JP7026717B2 - Semiconductor device - Google Patents

Description

One aspect of the present invention relates to a semiconductor device having an oxide semiconductor film and a display device having the semiconductor device.

It should be noted that one aspect of the present invention is not limited to the above technical fields. The technical field of one aspect of the invention disclosed in the present specification and the like relates to a product, a method, or a manufacturing method. Alternatively, the invention relates to a process, machine, manufacture, or composition (composition of matter). In particular, one aspect of the present invention relates to a semiconductor device, a display device, a light emitting device, a power storage device, a storage device, a driving method thereof, or a method for manufacturing the same.

In the present specification and the like, the semiconductor device refers to all devices that can function by utilizing the semiconductor characteristics. A semiconductor circuit, an arithmetic unit, and a storage device, including a semiconductor element such as a transistor, are one aspect of a semiconductor device. Imaging devices, display devices, liquid crystal display devices, light emitting devices, electro-optical devices, power generation devices (including thin-film solar cells, organic thin-film solar cells, etc.), and electronic devices
May have a semiconductor device.

Attention is being paid to a technique for constructing a transistor (also referred to as a field effect transistor (FET) or a thin film transistor (TFT)) using a semiconductor thin film formed on a substrate having an insulating surface. The transistor is widely applied to electronic devices such as integrated circuits (ICs) and image display devices (display devices). Semiconductor materials typified by silicon are widely known as semiconductor thin films applicable to transistors, but oxide semiconductors are attracting attention as other materials.

For example, a technique for manufacturing a transistor using an amorphous oxide containing In, Zn, Ga, Sn and the like as an oxide semiconductor is disclosed (see Patent Document 1). Further, a technique for producing a transistor of an oxide thin film having a self-aligned top gate structure is disclosed (see Patent Document 2).

Further, a semiconductor device is disclosed in which an insulating layer that releases oxygen by heating is used as the underlying insulating layer of the oxide semiconductor layer forming a channel to reduce oxygen deficiency in the oxide semiconductor layer (see Patent Document 3). ).

Japanese Unexamined Patent Publication No. 2006-165529 Japanese Unexamined Patent Publication No. 2009-278115 Japanese Unexamined Patent Publication No. 2012-09836

Examples of the transistor having an oxide semiconductor film include an inverted stagger type (also referred to as a bottom gate structure) and a stagger type (also referred to as a top gate structure). When a transistor having an oxide semiconductor film is applied to a display device, an inverted stagger type transistor may be used rather than a stagger type transistor because the manufacturing process is relatively simple and the manufacturing cost can be suppressed. many. However, the screen of the display device is enlarged, or the image quality of the display device is improved (for example, 4k × 2k (horizontal pixel number = 3840 pixels, vertical pixel number = 2160 pixels) or 8k × 4k (horizontal pixel). Number = 7680 pixels, number of vertical pixels =
As the high-definition display device (4320 pixels) and the like progresses, in the reverse stagger type transistor, there is a parasitic capacitance between the gate electrode and the source electrode and the drain electrode, so that the parasitic capacitance causes signal delay and the like. There is a problem that the image becomes large and the image quality of the display device deteriorates. Therefore, it is desired to develop a structure having stable semiconductor characteristics and high reliability for a staggered transistor having an oxide semiconductor film.

Further, when a transistor is manufactured using an oxide semiconductor film in the channel region, oxygen deficiency formed in the channel region of the oxide semiconductor film affects the transistor characteristics, which is a problem. For example, when oxygen deficiency is formed in the channel region of the oxide semiconductor film, carriers are generated due to the oxygen deficiency. When carriers are generated in the channel region of the oxide semiconductor film, the electrical characteristics of the transistor having the oxide semiconductor film in the channel region fluctuate.
Typically, a threshold voltage shift occurs. In addition, there is a problem that the electrical characteristics vary from transistor to transistor. Therefore, in the channel region of the oxide semiconductor film, it is preferable that there is less oxygen deficiency. On the other hand, in a transistor using an oxide semiconductor film in the channel region, the oxide semiconductor film in contact with the source electrode and the drain electrode has many oxygen deficiencies in order to reduce the contact resistance between the source electrode and the drain electrode, and the resistance is high. Lower is preferable.

In view of the above problems, one aspect of the present invention is to suppress fluctuations in electrical characteristics and improve reliability in a transistor having an oxide semiconductor. or,
One aspect of the present invention is to provide a staggered transistor having an oxide semiconductor. Alternatively, one aspect of the present invention is to provide a transistor having an oxide semiconductor and having a large on-current. Alternatively, one aspect of the present invention is to provide a transistor having an oxide semiconductor and having a small off-current. Alternatively, one aspect of the present invention is to provide a semiconductor device with reduced power consumption.
Alternatively, one aspect of the present invention is to provide a novel semiconductor device.

The description of the above-mentioned problem does not prevent the existence of other problems. It should be noted that one aspect of the present invention does not necessarily have to solve all of these problems. Issues other than the above are self-evident from the description of the specification and the like, and it is possible to extract problems other than the above from the description of the specification and the like.

One aspect of the present invention is a semiconductor device having a transistor, wherein the transistor is the first.
Gate electrode, first gate insulating film on the first gate electrode, first oxide semiconductor film on the first gate insulating film, and second gate on the first oxide semiconductor film. It has an insulating film and a second oxide semiconductor film on the second gate insulating film, and the first oxide semiconductor film has a channel region on which the second oxide semiconductor film is superimposed and a channel region. It has a source region provided in contact with the channel region and a drain region provided in contact with the channel region, and the channel region includes a first layer and a first layer.
It has a second layer that is in contact with the upper surface of the first layer and covers the side surface of the first layer in the channel width direction, and the second oxide semiconductor film is more than the first oxide semiconductor film. It is a semiconductor device with a high carrier density.

Further, another aspect of the present invention is a semiconductor device having a transistor, wherein the transistor has a first gate electrode, a first gate insulating film on the first gate electrode, and a first gate insulation. A first oxide semiconductor film on the film, a second gate insulating film on the first oxide semiconductor film, and the like.
It has a second oxide semiconductor film on the second gate insulating film, and the first oxide semiconductor film is provided in contact with the channel region on which the second oxide semiconductor film is superimposed and the channel region. It has a source region to be formed and a drain region provided in contact with the channel region, and the first oxide semiconductor film is in contact with the channel region on which the second oxide semiconductor film is superimposed and the second insulating film. It has a source region and a drain region to which the second insulating film is in contact, and the channel region is in contact with the first layer and the upper surface of the first layer, and the side surface of the first layer in the channel width direction. A semiconductor device having a second layer to cover and a third layer in contact with the lower surface of the first layer, and the second oxide semiconductor film is a semiconductor device having a higher carrier density than the first oxide semiconductor film. be.

Further, in the above embodiment, the transistor is further provided in the insulating film on the second oxide semiconductor film, the source electrode connected to the source region via the opening provided in the insulating film, and the insulating film. It is preferable to have a drain electrode connected to the drain region through the opening.

Further, in the above embodiment, the source region and the drain region preferably have one or more of hydrogen, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, or a rare gas.

Further, in the above embodiment, either or both of the first oxide semiconductor film and the second oxide semiconductor film are In, Zn, and M (M is Al, Ga, Y, or Sn). , Is preferred. Further, in the above embodiment, it is preferable that either or both of the first oxide semiconductor film and the second oxide semiconductor film has a crystal portion, and the crystal portion has a c-axis orientation.

Further, another aspect of the present invention is a display device having the semiconductor device and the display element according to any one of the above aspects. Further, another aspect of the present invention is a display module having the display device and a touch sensor. Further, another aspect of the present invention is an electronic device having the semiconductor device, the display device, or the display module according to any one of the above aspects, and an operation key or a battery.

According to one aspect of the present invention, in a transistor having an oxide semiconductor, fluctuations in electrical characteristics can be suppressed and reliability can be improved. Alternatively, according to one aspect of the present invention.
It is possible to provide a staggered transistor having an oxide semiconductor. Alternatively, according to one aspect of the present invention, it is possible to provide a transistor having an oxide semiconductor and having a large on-current. Alternatively, according to one aspect of the present invention, it is possible to provide a transistor having an oxide semiconductor and having a small off-current. Alternatively, according to one aspect of the present invention, it is possible to provide a semiconductor device with reduced power consumption. Alternatively, according to one aspect of the present invention, a novel semiconductor device can be provided.

The description of these effects does not preclude the existence of other effects. It should be noted that one aspect of the present invention does not necessarily have to have all of these effects. It should be noted that the effects other than these are self-evident from the description of the description, drawings, claims, etc., and it is possible to extract the effects other than these from the description of the description, drawings, claims, etc. Is.

The figure explaining the upper surface and the cross section of a semiconductor device. The figure explaining the upper surface and the cross section of a semiconductor device. The figure explaining the upper surface and the cross section of a semiconductor device. The figure explaining the upper surface and the cross section of a semiconductor device. The figure explaining the upper surface and the cross section of a semiconductor device. The figure explaining the upper surface and the cross section of a semiconductor device. The figure explaining the upper surface and the cross section of a semiconductor device. The figure explaining the band structure. The figure explaining the cross section of the manufacturing method of a semiconductor device. The figure explaining the cross section of the manufacturing method of a semiconductor device. The figure explaining the cross section of the manufacturing method of a semiconductor device. The figure explaining the cross section of the manufacturing method of a semiconductor device. The figure explaining the structural analysis of CAAC-OS and a single crystal oxide semiconductor by XRD, and the figure which shows the selected area electron diffraction pattern of CAAC-OS. A cross-sectional TEM image of the CAAC-OS, a planar TEM image, and an image analysis image thereof. The figure which shows the electron diffraction pattern of nc-OS, and the cross-sectional TEM image of nc-OS. Cross-sectional TEM image of a-like OS. The figure which shows the change of the crystal part by electron irradiation of In—Ga—Zn oxide. Top view showing one aspect of a display device. The cross-sectional view which shows one aspect of the display device. The cross-sectional view which shows one aspect of the display device. The figure explaining the circuit structure of the semiconductor device. A diagram illustrating the configuration of the pixel circuit and a timing chart illustrating the operation of the pixel circuit. A block diagram and a circuit diagram illustrating a display device. A circuit diagram and a timing chart for explaining one aspect of the present invention. A graph and a circuit diagram for explaining one aspect of the present invention. A circuit diagram and a timing chart for explaining one aspect of the present invention. A circuit diagram and a timing chart for explaining one aspect of the present invention. Sectional drawing which shows an example of an input / output device. The figure explaining the display module. The figure explaining the electronic device.

Hereinafter, embodiments will be described with reference to the drawings. However, it is easily understood by those skilled in the art that the embodiments can be implemented in many different embodiments, and the embodiments and details can be variously changed without departing from the spirit and scope thereof. .. Therefore, the present invention is not construed as being limited to the description of the following embodiments.

Also, in the drawings, the size, layer thickness, or area may be exaggerated for clarity. Therefore, it is not necessarily limited to that scale. The drawings schematically show ideal examples, and are not limited to the shapes or values shown in the drawings.

Further, the ordinal numbers "first", "second", and "third" used in the present specification are added to avoid confusion of the components, and are not limited numerically. Addition.

Further, in the present specification, words and phrases indicating arrangements such as "above" and "below" are used for convenience in order to explain the positional relationship between the configurations with reference to the drawings. Further, the positional relationship between the configurations changes appropriately depending on the direction in which each configuration is depicted. Therefore, it is not limited to the words and phrases explained in the specification, and can be appropriately paraphrased according to the situation.

Further, in the present specification and the like, a transistor is an element having at least three terminals including a gate, a drain, and a source. Then, a channel region is provided between the drain (drain terminal, drain region or drain electrode) and the source (source terminal, source region or source electrode), and a current is passed through the drain, the channel region and the source. Can be done. In the present specification and the like, the channel region means a region in which a current mainly flows.

Further, the functions of the source and the drain may be switched when transistors having different polarities are adopted or when the direction of the current changes in the circuit operation. Therefore, in the present specification and the like, the terms source and drain can be used interchangeably.

Further, in the present specification and the like, "electrically connected" includes the case of being connected via "something having some kind of electrical action". Here, the "thing having some kind of electrical action" is not particularly limited as long as it enables the exchange of electric signals between the connection targets. For example, "things having some kind of electrical action" include electrodes, wirings, switching elements such as transistors, resistance elements, inductors, capacitors, and other elements having various functions.

Further, in the present specification and the like, "parallel" means a state in which two straight lines are arranged at an angle of −10 ° or more and 10 ° or less. Therefore, the case of −5 ° or more and 5 ° or less is also included. Further, "vertical" means a state in which two straight lines are arranged at an angle of 80 ° or more and 100 ° or less. Therefore, the case of 85 ° or more and 95 ° or less is also included.

Further, in the present specification and the like, the term "membrane" and the term "layer" can be interchanged with each other. For example, it may be possible to change the term "conductive layer" to the term "conductive layer". Or, for example, the term "insulating film" is referred to as "insulating layer".
It may be possible to change to the term.

Further, in the present specification and the like, unless otherwise specified, the off current means a drain current when the transistor is in an off state (also referred to as a non-conducting state or a cutoff state). Unless otherwise specified, the off state is the voltage V between the gate and source in an n-channel transistor.
A state in which gs is lower than the threshold voltage Vth, and in a p-channel transistor, a state in which the voltage Vgs between the gate and the source is higher than the threshold voltage Vth. For example, the off-current of an n-channel transistor means that the voltage Vgs between the gate and the source is the threshold voltage Vt.
It may refer to the drain current when it is lower than h.

The off current of the transistor may depend on Vgs. Therefore, the fact that the off current of the transistor is I or less may mean that there is a value of Vgs in which the off current of the transistor is I or less. The off-current of a transistor may refer to an off-current in a predetermined Vgs, an off-state in Vgs within a predetermined range, an off-state in Vgs in which a sufficiently reduced off-current is obtained, and the like.

As an example, the threshold voltage Vth is 0.5V, the drain current at Vgs is 0.5V is 1 × 10-9A, and the drain current at Vgs is 0.1V is 1 × 10-1.
3A, Vgs is -0.5V, drain current is 1x10-19A, Vg
Assume an n-channel transistor in which s is −0.8 V and the drain current is 1 × 10-22 A. Since the drain current of the transistor is 1 × 10 -19A or less in the range of Vgs of −0.5V or Vgs in the range of −0.5V to −0.8V, the off current of the transistor is 1 ×. It may be said that it is 10-19A or less. Since there are Vgs in which the drain current of the transistor is 1 × 10-22A or less, it may be said that the off current of the transistor is 1 × 10-22A or less.

Further, in the present specification and the like, the off-current of a transistor having a channel width W may be represented by a current value flowing per channel width W. Further, it may be represented by a current value flowing around a predetermined channel width (for example, 1 μm). In the latter case, the unit of off-current may be expressed in units having a current / length dimension (eg, A / μm).

The off current of the transistor may depend on the temperature. In the present specification, the off-current may represent an off-current at room temperature, 60 ° C., 85 ° C., 95 ° C., or 125 ° C., unless otherwise specified. Alternatively, the temperature used for the reliability required for the semiconductor device or the like including the transistor, or the temperature at which the semiconductor device or the like containing the transistor is used (for example, any one of 5 ° C to 35 ° C). ), May represent off-current. The off current of the transistor is I or less, which means room temperature, 60 ° C, 85 ° C, 9
5 ° C, 125 ° C, the temperature used for the reliability required for the semiconductor device including the transistor, or the temperature at which the semiconductor device including the transistor is used (for example, 5 ° C to 35 ° C). It may indicate that there is a value of Vgs in which the off-current of the transistor at (1 temperature) is equal to or less than I.

The off current of the transistor may depend on the voltage Vds between the drain and the source. In the present specification, the off-current has Vds of 0.1 V, 0.8 V, unless otherwise specified.
It may represent an off current at 1V, 1.2V, 1.8V, 2.5V, 3V, 3.3V, 10V, 12V, 16V, or 20V. Alternatively, it may represent Vds used in the reliability required for a semiconductor device or the like including the transistor, or an off current in Vds used in a semiconductor device or the like including the transistor. When the off current of the transistor is I or less, Vds is 0.1V, 0.8V, 1V, 1.
2V, 1.8V, 2.5V, 3V, 3.3V, 10V, 12V, 16V, 20V, Vds used in the reliability required for the semiconductor device including the transistor, or the semiconductor containing the transistor. It may indicate that there is a value of Vgs in which the off-current of the transistor in Vds, which is used in a device or the like, is I or less.

In the above description of the off-current, the drain may be read as the source. That is, the off current may refer to the current flowing through the source when the transistor is in the off state.

Further, in the present specification and the like, it may be described as a leak current in the same meaning as an off current. Further, in the present specification and the like, the off current may refer to, for example, the current flowing between the source and the drain when the transistor is in the off state.

Further, in the present specification and the like, the semiconductor impurities refer to other than the main components constituting the semiconductor film. For example, an element having a concentration of less than 0.1 atomic% is an impurity. The inclusion of impurities may cause DOS (Density of States) to be formed in the semiconductor, carrier mobility to be lowered, crystallinity to be lowered, and the like. When the semiconductor has an oxide semiconductor, the impurities that change the characteristics of the semiconductor include, for example, Group 1 elements, Group 2 elements, Group 14 elements, Group 15 elements, transition metals other than the main component, and the like. In particular, there are hydrogen (also contained in water), lithium, sodium, silicon, boron, phosphorus, carbon, nitrogen and the like. In the case of oxide semiconductors, oxygen deficiency may be formed by mixing impurities such as hydrogen. When the semiconductor has silicon, the impurities that change the characteristics of the semiconductor include, for example, Group 1 elements excluding oxygen and hydrogen, Group 2 elements, Group 13 elements, Group 15 elements and the like.

(Embodiment 1)
In the present embodiment, an example of a semiconductor device having a transistor and a method for manufacturing the semiconductor device will be described with reference to FIGS. 1 to 12.

<1-1. Configuration example of semiconductor device 1>
1 (A), (B), and (C) show an example of a semiconductor device having a transistor. The transistors shown in FIGS. 1A, 1B and 1C have a top gate structure.

1A is a top view of the transistor 150, FIG. 1B is a cross-sectional view between the alternate long and short dash lines X1-X2 of FIG. 1A, and FIG. 1C is FIG. 1A. It is sectional drawing between one-dot chain line Y1-Y2. In FIG. 1A, components such as the insulating film 110 are omitted for clarity. In addition, in the top view of the transistor, FIG. 1 (
Similar to A), some of the components may be omitted in the illustration. Also, alternate long and short dash line X1-X
The two directions may be referred to as the channel length (L) direction, and the alternate long and short dash line Y1-Y2 direction may be referred to as the channel width (W) direction.

The transistors 150 shown in FIGS. 1A, 1B and 1C have a conductive film 106 formed on the substrate 102, an insulating film 104 on the conductive film 106, and an oxide semiconductor film 108 on the insulating film 104.
The insulating film 110 on the oxide semiconductor film 108 and the oxide semiconductor film 112 on the insulating film 110.
And an oxide semiconductor film 108 and an insulating film 116 on the oxide semiconductor film 112.
Further, the oxide semiconductor film 108 has a channel region 108i on which the oxide semiconductor film 112 is superimposed.
The source region 108s provided in contact with the channel region 108i, and the channel region 10
It has a drain region 108d provided in contact with 8i, and the channel region 108i has a layer 108_2 and a layer 108_3 that is in contact with the top surface of layer 108_2 and covers the side surface of layer 108_2 in the channel width direction.

The source region 108s and the drain region 108d each have an impurity element. Examples of the impurity element include hydrogen, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, and noble gas. Typical examples of rare gas elements include helium, neon, argon, krypton, xenon and the like. Source area 108s and drain area 108d
However, the carrier density of the oxide semiconductor film can be increased by the configuration having the above-mentioned impurity element.

Further, the oxide semiconductor film 112 is electrically connected to the conductive film 106 via the insulating film 110, the layer 108_3, and the opening 143 provided in the insulating film 104. Therefore, the conductive film 1
The same potential is applied to 06 and the oxide semiconductor film 112. However, it is not limited to this.
Different potentials may be applied to the conductive film 106 and the oxide semiconductor film 112 without providing the opening 143.

The conductive film 106 has a function as a first gate electrode (also referred to as a bottom gate electrode), and the oxide semiconductor film 112 has a function as a second gate electrode (also referred to as a top gate electrode). .. Further, the insulating film 104 has a function as a first gate insulating film, and the insulating film 110 has a function as a second gate insulating film.

Further, the transistor 150 includes the insulating film 118 on the insulating film 116 and the insulating films 116 and 11.
8 and the conductive film 120a electrically connected to the source region 108s via the opening 141a provided in the layer 108_3, and the opening 141b provided in the insulating films 116, 118, and the layer 108_3. , Conductive film 120b electrically connected to the drain region 108d
And may have.

The transistor 150 may be, for example, low temperature polysilicon (LTPS (Low)).
It can be formed using a temperature (Temperature Poly-Silicon)) or a hydrogenated amorphous silicon (a—Si: H) manufacturing apparatus. Therefore, there is no need to make new capital investment, or new capital investment is extremely small.

Further, in the present specification and the like, the conductive film 120a has a function as a source electrode, and the conductive film 120b has a function as a drain electrode.

Defects (for example, oxygen deficiency) are likely to be formed due to damage in processing or contaminated by adhesion of impurities on or near the side surface of the channel region 108i in the channel width (W) direction of the oxide semiconductor film 108. .. Therefore, the channel area 1
Even if 08i is substantially true, the application of stress such as an electric field activates the side surface of the channel region 108i in the channel width (W) direction or its vicinity, resulting in low resistance (
It tends to be an n-type) region. Further, when the side surface of the channel region 108i in the channel width (W) direction or its vicinity is an n-type region, the n-type region serves as a carrier path, so that a parasitic channel may be formed.

Therefore, in the semiconductor device of one aspect of the present invention, the channel region 108i is formed in a laminated structure, and the side surface of the channel region 108i in the channel width (W) direction is covered with one layer of the laminated structure. With this configuration, it is possible to reduce the adhesion of defects or impurities on or near the side surface of the channel region 108i.

In addition, in FIGS. 1A, 1B, and 1C, the laminated structure of the channel region 108i is the layer 1.
The two-layer structure of 08_2 and layer 108_3 is used, but the structure is not limited to this. For example, FIG. 2 (A)
) (B) (C) may be a laminated structure as shown in (C).

2A is a top view of the transistor 150A, FIG. 2B is a cross-sectional view between the alternate long and short dash lines X1-X2 of FIG. 2A, and FIG. 2C is FIG. 2A. It is sectional drawing between one-dot chain line Y1-Y2.

The oxide semiconductor film 108 included in the transistor 150A is provided in contact with the channel region 108i on which the oxide semiconductor film 112 is superimposed and the channel region 108i.
It has 8s and a drain region 108d provided in contact with the channel region 108i.
Further, the channel region 108i is in contact with the layer 108_2 and the upper surface of the layer 108_2, and the layer 1
It has a layer 108_3 that covers the side surface of 08_2 in the channel width direction, and a layer 108_1 that is in contact with the lower surface of the layer 108_2.

