OS film will be described.

[0271] The CAAC-OS film is one of the oxide semiconductor films that has multiple crystal parts aligned along the c-axis. .

[0272] The CAAC-OS film was observed under a transmission electron microscope (TEM). When observed under a tron ​​microscope, clear boundaries between the crystals are observed. It is not possible to confirm the grain boundary. It can be said that the AAC-OS film is less susceptible to the decrease in electron mobility caused by grain boundaries.

[0273] The CAAC-OS film was observed by TEM from a direction roughly parallel to the sample surface (cross-sectional TEM observation). When observed, it can be confirmed that metal atoms are arranged in layers in the crystalline part. Each layer of the CAAC-OS film is formed on a surface (also called a surface to be formed) or on a concave surface of the upper surface. The shape reflects the convexity and is aligned parallel to the surface on which the CAAC-OS film is formed or the upper surface.

[0274] In this specification, "parallel" means that two straight lines are at an angle of -10° or more and 10° or less. This means that the angle is between -5° and 5°. "Perpendicular" means that two straight lines are arranged at an angle of 80° or more and 100° or less. Therefore, the angle may be between 85° and 95°.

[0275] On the other hand, the CAAC-OS film was observed by TEM from a direction approximately perpendicular to the sample surface (plane T EM observation reveals that metal atoms are arranged in triangular or hexagonal shapes in the crystalline region. However, no regularity was observed in the arrangement of metal atoms between different crystal regions. do not have.

[0276] Cross-sectional and planar TEM observations revealed that the crystals in the CAAC-OS film had an orientation. It can be seen that this is the case.

[0277] Most of the crystals in the CAAC-OS film are cubic crystals with sides of less than 100 nm. Therefore, the crystal part in the CAAC-OS film has a side length of 10 This also includes cases where the size fits within a cube of less than 5 nm, or less than 3 nm. However, multiple crystals in the CAAC-OS film are connected to form a single large crystal domain. For example, in a planar TEM image, 2 Over 5μm 2 More than or equal to 1000 μm 2 Crystal regions with more than this size may be observed.

[0278] X-ray diffraction (XRD) of the CAAC-OS film When structural analysis is performed using this device, for example, CAAC-OS with InGaZnO4 crystals can be seen. In the out-of-plane analysis of the film, the diffraction angle (2θ) peaks around 31°. This peak is attributed to the (009) plane of the InGaZnO4 crystal. Therefore, the crystals of the CAAC-OS film have a c-axis orientation, and the c-axis faces the surface on which the film is formed or the upper surface. It can be seen that the direction is roughly vertical.

[0279] On the other hand, the in-p X-rays incident on the CAAC-OS film are perpendicular to the c-axis. In the Lane analysis, a peak may appear around 2θ of 56°. The crystal structure of InGaZnO4 is composed of a single crystal of InGaZnO4. In the case of a nitride semiconductor film, 2θ is fixed at around 56°, and the normal vector of the sample surface is the axis (φ axis). When the sample is rotated and analyzed (φ scan), a crystal plane equivalent to the (110) plane is detected. In contrast, in the case of the CAAC-OS film, six peaks are observed, which are assigned to 2θ. Even when the φ is fixed at around 56° and scanned, no clear peak appears.

[0280] From the above, it can be concluded that the orientation of the a-axis and b-axis is uniform between different crystal regions in the CAAC-OS film. Although it is irregular, it has a c-axis orientation, and the c-axis is parallel to the normal vector of the surface on which it is formed or the upper surface. Therefore, the layered structure confirmed by the cross-sectional TEM observation mentioned above is consistent with the Each layer of arranged metal atoms is a plane parallel to the ab plane of the crystal.

[0281] The crystalline part is formed when the CAAC-OS film is formed or after a crystallization treatment such as a heat treatment. As described above, the c-axis of the crystal is aligned with the surface on which the CAAC-OS film is to be formed. Therefore, for example, in the CAAC-OS film, When the shape is changed by etching, the c-axis of the crystal is aligned with the CAAC-OS film. It may not be parallel to the normal vector of the face or top surface.

[0282] Furthermore, the distribution of c-axis oriented crystals in the CAAC-OS film does not need to be uniform. For example, the crystalline part of the CAAC-OS film is grown from the top surface of the CAAC-OS film. Therefore, when the crystal is formed, the region near the top surface has a crystal orientation that is more c-axis oriented than the region near the surface on which the crystal is formed. In addition, when impurities are added to the CAAC-OS film, the proportion of the impurity The region where the material was added is transformed, and regions with different proportions of c-axis oriented crystals are formed. It may also be possible.

[0283] In addition, the out-of-plane structure of the CAAC-OS film with InGaZnO4 crystals In the analysis by the NMR method, in addition to the peak at 2θ near 31°, a peak also appeared at 2θ near 36°. The peak at 2θ around 36° is due to the presence of c-axis orientation in part of the CAAC-OS film. The CAAC-OS film contains crystals that do not have crystalline structure. It is preferable that the peak is exhibited at 2θ of about 36° and that the peak is not exhibited at 2θ of about 36°.

[0284] The CAAC-OS film is an oxide semiconductor film with a low concentration of impurities. The oxide semiconductor film is made of an element other than the main component, such as silicon or a transition metal element. The elements such as ZnO, which have stronger bonding strength with oxygen than the metal elements constituting the oxide semiconductor film, By removing oxygen from the oxide semiconductor film, the atomic arrangement of the oxide semiconductor film is disrupted, and the crystallinity is reduced. In addition, heavy metals such as iron and nickel, argon, and carbon dioxide are Because the diameter (or molecular radius) is large, when the molecule is contained inside the oxide semiconductor film, The impurities contained in the oxide semiconductor film are likely to disturb the atomic arrangement of the oxide semiconductor film, which may result in a decrease in crystallinity. The pure material may act as a carrier trap or a carrier generation source.

[0285] The CAAC-OS film is an oxide semiconductor film with a low density of defect states. Oxygen vacancies in semiconductor films can act as carrier traps and trap hydrogen. This can become a carrier generation source.

[0286] The low impurity concentration and low defect level density (low oxygen vacancies) are called high-purity intrinsic or The term "high-purity intrinsic" refers to a substantially high-purity intrinsic oxide semiconductor. Since the film has a small number of carrier generation sources, the carrier density can be reduced. The transistor using the oxide semiconductor film has electrical characteristics (noise) such that the threshold voltage is negative. It is also called "marine.") It is rare for it to become pure or substantially pure. An intrinsic oxide semiconductor film has few carrier traps. Transistors using this film have little fluctuation in electrical characteristics and are highly reliable. Note that it takes time for the charges trapped in the carrier traps in the oxide semiconductor film to be released. The time is long and the charge may behave as if it is fixed. Therefore, a transistor using an oxide semiconductor film with a high density of defect states has unstable electrical characteristics. This may be the case.

[0287] In addition, the electrical characteristics of transistors using CAAC-OS films are improved by irradiation with visible light or ultraviolet light. There is little gender variation.

[0288] Next, a microcrystalline oxide semiconductor film will be described.

[0289] In the microcrystalline oxide semiconductor film, crystal parts can be clearly seen in the TEM image. The crystal parts contained in the microcrystalline oxide semiconductor film may have a size of 1 nm or more and 100 nm or more. In particular, the size of the particles is between 1 nm and 10 nm. Nanocrystals (nc) are microcrystals with a diameter of 1 nm or less, or 1 nm to 3 nm. The oxide semiconductor film having nc-OS (nanocrystalline O The nc-OS film is called an oxide semiconductor film. In EM observation images, the grain boundaries may not be clearly visible.

[0290] The nc-OS film is a microscopic region (e.g., a region of 1 nm to 10 nm, especially a region of 1 nm or less). The nc-OS film has a periodic atomic arrangement in the region of 3 nm or less. There is no regularity in the crystal orientation between the crystal parts, and therefore no orientation is observed throughout the film. Therefore, the nc-OS film cannot be distinguished from an amorphous oxide semiconductor film depending on the analytical method. For example, XRD, which uses X-rays with a diameter larger than that of the crystal part, is used for nc-OS films. When structural analysis is performed using the device, the crystal plane is analyzed using the out-of-plane method. In addition, the peaks shown in the figure are not detected in the nc-OS film because the probe diameter is larger than that of the crystalline part. Electron beam diffraction (also called selected area electron beam diffraction) using an electron beam (for example, 50 nm or larger) When the nc-OS film is subjected to the annealing, a halo-like diffraction pattern is observed. The probe diameter is close to or smaller than the crystal part (for example, 1 nm to 30 nm). When electron beam diffraction (also called nanobeam electron diffraction) is performed, spots are observed. In addition, when nanobeam electron diffraction is performed on the nc-OS film, a circular pattern ( In some cases, bright regions (ring-shaped) are observed. When electron beam diffraction is performed, multiple spots may be observed within the ring-shaped region.

[0291] The nc-OS film is an oxide semiconductor film with higher order than an amorphous oxide semiconductor film. Therefore, the nc-OS film has a lower density of defect states than the amorphous oxide semiconductor film. In the nc-OS film, there is no regularity in the crystal orientation between different crystal parts. The OS film has a higher density of defect states than the CAAC-OS film.

[0292] The oxide semiconductor film may be, for example, an amorphous oxide semiconductor film, a microcrystalline oxide semiconductor film, or a C The AAC-OS film may be a laminate film having two or more kinds of films.

[0293] For example, there are three methods for forming CAAC-OS.

[0294] In the first method, an oxide semiconductor film is formed at a film formation temperature of 100° C. or more and 450° C. or less. Therefore, the c-axis of the crystal part included in the oxide semiconductor film is aligned with the normal vector of the surface where the film is formed or the This is a method for forming crystals aligned in a direction parallel to the normal vector.

[0295] The second method is to form a thin oxide semiconductor film and then heat it at a temperature of 200°C to 700°C. By the heat treatment, the c-axis of the crystal part included in the oxide semiconductor film is aligned with the normal vector of the surface where the oxide semiconductor film is formed. This is a method for forming crystals aligned in a direction parallel to the normal vector of the crystal or surface.

[0296] The third method is to deposit a thin oxide semiconductor film as a first layer, and then heat the film at 200°C or higher for 700°C. Then, a second oxide semiconductor film is formed. The c-axis of the crystalline part contained in the film is parallel to the normal vector of the surface on which it is formed or the normal vector of the surface. This is a method for forming crystals aligned in a specific direction.

[0297] A transistor using CAAC-OS for an oxide semiconductor film can be irradiated with visible light or ultraviolet light. Therefore, the change in electrical characteristics due to the application of CAAC-OS to the oxide semiconductor film is small. The transistor has good reliability.

[0298] In addition, CAAC-OS uses a polycrystalline oxide semiconductor sputtering target. It is preferable to form the film by sputtering. When ions collide with the target, the crystalline regions in the sputtering target are converted from the ab plane to The particles are cleaved from the ab plane to form plate-like or pellet-like sputtered particles with a plane parallel to the ab plane. In this case, the plate-like or pellet-like sputtered particles may peel off. By reaching the deposition surface while maintaining its crystalline state, CAAC-OS can be deposited. Cut.

[0299] In addition, the following conditions are preferably applied to form a CAAC-OS film.

