JP2022070860A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device including a capacitive element that has a high aperture ratio and is capable of increasing a capacitance value, and also to provide the semiconductor device low in manufacturing cost.

SOLUTION: A semiconductor device includes: a transistor including a first oxide semiconductor film and a second oxide semiconductor film; and a capacitive element including an insulation film between a pair of electrodes. The transistor includes: the first oxide semiconductor film; a gate insulation film provided in contact with the first oxide semiconductor film; the second oxide semiconductor film provided in contact with the gate insulation film and provided at a position that overlaps with the first oxide semiconductor film; and a source electrode and a drain electrode which are connected to the first oxide semiconductor film. One of the pair of electrodes of the capacitive element is provided on the same surface as the second oxide semiconductor film.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a product, a method, or a manufacturing method. Alternatively, the present invention is a process, a machine,
Regarding manufacturing or composition (composition of matter). One aspect of the present invention relates to a semiconductor device, a display device, an electronic device, a method for manufacturing the same, or a method for driving the same. In particular, one aspect of the present invention relates to, for example, a semiconductor device including a transistor and a capacitive element.

Transistors used in many flat panel displays such as liquid crystal displays and light emitting display devices are composed of silicon semiconductors such as amorphous silicon, single crystal silicon, and polysilicon that are formed on a glass substrate. .. Transistors using the silicon semiconductor are also used in integrated circuits (ICs) and the like.

In recent years, a technique of using a metal oxide exhibiting semiconductor characteristics for a transistor instead of a silicon semiconductor has attracted attention. In the present specification, a metal oxide exhibiting semiconductor characteristics is referred to as an oxide semiconductor. For example, as an oxide semiconductor, zinc oxide or In-Ga-
A technique for producing a transistor using a Zn-based oxide and using the transistor as a switching element for pixels of a display device is disclosed (see Patent Document 1 and Patent Document 2).

Further, in order to increase the aperture ratio, the oxide semiconductor film provided on the same surface as the oxide semiconductor film of the transistor and the pixel electrode connected to the transistor are provided with a capacitive element separated by a predetermined distance. A display device is disclosed (see Patent Document 3).

Japanese Unexamined Patent Publication No. 2007-123861 Japanese Unexamined Patent Publication No. 2007-96055 US Pat. No. 8,102,476

A dielectric film is provided between a pair of electrodes in a capacitive element, and at least one of the pair of electrodes is formed of a light-shielding conductive film such as a gate electrode, a source, or a drain constituting the transistor. I often do it.

Further, in order to increase the capacitance value of the capacitive element, there is a means of increasing the occupied area of the capacitive element, specifically, increasing the area on which the pair of electrodes are superimposed. However,
In the display device, if the area of the conductive film having a light-shielding property is increased in order to increase the area where the pair of electrodes are superimposed, the aperture ratio of the pixels is reduced and the display quality of the image is deteriorated.

Therefore, in view of the above problems, one of the problems of the present invention is to provide a semiconductor device having a capacitive element having a high aperture ratio and capable of increasing the capacitive value. also,
One of the challenges is to provide semiconductor devices with low manufacturing costs. Alternatively, one of the issues is to provide a new semiconductor device or the like.

The description of these issues does not preclude the existence of other issues. It should be noted that one aspect of the present invention does not need to solve all of these problems. Issues other than these are self-evident from the description of the description, drawings, claims, etc.
It is possible to extract problems other than these from the drawings, claims, and the like.

One aspect of the present invention is a semiconductor device including a transistor including a first oxide semiconductor film, a second oxide semiconductor film, and a capacitive element including an insulating film between a pair of electrodes. The transistor is provided in contact with the first oxide semiconductor film, the gate insulating film provided in contact with the first oxide semiconductor film, and the gate insulating film, and is superposed on the first oxide semiconductor film. It has a second oxide semiconductor film provided in the above, a source electrode and a drain electrode connected to the first oxide semiconductor film, and one of the pair of electrodes of the capacitive element is a second oxide. It is a semiconductor device characterized in that it is provided on the same surface as the semiconductor film.

Further, another aspect of the present invention is a semiconductor device having a transistor including a first oxide semiconductor film, a second oxide semiconductor film, and a capacitive element including an insulating film between a pair of electrodes. The transistor is a gate electrode including a second oxide semiconductor film, a gate insulating film on the gate electrode, and a first oxide semiconductor film at a position superimposing on the gate electrode on the gate insulating film. 1st
A semiconductor device comprising a source electrode and a drain electrode on an oxide semiconductor film of the above, wherein one of a pair of electrodes of the capacitive element is provided on the same surface as the second oxide semiconductor film. be.

Further, another aspect of the present invention is a semiconductor device including a transistor including a first oxide semiconductor film, a second oxide semiconductor film, and a capacitive element including an insulating film between a pair of electrodes. The transistor is a first oxide semiconductor film, a source electrode and a drain electrode on the first oxide semiconductor film, a gate insulating film on the first oxide semiconductor film, and a gate insulating film. It has a gate electrode including a second oxide semiconductor film at a position overlapping with the first oxide semiconductor film of the above, and one of the pair of electrodes of the capacitive element has the same surface as the second oxide semiconductor film. It is a semiconductor device characterized by being provided on the top.

Further, in each of the above configurations, it is preferable that the other of the pair of electrodes of the capacitive element is provided on the same surface as the first oxide semiconductor film. Further, it is preferable that the capacitive element has translucency in visible light.

Further, in each of the above configurations, the first oxide semiconductor film and the second oxide semiconductor film are In.
-M-Zn oxide (M is Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn or H
(Representing f) is preferable.

Further, a display device and an electronic device using the semiconductor device having each of the above configurations are also included in one aspect of the present invention.

According to one aspect of the present invention, it is possible to provide a semiconductor device having a capacitive element having a high aperture ratio and capable of increasing a capacitive value. Further, it is possible to provide a semiconductor device having a low manufacturing cost. Alternatively, a new semiconductor device or the like 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.

Top view and sectional view showing one aspect of a semiconductor device. The cross-sectional view which shows one aspect of the manufacturing method of a semiconductor device. The cross-sectional view which shows one aspect of the manufacturing method of a semiconductor device. Top view and sectional view showing one aspect of a semiconductor device. The cross-sectional view which shows one aspect of the manufacturing method of a semiconductor device. The cross-sectional view which shows one aspect of the manufacturing method of a semiconductor device. Top view and sectional view showing one aspect of a semiconductor device. Top view and sectional view showing one aspect of a semiconductor device. The cross-sectional view which shows one aspect of the manufacturing method of a semiconductor device. The cross-sectional view which shows one aspect of the manufacturing method of a semiconductor device. A cross-sectional view and a band diagram showing one form of a semiconductor device. A block diagram and a circuit diagram illustrating a display device. The figure explaining the display module. The figure explaining the electronic device. The cross-sectional view which shows one aspect of the semiconductor device. The cross-sectional view which shows one aspect of the semiconductor device. Top view and sectional view showing one aspect of a semiconductor device. Top view and sectional view showing one aspect of a semiconductor device. The cross-sectional view which shows one aspect of the semiconductor device. The cross-sectional view which shows one aspect of the semiconductor device. The cross-sectional view which shows one aspect of the semiconductor device. The cross-sectional view which shows one aspect of the semiconductor device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, one aspect of the present invention is not limited to the following description, and it is easily understood by those skilled in the art that the form and details thereof can be variously changed without departing from the gist of the present invention and its scope. To. Therefore, one aspect of the present invention is not construed as being limited to the description of the embodiments shown below.
Further, in the embodiments described below, the same reference numerals or the same hatch patterns are commonly used among different drawings for the same parts or parts having the same functions, and the repeated description thereof will be omitted.

In each of the figures described herein, the size, film thickness, or region of each configuration may be exaggerated for clarity. Therefore, it is not necessarily limited to that scale.

Further, the first and second ordinal numbers used in the present specification and the like are attached to avoid mixing of the components, and are not limited numerically. Therefore, for example, the "first" can be appropriately replaced with the "second" or "third" for explanation.

The "source" and "drain" functions of the transistor may be interchanged when a transistor having a different polarity is used or when the direction of the current changes in the circuit operation. Therefore, in the present specification, the terms "source" and "drain" may be used interchangeably.

(Embodiment 1)
In the present embodiment, the semiconductor device of one aspect of the present invention will be described with reference to FIGS. 1 to 3.

<Semiconductor device configuration example>
1 (A) is a top view of the semiconductor device of one aspect of the present invention, and FIG. 1 (B) is FIG. 1 (A).
) Corresponds to the cross-sectional view of the cut surface between the alternate long and short dash line AB and between the alternate long and short dash line CD. In addition, in FIG. 1A, in order to avoid complication, a part of the components (gate insulating film and the like) of the semiconductor device is omitted.

The semiconductor device shown in FIGS. 1A and 1B has a transistor 150 including a first oxide semiconductor film 110a and a second oxide semiconductor film 104a, and a capacitance including an insulating film between a pair of electrodes. It has an element 160 and. In the capacitive element 160, one of the pair of electrodes is the second oxide semiconductor film 104b on the same plane as the second oxide semiconductor film 104a, and the other of the pair of electrodes is the first oxide semiconductor film. It is the first oxide semiconductor film 110b on the same plane as 110a.

The transistor 150 includes a gate electrode including a second oxide semiconductor film 104a on the substrate 102, an insulating film 108 functioning as a gate insulating film on the gate electrode including the second oxide semiconductor film 104a, and an insulating film 108. It has a first oxide semiconductor film 110a at a position overlapping with the gate electrode including the second oxide semiconductor film 104a above, and a source electrode 112a and a drain electrode 112b on the first oxide semiconductor film 110a. In other words, transistor 150
Is provided in contact with the first oxide semiconductor film 110a, the insulating film 108 functioning as a gate insulating film provided in contact with the first oxide semiconductor film 110a, and the insulating film 108, and is the first oxidation. A second oxide semiconductor film 104a provided at a position superimposing on the object semiconductor film 110a, and
Source electrode 112a and drain electrode 112 connected to the first oxide semiconductor film 110a
With b. The transistor 150 shown in FIGS. 1A and 1B has a so-called bottom gate structure.