As described above, the transistor 150A has a different structure of the oxide semiconductor film 108 included in the transistor 150 shown above. Other than that, the configuration is the same as that of the transistor 150, and the same effect is obtained.

The layer 108_1, the layer 108_2, and the layer 108_3 in the oxide semiconductor film 108 have at least one of the same elements. Therefore, interfacial scattering is unlikely to occur at the interface between the layer 108_1 and the layer 108_2, or the interface between the layer 108_2 and the layer 108_3. therefore,
Since the movement of the carrier is not hindered at the interface, the electric field effect mobility (may be simply referred to as mobility or μFE) of the transistor 150 and the transistor 150A becomes high.

It is preferable that the layers 108_1, 108_2, and 108_3 each have a metal oxide, and the metal oxide has at least indium (In) or zinc (Zn).

When the oxide semiconductor film has In, for example, carrier mobility (electron mobility) becomes high.
Further, when the oxide semiconductor film has Zn, crystallization of the oxide semiconductor film is likely to occur.

Further, when the oxide semiconductor film has the element M having a function as a stabilizer, for example, the energy gap (Eg) of the oxide semiconductor film becomes large. The oxide semiconductor film suitable for one aspect of the present invention has an energy gap of 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. As described above, by using the metal oxide having a large energy gap for the oxide semiconductor film 108, the off-current of the transistors 150 and 150A can be reduced. The element M is an element having a high binding energy with oxygen, and has a higher binding energy with oxygen than In.

Typical examples of the oxide semiconductor film suitable for the semiconductor device of one aspect of the present invention are InZ.
n oxide, In—M oxide, and In—M—Zn oxide can be used. Above all, In-
M-Zn oxide (M is aluminum (Al), gallium (Ga), yttrium (Y),
Or tin (Sn)) is preferably used. In particular, In-G where M is Ga.
It is preferable to use a—Zn oxide (hereinafter, may be referred to as IGZO).

When layer 108_2 has an In—M—Zn oxide, the atomic number ratio of In and M excluding Zn and oxygen is preferably greater than 25 atomic% for In and less than 75 atomic% for M, even more preferably. In is greater than 34 atomic% and M is less than 66 atomic%. In particular, it is preferable that the layer 108_2 has a region in which the atomic number ratio of In is equal to or higher than the atomic number ratio of M.

Further, since the layer 108_2 has a region in which the atomic number ratio of In is equal to or higher than the atomic number ratio of M, the electric field effect mobility of the transistor can be increased. Specifically, the transistor 1
The field effect mobility of the 50 and 150A can exceed 10 cm2 / Vs, and more preferably the field effect mobility of the transistors 150 and 150A can exceed 30 cm2 / Vs.

For example, a transistor having high field effect mobility can reduce the channel width. Therefore, by using the transistor in a scan line drive circuit (also referred to as a gate driver) that generates a gate signal or a demultiplexer connected to the output terminal of the shift register of the scan line drive circuit, the scan line drive circuit can be used. The size can be reduced, and a semiconductor device or a display device having a narrow frame width (also referred to as a narrow frame) can be provided. Alternatively, since the gate voltage can be reduced, the power consumption of the display device can be reduced.

Further, by increasing the electric field effect mobility of the transistor, the display device can be made high-definition. For example, 4k x 2k (horizontal pixel count = 3840 pixels, vertical pixel count = 216)
0 pixels) or 8k x 4k (horizontal pixel number = 7680 pixels, vertical pixel number = 4320)
It can be suitably used as a transistor in a pixel circuit or a drive circuit of a high-definition display device typified by a pixel).

On the other hand, when the layer 108_2 has a region in which the atomic number ratio of In is equal to or higher than the atomic number ratio of M, the energy gap (Eg) becomes small, so that the electrical characteristics of the transistor tend to fluctuate during light irradiation. However, in the semiconductor device of one aspect of the present invention, layer 108_
Layer 108_3 is formed on 2. Alternatively, layer 108_1 is formed on layer 108_1.

Further, the layer 108_1 and the layer 108_3 have a region in which the atomic number ratio of In is smaller than that of the layer 108_2. Therefore, Eg is larger than that of layer 108_2. Therefore, layer 10
8_2 and layer 108_3 are laminated, or layer 108_1, layer 108_2, and layer 1
By stacking 08_3, it is possible to increase the resistance of the transistor by the photonegative bias stress test.

When layers 108_1 and 108_3 have In—M—Zn oxide, the atomic number ratio of In and M excluding Zn and oxygen is less than 75 atomic% for In and 25 atom for M.
It is preferably larger than ic%, and more preferably In is less than 66 atomic%, M.
Is greater than 34 atomic%. In particular, it is preferable that the layer 108_1 and the layer 108_3 have a region in which the atomic number ratio of M is equal to or higher than the atomic number ratio of In.

It should be noted that the layers 108_1 and 108_3 may have the following effects when the element M has an atomic number ratio of In or more. (1) The energy gap becomes large. (2) The electron affinity becomes small. (3) Shield impurities from the outside. (4) Insulation is improved. again,
Since the element M is a metal element having a strong binding force with oxygen, oxygen deficiency is less likely to occur by having M at an atomic number ratio of In or higher.

Further, the number of atoms of the element M contained in the layers 108_1 and 108_3 is preferably equal to or larger than the number of atoms of the element M possessed by the layer 108_2. Typically, the atomic number ratio of the element M contained in the layers 108_1 and 108_3 is preferably 1.5 times or more, more preferably 2 times or more, as compared with the element M contained in the layer 108_2.

Further, the number of In atoms of the layer 108_2 is the In of the layers 108_1 and 108_3.
It is preferable that the number of atoms is equal to or greater than that of. Typically, the atomic number ratio of the element In contained in the layer 108_2 is preferably 1.5 times or more, more preferably 2 times or more, as compared with the element In contained in the layer 108_1 or the layer 108_3. At this time, the layer 108_2 is the transistor 1.
It can have a function as a channel region at 50 and 150A. Further, according to the configuration, the on-current is increased in the transistors 150 and 150A, and the effect of increasing the field effect mobility can be expected. In a transistor having high field effect mobility, the threshold voltage may have a negative electrical characteristic (also referred to as a normally-on characteristic). This is because electric charges are generated due to oxygen deficiency contained in the oxide semiconductor film of the transistor, and the resistance is lowered. When a transistor has a normally-on characteristic, various problems such as a tendency for malfunction to occur during operation or an increase in power consumption during non-operation occur. Therefore, the layer 108_2 has few impurities and defects (oxygen deficiency, etc.).
It is preferably CAAC-OS, which will be described later.

<1-2. Band structure>
Next, the band structure of the oxide semiconductor film in the transistor 150 shown in FIG. 1 and the transistor 150A shown in FIG. 2 and the insulating film in contact with the oxide semiconductor film will be described with reference to FIG.

FIG. 8A shows a band structure of the insulating film 104, the layer 108_2, the layer 108_3, and the insulating film 110 in the film thickness direction, and FIG. 8B shows the insulating film 104, the layer 108_1, and the layer 108_2.
It is a band structure in the film thickness direction of the layer 108_3 and the insulating film 110. The band structure is
For ease of understanding, the energy level (Ec) at the lower end of the conduction band of the insulating film 104, the layers 108_1, 108_2, 108_3, and the insulating film 110 is shown.

Further, here, a silicon oxide film is used as the insulating film 104 and the insulating film 110, and the layer 10 is used.
As 8_1, an oxide semiconductor film formed by using a metal oxide target of In: Ga: Zn = 1: 1: 1.2 is used, and as layer 108_1, the atomic number ratio of the metal element is set. Using an oxide semiconductor film formed using a metal oxide target of In: Ga: Zn = 4: 2: 4.1, the atomic number ratio of the metal element is set as layer 108_3 In: Ga: Zn = 1: 1.
: An oxide semiconductor film formed using the metal oxide target of 1.2 is used.

As shown in FIGS. 8A and 8B, in layers 108_1, 108_2, and 108_3, the energy at the lower end of the conduction band has no barrier and changes gently. In other words, it can be said that it changes continuously or joins continuously. Therefore, such an energy band is also called an embedded channel structure.

This is because the layer 108_1, the layer 108_2, and the layer 108_3 have an element in common, and the layer 108_
This is because the mixed layer is formed by the mutual movement of oxygen between 1 and the layer 108_2 and the layer 108_3. Further, in order to have such a band structure, the layer 108_1 and the layer 1 are required.
The laminated structure is such that impurities forming a defect level such as a trap center and a recombination center do not exist at the interface with 08_2 or the interface between 108_2 and the layer 108_3.

It should be noted that the continuous junction is not formed, and the interface between the layer 108_1 and the layer 108_2, or the layer 108
When impurities are mixed at the interface between _2 and layer 108_3, the continuity of the energy band is lost, and carriers are trapped or recombinated at the interface and disappear.

In order to form a continuous junction, it is preferable to provide a load lock chamber and use a multi-chamber type film forming apparatus (sputtering apparatus) to continuously stack the films without exposing them to the atmosphere. Each chamber in the sputtering device is for the oxide semiconductor film.
It is preferable to exhaust a high vacuum (up to about 5 × 10-7 Pa to 1 × 10-4 Pa) using an adsorption type vacuum pump such as a cryopump in order to remove water and the like as impurities as much as possible. Alternatively, it is preferable to combine a turbo molecular pump and a cold trap to prevent gas, particularly a gas having carbon or hydrogen, from flowing back from the exhaust system into the chamber.

With the configuration shown in FIGS. 8A and 8B, the layer 108_2 becomes a well, and the transistor 150 having the layer 108_2 and the layer 108_3, and the layer 108_1 and the layer 1
It can be seen that in the transistor 150A having 08_2 and layer 108_3, a channel region is formed in layer 108_2.

In the transistor 150, even if a trap level due to impurities or defects is formed in the vicinity of the interface between the layer 108_3 and the insulating film 110, the layer 108_3 is provided to form the layer 108_2 and the trap level. You can move away from the area. again,
In the transistor 150A, the vicinity of the interface between the layer 108_1 and the insulating film 104 and the layer 1
Even if a trap level due to impurities or defects is formed near the interface between 08_3 and the insulating film 110, the layers 108_1 and 108_3 are provided to keep the layer 108_2 and the region where the trap level is formed away from each other. be able to.

However, the energy level of the trap level is layer 108_2, which functions as a channel region.
When the energy level is lower than the energy level (Ec) at the lower end of the conduction band, electrons are more likely to be captured at the trap level. When electrons are captured and accumulated at the trap level, a negative fixed charge is generated on the insulating film surface, and the threshold voltage of the transistor shifts in the positive direction. Therefore, it is preferable that the energy level of the trap level is higher than the energy level (Ec) at the lower end of the conduction band of the layer 108_2. By doing so, it becomes difficult for electrons to accumulate at the trap level, it is possible to increase the on-current of the transistor, and it is possible to increase the field effect mobility. Further, it is suitable because the fluctuation of the threshold voltage of the transistor is reduced and the electric characteristics are stable.

Further, in order to prevent the layers 108_1 and 108_3 from functioning as a part of the channel region, it is preferable to use a material having a lower conductivity than the layer 108_2 for the layers 108_1 and 108_3. Therefore, the layers 108_1 and 108_3 can also be called oxide insulating films because of their physical characteristics and / or functions. Further, in layers 108_1 and 108_3, the electron affinity (difference between the vacuum level and the energy level at the lower end of the conduction band) is smaller than that in layer 108_2, and the energy level at the lower end of the conduction band is the energy level at the lower end of the conduction band of layer 108_2. It is preferable to use a material having a position and a difference (band offset). Further, in order to suppress the difference in the threshold voltage depending on the magnitude of the drain voltage, the energy level at the lower end of the conduction band of the layers 108_1 and 108_3 is the energy level at the lower end of the conduction band of the layer 108_2. It is preferable to apply a material closer to the vacuum level than 0.2 eV, preferably 0.5 eV or more and closer to the vacuum level.

With such a configuration, the layer 108_2 becomes the main current path in the channel region 108i. That is, the layer 108_2 has a function as a channel region, and the layer 10
8_1 and 108_3 have a function as an oxide insulating film. Also, layers 108_1 and 10
Since 8_3 is an oxide semiconductor film composed of one or more of the metal elements constituting the layer 108_2 on which the channel region is formed, the interface between the layer 108_1 and the layer 108_2, or the layer 1
At the interface between 08_2 and layer 108_3, interfacial scattering is unlikely to occur. Therefore, since the movement of the carrier is not hindered at the interface, the field effect mobility of the transistor is increased.

<1-3. Oxide semiconductor film that functions as a second gate electrode>
Next, the oxide semiconductor film that functions as the second gate electrode will be described. The oxide semiconductor film 112 that functions as the second gate electrode has a function of supplying oxygen to the insulating film 110. The oxide semiconductor film 112 has a function of supplying oxygen to the insulating film 110, whereby
The insulating film 110 has an excess oxygen region. The insulating film 110 has an excess oxygen region, so that the insulating film 110 has an excess oxygen region.
The excess oxygen can be supplied into the oxide semiconductor film 108, more specifically, the channel region 108i. Therefore, by compensating for the oxygen deficiency in the channel region 108i by excess oxygen, a highly reliable semiconductor device can be obtained.

In order to supply excess oxygen to the oxide semiconductor film 108, the oxide semiconductor film 10 is used.
Excess oxygen may be supplied to the insulating film 104 formed below the 8. Further, the insulating film 110 formed above the oxide semiconductor film 108 is configured to have excess oxygen, and by adding impurities to the source region 108s and the drain region 108d via the insulating film 110, the channel region 108i, After supplying excess oxygen to the source region 108s and the drain region 108d, the carrier density of the source region 108s and the drain region 108d can be selectively increased.

Further, the insulating film 116 has either one or both of nitrogen and hydrogen. Insulating film 1
By configuring 16 to have either or both of nitrogen and hydrogen, it is possible to supply either or both of nitrogen and hydrogen to the oxide semiconductor film 112.

The oxide semiconductor film 112 has a high carrier density by supplying oxygen to the insulating film 110 and then supplying either or both of nitrogen and hydrogen from the insulating film 116. In other words, the oxide semiconductor film 112 is an oxide conductor (OC: Oxide Cond).
It also has a function as an uctor). Therefore, the oxide semiconductor film 112 has a higher carrier density than the oxide semiconductor film 108, and can function as a second gate electrode.

Further, the source region 108s and the drain region 108d of the oxide semiconductor film 108
, And the oxide semiconductor film 112 may each have an element that forms an oxygen deficiency. Typical examples of the element forming the oxygen deficiency include hydrogen, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, chlorine, and noble gas. Typical examples of rare gas elements include helium, neon, argon, krypton, xenon and the like.

When the impurity element is added to the oxide semiconductor film, the bond between the metal element and oxygen in the oxide semiconductor film is broken, and an oxygen deficiency is formed. Alternatively, when the impurity element is added to the oxide semiconductor film, the oxygen bonded to the metal element in the oxide semiconductor film is combined with the impurity element, oxygen is desorbed from the metal element, and an oxygen deficiency is formed. To. As a result, the carrier density of the oxide semiconductor film is increased and the conductivity is increased.

As described above, in the semiconductor device of one aspect of the present invention, the insulating film that covers the side surface of the oxide semiconductor film that is the channel region and is formed above the channel region functions as a second gate electrode. The oxide semiconductor film contains excess oxygen. With such a configuration, a highly reliable semiconductor device can be provided.

<1-4. s-channel structure>
Next, the s-channel structure will be described.

As shown in FIG. 1C, the oxide semiconductor film 108 faces each of the conductive film 106 that functions as the first gate electrode and the oxide semiconductor film 112 that functions as the second gate electrode. It is located and sandwiched between a conductive film or an oxide semiconductor film that functions as two gate electrodes.

The length of the oxide semiconductor film 112 in the channel width (W) direction is the oxide semiconductor film 108.
The entire channel width (W) direction of the oxide semiconductor film 108 is covered with the oxide semiconductor film 112 via the insulating film 110, which is longer than the length in the channel width (W) direction of the oxide semiconductor film 108. Further, since the oxide semiconductor film 112 and the conductive film 106 are connected at the opening 143 provided in the insulating film 104, the layer 108_3, and the insulating film 110, the channel width (W) of the oxide semiconductor film 108 is increased.
One of the side surfaces in the direction faces the oxide semiconductor film 112 via the insulating film 110.

In other words, in the channel width (W) direction of the transistor 150, the conductive film 106 and the oxide semiconductor film 112 are connected at the insulating film 104, the layer 108_3, and the opening 143 provided in the insulating film 110, and the insulating film is formed. 104, layer 108_3, and insulating film 110
It is a configuration that surrounds the oxide semiconductor film 108 via the above.

By having such a configuration, the oxide semiconductor film 108 included in the transistor 150
Can be electrically surrounded by the electric fields of the conductive film 106 that functions as the first gate electrode and the oxide semiconductor film 112 that functions as the second gate electrode. Transistor 15
As shown in 0, the device structure of the transistor that electrically surrounds the oxide semiconductor film in which the channel region is formed by the electric fields of the first gate electrode and the second gate electrode is surrou.
It can be called an ned channel (s-channel) structure.

Since the transistor 150 has an s-channel structure, an electric field for inducing a channel by the conductive film 106 or the oxide semiconductor film 112 can be effectively applied to the oxide semiconductor film 108, so that the current of the transistor 150 can be applied. The drive capacity is improved, and it becomes possible to obtain high on-current characteristics. Further, since the on-current can be increased, the transistor 150 can be miniaturized. Further, since the transistor 150 has a structure surrounded by the conductive film 106 and the oxide semiconductor film 112, the mechanical strength of the transistor 150 can be increased.

In the channel width (W) direction of the transistor 150, an opening different from the opening 143 may be formed on the side surface side of the oxide semiconductor film 108 in which the opening 143 is not formed. Alternatively, the configuration may be such that the opening 143 is not provided. An example of such a case is shown in FIG. 7 (A).
(B) Shown in (C). 7 (A) is a top view of the transistor 170, FIG. 7 (B) is a cross-sectional view between the alternate long and short dash lines X1-X2 of FIG. 7 (A), and FIG. 7 (C) is FIG. 7 (A). It is sectional drawing between one-dot chain line Y1-Y2.

Further, as shown in the transistor 150, when the transistor has a pair of gate electrodes existing with a semiconductor film in between, a signal A is sent to one gate electrode and a fixed potential is attached to the other gate electrode. Vb may be given. Further, a signal A may be given to one gate electrode and a signal B may be given to the other gate electrode. In addition, a fixed potential Va is attached to one of the gate electrodes.
However, a fixed potential Vb may be applied to the other gate electrode.

The signal A is, for example, a signal for controlling a conduction state or a non-conduction state. The signal A may be a digital signal having two types of potentials, the potential V1 and the potential V2 (V1> V2). For example, the potential V1 can be set to a high power supply potential, and the potential V2 can be set to a low power supply potential. The signal A may be an analog signal.

The fixed potential Vb is, for example, the threshold voltage Vt seen from one of the gate electrodes of the transistor.
It is a potential for controlling hA. The fixed potential Vb may be the potential V1 or the potential V2. In this case, no special potential generation circuit is required. The fixed potential Vb may be a potential different from the potential V1 or the potential V2. By lowering the fixed potential Vb, the threshold voltage VthA may be increased. As a result, the drain current when the gate-source voltage Vgs is 0V may be reduced, and the leakage current of the circuit having the transistor may be reduced. For example, the fixed potential Vb may be lower than the low power supply potential. By increasing the fixed potential Vb, the threshold voltage VthA may be decreased. As a result, the drain current when the gate-source voltage Vgs is VDD may be improved, and the operating speed of the circuit having the transistor may be improved. For example, the fixed potential Vb may be higher than the low power supply potential.

The signal B is, for example, a signal for controlling a conduction state or a non-conduction state. The signal B may be a digital signal having two types of potentials, the potential V3 or the potential V4 (V3> V4). For example, the potential V3 can be set to a high power supply potential, and the potential V4 can be set to a low power supply potential. The signal B may be an analog signal.

When both the signal A and the signal B are digital signals, the signal B may be a signal having the same digital value as the signal A. In this case, it may be possible to improve the on-current of the transistor and improve the operating speed of the circuit having the transistor. At this time, the potentials V1 and V2 in the signal A may be different from the potentials V3 and V4 in the signal B. For example, when the gate insulating film corresponding to the gate to which the signal B is input is thicker than the gate insulating film corresponding to the gate to which the signal A is input, the potential amplitude (V3-V4) of the signal B is set to the signal A. It may be larger than the potential amplitude (V1-V2). By doing so, it may be possible to make the influence of the signal A and the influence of the signal B on the conduction state or the non-conduction state of the transistor to the same degree.

When both the signal A and the signal B are digital signals, the signal B may be a signal having a digital value different from that of the signal A. In this case, the transistor can be controlled separately by the signal A and the signal B, and a higher function may be realized. For example, the transistor is n
In the case of the channel type, the conduction state is obtained only when the signal A has the potential V1 and the signal B has the potential V3, or when the signal A has the potential V2 and the signal B has the potential V4. In the case of non-conduction state, one transistor may be able to realize functions such as NAND circuit and NOR circuit. Further, the signal B may be a signal for controlling the threshold voltage VthA. For example, the signal B may be a signal having different potentials depending on the period during which the circuit having the transistor is operating and the period during which the circuit is not operating. The signal B may be a signal having a different potential according to the operation mode of the circuit. In this case, signal B is signal A.
The potential may not switch as often.

When both signal A and signal B are analog signals, signal B is an analog signal having the same potential as signal A, an analog signal obtained by multiplying the potential of signal A by a constant value, or the potential of signal A added or subtracted by a constant value. It may be an analog signal or the like. In this case, the on-current of the transistor may be improved, and the operating speed of the circuit having the transistor may be improved. The signal B may be an analog signal different from the signal A. In this case, the transistor can be controlled separately by the signal A and the signal B, and a higher function may be realized.

The signal A may be a digital signal and the signal B may be an analog signal. Alternatively, the signal A may be an analog signal and the signal B may be a digital signal.

When a fixed potential is applied to both gate electrodes of a transistor, the transistor may be able to function as an element equivalent to a resistance element. For example, when the transistor is an n-channel type, the effective resistance of the transistor may be lowered (high) by increasing (lowering) the fixed potential Va or the fixed potential Vb. By increasing (lowering) both the fixed potential Va and the fixed potential Vb, an effective resistance lower (higher) than the effective resistance obtained by a transistor having only one gate may be obtained.

<1-5. Components of semiconductor devices>
Next, the details of the components of the semiconductor device shown in FIGS. 1A, 1B, and 1C will be described.

[substrate]
Various substrates can be used as the substrate 102, and the substrate 102 is not limited to a specific one. As an example of the substrate, a semiconductor substrate (for example, a single crystal substrate or a silicon substrate), SO
I substrate, glass substrate, quartz substrate, plastic substrate, metal substrate, stainless steel substrate, substrate with stainless steel still foil, tungsten substrate, substrate with tungsten foil, flexible substrate, laminated film, fibrous There is a paper containing the material of, or a base film. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, and soda lime glass. Examples of flexible substrates, laminated films, base films, etc. include the following. For example, there are plastics typified by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyether sulfone (PES). Alternatively, as an example, there is a synthetic resin such as acrylic. Alternatively, as an example, there are polypropylene, polyester, polyvinyl fluoride, polyvinyl chloride and the like. Alternatively, examples include polyamides, polyimides, aramids, epoxies, inorganic vapor deposition films, or papers. Especially semiconductor substrates,
By manufacturing a transistor using a single crystal substrate, an SOI substrate, or the like, it is possible to manufacture a transistor having a high current capacity and a small size with little variation in characteristics, size, shape, and the like. When a circuit is configured with such transistors, it is possible to reduce the power consumption of the circuit or increase the integration of the circuit.