[0300] By reducing the amount of impurities mixed in during film formation, it is possible to prevent the crystal state from being destroyed by impurities. For example, the concentration of impurities (hydrogen, water, carbon dioxide, nitrogen, etc.) present in the film formation chamber can be In addition, the impurity concentration in the deposition gas can be reduced. A deposition gas having a temperature of −80° C. or lower, preferably −100° C. or lower is used.

[0301] In addition, by increasing the heating temperature of the surface to be film-formed (for example, the substrate heating temperature) during film formation, Specifically, the temperature of the surface on which the film is to be formed increases. The temperature is set to 100°C or higher and 740°C or lower, preferably 150°C or higher and 500°C or lower. By increasing the temperature of the surface during film formation, plate-shaped or pellet-shaped sputtering particles When it reaches the surface on which the film is to be formed, migration occurs on the surface on which the film is to be formed, resulting in sputtering. The flat surface of the particle adheres to the surface on which the film is to be formed.

[0302] In addition, by increasing the oxygen ratio in the deposition gas and optimizing the power, plasma damage during deposition can be reduced. The oxygen ratio in the film forming gas is 30% by volume or more, preferably 100% by volume or more. Expressed as volume %.

[0303] As an example of a sputtering target, an In-Ga-Zn-O compound target is used. The details are shown below.

[0304] InO X powder, GaO Y Powder and ZnO Z The powders are mixed in a specified number of moles and then pressurized. By heat treatment at a temperature between 1000℃ and 1500℃, polycrystalline In-Ga -Zn-based metal oxide target. The pressure treatment is performed while cooling (or cooling naturally). The reaction may be carried out from the start or while heating. X, Y and Z are any positive numbers. Here, the predetermined molar ratio is, for example, InO X powder, GaO Y Powder and ZnO Z powder is 2:2:1, 8:4:3, 3:1:1, 1:1:1, 4:2:3 or 3:1:2 The type of powder and the molar ratio of the powder to be mixed depend on the sputtering temperature to be prepared. You can change it as needed depending on the target.

[0305] The oxide semiconductor film may have a structure in which a plurality of oxide semiconductor films are stacked. The oxide semiconductor film is a stack of a first oxide semiconductor film and a second oxide semiconductor film. The oxide semiconductor film and the second oxide semiconductor film may be made of metal oxides having different atomic ratios. For example, the first oxide semiconductor film may be formed of an oxide containing two kinds of metals or an oxide containing three kinds of metals. The first oxide is formed on the second oxide semiconductor film by using one of the oxides containing four kinds of metals. Oxides containing two types of metals different from the semiconductor film, oxides containing three types of metals, and oxides containing four types of metals may be used.

[0306] The oxide semiconductor film may have a two-layer structure, and the constituent elements of the first oxide semiconductor film and the second oxide semiconductor film may be the same, while their atomic ratios may be different. For example, the atomic ratio of the first oxide semiconductor film may be In:Ga:Zn = 3:1:2, and the atomic ratio of the second oxide semiconductor film may be In :Ga:Zn = 1:1:1. Also, the atomic ratio of the first oxide semiconductor film may be In :Ga:Zn = 2:1:3, and the atomic ratio of the second oxide semiconductor film may be In:Ga:Zn = 1:3:2. Note that the atomic ratio of each oxide semiconductor film includes fluctuations of plus or minus 20% of the above atomic ratio as an error. :Ga:Zn = 2:1:3, and the atomic ratio of the second oxide semiconductor film may be In:Ga:Zn = 1:3:2. Note that the atomic ratio of each oxide semiconductor film includes fluctuations of plus or minus 20% of the above atomic ratio as an error. :Ga:Zn = 2:1:3, and the atomic ratio of the second oxide semiconductor film may be In:Ga:Zn =

[0307] At this time, among the first oxide semiconductor film and the second oxide semiconductor film, the atomic ratio of In and Ga in the oxide semiconductor film closer to the gate electrode ( channel side) may be In≥Ga. Also, the atomic ratio of In and Ga in the oxide semiconductor film farther from the gate electrode (back-channel side) may be In<Ga. With these laminated structures, a transistor with a high field-effect mobility can be fabricated. On the other hand, by setting the atomic ratio of In and Ga in the oxide semiconductor film closer to the gate electrode (channel side) to In<Ga and the atomic ratio of In and G a in the oxide semiconductor film on the back-channel side to In≥Ga, the variation amount of the threshold voltage due to the change over time of the transistor and the reliability test can be reduced. In and Ga in the oxide semiconductor film closer to the gate electrode (channel side) may be In<Ga, and the atomic ratio of In and G a in the oxide semiconductor film on the back-channel side may be In≥Ga, thereby reducing the variation amount of the threshold voltage due to the change over time of the transistor and the reliability test. a in the oxide semiconductor film on the back-channel side may be In≥Ga, thereby reducing the variation amount of the threshold voltage due to the change over time of the transistor and the reliability test.

[0308] The first oxide semiconductor film with an atomic ratio of In:Ga:Zn = 1:3:2 has an atomic ratio of The sputtering method was performed using an oxide target with In:Ga:Zn=1:3:2. The substrate temperature is set to room temperature, and the sputtering gas is argon or argon and oxygen. It can be formed using a mixture of In, Ga, and Zn atoms in the In:Ga:Zn=3:1:2 ratio. The second oxide semiconductor film is an oxide semiconductor film having an atomic ratio of In:Ga:Zn=3:1:2. The second oxide semiconductor film can be formed using a target in a manner similar to that for the first oxide semiconductor film.

[0309] In addition, the oxide semiconductor film has a three-layer structure, and the first oxide semiconductor film, the second oxide semiconductor film, and the third oxide semiconductor film are The oxide semiconductor film may contain the same elements but have different atomic ratios. The three-layer structure will be described with reference to FIG.

[0310] The transistor 297 illustrated in FIG. 34 includes a first oxide semiconductor film 299a, a second oxide semiconductor film 299b, and a The conductor film 299b and the third oxide semiconductor film 299c are stacked in this order from the gate insulating film 127 side. The first oxide semiconductor film 299a and the third oxide semiconductor film 299c are formed. The material used is InM1 x Zn y O z (x≧1, y>1, z>0, M1=Ga, Hf, etc.) The first oxide semiconductor film 299a and the third oxide semiconductor film 299b are formed of a material that can be expressed as follows: When Ga is contained in the material constituting the conductive film 299c, the ratio of Ga contained is high. InM1 X Zn Y O Z If X exceeds 10, powder will be generated during film formation. Note that in the transistor 297, the first oxide semiconductor film The structure other than the second oxide semiconductor film 299a, the second oxide semiconductor film 299b, and the third oxide semiconductor film 299c The structure is the same as that of the transistor described in the above embodiment (for example, the transistor described in the first embodiment). It has the same configuration as the register 103).

[0311] The material forming the second oxide semiconductor film 299b is InM2 x Zn y O z (x≧ Use materials that can be expressed as: 1, y≧x, z>0, M2=Ga, Sn, etc.

[0312] The conduction band of the first oxide semiconductor film 299a and the conduction band of the third oxide semiconductor film 299c are In comparison, the conduction band of the second oxide semiconductor film 299b is deepest from the vacuum level. Materials for the first, second, and third oxide semiconductor films are selected as appropriate to form the structure.

[0313] As described in Embodiment 1, in the oxide semiconductor film, Some silicon and carbon generate electrons, which act as carriers, and increase the carrier density. Therefore, when silicon or carbon is contained in an oxide semiconductor film, the oxide semiconductor film becomes n-type. Therefore, the silicon concentration and carbon concentration in each oxide semiconductor film are 3×10 18 / c m 3 Less than or equal to 3 x 10 17 / cm 3 In particular, the second oxide semiconductor film 2 The first oxide semiconductor film 299a and the third oxide semiconductor film 299b are formed in such a manner that a large amount of Group 14 elements are not mixed into the first oxide semiconductor film 299a and the third oxide semiconductor film 299b. The second oxide semiconductor film 299b serving as a carrier path is sandwiched between the first oxide semiconductor film 299c. That is, the first oxide semiconductor film 299a and the third oxide semiconductor film 299b are preferably disposed in the first oxide semiconductor film 299b or in the second oxide semiconductor film 299c. The oxide semiconductor film 299c is a second oxide semiconductor film containing a Group 14 element such as silicon or carbon. It can also be called a barrier film that prevents contamination of 299b.

[0314] For example, the atomic ratio of the first oxide semiconductor film 299a is In:Ga:Zn=1:3:2. The atomic ratio of the second oxide semiconductor film 299b is In:Ga:Zn=3:1:2. The atomic ratio of the oxide semiconductor film 299c in No. 3 may be In:Ga:Zn=1:1:1. Note that the atomic ratio of the third oxide semiconductor film 299c is In:Ga:Zn=1:1:1. It can be formed by sputtering using an oxide target.

[0315] Alternatively, the first oxide semiconductor film 299a may be formed of a compound semiconductor having an atomic ratio of In:Ga:Zn=1:3:2. and the second oxide semiconductor film 299b is an oxide semiconductor film having an atomic ratio of In:Ga: an oxide semiconductor film having a composition of Zn=1:1:1 or In:Ga:Zn=1:3:2; The oxide semiconductor film 299c is an oxide semiconductor having an atomic ratio of In:Ga:Zn=1:3:2. It may also have a three-layer structure with a membrane.

[0316] The first to third oxide semiconductor films 299a to 299c contain the same elements. Therefore, the second oxide semiconductor film 299b has a thin film at the interface with the first oxide semiconductor film 299a. In detail, the defect level (trap level) is than the defect states at the interface between the gate insulating film 127 and the first oxide semiconductor film 299a. Therefore, by stacking oxide semiconductor films as described above, This can reduce the amount of variation in threshold voltage due to deterioration over time or due to reliability testing.

[0317] In addition, the conduction band of the first oxide semiconductor film 299a and the conduction band of the third oxide semiconductor film 299c The conduction band of the second oxide semiconductor film 299b is the deepest from the vacuum level compared to the conduction band. The materials of the first, second, and third oxide semiconductor films are appropriately selected so as to form a well structure. By doing so, it is possible to increase the field effect mobility of the transistor and This can reduce the amount of variation in threshold voltage due to deterioration over time of the transistor or due to reliability testing.

[0318] In addition, the first to third oxide semiconductor films 299a to 299c are formed of crystalline oxide semiconductor films. Different oxide semiconductors may be used. For example, a single-crystal oxide semiconductor, a polycrystalline oxide semiconductor, etc. A conductor, an amorphous oxide semiconductor, and a CAAC-OS may be combined as appropriate. In addition, any one of the first to third oxide semiconductor films 299a to 299c When an amorphous oxide semiconductor is used, the internal stress and external stress of the oxide semiconductor film are alleviated. , the variation in transistor characteristics is reduced, and the deterioration of transistors over time and reliability tests are also This can reduce the amount of variation in threshold voltage.

[0319] At least the second oxide semiconductor film 299b which can be a channel formation region is formed of CAA The oxide semiconductor film on the back channel side is preferably C-OS. In this embodiment, the third oxide semiconductor film 299c is amorphous or CAAC-OS. By adopting such a structure, it is possible to prevent deterioration of the transistor over time and the deterioration of the transistor due to reliability tests. The amount of variation in threshold voltage can be reduced.