The first oxide semiconductor film 110a functions as a channel region of the transistor 150. Further, the second oxide semiconductor film 104a functions as a gate electrode of the transistor 150. Therefore, the second oxide semiconductor film 104 rather than the first oxide semiconductor film 110a
The resistivity of a is low. Further, the first oxide semiconductor film 110a and the second oxide semiconductor film 104
It is preferable that a has the same metal element. By configuring the first oxide semiconductor film 110a and the second oxide semiconductor film 104a to have the same metal element, it is possible to commonly use manufacturing equipment (for example, film forming equipment, processing equipment, etc.). Therefore, the manufacturing cost can be suppressed.

Therefore, the transistor 150 is in contact with the first oxide semiconductor film 110a, the insulating film 108 in contact with the first oxide semiconductor film 110a, and the position where the transistor 150 is in contact with the insulating film 108 and overlaps with the first oxide semiconductor film 110a. It has a second oxide semiconductor film 104a, and the first oxide semiconductor film 110a and the second oxide semiconductor film 104a have the same metal element and are from the first oxide semiconductor film 110a. However, the resistance of the second oxide semiconductor film 104a is low.

Further, wiring or the like separately formed of a metal film or the like may be connected to the second oxide semiconductor films 104a and 104b. For example, when the semiconductor device shown in FIG. 1 is used for a transistor and a capacitive element in the pixel portion of a display device, a routing wiring, a gate wiring, or the like is formed of a metal film, and a second oxide semiconductor film 104a is formed on the metal film. A configuration in which 104b is connected may be used. By forming the routing wiring, the gate wiring, or the like with a metal film, it is possible to reduce the wiring resistance, so that it is possible to suppress signal delay and the like.

Further, on the transistor 150, more specifically, the insulating films 114, 116 and 118 are formed on the first oxide semiconductor film 110a, the source electrode 112a and the drain electrode 112b. The insulating films 114, 116, and 118 have a function as a protective insulating film for the transistor 150.

The capacitive element 160 has a function as one of the pair of electrodes on the substrate 102.
The oxide semiconductor film 104b of the above, the insulating film 108 functioning as a dielectric film on the second oxide semiconductor film 104b, and a pair of positions superposed on the second oxide semiconductor film 104b via the insulating film 108. It has a first oxide semiconductor film 110b, which has a function as the other electrode of the electrode. Further, an insulating film 118 having a function as a protective insulating film is formed on the capacitive element 160, more specifically, on the first oxide semiconductor film 110b.

As described above, the insulating film 108 functions as a gate insulating film in the transistor 150 and as a dielectric film in the capacitive element 160. Further, in the present embodiment, the insulating film 108 is a laminated structure of the insulating film 106 and the insulating film 107. However, one aspect of the present invention is not limited to this, and the insulating film 108 may have a single-layer structure or a laminated structure having three or more layers.

Further, the capacitive element 160 has translucency. That is, the first capacitance element 160 has.
The oxide semiconductor film 110b, the second oxide semiconductor film 104b, and the insulating film 108 are each made of a translucent material. In this way, since the capacitive element 160 has translucency, it can be formed large (in a large area) in a region other than the portion where the transistor is formed in the pixel, so that the capacitive value can be increased while increasing the aperture ratio. An increased semiconductor device can be obtained. As a result, a semiconductor device having excellent display quality can be obtained. Further, the capacitive element 16
As 0, it can be manufactured by using the manufacturing process of the transistor 150. therefore,
It is possible to obtain a semiconductor device having a low manufacturing cost.

As the insulating film 106 used for the transistor 150 and the capacitive element 160, and the insulating film 118 provided on the transistor 150 and the capacitive element 160, an insulating film containing at least hydrogen is used. Further, the insulating film 10 used for the transistor 150 and the capacitive element 160
7. Insulating films 114 and 116 provided on the transistor 150 and the capacitive element 160.
As an insulating film containing at least oxygen, an insulating film is used. As described above, by using the insulating film used for the transistor 150 and the capacitive element 160 and the insulating film used on the transistor 150 and the capacitive element 160 as the insulating film having the above-described configuration, the first insulating film of the transistor 150 and the capacitive element 160 has. The resistance of the oxide semiconductor film and the second oxide semiconductor film can be controlled.

Specifically, in the transistor 150, since the first oxide semiconductor film 110a is used as a channel region, the first oxide semiconductor film 110b and the second oxide semiconductor film 104
The resistivity is higher than that of a and 104b. On the other hand, the first oxide semiconductor film 110b and the second
Since the oxide semiconductor films 104a and 104b of No. 1 have a function as electrodes, the resistivity is lower than that of the first oxide semiconductor film 110a.

Here, the first oxide semiconductor films 110a and 110b, and the second oxide semiconductor film 104.
The method of controlling the resistivity of a and 104b will be described below.

<Method of controlling resistivity of oxide semiconductor>
The first oxide semiconductor films 110a and 110b, and the second oxide semiconductor films 104a and 10
The oxide semiconductor film that can be used in 4b is a semiconductor material whose resistivity can be controlled by oxygen deficiency in the film and / or the concentration of impurities such as hydrogen and water in the film. for that reason,
The first oxide semiconductor films 110a and 110b, and the second oxide semiconductor films 104a and 104.
By selecting a treatment for increasing the oxygen deficiency and / or the impurity concentration to b, or a treatment for reducing the oxygen deficiency and / or the impurity concentration, the resistivity of each oxide semiconductor film formed in the same step is controlled. be able to.

Specifically, the second oxide semiconductor film 1 that functions as the gate electrode of the transistor 150.
04a, the oxide semiconductor film used for the second oxide semiconductor film 104b functioning as the electrode of the capacitive element 160 and the first oxide semiconductor film 110b functioning as the electrode of the capacitive element 160 is subjected to plasma treatment to oxidize the oxide semiconductor film. By increasing oxygen deficiency in the film of a physical semiconductor and / or increasing impurities such as hydrogen and water in the film of an oxide semiconductor, an oxide semiconductor film having a high carrier density and a low resistance is obtained. Can be done. Further, an oxide semiconductor film having a high carrier density and a low resistance is formed by contacting an insulating film containing hydrogen with an oxide semiconductor film and diffusing hydrogen from the insulating film containing hydrogen to the oxide semiconductor film. Can be.

On the other hand, the first oxide semiconductor film 110 that functions as a channel region of the transistor 150.
a is an insulating film 106 containing hydrogen by providing the insulating films 107, 114, 116.
The configuration is such that it does not come into contact with 118. Oxygen is supplied to the first oxide semiconductor film 110a by applying an insulating film containing oxygen to at least one of the insulating films 107, 114, and 116, in other words, an insulating film capable of releasing oxygen. can do. The first oxide semiconductor film 110a to which oxygen is supplied becomes an oxide semiconductor film having a high resistivity by compensating for oxygen deficiency in the film or at the interface. Examples of the insulating film capable of releasing oxygen include a silicon oxide film.
Alternatively, a silicon oxide film can be used.

Further, in order to obtain an oxide semiconductor film having a low resistance, hydrogen, boron, phosphorus or nitrogen is injected into the oxide semiconductor film by using an ion implantation method, an ion doping method, a plasma implantation ion implantation method or the like. You may.

Further, in order to obtain an oxide semiconductor film having a low resistivity, the oxide semiconductor film may be subjected to plasma treatment. For example, the plasma treatment is typically a noble gas (He, Ne, A).
Plasma treatment using a gas containing one selected from r, Kr, Xe), hydrogen, and nitrogen can be mentioned. More specifically, plasma treatment in an Ar atmosphere, plasma treatment in an Ar and hydrogen mixed gas atmosphere, plasma treatment in an ammonia atmosphere, plasma treatment in an Ar and ammonia mixed gas atmosphere, or nitrogen. Plasma treatment in an atmosphere can be mentioned.

By the above plasma treatment, the oxide semiconductor film forms an oxygen deficiency in the oxygen-desorbed lattice (or the oxygen-desorbed portion). The oxygen deficiency may be a factor in generating carriers. Further, when hydrogen is supplied from the vicinity of the oxide semiconductor film, more specifically, from the insulating film in contact with the lower side or the upper side of the oxide semiconductor film, when the oxygen deficiency and hydrogen are combined, electrons that are carriers are used. May be generated.

On the other hand, the oxide semiconductor film in which the oxygen deficiency is compensated and the hydrogen concentration is reduced is highly pure and intrinsic.
Alternatively, it can be said that it is an oxide semiconductor film that has been substantially purified. Here, what is practically true?
The carrier density of the oxide semiconductor film is less than 1 × 10 ¹⁷ / cm ³ , preferably less than 1 × 10 ¹³ / cm ³ , and more preferably 1 × 10 ^-9 / cm ³ or more. 1 × 10 ¹¹ pieces / cm It means that it is less than ³ . Oxide semiconductor films having high-purity intrinsics or substantially high-purity intrinsics have few carrier sources, so that the carrier density can be lowered. 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 can be reduced.