Further, a flexible substrate may be used as the substrate 102, and a transistor may be formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate 102 and the transistor. The release layer can be used to separate a part or all of the semiconductor device from the substrate 102 and transfer it to another substrate. At that time, the transistor can be reprinted on a substrate having inferior heat resistance or a flexible substrate. For the above-mentioned peeling layer, for example, a structure in which an inorganic film of a tungsten film and a silicon oxide film is laminated, a structure in which an organic resin film such as polyimide is formed on a substrate, or the like can be used.

As an example of a substrate on which a transistor is reprinted, in addition to the above-mentioned substrate on which a transistor can be formed, a paper substrate, a cellophane substrate, an aramid film substrate, a polyimide film substrate, a stone substrate, a wood substrate, and a cloth substrate (natural fiber). (Silk, cotton, linen), synthetic fiber (nylon, polyurethane, polyester) or recycled fiber (acetate, cupra, rayon,
(Including recycled polyester), leather substrate, rubber substrate, etc. By using these substrates, it is possible to form a transistor having good characteristics, to form a transistor having low power consumption, to manufacture a device that is hard to break, to impart heat resistance, to reduce the weight, or to reduce the thickness.

[First gate insulating film]
The insulating film 104 includes a sputtering method, a CVD method, a vapor deposition method, and pulsed laser deposition (
It can be formed by appropriately using a PLD) method, a printing method, a coating method, or the like. In addition, the insulating film 104
For example, an oxide insulating film or a nitride insulating film can be formed as a single layer or laminated. In order to improve the interface characteristics with the oxide semiconductor film 108, it is preferable that at least the region of the insulating film 104 in contact with the oxide semiconductor film 108 is formed of the oxide insulating film. Further, by using an oxide insulating film that releases oxygen by heating as the insulating film 104, oxygen contained in the insulating film 104 can be transferred to the oxide semiconductor film 108 by heat treatment.

The thickness of the insulating film 104 can be 50 nm or more, 100 nm or more and 3000 nm or less, or 200 nm or more and 1000 nm or less. By thickening the insulating film 104, the amount of oxygen released from the insulating film 104 can be increased, the interface state at the interface between the insulating film 104 and the oxide semiconductor film 108, and the channel region of the oxide semiconductor film 108. 1
It is possible to reduce the oxygen deficiency contained in 08i.

As the insulating film 104, for example, silicon oxide, silicon nitride nitride, silicon nitride, silicon nitride, aluminum oxide, hafnium oxide, gallium oxide, Ga—Zn oxide, or the like may be used, and the insulating film 104 may be provided in a single layer or in a laminated manner. In the present embodiment, a laminated structure of a silicon nitride film and a silicon oxide film is used as the insulating film 104. As described above, by using the insulating film 104 as a laminated structure, using a silicon nitride film on the lower layer side and using a silicon oxide nitride film on the upper layer side, oxygen can be efficiently introduced into the oxide semiconductor film 108.

[Oxide semiconductor film]
As the oxide semiconductor film 108 and the oxide semiconductor film 112, the materials shown above can be used. Further, either one or both of the oxide semiconductor film 108 and the oxide semiconductor film 112 is formed of a metal oxide such as In—M—Zn oxide (M is Al, Ga, Y, or Sn). Further, In—Ga oxide and In—Zn oxide may be used as the oxide semiconductor film 108 and the oxide semiconductor film 112. In particular, when the oxide semiconductor film 108 and the oxide semiconductor film 112 are formed of a metal oxide made of the same constituent elements, it is preferable because the manufacturing cost can be reduced.

When the oxide semiconductor film 108 and the oxide semiconductor film 112 are In—M—Zn oxides, the atomic number ratio of In and M is 2 when the sum of In and M is 100 atomic%.
Higher than 5atomic%, M less than 75atomic%, or In is 34atomi
It is higher than c% and M is less than 66 atomic%.

The oxide semiconductor film 108 and the oxide semiconductor film 112 preferably have an energy gap of 2 eV or more, 2.5 eV or more, or 3 eV or more.

The thickness of the oxide semiconductor film 108 is 3 nm or more and 200 nm or less, preferably 3 nm or more and 1
It is 00 nm or less, more preferably 3 nm or more and 60 nm or less. The thickness of the oxide semiconductor film 112 is 5 nm or more and 500 nm or less, preferably 10 nm or more and 300 nm or less.
More preferably, it is 20 nm or more and 100 nm or less.

When the oxide semiconductor film 108 and the oxide semiconductor film 112 are In—M—Zn oxides, I
It is preferable that the atomic number ratio of the metal element of the sputtering target used for forming the n—M—Zn oxide is satisfied with In ≧ M and Zn ≧ M. As the atomic number ratio of the metal element of such a sputtering target, In: M: Zn = 1: 1: 1, In: M: Zn = 1:
1: 1.2, In: M: Zn = 2: 1: 1.5, In: M: Zn = 2: 1: 2.3, In
: M: Zn = 2: 1: 3, In: M: Zn = 3: 1: 2, In: M: Zn = 4: 2: 4.
1, In: M: Zn = 5: 1: 7 and the like are preferable. The oxide semiconductor film 108 to be formed is
, And the atomic number ratio of the oxide semiconductor film 112 may fluctuate by about plus or minus 40% of the atomic number ratio of the metal element contained in the above-mentioned sputtering target, respectively. for example,
When the atom number ratio of In: Ga: Zn = 4: 2: 4.1 is used as the sputtering target, the atom number ratio of the oxide semiconductor film formed is in the vicinity of In: Ga: Zn = 4: 2: 3. May be.

Further, when the oxide semiconductor film 108 and the oxide semiconductor film 112 contain silicon or carbon, which is one of the Group 14 elements, oxygen deficiency increases and the oxide semiconductor film 112 may become n-type. Therefore, in the oxide semiconductor film 108, particularly in the channel region 108i, the concentration of silicon or carbon (concentration obtained by secondary ion mass spectrometry) is set to 2 × 1018 atoms / c.
It can be m3 or less, or 2 × 1017 atoms / cm3 or less. As a result,
Transistors have electrical characteristics (also called normally-off characteristics) where the threshold voltage is positive.
).

Further, in the channel region 108i, the concentration of the alkali metal or alkaline earth metal obtained by the secondary ion mass spectrometry is 1 × 1018 atoms / cm3 or less, or 2
It can be × 1016 atoms / cm3 or less. Alkali metals and alkaline earth metals may generate carriers when combined with oxide semiconductors, which may increase the off-current of the transistor. Therefore, it is preferable to reduce the concentration of alkali metal or alkaline earth metal in the channel region 108i. As a result, the transistor has an electrical characteristic (also referred to as a normally-off characteristic) in which the threshold voltage becomes positive.

Further, when nitrogen is contained in the channel region 108i, electrons as carriers are generated, the carrier density increases, and the n-type may be formed. As a result, a transistor using an oxide semiconductor film containing nitrogen tends to have normally-on characteristics. Therefore, the channel region 1
In 08i, it is preferable that nitrogen is reduced as much as possible. For example, the nitrogen concentration obtained by the secondary ion mass spectrometry may be 5 × 1018 atoms / cm3 or less.

Further, by reducing the impurity elements in the channel region 108i, the carrier density of the oxide semiconductor film can be reduced. Therefore, in the channel region 108i,
The carrier density can be 1 × 1017 / cm3 or less, or 1 × 1015 / cm3 or less, or 1 × 1013 / cm3 or less, or 1 × 1011 / cm3 or less.

By using an oxide semiconductor film having a low impurity concentration and a low defect level density as the channel region 108i, a transistor having further excellent electrical characteristics can be manufactured.
Here, a low impurity concentration and a low defect level density (less oxygen deficiency) is referred to as high-purity intrinsic or substantially high-purity intrinsic. Alternatively, it is called true or substantially true. Oxide semiconductors with high-purity intrinsics or substantially high-purity intrinsics have few carrier sources, and therefore
It may be possible to reduce the carrier density. Therefore, the transistor in which the channel region is formed in the oxide semiconductor film tends to have an electric characteristic (also referred to as a normally-off characteristic) in which the threshold voltage is positive. Further, since the oxide semiconductor film having high purity intrinsicity or substantially high purity intrinsicity has a low defect level density, the trap level density may also be low.
Further, the oxide semiconductor film having high-purity intrinsicity or substantially high-purity intrinsicity can obtain the property that the off-current is remarkably small. Therefore, a transistor in which a channel region is formed in the oxide semiconductor film may be a highly reliable transistor with small fluctuations in electrical characteristics.

Further, the source region 108s and the drain region 108d have impurity elements. Since the source region 108s and the drain region 108d have impurity elements, the carrier density becomes high. Further, the oxide semiconductor film 112 is in contact with the insulating film 116. Oxide semiconductor film 1
When the 12 comes into contact with the insulating film 116, either one or both of hydrogen and nitrogen are added from the insulating film 116 to the oxide semiconductor film 112, so that the carrier density becomes high.

Further, either one or both of the oxide semiconductor film 108 and the oxide semiconductor film 112 may have a non-single crystal structure. The non-single crystal structure is, for example, CAAC-OS (CAx) described later.
is Defined Crystalline Oxide Semiconduct
or), includes a polycrystalline structure, a microcrystal structure described later, or an amorphous structure. In the non-single crystal structure, the amorphous structure has the highest defect level density, and CAAC-OS has the lowest defect level density.

A single-layer film in which the oxide semiconductor film 108 has two or more types of an amorphous structure region, a microcrystal structure region, a polycrystal structure region, a CAAC-OS region, and a single crystal structure region. Alternatively, it may have a structure in which these films are laminated. Further, a monolayer film in which the oxide semiconductor film 112 has two or more types of an amorphous structure region, a microcrystal structure region, a polycrystal structure region, a CAAC-OS region, and a single crystal structure region. Alternatively, it may have a structure in which these films are laminated.

In the oxide semiconductor film 108, the channel region 108i and the source region 108s
And the crystallinity from the drain region 108d may be different. Specifically, in the oxide semiconductor film 108, the source region 108s and the drain region 10 are more than the channel region 108i.
8d may have lower crystallinity. This is the source region 108s and the drain region 1
This is because when the impurity element is added to 08d, the source region 108s and the drain region 108d are damaged and the crystallinity is lowered.

[Second gate insulating film]
The insulating film 110 can be formed by a single layer or a laminate of an oxide insulating film or a nitride insulating film. In order to improve the interface characteristics with the oxide semiconductor film 108, it is preferable to form at least the region in contact with the oxide semiconductor film 108 in the insulating film 110 by using the oxide insulating film. As the insulating film 110, for example, silicon oxide, silicon oxide nitride, silicon nitride oxide, silicon nitride, aluminum oxide, hafnium oxide, gallium oxide or Ga.
-Zn oxide or the like may be used, and it can be provided in a single layer or in a laminated manner.

Further, by providing an insulating film having a blocking effect of oxygen, hydrogen, water, etc. as the insulating film 110, oxygen diffuses from the oxide semiconductor film 108 to the outside and hydrogen from the outside to the oxide semiconductor film 108. , Water, etc. can be prevented from entering. Examples of the insulating film having a blocking effect on oxygen, hydrogen, water, etc. include aluminum oxide, aluminum nitride, gallium oxide, and the like.
There are gallium nitride, yttrium oxide, yttrium oxide, hafnium oxide, hafnium oxide and the like.

Further, as the insulating film 110, a high-k material such as hafnium silicate (HfSiOx), nitrogen-added hafnium silicate (HfSixOyNz), nitrogen-added hafnium aluminate (HfAlxOyNz), hafnium oxide, and yttrium oxide is used. Can reduce the gate leak of the transistor.

Further, by using an oxide insulating film that releases oxygen by heating as the insulating film 110,
Oxygen contained in the insulating film 110 can be transferred to the oxide semiconductor film 108 by heat treatment.

The thickness of the insulating film 110 can be 5 nm or more and 400 nm or less, 5 nm or more and 300 nm or less, or 10 nm or more and 250 nm or less.

[First insulating film]
The insulating film 116 has either or both of nitrogen and hydrogen. Examples of the insulating film 116 include a nitride insulating film. The nitride insulating film includes silicon nitride,
It can be formed by using silicon nitride oxide, aluminum nitride, aluminum nitride or the like. The hydrogen concentration contained in the insulating film 116 is preferably 1 × 1022 atoms / cm3 or more. Further, the insulating film 116 is in contact with the oxide semiconductor film 112. Therefore, the hydrogen concentration in the oxide semiconductor film 112 in contact with the insulating film 116 becomes high, and the oxide semiconductor film 11
The carrier density of 2 can be increased.

[Second insulating film]
As the insulating film 118, an oxide insulating film or a nitride insulating film can be formed as a single layer or laminated. As the insulating film 118, for example, silicon oxide, silicon oxide nitride, silicon nitride oxide, silicon nitride, aluminum oxide, hafnium oxide, gallium oxide or G.
A—Zn oxide or the like may be used, and it can be provided in a single layer or in a laminated manner.

Further, the insulating film 118 is preferably a film that functions as a barrier film for hydrogen, water, etc. from the outside.

The thickness of the insulating film 118 is 30 nm or more and 500 nm or less, or 100 nm or more and 400 n.
It can be m or less.

[Conducting film]
The conductive films 120a and 120b can be formed by using a sputtering method, a vacuum vapor deposition method, a pulsed laser deposition (PLD) method, a thermal CVD method, or the like. In addition, the conductive film 120a
, 120b includes, for example, a metal element selected from aluminum, chromium, copper, tantalum, titanium, molybdenum, nickel, iron, cobalt, and tungsten, an alloy containing the above-mentioned metal element as a component, or the above-mentioned metal element. It can be formed by using a combined alloy or the like. Further, a metal element selected from any one or more of manganese and zirconium may be used. Further, the conductive films 120a and 120b may have a single-layer structure or a laminated structure having two or more layers. For example, a single-layer structure of an aluminum film containing silicon, a single-layer structure of a copper film containing manganese, a two-layer structure in which a titanium film is laminated on an aluminum film, a two-layer structure in which a titanium film is laminated on a titanium nitride film, and a nitrided structure. Two-layer structure in which a tungsten film is laminated on a titanium film, a two-layer structure in which a tungsten film is laminated on a tantalum nitride film or a tungsten nitride film, a two-layer structure in which a copper film is laminated on a copper film containing manganese, and a titanium film. A two-layer structure in which a copper film is laminated on a titanium film, a three-layer structure in which an aluminum film is laminated on the titanium film, and a titanium film is formed on the titanium film, and a copper film is laminated on a copper film containing manganese. Further, there is a three-layer structure for forming a copper film containing manganese on it. Further, an alloy film or a nitride film in which one or a plurality selected from titanium, tantalum, tungsten, molybdenum, chromium, neodymium, and scandium may be combined with aluminum may be used.

Further, the conductive films 120a and 120b are made of indium tin oxide (Indium Tin O).
xide: ITO), indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide, indium tin oxide containing silicon Things (In-Sn
-Si oxide: also referred to as ITSO) or the like, which has a translucent conductive material, can also be applied. Further, it is also possible to form a laminated structure of the conductive material having the translucency and the metal element.

The thickness of the conductive films 120a and 120b is 30 nm or more and 500 nm or less, or 10
It can be 0 nm or more and 400 nm or less.

<1-6. Configuration example 2 of semiconductor device>
Next, with respect to the configuration different from the semiconductor device shown in FIGS. 1 (A), (B) and (C), FIGS. 3 (A) and 3 (A) (
B) will be described with reference to (C).

3A is a top view of the transistor 150B, FIG. 3B is a cross-sectional view between the alternate long and short dash lines X1-X2 of FIG. 3A, and FIG. 3C is FIG. 3A. It is sectional drawing between one-dot chain line Y1-Y2.

The transistor 150B has a different configuration of the layer 108_3 from the transistor 150A shown above. Other than that, the configuration is the same as that of the transistor 150A, and the same effect is obtained.

The layer 108_3 included in the transistor 150B has the same shape as the oxide semiconductor film 112 functioning as the second gate electrode in the top view. That is, the layer 108_3 and the oxide semiconductor film 112 are formed by using the same mask. For example, layer 108_
After forming No. 3, the layer 108_3 can be processed using the same mask as the oxide semiconductor film 112 to form the structure of the transistor 150B.

<1-7. Configuration example of semiconductor device 3>
Next, FIGS. 1 (A) (B) (C), 2 (A) (B) (C), and 3 (A) (B) (C).
4 (A) (B) (C), FIGS. 5 (A) (B) with respect to the configuration different from the semiconductor device shown in).
(C) and FIGS. 6 (A), (B), and (C) will be described.

4A is a top view of the transistor 160, FIG. 4B is a cross-sectional view between the alternate long and short dash lines X1-X2 of FIG. 4A, and FIG. 4C is FIG. 4A. It is sectional drawing between one-dot chain line Y1-Y2. 5 (A) is a top view of the transistor 160A, and FIG. 5 (B) is FIG. 5 (A).
) Is a cross-sectional view between the alternate long and short dash lines X1-X2, FIG. 5 (C) is the alternate long and short dash line Y1-Y of FIG. 5 (A).
It is sectional drawing between two. FIG. 6A is a top view of the transistor 160B, and FIG. 6B is shown in FIG. 6B.
6 (A) is a cross-sectional view between the alternate long and short dash lines X1-X2 of FIG. 6 (A), and FIG. 6 (C) is a cross-sectional view of the alternate long and short dash line Y1-Y2 of FIG. 6 (A).

The transistors 160, 160A, and 160B are the transistors 150, respectively shown above.
It differs from 150A and 150B in that it has an insulating film 117. For other configurations,
It is the same as the transistor shown above, and has the same effect.

The insulating film 117 can be formed by using the material used for the insulating film 116. for example,
By forming the insulating film 117 on the oxide semiconductor film 112, impurities diffused into the insulating film 110 located below the oxide semiconductor film 112 and the channel region 108i during the addition treatment of the impurity element are suppressed. be able to.

As described above, in the transistor of one aspect of the present invention, the transistors described above may be appropriately combined and used.

<1-8. Manufacturing method of semiconductor device>
Next, an example of the method for manufacturing the transistor 150 shown in FIG. 1 will be described with reference to FIGS. 9 to 12. 9 to 12 are cross-sectional views in the channel length (L) direction and the channel width (W) direction for explaining the method for manufacturing the transistor 150.

First, the conductive film 106 is formed on the substrate 102. Next, the substrate 102 and the conductive film 106
An insulating film 104 is formed on the insulating film 104, and an oxide semiconductor film is formed on the insulating film 104. Then, the oxide semiconductor film is processed into an island shape to form the layer 108_2 (see FIG. 9A).

In the present embodiment, a tungsten film having a thickness of 100 nm is formed as the conductive film 106 by a sputtering method.

The insulating film 104 includes a sputtering method, a CVD method, a vapor deposition method, and pulsed laser deposition (
It can be formed by appropriately using a PLD) method, a printing method, a coating method, or the like. In the present embodiment, a PECVD apparatus is used as the insulating film 104 to form a silicon nitride film having a thickness of 400 nm and a silicon oxide film having a thickness of 50 nm.

Further, oxygen may be added to the insulating film 104 after the insulating film 104 is formed. Insulating film 10
Examples of oxygen added to 4 include oxygen radicals, oxygen atoms, oxygen atom ions, oxygen molecule ions and the like. Further, as the addition method, there are an ion doping method, an ion implantation method, a plasma treatment method and the like. Further, after forming a film that suppresses the desorption of oxygen on the insulating film, oxygen may be added to the insulating film 104 via the film.

As the above-mentioned film that suppresses the desorption of oxygen, a metal element selected from indium, zinc, gallium, tin, aluminum, chromium, tantalum, titanium, molybdenum, nickel, iron, cobalt, and tungsten, and the above-mentioned metal element are contained. Materials having conductivity such as alloys, alloys in which the above-mentioned metal elements are combined, metal nitrides having the above-mentioned metal elements, metal oxides having the above-mentioned metal elements, and metal nitride oxides having the above-mentioned metal elements. Can be formed using.

Further, when oxygen is added by plasma treatment, the amount of oxygen added to the insulating film 104 can be increased by exciting oxygen with microwaves to generate high-density oxygen plasma.

The layer 108_2 can be formed by a sputtering method, a coating method, a pulse laser vapor deposition method, a laser ablation method, a thermal CVD method, or the like. The layer 108_2 can be formed by forming a mask on the oxide semiconductor film by a lithography process and then etching a part of the oxide semiconductor film using the mask. Further, the element-separated layer 108_2 may be directly formed on the insulating film 104 by using a printing method.

When the oxide semiconductor film is formed by the sputtering method, an RF power supply device, an AC power supply device, a DC power supply device, or the like can be appropriately used as the power supply device for generating plasma. Further, as the sputtering gas for forming the oxide semiconductor film, a rare gas (typically argon), an oxygen, a rare gas, and a mixed gas of oxygen are appropriately used. In the case of a mixed gas of rare gas and oxygen, it is preferable to increase the gas ratio of oxygen to the rare gas.

When forming an oxide semiconductor film, for example, when a sputtering method is used, the substrate temperature is set to 150 ° C. or higher and 750 ° C. or lower, or 150 ° C. or higher and 450 ° C. or lower, or 200 ° C. or higher and 350 ° C. or lower. It is preferable to form a film because the crystallinity can be enhanced.

In this embodiment, a sputtering device is used as the layer 108_2, and an In—Ga—Zn metal oxide (In: Ga: Zn = 4: 2) is used as the sputtering target.
: 4.1 [atomic number ratio]) is used to form an oxide semiconductor film having a film thickness of 30 nm.

Further, after forming the layer 108_2, heat treatment may be performed to dehydrogenate or dehydrate the layer 108_2. The temperature of the heat treatment is typically 150 ° C. or higher and lower than the substrate strain point, or 250 ° C. or higher and 450 ° C. or lower, or 300 ° C. or higher and 450 ° C. or lower.

The heat treatment can be carried out in a rare gas such as helium, neon, argon, xenon, krypton, or an inert gas atmosphere containing nitrogen. Alternatively, after heating in an inert gas atmosphere, heating may be performed in an oxygen atmosphere. It is preferable that the inert atmosphere and the oxygen atmosphere do not contain hydrogen, water or the like. The processing time may be 3 minutes or more and 24 hours or less.

For the heat treatment, an electric furnace, an RTA device, or the like can be used. By using the RTA device, the heat treatment can be performed at a temperature equal to or higher than the strain point of the substrate for a short time. Therefore, the heat treatment time can be shortened.