[0320] Note that the structure described in this embodiment mode may be appropriately combined with structures described in other embodiments. It can be used.

[0321] (Embodiment 5) A semiconductor device having a display function using the transistor and the capacitor described as an example in the above embodiment A semiconductor device (also called a display device) can be manufactured. A part or the whole of the operating circuit is formed on the same substrate as the pixel section to form a system on panel. In this embodiment, the transistors exemplified in the above embodiments can be used. Examples of the display device will be described with reference to FIGS. 35 to 37. FIG. 36(B) is a cross-sectional view showing the cross-sectional structure of the portion indicated by the dashed line MN in FIG. 35(B). 36, only a part of the structure of the pixel section is shown.

[0322] In FIG. 35(A), a pixel portion 902 provided on a first substrate 901 is surrounded by a A sealant 905 is provided, and the substrate is sealed with a second substrate 906. ) is different from the region surrounded by the sealing material 905 on the first substrate 901. A signal line driver formed of a single crystal semiconductor or a polycrystalline semiconductor on a separately prepared substrate is formed in the region where the signal line driver is formed. A signal line driver circuit 903 and a scanning line driver circuit 904 are mounted on the display panel. 3. Various signals and potentials given to the scanning line driver circuit 904 or the pixel portion 902 are transmitted through the FPC (Flexible printed circuit) 918a, FPC 918b is being supplied.

[0323] In FIG. 35(B) and FIG. 35(C), a pixel portion 90 provided on a first substrate 901 A sealant 905 is provided so as to surround the scanning line driver circuit 904. A second substrate 906 is provided on the pixel portion 902 and the scanning line driver circuit 904. The pixel portion 902 and the scanning line driver circuit 904 are formed by the first substrate 901 and the sealing material 905. The display element is sealed with the second substrate 906. In (C), the region surrounded by the sealing material 905 on the first substrate 901 is In different regions, signals formed with single crystal semiconductors or polycrystalline semiconductors on separately prepared substrates are 35(B) and 35(C), the signal line Various signals and voltages are applied to the driver circuit 903, the scanning line driver circuit 904, or the pixel portion 902. The position is supplied by FPC918.

[0324] In addition, in FIG. 35(B) and FIG. 35(C), a signal line driver circuit 903 is separately formed. 9, an example in which the scanning line is mounted on the first substrate 901 is shown, but the present invention is not limited to this configuration. The driver circuit may be formed separately and mounted, or may be mounted as part of the signal line driver circuit or the scanning line driver circuit. Only a part of it may be formed separately and mounted.

[0325] The method of connecting the separately formed drive circuit is not particularly limited, and may be a COG (C Hip On Glass method, wire bonding method, or TAB (Tape On Glass) method Automated Bonding (ABA) method can be used. This is an example in which a signal line driver circuit 903 and a scanning line driver circuit 904 are implemented by the COG method. FIG. 35(B) shows an example in which a signal line driver circuit 903 is mounted by the COG method. C) is an example in which the signal line driver circuit 903 is mounted by the TAB method.

[0326] The display device includes a panel in which a display element is sealed, and a controller for the panel. This includes modules in which ICs, etc., including lasers, are mounted.

[0327] In this specification, the term "display device" refers to an image display device, a display device, or an optical device. Also refers to a source (including lighting equipment) to which a connector, such as FPC or TCP, is attached. a module with a printed wiring board at the end of the TCP, or a display element All modules with ICs (integrated circuits) directly mounted on the chip using the COG method are included in the display device. This shall be done.

[0328] In addition, the pixel portion and the scanning line driver circuit provided on the first substrate have a plurality of transistors. The transistor described in the above embodiment can be applied to this.

[0329] Examples of display elements provided in the display device include liquid crystal elements (also called liquid crystal display elements), light-emitting elements, and the like. A light-emitting element (also called a light-emitting display element) can be used. This category includes elements whose brightness is controlled by the light source, specifically inorganic EL (Electroluminescent) Luminescence elements, organic EL elements, etc. Also, electronic ink, etc. A display medium whose contrast changes due to electrical effects can also be used. 1 shows an example of a liquid crystal display device using a liquid crystal element as a display element.

[0330] The liquid crystal display device shown in Figure 36(A) is a vertical electric field type liquid crystal display device. has a connection terminal electrode 915 and a terminal electrode 916, and the connection terminal electrode 915 and the terminal The electrode 916 is electrically connected to a terminal of the FPC 918 via an anisotropic conductive material 919. It is being done.

[0331] The connection terminal electrode 915 is formed from the same conductive film as the first electrode 930, and the terminal electrode 916 are formed of the same conductive film as the source and drain electrodes of the transistors 910 and 911. are.

[0332] In addition, a pixel portion 902 and a scanning line driver circuit 904 provided on a first substrate 901 are 36(A) and 36(B), the pixel portion 902 includes a plurality of transistors. 9, a transistor 910 included in the scanning line driver circuit 904 and a transistor 911 included in the scanning line driver circuit 904 are shown. The insulating layer shown in Embodiment 1 is formed on the transistor 910 and the transistor 911. An insulating film 924 corresponding to the film 129, the insulating film 131, and the insulating film 132 is provided. Note that the insulating film 923 functions as a base film.

[0333] In this embodiment, the transistors 910 and 911 are the same as those in the above embodiment. In addition, the oxide semiconductor film 927 The capacitor 926 is formed using the insulating film 924 and the first electrode 930. The compound semiconductor film 927 is connected to a capacitance line 929 via an electrode film 928. The source and drain electrodes of the transistors 910 and 911 are the same conductive type. The capacitor line 929 is formed from a film. The capacitor 926 is formed from the same conductive film as the electrode. Although the capacitor element shown in FIG. 1 is illustrated, the capacitor element shown in other embodiments may be used as appropriate. can be done.

[0334] In addition, the insulating film 924 is formed on the insulating film 924 by oxidizing the transistor 911 included in the scan line driver circuit. 9 shows an example in which a conductive film 917 is provided at a position overlapping with a channel forming region of a compound semiconductor film. That is, the transistor 911 is the dual gate transistor described in the first embodiment. Although not shown, the conductive film 917 is electrically connected to a capacitor line 929. In this embodiment mode, the conductive film 917 is formed using the same conductive film as the first electrode 930. By doing so, it is possible to omit the configuration for controlling the potential of the conductive film 917. By providing the conductive film 917 in a position overlapping with the channel formation region of the oxide semiconductor film, Further reducing the amount of variation in the threshold voltage of the transistor 911 before and after reliability testing. In addition, the operating speed of the transistor 911 can be increased, and the operating speed of the driver circuit can be increased. In addition, the potential of the conductive film 917 can be adjusted to the gate The conductive film 917 may be the same as or different from the second gate electrode (battery). The conductive film 917 and the transistor 91 can also function as a gate electrode. The potential difference between the source electrode and the gate electrode may be 0 V. This allows for both an increase in capacity and a reduction in power consumption.

[0335] The conductive film 917 also has a function of blocking an external electric field. (circuit parts including transistors) The shielding function of the conductive film 917 prevents the influence of external electric fields such as static electricity. This can suppress fluctuations in the electrical characteristics of the transistor. In FIG. 36, the threshold voltage of the scanning line driving circuit can be controlled. However, the transistors included in the signal line driver circuit are also shown as transistors. Similar to the transistor 911, the channel formation region of the oxide semiconductor film and the insulating film 924 are A conductive film may be provided at the overlapping position.

[0336] The transistor 910 provided in the pixel portion 902 is electrically connected to a display element. The display element is not particularly limited as long as it can display, and various display elements can be used. It can be used.

[0337] The liquid crystal element 913, which is a display element, is made up of a first electrode 930, a second electrode 931, and a liquid crystal 9 The liquid crystal 908 is sandwiched between insulating films 932, 933, and 934, which function as alignment films. The second electrode 931 is provided on the second substrate 906 side. The first electrode 930 and the second electrode 931 are configured to overlap with each other via the liquid crystal 908. For the liquid crystal element 913, reference can be made to the liquid crystal element 108 described in Embodiment 1. The first electrode 930 corresponds to the pixel electrode 121 described in the first embodiment, and the second electrode 931 corresponds to the counter electrode 154 described in the first embodiment, and the liquid crystal 908 corresponds to the counter electrode 154 described in the first embodiment. The insulating film 932 corresponds to the alignment film 158 described in the first embodiment. The insulating film 933 corresponds to the alignment film 156 described in Embodiment 1.

[0338] The first electrode and the second electrode (pixel electrode, common electrode, counter electrode) that apply a voltage to the display element In the case of a reflective electrode, the direction of the light to be extracted, the location of the electrodes, and the pattern of the electrodes are all important factors. The transparency or reflectivity can be selected depending on the structure of the film.

[0339] The first electrode 930 and the second electrode 931 are the same as the pixel electrode 121 and the corresponding electrode shown in Embodiment 1. The same material as that of the counter electrode 154 can be used as appropriate.

[0340] The spacers 935 are columnar spacers obtained by selectively etching the insulating film. The distance between the first electrode 930 and the second electrode 931 (cell gap) is controlled by the It is to be noted that a spherical spacer may also be used.

[0341] The first substrate 901 and the second substrate 906 are fixed by a sealing material 925. The cooling material 925 may be an organic resin such as a thermosetting resin or a photosetting resin. The sealing material 925 is in contact with the insulating film 924. The sealing material 925 is Equivalent to material 905.

[0342] In addition, in liquid crystal display devices, black matrices (light-shielding films), polarizing members, and phase difference members Optical members (optical substrates) such as anti-reflection members are provided as appropriate. Circularly polarized light produced by a retardation substrate may also be used. Any light source device may be used.

[0343] In addition, since transistors are easily damaged by static electricity, etc., a protective circuit for protecting the drive circuit is It is preferable to provide a path. The protection circuit is preferably constructed using a non-linear element.

[0344] Next, a liquid crystal display device of the lateral electric field type will be described with reference to FIG. B) is an example of a horizontal electric field method, FFS (Fringe Field Switching) ng) mode liquid crystal display device. The structure will be explained below.

[0345] In the liquid crystal display device shown in FIG. 36(B), the connection terminal electrode 915 is connected to the first electrode 940. The terminal electrode 916 is formed from the same conductive film as the source electrodes of the transistors 910 and 911. The gate electrode is formed from the same conductive film as the gate and drain electrodes.

[0346] The liquid crystal element 943 has a first electrode 940 and a second electrode 941 formed on the insulating film 924. The liquid crystal element 943 includes the liquid crystal element 108 described in Embodiment 1. The first electrode 940 can be formed by the first electrode shown in FIG. The materials shown in 930 can be used appropriately. The first electrode 940 has a planar shape as follows: The second electrode 941 functions as a common electrode, and in the embodiment The first electrode 940 and the oxide semiconductor film 119 can be formed in a similar manner to the oxide semiconductor film 119 in Embodiment 1. An insulating film 924 is provided between the second electrodes 941. In the device, the capacitive element is a pair of electrodes, a first electrode 940 and a second electrode, and a dielectric The insulating film 924 is a protective film.