Further, an oxide semiconductor film having high-purity intrinsic or substantially high-purity intrinsic has a remarkably small off-current, and even if it is an element having a channel width of 1 × ¹⁰⁶ μm and a channel length of L of 10 μm, it can be used as a source electrode. When the voltage between the drain electrodes (drain voltage) is in the range of 1 V to 10 V, it is possible to obtain the characteristic that the off current is not more than the measurement limit of the semiconductor parameter analyzer, that is, 1 × 10 ^-13 A or less. Therefore, the transistor 150 using the first oxide semiconductor film 110a using the oxide semiconductor film having the above-mentioned high-purity intrinsic or substantially high-purity intrinsic in the channel region has small fluctuation in electrical characteristics and high reliability. It becomes a transistor.

As the insulating film 106, for example, an insulating film containing hydrogen, in other words, an insulating film capable of releasing hydrogen, typically a silicon nitride film, is used to provide a second oxide semiconductor film 104a.
, 104b can be supplied with hydrogen. Further, as the insulating film 118, for example, by using an insulating film containing hydrogen as in the insulating film 106, hydrogen can be supplied to the first oxide semiconductor film 110b. As the insulating film capable of releasing hydrogen, it is preferable that the concentration of hydrogen contained in the film is 1 × 10 ²² atoms / cm ³ or more. By forming such an insulating film in contact with the second oxide semiconductor films 104a, 104b and the first oxide semiconductor film 110b, the second oxide semiconductor films 104a, 104b and the first oxide semiconductor are formed. Membrane 110
Hydrogen can be effectively contained in b. As described above, the second oxide semiconductor film 104
The resistivity of the oxide semiconductor film can be controlled by changing the configuration of the insulating film in contact with a, 104b and the first oxide semiconductor film 110b.

The hydrogen contained in the oxide semiconductor film reacts with oxygen bonded to a metal atom to become water, and at the same time, forms an oxygen deficiency in the oxygen-desorbed lattice (or the oxygen-desorbed portion). When hydrogen enters the oxygen deficiency, electrons that are carriers may be generated. In addition, a part of hydrogen may be bonded to oxygen, which is bonded to a metal atom, to generate an electron as a carrier.
Therefore, the second oxide semiconductor film 104 provided in contact with the insulating film containing hydrogen
The a, 104b and the first oxide semiconductor film 110b are oxide semiconductor films having a higher carrier density than the first oxide semiconductor film 110a.

It is preferable that hydrogen is reduced as much as possible in the first oxide semiconductor film 110a in which the channel region of the transistor 150 is formed. Specifically, the first oxide semiconductor film 11
At 0a, secondary ion mass spectrometry (SIMS: Secondary Ion Mass)
The hydrogen concentration obtained by s Spectrometry) is 2 × 10 ²⁰ atoms /
cm ³ or less, preferably 5 × 10 ¹⁹ atoms / cm ³ or less, more preferably 1 × 10
¹⁹ atoms / cm ³ or less, 5 × 10 ¹⁸ atoms / cm less than ³ , preferably 1 × 1
0 ¹⁸ atoms / cm ³ or less, more preferably 5 × 10 ¹⁷ atoms / cm ³ or less,
More preferably, it is 1 × 10 ¹⁶ atoms / cm ³ or less.

On the other hand, a second function that functions as a gate electrode of the transistor 150 and an electrode of the capacitive element 160.
The oxide semiconductor films 104a and 104b of the above and the oxide semiconductor film 110b functioning as an electrode of the capacitive element 160 have a higher hydrogen concentration and / or an oxygen deficiency amount and a lower resistance than the first oxide semiconductor film 110a. It is an oxide semiconductor film.

Further, the first oxide semiconductor films 110a and 110b and the second oxide semiconductor films 104a,
104b has the same metal element. It is preferable that the first oxide semiconductor films 110a and 110b and the second oxide semiconductor films 104a and 104b have the same metal element because the manufacturing cost can be reduced. However, the first oxide semiconductor films 110a and 110b
And, even if the second oxide semiconductor films 104a and 104b have the same metal element, the composition may be different. For example, during the manufacturing process of a transistor and a capacitive element, the metal element in the film may be desorbed to have a different metal composition.

As described above, in the semiconductor device of one aspect of the present invention, the conductive film that functions as the gate electrode of the transistor and the conductive film that functions as the electrode of the capacitive element are simultaneously formed, in other words, the conductive film functions as the gate electrode of the transistor. By forming the conductive film to be formed and the conductive film functioning as electrodes of the capacitive element on the same surface, it is possible to reduce the manufacturing cost. also,
The conductive film that functions as the gate electrode of the transistor and the conductive film that functions as the electrode of the capacitive element are configured to include an oxide semiconductor film. By appropriately treating the oxide semiconductor film,
A conductive film having a low resistivity and a translucent property can be obtained. By using the conductive film, translucency can be imparted to the transistor and / or the capacitive element.

Here, details of other components of the semiconductor device shown in FIGS. 1A and 1B will be described below.

<Board>
There are no major restrictions on the material of the substrate 102, but at least it must have heat resistance sufficient to withstand the subsequent heat treatment. For example, a glass substrate, a ceramic substrate, a quartz substrate, a sapphire substrate, or the like may be used as the substrate 102. Further, it is also possible to apply a single crystal semiconductor substrate made of silicon or silicon carbide, a polycrystalline semiconductor substrate, a compound semiconductor substrate such as silicon germanium, an SOI substrate, or the like, and a semiconductor element is provided on these substrates. May be used as the substrate 102. When a glass substrate is used as the substrate 102, the 6th generation (1500 mm × 1850 mm) and the 7th generation (1870 mm × 220) are used.
0 mm), 8th generation (2200 mm x 2400 mm), 9th generation (2400 mm x 280)
By using a large area substrate such as 0 mm), 10th generation (2950 mm × 3400 mm), etc.
A large display device can be manufactured. Further, a flexible substrate is used as the substrate 102.
The transistor 150, the capacitive element 160, and the like may be formed directly on the flexible substrate.

In addition to these, various substrates can be used as the substrate 102 to form transistors. The type of substrate is not limited to a specific one. Examples of the substrate include a plastic substrate, a metal substrate, a stainless still substrate, a substrate having a stainless still foil, a tungsten substrate, a substrate having a tungsten foil, and a flexible substrate.
There are laminated films, papers containing fibrous materials, base films, and the like. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, and soda lime glass. As an example of a flexible substrate, polyethylene terephthalate (PE)
There are flexible synthetic resins such as T), polyethylene naphthalate (PEN), plastics typified by polyether sulfone (PES), and acrylics. Examples of the laminated film include polypropylene, polyester, polyvinyl fluoride, polyvinyl chloride and the like. Examples of the base film include polyester, polyamide, polyimide, inorganic vapor-deposited film, paper and the like. In particular, by manufacturing a transistor using a semiconductor substrate, 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, or shape. .. 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.

A transistor may be formed using a certain substrate, then the transistor may be transposed to another substrate, and the transistor may be arranged on another substrate. As an example of the substrate on which the transistor is translocated, in addition to the substrate capable of forming the above-mentioned transistor, a paper substrate, a cellophane substrate, a stone substrate, a wood substrate, a cloth substrate (natural fiber (silk, cotton, linen), etc. 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 oxide semiconductor film and second oxide semiconductor film>
The first oxide semiconductor films 110a and 110b, and the second oxide semiconductor films 104a and 10
4b is at least indium (In), zinc (Zn) and M (Al, Ti, Ga, Y,
It is preferable to include a film represented by an In—M—Zn oxide containing (a metal such as Zr, La, Ce, Sn or Hf). Alternatively, it is preferable to include both In and Zn. Further, in order to reduce variations in the electrical characteristics of the transistor using the oxide semiconductor, it is preferable to include a stabilizer together with them.

Stabilizers include, for example, gallium (Ga), tin (Sn), hafnium (Hf), aluminum (Al), or zirconium (Zr), including the metals described in M above.
And so on. Another stabilizer is lanthanum (La), which is a lanthanoid.
, Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Samarium (Sm),
Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (
Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu) and the like.

The first oxide semiconductor films 110a and 110b, and the second oxide semiconductor films 104a and 10
Examples of the oxide semiconductor constituting 4b include In—Ga—Zn-based oxide and In—Al—.
Zn-based oxide, In-Sn-Zn-based oxide, In-Hf-Zn-based oxide, In-La-Z
n-based oxide, In-Ce-Zn-based oxide, In-Pr-Zn-based oxide, In-Nd-Zn
In -Ho-Zn-based oxide, In-Er-Zn-based oxide, In-Tm-Zn-based oxide, In-Yb-Zn-based oxide, In-Lu-Zn-based oxide, In-Sn-Ga- Zn-based oxide, In-Hf-Ga-
Zn-based oxide, In-Al-Ga-Zn-based oxide, In-Sn-Al-Zn-based oxide, I
An n—Sn—Hf—Zn-based oxide and an In—Hf-Al—Zn-based oxide can be used.

Here, the In—Ga—Zn-based oxide means an oxide containing In, Ga, and Zn as main components, and the ratio of In, Ga, and Zn does not matter. In, Ga, and Z
A metal element other than n may be contained.

Further, the first oxide semiconductor films 110a and 110b and the second oxide semiconductor films 104a,
104b has the same metal element among the above oxides. First oxide semiconductor film 110
By using the a and 110b and the second oxide semiconductor films 104a and 104b as the same metal element, the manufacturing cost can be reduced. For example, the manufacturing cost can be reduced by using a metal oxide target having the same metal composition. Further, by using a metal oxide target having the same metal composition, an etching gas or an etching solution for processing an oxide semiconductor film can be commonly used.

<Insulating film>
The insulating films 106 and 107 that function as the gate insulating film of the transistor 150 and the dielectric film of the capacitive element 160 include a silicon oxide film, a silicon oxide film, a silicon nitride film, and nitrided by a plasma CVD method, a sputtering method, or the like. An insulating layer containing one or more of a silicon film, an aluminum oxide film, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, and a neodymium oxide film. Each can be used. The insulating films 106 and 10
Instead of the laminated structure of 7, a single insulating layer selected from the above-mentioned materials may be used.