By forming a film while heating the oxide semiconductor film, or by performing heat treatment after forming the oxide semiconductor film, the hydrogen concentration obtained by the secondary ion mass analysis method in the oxide semiconductor film is 5 × 1019 atoms. / Cm3 or less, or 1 × 1019 atoms / cm3 or less, 5 × 1018 atoms / cm3 or less, or 1 × 1018 atoms / cm3 or less,
Alternatively, it can be 5 × 1017 atoms / cm3 or less, or 1 × 1016 atoms / cm3 or less.

In the step of forming the layer 108_2, an oxide semiconductor film having a laminated structure is formed, and the oxide semiconductor film having the laminated structure is processed into an island shape to form the layer 108_1 and the layer 108_2. The transistor 150A described above can be formed.

Next, the insulating film 104, the layer 108_3, and the insulating film 110_0 are formed on the insulating film 108_2 (see FIG. 9B).

The layer 108_3 is formed so as to cover the side surface of the layer 108_2. In addition, layer 108_
As No. 3, it can be formed by the same material and the same method as the layer 108_2 described above.

In the present embodiment, a sputtering device is used as the layer 108_3, and an In—Ga—Zn metal oxide (In: Ga: Zn = 1: 3: 4 [In: Ga: Zn = 1: 3: 4] is used as the sputtering target.
Atomic number ratio]) is used to form an oxide semiconductor film having a film thickness of 5 nm.

Further, as the insulating film 110_0, a silicon oxide film or a silicon nitride film is used as PE.
It can be formed using the CVD method. In this case, it is preferable to use a sedimentary gas containing silicon and an oxidizing gas as the raw material gas. Typical examples of the sedimentary gas containing silicon include silane, disilane, trisilane, and fluorinated silane. Examples of the oxidizing gas include oxygen, ozone, nitrous oxide, nitrogen dioxide and the like.

Further, as the insulating film 110_0, the oxidizing gas with respect to the sedimentary gas is made larger than 20 times and 1
By using the PECVD method in which the pressure in the processing chamber is less than 100 times or 40 times or more and 80 times or less and the pressure in the processing chamber is less than 100 Pa or 50 Pa or less, a silicon oxide nitride film having a small amount of defects can be formed.

Further, as the insulating film 110_0, the substrate placed in the vacuum-exhausted processing chamber of the PECVD apparatus is held at 280 ° C. or higher and 400 ° C. or lower, and the raw material gas is introduced into the treatment chamber to increase the pressure in the treatment chamber at 20 Pa or higher and 250 Pa or higher. Hereinafter, it is more preferably 100 Pa or more and 250 Pa or less, and the insulating film 110_
As 0, a dense silicon oxide film or silicon oxynitride film can be formed.

Further, the insulating film 110_0 may be formed by using a plasma CVD method using microwaves. Microwave refers to the frequency range of 300 MHz to 300 GHz. In microwaves, the electron temperature is low and the electron energy is small. In addition, in the supplied power, the ratio used for accelerating electrons is small, it can be used for dissociation and ionization of more molecules, and it is possible to excite high-density plasma (high-density plasma). .. For this reason,
It is possible to form an insulating film 110_0 with less plasma damage to the surface to be filmed and deposits and less defects.

Further, the insulating film 110_0 can be formed by using a CVD method using an organic silane gas. As the organic silane gas, ethyl silicate (TEOS: chemical formula Si (OC2H5) 4)
), Tetramethylsilane (TMS: Chemical formula Si (CH3) 4), Tetramethylcyclotetrasiloxane (TMCTS), Octamethylcyclotetrasiloxane (OMCTS), Hexamethyldisilazane (HMDS), Triethoxysilane (SiH (OC2H5)). 3),
Silicon-containing compounds such as trisdimethylaminosilane (SiH (N (CH3) 2) 3) can be used. By using the CVD method using an organic silane gas, an insulating film 110_0 having a high covering property can be formed.

In the present embodiment, a PECVD apparatus is used as the insulating film 110_0 to form a silicon oxynitride film having a thickness of 100 nm.

Next, after forming a mask by lithography at a desired position on the insulating film 110_0,
By etching a part of the insulating film 110_0, the layer 108_3, and the insulating film 104, an opening 143 reaching the conductive film 106 is formed (see FIG. 9C).

As a method for forming the opening 143, a wet etching method and / or a dry etching method can be appropriately used. In this embodiment, a dry etching method is used.
The opening 143 is formed.

Next, the oxide semiconductor film 112_0 is formed on the insulating film 110_0 so as to cover the opening 143. At the time of forming the oxide semiconductor film 112_0, the oxide semiconductor film 112_
Oxygen is added into the insulating film 110_0 from 0 (see FIG. 9D).

In FIG. 9D, the oxygen added to the insulating film 110_0 is schematically represented by an arrow. Further, by forming the oxide semiconductor film 112_0 so as to cover the opening 143, the conductive film 106 and the oxide semiconductor film 112_0 are electrically connected.

As a method for forming the oxide semiconductor film 112_0, it is preferable to use a sputtering method and to form the oxide semiconductor film 112_0 in an atmosphere containing oxygen gas at the time of formation. By forming the oxide semiconductor film 112_0 in an atmosphere containing oxygen gas at the time of formation, oxygen can be suitably added to the insulating film 110_0.

In FIG. 9D, the oxygen added to the insulating film 110_0 is schematically represented by an arrow. Further, as the oxide semiconductor film 112_0, the same material as the layer 108_2 described above can be used.

In the present embodiment, a sputtering device is used as the oxide semiconductor film 112_0, and an In—Ga—Zn metal oxide (In: Ga: Zn =) is used as the sputtering target.
4: 2: 4.1 [atomic number ratio]) is used to form an oxide semiconductor film having a film thickness of 100 nm.

Next, the mask 1 is placed at a desired position on the oxide semiconductor film 112_0 by a lithography process.
40 is formed (see FIG. 10 (A)).

Next, etching is performed on the mask 140 to process the oxide semiconductor film 112_0, and then the mask 140 is removed to form an island-shaped oxide semiconductor film 112 (FIG. 10).
See (B)).

As the processing of the oxide semiconductor film 112_0, for example, a wet etching method or a dry etching method may be used. In the present embodiment, the oxide semiconductor film 112
The processing of _0 is performed by using a dry etching method.

Next, the impurity element 145 is added from the insulating film 110 and the oxide semiconductor film 112 (see FIG. 10C).

Examples of the method for adding the impurity element 145 include an ion doping method, an ion implantation method, and a plasma treatment method. In the case of the plasma treatment method, the impurity element can be added by generating plasma in a gas atmosphere containing the impurity element to be added and performing the plasma treatment. The devices for generating the plasma include a dry etching device, an ashing device, and the like.
A plasma CVD device, a high-density plasma CVD device, or the like can be used.

The raw material gas for the impurity element 145 is B2H6, PH3, CH4, N2, NH3.
, AlH3, AlCl3, SiH4, Si2H6, F2, HF, H2 and one or more of rare gases can be used. Alternatively, B2H6, PH3, N2, NH3 diluted with a noble gas,
One or more of AlH3, AlCl3, F2, HF, and H2 can be used. Rare gas by adding the impurity element 145 to the layer 108_2 and the oxide semiconductor film 112 using one or more of B2H6, PH3, N2, NH3, AlH3, AlCl3, F2, HF, and H2 diluted with a rare gas. , Hydrogen, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, and one or more of chlorine can be added to the layer 108_2 and the oxide semiconductor film 112.

Alternatively, after adding the noble gas, B2H6, PH3, CH4, N2, NH3, AlH3,
One or more of AlCl3, SiH4, Si2H6, F2, HF, and H2 may be added to the layer 108_2 and the oxide semiconductor film 112.

Alternatively, B2H6, PH3, CH4, N2, NH3, AlH3, AlCl3, SiH4
, Si2H6, F2, HF, and H2 may be added, and then the rare gas may be added to the layer 108_2 and the oxide semiconductor film 112.

The addition of the impurity element 145 may be controlled by appropriately setting injection conditions such as an acceleration voltage and a dose amount. For example, when adding argon by the ion implantation method, the acceleration voltage is 10 kV or more and 1
00kV or less, dose amount is 1 × 1013ions / cm2 or more and 1 × 1016ions / c
It may be m2 or less, for example, 1 × 1014ions / cm2. When adding phosphorus ions by the ion implantation method, the acceleration voltage is 30 kV and the dose amount is 1 × 1013.
It may be ion / cm2 or more and 5 × 1016 ions / cm2 or less, for example, 1 × 1.
It may be 015 ions / cm2.

Further, in the present embodiment, the configuration in which the impurity element 145 is added after the mask 140 is removed has been exemplified, but the present invention is not limited to this, and for example, the impurity element 145 is added while the mask 140 remains. Addition may be performed.

Further, in the present embodiment, as the impurity element 145, a doping device is used.
Phosphorus is added to the oxide semiconductor film 108 and the oxide semiconductor film 112. However, the present invention is not limited to this, and for example, the step of adding the impurity element 145 may not be performed.

By adding the impurity element 145, the source region 108s and the drain region 108d are formed in the layer 108_2 and the layer 108_3. Further, the oxide semiconductor film 112
A channel region 108i is formed in the layer 108_2 and the layer 108_3 that overlap with the layer 108_2. As a result, the oxide semiconductor film 108 of one aspect of the present invention is formed (see FIG. 10C).

As described above, the oxide semiconductor film 108 includes a channel region 108i on which the oxide semiconductor film 112 is superimposed, a source region 108s provided in contact with the channel region 108i, and a drain region 108d provided in contact with the channel region 108i. Has a channel area 108
i has a structure having a layer 108_2 and a layer 108_3 which is in contact with the upper surface of the layer 108_2 and covers the side surface of the layer 108_2 in the channel width direction.

In the case where the impurity element 145 is added to the surface of the oxide semiconductor film 108 without providing the insulating film 110, the source region 108s is caused by the damage caused by the addition of the impurity element 145.
And the crystallinity of the drain region 108d may decrease. On the other hand, the source area 108s
By adding the impurity element 145 via the insulating film 110 when forming the drain region 108d, damage at the time of adding the impurity element 145 is suppressed, and the source region 108s is suppressed.
And the decrease in crystallinity of the drain region 108d can be suppressed.

Next, the insulating film 116 is formed on the insulating film 110 and the oxide semiconductor film 112 (FIG. 11).
See (A)).

The insulating film 116 can be formed by selecting a material that can be used for the insulating film 116. In the present embodiment, a PECVD apparatus is used as the insulating film 116, and the insulating film 116 is used.
A silicon nitride film having a thickness of 100 nm is formed.

By using the silicon nitride film as the insulating film 116, hydrogen in the silicon nitride film can enter into the oxide semiconductor film 112 in contact with the insulating film 116, and the carrier density of the oxide semiconductor film 112 can be increased.

Next, the insulating film 118 is formed on the insulating film 116 (see FIG. 11B).

The insulating film 118 can be formed by selecting a material that can be used for the insulating film 118. In the present embodiment, a PECVD apparatus is used as the insulating film 118, and the thickness is 3
A silicon oxynitride film of 00 nm is formed.

Next, a mask is formed at a desired position of the insulating film 118 by lithography, and then the insulating film 118, the insulating film 116, the insulating film 110, and a part of the layer 108_3 are etched to reach the source region 108s. A portion 141a and an opening 141b reaching the drain region 108d are formed (see FIG. 11C).

As a method for etching the insulating film 118, the insulating film 116, the insulating film 110, and the layer 108_3, a wet etching method and / or a dry etching method can be used. In the present embodiment, the dry etching method is used, and the insulating film 118, the insulating film 116,
The insulating film 110 and the layer 108_3 are processed.

Next, the conductive film 120 is formed on the insulating film 118 so as to cover the openings 141a and 141b (see FIG. 12A).

The conductive film 120 can be formed by selecting a material that can be used for the conductive films 120a and 120b. In the present embodiment, a sputtering device is used as the conductive film 120, and a titanium film having a thickness of 50 nm, an aluminum film having a thickness of 400 nm, and a thickness of 100 are used.
A laminated film of a titanium film of nm is formed.

Next, after forming a mask at a desired position on the conductive film 120 by a lithography process, the mask is formed.
By etching a part of the conductive film 120, the conductive films 120a and 120b are formed (see FIG. 12B).

As a processing method for the conductive film 120, a wet etching method and / or a dry etching method can be used. In this embodiment, a dry etching method is used, and the conductive film 12 is used.
0 is processed to form conductive films 120a and 120b.

By the above steps, the transistor 150 shown in FIG. 1 can be manufactured.

The film (insulating film, oxide semiconductor film, conductive film, etc.) or layer constituting the transistor 150 can be a sputtering method, a chemical vapor deposition (CVD) method, a vacuum vapor deposition method, a pulse laser deposition (PLD) method, or an ALD. It can be formed by using the (atomic layer deposition) method. Alternatively, it can be formed by a coating method or a printing method. As a film forming method, a sputtering method and a plasma chemical vapor deposition (PECVD) method are typical, but a thermal CVD method may also be used. An example of the thermal CVD method is the MOCVD (organic metal chemical vapor deposition) method.

In the thermal CVD method, a film is formed by setting the inside of the chamber under atmospheric pressure or reduced pressure, sending the raw material gas and the oxidizing agent into the chamber at the same time, reacting them in the vicinity of the substrate or on the substrate, and depositing them on the substrate. As described above, since the thermal CVD method is a film forming method that does not generate plasma, it has an advantage that defects are not generated due to plasma damage.

Further, in the ALD method, the inside of the chamber is set to atmospheric pressure or reduced pressure, the raw material gas for the reaction is introduced and reacted in the chamber, and this is repeated to form a film. An inert gas (argon, nitrogen, etc.) may be introduced as a carrier gas together with the raw material gas. For example, two or more kinds of raw material gases may be supplied to the chamber in order. At that time, after the reaction of the first raw material gas, the inert gas is introduced and the second raw material gas is introduced so that a plurality of kinds of raw material gases are not mixed. Alternatively, instead of introducing the inert gas, the first raw material gas may be discharged by vacuum exhaust, and then the second raw material gas may be introduced. The first raw material gas adsorbs and reacts with the surface of the substrate to form a first layer, and the second raw material gas introduced later adsorbs and reacts with the second layer.
A thin film is formed by being laminated on the layer of. By repeating this process a plurality of times while controlling the gas introduction order until the desired thickness is reached, a thin film having excellent step covering property can be formed. Since the thickness of the thin film can be adjusted by the number of times the gas introduction is repeated, the film thickness can be precisely adjusted, which is suitable for manufacturing a fine FET.

A thermal CVD method such as the MOCVD method can form a film such as the conductive film, an insulating film, an oxide semiconductor film, or a metal oxide film described above, and for example, an In-Ga-Zn-O film is formed. In some cases, trimethylindium (In (CH3) 3), trimethylgallium (Ga (CH3))
) 3), and dimethylzinc is used (Zn (CH3) 2). The combination is not limited to these, and triethylgallium (Ga (C2H5) 3) can be used instead of trimethylgallium, and diethylzinc (Zn (C2H5) 2) can be used instead of dimethylzinc.

For example, when a hafnium oxide film is formed by a film forming apparatus using ALD, a liquid containing a solvent and a hafnium precursor (hafnium alkoxide or tetrakisdimethylamide hafnium (TDMAH, Hf [N (CH3) 2] 4)). And tetrakis (ethylmethylamide) hafnium amide such as hafnium) is vaporized, and two types of gas, ozone (O3), are used as an oxidizing agent.

For example, when an aluminum oxide film is formed by a film forming apparatus using ALD, a liquid containing a solvent and an aluminum precursor (trimethylaluminum (TMA, Al (CH3)).
Two types of gas, H2O, are used as the raw material gas obtained by vaporizing 3) and the like) and as an oxidizing agent. Other materials include tris (dimethylamide) aluminum, triisobutylaluminum,
There are aluminum tris (2,2,6,6-tetramethyl-3,5-heptane dionate) and the like.

For example, when a silicon oxide film is formed by a film forming apparatus using ALD, hexachlorodisilane is adsorbed on the surface to be deposited, and radicals of an oxidizing gas (O2, dinitrogen monoxide) are supplied to adsorb the adsorbed product. React with.

For example, when a tungsten film is formed by a film forming apparatus using ALD, WF6
Gas and B2H6 gas are sequentially introduced to form an initial tungsten film, and then a tungsten film is formed using WF6 gas and H2 gas. In addition, SiH4 gas may be used instead of B2H6 gas.

For example, an oxide semiconductor film, for example, In-Ga-Zn-, may be used by a film forming apparatus using ALD.
When forming an O film, an In—O layer is formed using In (CH3) 3 gas and O3 gas, and then a GaO layer is formed using Ga (CH3) 3 gas and O3 gas. And then Z
A ZnO layer is formed using n (CH3) 2 gas and O3 gas. The order of these layers is not limited to this example. Further, these gases may be used to form a mixed compound layer such as an In—Ga—O layer, an In—Zn—O layer, and a Ga—Zn—O layer. In addition, change to O3 gas and Ar
Although H2O gas obtained by bubbling water with an inert gas such as H2O gas may be used, it is preferable to use O3 gas containing no H.

As described above, the configuration and method shown in this embodiment can be used in appropriate combination with the configuration and method shown in other embodiments.

(Embodiment 2)
In the present embodiment, the structure of the oxide semiconductor and the like will be described with reference to FIGS. 13 to 17.

<2-1. Structure of oxide semiconductor>
Oxide semiconductors are divided into single crystal oxide semiconductors and other non-single crystal oxide semiconductors. As a non-single crystal oxide semiconductor, CAAC-OS (c-axis-aligne)
d crystalline oxide semiconductor), polycrystalline oxide semiconductor, nc-OS (nanocrystalline oxide semicon)
ductor), pseudo-amorphous oxide semiconductor (a-like OS: amorphous-)
Like oxide semiconductor) and amorphous oxide semiconductors.

From another viewpoint, the oxide semiconductor is divided into an amorphous oxide semiconductor and other crystalline oxide semiconductors. Crystalline oxide semiconductors include single crystal oxide semiconductors and CAAC.
-OS, polycrystalline oxide semiconductors, nc-OS and the like.

Amorphous structures are generally isotropic and have no anisotropic structure, the arrangement of atoms is not fixed in a metastable state, the bond angle is flexible, and short-range order is present but long-range order is present. It is said that it does not have.

From the opposite perspective, stable oxide semiconductors are completely amorphous.
orphous) It cannot be called an oxide semiconductor. Further, an oxide semiconductor that is not isotropic (for example, has a periodic structure in a minute region) cannot be called a completely amorphous oxide semiconductor.
On the other hand, a-like OS is not isotropic, but has an unstable structure having voids (also referred to as voids). In terms of instability, the a-like OS is physically close to an amorphous oxide semiconductor.

<2-2. CAAC-OS>
First, CAAC-OS will be described.

CAAC-OS is a kind of oxide semiconductor having a plurality of c-axis oriented crystal portions (also referred to as pellets).

A case where CAAC-OS is analyzed by X-ray diffraction (XRD: X-Ray Diffraction) will be described. For example, InGaZnO4 classified into the space group R-3m.
When the structure analysis of CAAC-OS having the above crystals by the out-of-plane method is performed, a peak appears in the diffraction angle (2θ) near 31 ° as shown in FIG. 13 (A). Since this peak belongs to the (009) plane of the crystal of InGaZnO4, CAAC-OS
Then, it can be confirmed that the crystal has c-axis orientation and the c-axis is oriented in a direction substantially perpendicular to the surface (also referred to as the formed surface) forming the CAAC-OS film or the upper surface. 2θ is 31
In addition to the peak in the vicinity of °, a peak may appear in the vicinity of 2θ at 36 °. 2θ is 36 °
The peaks in the vicinity are due to the crystal structure classified in the space group Fd-3m. Therefore, CAA
It is preferable that C-OS does not show the peak.

On the other hand, in-pl in which X-rays are incident on CAAC-OS from a direction parallel to the surface to be formed.
When the structure analysis is performed by the ane method, a peak appears in the vicinity of 2θ at 56 °. This peak is
It is attributed to the (110) plane of the crystal of InGaZnO4. Then, 2θ is fixed in the vicinity of 56 °, and analysis is performed while rotating the sample with the normal vector of the sample surface as the axis (φ axis) (φ scan).
However, no clear peak appears as shown in FIG. 13 (B). On the other hand, single crystal InGa
When 2θ is fixed in the vicinity of 56 ° and φ-scanned with respect to ZnO4, six peaks attributed to the crystal plane equivalent to the (110) plane are observed as shown in FIG. 13 (C). therefore,
From the structural analysis using XRD, it can be confirmed that the orientation of the a-axis and the b-axis of CAAC-OS is irregular.

Next, the CAAC-OS analyzed by electron diffraction will be described. For example, InGa
When an electron beam having a probe diameter of 300 nm is incident on CAAC-OS having a ZnO4 crystal in parallel with the surface to be formed of CAAC-OS, a diffraction pattern as shown in FIG. 13 (D) is formed.
Also called selected area electron diffraction pattern. ) May appear. This diffraction pattern includes I
A spot due to the (009) plane of the crystal of nGaZnO4 is included. Therefore, it can be seen from the electron diffraction that the pellets contained in CAAC-OS have c-axis orientation and the c-axis is oriented substantially perpendicular to the surface to be formed or the upper surface. On the other hand, the diffraction pattern when an electron beam having a probe diameter of 300 nm is incident on the same sample perpendicularly to the sample surface is shown in FIG. 13 (E).
). From FIG. 13 (E), a ring-shaped diffraction pattern is confirmed. Therefore, it can be seen that the a-axis and b-axis of the pellets contained in CAAC-OS do not have orientation even by electron diffraction using an electron beam having a probe diameter of 300 nm. It is considered that the first ring in FIG. 13 (E) is caused by the (010) plane and the (100) plane of the crystal of InGaZnO4. Further, it is considered that the second ring in FIG. 13 (E) is caused by the (110) plane or the like.

In addition, a transmission electron microscope (TEM: Transmission Electron M)
By observing a composite analysis image (also referred to as a high-resolution TEM image) of a bright-field image of CAAC-OS and a diffraction pattern by icroscopy), a plurality of pellets can be confirmed. On the other hand, even in a high-resolution TEM image, the boundary between pellets, that is, the grain boundary (also referred to as grain boundary) may not be clearly confirmed. Therefore, CAA
It can be said that C-OS is unlikely to cause a decrease in electron mobility due to grain boundaries.

FIG. 14A shows a high-resolution TEM image of a cross section of CAAC-OS observed from a direction substantially parallel to the sample surface. For observation of high-resolution TEM images, spherical aberration correction (Spherical A)
The variation (selector) function was used. A high-resolution TEM image using the spherical aberration correction function is particularly referred to as a Cs-corrected high-resolution TEM image. The Cs-corrected high-resolution TEM image can be observed, for example, with an atomic resolution analysis electron microscope JEM-ARM200F manufactured by JEOL Ltd.

From FIG. 14 (A), pellets, which are regions where metal atoms are arranged in layers, can be confirmed. It can be seen that the size of one pellet is 1 nm or more and 3 nm or more. Therefore, pellets can also be referred to as nanocrystals (nc: nanocrystals). In addition, CAAC-OS can be used as CANC (C-Axis Aligned na).
It can also be called an oxide semiconductor having nocrystals). The pellet is CAA
The C-OS film reflects the unevenness of the surface to be formed or the upper surface, and is parallel to the surface to be formed or the upper surface of CAAC-OS.