[0347] The second electrode 941 is connected to a capacitor line 946 through a conductive film 945. 945 is the same as the source and drain electrodes of the transistor 910 and the transistor 911. The capacitor line 946 is formed from the same conductive film as the transistor 910 and the transistor 911. It is formed from the same conductive film as the gate electrode. Although the description has been given using the capacitance element shown in the first embodiment, capacitance elements shown in other embodiments may be used as appropriate. You can be there.

[0348] 37, in the liquid crystal display device shown in FIG. 36(A), A common connection portion (pad portion) for electrically connecting with the second electrode 931 is provided on the first substrate 90. An example of forming on 1 is shown below.

[0349] The common connection portion overlaps with the sealant for bonding the first substrate 901 and the second substrate 906. and electrically connected to the second electrode 931 via conductive particles contained in the sealing material. Or, connect the common connection part to a place that does not overlap with the sealing material (excluding the pixel part). A paste containing conductive particles is provided separately from the sealing material so as to overlap the common connection portion. The second electrode 931 may be electrically connected to the first electrode 931.

[0350] FIG. 37(A) is a cross-sectional view of the common connection portion, and corresponds to IJ in the top view shown in FIG. 37(B). Correct.

[0351] The common potential line 975 is provided on the gate insulating film 922 and is connected to the transistor 9 shown in FIG. 10. The source electrode 971 or the drain electrode 973 is fabricated using the same material and in the same process.

[0352] The common potential line 975 is covered with an insulating film 924. 5. The openings are for connecting the source and drain electrodes of the transistor 910. A contact hole connecting one of the drain electrode 971 or the drain electrode 973 to the first electrode 930 is provided. It is made using the same process as the coil.

[0353] Furthermore, the common potential line 975 and the common electrode 977 are connected at the opening. is provided on the insulating film 924 and is the same as the connection terminal electrode 915 and the first electrode 930 of the pixel portion. It is made from the same materials and using the same process.

[0354] In this way, the common connection portion is formed by the same manufacturing process as the switching element of the pixel portion 902. It can be manufactured.

[0355] The common electrode 977 is an electrode that comes into contact with the conductive particles contained in the sealing material, and is connected to the second substrate. Electrical connection is made with the second electrode 931 of 906 .

[0356] 37(C), the common potential line 985 is connected to the gate of the transistor 910. The electrode may be made of the same material and in the same process as the electrode.

[0357] In the common connection portion shown in FIG. 37(C), the common potential line 985 is connected to the gate insulating film 922 and The gate insulating film 922 and the insulating film 924 are disposed below the common potential line The openings are located at positions overlapping with the source electrode 985 of the transistor 910. A contact hole connecting one of the drain electrode 971 or drain electrode 973 to the first electrode 930 After etching the insulating film 924 in the same process, the gate insulating film 922 is selectively etched. It is formed by etching.

[0358] Furthermore, the common potential line 985 and the common electrode 987 are connected at the opening. is provided on the insulating film 924 and is the same as the connection terminal electrode 915 and the first electrode 930 of the pixel portion. It is made from the same materials and using the same process.

[0359] As described above, in a semiconductor device having a driver circuit, a transistor included in the driver circuit a back gate electrode of a dual gate transistor; By electrically connecting the capacitor element to the capacitor line, power consumption is reduced. The operating speed of the driving circuit can be increased while maintaining the high image quality, thereby providing a semiconductor device with excellent display quality. It is possible.

[0360] In addition, a semiconductor film (specifically, an oxide semiconductor film) of a transistor is used as one electrode of the capacitor. By using a semiconductor film formed in the same process as the charge carrier film, the aperture ratio can be increased while It is possible to manufacture a semiconductor device having a capacitor element with an increased capacitance. By doing so, a semiconductor device with excellent display quality can be obtained.

[0361] Furthermore, oxygen vacancies in a semiconductor film (specifically, an oxide semiconductor film) of a transistor are reduced, Since impurities such as hydrogen and nitrogen are reduced, the semiconductor device according to one embodiment of the present invention can be The semiconductor device has excellent electrical characteristics.

[0362] Note that the structure described in this embodiment mode may be appropriately combined with structures described in other embodiments. It can be used.

[0363] (Sixth embodiment) The semiconductor device according to one embodiment of the present invention can be applied to various electronic devices (including gaming machines). The electronic device can be a television device (television or television receiver) ), computer monitors, digital cameras, digital video cameras, Digital photo frames, mobile phones, portable game consoles, personal digital assistants, sound reproduction devices, These electronic devices include gaming machines (pachinko machines, slot machines, etc.) and game cabinets. An example is shown in Figure 38.

[0364] FIG. 38(A) shows a table 9000 having a display section. A display unit 9003 is built into the housing 9001, and images are displayed on the display unit 9003. It is possible to support the housing 9001 with four legs 9002. The housing 9001 also has a power cord 9005 for supplying power.

[0365] The semiconductor device described in any of the above embodiments can be used for the display portion 9003. Therefore, the display quality of the display portion 9003 can be improved.

[0366] The display unit 9003 has a touch input function. By touching the display button 9004 displayed on the screen with a finger or the like, the screen can be operated or information can be input. It can also communicate with other home appliances or control them, improving the image quality. It may also be used as a control device to control other home appliances by surface manipulation. If a semiconductor device having a sensor function is used, the display portion 9003 can have a touch input function. It is possible.

[0367] In addition, the screen of the display unit 9003 can be tilted relative to the floor by a hinge provided in the housing 9001. It can also be placed vertically and used as a television set. When a large screen television is installed, the free space becomes narrow, but the table If the display unit is built into the device, the space in the room can be used more effectively.

[0368] FIG. 38(B) shows a television device 9100. Television device 9100 The display unit 9103 is incorporated in the housing 9101, and the display unit 9103 displays images. In this example, the housing 9101 is supported by a stand 9105. The figure shows the configuration.

[0369] The television device 9100 can be operated using an operation switch provided on the housing 9101 or a separate remote control. This can be done by using the remote control operation device 9110. The channel and volume can be controlled by the -9109, and the information displayed on the display 9103 In addition, the remote control unit 9110 can be used to control the video. A display unit 9107 for displaying information output from the device 9110 may be provided.

[0370] A television device 9100 shown in FIG. 38(B) includes a receiver, a modem, and the like. The television device 9100 can receive general television broadcasts using a receiver. Furthermore, by connecting to a wired or wireless communication network via a modem, One-way (sender to receiver) or two-way (between sender and receiver, or between receivers) It is also possible to carry out information communication.

[0371] The semiconductor device described in any of the above embodiments can be used for the display portions 9103 and 9107. Therefore, the display quality of the television device can be improved.

[0372] FIG. 38(C) shows a computer, which includes a main body 9201, a housing 9202, a display portion 9203, Keyboard 9204, external connection port 9205, pointing device 9206, etc. include.

[0373] The semiconductor device described in any of the above embodiments can be used for the display portion 9203. Therefore, the display quality of the computer can be improved.

[0374] Figures 39(A) and 39(B) show a foldable tablet terminal. ) is in an open state, and the tablet terminal includes a housing 9630, a display unit 9631a, a display part 9631b, a display mode changeover switch 9034, a power switch 9035, a power saving mode It has a mode changeover switch 9036, a fastener 9033, and an operation switch 9038.

[0375] The semiconductor device described in any of the above embodiments includes a display portion 9631a and a display portion 9631b. Therefore, it is possible to improve the display quality of tablet devices. Cut.

[0376] A part of the display portion 9631a can be used as a touch panel area 9632a. By touching the operation keys 9638, data can be input. In 31a, for example, half of the area has a display function only, and the other half Although the display area 96 has a touch panel function, the display area 96 is not limited to this configuration. The entire area of ​​the display unit 9 may have a touch panel function. The entire surface of 631a is displayed as a keyboard button to serve as a touch panel, and the display part 9631b is displayed. It can be used as a display screen.

[0377] In addition, in the display unit 9631b, as in the display unit 9631a, The area can be used as a touch panel area 9632b. Touch the area where the display switch button 9639 is displayed with your finger or a stylus. This allows keyboard buttons to be displayed on the display portion 9631b.

[0378] In addition, the touch panel area 9632a and the touch panel area 9632b are simultaneously You can also use touch input.

[0379] A display mode changeover switch 9034 is used to change the display orientation, such as portrait or landscape. You can switch between black and white and color display. The Switch 9036 detects external light during use using a light sensor built into the tablet device. The tablet device can optimize the display brightness according to the amount of light in the room. In addition to sensors, other detection devices such as gyros and acceleration sensors that detect tilt are also included. It may be built-in.

[0380] FIG. 39(A) shows an example in which the display areas of the display portions 9631b and 9631a are the same. However, there is no particular limitation, and one size may be different from the other size. The display quality may also differ. For example, one display panel may be able to display a higher resolution image than the other. It may also be used as a rule.

[0381] FIG. 39(B) shows the tablet terminal in a closed state, and the tablet terminal includes a housing 9630 and a solar cell 9631. 39B, the charge / discharge control circuit 96 As an example of 34, a configuration having a battery 9635 and a DC-DC converter 9636 is shown. This shows that.

[0382] In addition, since the tablet device can be folded in half, when not in use, the case 9630 is closed. Therefore, the display portions 9631a and 9631b can be protected. This makes it possible to provide a tablet device that is highly durable and reliable even for long-term use.

[0383] In addition, the tablet terminals shown in Figures 39(A) and 39(B) can be used in various Functions that display information (still images, videos, text images, etc.), calendars, dates, or times The function to display information on the display unit, and the function to input or edit the information displayed on the display unit. It has input functions, functions to control processing using various software (programs), etc. It is possible.

[0384] The solar cell 9633 attached to the surface of the tablet terminal supplies power to the touch panel. The solar cell 9633 can be supplied to a display unit, a video signal processor, or the like. The battery 9635 can be efficiently charged by providing a battery charger on one or both sides of the housing 9630. The battery 9635 is preferably a lithium battery. The use of a lithium-ion battery has the advantage of being able to reduce the size.

[0385] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 39(B) will be described with reference to FIG. A block diagram is shown in Fig. 39(C) and will be explained. 635, DC-DC converter 9636, converter 9637, switches SW1 to SW3 , the display unit 9631, the battery 9635, the DC-DC converter 963 6. The converter 9637 and the switches SW1 to SW3 are configured to perform the charge / discharge control shown in FIG. 39(B). This corresponds to the circuit 9634.

[0386] First, an example of operation when power is generated by the solar cell 9633 using external light will be described. The power generated by the solar cell 9633 becomes the voltage for charging the battery 9635. The voltage is increased or decreased by the DC-DC converter 9636. When power is used from the solar cell 9633, switch SW1 is turned on and the The inverter 9637 increases or decreases the voltage to the voltage required for the display unit 9631. When not displaying on the display unit 9631, turn SW1 off and SW2 on. The configuration may be such that the battery 9635 is charged.

[0387] The solar cell 9633 is shown as an example of a power generating means, but is not particularly limited thereto. , by other power generation means such as piezoelectric elements and thermoelectric conversion elements (Peltier elements) For example, the battery 9635 may be charged wirelessly (contactlessly). It can be combined with a non-contact power transmission module that transmits and receives power and charges, or other charging methods. This may also be configured as follows.