The first oxide semiconductor film 110 that functions as the channel region of the transistor 150.
The insulating film 107 in contact with a is preferably an oxide insulating film, and more preferably has a region containing oxygen in excess of the stoichiometric composition (oxygen excess region). In other words
The insulating film 107 is an insulating film capable of releasing oxygen. In order to provide the oxygen excess region in the insulating film 107, for example, the insulating film 107 may be formed in an oxygen atmosphere. Alternatively, oxygen may be introduced into the insulating film 107 after the film formation to form an oxygen excess region. As a method for introducing oxygen, an ion implantation method, an ion doping method, a plasma implantation ion implantation method, a plasma treatment, or the like can be used.

Further, when hafnium oxide is used as the insulating films 106 and 107, the following effects are obtained. Hafnium oxide has a higher relative permittivity than silicon oxide and silicon nitride. Therefore, since the physical film thickness can be made larger than the equivalent oxide film thickness, the equivalent oxide film thickness is 10 n.
Even when it is set to m or less or 5 nm or less, the leakage current due to the tunnel current can be reduced. That is, it is possible to realize a transistor having a small off-current. Further, hafnium oxide having a crystal structure has a higher relative permittivity than hafnium oxide having an amorphous structure. Therefore, it is preferable to use hafnium oxide having a crystal structure in order to obtain a transistor having a small off-current. Examples of the crystal structure include a monoclinic system and a cubic system. However, one aspect of the present invention is not limited to these.

In this embodiment, a silicon nitride film is formed as the insulating film 106, and the insulating film 107 is formed.
As a silicon oxide film is formed. Since the silicon nitride film has a higher relative permittivity than the silicon oxide film and the film thickness required to obtain the same capacitance as the silicon oxide film is large, the gate insulating film of the transistor 150 and the capacitive element 160 Insulating film 108 that functions as a dielectric film
As a result, the insulating film can be physically thickened by including the silicon nitride film. Therefore, it is possible to suppress a decrease in the withstand voltage of the transistor 150 and the capacitive element 160, and further improve the withstand voltage to suppress electrostatic breakdown of the transistor 150 and the capacitive element 160.

<Source electrode and drain electrode>
As a material that can be used for the source electrode 112a and the drain electrode 112b,
A single metal composed of aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, or tungsten, or an alloy containing the same as a main component can be used as a single layer structure or a laminated structure. For example, 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 tungsten film, a two-layer structure in which a copper film is laminated on a molybdenum film, and an alloy film containing molybdenum and tungsten. Two-layer structure in which a copper film is laminated, a two-layer structure in which a copper film is laminated on a copper-magnesium-aluminum alloy film,
A three-layer structure, molybdenum film or molybdenum nitride, in which a titanium film or titanium nitride film is overlaid on the titanium film or titanium nitride film, and an aluminum film or copper film is laminated, and a titanium film or titanium nitride film is formed on the titanium film or titanium nitride film. There is a three-layer structure in which a film and an aluminum film or a copper film are laminated on the molybdenum film or the molybdenum nitride film, and a molybdenum film or a molybdenum nitride film is formed on the film. When the source electrode 112a and the drain electrode 112b have a three-layer structure, the first and third layers include titanium, titanium nitride, molybdenum, tungsten, an alloy containing molybdenum and tungsten, and an alloy containing molybdenum and zirconium. Alternatively, it is preferable to form a film made of molybdenum nitride and to form a film made of a low resistance material such as copper, aluminum, gold or silver, or an alloy of copper and manganese in the second layer.
A transparent conductive material containing indium oxide, tin oxide or zinc oxide may be used. Further, the materials that can be used for the source electrode 112a and the drain electrode 112b can be formed, for example, by using a sputtering method.

<Protective insulating film>
The insulating films 114, 116, 118 that function as the protective insulating film of the transistor 150 and the insulating film 118 that functions as the protective insulating film of the capacitive element 160 include a silicon oxide film and a silicon oxide nitride film by a plasma CVD method, a sputtering method, or the like. , Silicon nitride oxide film,
An insulating layer containing one or more of silicon nitride film, aluminum oxide film, hafnium oxide film, yttrium oxide film, zirconium oxide film, gallium oxide film, tantalum oxide film, magnesium oxide film, lanthanum oxide film, cerium oxide film and neodymium oxide film. , Can be used respectively.

In the capacitive element 160, the insulating film 118 also has a function of lowering the resistivity of the first oxide semiconductor film 110b that functions as an electrode of the capacitive element 160.

Further, the first oxide semiconductor film 110 that functions as a channel region of the transistor 150
The insulating film 114 in contact with a is preferably an oxide insulating film, and an insulating film capable of releasing oxygen is used. In other words, the insulating film capable of releasing oxygen is an insulating film having a region containing oxygen in excess of the stoichiometric composition (oxygen excess region). In order to provide the oxygen excess region in the insulating film 114, for example, the insulating film 114 may be formed in an oxygen atmosphere. Alternatively, oxygen may be introduced into the insulating film 114 after the film formation to form an oxygen excess region. As a method for introducing oxygen, an ion implantation method, an ion doping method, a plasma implantation ion implantation method, a plasma treatment, or the like can be used.

By using an insulating film capable of releasing oxygen as the insulating film 114, oxygen is transferred to the first oxide semiconductor film 110a functioning as a channel region of the transistor 150, and the first oxide semiconductor film 110a is transferred. It is possible to reduce the amount of oxygen deficiency. For example, an oxygen molecule measured by a heated desorption gas analysis (hereinafter referred to as TDS analysis) performed by a heat treatment in which the surface temperature of the film is 100 ° C. or higher and 700 ° C. or lower, preferably 100 ° C. or higher and 500 ° C. or lower. By using an insulating film having an emission amount of 1.0 × 10 ¹⁸ molecules / cm ³ or more, the amount of oxygen deficiency contained in the first oxide semiconductor film 110a can be reduced.

The thickness of the insulating film 114 is 5 nm or more and 150 nm or less, preferably 5 nm or more and 50.
It can be nm or less, preferably 10 nm or more and 30 nm or less. The thickness of the insulating film 116 can be 30 nm or more and 500 nm or less, preferably 150 nm or more and 400 nm or less.

Further, since the insulating films 114 and 116 can use insulating films of the same material, the interface between the insulating film 114 and the insulating film 116 may not be clearly confirmed. Therefore, in the present embodiment, the interface between the insulating film 114 and the insulating film 116 is shown by a broken line. In the present embodiment, the two-layer structure of the insulating film 114 and the insulating film 116 has been described, but the present invention is not limited to this, and for example, the single-layer structure of the insulating film 114, the single-layer structure of the insulating film 116, or 3
It may be a laminated structure having more than one layer.

The source electrode 112a, the drain electrode 112b, and the first oxide semiconductor film 110
An insulating film 122 may be provided between the a and the insulating film 122. Examples of such cases are shown in FIGS. 17A and 17B. The source electrode 112a and the drain electrode 112b and the first oxide semiconductor film 110a are connected to each other via a contact hole provided in the insulating film 122. Insulating film 122
Can adopt the same material and film quality as those described in the insulating film 108.

<How to make a display device>
Next, with respect to an example of the manufacturing method of the semiconductor device shown in FIGS. 1 (A) and 1 (B), FIGS. 2 and 3
Will be described using.

First, a gate electrode including the second oxide semiconductor film 104a and a second oxide semiconductor film 104b functioning as one of the pair of electrodes are formed on the substrate 102. After that, the substrate 1
An insulating film 108 including the insulating films 106 and 107 is formed on the 02 and the second oxide semiconductor films 104a and 104b (see FIG. 2A).

The substrate 102, the second oxide semiconductor films 104a and 104b, and the insulating films 106 and 1
07 can be formed by selecting from the materials listed above. In this embodiment, a glass substrate is used as the substrate 102, and the second oxide semiconductor film 104a is used.
, 104b uses an In—Ga—Zn oxide film (using a metal oxide target of In: Ga: Zn = 1: 1: 1), and the insulating film 106 can release hydrogen. As the insulating film 107, a silicon oxide film capable of releasing oxygen is used.

By providing the second oxide semiconductor films 104a and 104b in contact with a silicon nitride film capable of releasing hydrogen, the resistivity of the second oxide semiconductor films 104a and 104b can be lowered.

Further, the second oxide semiconductor films 104a and 104b are patterned so that a desired region of the oxide semiconductor film remains after forming the oxide semiconductor film on the substrate 102, and then etching unnecessary regions. It is formed by.

Next, the first oxide semiconductor film 110a and the second oxide semiconductor film 104b on the insulating film 108 are placed at positions overlapping with the gate electrode including the second oxide semiconductor film 104a on the insulating film 108.
The first oxide semiconductor film 110b and the first oxide semiconductor film 110b are formed at the positions where they overlap with each other (see FIG. 2B).

The first oxide semiconductor films 110a and 110b can be formed by selecting from the materials listed above. In the present embodiment, the first oxide semiconductor film 110a
, 110b uses an In—Ga—Zn oxide film (using a metal oxide target of In: Ga: Zn = 1: 1: 1).

Further, the first oxide semiconductor films 110a and 110b are patterned so that a desired region of the oxide semiconductor film remains after forming an oxide semiconductor film on the insulating film 108, and then etching unnecessary regions. It is formed by doing.

Further, since the first oxide semiconductor film 110a and the first oxide semiconductor film 110b are formed by processing from the same oxide semiconductor film, they have at least the same metal element. also,
During the etching process of the first oxide semiconductor films 110a and 110b, a part of the insulating film 107 (the region exposed from the first oxide semiconductor films 110a and 110b) is etched by overetching to reduce the film thickness. Sometimes.