Further, in FIGS. 14 (B) and 14 (C), CAA observed from a direction substantially perpendicular to the sample surface.
A Cs-corrected high-resolution TEM image of the plane of the C-OS is shown. 14 (D) and 14 (E) are images obtained by image-processing FIGS. 14 (B) and 14 (C), respectively. The method of image processing will be described below. First, FIG. 14 (B) is obtained by performing a fast Fourier transform (FFT: Fast).
An FFT image is acquired by performing a Fourier Transform) process. Next, in the acquired FFT image, mask processing is performed to leave a range between 2.8 nm-1 and 5.0 nm-1 with respect to the origin. Next, the masked FFT image is subjected to the inverse fast Fourier transform (IFFT).
: Inverse Fast Fourier Transform) The image processed image is acquired by the processing. The image thus obtained is called an FFT filtering image. FFT
The filtering image is an image obtained by extracting a periodic component from a Cs-corrected high-resolution TEM image, and shows a grid array.

In FIG. 14 (D), the disordered portion of the lattice arrangement is shown by a broken line. The area surrounded by the broken line is one pellet. The part indicated by the broken line is the connecting portion between the pellets. Since the broken line has a hexagonal shape, it can be seen that the pellet has a hexagonal shape. The shape of the pellet is not limited to the regular hexagonal shape, and is often a non-regular hexagonal shape.

In FIG. 14 (E), a dotted line indicates a portion where the orientation of the grid arrangement changes between the region where the grid arrangement is aligned and the region where another grid arrangement is aligned, and the change in the orientation of the grid arrangement is shown. It is shown by a broken line. A clear grain boundary cannot be confirmed even in the vicinity of the dotted line. A distorted hexagon can be formed by connecting the surrounding grid points around the grid points near the dotted line. That is, it can be seen that the formation of grain boundaries is suppressed by distorting the lattice arrangement. This is CAAC-OS
It is considered that the strain can be tolerated because the bond distance between the atoms is not dense in the ab plane direction and the bond distance between the atoms changes due to the substitution of the metal element.

As shown above, CAAC-OS has a c-axis orientation and has a distorted crystal structure in which a plurality of pellets (nanocrystals) are connected in the ab plane direction. Therefore, C
AAC-OS is used as CAA crystal (c-axis-aligned a-b-p).
It can also be referred to as a lane-anchored crystal).

CAAC-OS is a highly crystalline oxide semiconductor. The crystallinity of oxide semiconductors may deteriorate due to the inclusion of impurities or the formation of defects, so the opposite view is CAAC-O.
It can be said that S is an oxide semiconductor having few impurities and defects (oxygen deficiency, etc.).

Impurities are elements other than the main components of oxide semiconductors, such as hydrogen, carbon, silicon, and transition metal elements. For example, an element such as silicon, which has a stronger bond with oxygen than a metal element constituting an oxide semiconductor, deprives the oxide semiconductor of oxygen, disturbs the atomic arrangement of the oxide semiconductor, and lowers the crystallinity. It becomes a factor. Also, heavy metals such as iron and nickel, argon,
Since carbon dioxide and the like have a large atomic radius (or molecular radius), they disturb the atomic arrangement of the oxide semiconductor and cause a decrease in crystallinity.

When an oxide semiconductor has impurities or defects, its characteristics may fluctuate due to light, heat, or the like. For example, impurities contained in an oxide semiconductor may be a carrier trap or a carrier generation source. For example, oxygen deficiency in an oxide semiconductor may become a carrier trap or a carrier generation source by capturing hydrogen.

CAAC-OS, which has few impurities and oxygen deficiency, is an oxide semiconductor having a low carrier density. Specifically, oxides having a carrier density of less than 8 × 1011 / cm3, preferably less than 1 × 1011 / cm3, more preferably less than 1 × 1010 / cm3, and a carrier density of 1 × 10-9 / cm3 or more. It can be a semiconductor. Such oxide semiconductors are referred to as high-purity intrinsic or substantially high-purity intrinsic oxide semiconductors. CAAC-OS has a low impurity concentration and a low defect level density. That is, it can be said that it is an oxide semiconductor having stable characteristics.

<2-3. nc-OS>
Next, the nc-OS will be described.

The case where the nc-OS is analyzed by XRD will be described. For example, when structural analysis is performed on nc-OS by the out-of-plane method, a peak indicating orientation does not appear. That is, the crystals of nc-OS have no orientation.

Further, for example, nc-OS having a crystal of InGaZnO4 is sliced and the thickness is 34n.
When an electron beam having a probe diameter of 50 nm is incident on the region of m in parallel with the surface to be formed, FIG.
A ring-shaped diffraction pattern (nanobeam electron diffraction pattern) as shown in 5 (A) is observed. In addition, the diffraction pattern when an electron beam with a probe diameter of 1 nm is incident on the same sample (
The nanobeam electron diffraction pattern) is shown in FIG. 15 (B). From FIG. 15B, a plurality of spots are observed in the ring-shaped region. Therefore, the probe diameter of nc-OS is 50 nm.
The order is not confirmed by injecting an electron beam of 1 nm, but the order is confirmed by injecting an electron beam having a probe diameter of 1 nm.

Further, when an electron beam having a probe diameter of 1 nm is incident on a region having a thickness of less than 10 nm, an electron diffraction pattern in which spots are arranged in a substantially regular hexagonal shape is observed as shown in FIG. 15 (C). May occur. Therefore, it can be seen that the nc-OS has a highly ordered region, that is, a crystal in the range of the thickness of less than 10 nm. Since the crystals are oriented in various directions, there are some regions where regular electron diffraction patterns are not observed.

FIG. 15D shows a Cs-corrected high-resolution TEM image of the cross section of the nc-OS observed from a direction substantially parallel to the surface to be formed. The nc-OS has a region in which a crystal portion can be confirmed, such as a portion indicated by an auxiliary line, and a region in which a clear crystal portion cannot be confirmed in a high-resolution TEM image. The crystal portion contained in nc-OS has a size of 1 nm or more and 10 nm or less, and in particular, it often has a size of 1 nm or more and 3 nm or less. A microcrystalline oxide semiconductor (fine) is an oxide semiconductor having a crystal portion larger than 10 nm and 100 nm or less.
It may be called a crystalline oxide semiconductor). In the nc-OS, for example, the crystal grain boundaries may not be clearly confirmed in a high-resolution TEM image. It should be noted that the nanocrystals may have the same origin as the pellets in CAAC-OS. Therefore, in the following, the crystal portion of nc-OS may be referred to as a pellet.

As described above, the nc-OS has periodicity in the atomic arrangement in a minute region (for example, a region of 1 nm or more and 10 nm or less, particularly a region of 1 nm or more and 3 nm or less). Also, nc-OS
Does not show regularity in crystal orientation between different pellets. Therefore, no orientation is observed in the entire film. Therefore, the nc-OS may be indistinguishable from the a-like OS and the amorphous oxide semiconductor depending on the analysis method.

Since the crystal orientation is not regular among the pellets (nanocrystals), the nc-OS is an oxide semiconductor having RANC (Random Aligned nanocrystals) or an oxide having NANC (Non-Aligned nanocrystals). It can also be called a semiconductor.

The nc-OS is an oxide semiconductor having higher regularity than the amorphous oxide semiconductor. Therefore, the defect level density of nc-OS is lower than that of a-like OS and amorphous oxide semiconductors. However, in nc-OS, there is no regularity in crystal orientation between different pellets. Therefore, the defect level density of nc-OS is higher than that of CAAC-OS.

<2-4. a-like OS>
The a-like OS is an oxide semiconductor having a structure between nc-OS and an amorphous oxide semiconductor.

FIG. 16 shows a high-resolution cross-sectional TEM image of the a-like OS. Here, FIG. 16 (A)
Is a high-resolution cross-sectional TEM image of the a-like OS at the start of electron irradiation. FIG. 16 (
B) is a high-resolution cross-sectional TEM image of a-like OS after electron (e-) irradiation of 4.3 × 108 e− / nm2. From FIG. 16 (A) and FIG. 16 (B), a-like O
It can be seen that in S, a striped bright region extending in the vertical direction is observed from the start of electron irradiation. It can also be seen that the shape of the bright region changes after electron irradiation. The bright region is presumed to be a void or a low density region.

Due to the presence of voids, the a-like OS has an unstable structure. In the following, a-lik
Since it is shown that eOS has an unstable structure as compared with CAAC-OS and nc-OS, the change in structure due to electron irradiation is shown.

Prepare a-like OS, nc-OS and CAAC-OS as samples. Both samples are In-Ga-Zn oxides.

First, a high-resolution cross-sectional TEM image of each sample is acquired. Due to the high resolution cross-sectional TEM image, each sample has a crystal part.

The unit cell of the crystal of InGaZnO4 has three In—O layers, and Ga—Zn also has three layers.
It is known that a total of 9 layers having 6 −O layers are stacked in a layered manner in the c-axis direction. The spacing between these adjacent layers is about the same as the grid plane spacing (also referred to as d value) of the (009) plane, and the value is determined to be 0.29 nm from the crystal structure analysis. therefore,
In the following, InGaZ indicates that the spacing between the plaids is 0.28 nm or more and 0.30 nm or less.
It was regarded as the crystal part of no4. The plaids correspond to the ab planes of the InGaZnO4 crystal.

FIG. 17 is an example of investigating the average size of the crystal portions (22 to 30 locations) of each sample. The length of the above-mentioned plaid is defined as the size of the crystal portion. From FIG. 17, a-lik
It can be seen that in the eOS, the crystal portion becomes larger according to the cumulative irradiation amount of electrons related to the acquisition of the TEM image. From FIG. 17, the crystal portion (also referred to as an initial nucleus) having a size of about 1.2 nm at the initial stage of TEM observation has a cumulative irradiation amount of electrons (e−) of 4.2 × 108e.
It can be seen that at − / nm2, it has grown to a size of about 1.9 nm. On the other hand, n
In c-OS and CAAC-OS, the cumulative dose of electrons is 4.2 × 10 from the start of electron irradiation.
It can be seen that there is no change in the size of the crystal portion in the range up to 8e− / nm2. FIG. 17
From this, it can be seen that the sizes of the crystal portions of nc-OS and CAAC-OS are about 1.3 nm and about 1.8 nm, respectively, regardless of the cumulative irradiation amount of electrons. A Hitachi transmission electron microscope H-9000NAR was used for electron beam irradiation and TEM observation. The electron beam irradiation conditions were an acceleration voltage of 300 kV, a current density of 6.7 × 105 e− / (nm2 · s), and a diameter of the irradiation region of 230 nm.

As described above, in the a-like OS, growth of the crystal portion may be observed by electron irradiation. On the other hand, in nc-OS and CAAC-OS, almost no growth of the crystal portion due to electron irradiation is observed. That is, it can be seen that the a-like OS has an unstable structure as compared with the nc-OS and the CAAC-OS.

Further, since it has a void, the a-like OS has a structure having a lower density than that of nc-OS and CAAC-OS. Specifically, the density of a-like OS is 78.6% or more and less than 92.3% of the density of a single crystal having the same composition. Also, the density of nc-OS and CAA
The density of C-OS is 92.3% or more and less than 100% of the density of a single crystal having the same composition. It is difficult to form an oxide semiconductor having a density of less than 78% of a single crystal.

For example, in an oxide semiconductor satisfying In: Ga: Zn = 1: 1: 1 [atomic number ratio],
The density of the single crystal InGaZnO4 having a rhombohedral crystal structure is 6.357 g / cm3. Therefore, for example, in an oxide semiconductor satisfying In: Ga: Zn = 1: 1: 1 [atomic number ratio], the density of a-like OS is 5.0 g / cm3 or more and less than 5.9 g / cm3. Further, for example, in an oxide semiconductor satisfying In: Ga: Zn = 1: 1: 1 [atomic number ratio], the density of nc-OS and the density of CAAC-OS are 5.9 g / cm3 or more and 6.3 g / cm.
It will be less than 3.

When a single crystal having the same composition does not exist, the density corresponding to the single crystal in a desired composition can be estimated by combining single crystals having different compositions at an arbitrary ratio.
The density corresponding to a single crystal having a desired composition may be estimated by using a weighted average with respect to the ratio of combining single crystals having different compositions. However, it is preferable to estimate the density by combining as few types of single crystals as possible.

As described above, oxide semiconductors have various structures, and each has various characteristics.
The oxide semiconductor may be, for example, an amorphous oxide semiconductor, a-like OS, nc-OS.
, CAAC-OS may be a laminated film having two or more kinds.

As described above, the configuration shown in this embodiment can be used in combination with the configurations shown in other embodiments or other examples as appropriate.

(Embodiment 3)
In the present embodiment, an example of the display device having the transistor exemplified in the previous embodiment will be described below with reference to FIGS. 18 to 20.

FIG. 18 is a top view showing an example of the display device. The display device 700 shown in FIG. 18 is the first display device 700.
The pixel unit 702 provided on the substrate 701, the source driver circuit unit 704 and the gate driver circuit unit 706 provided on the first substrate 701, the pixel unit 702, the source driver circuit unit 704, and the gate driver circuit unit. It has a sealing material 712 arranged so as to surround the 706, and a second substrate 705 provided so as to face the first substrate 701. note that,
The first substrate 701 and the second substrate 705 are sealed with a sealing material 712. That is, the pixel unit 702, the source driver circuit unit 704, and the gate driver circuit unit 706 are sealed by the first substrate 701, the sealing material 712, and the second substrate 705. Although not shown in FIG. 18, a display element is provided between the first substrate 701 and the second substrate 705.

Further, the display device 700 has a pixel unit 702, a source driver circuit unit 704, a gate driver circuit unit 706, and a gate driver circuit unit in a region different from the region surrounded by the sealing material 712 on the first substrate 701. An FPC terminal portion 708 (FPC: Flexible printed circuit board), which is electrically connected to each of the 706, is provided. Further, the FPC 716 is connected to the FPC terminal unit 708, and various signals and the like are supplied to the pixel unit 702, the source driver circuit unit 704, and the gate driver circuit unit 706 by the FPC 716. Further, a signal line 710 is connected to each of the pixel unit 702, the source driver circuit unit 704, the gate driver circuit unit 706, and the FPC terminal unit 708. FPC
Various signals and the like supplied by the 716 are given to the pixel unit 702, the source driver circuit unit 704, the gate driver circuit unit 706, and the FPC terminal unit 708 via the signal line 710.

Further, the display device 700 may be provided with a plurality of gate driver circuit units 706. Further, the display device 700 shows an example in which the source driver circuit unit 704 and the gate driver circuit unit 706 are formed on the same first substrate 701 as the pixel unit 702, but the present invention is not limited to this configuration. For example, only the gate driver circuit unit 706 may be formed on the first substrate 701, or only the source driver circuit unit 704 may be formed on the first substrate 701. In this case, a substrate on which a source driver circuit, a gate driver circuit, or the like is formed (for example, a drive circuit board formed of a single crystal semiconductor film or a polycrystalline semiconductor film) may be mounted on the first substrate 701. .. The method for connecting the separately formed drive circuit board is not particularly limited, and a COG (Chip On Glass) method, a wire bonding method, or the like can be used.

Further, the pixel unit 702, the source driver circuit unit 704, and the gate driver circuit unit 706 of the display device 700 have a plurality of transistors, and the transistor which is the semiconductor device of one aspect of the present invention can be applied. ..

Further, the display device 700 can have various elements. As an example of the element,
For example, electroluminescence (EL) elements (EL elements containing organic and inorganic substances, organic EL elements, inorganic EL elements, LEDs, etc.), light emitting transistor elements (transists that emit light according to current), electron emitting elements, liquid crystal elements, electrons. Ink element, electrophoretic element, electrowetting element, plasma display (PDP), MEMS (micro electromechanical system) display (for example, grating light valve (G)
LV), digital micromirror device (DMD), digital micro shutter (DMS) element, interference modulation (IMOD) element, etc.), piezoelectric ceramic display and the like.

Further, as an example of a display device using an EL element, there is an EL display or the like. As an example of a display device using an electron emitting element, a field emission display (FE)
D) or SED flat display (SED: Surface-conduccio)
n Electron-emitter Display) and the like. An example of a display device using a liquid crystal element is a liquid crystal display (transmissive liquid crystal display, semi-transmissive liquid crystal display, reflective liquid crystal display, direct-view liquid crystal display, projection type liquid crystal display). As an example of a display device using an electronic ink element or an electrophoresis element,
There are electronic papers and so on. In the case of realizing a semi-transmissive liquid crystal display or a reflective liquid crystal display, a part or all of the pixel electrodes may have a function as a reflective electrode. For example, a part or all of the pixel electrodes may have aluminum, silver, or the like. Further, in that case, it is also possible to provide a storage circuit such as SRAM under the reflective electrode. Thereby, the power consumption can be further reduced.

As the display method in the display device 700, a progressive method, an interlaced method, or the like can be used. Further, as a color element controlled by pixels when displaying in color, R is used.
It is not limited to the three colors of GB (R stands for red, G stands for green, and B stands for blue). For example, it may be composed of four pixels of R pixel, G pixel, B pixel, and W (white) pixel. Alternatively, as in the pentile arrangement, one color element may be configured by two colors of RGB, and two different colors may be selected and configured depending on the color element. Alternatively, one or more colors such as yellow, cyan, and magenta may be added to RGB. The size of the display area may be different for each dot of the color element. However, the disclosed invention is not limited to the display device for color display, and can be applied to the display device for monochrome display.

Further, in order to display the display device in full color by using white light emission (W) for the backlight (organic EL element, inorganic EL element, LED, fluorescent lamp, etc.), a colored layer (also referred to as a color filter) may be used. good. The colored layer is, for example, red (R), green (G), and blue (B).
), Yellow (Y) and the like can be used in appropriate combinations. By using the colored layer, the color reproducibility can be improved as compared with the case where the colored layer is not used. At this time, the white light in the region without the colored layer may be directly used for display by arranging the region having the colored layer and the region without the colored layer. By arranging a region that does not have a colored layer in a part, it is possible to reduce the decrease in brightness due to the colored layer during bright display, and the power consumption is reduced to 2.
In some cases, it can be reduced by about 30%. However, when full-color display is performed using a self-luminous element such as an organic EL element or an inorganic EL element, R, G, B, Y, and W may be emitted from an element having each emission color. By using the self-luminous element, the power consumption may be further reduced as compared with the case of using the colored layer.

In addition to the above-mentioned method of converting part of the light emitted from white light emitted into red, green, and blue by passing it through a color filter (color filter method), the colorization method also emits red, green, and blue light. A method used for each (three-color method) or a method of converting a part of the light emitted from the blue light to red or green (color conversion method, quantum dot method) may be applied.

In the present embodiment, a configuration in which a liquid crystal element and an EL element are used as display elements will be described with reference to FIGS. 19 and 20. Note that FIG. 19 is a cross-sectional view of the alternate long and short dash line QR shown in FIG. 18, and has a configuration in which a liquid crystal element is used as the display element. Further, FIG. 20 is a cross-sectional view of the alternate long and short dash line QR shown in FIG. 18, and has a configuration in which an EL element is used as a display element.

First, the common parts shown in FIGS. 19 and 20 will be described first, and then the different parts will be described below.

<3-1. Explanation of common parts of display devices>
The display device 700 shown in FIGS. 19 and 20 includes a routing wiring unit 711, a pixel unit 702, a source driver circuit unit 704, and an FPC terminal unit 708. Further, the routing wiring portion 711 has a signal line 710. Further, the pixel unit 702 has a transistor 750 and a capacitive element 790. Further, the source driver circuit unit 704 has a transistor 752.

The transistor 750 and the transistor 752 have the same configuration as the transistor 150 shown above. As for the configurations of the transistor 750 and the transistor 752, other transistors shown in the previous embodiment may be used.

The transistor used in this embodiment has an oxide semiconductor film that has been purified to a high degree and suppresses the formation of oxygen deficiency. The transistor can reduce the off-current. Therefore, the holding time of an electric signal such as an image signal can be lengthened, and the writing interval can be set long when the power is on. Therefore, the frequency of the refresh operation can be reduced, which has the effect of suppressing power consumption.

Further, since the transistor used in this embodiment can obtain a relatively high field effect mobility, it can be driven at high speed. For example, by using such a transistor capable of high-speed driving in a liquid crystal display device, a switching transistor in a pixel portion and a driver transistor used in a driving circuit portion can be formed on the same substrate. That is, since it is not necessary to separately use a semiconductor device formed of a silicon wafer or the like as a drive circuit, the number of parts of the semiconductor device can be reduced. Further, even in the pixel portion, by using a transistor capable of high-speed driving, it is possible to provide a high-quality image.

The capacitive element 790 has a first oxide semiconductor film of the transistor 750, a lower electrode formed through a step of processing the same oxide semiconductor film, and a conductivity that functions as a source electrode and a drain electrode of the transistor 750. It has a film and an upper electrode formed through a step of processing the same conductive film. Further, a step of forming the same insulating film as the insulating film that functions as the second insulating film of the transistor 750 and the insulating film that functions as the third insulating film is formed between the lower electrode and the upper electrode. An insulating film is provided through which the insulating film is formed. That is,
The capacitive element 790 has a laminated structure in which an insulating film functioning as a dielectric is sandwiched between a pair of electrodes.

Further, in FIGS. 19 and 20, a flattening insulating film 770 is provided on the transistor 750, the transistor 752, and the capacitive element 790.

As the flattening insulating film 770, a heat-resistant organic material such as a polyimide resin, an acrylic resin, a polyimideamide resin, a benzocyclobutene resin, a polyamide resin, or an epoxy resin can be used. The flattening insulating film 770 may be formed by laminating a plurality of insulating films formed of these materials. Further, the flattening insulating film 770 may not be provided.

Further, the signal line 710 is formed through the same steps as the conductive film that functions as the source electrode and the drain electrode of the transistors 750 and 752. The signal line 710 is a conductive film formed through a process different from that of the source and drain electrodes of the transistors 750 and 752, for example, an oxide semiconductor formed through the same process as an oxide semiconductor film functioning as a gate electrode. A membrane may be used. When a material containing a copper element is used as the signal line 710, for example, signal delay due to wiring resistance is small, and display on a large screen is possible.

Further, the FPC terminal portion 708 includes a connection electrode 760, an anisotropic conductive film 780, and an FPC 71.
Has 6. The connection electrode 760 is formed through the same steps as the conductive film that functions as the source electrode and the drain electrode of the transistors 750 and 752. Further, the connection electrode 760 is electrically connected to the terminal of the FPC 716 via the anisotropic conductive film 780.

Further, as the first substrate 701 and the second substrate 705, for example, a glass substrate can be used. Further, a flexible substrate may be used as the first substrate 701 and the second substrate 705. Examples of the flexible substrate include a plastic substrate and the like.

Further, a structure 778 is provided between the first substrate 701 and the second substrate 705. The structure 778 is a columnar spacer obtained by selectively etching the insulating film.
It is provided to control the distance (cell gap) between the first substrate 701 and the second substrate 705. A spherical spacer may be used as the structure 778.

Further, on the second substrate 705 side, a light-shielding film 738 that functions as a black matrix and
A colored film 736 that functions as a color filter, and an insulating film 734 that is in contact with the light-shielding film 738 and the colored film 736 are provided.