[0388] Note that the structure described in this embodiment mode may be appropriately combined with structures described in other embodiments. It can be used. [Example]

[0389] In this example, the resistance of the oxide semiconductor film and the multilayer film was measured using FIGS. 40 and 41. I will explain.

[0390] First, the structure of the sample will be explained with reference to FIG.

[0391] FIG. 40A is a top view of Samples 1 to 4. The cross-sectional views of Samples 1 to 4 are shown in Figure 40(B), (C), and (D). The cross-sectional view of Sample 1 is shown in Figure 40( The cross-sectional view of sample 2 is shown in Fig. 40(C), and the cross-sectional views of samples 3 and 4 are shown in Fig. 40(D). , respectively.

[0392] In the sample 1, an insulating film 1903 is formed on a glass substrate 1901, and an insulating film 1903 is formed on the insulating film 1903. An insulating film 1904 is formed, and an oxide semiconductor film 1905 is formed over the insulating film 1904. In addition, both ends of the oxide semiconductor film 1905 are covered with conductive films 1907 and 1909 which function as electrodes. The oxide semiconductor film 1905 and the conductive films 1907 and 1909 are covered with insulating films 1910 and 1911. The insulating films 1910 and 1911 are provided with openings 1913 and 1915. The conductive films 1907 and 1909 are exposed in the openings 1913 and 1915, respectively. It is being released.

[0393] In the sample 2, an insulating film 1903 is formed on a glass substrate 1901, and an insulating film 1903 is formed on the insulating film 1903. An insulating film 1904 is formed, and an oxide semiconductor film 1905 is formed over the insulating film 1904. In addition, both ends of the oxide semiconductor film 1905 are covered with conductive films 1907 and 1909 which function as electrodes. The oxide semiconductor film 1905 and the conductive films 1907 and 1909 are covered with an insulating film 1911. The insulating film 1911 has openings 1917 and 1919. At the opening, the conductive films 1907 and 1909 are exposed.

[0394] In the samples 3 and 4, an insulating film 1903 is formed on a glass substrate 1901, and an insulating film 19 An insulating film 1904 is formed on the insulating film 1903, and a multilayer film 1906 is formed on the insulating film 1904. In addition, both ends of the multilayer film 1906 are covered with conductive films 1907 and 1909 that function as electrodes. The insulating film 1911 covers the conductive film 1906 and the conductive films 1907 and 1909. 11 is provided with openings 1917 and 1919, and in the openings, The conductive films 1907 and 1909 are exposed.

[0395] In this way, Samples 1 to 4 are obtained by forming a semiconductor layer on the oxide semiconductor film 1905 or the multilayer film 1906. The structure of the insulating film in contact with the oxide semiconductor film 1905 and the insulating film 1910 is different. In Sample 2, the oxide semiconductor film 1905 and the insulating film 1911 are in contact with each other. In Sample 3, In Sample 4, the multilayer film 1906 and the insulating film 1911 are in contact with each other.

[0396] Next, the method for preparing each sample will be described.

[0397] First, the method for preparing Sample 1 will be described.

[0398] On a glass substrate 1901, an insulating film 1903 was formed by plasma CVD to a thickness of 400 A silicon nitride film with a thickness of nm was deposited.

[0399] Next, on the insulating film 1903, an insulating film 1904 is formed by plasma CVD to a thickness of 50 A silicon oxynitride film with a thickness of nm was formed.

[0400] Next, a metal oxide target ( In:Ga:Zn=1:1:1) and a 35 nm thick IGZ was deposited by sputtering. Then, an O film was formed. Then, etching was performed using a mask formed by photolithography. An oxide semiconductor film 1905 was formed by performing etching treatment.

[0401] Next, a thick film was formed on the insulating film 1904 and the oxide semiconductor film 1905 by a sputtering method. A 50 nm thick tungsten film, a 400 nm thick aluminum film, and a 100 nm thick tungsten film were After laminating the titanium films in order, etching is performed using a mask formed by photolithography. A conductive film 1907 and a conductive film 1909 were formed by performing a coating treatment.

[0402] Next, the insulating film 1904, the oxide semiconductor film 1905, the conductive film 1907, and the conductive film 190 On the substrate 9, a silicon oxynitride film having a thickness of 450 nm is formed as an insulating film 1910 by a plasma CVD method. After forming the film, it was heat-treated for 1 hour in a mixed atmosphere of nitrogen and oxygen at 350°C. .

[0403] Next, on the insulating film 1910, an insulating film 1911 is formed by plasma CVD to a thickness of 50 A silicon nitride film with a thickness of nm was deposited.

[0404] Next, after providing a mask formed by a photolithography process on the insulating film 1911, , an etching process is performed to form openings 1913 and 1914 in the insulating film 1910 and the insulating film 1911. 15 was formed.

[0405] Sample 1 was prepared by the above steps.

[0406] Next, a method for fabricating Sample 2 will be described.

[0407] The insulating film 1904, the oxide semiconductor film 1905, the conductive film 1907, and the conductive film 19 in Sample 1 On the 09, a 450 nm thick oxide nitride silicon film was formed as an insulating film 1910 by plasma CVD. After the silicon film was formed, it was heat-treated for 1 hour in a mixed atmosphere of nitrogen and oxygen at 350°C. After that, the insulating film 1910 was removed.

[0408] Next, the insulating film 1904, the oxide semiconductor film 1905, the conductive film 1907, and the conductive film 190 9, as an insulating film 1911, a silicon nitride film having a thickness of 50 nm is formed by a plasma CVD method. A film was formed.

[0409] Next, after providing a mask formed by a photolithography process on the insulating film 1911, Then, an etching process was performed to form openings 1917 and 1919 in the insulating film 1911 .

[0410] Sample 2 was prepared by the above steps.

[0411] Next, a method for preparing Sample 3 will be described.

[0412] In Sample 3, a multilayer film 1906 was used instead of the oxide semiconductor film 1905 of Sample 2. The layer film 1906 is formed by depositing a metal oxide target (In:Ga:Zn =1:3:2), a 10 nm thick IGZO film was formed by sputtering, followed by A metal oxide target (In:Ga:Zn=1:1:1) was used for sputtering. A 10 nm thick IGZO film was deposited by the ion beam, followed by a metal oxide target (In:Ga: Zn=1:3:2) and a 10 nm thick IGZO film was formed by sputtering. After that, an etching process was carried out using a mask formed by a photolithography process. Thus, a multilayer film 1906 was formed.

[0413] Sample 3 was prepared by the above steps.

[0414] Next, a method for preparing Sample 4 will be described.

[0415] In Sample 4, a multilayer film 1906 was used instead of the oxide semiconductor film 1905 of Sample 2. The layer film 1906 is formed by depositing a metal oxide target (In:Ga:Zn =1:3:2), a 20 nm thick IGZO film was formed by sputtering, followed by A metal oxide target (In:Ga:Zn=1:1:1) was used for sputtering. A 15 nm thick IGZO film was deposited by the ion beam, followed by a metal oxide target (In:Ga: Zn=1:3:2) and a 10 nm thick IGZO film was formed by sputtering. After that, an etching process was carried out using a mask formed by a photolithography process. Thus, a multilayer film 1906 was formed.

[0416] Sample 4 was prepared by the above steps.

[0417] Next, the oxide semiconductor film 1905 and the multilayer film 1906 provided in Samples 1 to 4 were The sheet resistance was measured. The sheet resistance of the oxide semiconductor film 1905 was measured by contacting the oxide semiconductor film 1905 with a solder paste. In the example shown in FIG. 4, a probe is brought into contact with the openings 1917 and 1919, and an oxide semiconductor The sheet resistance of the film 1905 and the multilayer film 1906 was measured. In the compound semiconductor film 1905 and the multilayer film 1906, the conductive film 1907 and the conductive film 190 The width of the opposing conductive film 1907 and conductive film 1909 is 1 mm, and the distance between the conductive film 1907 and conductive film 1909 is 10 μm. In Samples 1 to 4, the conductive film 1907 was set to a ground potential, and the conductive film 1909 A voltage of 1 V was applied to the

[0418] The sheet resistances of Samples 1 to 4 are shown in FIG.

[0419] The sheet resistance of sample 1 is approximately 1×10 11 The sheet resistance of sample 2 was Ω / sq. The sheet resistance of sample 3 was approximately 4410 Ω / sq. The sheet resistance of Sample 4 was about 2930 Ω / sq.

[0420] In this way, the oxide semiconductor film 1905 and the insulating film in contact with the multilayer film 1906 are different. Therefore, the oxide semiconductor film 1905 and the multilayer film 1906 have different sheet resistances.

[0421] When the sheet resistances of the above-described Samples 1 to 4 are converted into resistivities, Sample 1 has a resistivity of 3 .9×10 5 Ωcm, sample 2 is 9.3×10 -3 Ωcm, sample 3 is 1.3×10 -2 Ωcm, sample 4 is 1.3×10 -2 It was Ωcm.

[0422] Sample 1 is a silicon oxynitride film that is in contact with an oxide semiconductor film 1905 and is used as an insulating film 1910. A silicon nitride film is formed on the insulating film 1911. On the other hand, Samples 2 to 4 show that the oxide semiconductor film 1905 and the multilayer film 1906 are A silicon nitride film used as an insulating film 1911 is formed in contact with the oxide. The nitride semiconductor film 1905 and the multilayer film 1906 are made of silicon nitride, which is used as an insulating film 1911. When the oxide semiconductor film 1905 and the multilayer film 1906 are provided in contact with each other, defects, typically In this case, oxygen vacancies are formed, and hydrogen contained in the silicon nitride film is absorbed into the oxide semiconductor film 1. The oxide semiconductor film 1905 and the multilayer film 1906 are then transferred or diffused. 05 and the conductivity of the multilayer film 1906 is improved.

[0423] For example, when an oxide semiconductor film is used for a channel formation region of a transistor, It is preferable that a silicon oxynitride film be provided in contact with the oxide semiconductor film so as to cover the insulating film. As a light-transmitting conductive film used for an electrode of a quantum well, an oxide film as shown in Samples 2 to 4 is used. It is preferable to provide a silicon nitride film in contact with the nitride semiconductor film or multilayer film. By using this structure, an oxide semiconductor film used in a channel formation region of a transistor can be formed. The oxide semiconductor film or multilayer film used for the electrode of the capacitor element is fabricated in the same process. The resistivity of the oxide semiconductor film and the multilayer film can be changed even when the oxide semiconductor film and the multilayer film are fabricated.

[0424] Next, the sheet resistance of Samples 2 and 3 stored in a high-temperature, high-humidity environment was investigated. The conditions for each sample used here are explained below. In some cases, conditions used were different from those of Sample 2 and Sample 3. Samples with the same structure as Sample 3 but different preparation conditions are designated Sample 2a and Sample 3a, respectively. do.

[0425] First, a method for preparing the sample 2a will be described.

[0426] An insulating film 1903 and an insulating film 1904 were formed on a glass substrate 1901 .