It is preferable to perform heat treatment after forming the first oxide semiconductor films 110a and 110b. The heat treatment is performed at a temperature of 250 ° C. or higher and 650 ° C. or lower, preferably 300 ° C. or higher and 500 ° C. or lower, more preferably 350 ° C. or higher and 450 ° C. or lower, and has an inert gas atmosphere, an atmosphere containing 10 ppm or more of oxidizing gas, or a reduced pressure atmosphere. You can do it with. Further, the heat treatment atmosphere may be an atmosphere containing 10 ppm or more of an oxidizing gas in order to supplement the oxygen desorbed from the first oxide semiconductor films 110a and 110b after the heat treatment is performed in the inert gas atmosphere. .. By the heat treatment here, impurities such as hydrogen and water can be removed from at least one of the insulating films 106 and 107 and the first oxide semiconductor films 110a and 110b. The heat treatment may be performed before the first oxide semiconductor films 110a and 110b are processed into an island shape.

In order to impart stable electrical characteristics to the transistor 150 having the first oxide semiconductor film 110a as a channel region, impurities in the first oxide semiconductor film 110a are reduced.
It is effective to make the first oxide semiconductor film 110a true or substantially true.

Next, a conductive film is formed on the insulating film 108 and the first oxide semiconductor films 110a and 110b, patterned so that a desired region of the conductive film remains, and then an unnecessary region is etched. , The source electrode 112a on the insulating film 108 and the first oxide semiconductor film 110a,
And the drain electrode 112b is formed (see FIG. 2C).

The source electrode 112a and the drain electrode 112b can be formed by selecting from the materials listed above. In the present embodiment, the source electrode 112a and the drain electrode 112b use a three-layer laminated structure of a titanium film, an aluminum film, and a titanium film.

Next, the insulating film 108, the first oxide semiconductor films 110a and 110b, and the source electrode 112a
, And the insulating films 114 and 116 are formed on the drain electrode 112b (see FIG. 2D).

The insulating films 114 and 116 can be formed by selecting from the materials listed above. In the present embodiment, silicon oxide films capable of releasing oxygen are used as the insulating films 114 and 116.

Next, the insulating films 114 and 116 are patterned so that the desired regions remain, and then the unnecessary regions are etched to form the opening 140 (see FIG. 3A).

The opening 140 is formed so that the first oxide semiconductor film 110b is exposed. As a method for forming the opening 140, for example, a dry etching method can be used. However, the method for forming the opening 140 is not limited to this, and a wet etching method or a forming method in which a dry etching method and a wet etching method are combined may be used. note that,
The film thickness of the first oxide semiconductor film 110b may be reduced by the etching step for forming the opening 140.

After this, it is preferable to perform heat treatment. By the heat treatment, a part of oxygen contained in the insulating film 114 or the insulating film 116 can be transferred to the first oxide semiconductor film 110a to compensate for the oxygen deficiency in the first oxide semiconductor film 110a. Is. As a result, the amount of oxygen deficiency contained in the first oxide semiconductor film 110a can be reduced. On the other hand, since the amount of oxygen deficiency of the first oxide semiconductor film 110b that does not come into contact with the insulating film 114 is not reduced, the first oxide semiconductor film 110b contains more oxygen deficiency than the first oxide semiconductor film 110a. Will be done. The conditions for the heat treatment can be the same as the heat treatment after the first oxide semiconductor films 110a and 110b are formed.

Next, the insulating film 118 is formed on the insulating film 116 and the first oxide semiconductor film 110b so as to cover the opening 140 (see FIG. 3B).

The insulating film 118 can be formed by selecting from the materials listed above. In the present embodiment, a silicon nitride film capable of releasing hydrogen is used as the insulating film 118. When hydrogen contained in the insulating film 118 diffuses into the first oxide semiconductor film 110b, the resistivity of the first oxide semiconductor film 110b decreases. As the resistivity of the first oxide semiconductor film 110b decreases, the hatching of the first oxide semiconductor film 110b shown in FIGS. 3 (A) and 3 (B) is changed and shown.

The resistivity of the first oxide semiconductor film 110b is at least the resistance of the first oxide semiconductor film 110a.
It is lower than, preferably 1 × 10 ^-3 Ωcm or more and less than 1 × 10 ⁴ Ωcm, and more preferably 1 × 10 ^-3 Ωcm or more and less than 1 × 10 ^-1 Ωcm. The insulating film 11
Reference numeral 8 also has an effect of preventing external impurities such as water, alkali metal, alkaline earth metal and the like from diffusing into the first oxide semiconductor film 110a contained in the transistor 150.

Further, the silicon nitride film used as the insulating film 118 of the present embodiment is preferably formed at a high temperature in order to improve the blocking property, for example, 100 ° C. or higher and below the strain point of the substrate, more preferably 300 ° C. It is preferable to heat the film at a temperature of 400 ° C. or lower to form a film.

Further, with the formation of the first oxide semiconductor film 110b, the capacitive element 160 is manufactured. The capacitive element 160 has a structure in which a dielectric layer is sandwiched between a pair of electrodes, one of the pair of electrodes is the second oxide semiconductor film 104b, and the other of the pair of electrodes is the first oxide semiconductor. Membrane 110
b. Further, the insulating film 108 functions as a dielectric layer of the capacitive element 160.

By the above steps, the transistor 150 and the capacitive element 160 can be formed on the same substrate.

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 2)
In the present embodiment, the semiconductor device of one aspect of the present invention will be described with reference to FIGS. 4 to 6 as a modification of the semiconductor device shown in the first embodiment. The same reference numerals are used for the same reference numerals as those shown in FIGS. 1 to 3 of the first embodiment or the same reference numerals, and the repeated description thereof will be omitted.

<Semiconductor device configuration example (modification example 1)>
4 (A) is a top view of the semiconductor device of one aspect of the present invention, and FIG. 4 (B) is FIG. 4 (A).
) Corresponds to the cross-sectional view of the cut surface between the alternate long and short dash lines EF and between the alternate long and short dash lines GH. In FIG. 4A, a part of the components (gate insulating film, etc.) of the semiconductor device is omitted in order to avoid complication.

The semiconductor device shown in FIGS. 4 (A) and 4 (B) has a transistor 151 including a first oxide semiconductor film 110a and a second oxide semiconductor film 104a, and a capacitance including an insulating film between a pair of electrodes. It has an element 161 and. In the capacitive element 161, one of the pair of electrodes is the first oxide semiconductor film 104b on the same plane as the second oxide semiconductor film 104a, and the other of the pair of electrodes is the conductive film 120.

The transistor 151 includes a gate electrode including a second oxide semiconductor film 104a on the substrate 102, an insulating film 108 functioning as a gate insulating film on the gate electrode including the second oxide semiconductor film 104a, and an insulating film 108. It has a first oxide semiconductor film 110a at a position overlapping with the gate electrode including the second oxide semiconductor film 104a above, and a source electrode 112a and a drain electrode 112b on the first oxide semiconductor film 110a. The transistor 151 shown in FIGS. 4A and 4B has a so-called bottom gate structure.

Further, the insulating films 114, 116, and 118 are formed on the transistor 151, more specifically, on the first oxide semiconductor film 110a, the source electrode 112a, and the drain electrode 112b. The insulating films 114, 116, and 118 have a function as a protective insulating film for the transistor 151. Further, the insulating films 114, 116, and 118 are formed with an opening 142 reaching the drain electrode 112b, and the conductive film 120 is formed on the insulating film 118 so as to cover the opening 142. The conductive film 120 has a function as, for example, a pixel electrode.

The capacitive element 161 has a function as one of the pair of electrodes on the substrate 102.
The second oxide semiconductor film 104b, the insulating films 108, 114, 116, 118 functioning as a dielectric film on the second oxide semiconductor film 104b, and the second insulating film 108, 114, 116, 118. It has a conductive film 120 having a function as the other electrode of a pair of electrodes at positions overlapping with the oxide semiconductor film 104b. That is, the conductive film 120 has a function as a pixel electrode and a function as an electrode of a capacitive element.

As described above, the insulating film 108 functions as a gate insulating film in the transistor 151, and functions as a part of the dielectric film in the capacitive element 161. Further, the insulating films 114, 116 and 118 function as a protective insulating film in the transistor 151.
In the capacitive element 161 it functions as a part of the dielectric film. In addition, FIGS. 4 (A) and 4 (B)
In the above, the configuration in which the insulating films 114, 116, and 118 are provided as a part of the dielectric film has been exemplified, but the present invention is not limited thereto. For example, during the manufacturing process of the transistor 151,
The insulating films 114, 116, 118 of the capacitive element 161 may be removed when the opening 142 is formed.

Further, the capacitive element 161 has translucency. That is, the second capacitance element 161 has.
Oxide semiconductor film 104b, insulating films 108, 114, 116, 118, and conductive film 120
Are each made of a translucent material. In this way, since the capacitive element 161 has translucency, it can be formed large (in a large area) in a region other than the portion where the transistor is formed in the pixel, so that the capacitive value can be increased while increasing the aperture ratio. An increased semiconductor device can be obtained. As a result, a semiconductor device having excellent display quality can be obtained. Further, the capacitive element 161 can be manufactured by using the manufacturing process of the transistor 151. Therefore, it is possible to obtain a semiconductor device having a low manufacturing cost.

As the insulating films 106 and 118, at least an insulating film containing hydrogen is used. also,
As the insulating films 107, 114, and 116, an insulating film containing at least oxygen is used. In this way, the insulating film or transistor 151 used for the transistor 151 and the capacitive element 161
The resistance of the first oxide semiconductor film and the second oxide semiconductor film of the transistor 151 and the capacitive element 161 is controlled by using the insulating film in contact with the capacitive element 161 as the insulating film having the above-described configuration. be able to.