<3-2. Configuration example of a display device using a liquid crystal element>
The display device 700 shown in FIG. 19 has a liquid crystal element 775. The liquid crystal element 775 has a conductive film 772, a conductive film 774, and a liquid crystal layer 776. The conductive film 774 is a second substrate 705.
It is provided on the side and has a function as a counter electrode. The display device 700 shown in FIG. 19 can display an image by controlling the transmission and non-transmission of light by changing the orientation state of the liquid crystal layer 776 by the voltage applied to the conductive film 772 and the conductive film 774.

Further, the conductive film 772 is connected to a conductive film that functions as a source electrode and a drain electrode of the transistor 750. The conductive film 772 is formed on the flattening insulating film 770 and functions as a pixel electrode, that is, one electrode of the display element. Further, the conductive film 772 has a function as a reflective electrode. The display device 700 shown in FIG. 19 is a so-called reflective color liquid crystal display device that uses external light to reflect light by the conductive film 772 and display the light through the colored film 736.

As the conductive film 772, a conductive film having a translucent light in visible light or a conductive film having a reflective property in visible light can be used. As a conductive film having translucency in visible light,
For example, a material containing one selected from indium (In), zinc (Zn), and tin (Sn) may be used. As the conductive film having a reflective property in visible light, for example, a material containing aluminum or silver may be used. In the present embodiment, as the conductive film 772,
A reflective conductive film is used in visible light.

Further, in the display device 700 shown in FIG. 19, unevenness is provided in a part of the flattening insulating film 770 of the pixel portion 702. The unevenness can be formed, for example, by forming a flattening insulating film 770 with a resin film and providing unevenness on the surface of the resin film. Further, the conductive film 772 that functions as a reflective electrode is formed along the above-mentioned unevenness. Therefore, the external light is conductive film 772.
When the light is incident on the conductive film 772, the light can be diffusely reflected on the surface of the conductive film 772, and the visibility can be improved.

The display device 700 shown in FIG. 19 is an example of a reflective color liquid crystal display device, but the present invention is not limited to this. For example, the conductive film 772 is transmitted in visible light by using a translucent conductive film. It may be a type color liquid crystal display device. In the case of the transmissive color liquid crystal display device, the unevenness provided on the flattening insulating film 770 may not be provided.

Although not shown in FIG. 19, an alignment film may be provided on each side of the conductive films 772 and 774 in contact with the liquid crystal layer 776. Further, although not shown in FIG. 19, an optical member (optical substrate) such as a polarizing member, a retardation member, and an antireflection member may be appropriately provided. For example, circular polarization using a polarizing substrate and a retardation substrate may be used. Further, a backlight, a side light or the like may be used as the light source.

When a liquid crystal element is used as the display element, a thermotropic liquid crystal, a low molecular weight liquid crystal, a polymer liquid crystal, a polymer dispersion type liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, or the like can be used. These liquid crystal materials show a cholesteric phase, a smectic phase, a cubic phase, a chiral nematic phase, an isotropic phase and the like depending on the conditions.

Further, when the transverse electric field method is adopted, a liquid crystal showing a blue phase without using an alignment film may be used. The blue phase is one of the liquid crystal phases, and is a phase that appears immediately before the transition from the cholesteric phase to the isotropic phase when the temperature of the cholesteric liquid crystal is raised. Since the blue phase is expressed only in a narrow temperature range, a liquid crystal composition mixed with a chiral agent of several weight% or more is used for the liquid crystal layer in order to improve the temperature range. A liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent may be used.
Since the response speed is short and it is optically isotropic, no alignment treatment is required. In addition, since it is not necessary to provide an alignment film, the rubbing process is not required, so that electrostatic breakdown caused by the rubbing process can be prevented, and defects and breakage of the liquid crystal display device during the manufacturing process can be reduced. .. Further, the liquid crystal material showing the blue phase has a small viewing angle dependence.

When a liquid crystal element is used as the display element, TN (Twisted Nematic)
) Mode, IPS (In-Plane-Switching) mode, FFS (Frin)
get Field Switching) mode, ASM (Axially System)
tric aligned Micro-cell mode, OCB (Optical)
Combined Birefringence mode, FLC (Ferroe)
liquid Crystal Crystal) mode, AFLC (AntiFerr)
Authentic Liquid Crystal) mode and the like can be used.

Further, a normally black type liquid crystal display device, for example, a transmissive type liquid crystal display device adopting a vertical orientation (VA) mode may be used. There are several vertical orientation modes, for example, MVA (Multi-Domain Vertical Alignment).
) Mode, PVA (Patterned Vertical Alignment) mode, ASV mode and the like can be used.

<3-3. Display device using light emitting element>
The display device 700 shown in FIG. 20 has a light emitting element 782. The light emitting element 782 has a conductive film 784, an EL layer 786, and a conductive film 788. The display device 700 shown in FIG. 20 can display an image by emitting light from the EL layer 786 of the light emitting element 782.

Further, the conductive film 784 is connected to a conductive film that functions as a source electrode and a drain electrode of the transistor 750. The conductive film 784 is formed on the flattening insulating film 770 and functions as a pixel electrode, that is, one electrode of the display element. As the conductive film 784, a conductive film having a translucent light in visible light or a conductive film having a reflective property in visible light can be used. As the conductive film having translucency in visible light, for example, a material containing one selected from indium (In), zinc (Zn), and tin (Sn) may be used. As the conductive film having a reflective property in visible light, for example, a material containing aluminum or silver may be used.

Further, in the display device 700 shown in FIG. 20, an insulating film 730 is provided on the flattening insulating film 770 and the conductive film 784. The insulating film 730 covers a part of the conductive film 784. The light emitting element 782 has a top emission structure. Therefore, the conductive film 788 has translucency and is E.
It transmits the light emitted by the L layer 786. In the present embodiment, the top emission structure is exemplified, but the present invention is not limited to this. For example, it can be applied to a bottom emission structure that emits light to the conductive film 784 side and a dual emission structure that emits light to both the conductive film 784 and the conductive film 788.

Further, a colored film 736 is provided at a position overlapping with the light emitting element 782, and a light shielding film 738 is provided at a position overlapping with the insulating film 730, the routing wiring portion 711, and the source driver circuit portion 704. Further, the colored film 736 and the light-shielding film 738 are covered with the insulating film 734. Further, the space between the light emitting element 782 and the insulating film 734 is filled with the sealing film 732. In addition, FIG. 20
In the display device 700 shown in the above, the configuration in which the colored film 736 is provided has been exemplified, but the present invention is not limited thereto. For example, when the EL layer 786 is formed by painting separately, the colored film 736 may not be provided.

The configuration shown in this embodiment can be used in combination with the configurations shown in other embodiments as appropriate.

(Embodiment 4)
In the present embodiment, an example of a circuit configuration of a semiconductor device, which can retain the stored contents even when power is not supplied and has no limit on the number of writes, will be described with reference to FIG. 21.

<4-1. Circuit configuration>
FIG. 21 is a diagram illustrating a circuit configuration of a semiconductor device. In FIG. 21, the first wiring (
The 1st Line) and one of the source electrode or the drain electrode of the p-type transistor 1280a are electrically connected. Further, the other of the source electrode or the drain electrode of the p-type transistor 1280a and one of the source electrode or the drain electrode of the n-type transistor 1280b are electrically connected. Further, the other of the source electrode or the drain electrode of the n-type transistor 1280b and one of the source electrode or the drain electrode of the n-type transistor 1280c are electrically connected.

Further, the second wiring (2nd Line) and one of the source electrode and the drain electrode of the transistor 1282 are electrically connected. Further, the other of the source electrode or the drain electrode of the transistor 1282, one of the electrodes of the capacitive element 1281 and the gate electrode of the n-type transistor 1280c are electrically connected.

Further, the third wiring (3rd Line) and the gate electrodes of the p-type transistor 1280a and the n-type transistor 1280b are electrically connected. Also, the fourth wiring (4)
th Line) and the gate electrode of the transistor 1282 are electrically connected. Further, the fifth wiring (5th Line) is electrically connected to the other of the electrodes of the capacitive element 1281 and the other of the source electrode or the drain electrode of the n-type transistor 1280c. Further, the sixth wiring (6th Line) and the other of the source electrode or drain electrode of the p-type transistor 1280a and one of the source electrode or drain electrode of the n-type transistor 1280b are electrically connected.

The transistor 1282 is an oxide semiconductor (OS: Oxide Semiconductor).
It can be formed by uctor). Therefore, in FIG. 21, the symbol “OS” is added to the transistor 1282. The transistor 1282 may be formed of a material other than the oxide semiconductor.

Further, in FIG. 21, a floating node (FN) is added at the connection point between the other of the source electrode or the drain electrode of the transistor 1282, one of the electrodes of the capacitive element 1281, and the gate electrode of the n-type transistor 1280c. There is. By turning off the transistor 1282, the floating node, one of the electrodes of the capacitive element 1281, and n
The potential given to the gate electrode of the type transistor 1280c can be held.

In the circuit configuration shown in FIG. 21, information can be written, held, and read as follows by taking advantage of the feature that the potential of the gate electrode of the n-type transistor 1280c can be held.

<4-2. Writing and retaining information>
First, writing and holding of information will be described. The potential of the fourth wiring is set to the potential at which the transistor 1282 is turned on, and the transistor 1282 is turned on. As a result, the potential of the second wiring is the gate electrode of the n-type transistor 1280c and the capacitive element 12.
Given to 81. That is, a predetermined charge is given to the gate electrode of the n-type transistor 1280c (writing). After that, the potential of the fourth wiring is set to the potential at which the transistor 1282 is turned off, and the transistor 1282 is turned off. As a result, the electric charge given to the gate electrode of the n-type transistor 1280c is retained (retained).

Since the off-current of the transistor 1282 is extremely small, the charge of the gate electrode of the n-type transistor 1280c is retained for a long time.

<4-3. Reading information>
Next, reading information will be described. When the potential of the third wiring is set to the Low level potential, the p-type transistor 1280a is turned on and the n-type transistor 1280b is turned off. At this time, the potential of the first wiring is given to the sixth wiring. On the other hand, when the potential of the third wiring is set to the high level potential, the p-type transistor 1280a is turned off, and n
The type transistor 1280b is turned on. At this time, the sixth wiring takes different potentials depending on the amount of electric charge held in the floating node (FN). Therefore, the retained information can be read out by looking at the potential of the sixth wiring (reading).

Further, since the transistor 1282 uses an oxide semiconductor for the channel forming region, the transistor 1282 is a transistor having an extremely small off-current. Since the off-current of the transistor 1282 using the oxide semiconductor is less than 1 / 100,000 of the off-current of the transistor formed of silicon semiconductor or the like, the electric charge accumulated in the floating node (FN) due to the leakage of the transistor 1282. It is possible to ignore the disappearance of. That is, the transistor 1282 using the oxide semiconductor makes it possible to realize a non-volatile storage circuit capable of holding information without supplying electric power.

Further, by using a semiconductor device using such a circuit configuration for a storage device such as a register or a cache memory, it is possible to prevent data loss in the storage device due to a stop supply of the power supply voltage. Further, after restarting the supply of the power supply voltage, it is possible to return to the state before the power supply is stopped in a short time. Therefore, in the entire storage device or one or a plurality of logic circuits constituting the storage device, the power can be stopped even for a short time in the standby state, so that the power consumption can be suppressed.

As described above, the configurations and methods shown in the present embodiment can be appropriately combined with the configurations and methods shown in other embodiments.

(Embodiment 5)
In the present embodiment, the configuration of the pixel circuit that can be used in the semiconductor device of one aspect of the present invention will be described below with reference to FIG. 22 (A).

<5-1. Pixel circuit configuration>
FIG. 22A is a diagram illustrating a configuration of a pixel circuit. The circuit shown in FIG. 22 (A) includes a photoelectric conversion element 1360, a transistor 1351, a transistor 1352, and a transistor 13.
It has 53 and a transistor 1354.

The anode of the photoelectric conversion element 1360 is connected to the wiring 1316, and the cathode is connected to either the source electrode or the drain electrode of the transistor 1351. The other of the source or drain electrodes of the transistor 1351 is connected to the charge storage unit (FD) and the gate electrode is connected to the wiring 1312 (TX). One of the source or drain electrodes of the transistor 1352 is connected to the wiring 1314 (GND), the other of the source or drain electrodes is connected to one of the source or drain electrodes of the transistor 1354, and the gate electrode is a charge storage unit (FD). ) Is connected. One of the source or drain electrodes of the transistor 1353 is connected to the charge storage unit (FD), the other of the source or drain electrodes is connected to the wiring 1317, and the gate electrode is connected to the wiring 1311 (RS). Transistor 1
The other of the source or drain electrodes of 354 is connected to wiring 1315 (OUT) and the gate electrode is connected to wiring 1313 (SE). All of the above connections are electrical connections.

The wiring 1314 may be supplied with a potential such as GND, VSS, and VDD. Here, the potential and voltage are relative. Therefore, the magnitude of the potential of GND is not always 0 volts.

The photoelectric conversion element 1360 is a light receiving element and has a function of generating a current according to the light incident on the pixel circuit. The transistor 1353 is a charge storage unit (F) by the photoelectric conversion element 1360.
It has a function of controlling charge accumulation in D). The transistor 1354 is a charge storage unit (FD).
) Has a function to output a signal according to the potential. The transistor 1352 is a charge storage unit (
It has a function of resetting the potential of FD). The transistor 1352 has a function of controlling the selection of the pixel circuit at the time of reading.

The charge storage unit (FD) is a charge holding node and holds a charge that changes according to the amount of light received by the photoelectric conversion element 1360.

The transistor 1352 and the transistor 1354 are the wiring 1315 and the wiring 131.
It suffices if it is connected in series with 4. Therefore, the wiring 1314 and the transistor 13
52, the transistor 1354, and the wiring 1315 may be arranged in this order, or the wiring 1314, the transistor 1354, the transistor 1352, and the wiring 1315 may be arranged in this order.

The wiring 1311 (RS) has a function as a signal line for controlling the transistor 1353. The wiring 1312 (TX) has a function as a signal line for controlling the transistor 1351. The wiring 1313 (SE) has a function as a signal line for controlling the transistor 1354. The wiring 1314 (GND) has a function as a signal line for setting a reference potential (for example, GND). The wiring 1315 (OUT) is a transistor 1352.
It has a function as a signal line for reading a signal output from. The wiring 1316 has a function as a signal line for outputting a charge from the charge storage unit (FD) via the photoelectric conversion element 1360, and is a low potential line in the circuit of FIG. 22 (A). Further, the wiring 1317 has a function as a signal line for resetting the potential of the charge storage unit (FD), and is a high potential line in the circuit of FIG. 22 (A).

Next, the configuration of each element shown in FIG. 22 (A) will be described.

<5-2. Photoelectric conversion element>
As the photoelectric conversion element 1360, an element having selenium or a compound containing selenium (hereinafter referred to as a selenium-based material) or an element having silicon (for example, an element having a pin-type junction formed) can be used. Further, it is preferable to combine a transistor using an oxide semiconductor and a photoelectric conversion element using a selenium-based material because the reliability can be improved.

<5-3. Transistor>
The transistor 1351, transistor 1352, transistor 1353, and transistor 1354 can be formed by using silicon semiconductors such as amorphous silicon, microcrystalline silicon, polycrystalline silicon, and monocrystalline silicon, but oxide semiconductors can be formed. It is preferably formed by the transistor used. A transistor in which a channel forming region is formed of an oxide semiconductor has a characteristic of exhibiting extremely low off-current characteristics. Further, as the transistor in which the channel forming region is formed of the oxide semiconductor, for example, the transistor shown in the first embodiment can be used.

In particular, if the leakage current of the transistor 1351 and the transistor 1353 connected to the charge storage unit (FD) is large, the time that the charge stored in the charge storage unit (FD) can be held becomes insufficient. Therefore, by using a transistor using an oxide semiconductor for at least the two transistors, it is possible to prevent unnecessary charge from flowing out from the charge storage unit (FD).

Further, also in the transistor 1352 and the transistor 1354, if the leakage current is large, an unnecessary charge output occurs in the wiring 1314 or the wiring 1315. Therefore, as these transistors, a transistor in which a channel formation region is formed of an oxide semiconductor is used. It is preferable to use it.

Further, in FIG. 22A, a transistor having one gate electrode configuration is illustrated, but the present invention is not limited to this, and for example, a configuration having a plurality of gate electrodes may be used. Examples of the transistor having a plurality of gate electrodes include a first gate electrode and a second gate electrode (also referred to as a back gate electrode) in which a semiconductor film in which a channel forming region is formed overlaps.
It may be configured to have. As the back gate electrode, for example, the same potential as the first gate electrode, floating, or a potential different from that of the first gate electrode may be applied.

<5-4. Circuit operation timing chart>
Next, an example of the circuit operation of the circuit shown in FIG. 22 (A) will be described using the timing chart shown in FIG. 22 (B).

For the sake of brief description in FIG. 22B, the potential of each wiring is given as a signal that changes in binary. However, since each potential is an analog signal, it is actually possible to take various values, not limited to binary values, depending on the situation. The signal 1401 shown in FIG. 22B is the potential of the wiring 1311 (RS), the signal 1402 is the potential of the wiring 1312 (TX), the signal 1403 is the potential of the wiring 1313 (SE), and the signal 1404 is the charge storage unit (FD). ) Potential, signal 1405 is wiring 1315 (OUT)
) Corresponds to the potential. The potential of the wiring 1316 is always "Low", and the potential of the wiring 1317 is always "High".

At time A, the potential (signal 1401) of the wiring 1311 is set to "High", and the wiring 1312.
When the potential (signal 1402) of is set to "High", the potential of the charge storage unit (FD) (signal 14)
04) is initialized to the potential (“High”) of the wiring 1317, and the reset operation is started. The potential (signal 1405) of the wiring 1315 is precharged to "High".

At time B, when the potential (signal 1401) of the wiring 1311 is set to "Low", the reset operation ends and the accumulation operation starts. Here, since the photoelectric conversion element 1360 is subjected to the reverse bias, the charge distribution unit (FD) (signal 1404) begins to decrease due to the reverse current. Since the reverse current of the photoelectric conversion element 1360 increases when the light is irradiated, the rate of decrease of the potential (signal 1404) of the charge storage unit (FD) changes according to the amount of the irradiated light. That is, the channel resistance between the source and drain of the transistor 1354 changes according to the amount of light irradiating the photoelectric conversion element 1360.

At time C, when the potential (signal 1402) of the wiring 1312 is set to “Low”, the storage operation ends, and the potential (signal 1404) of the charge storage unit (FD) becomes constant. Here, the potential is determined by the amount of electric charge generated by the photoelectric conversion element 1360 during the storage operation. That is, it changes according to the amount of light radiated to the photoelectric conversion element 1360. Also, the transistor 135
Since 1 and the transistor 1353 are composed of a transistor having a channel forming region formed of an oxide semiconductor and having an extremely low off-current, the potential of the charge storage unit (FD) is kept until the subsequent selection operation (reading operation) is performed. It is possible to keep it constant.

When the potential of the wiring 1312 (signal 1402) is set to "Low", the potential of the charge storage unit (FD) may change due to the parasitic capacitance between the wiring 1312 and the charge storage unit (FD). be. If the amount of change in the potential is large, the photoelectric conversion element 136 during the storage operation.
It means that the amount of electric charge generated by 0 cannot be accurately obtained. In order to reduce the amount of change in the potential, the charge storage unit (FD) that reduces the capacitance between the gate electrode and the source electrode (or the gate electrode and the drain electrode) of the transistor 1351 and increases the gate capacitance of the transistor 1352.
) Is effective, such as providing a holding capacity. In this embodiment, the change in the potential can be ignored by these measures.

When the potential (signal 1403) of the wiring 1313 is set to "High" at time D, the transistor 1354 conducts and the selection operation is started, and the wiring 1314 and the wiring 1315 conduct with each other via the transistor 1352 and the transistor 1354. Then, the potential of the wiring 1315 (
The signal 1405) decreases. The precharge of the wiring 1315 may be completed before the time D. Here, the speed at which the potential (signal 1405) of the wiring 1315 drops is
It depends on the current between the source electrode and the drain electrode of the transistor 1352. That is, it changes according to the amount of light radiated to the photoelectric conversion element 1360 during the storage operation.

When the potential of the wiring 1313 (signal 1403) is set to "Low" at time E, the transistor 1354 is cut off, the selection operation ends, and the potential of the wiring 1315 (signal 1405) becomes a constant value. Here, the value that becomes a constant value changes according to the amount of light that has been applied to the photoelectric conversion element 1360. Therefore, by acquiring the potential of the wiring 1315, it is possible to know the amount of light irradiated to the photoelectric conversion element 1360 during the storage operation.

More specifically, when the light shining on the photoelectric conversion element 1360 is strong, the charge storage unit (F)
The potential of D), that is, the gate voltage of the transistor 1352 decreases. Therefore, the current flowing between the source electrode and the drain electrode of the transistor 1352 becomes small, and the wiring 1315
The potential of (signal 1405) drops slowly. Therefore, a relatively high potential can be read out from the wiring 1315.

On the contrary, when the light shining on the photoelectric conversion element 1360 is weak, the potential of the charge storage unit (FD), that is, the gate voltage of the transistor 1352 becomes high. Therefore, the transistor 1
The current flowing between the source electrode and the drain electrode of 352 becomes large, and the potential of the wiring 1315 (
The signal 1405) drops fast. Therefore, a relatively low potential can be read out from the wiring 1315.

This embodiment can be implemented in combination with the configurations described in other embodiments as appropriate.

(Embodiment 6)
In the present embodiment, a display device having the semiconductor device of one aspect of the present invention will be described with reference to FIG. 23.

<6. Display device circuit configuration>
The display device shown in FIG. 23A has a region having pixels of the display element (hereinafter referred to as a pixel unit 502) and a circuit unit (hereinafter referred to as a pixel unit 502) having a circuit arranged outside the pixel unit 502 and for driving the pixels.
Hereinafter, a circuit having a drive circuit unit 504 and a device protection function (hereinafter, protection circuit 50).
6) and a terminal portion 507. The protection circuit 506 may not be provided.

It is desirable that a part or all of the drive circuit unit 504 is formed on the same substrate as the pixel unit 502. This makes it possible to reduce the number of parts and the number of terminals. Drive circuit unit 504
When a part or all of is not formed on the same substrate as the pixel part 502, a part or all of the drive circuit part 504 is COG or TAB (Tape Automated B).
It can be implemented by onding).

The pixel unit 502 has a circuit (hereinafter referred to as a pixel circuit 501) for driving a plurality of display elements arranged in the X row (X is a natural number of 2 or more) and the Y column (Y is a natural number of 2 or more). The drive circuit unit 504 is a circuit for outputting a signal (scanning signal) for selecting a pixel (hereinafter referred to as a gate driver 504a) and a circuit for supplying a signal (data signal) for driving a display element of the pixel (hereinafter referred to as a gate driver 504a). Hereinafter, it has a drive circuit such as a source driver 504b).