[0427] A metal oxide target (In: Ga:Zn=1:1:1) and a 35 nm thick IGZO film was formed by sputtering. After that, etching was performed using a mask formed by a photolithography process. After the treatment, heat treatment is performed at 350° C. or 450° C. to form an oxide semiconductor film 1905. Successful.

[0428] A 50 nm thick oxide semiconductor film was formed over the insulating film 1904 and the oxide semiconductor film 1905 by a sputtering method. After stacking a 400 nm thick titanium film and a 400 nm thick copper film in order, a photolithography process was carried out. The conductive film 1907 and the conductive film 1909 are then subjected to etching treatment using a mask formed from the above. was formed.

[0429] Next, the insulating film 1904, the oxide semiconductor film 1905, the conductive film 1907, and the conductive film 190 On the substrate 9, a silicon oxynitride film having a thickness of 450 nm is formed as an insulating film 1910 by a plasma CVD method. After forming the film, it was heat-treated for 1 hour in a mixed atmosphere of nitrogen and oxygen at 350°C. .

[0430] Next, the insulating film 1904, the oxide semiconductor film 1905, the conductive film 1907, and the conductive film 190 9, as an insulating film 1911, a silicon nitride film having a thickness of 50 nm is formed by a plasma CVD method. The silicon nitride film was formed at a temperature of 220°C or 350°C.

[0431] Next, after providing a mask formed by a photolithography process on the insulating film 1911, , an etching process is performed to form openings 1917 and 1918 in the insulating film 1910 and the insulating film 1911. Formed 19.

[0432] Sample 2a was fabricated through the above steps.

[0433] Next, a method for producing the sample 3a will be described.

[0434] In Sample 3a, a multilayer film 1906 was used instead of the oxide semiconductor film 1905 of Sample 2a. The multilayer film 1906 is formed by depositing a metal oxide target (In:Ga: Zn=1:1:1) and a 10 nm thick IGZO film was formed by sputtering. Then, a metal oxide target (In:Ga:Zn=1:3:2) was used for sputtering. A 10 nm thick IGZO film was then formed by the photolithography process. After etching using the mask formed by the above method, the wafer was heated at 350°C or 450°C. The multilayer film 1906 was formed by the above process.

[0435] Sample 3a was fabricated through the above steps.

[0436] Next, the oxide semiconductor film 1905 and the multilayer film 190 provided in Sample 2a and Sample 3a were The sheet resistance of the sample 2a and the sample 3a was measured. A probe is brought into contact with the portion 1919, and the oxide semiconductor film 1905 and the multilayer film 1906 are sealed. The oxide semiconductor film 1905 and the multilayer film 1906 of Sample 2a and Sample 3a were measured. In 1906, the width of the conductive film 1907 and the conductive film 1909 facing each other is 1.5 mm, The distance between the film 1907 and the conductive film 1909 was set to 10 μm. In a, the conductive film 1907 was set to the ground potential, and 1 V was applied to the conductive film 1909. Samples 2a and 3a were stored in an atmosphere of 60°C and 95% humidity for 60 hours and 13 hours. After storing for 0 hours, the sheet resistance of each sample was measured.

[0437] The sheet resistance values ​​of Sample 2a and Sample 3a are shown in Figure 45. In Figure 45, the solid line indicates In each sample, the silicon nitride film formed as the insulating film 1911 was formed at a temperature of 220°C. The dashed line indicates 350°C. The black markers indicate the oxidation temperature of each sample. After forming the semiconductor film 1905 or the multilayer film 1906, a heat treatment was performed at 350°C. The white markers indicate the oxide semiconductor film 1905 or the multilayer film 1906 formed thereon. The triangle markers indicate that each sample was subjected to a heat treatment at 450° C. 05, i.e., sample 2a, and the circle marker indicates that the sample has a multilayer film 1906. This indicates that the sample has the same structure as sample 3a, i.e., sample 3a.

[0438] As can be seen from FIG. 45, Samples 2a and 3a have low sheet resistance and are suitable as electrodes for capacitor elements. It can be seen that the desired sheet resistance value of 0.2 M / sq or less is satisfied. It can be seen that the time fluctuation of the sheet resistance value is small for Sample 2a and Sample 3a. The oxide semiconductor film or multilayer film in contact with the silicon nitride film is subjected to high temperature and high humidity conditions. Since the fluctuation of the resistance value is small, it can be used as a light-transmitting conductive film for the electrodes of a capacitor element. You can be there.

[0439] Next, for Sample 2a and Sample 3a, the substrate temperatures were set to 25°C, 60°C, and 150°C. The results of measuring the sheet resistance of each sample are shown in FIG. As for the sample 3a, the silicon nitride film formed as the insulating film 1911 was formed at a temperature of 220 The sample was subjected to a heat treatment at 350°C after forming the multilayer film 1906.

[0440] From Figure 46, it can be seen that the sheet resistance of the multilayer film 1906 does not change even when the substrate temperature is increased. That is, the oxide semiconductor film or multilayer film in contact with the silicon nitride film is also a degenerate semiconductor. The oxide semiconductor film or multilayer film in contact with the silicon nitride film remains stable even when the substrate temperature changes. Since the fluctuation amount of the sheet resistance value is small, it can be used as a light-transmitting conductive film for an electrode of a capacitor element. It can be used as such.

[0441] The configuration shown in this embodiment may be appropriately combined with the configurations shown in other embodiments or examples. It can be used. [Example]

[0442] In this example, impurity analysis of an oxide semiconductor film and an insulating film formed on the oxide semiconductor film was performed. This will be explained using FIG.

[0443] In this example, two types of samples (hereinafter referred to as samples) were used for impurity analysis. 5 and sample 6) were prepared.

[0444] First, the method for preparing Sample 5 will be described below.

[0445] For sample 5, an IGZO film was formed on a glass substrate, and then a silicon nitride film was formed. After that, heat treatment was carried out at 450°C for 1 hour in a nitrogen atmosphere, and then in a mixed gas atmosphere of nitrogen and oxygen. Heat treatment was carried out at 450°C for 1 hour in an atmosphere (nitrogen = 80%, oxygen = 20%).

[0446] The conditions for forming the IGZO film are as follows: sputtering with a metal oxide target (In:Ga:Zn=1:1:1) and Ar / O2=100 / 100sccm (O2 = 50%), pressure = 0.6 Pa, deposition power = 5000 W, substrate temperature = 170 °C. A 1000 nm thick IGZO film was deposited.

[0447] The silicon nitride film was formed under the following conditions: SiH4 / N2 / N H3=50 / 5000 / 100sccm, pressure=100Pa, deposition power=1000W, A silicon nitride film having a thickness of 100 nm was formed under the condition of a plate temperature of 220°C.

[0448] Next, a method for preparing Sample 6 will be described below.

[0449] An IGZO film is formed on a glass substrate, and then a silicon oxynitride film and a silicon nitride film are formed. After that, a heat treatment was carried out at 450°C for 1 hour in a nitrogen atmosphere, and then Heat treatment at 450°C for 1 hour in a mixed gas atmosphere of nitrogen and oxygen (nitrogen = 80%, oxygen = 20%) The theory was carried out.

[0450] The deposition conditions for the IGZO film and the silicon nitride film were the same as those for sample 5. The conditions for forming the silicon oxynitride film were as follows: SiH4 / N2O=30 / 4000sccm, pressure=40Pa, deposition power=150W, A silicon oxynitride film with a thickness of 50 nm was formed under the condition of a plate temperature of 220°C, and then PE -CVD method, SiH4 / N2O=160 / 4000sccm, pressure=200Pa, synthesis A silicon oxynitride film with a thickness of 400 nm was deposited under the conditions of film power = 1500 W and substrate temperature = 220°C. A film was formed.

[0451] The results of the impurity analysis of Samples 5 and 6 are shown in FIG.

[0452] The impurity analysis was carried out using secondary ion mass spectrometry (SIMS). Using Ion Mass Spectrometry, the analysis was performed in the direction of the arrow shown in Figure 42. That is, measurements were taken from the glass substrate side.

[0453] Also, Figure 42(A) shows the concentration profile of hydrogen (H) obtained by measuring sample 5. FIG. 42(B) shows the concentration profile of hydrogen (H) obtained by measuring sample 6. do.

[0454] From Figure 42(A), the hydrogen (H) concentration in the IGZO film is 1.0×10 20 atoms / c m 3 In addition, the hydrogen (H) concentration in the silicon nitride film is 1.0 × 10 2 3 atoms / cm 3 In addition, from Figure 42(B), it can be seen that the hydrogen in the IGZO film (H) concentration is 5.0 × 10 19 atoms / cm 3 In addition, nitric oxide The hydrogen (H) concentration in the silicon dioxide film is 3.0×10 21 atoms / cm 3 That is I understand.

[0455] Due to its measurement principle, SIMS analysis does not detect the area near the sample surface or the layer boundary between films of different materials. It is known that it is difficult to obtain accurate data near the surface. When analyzing the distribution of hydrogen (H) in the thickness direction by SIMS, the area where the target film exists is In the range, there is no extreme fluctuation and the average value in the area where almost constant intensity is obtained is used. do.

[0456] In this way, by changing the composition of the insulating film in contact with the IGZO film, the water in the IGZO film Differences were observed in the hydrogen (H) concentration.

[0457] For example, when the above-mentioned IGZO film is used in the channel formation region of a transistor, Sample 6 As shown in Fig. 1, it is preferable to provide a silicon oxynitride film in contact with the IGZO film. As shown in sample 5, an IGZO film is used as a transparent conductive film for the electrodes of the quantum well. It is preferable to provide a silicon nitride film in contact with the silicon nitride film. IGZO film used in the channel formation region of transistors and IGZO used in the electrodes of capacitor elements The hydrogen concentration in the IGZO film can be changed even when the O film is fabricated in the same process. [Example]

[0458] In this example, the defect amounts of the oxide semiconductor film and the multilayer film were measured using FIGS. 43 and 44. I will explain.

[0459] First, the structure of the sample will be described.

[0460] Sample 7 is a 35 nm thick oxide semiconductor film formed on a quartz substrate and a 35 nm thick oxide semiconductor film and a nitride insulating film having a thickness of 100 nm formed thereon.

[0461] Samples 8 and 9 are a 30 nm thick multilayer film formed on a quartz substrate and a 30 nm thick multilayer film formed on the multilayer film. The multilayer film of Sample 8 has a thickness of 100 nm. a first oxide film having a thickness of 10 nm, an oxide semiconductor film having a thickness of 10 nm, and a second oxide film having a thickness of 10 nm. The sample 9 has a first oxide film with a thickness of 20 nm, a second oxide film with a thickness of 15 nm, and a third oxide film with a thickness of 15 nm. A 10-nm-thick oxide semiconductor film and a 10-nm-thick second oxide film were stacked in this order. Sample 9 differs from Sample 7 in that it has a multilayer film instead of an oxide semiconductor film. .

[0462] Sample 10 is a 100 nm thick oxide semiconductor film formed on a quartz substrate and a 100 nm thick oxide semiconductor film. A 250 nm thick oxide insulating film was formed on the solid film, and a 10 nm thick film was formed on the oxide insulating film. The sample 10 has an oxide semiconductor film and a nitride insulating film with a thickness of 0 nm. The difference is that the film is not in contact with the nitride insulating film but is in contact with the oxide insulating film.