The first oxide semiconductor film 110a and the second oxide semiconductor films 104a and 104b
The resistivity of the above can be controlled by referring to the description of the first embodiment.

The main difference between the semiconductor device shown in FIGS. 1 (A) and 1 (B) of the first embodiment and the semiconductor device shown in FIGS. 4 (A) and 4 (B) is that the other electrode of the capacitive element 161 is conductive. It is a point that the film 120 is used. As described above, the other of the pair of electrodes of the capacitive element 161 may be a conductive film 120 that functions as a pixel electrode.

As described above, in the semiconductor device of one aspect of the present invention, the conductive film that functions as the gate electrode of the transistor and the conductive film that functions as the electrode of the capacitive element are simultaneously formed, in other words, the conductive film functions as the gate electrode of the transistor. By forming the conductive film to be formed and the conductive film functioning as electrodes of the capacitive element on the same surface, it is possible to reduce the manufacturing cost. also,
The conductive film that functions as the gate electrode of the transistor and the conductive film that functions as the electrode of the capacitive element are configured to include an oxide semiconductor film. By appropriately treating the oxide semiconductor film,
It can be a conductive film having high conductivity and translucency. By using the conductive film, translucency can be imparted to the transistor and / or the capacitive element.

The source electrode 112a, the drain electrode 112b, and the first oxide semiconductor film 110
An insulating film 122 may be provided between the a and the insulating film 122. Examples of such cases are shown in FIGS. 18A and 18B.

The conductive film 1 was formed at the same time as the conductive film 120, and was etched at the same time to form the conductive film 1 at the same time.
20a may be provided so as to overlap the channel region of the transistor. Examples of this case are shown in FIGS. 15 (A) and 19 (A). As an example, the conductive film 120a has the same material because the film is formed at the same time as the conductive film 120, etched at the same time, and formed at the same time. Therefore, it is possible to suppress an increase in process steps. However, one aspect of the embodiment of the present invention is not limited to this. The conductive film 120a may be formed by a process different from that of the conductive film 120. The conductive film 120a has a region that overlaps with the channel region of the transistor. Therefore, the conductive film 120a has a function as a second gate electrode of the transistor. Therefore, the conductive film 120a may be connected to the second oxide semiconductor film 104a. Alternatively, the conductive film 120a may not be connected to the second oxide semiconductor film 104a and may be supplied with a signal different from that of the second oxide semiconductor film 104a or a different potential.

Here, details of other components of the semiconductor device shown in FIGS. 4A and 4B will be described below.

<Conductor>
The conductive film 120 has a function as a pixel electrode. As the conductive film 120, for example, a material having translucency in visible light may be used. Specifically, indium (In),
It is preferable to use a material containing one selected from zinc (Zn) and tin (Sn). The conductive film 120 includes, for example, an indium oxide containing tungsten oxide, an indium zinc oxide containing tungsten oxide, an indium oxide containing titanium oxide, an indium tin oxide containing titanium oxide, and an indium tin oxide (ITO). ), Indium zinc oxide, indium tin oxide to which silicon oxide is added, and other translucent conductive materials can be used. Further, the conductive film 120 can be formed by using, for example, a sputtering method.

<Method of manufacturing a display device (modification example 1)>
Next, with respect to an example of the manufacturing method of the semiconductor device shown in FIGS. 4A and 4B, FIGS. 5 and 6 are shown.
Will be described using.

First, a gate electrode including the second oxide semiconductor film 104a and a second oxide semiconductor film 104b functioning as one of the pair of electrodes are formed on the substrate 102. Then, the insulating film 108 including the insulating films 106 and 107 is formed on the second oxide semiconductor films 104a and 104b (see FIG. 5A).

Next, the first oxide semiconductor film 110a is formed on the insulating film 108 at a position superimposing on the gate electrode including the second oxide semiconductor film 104a (see FIG. 5B).

The first oxide semiconductor film 110a is formed by forming an oxide semiconductor film on the insulating film 108, patterning the oxide semiconductor film so that a desired region remains, and then etching an unnecessary region. Will be done.

Further, during the etching process of the first oxide semiconductor film 110a, a part of the insulating film 107 (the region exposed from the first oxide semiconductor film 110a) may be etched by overetching to reduce the film thickness. be.

It is preferable to perform heat treatment after forming the first oxide semiconductor film 110a. The heat treatment can be performed by taking into consideration the heat treatment after the formation of the first oxide semiconductor film 110a of the first embodiment.

Next, a conductive film is formed on the insulating film 108 and the first oxide semiconductor film 110a, patterned so that a desired region of the conductive film remains, and then an unnecessary region is etched. A source electrode 112a and a drain electrode 112b are formed on the oxide semiconductor film 110a of the above (see FIG. 5C).

Next, the insulating films 114, 116, and 118 are formed on the insulating film 108, the first oxide semiconductor film 110a, the source electrode 112a, and the drain electrode 112b (see FIG. 5D).

Next, the insulating films 114, 116, and 118 are patterned so that the desired regions remain, and then the unnecessary regions are etched to form the opening 142 (see FIG. 6A).

The opening 142 is formed so that the drain electrode 112b is exposed. As a method for forming the opening 142, for example, a dry etching method can be used. However, opening 1
The forming method of 42 is not limited to this, and may be a wet etching method or a forming method in which a dry etching method and a wet etching method are combined.

Next, a conductive film is formed on the insulating film 118 so as to cover the opening 142, and patterning and etching are performed so that a desired region of the conductive film remains to form the conductive film 120 (FIG. 6 (B).
)reference).

By the above steps, the transistor 151 and the capacitive element 161 can be formed on the same substrate.

The insulating film 118a may be arranged on the insulating film 118. An example in that case is shown in FIG.
(B), (C), and FIGS. 19 (B), 19 (C). As the insulating film 118a, for example,
It can be formed using an organic resin material. Examples of the material applicable to the insulating film 118a include an acrylic resin, a polyimide resin, and a polyamide resin.

As shown in FIGS. 15 (C) and 19 (C), the conductive film 121 may be provided. The conductive film 121 may be provided so as to overlap the channel region of the transistor. The conductive film 121 may be formed by using the same material as that described in the conductive film 120. The conductive film 121 has a region that overlaps with the channel region of the transistor. Therefore, the conductive film 121 has a function as a second gate electrode of the transistor. Therefore, the conductive film 121 is
It may be connected to the second oxide semiconductor film 104a. Alternatively, the conductive film 121 is a second
A signal different from that of the second oxide semiconductor film 104a or a different potential may be supplied without being connected to the oxide semiconductor film 104a of the second oxide semiconductor film 104a.

The conductive film 1 was formed at the same time as the conductive film 121, and was etched at the same time to form the conductive film 1 at the same time.
The capacitive element may be configured by providing 21a so as to overlap the electrodes of the capacitive element. Examples of such cases are shown in FIGS. 20 (A), (B), and (C). As a result, the capacitance value of the capacitive element can be increased.

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 3)
In the present embodiment, the semiconductor device of one aspect of the present invention will be described with reference to FIG. 7 as a modification of the semiconductor device shown in the first embodiment. The same reference numerals are used for the same reference numerals as those shown in FIGS. 1 to 3 of the first embodiment or the same reference numerals, and the repeated description thereof will be omitted.

<Semiconductor device configuration example (modification example 2)>
7 (A) is a top view of the semiconductor device of one aspect of the present invention, and FIG. 7 (B) is FIG. 7 (A).
) Corresponds to the cross-sectional view of the cut surface between the alternate long and short dash lines IJ and between the alternate long and short dash lines KL. In FIG. 7A, a part of the components (gate insulating film, etc.) of the semiconductor device is omitted in order to avoid complication.

The semiconductor device shown in FIGS. 7A and 7B has a transistor 152 including a first oxide semiconductor film 110a and a second oxide semiconductor film 104a, and a capacitance including an insulating film between a pair of electrodes. It has an element 162 and.

The transistor 152 includes a gate electrode including a second oxide semiconductor film 104a on the substrate 102, an insulating film 108 functioning as a gate insulating film on the gate electrode including the second oxide semiconductor film 104a, and an insulating film 108. It has a first oxide semiconductor film 110a at a position overlapping with the gate electrode including the second oxide semiconductor film 104a above, and a source electrode 112a and a drain electrode 112b on the first oxide semiconductor film 110a. The transistor 152 shown in FIGS. 7A and 7B has a so-called bottom gate structure.

Further, the insulating films 114, 116, and 118 are formed on the transistor 152, more specifically, on the first oxide semiconductor film 110a, the source electrode 112a, and the drain electrode 112b. The insulating films 114, 116, and 118 have a function as a protective insulating film for the transistor 152. Further, the insulating films 114, 116, and 118 are formed with an opening 142 reaching the drain electrode 112b, and the conductive film 120 is formed on the insulating film 118 so as to cover the opening 142. The conductive film 120 has a function as, for example, a pixel electrode.

Further, in the capacitive element 162, one of the pair of electrodes is the second oxide semiconductor film 104b, and the other of the pair of electrodes is the conductive film 120. Further, the capacitive element 162 further has an electrode between the pair of electrodes. The electrode is a first oxide semiconductor film 110b formed on the same plane as the first oxide semiconductor film 110a.

As described above, by further providing the electrodes between the pair of electrodes, the capacitance can be increased without increasing the area of the capacitive element. The capacitive element 162 can be seen as having the following structure, for example. The capacitive element 162 includes a first capacitive element having an insulating film 108 sandwiched between the second oxide semiconductor film 104b and the first oxide semiconductor film 110a as a dielectric film.
The structure is such that a second capacitive element having an insulating film 118 sandwiched between the first oxide semiconductor film 110a and the conductive film 120 as a dielectric film is laminated.