The gate driver 504a has a shift register and the like. The gate driver 504a is
A signal for driving the shift register is input via the terminal unit 507, and the signal is output. For example, the gate driver 504a receives a start pulse signal, a clock signal, and the like, and outputs a pulse signal. The gate driver 504a has a function of controlling the potential of the wiring (hereinafter referred to as scanning lines GL_1 to GL_X) to which the scanning signal is given. A plurality of gate drivers 504a may be provided, and the scanning lines GL_1 to GL_X may be divided and controlled by the plurality of gate drivers 504a. Alternatively, the gate driver 504a has a function of being able to supply an initialization signal. However, the present invention is not limited to this, and the gate driver 50
4a can also supply another signal.

The source driver 504b has a shift register and the like. The source driver 504b
In addition to the signal for driving the shift register, a signal (image signal) that is the source of the data signal is input via the terminal unit 507. The source driver 504b has a function of generating a data signal to be written in the pixel circuit 501 based on the image signal. Further, the source driver 504b has a function of controlling the output of a data signal according to a pulse signal obtained by inputting a start pulse, a clock signal, or the like. Further, the source driver 504b has a function of controlling the potential of the wiring (hereinafter referred to as data lines DL_1 to DL_Y) to which the data signal is given. Alternatively, the source driver 504b has a function of being able to supply an initialization signal. However, the present invention is not limited to this, and the source driver 504b can also supply another signal.

The source driver 504b is configured by using, for example, a plurality of analog switches.
The source driver 504b sequentially turns on a plurality of analog switches by turning them on.
A time-division signal of an image signal can be output as a data signal. Further, the source driver 504b may be configured by using a shift register or the like.

In each of the plurality of pixel circuits 501, a pulse signal is input via one of the plurality of scanning lines GL to which the scanning signal is given, and the data signal is transmitted through one of the plurality of data line DLs to which the data signal is given. Entered. Also. In each of the plurality of pixel circuits 501, the writing and holding of data of the data signal is controlled by the gate driver 504a. For example, in the pixel circuit 501 in the mth row and nth column, a pulse signal is input from the gate driver 504a via the scanning line GL_m (m is a natural number of X or less), and the data line DL_n (m is a natural number of X or less) is input according to the potential of the scanning line GL_m.
A data signal is input from the source driver 504b via (n is a natural number equal to or less than Y).

The protection circuit 506 shown in FIG. 23A is, for example, a gate driver 504a and a pixel circuit 5.
It is connected to the scanning line GL, which is the wiring between 01. Alternatively, the protection circuit 506 is connected to the data line DL, which is the wiring between the source driver 504b and the pixel circuit 501. Alternatively, the protection circuit 506 can be connected to the wiring between the gate driver 504a and the terminal portion 507. Alternatively, the protection circuit 506 can be connected to the wiring between the source driver 504b and the terminal portion 507. The terminal portion 507 refers to a portion provided with a terminal for inputting a power supply, a control signal, and an image signal from an external circuit to the display device.

The protection circuit 506 is a circuit that makes the wiring and another wiring in a conductive state when a potential outside a certain range is applied to the wiring to which the protection circuit 506 is connected.

As shown in FIG. 23 (A), the protection circuit 50 is attached to the pixel unit 502 and the drive circuit unit 504, respectively.
By providing 6, ESD (Electrostatic Discharge:
It is possible to increase the resistance of the display device to the overcurrent generated by (electrostatic discharge) or the like.
However, the configuration of the protection circuit 506 is not limited to this, and for example, the configuration may be such that the protection circuit 506 is connected to the gate driver 504a or the protection circuit 506 is connected to the source driver 504b. Alternatively, the protection circuit 506 may be connected to the terminal portion 507.

Further, FIG. 23A shows an example in which the drive circuit unit 504 is formed by the gate driver 504a and the source driver 504b, but the configuration is not limited to this. For example, a configuration may be configured in which only the gate driver 504a is formed and a substrate on which a separately prepared source driver circuit is formed (for example, a drive circuit board formed of a single crystal semiconductor film or a polycrystalline semiconductor film) is mounted.

Further, the plurality of pixel circuits 501 shown in FIG. 23 (A) can have the configuration shown in FIG. 23 (B), for example.

The pixel circuit 501 shown in FIG. 23B has a liquid crystal element 570, a transistor 550, and a capacitive element 560. The transistor shown in the previous embodiment can be applied to the transistor 550.

The potential of one of the pair of electrodes of the liquid crystal element 570 is appropriately set according to the specifications of the pixel circuit 501. The orientation state of the liquid crystal element 570 is set according to the written data. A common potential (common potential) may be applied to one of the pair of electrodes of the liquid crystal element 570 of each of the plurality of pixel circuits 501. Further, different potentials may be applied to one of the pair of electrodes of the liquid crystal element 570 of the pixel circuit 501 of each row.

For example, as a method of driving a display device including a liquid crystal element 570, a TN mode, an STN mode, a VA mode, and an ASM (Axially Symmetrically Defined M) are used.
icro-cell) mode, OCB (Optically Complied)
Birefringence mode, FLC (Ferroelectric Liqu)
id Crystal) mode, AFLC (AntiFerolectric Li)
Kid Crystal) mode, MVA mode, PVA (Patterned Ve)
vertical Alignment) mode, IPS mode, FFS mode, or TBA
(Transverse Bend Alignment) mode and the like may be used.
In addition to the above-mentioned driving method, the display device can be driven by ECB (Electric).
allly Controlled Birefringence) mode, PDLC (P)
olymer Dispersed Liquid Crystal) mode, PNLC
(Polymer Network Liquid Crystal) mode, guest host mode, and the like. However, the present invention is not limited to this, and various liquid crystal elements and various driving methods thereof can be used.

In the pixel circuit 501 in the m-th row and n-th column, one of the source electrode or the drain electrode of the transistor 550 is electrically connected to the data line DL_n, and the other is electrically connected to the other of the pair of electrodes of the liquid crystal element 570. To. Further, the gate electrode of the transistor 550 is a scanning line G.
It is electrically connected to L_m. The transistor 550 has a function of controlling data writing of a data signal by being turned on or off.

One of the pair of electrodes of the capacitive element 560 is a wiring to which a potential is supplied (hereinafter, potential supply line VL).
), And the other is electrically connected to the other of the pair of electrodes of the liquid crystal element 570. The potential value of the potential supply line VL is appropriately set according to the specifications of the pixel circuit 501. The capacitive element 560 has a function as a holding capacitance for holding the written data.

For example, in the display device having the pixel circuit 501 of FIG. 23 (B), for example, FIG. 23 (A).
The pixel circuit 501 of each row is sequentially selected by the gate driver 504a shown in the above, the transistor 550 is turned on, and the data of the data signal is written.

The pixel circuit 501 in which the data is written is put into a holding state when the transistor 550 is turned off. By doing this sequentially line by line, the image can be displayed.

Further, the plurality of pixel circuits 501 shown in FIG. 23 (A) can be configured as shown in FIG. 23 (C), for example.

Further, the pixel circuit 501 shown in FIG. 23 (C) has transistors 552, 554, a capacitive element 562, and a light emitting element 572. Transistor 552 and transistor 554
The transistor shown in the previous embodiment can be applied to either or both of the above.

One of the source electrode and the drain electrode of the transistor 552 is electrically connected to a wiring (hereinafter referred to as a signal line DL_n) to which a data signal is given. Further, the transistor 55
The gate electrode 2 is electrically connected to a wiring (hereinafter referred to as a scanning line GL_m) to which a gate signal is given.

The transistor 552 has a function of controlling data writing of a data signal by being turned on or off.

One of the pair of electrodes of the capacitive element 562 is a wiring to which a potential is applied (hereinafter, potential supply line VL).
It is electrically connected to (referred to as _a), and the other is electrically connected to the other of the source electrode and the drain electrode of the transistor 552.

The capacitance element 562 has a function as a holding capacitance for holding the written data.

One of the source electrode and the drain electrode of the transistor 554 is electrically connected to the potential supply line VL_a. Further, the gate electrode of the transistor 554 is electrically connected to the other of the source electrode and the drain electrode of the transistor 552.

One of the anode and cathode of the light emitting device 572 is electrically connected to the potential supply line VL_b, and the other is electrically connected to the other of the source electrode and the drain electrode of the transistor 554.

As the light emitting element 572, for example, an organic electroluminescence element (also referred to as an organic EL element) or the like can be used. However, the light emitting element 572 is not limited to this, and an inorganic EL element made of an inorganic material may be used.

One of the potential supply line VL_a and the potential supply line VL_b is given a high power supply potential VDD, and the other is given a low power supply potential VSS.

In the display device having the pixel circuit 501 of FIG. 23 (C), for example, the pixel circuit 501 of each row is sequentially selected by the gate driver 504a shown in FIG. 23 (A), the transistor 552 is turned on, and the data of the data signal is input. Write.

The pixel circuit 501 in which the data is written is put into a holding state when the transistor 552 is turned off. Further, the amount of current flowing between the source electrode and the drain electrode of the transistor 554 is controlled according to the potential of the written data signal, and the light emitting element 572 emits light with brightness corresponding to the amount of flowing current. By doing this sequentially line by line, the image can be displayed.

The configuration shown in this embodiment can be used in combination with the configurations shown in other embodiments as appropriate.

(Embodiment 7)
In this embodiment, an example of the applicable circuit configuration of the transistor described in the above-described embodiment will be described with reference to FIGS. 24 to 53.

In this embodiment, the transistor having the oxide semiconductor described in the previous embodiment is referred to as an OS transistor and will be described below.

<7. Inverter circuit configuration example>
FIG. 24A shows a circuit diagram of an inverter that can be applied to a shift register, a buffer, or the like included in the drive circuit. The inverter 800 outputs a signal obtained by inverting the logic of the input terminal IN to the output terminal OUT. The inverter 800 has a plurality of OS transistors. The signal SBG is a signal for varying the electrical characteristics of the OS transistor.

FIG. 24B is a circuit diagram as an example of the inverter 800. The inverter 800 is
It has an OS transistor 810 and an OS transistor 820. The inverter 800 can be manufactured as an n-channel type, and can have a so-called unipolar circuit configuration. Therefore, it can be manufactured at a lower cost than a CMOS inverter.

The OS transistors 810 and 820 have a first gate that functions as a front gate, a second gate that functions as a back gate, a first terminal that functions as one of the source or drain, and a second terminal that functions as the other of the source or drain. Has.

The first gate of the OS transistor 810 is connected to the second terminal. OS transistor 8
The second gate of 10 is connected to the wiring that transmits the signal SBG. The first terminal of the OS transistor 810 is connected to a wiring that gives a voltage VDD. The second terminal of the OS transistor 810 is connected to the output terminal OUT.

The first gate of the OS transistor 820 is connected to the input terminal IN. The second gate of the OS transistor 820 is connected to the input terminal IN. The first terminal of the OS transistor 820 is connected to the output terminal OUT. The second terminal of the OS transistor 820 is a voltage VSS.
Is connected to the wiring that gives.

FIG. 24C is a timing chart for explaining the operation of the inverter 800. The timing chart of FIG. 24C shows changes in the signal waveform of the input terminal IN, the signal waveform of the output terminal OUT, the signal waveform of the signal SBG, and the threshold voltage of the OS transistor 810 (FET810).

By giving the signal SBG to the second gate of the OS transistor 810, the threshold voltage (VTH) of the OS transistor 810 can be controlled.

The signal SBG has a voltage VBG_A for negatively shifting VTH and a voltage VBG_B for positively shifting VTH. By applying the voltage VBG_A to the second gate, the OS transistor 810 can be negatively shifted to the threshold voltage VTH_A. Further, by applying the voltage VBG_B to the second gate, the OS transistor 810 can be changed to the OS transistor 810.
It can be positively shifted to the threshold voltage VTH_B.

That is, the OS transistor 810 can be shifted to the curve represented by the broken line 840 by increasing the voltage of the second gate as shown in the graph shown in FIG. 25 (A). Further, by reducing the voltage of the second gate, it is possible to shift to the curve represented by the solid line 841.

By positively shifting to the threshold voltage VTH_B, the OS transistor 810 can be in a state in which current does not easily flow. As shown in FIG. 25 (B), the current IB flowing at this time can be made extremely small. Therefore, when the signal given to the input terminal IN is at a high level and the OS transistor 820 is in the ON state (ON), the voltage of the output terminal OUT can be sharply increased. Therefore, the signal waveform 831 of the output terminal in the timing chart shown in FIG. 24C can be changed sharply. Further, since the through current flowing between the wiring that gives the voltage VDD and the wiring that gives the voltage VSS can be reduced, the operation with low power consumption can be performed.

Further, by negatively shifting to the threshold voltage VTH_A, the OS transistor 81
0 can be set to a state in which current easily flows. As shown in FIG. 25 (C), the current IA flowing at this time can be at least larger than the current IB. Therefore, when the signal given to the input terminal IN is low level and the OS transistor 820 is in the OFF state (OFF), the voltage of the output terminal OUT can be sharply lowered. Therefore, FIG. 24 (C)
The signal waveform 832 of the output terminal in the timing chart shown in 1 can be changed sharply.

The VTH control of the OS transistor 810 by the signal SBG is performed by the OS transistor 8.
It is preferable to perform the operation before the state of 20 is switched, that is, before the time T1 or T2.
For example, as shown in FIG. 24C, the threshold voltage VTH_A is changed to the threshold voltage VTH_B before the time T1 when the signal given to the input terminal IN is switched to the high level.
It is preferable to switch the threshold voltage of the S transistor 810. In addition, FIG. 24 (C)
As shown in the above, it is preferable to switch the threshold voltage of the OS transistor 810 from the threshold voltage VTH_B to the threshold voltage VTH_A before the time T2 when the signal given to the input terminal IN switches to the low level.

Although the timing chart of FIG. 24C shows a configuration in which the signal SBG is switched according to the signal given to the input terminal IN, another configuration may be used. For example, the voltage for controlling the threshold voltage may be held in the second gate of the OS transistor 810 in a floating state. FIG. 26 shows an example of a circuit configuration that can realize the configuration.
Shown in (A).

In FIG. 26 (A), in addition to the circuit configuration shown in FIG. 24 (B), the OS transistor 850
Have. The first terminal of the OS transistor 850 is connected to the second gate of the OS transistor 810. Further, the second terminal of the OS transistor 850 is connected to a wiring that gives a voltage VBG_B (or a voltage VBG_A). The first gate of the OS transistor 850 is connected to the wiring that gives the signal SF. The second gate of the OS transistor 850 is a voltage VBG.
It is connected to a wiring that gives _B (or voltage VBG_A).

The operation of FIG. 26 (A) will be described with reference to the timing chart of FIG. 26 (B).

Similar to FIG. 24C, the voltage for controlling the threshold voltage of the OS transistor 810 is the second gate of the OS transistor 810 before the time T3 when the signal given to the input terminal IN switches to the high level. It is configured to be given to. The voltage VB for controlling the threshold voltage to the node NBG by setting the signal SF to the high level and turning on the OS transistor 850.
Give G_B.

After the node NBG becomes the voltage VBG_B, the OS transistor 850 is turned off. Since the off current of the OS transistor 850 is extremely small, the threshold voltage VTH_A once held by the node can be held by keeping the OS transistor 850 in the off state. Therefore, since the number of operations of applying the voltage VBG_B to the second gate of the OS transistor 850 is reduced, the power consumption required for rewriting the voltage VBG_B can be reduced.

In the circuit configurations of FIGS. 24 (B) and 26 (A), the configuration in which the voltage applied to the second gate of the OS transistor 810 is applied by external control is shown, but another configuration may be used. For example, a voltage for controlling the threshold voltage may be generated based on a signal given to the input terminal IN and given to the second gate of the OS transistor 810. An example of a circuit configuration in which the configuration can be realized is shown in FIG. 27 (A).

In FIG. 27A, in the circuit configuration shown in FIG. 24B, a CMOS inverter 860 is provided between the input terminal IN and the second gate of the OS transistor 810. The input terminal of the CMOS inverter 860 is connected to the input terminal IN. The output terminal of the CMOS inverter 860 is connected to the second gate of the OS transistor 810.

The operation of FIG. 27 (A) will be described with reference to the timing chart of FIG. 27 (B).
In the timing chart of FIG. 27B, the signal waveform of the input terminal IN, the signal waveform of the output terminal OUT, the output waveform IN_B of the CMOS inverter 860, and the OS transistor 810 are shown.
The change of the threshold voltage of (FET810) is shown.

The output waveform IN_B, which is a signal obtained by inverting the logic of the signal given to the input terminal IN, is shown in FIG. 24 (
Similar to C), the threshold voltage of the OS transistor 810 can be controlled. Therefore, although the voltage is different, the OS transistor 8 is as described with reference to FIGS. 25 (A) to 25 (C).
The threshold voltage of 10 can be controlled. For example, when the time T4 in FIG. 27 (B) is reached,
When the signal given to the input terminal IN is at a high level, the OS transistor 820 is turned on. At this time, the output waveform IN_B becomes low level. Therefore, the OS transistor 810 can be in a state in which current does not easily flow, and the voltage of the output terminal OUT can be steeply increased.

Further, when the time T5 in FIG. 27B is reached, the signal given to the input terminal IN is at a low level and the OS transistor 820 is turned off. At this time, the output waveform IN_B becomes a high level. Therefore, the OS transistor 810 can be in a state in which a current easily flows, and the voltage of the output terminal OUT can be steeply increased.

As described above, in the configuration of the present embodiment, the voltage of the back gate in the inverter having the OS transistor is switched according to the logic of the signal of the input terminal IN. With this configuration, the threshold voltage of the OS transistor can be controlled. By controlling the threshold voltage of the OS transistor together with the signal given to the input terminal IN, the change in the voltage of the output terminal OUT can be made steep. In addition, the penetration current between the wirings that give the power supply voltage can be reduced. Therefore, it is possible to reduce the power consumption.

The configuration shown in this embodiment can be used in combination with the configurations shown in other embodiments as appropriate.

(Embodiment 8)
In the present embodiment, the input / output device of one aspect of the present invention will be described with reference to FIG. 28.

<8. Input / output device configuration example>
The input / output device of one aspect of the present invention is an in-cell type touch panel having a function of displaying an image and a function of a touch sensor.

The display element included in the input / output device of one aspect of the present invention is not limited. Liquid crystal element, MEMS (M
Optical elements, organic EL (Electroluminescence) elements and light emitting diodes (LE) using icro Electro Mechanical System)
Various elements such as a light emitting element such as D: Light Emitting Diode) and an electrophoresis element can be applied as a display element.

In this embodiment, a transmissive liquid crystal display device using a transverse electric field type liquid crystal element will be described as an example.

The detection element (also referred to as a sensor element) included in the input / output device of one aspect of the present invention is not limited.
Various sensors that can detect the proximity or contact of the object to be detected such as a finger or stylus,
It can be applied as a detection element.

For example, as a sensor method, various methods such as a capacitance method, a resistance film method, a surface acoustic wave method, an infrared method, an optical method, and a pressure sensitive method can be used.

In this embodiment, an input / output device having a capacitance type detection element will be described as an example.

As the capacitance method, there are a surface type capacitance method, a projection type capacitance method and the like. Further, as the projection type capacitance method, there are a self-capacitance method, a mutual capacitance method and the like. It is preferable to use the mutual capacitance method because simultaneous multipoint detection is possible.

Typical in-cell type touch panels include a semi-in-cell type and a full-in-cell type. The semi-incell type refers to a configuration in which electrodes or the like constituting the detection element are provided on both the substrate supporting the display element and the facing substrate or only on the facing substrate. On the other hand, the full-in-cell type refers to a configuration in which electrodes and the like constituting the detection element are provided only on the substrate that supports the display element. The input / output device of one aspect of the present invention is a full-incell type touch panel. A full-in-cell type touch panel is preferable because it can simplify the configuration of the facing substrate.

Further, in the input / output device of one aspect of the present invention, since the electrodes constituting the display element also serve as the electrodes constituting the detection element, the manufacturing process can be simplified and the manufacturing cost can be reduced, which is preferable.

Further, by applying one aspect of the present invention, the input / output device is made thinner than the configuration in which the separately manufactured display panel and the detection element are bonded together or the configuration in which the detection element is manufactured on the opposite substrate side. Alternatively, the weight can be reduced, or the number of parts of the input / output device can be reduced.

Further, in the input / output device of one aspect of the present invention, both the FPC for supplying the signal for driving the pixel and the FPC for supplying the signal for driving the detection element are arranged on one substrate side. This will result in
It is easy to incorporate into electronic devices, and the number of parts can be reduced. A signal for driving the pixel and a signal for driving the detection element may be supplied by one FPC.

Hereinafter, the configuration of the input / output device according to one aspect of the present invention will be described.

[Cross-sectional configuration example 1 of input / output device]
FIG. 28A shows a cross-sectional view of two adjacent sub-pixels of the input / output device. The two sub-pixels shown in FIG. 28 (A) are sub-pixels possessed by different pixels.

As shown in FIG. 28 (A), the input / output device has the transistor 201a on the substrate 211.
It has a transistor 203a, a liquid crystal element 207a, and the like. Further, an insulating layer such as an insulating layer 212, an insulating layer 213, an insulating layer 215, and an insulating layer 219 is provided on the substrate 211.

For example, by forming one pixel by a sub-pixel exhibiting red, a sub-pixel exhibiting green, and a sub-pixel exhibiting blue, full-color display can be performed on the display unit. The colors exhibited by the sub-pixels are not limited to red, green, and blue. As the pixel, a sub-pixel exhibiting a color such as white, yellow, magenta, or cyan may be used.

The transistor exemplified in the above embodiment can be applied to the transistor 201a included in the sub-pixel.

The liquid crystal element 207a is a liquid crystal element to which the FFS (Fringe Field Switching) mode is applied. The liquid crystal element 207a has a conductive film 251 and a conductive film 252, and a liquid crystal 249. Liquid crystal 2 due to the electric field generated between the conductive film 251 and the conductive film 252.
The orientation of 49 can be controlled. The conductive film 251 can function as a pixel electrode. The conductive film 252 can function as a common electrode.

By using a conductive material that transmits visible light for the conductive film 251 and the conductive film 252, the input / output device can function as a transmissive liquid crystal display device. Further, by using a conductive material that reflects visible light for the conductive film 251 and using a conductive material that transmits visible light for the conductive film 252, the input / output device can function as a reflective liquid crystal display device. Can be done.

Examples of the conductive material that transmits visible light include indium (In), zinc (Zn), and the like.
It is preferable to use a material containing a kind selected from tin (Sn). Specifically, indium oxide, indium tin oxide (ITO: Indium Tin Oxide), indium zinc oxide, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, Examples thereof include indium tin oxide containing titanium oxide, indium tin oxide added with silicon oxide, zinc oxide, and zinc oxide added with gallium. A membrane containing graphene can also be used. The graphene-containing film can be formed, for example, by reducing a film containing graphene oxide formed in the form of a film.

It is preferable to use an oxide conductive film for the conductive film 251. Further, it is preferable to use an oxide conductive film for the conductive film 252. The oxide conductive film preferably has one or more kinds of metal elements contained in the oxide semiconductor film 223. For example, the conductive film 251 preferably contains indium, and In—M—Zn oxide (M is Al, Ti, Ga, Y, Zr, La, Ce, N).
It is more preferably a d, Sn or Hf) film. Similarly, the conductive film 252 preferably contains indium, and more preferably an In—M—Zn oxide film.