[0463] Next, the method for preparing each sample will be described.

[0464] First, the method for preparing sample 7 will be described.

[0465] A 35 nm thick IGZO film was formed on a quartz substrate as an oxide semiconductor film. The film was formed by sputtering using a metal oxide target (In:Ga:Z n = 1:1:1, Ar / O2 = 100sccm / 100sccm (O2 = 50%) ), pressure = 0.6 Pa, film formation power = 5000 W, and substrate temperature = 170°C.

[0466] Next, as a first heat treatment, a heat treatment was performed in a nitrogen atmosphere at 450°C for 1 hour, and then Heating for 1 hour in a nitrogen and oxygen mixed gas atmosphere (nitrogen = 80%, oxygen = 20%) at 450℃ Processing was carried out.

[0467] Next, a silicon nitride film having a thickness of 100 nm is formed as a nitride insulating film on the oxide semiconductor film. The conditions for forming the silicon nitride film were SiH4 / N2 / NH 3=50 / 5000 / 100sccm, pressure=100Pa, deposition power=1000W, substrate The temperature was 350°C.

[0468] Next, as a second heat treatment, heat treatment was performed at 250° C. in a nitrogen atmosphere for 1 hour.

[0469] Sample 7 was prepared by the above steps.

[0470] Next, a method for preparing Sample 8 will be described.

[0471] In Sample 8, a multilayer film was formed instead of the oxide semiconductor film of Sample 7. The multilayer film was A metal oxide target (In:Ga:Zn=1: 3:2), Ar / O2 = 180 / 20sccm (O2 = 10%), pressure = 0.6P a) A first oxide film having a thickness of 10 nm was formed under the conditions of a deposition power of 5000 W and a substrate temperature of 25°C. Next, a metal oxide target (In:Ga:Zn=1 :1:1) was used, Ar / O2 = 100 / 100sccm (O2 = 50%), pressure = 0. 6 Pa, deposition power = 5000 W, substrate temperature = 170 °C, and oxide semiconductor with a thickness of 10 nm. Next, a metal oxide target (In:Ga:Z) was used for sputtering. n = 1:3:2), Ar / O2 = 180 / 20sccm (O2 = 10%), pressure = The second acid film was deposited to a thickness of 10 nm under the conditions of 0.6 Pa, deposition power = 5000 W, and substrate temperature = 25°C. A nitride film was formed.

[0472] The other steps were the same as those for Sample 7. Sample 8 was formed by the above steps.

[0473] Next, a method for preparing Sample 9 will be described.

[0474] In Sample 9, a multilayer film was formed instead of the oxide semiconductor film of Sample 7. The multilayer film was A first oxide film having a thickness of 20 nm was formed on a quartz substrate under the same conditions as those for the first oxide film shown in Sample 8. Next, an oxide film was formed by a sputtering method, which was the same as the oxide semiconductor film shown in Sample 8. A 15-nm-thick oxide semiconductor film was formed under the conditions described above. A second oxide film was deposited to a thickness of 10 nm using the same conditions as for the oxide film.

[0475] The other steps were the same as those for Sample 7. Sample 9 was formed through the above steps.

[0476] Next, a method for preparing the sample 10 will be described.

[0477] Sample 10 is a sample obtained by growing an oxide semiconductor film 100 nm thick on a quartz substrate under the same conditions as Sample 7. was formed.

[0478] Next, the first heat treatment was carried out under the same conditions as those for Sample 7.

[0479] Next, a first silicon oxynitride film having a thickness of 50 nm was formed as an oxide insulating film over the oxide semiconductor film. A silicon nitride film and a second silicon oxynitride film with a thickness of 200 nm were formed. D method, SiH4 / N2O=30 / 4000sccm, pressure=40Pa, film formation power=1 A first silicon oxynitride film was formed to a thickness of 50 nm under the conditions of 50 W and substrate temperature = 220 °C. Then, by PE-CVD, SiH4 / N2O=160 / 4000sccm, pressure = 200 Pa, deposition power = 1500 W, substrate temperature = 220 °C, A second silicon oxynitride film was formed. Note that the second silicon oxynitride film was formed at a stoichiometric ratio. The film contains more oxygen than meets the compositional requirements.

[0480] Next, using the same conditions as Sample 7, a silicon nitride film with a thickness of 100 nm was formed on the oxide insulating film. Formed.

[0481] Next, a second heat treatment was carried out under the same conditions as for Sample 7.

[0482] Sample 10 was formed through the above steps.

[0483] Next, ESR measurements were carried out on Samples 7 to 10. The ESR measurements were carried out at a predetermined temperature. From the magnetic field value (H0) at which microwave absorption occurs, the g value can be calculated using the formula g=hν / βH0. The following parameters are obtained. Note that ν is the microwave frequency. h is Planck's constant. and β is the Bohr magneton, both of which are constants.

[0484] Here, ESR measurements were carried out under the following conditions: The measurement temperature was room temperature (25°C), and the The 2GHz radio frequency power (microwave power) was set to 20mW, and the magnetic field direction was set to the same as that of the prepared sample. The film surface was parallel to the

[0485] The primary oxide semiconductor films and multilayer films included in Samples 7 to 9 were measured by ESR. The differential curves are shown in Figure 43. Figure 43(A) shows the measurement results for sample 7, and Figure 43(B) shows the 43(A) shows the measurement results for sample 8, and FIG. 43(B) shows the measurement results for sample 9.

[0486] The first derivative curve obtained by ESR measurement of the oxide semiconductor film included in Sample 10 is shown in Figure 44. show.

[0487] In Fig. 43(A) to Fig. 43(C), sample 7 shows that the oxide A symmetric signal due to defects in the semiconductor film was detected. Samples 8 and 9 At a g value of 1.95, a signal with symmetry due to defects in the multilayer film was detected. The spin density of sample 7 with a g value of 1.93 is 2.5 × 10 19 spins / c m 3 The sum of the spin densities for g values ​​of 1.93 and 1.95 in sample 8 is 1.6 x10 19 spins / cm 3 The g values ​​of sample 9 are 1.93 and 1.95. The total pin density is 2.3 x 10 19 spins / cm 3 That is, oxide semiconductor It can be seen that the oxide semiconductor film and the multilayer film contain defects. An example of a defect is an oxygen vacancy.

[0488] In FIG. 44, Sample 10 is a composite of the oxide semiconductor film of Sample 7, the multilayer film of Sample 8, and the multilayer film of Sample 9. In comparison, the symmetric signal due to defects is observed even though the oxide semiconductor film is thick. No signal was detected, i.e., below the detection limit (here, the detection limit is 3.7 × 10 16 spin s / cm 3 From this, it was found that the number of defects contained in the oxide semiconductor film was I know I can't.

[0489] The oxide semiconductor film or multilayer film is covered with a nitride insulating film, in this case, a nitride insulating film formed by PE-CVD. When the silicon film comes into contact with the oxide semiconductor film or multilayer film, defects, typically oxygen vacancies, are formed. On the other hand, when an oxide insulating film, a silicon oxynitride film, is used for an oxide semiconductor film, When the oxygen concentration is increased, the excess oxygen contained in the silicon oxynitride film, i.e., the oxygen content of the silicon oxynitride film is reduced. Therefore, more oxygen diffuses into the oxide semiconductor film than in the case of the oxide semiconductor film, and defects in the oxide semiconductor film are not increased.

[0490] From the above, as shown in Samples 7 to 9, the oxide semiconductor film in contact with the nitride insulating film Alternatively, the multilayer film has many defects, typically oxygen vacancies, and is highly conductive, making it difficult to form electrodes for capacitor elements. On the other hand, as shown in Sample 10, the oxide semiconductor in contact with the oxide insulating film can be used as a The conductive film has a small amount of oxygen vacancy and low conductivity, so it is suitable for use as a channel formation region for transistors. It can be used as follows.

[0491] Here, the reason why the resistivity of the oxide semiconductor film and the multilayer film in contact with the nitride insulating film decreases is as follows. This will be described below.

[0492] <Energy and Stability between Existence Forms of H> First, the energy difference and stability of the forms of H present in the oxide semiconductor film will be described using the calculation results. Here, InGaZnO4 was used as the oxide semiconductor film.

[0493] The structure used in the calculation was based on an 84-atom bulk model obtained by doubling the hexagonal unit cell of the InGaZnO4 crystal in the a-axis and b-axis directions.

[0494] In the bulk model, a model was prepared in which one O atom bonded to three In atoms and one Zn atom was replaced by a H atom (see Fig. 47(A)). Also, in Fig. 47(A), a view of the ab plane in the InO layer as seen from the c-axis is shown in Fig. 47(B). The region where one O atom bonded to three In atoms and one Zn atom was removed is indicated as an oxygen vacancy Vo, and is shown by a broken line in Fig. 47( A) and Fig. 47(B). Also, the H atom located in the oxygen vacancy Vo is denoted as V oH.

[0495] Also, in the bulk model, one O atom bonded to three In atoms and one Zn atom was removed to form an oxygen vacancy (Vo). In the vicinity of the Vo, a model in which a H atom is bonded to an O atom bonded to one Ga atom and two Zn atoms with respect to the ab plane was prepared (see Fig. 47( C)). Also, in Fig. 47(C), a view of the ab plane in the InO layer as seen from the c-axis is shown in Fig. 47(D). In Fig. 47(C) and Fig. 47(D), the oxygen vacancy Vo is indicated by a broken line In addition, a model having a Vo and a H atom bonded to an O atom bonded to one Ga atom and two Zn atoms in the vicinity of the oxygen vacancy Vo is denoted as Vo + H.​

[0496] For the above two models, an optimization calculation was performed with the lattice constant fixed, and the total energy was calculated. Note that the smaller the value of the total energy, the more stable the structure can be said to be.

[0497] For the calculation, the first-principles calculation software VASP (The Vienna Ab initio simulation package) was used. The calculation conditions are shown in Table 1. tio simulation package) was used. The calculation conditions are shown in Table 1.

[0498] [Table 1] For the calculation of the electronic state pseudo-potential, the potential generated by the Projector Augmented Wave (PAW) method was used, and for the functional, GGA / PBE (Generalized-Gradient-Approximation / Perdew-Bur ke-Ernzerhof) was used. ke-Ernzerhof) was used.

[0499] Also, the total energies of the two models calculated by the calculation are shown in Table 2.

[0500] [Table 2]

[0501] From Table 2, the total energy of VoH is 0.78 eV smaller than that of Vo + H. Therefore, it can be said that VoH is more stable than Vo + H. Therefore, when a H atom approaches an oxygen vacancy (Vo), the H atom is more likely to be incorporated into the oxygen vacancy (Vo) rather than bonding with an O atom. it can be considered that it is more likely to be incorporated into the oxygen vacancy (Vo) rather than bonding with an O atom. it can be considered that it is more likely to be incorporated into the oxygen vacancy (Vo) rather than bonding with an O atom.