As described above, the insulating film 108 functions as a gate insulating film in the transistor 152, and functions as a part of the dielectric film in the capacitive element 162. In addition, the insulating film 11
4, 116, 118 function as a protective insulating film in the transistor 152. Further, the insulating film 118 functions as a part of the dielectric film in the capacitive element 162.

Further, the capacitive element 162 has translucency. That is, the first capacitance element 162 has.
The oxide semiconductor film 110b, the second oxide semiconductor film 104b, the insulating films 108 and 118, and the conductive film 120 are each made of a translucent material. In this way, since the capacitive element 162 has translucency, it can be formed large (in a large area) in a region other than the portion where the transistor is formed in the pixel, so that the capacitive value can be increased while increasing the aperture ratio. An increased semiconductor device can be obtained. As a result, a semiconductor device having excellent display quality can be obtained. Further, the capacitive element 162 can be manufactured by using the manufacturing process of the transistor 152. Therefore, it is possible to obtain a semiconductor device having a low manufacturing cost.

As the insulating films 106 and 118, at least an insulating film containing hydrogen is used. also,
As the insulating films 107, 114, and 116, an insulating film containing at least oxygen is used. In this way, the insulating film or transistor 152 used for the transistor 152 and the capacitive element 162
The resistance of the first oxide semiconductor film and the second oxide semiconductor film of the transistor 152 and the capacitive element 162 is controlled by using the insulating film in contact with the capacitive element 162 as the insulating film having the above-described configuration. be able to.

The first oxide semiconductor films 110a and 110b and the second oxide semiconductor films 104a,
The resistivity of 104b can be controlled by referring to the description of the first embodiment.

The main difference between the semiconductor device shown in FIGS. 1 (A) and 1 (B) of the first embodiment and the semiconductor device shown in FIGS. 7 (A) and 7 (B) is the electrode structure of the capacitive element 162.

In the semiconductor device of one aspect of the present invention, a conductive film that functions as a gate electrode of a transistor and a conductive film that functions as an electrode of a capacitive element are simultaneously formed, in other words, a conductive film that functions as a gate electrode of a transistor. By forming a conductive film that functions as an electrode of a capacitive element on the same surface, it is possible to reduce the manufacturing cost. Further, the conductive film that functions as the gate electrode of the transistor and the conductive film that functions as the electrode of the capacitive element are configured to include an oxide semiconductor film. By appropriately treating the oxide semiconductor film, it is possible to obtain a conductive film having high conductivity and translucency. By using the conductive film, translucency can be imparted to the transistor and / or the capacitive element.

As a method for manufacturing the semiconductor device shown in FIGS. 7A and 7B, FIGS. 1A and 1B are used.
It can be formed by combining the semiconductor device shown in FIG. 4 and the method for manufacturing the semiconductor device shown in FIGS. 4A and 4B.

As in FIG. 15A, the conductive film 120a may be provided so as to overlap the channel region of the transistor. An example of such a case is shown in FIGS. 16 (A) and 19 (A).

Further, the insulating film 118a may be arranged on the insulating film 118 as in FIGS. 15B and 15C. Examples of such cases are shown in FIGS. 16 (B) and 16 (C), and FIGS. 19 (B) and 19 (C).

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 4)
In the present embodiment, the semiconductor device of one aspect of the present invention will be described with reference to FIGS. 8 to 10 as a modification of the semiconductor device shown in the first embodiment. The same reference numerals are used for the same reference numerals as those shown in FIGS. 1 to 3 of the first embodiment or the same reference numerals, and the repeated description thereof will be omitted.

<Semiconductor device configuration example (modification example 3)>
8 (A) is a top view of the semiconductor device of one aspect of the present invention, and FIG. 8 (B) is FIG. 8 (A).
) Corresponds to the cross-sectional view of the cut surface between the alternate long and short dash line MN and between the alternate long and short dash line OP. In FIG. 8A, a part of the components (gate insulating film, etc.) of the semiconductor device is omitted in order to avoid complication.

The semiconductor device shown in FIGS. 8A and 8B has a transistor 250 including a first oxide semiconductor film 210 and a second oxide semiconductor film 204a, and a capacitance including an insulating film between a pair of electrodes. It has an element 260 and. In the capacitive element 260, one of the pair of electrodes is the second oxide semiconductor film 204b on the same plane as the second oxide semiconductor film 204a, and the other of the pair of electrodes is the conductive film 220.

The transistor 250 includes an insulating film 216 on the substrate 202, a first oxide semiconductor film 210 on the insulating film 216, a source electrode 212a and a drain electrode 212b on the first oxide semiconductor film 210, and a first one. Insulating film 2 that functions as a gate insulating film on the oxide semiconductor film 210
It has 08 and a gate electrode including a second oxide semiconductor film 204a at a position overlapping with the first oxide semiconductor film 210 on the insulating film 208. The transistor 250 shown in FIGS. 8A and 8B has a so-called top gate structure.

Further, the insulating films 218 and 217 are formed on the transistor 250, more specifically, on the gate electrode including the second oxide semiconductor film 204a, the source electrode 212a, and the drain electrode 212b. The insulating films 218 and 217 have a function as a protective insulating film for the transistor 250. Further, the insulating film 218 and 217 have an opening 240 reaching the drain electrode 212b.
Is formed, and the conductive film 220 is formed on the insulating film 217 so as to cover the opening 240. The conductive film 220 has a function as, for example, a pixel electrode.

The capacitive element 260 is a second oxide semiconductor film 204 having a function as one of an insulating film 216 on the substrate 202, an insulating film 208 on the insulating film 216, and a pair of electrodes on the insulating film 208.
b and the insulating film 218, 217 that functions as a dielectric film on the second oxide semiconductor film 204b.
And a conductive film 220 having a function as the other of a pair of electrodes at positions overlapping with the second oxide semiconductor film 204b via the insulating film 218 and 217. That is, the conductive film 220
Has a function as a pixel electrode and a function as an electrode of a capacitive element.

As described above, the insulating film 208 functions as a gate insulating film in the transistor 250, and functions as a part of the dielectric film in the capacitive element 260. Further, the insulating films 218 and 217 function as a protective insulating film in the transistor 250, and function as a part of the dielectric film in the capacitive element 260. In addition, in FIGS. 8A and 8B, the configuration in which the insulating film 218 and 217 are provided as a part of the dielectric film is illustrated, but the present invention is not limited thereto. For example, in the manufacturing process of the transistor 250, a part of the insulating films 218 and 217 of the capacitive element 260 may be removed.

Further, the capacitive element 260 has translucency. That is, the insulating films 216, 206, 207, 218, and 217 of the capacitive element 260 are each made of a translucent material. In this way, since the capacitive element 260 has translucency, it can be formed large (in a large area) in a region other than the portion where the transistor is formed in the pixel, so that the capacitive value can be increased while increasing the aperture ratio. An increased semiconductor device can be obtained. As a result, a semiconductor device having excellent display quality can be obtained. Further, the capacitive element 260 can be manufactured by using the manufacturing process of the transistor 250. Therefore, it is possible to obtain a semiconductor device having a low manufacturing cost.

As the insulating films 207 and 218, an insulating film containing at least hydrogen is used. also,
As the insulating films 216, 206 and 217, an insulating film containing at least oxygen is used. In this way, the insulating film or transistor 250 used for the transistor 250 and the capacitive element 260
The resistance of the first oxide semiconductor film and the second oxide semiconductor film of the transistor 250 and the capacitive element 260 is controlled by using the insulating film in contact with the capacitive element 260 as the insulating film having the above-described configuration. be able to.

Specifically, in the transistor 250, since the first oxide semiconductor film 210 is used as a channel forming region, the resistivity is higher than that of the second oxide semiconductor films 204a and 204b. On the other hand, since the second oxide semiconductor films 204a and 204b have a function as electrodes, the resistivity is low.

Here, the first oxide semiconductor film 210 and the second oxide semiconductor films 204a and 204b
The method of controlling the resistivity of the above will be described below.

<Control method 2 of resistivity of oxide semiconductor>
The oxide semiconductor that can be used for the first oxide semiconductor film 210 and the second oxide semiconductor films 204a and 204b depends on the oxygen deficiency in the film and / or the concentration of impurities such as hydrogen and water in the film. It is a semiconductor material whose resistance can be controlled. Therefore, a treatment for increasing the oxygen deficiency and / or the impurity concentration in the first oxide semiconductor film 210 and the second oxide semiconductor films 204a and 204b, or a treatment for reducing the oxygen deficiency and / or the impurity concentration is selected. Thereby, the resistance of each oxide semiconductor can be controlled.

Specifically, the second oxide semiconductor film 2 that functions as the gate electrode of the transistor 250.
04a, the oxide semiconductor film used for the second oxide semiconductor film 204b functioning as the electrode of the capacitive element 260 is subjected to plasma treatment to increase oxygen deficiency in the oxide semiconductor film, and / or the oxide semiconductor. By increasing impurities such as hydrogen and water in the film, it is possible to obtain an oxide semiconductor having a high carrier density and low resistance. Further, an oxide semiconductor having a high carrier density and a low resistance is obtained by forming an oxide semiconductor in contact with an insulating film containing hydrogen and diffusing hydrogen from the insulating film containing hydrogen to the oxide semiconductor. Can be done.

On the other hand, the first oxide semiconductor film 2 that functions as a channel forming region of the transistor 250.
10 is configured to be in contact with the insulating film 218 containing hydrogen by providing the insulating films 216 and 206. Further, at least one of the insulating films 216 and 206 is an insulating film capable of releasing oxygen, so that oxygen can be supplied to the first oxide semiconductor film 210. The first oxide semiconductor film 210 to which oxygen is supplied becomes a high-resistance oxide semiconductor by compensating for oxygen deficiency in the film or at the interface. As the insulating film capable of releasing oxygen, for example, a silicon oxide film or a silicon nitride film can be used.