At least one of the conductive film 251 and the conductive film 252 may be formed by using an oxide semiconductor. As described above, by using oxide semiconductors having the same metal element for two or more layers among the layers constituting the input / output device, a manufacturing device (for example, a film forming device, a processing device, etc.) can be used in two or more steps. Since it can be used in common in the above, the manufacturing cost can be suppressed.

For example, if a silicon nitride film containing hydrogen is used for the insulating film 253 and an oxide semiconductor is used for the conductive film 251, the conductivity of the oxide semiconductor can be increased by the hydrogen supplied from the insulating film 253.

Examples of the conductive material that reflects visible light include aluminum, silver, and alloys containing these metal materials.

The conductive film 251 that functions as a pixel electrode is electrically connected to the source or drain of the transistor 203a.

The conductive film 252 has a comb-shaped upper surface shape (also referred to as a planar shape) or an upper surface shape provided with slits. An insulating film 253 is provided between the conductive film 251 and the conductive film 252. The conductive film 251 has a portion that overlaps with the conductive film 252 via the insulating film 253. again,
In the region where the conductive film 251 and the colored film 241 overlap, the conductive film 251 has a portion where the conductive film 252 is not arranged.

A conductive film 255 is provided on the insulating film 253. The conductive film 255 is a conductive film 252.
It is electrically connected to the conductive film 252 and can function as an auxiliary wiring for the conductive film 252. By providing the auxiliary wiring electrically connected to the common electrode, it is possible to suppress the voltage drop due to the resistance of the common electrode. Further, at this time, in the case of forming a laminated structure of a conductive film containing a metal oxide and a conductive film containing a metal, it is preferable to form the conductive film by a patterning technique using a halftone mask because the process can be simplified.

The conductive film 255 may be a film having a lower resistance value than the conductive film 252. The conductive film 255
For example, it can be formed in a single layer or laminated using a metal material such as molybdenum, titanium, chromium, tantalum, tungsten, aluminum, copper, silver, neodymium, scandium, or an alloy material containing these elements.

It is preferable that the conductive film 255 is provided at a position overlapping with the light-shielding film 243 or the like so as not to be visually recognized by the user of the input / output device.

The colored film 241 has a portion that overlaps with the liquid crystal element 207a. The light-shielding film 243 has a portion that overlaps with at least one of the transistors 201a and 203a.

The insulating film 245 preferably has a function as an overcoat that prevents impurities contained in the colored film 241 and the light-shielding film 243 from diffusing into the liquid crystal display 249. The insulating film 245 is
If it is not necessary, it may not be provided.

An alignment film may be provided on the surfaces of the substrate 211 and the substrate 261 in contact with the liquid crystal display 249. The alignment film can control the orientation of the liquid crystal 249. For example, FIG. 28 (A)
), An alignment film covering the conductive film 252 may be formed. Further, in FIG. 28A, an alignment film may be provided between the insulating film 245 and the liquid crystal display 249. Further, the insulating film 245 may have both a function as an alignment film and a function as an overcoat.

The input / output device also has a spacer 247. The spacer 247 has a function of preventing the distance between the substrate 211 and the substrate 261 from becoming closer than a certain level.

FIG. 28A shows an example in which the spacer 247 is provided on the insulating film 253 and the conductive film 252, but one aspect of the present invention is not limited to this. The spacer 247 is a substrate 211.
It may be provided on the side or may be provided on the substrate 261 side. For example, the insulating film 2
Spacer 247 may be formed on 45. Further, in FIG. 28A, an example in which the spacer 247 is in contact with the insulating film 253 and the insulating film 245 is shown, but it may not be in contact with the structure provided on either the substrate 211 side or the substrate 261 side. ..

A granular spacer may be used as the spacer 247. As the granular spacer, a material such as silica can be used, but it is preferable to use a material having elasticity such as resin or rubber. At this time, the granular spacer may have a shape that is crushed in the vertical direction.

The substrate 211 and the substrate 261 are bonded together by an adhesive layer (not shown). Board 2
The liquid crystal display 249 is sealed in the area surrounded by 11, the substrate 261 and the adhesive layer.

When the input / output device functions as a transmissive liquid crystal display device, two polarizing plates are arranged so as to sandwich the display unit. The light from the backlight arranged outside the polarizing plate is incident through the polarizing plate. At this time, the orientation of the liquid crystal 249 can be controlled by the voltage applied between the conductive film 251 and the conductive film 252, and the optical modulation of light can be controlled. That is, the intensity of the light emitted through the polarizing plate can be controlled. Further, since the incident light is absorbed by the colored film 241 other than the specific wavelength region, the emitted light is, for example, red, blue, or green.

Further, in addition to the polarizing plate, for example, a circular polarizing plate can be used. As the circular polarizing plate, for example, a linear polarizing plate and a 1/4 wavelength retardation plate laminated can be used. The circular polarizing plate can reduce the viewing angle dependence of the display of the input / output device.

Here, an element to which the FFS mode is applied is used as the liquid crystal element 207a, but the present invention is not limited to this, and a liquid crystal element to which various modes are applied can be used. For example, VA (
Vertical Alignment) mode, TN (Twisted Alignment)
c) Mode, IPS (In-Plane-Switching) mode, ASM (Axi)
ally Symmetric aligned Micro-cell) mode, OC
B (Optically Compensated Birefringence) mode, FLC (Ferroelectric Liquid Crystal) mode, A
A liquid crystal element to which a FLC (AntiFerroductive Liquid Crystal) mode or the like is applied can be used.

Further, a normally black type liquid crystal display device, for example, a transmissive type liquid crystal display device adopting a vertical orientation (VA) mode may be applied to the input / output device. The vertical orientation mode is MV.
A (Multi-Domain Vertical Element) mode, PV
A (Patterned Vertical Alignment) mode, ASV mode and the like can be used.

The liquid crystal element is an element that controls the transmission or non-transmission of light by the optical modulation action of the liquid crystal. The optical modulation action of the liquid crystal is controlled by an electric field applied to the liquid crystal (including a horizontal electric field, a vertical electric field, or an oblique electric field). The liquid crystal used for the liquid crystal element includes a thermotropic liquid crystal, a low molecular weight liquid crystal, a polymer liquid crystal, and a polymer dispersed liquid crystal (PDLC: Po).
lymer Dispersed Liquid Crystal), ferroelectric liquid crystal, antiferroelectric liquid crystal and the like can be used. These liquid crystal materials show a cholesteric phase, a smectic phase, a cubic phase, a chiral nematic phase, an isotropic phase and the like depending on the conditions.

Further, as the liquid crystal material, either a positive type liquid crystal or a negative type liquid crystal may be used, and the optimum liquid crystal material may be used according to the mode and design to which the liquid crystal is applied.

Further, when the transverse electric field method is adopted, a liquid crystal showing a blue phase without using an alignment film may be used. The blue phase is one of the liquid crystal phases, and is a phase that appears immediately before the transition from the cholesteric phase to the isotropic phase when the temperature of the cholesteric liquid crystal is raised. Since the blue phase is expressed only in a narrow temperature range, a liquid crystal composition mixed with 5% by weight or more of a chiral agent is used for the liquid crystal 249 in order to improve the temperature range. A liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent has a short response rate and is optically isotropic. Further, the liquid crystal composition containing the liquid crystal exhibiting the blue phase and the chiral agent does not require an orientation treatment and has a small viewing angle dependence. In addition, since it is not necessary to provide an alignment film, the rubbing process is not required, so that electrostatic breakdown caused by the rubbing process can be prevented, and defects and breakage of the liquid crystal display device during the manufacturing process can be reduced. ..

Here, a substrate that the object to be detected such as a finger or a stylus directly touches may be provided above the substrate 261. At this time, it is preferable to provide a polarizing plate or a circular polarizing plate between the substrate 261 and the substrate. In that case, it is preferable to provide a protective layer (ceramic coat or the like) on the substrate. The protective layer is, for example, silicon oxide, aluminum oxide, yttrium oxide,
Inorganic insulating materials such as yttria-stabilized zirconia (YSZ) can be used. Further, tempered glass may be used for the substrate. As the tempered glass, one that has been physically or chemically treated by an ion exchange method, an air-cooled tempering method, or the like and whose surface is subjected to compressive stress can be used.

In FIG. 28 (A), the conductive film 252 possessed by the left sub-pixel and the conductive film 2 possessed by the right sub-pixel.
The proximity or contact of the object to be detected can be detected by using the capacitance formed between the object and the 52. That is, in the input / output device of one aspect of the present invention, the conductive film 252 serves as both a common electrode of the liquid crystal element and an electrode of the detection element.

As described above, in the input / output device of one aspect of the present invention, since the electrodes constituting the liquid crystal element also serve as the electrodes constituting the detection element, the manufacturing process can be simplified and the manufacturing cost can be reduced. In addition, the input / output device can be made thinner and lighter.

The conductive film 252 is electrically connected to the conductive film 255 which functions as an auxiliary wiring. By providing the conductive film 255, the resistance of the electrode of the detection element can be reduced. By reducing the resistance of the resistance of the electrode of the detection element, the time constant of the electrode of the detection element can be reduced. The smaller the time constant of the electrode of the detection element, the higher the detection sensitivity and the higher the detection accuracy.

Further, if the capacitance between the electrode of the detection element and the signal line is too large, the time constant of the electrode of the detection element may become large. Therefore, it is preferable to provide an insulating film having a flattening function between the transistor and the electrode of the detection element to reduce the capacitance between the electrode of the detection element and the signal line. For example, in FIG. 28A, the insulating layer 219 is provided as an insulating film having a flattening function. By providing the insulating layer 219, the capacitance between the conductive film 252 and the signal line can be reduced. As a result, the time constant of the electrode of the detection element can be reduced. As described above, the smaller the time constant of the electrode of the detection element, the higher the detection sensitivity and the higher the detection accuracy.

For example, the time constant of the electrode of the detection element is larger than 0 seconds and 1 × 10-4 seconds or less, preferably larger than 0 seconds and 5 × 10-5 seconds or less, more preferably larger than 0 seconds and 5 × 10-6 seconds. Below, more preferably greater than 0 seconds and 5 × 10-7 seconds or less, more preferably greater than 0 seconds 2
It is preferable that it is × 10-7 seconds or less. In particular, by setting the time constant to 1 × 10-6 seconds or less, high detection sensitivity can be realized while suppressing the influence of noise.

[Cross-sectional configuration example 2 of input / output device]
FIG. 28B shows a cross-sectional view of two adjacent pixels, which is different from FIG. 28A. Figure 2
The two sub-pixels shown in 8 (B) are sub-pixels possessed by different pixels.

In the configuration example 2 shown in FIG. 28 (B), the stacking order of the conductive film 251 and the conductive film 252, the insulating film 253, and the conductive film 255 is different from that of the configuration example 1 shown in FIG. 28 (A). In addition, in the configuration example 2, the above can be referred to for the same portion as the configuration example 1.

Specifically, the configuration example 2 has the conductive film 255 on the insulating layer 219, the conductive film 252 on the conductive film 255, the insulating film 253 on the conductive film 252, and the insulating film 253. Conductive film 25
Has 1.

Like the liquid crystal element 207b shown in FIG. 28B, the conductive film 251 provided on the upper layer and having a comb-shaped or slit-shaped upper surface shape is used as a pixel electrode, and the conductive film 252 provided on the lower layer is used as a common electrode. You can also do it. Even in that case, the conductive film 251 is the transistor 203a.
It may be electrically connected to the source or drain of.

In FIG. 28B, the conductive film 252 possessed by the left sub-pixel and the conductive film 2 possessed by the right sub-pixel.
The proximity or contact of the object to be detected can be detected by using the capacitance formed between the object and the 52. That is, in the input / output device of one aspect of the present invention, the conductive film 252 serves as both a common electrode of the liquid crystal element and an electrode of the detection element.

In Configuration Example 1 (FIG. 28 (A)), the conductive film 25 that also serves as the electrode of the detection element and the common electrode.
2 is located closer to the display surface side (the side closer to the object to be detected) than the conductive film 251 that functions as a pixel electrode. As a result, the detection sensitivity may be improved in the configuration example 1 as compared with the configuration example 2 in which the conductive film 251 is located closer to the display surface than the conductive film 252.

(Embodiment 9)
In the present embodiment, the display module and the electronic device having the semiconductor device of one aspect of the present invention will be described with reference to FIGS. 29 and 30.

<9-1. Display module>
The display module 8000 shown in FIG. 29 has a touch panel 8004 connected to the FPC 8003, a display panel 8006 connected to the FPC 8005, a backlight 8007, a frame 8009, and a printed circuit board 801 between the upper cover 8001 and the lower cover 8002.
0, has battery 8011.

The semiconductor device of one aspect of the present invention can be used, for example, for the display panel 8006.

The shape and dimensions of the upper cover 8001 and the lower cover 8002 can be appropriately changed according to the sizes of the touch panel 8004 and the display panel 8006.

The touch panel 8004 can be used by superimposing a resistance film type or capacitance type touch panel on the display panel 8006. It is also possible to equip the facing substrate (sealing substrate) of the display panel 8006 with a touch panel function. In addition, the display panel 8
It is also possible to provide an optical sensor in each pixel of 006 to form an optical touch panel.

The backlight 8007 has a light source 8008. Note that FIG. 29 illustrates the configuration in which the light source 8008 is arranged on the backlight 8007, but the present invention is not limited to this. For example, a light source 8008 may be arranged at the end of the backlight 8007, and a light diffusing plate may be used. When a self-luminous light emitting element such as an organic EL element is used, or when a reflective panel or the like is used, the backlight 8007 may not be provided.

In addition to the protective function of the display panel 8006, the frame 8009 has a function as an electromagnetic shield for blocking electromagnetic waves generated by the operation of the printed circuit board 8010. Further, the frame 8009 may have a function as a heat sink.

The printed circuit board 8010 has a power supply circuit, a signal processing circuit for outputting a video signal and a clock signal. The power source for supplying electric power to the power supply circuit may be an external commercial power source or a power source provided by a separately provided battery 8011. The battery 8011 can be omitted when a commercial power source is used.

Further, the display module 8000 may be additionally provided with members such as a polarizing plate, a retardation plate, and a prism sheet.

<9-2. Electronic equipment>
30 (A) to 30 (G) are diagrams showing electronic devices. These electronic devices include a housing 9000, a display unit 9001, a speaker 9003, an operation key 9005 (including a power switch or an operation switch), a connection terminal 9006, and a sensor 9007 (force, displacement, position, speed, etc.).
Measures acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemicals, voice, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared rays. It can have a function), a microphone 9008, and the like.

The electronic devices shown in FIGS. 30A to 30G can have various functions.
For example, a function to display various information (still images, moving images, text images, etc.) on the display unit, a touch panel function, a calendar, a function to display a date or time, and various software (
A function to control processing by a program), a wireless communication function, a function to connect to various computer networks using the wireless communication function, a function to transmit or receive various data using the wireless communication function, and recorded on a recording medium. It can have a function of reading out the program or data being used and displaying it on the display unit. The functions that the electronic devices shown in FIGS. 30A to 30G can have are not limited to these, and can have various functions. Further, although not shown in FIGS. 30 (A) to 30 (H), for electronic devices,
It may be configured to have a plurality of display units. In addition, the electronic device is provided with a camera or the like, a function for shooting a still image, a function for shooting a moving image, a function for saving the shot image on a recording medium (external or built in the camera), and a function for displaying the shot image on the display unit. It may have a function to perform, etc.

The details of the electronic devices shown in FIGS. 30A to 30G will be described below.

FIG. 30A is a perspective view showing the television device 9100. Television device 9
The 100 can incorporate the display unit 9001 into a large screen, for example, a display unit 9001 having a size of 50 inches or more, or 100 inches or more.

FIG. 30B is a perspective view showing a mobile information terminal 9101. The mobile information terminal 9101 has one or more functions selected from, for example, a telephone, a notebook, an information browsing device, and the like. Specifically, it can be used as a smartphone. The mobile information terminal 9101 is
A speaker 9003, a connection terminal 9006, a sensor 9007, and the like may be provided. Further, the mobile information terminal 9101 can display character and image information on a plurality of surfaces thereof. For example, 3
Display unit 9001 with one operation button 9050 (also called an operation icon or simply an icon)
It can be displayed on one side. Further, the information 9051 indicated by the broken line rectangle is displayed on the display unit 900.
It can be displayed on the other side of 1. As an example of the information 9051, a display for notifying an incoming call such as an e-mail, an SNS (social networking service), or a telephone,
There are titles such as e-mail and SNS, sender names such as e-mail and SNS, date and time, time, remaining battery level, antenna reception strength, and the like. Alternatively, the operation button 9050 or the like may be displayed instead of the information 9051 at the position where the information 9051 is displayed.

FIG. 30C is a perspective view showing a mobile information terminal 9102. The mobile information terminal 9102 has a function of displaying information on three or more surfaces of the display unit 9001. Here, information 9052,
An example is shown in which information 9053 and information 9054 are displayed on different surfaces. For example, the user of the mobile information terminal 9102 can check the display (here, information 9053) in a state where the mobile information terminal 9102 is stored in the chest pocket of clothes. Specifically, the telephone number or name of the caller of the incoming call is displayed at a position that can be observed from above the mobile information terminal 9102. The user can check the display and determine whether or not to receive the call without taking out the mobile information terminal 9102 from the pocket.

FIG. 30D is a perspective view showing a wristwatch-type mobile information terminal 9200. The personal digital assistant 9200 can execute various applications such as mobile phone, e-mail, text viewing and creation, music playback, Internet communication, and computer games. Further, the display unit 9001 is provided with a curved display surface, and can display along the curved display surface. Further, the mobile information terminal 9200 can execute short-range wireless communication standardized for communication. For example, by communicating with a headset capable of wireless communication, it is possible to make a hands-free call. Further, the mobile information terminal 9200 has a connection terminal 9006, and can directly exchange data with another information terminal via a connector. It is also possible to charge via the connection terminal 9006. The charging operation is the connection terminal 900.
It may be performed by wireless power supply without going through 6.

30 (E), (F), and (G) are perspective views showing a foldable mobile information terminal 9201. Further, FIG. 30 (E) is a perspective view showing a state in which the mobile information terminal 9201 is deployed, and is a perspective view of FIG. 30.
(F) is a perspective view of a state in which the mobile information terminal 9201 is in the process of being changed from one of the expanded state or the folded state to the other, and FIG. 30 (G) is a perspective view of the mobile information terminal 9201 in the folded state. be. The mobile information terminal 9201 is excellent in portability in the folded state, and is excellent in the listability of the display due to the wide seamless display area in the unfolded state. Mobile information terminal 92
The display unit 9001 included in the 01 has three housings 9000 connected by a hinge 9055.
Is supported by. By bending between the two housings 9000 via the hinge 9055, the mobile information terminal 9201 can be reversibly deformed from the unfolded state to the folded state. For example, the mobile information terminal 9201 can be bent with a radius of curvature of 1 mm or more and 150 mm or less.

The electronic device described in the present embodiment is characterized by having a display unit for displaying some information. However, the semiconductor device of one aspect of the present invention can also be applied to an electronic device having no display unit.

The configuration shown in this embodiment can be used in combination with the configurations shown in other embodiments as appropriate.

102 Substrate 104 Insulation film 106 Conductive film 108 Oxide semiconductor film 108_1 Layer 108_2 Layer 108_3 Layer 108d Drain region 108i Channel region 108s Source region 110 Insulation film 110_0 Insulation film 112 Oxide semiconductor film 112_Oxide semiconductor film 116 Insulation film 117 Insulation film 118 Insulation film 120 Conductive 120a Conductive 120b Conductive 140 Mask 141a Opening 141b Opening 143 Opening 145 Impure element 150 Transistor 150A Transistor 150B Transistor 160 Transistor 160A Transistor 160B Transistor 170 Transistor 201a Transistor 203a Transficit 207a Liquid crystal element 207b 211 Substrate 212 Insulation layer 213 Insulation layer 215 Insulation layer 219 Insulation layer 223 Oxide semiconductor film 241 Colored film 243 Light-shielding film 245 Insulation film 247 Spacer 249 Liquid crystal 251 Conductive 252 Conductive 253 Insulation film 255 Conductive 261 Substrate 501 Pixel circuit 502 Pixel part 504 Drive circuit part 504a Gate driver 504b Source driver 506 Protection circuit 507 Terminal part 550 Transistor 552 Transistor 554 Transistor 560 Capacitive element 562 Capacitive element 570 Liquid crystal element 571 Light emitting element 700 Display device 701 Board 702 Pixel part 704 Source driver circuit unit 705 Board 706 Gate driver Circuit part 708 FPC terminal part 710 Signal line 711 Wiring part 712 Sealing material 716 FPC
730 Insulation film 732 Encapsulation film 734 Insulation film 736 Coloring film 738 Light-shielding film 750 Transistor 752 Transistor 760 Connection electrode 770 Flattening insulation film 772 Conduction 774 Conduction 775 Liquid crystal element 767 Liquid crystal layer 778 Structure 780 Anisotropic conductive film 782 Light emitting element 784 Conductive 786 EL layer 788 Conductive element 800 Capacitive element 800 Inverter 810 OS transistor 820 OS transistor 831 Signal waveform 832 Signal waveform 840 Broken line 841 Solid line 850 OS transistor 860 CMOS inverter 1280a p-type transistor 1280b n-type transistor 1280c n-type transistor 1281 Capacitive element 1282 Transistor 1311 Transistor 1312 Wiring 1313 Wiring 1314 Wiring 1315 Wiring 1316 Wiring 1317 Wiring 1351 Transistor 1352 Transistor 1353 Transistor 1354 Transistor 1360 Photoconverter 1401 Signal 1402 Signal 1403 Signal 1404 Signal 1405 Signal 8000 Display module 8001 8003 FPC
8004 touch panel 8005 FPC
8006 Display panel 8007 Backlight 8008 Light source 8009 Frame 8010 Print board 8011 Battery 9000 Housing 9001 Display 9003 Speaker 9005 Operation key 9006 Connection terminal 9007 Sensor 9008 Microphone 9050 Operation button 9051 Information 9052 Information 9053 Information 9054 Information 9055 Hing 9100 Television device 9101 Mobile information terminal 9102 Mobile information terminal 9200 Mobile information terminal 9201 Mobile information terminal

Claims (1)

A semiconductor device with transistors
The transistor is
The first gate electrode and
The first gate insulating film on the first gate electrode and
The first oxide semiconductor film on the first gate insulating film and
The second oxide semiconductor film on the first oxide semiconductor film and
The second gate insulating film on the second oxide semiconductor film and
With the second gate electrode on the second gate insulating film,
The insulating film on the second gate electrode and
It has a source electrode and a drain electrode,
The second oxide semiconductor film is in contact with the upper surface and the side surface of the first oxide semiconductor film.
The insulating film is in contact with the upper surface of the second gate electrode and is in contact with the upper surface.
Each of the source electrode and the drain electrode is in contact with the side surface of the insulating film, the side surface of the second gate insulating film, and the side surface of the second oxide semiconductor film .
The second gate electrode is a semiconductor device having an oxide semiconductor.

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