[0502] <Thermodynamic state of VoH> Next, the formation energy and charge state of VoH, where an H atom is incorporated into an oxygen vacancy (Vo), The calculation results are explained below. The formation energy of VoH varies depending on the charge state. , and also depends on the Fermi energy. Therefore, VoH depends on the Fermi energy and is stable. Here, the state where VoH releases one electron is called (VoH) + and indicated The state in which one electron is captured is (VoH) - and the state without electron movement is expressed as (VoH ) 0 (VoH) + , (VoH) - , (VoH) 0 The formation energy of each is calculated. I calculated.

[0503] The calculations were performed using the first-principles calculation software VASP. The calculation conditions are shown in Table 3.

[0504] [Table 3]

[0505] Projector Augmented Wave for electronic state pseudopotential calculation The potential generated by the PAW method is used as the functional. The HSE-Ernzerhof DFT hybrid functional (HSE06) was used.

[0506] In addition, the formation energy of oxygen vacancies is calculated assuming a dilute limit of oxygen vacancy concentration. The energy was calculated by correcting for the excess broadening of electrons and holes into the conduction band and valence band. The energy origin is the top of the valence band of a perfect crystal, and the deviation of the valence band due to the defect structure is Corrections were made using the average electrostatic potential.

[0507] In Figure 48(A), (VoH) + , (VoH) - , (VoH) 0 The respective formation energies The horizontal axis is the Fermi level, and the vertical axis is the formation energy. The solid line indicates the ) + The dashed line indicates the formation energy of (VoH) 0 The dashed line indicates the formation energy of (VoH) - The formation energy of VOH is shown. Also, the charge of VOH is (VOH) + From (Vo H) 0 Through (VoH) - The transition level between these two is denoted as ε(+ / -).

[0508] Figure 48(B) shows the thermodynamic transition level of VoH. The energy gap of 4 was 2.739 eV. The valence band energy was 0 e V, the transition level (ε(+ / -)) is 2.62 eV, which is located just below the conduction band. This indicates that the incorporation of H atoms into oxygen vacancies (Vo) results in the formation of InGaZ It can be seen that nO4 becomes n-type.

[0509] When the oxide semiconductor film is exposed to plasma, the oxide semiconductor film is damaged, and the oxide semiconductor Defects, typically oxygen vacancies, are generated in the conductive film. When the nitride insulating film comes into contact with the oxide semiconductor film, hydrogen contained in the nitride insulating film moves to the oxide semiconductor film. Hydrogen enters the oxygen vacancies in the oxide semiconductor film, forming VoH in the oxide semiconductor film. As a result, the oxide semiconductor film becomes n-type and the resistivity decreases. The oxide semiconductor film in contact with the oxide semiconductor film can be used as an electrode of a capacitor. [Explanation of symbols]

[0510] 11 Oxide semiconductor film 12 Gate insulating film 13a Drain electrode 15 Dual-Gate Transistor 16 Conductive film 17a Gate electrode 19a Source electrode 29 Insulating film 31 insulating film 32 insulating film 92 Wiring 94 Aperture 100 pixel unit 101 pixels 102 Circuit Board 103 Transistor 104 Scanning line driving circuit 105 Capacitive element 106 Signal line driver circuit 107 scan lines 107a Gate electrode 108 Liquid crystal element 109 Signal Line 109a Source electrode 111 Oxide semiconductor film 113 Conductive film 113a Drain electrode 115 Capacitance Line 117 Aperture 119 Oxide semiconductor film 121 pixel electrode 123 Aperture 125 Conductive Film 126 insulating film 127 Gate insulating film 128 insulating film 129 insulating film 130 insulating film 131 insulating film 132 insulating film 133 Insulating Film 134 Organic insulating film 141 pixels 143 Aperture 145 Capacitive element 146 Capacitor 150 boards 151 pixels 152 Light-shielding film 154 Counter electrode 156 Alignment film 158 Alignment film 160 LCD 161 pixels 167 Conductive Film 169 Transistors 171 pixels 172 pixels 173 Capacitor 174 Capacitive element 175 Capacitance Line 176 Capacitance Line 177 Oxide semiconductor film 178 Oxide semiconductor film 182 Channel protection film 183 Transistor 185 transistors 187 Conductive Film 190 transistors 191 Signal Line 191a Source electrode 193 Conductive Film 193a Drain electrode 195 Oxide semiconductor film 196 pixels 197 Capacitor 198 Oxide semiconductor film 199 Conductive Film 201 pixels 205 Capacitor 218 Gate insulating film 221 pixel electrode 226 Insulating Film 227 Insulating Film 228 insulating film 229 Insulating Film 230 insulating film 231 Insulating Film 232 insulating film 233 Insulating Film 245 Capacitor 297 Transistors 299a Oxide semiconductor film 299b Oxide semiconductor film 299c Oxide semiconductor film 301 pixels 305 Capacitor 319 Oxide semiconductor film 401_1 pixel 401_2 pixels 403_1 Transistor 403_2 Transistor 405_1 Capacitor element 405_2 Capacitor element 407_1 scan line 407_2 scan line 409 Signal Line 411_1 Semiconductor film 411_2 Semiconductor film 413_1 Conductive film 413_2 Conductive film 415 Capacitance Line 417_1 Aperture 417_2 Aperture 419_1 Semiconductor film 419_2 Semiconductor film 421_1 Pixel electrode 421_2 Pixel electrode 423 Aperture 425 Conductive Film 901 Circuit Board 902 Pixel section 903 Signal line driver circuit 904 Scanning line driver circuit 905 Sealing material 906 Circuit Board 908 LCD 910 Transistor 911 Transistor 913 Liquid crystal element 915 Connection terminal electrode 916 Terminal electrode 917 Conductive film 918 FPC 918b FPC 919 Anisotropic conductive agent 922 Gate insulating film 923 Insulating Film 924 insulating film 925 sealing material 926 Capacitor 927 Oxide semiconductor film 928 Electrode membrane 929 Capacitance Line 930 electrode 931 Electrode 932 insulating film 933 Insulating Film 935 Spacer 940 electrode 941 Electrode 943 Liquid crystal elements 945 Conductive film 946 Capacitance Line 971 Source electrode 973 Drain electrode 975 Common potential line 977 Common electrode 985 Common potential line 987 Common electrode 1901 Glass substrate 1903 insulating film 1904 insulating film 1905 Oxide semiconductor film 1906 Multilayer film 1907 Conductive film 1909 Conductive film 1910 insulating film 1911 insulating film 1913 Opening 1915 Opening 1917 Opening 1919 Opening 9000 tables 9001 Case 9002 Legs 9003 Display section 9004 Display button 9005 Power Cord 9033 Fasteners 9034 Switch 9035 Power Switch 9036 Switch 9038 Operation switch 9100 Television equipment 9101 Housing 9103 Display section 9105 Stand 9107 Display section 9109 Operation key 9110 Remote control device 9201 Main Unit 9202 Housing 9203 Display section 9204 keyboard 9205 External connection port 9206 Pointing Device 9630 chassis 9631 Display section 9631a Display section 9631b Display section 9632a area 9632b area 9633 Solar Cells 9634 Charge / Discharge Control Circuit 9635 Battery 9636 DC / DC Converter 9637 Converter 9638 Operation Key 9639 Button

Claims

1. It has a pixel section having multiple pixels and a circuit section, At least one of the pixels comprises a first transistor and a liquid crystal element. The circuit section is a liquid crystal display device having at least a second transistor, A first conductive layer having the function of a gate electrode of the first transistor, A first insulating layer having a region in contact with the upper surface of the first conductive layer, A first oxide semiconductor layer having a region that overlaps with the first conductive layer and having a channel formation region for the first transistor, A second conductive layer having a region in contact with the first oxide semiconductor layer and functioning as either the source electrode or the drain electrode of the first transistor, A second insulating layer having a region in contact with the upper surface of the second conductive layer, A third conductive layer is electrically connected to the second conductive layer and functions as the first electrode of the liquid crystal element, A fourth conductive layer having overlap with the third conductive layer and functioning as the second electrode of the liquid crystal element, A fifth conductive layer is electrically connected to the fourth conductive layer and functions as a capacitance line, A second oxide semiconductor layer having a channel formation region for the second transistor, A sixth conductive layer having a region overlapping with the second oxide semiconductor layer and functioning as the gate electrode of the second transistor, A seventh conductive layer having the same material as the second conductive layer and having at least a portion of its upper surface in contact with the second insulating layer, The first oxide semiconductor layer has a stacked structure, Each layer in the stacked structure of the first oxide semiconductor layer contains In, Ga, and Zn, and the atomic ratios in each layer are different from those of the others. The fifth conductive layer is electrically connected to the sixth conductive layer via the seventh conductive layer in the region outside the pixel portion. The fifth conductive layer has the same material as the first conductive layer, and at least a portion of its upper surface is in contact with the first insulating layer. In a plan view of the pixel portion, the channel length direction of the first transistor has a region that extends along the first direction, In a plan view of the pixel portion, the first conductive layer has a region extending along the first direction, In a plan view of the pixel portion, the fifth conductive layer has a region extending along the first direction, In a plan view of the circuit section, the channel length direction of the second transistor has a region that extends along a second direction intersecting the first direction, wherein the liquid crystal display device.

2. It has a pixel section having multiple pixels and a circuit section, At least one of the pixels comprises a first transistor and a liquid crystal element. The circuit section is a liquid crystal display device having at least a second transistor, A first conductive layer having the function of a gate electrode of the first transistor, A first insulating layer having a region in contact with the upper surface of the first conductive layer, A first oxide semiconductor layer having a region that overlaps with the first conductive layer and having a channel formation region for the first transistor, A second conductive layer having a region in contact with the first oxide semiconductor layer and functioning as either the source electrode or the drain electrode of the first transistor, A second insulating layer having a region in contact with the upper surface of the second conductive layer, A third conductive layer is electrically connected to the second conductive layer and functions as the first electrode of the liquid crystal element, A fourth conductive layer having overlap with the third conductive layer and functioning as the second electrode of the liquid crystal element, A fifth conductive layer is electrically connected to the fourth conductive layer and functions as a capacitance line, A second oxide semiconductor layer having a channel formation region for the second transistor, A sixth conductive layer having a region overlapping with the second oxide semiconductor layer and functioning as the gate electrode of the second transistor, A seventh conductive layer having the same material as the second conductive layer and having at least a portion of its upper surface in contact with the second insulating layer, The first oxide semiconductor layer has a stacked structure, Each layer in the stacked structure of the first oxide semiconductor layer contains In, Ga, and Zn, and the atomic ratios in each layer are different from those of the others. The fifth conductive layer is electrically connected to the sixth conductive layer via the seventh conductive layer in the region outside the pixel portion. The fifth conductive layer has the same material as the first conductive layer, and at least a portion of its upper surface is in contact with the first insulating layer. In a plan view of the pixel portion, the channel length direction of the first transistor has a region that extends along the first direction, In a plan view of the pixel portion, the first conductive layer has a region extending along the first direction, In a plan view of the pixel portion, the fifth conductive layer has a region extending along the first direction, In a plan view, the channel length direction of the second transistor has a region that extends along a second direction intersecting the first direction. In a plan view, the fifth conductive layer has a region extending along the second direction, wherein the liquid crystal display device.

3. In claim 1 or 2, In a plan view, the first oxide semiconductor layer overlaps the entire area with the first conductive layer in a liquid crystal display device.