As described above, in the semiconductor device of one aspect of the present invention, the conductive film that functions as the gate electrode of the transistor and the conductive film that functions as the electrode of the capacitive element are simultaneously formed, in other words, the conductive film functions as the gate electrode of the transistor. By forming the conductive film to be formed and the conductive film functioning as electrodes of the capacitive element on the same surface, it is possible to reduce the manufacturing cost. also,
The conductive film that functions as the gate electrode of the transistor and the conductive film that functions as the electrode of the capacitive element are configured to include an oxide semiconductor film. By appropriately treating the oxide semiconductor film,
It can be a conductive film having high conductivity and translucency. By using the conductive film, translucency can be imparted to the transistor and / or the capacitive element.

Here, details of other components of the semiconductor device shown in FIGS. 8A and 8B will be described below.

<Insulating film>
The insulating film 216 can be formed by using the materials listed in the insulating film 116 of the first embodiment. Further, the insulating films 206 and 207 can be formed by using the materials listed in the insulating films 106 and 107 of the first embodiment, respectively.

<First oxide semiconductor film and second oxide semiconductor film>
The first oxide semiconductor film 210 is the first oxide semiconductor film 110a of the first embodiment.
It can be formed by using the materials listed in. Further, the second oxide semiconductor film 2
The 04a and 204b can be formed by using the materials listed in the second oxide semiconductor films 104a and 104b of the first embodiment.

<Source electrode and drain electrode>
The source electrode 212a and the drain electrode 212b include the source electrode 1 of the first embodiment.
It can be formed by using the materials listed in 12a and the drain electrode 112b.

<Conductor>
The conductive film 220 can be formed by using the materials listed in the conductive film 120 of the second embodiment.

<Method of manufacturing a display device (modification example 2)>
Next, with respect to an example of the manufacturing method of the semiconductor device shown in FIGS. 8A and 8B, FIGS. 9 and 1
It will be described using 0.

First, the insulating film 216 is formed on the substrate 202, and the oxide semiconductor film is formed on the insulating film 216. Then, the oxide semiconductor film is patterned so that a desired region remains, and then an unnecessary region is etched to form the first oxide semiconductor film 210 (see FIG. 9A).

Next, a conductive film is formed on the insulating film 216 and the first oxide semiconductor film 210, patterned so that a desired region of the conductive film remains, and then an unnecessary region is etched to obtain a source electrode. The 212a and the drain electrode 212b are formed (see FIG. 9B).

Next, an insulating film 208 including the insulating films 206 and 207 and a second oxide semiconductor film 204 are formed on the insulating film 216, the first oxide semiconductor film 210, the source electrode 212a, and the drain electrode 212b. (See FIG. 9 (C)).

Next, a resist mask is formed on the second oxide semiconductor film 204, patterned so that a desired region of the second oxide semiconductor film 204 remains, and then an unnecessary region is etched to obtain a second. The oxide semiconductor films 204a and 204b of the above are formed. At this time, the insulating films 206 and 207 below the second oxide semiconductor films 204a and 204b are also etched at the same time to form the insulating films 206 and 207 separated in an island shape (see FIG. 9D).

Next, the insulating films 218 and 217 are formed on the insulating film 216, the source electrode 212a, the drain electrode 212b, and the second oxide semiconductor films 204a and 204b (see FIG. 10A).
..

Next, a resist mask is formed on the insulating film 217, the insulating film 218 and 217 are patterned so that the desired region remains, and then the unnecessary region is etched to form the opening 240. The opening 240 is formed so as to reach the drain electrode 212b (
See FIG. 10 (B)).

Next, a conductive film is formed on the insulating film 217 so as to cover the opening 240, a resist mask is formed on the conductive film, patterning is performed so that a desired region of the conductive film remains, and then unnecessary regions are formed. The conductive film 220 is formed by etching (see FIG. 10C).

By the above steps, the transistor 250 and the capacitive element 260 can be formed on the same substrate.

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 semiconductor device of one aspect of the present invention will be described with reference to FIG. 11 as a modification of the semiconductor device shown in the first embodiment.

<Semiconductor device configuration example (modification example 4)>
In the semiconductor device shown in FIG. 11A, the first oxide semiconductor films 110a and 110b of the transistor 150 and the capacitive element 160 shown in the first embodiment are provided with the oxide laminated films 410a and 410.
It is a configuration of b. Therefore, other configurations include the transistor 150 and the capacitive element 1.
It is the same as 60, and the detailed description thereof will be omitted.

Details of the oxide laminated films 410a and 410b will be described below.

The oxide laminated film 410a and 410b have an oxide semiconductor film 420a and 420b and an oxide film 422a and 422b. In the following description, the oxide semiconductor film 420
The a and 420b will be referred to as an oxide semiconductor film 420, and the oxide films 422a and 422b will be referred to as an oxide film 422, respectively.

As the oxide semiconductor film 420 and the oxide film 422, it is preferable to use a metal oxide having at least one of the same constituent elements. Alternatively, the oxide semiconductor film 420 and the oxide film 42
The constituent elements of 2 may be the same, and the compositions of the two may be different.

The oxide semiconductor film 420 is an In—M—Zn oxide (M is Al, Ti, Ga, Y, Zr, L).
In the case of a, Ce, Nd, Sn or Hf), the atomic number ratio of the metal element of the sputtering target used for forming the In—M—Zn oxide shall satisfy In ≧ M and Zn ≧ M. Is preferable. As the atomic number ratio of the metal element of such a sputtering target,
In: M: Zn = 1: 1: 1, In: M: Zn = 5: 5: 6 (1: 1: 1.2), In:
M: Zn = 3: 1: 2, etc. are preferable. The atomic number ratio of the oxide semiconductor film 420 to be formed includes a variation of plus or minus 20% of the atomic number ratio of the metal element contained in the sputtering target as an error.

When the oxide semiconductor film 420 is an In—M—Zn oxide and the sum of In and M is 100 atomic%, the atomic number ratio of In and M is preferably 25 at.
Omic% or more, M is less than 75atomic%, more preferably In is 34atomi
It is assumed that c% or more and M is less than 66 atomic%.

The oxide semiconductor film 420 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 an oxide semiconductor having a wide energy gap, the off-current of the transistor can be reduced.

The thickness of the oxide semiconductor film 420 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 50 nm or less.

The oxide film 422 is typically In—Ga oxide, In—Zn oxide, In—M—Z.
It is n oxide (M represents Al, Ti, Ga, Y, Zr, La, Ce, Nd, Sn or Hf), and the energy at the lower end of the conduction band is lower than that of the oxide semiconductor film 420 at the vacuum level. Nearly, typically, the difference between the energy at the lower end of the conduction band of the oxide film 422 and the energy at the lower end of the conduction band of the oxide semiconductor film 420 is 0.05 eV or more, 0.07 eV or more, 0.1 eV.
The above, or 0.15 eV or more, and 2 eV or less, 1 eV or less, 0.5 eV or less, or 0.4 eV or less. That is, the difference between the electron affinity of the oxide film 422 and the electron affinity of the oxide semiconductor film 420 is 0.05 eV or more, 0.07 eV or more, 0.1 eV or more, or 0.
.. It is 15 eV or more and 2 eV or less, 1 eV or less, 0.5 eV or less, or 0.4 eV or less.

When the oxide film 422 has the above element M in an atomic number ratio higher than that of In, it may have the following effects. (1) Increase the energy gap of the oxide film 422. (2)
The electron affinity of the oxide film 422 is reduced. (3) Shield impurities from the outside. (4)
Insulation is higher than that of the oxide semiconductor film 420. Further, since the element M is a metal element having a strong binding force with oxygen, having M at a higher atomic number ratio than In makes it difficult for oxygen deficiency to occur.

When the oxide film 422 is an In—M—Zn oxide, the sum of In and M is 100 ato.
When mic%, the atomic number ratio of In and M is preferably 50 atomic% of In.
Less than, M is 50 atomic% or more, more preferably In is less than 25 atomic%, M is 75 atomic% or more.

Further, the oxide semiconductor film 420 and the oxide film 422 are In—M—Zn oxides (M is Al).
, Ti, Ga, Y, Zr, La, Ce, Nd, Sn or Hf), the number of atoms of M contained in the oxide film 422 is larger than that of the oxide semiconductor film 420, which is representative. The atom number ratio is 1.5 times or more, preferably 2 times or more, and more preferably 3 times or more higher than that of the atoms contained in the oxide semiconductor film 420.

Further, the oxide film 422 is In: M: Zn = x ₁ : y ₁ : z ₁ [atomic number ratio], and the oxide semiconductor film 420 is In: M: Zn = x ₂ : y ₂ : z ₂ [atomic number]. Ratio], y ₁ / x ₁ is y
It is larger than ₂ / x ₂ , preferably y ₁ / x ₁ is 1.5 times or more than y ₂ / x ₂ . More preferably, y ₁ / x ₁ is more than twice as large as y ₂ / x ₂ , and more preferably.
y ₁ / x ₁ is more than 3 times larger than y ₂ / x ₂ . At this time, in the oxide semiconductor film 420, when y ₂ is x ₂ or more, it is preferable because stable electrical characteristics can be imparted to the transistor using the oxide semiconductor. However, when y ₂ becomes 3 times or more of x ₂ , the field effect mobility of the transistor using the oxide semiconductor decreases, so that y ₂ is preferably less than 3 times x ₂ .

When the oxide semiconductor film 420 and the oxide film 422 are In-M-Zn oxides, In-M-
The atomic number ratio of the metal element of the sputtering target used to form the Zn oxide is
It is preferable to satisfy M> In and Zn ≧ M. As the atomic number ratio of the metal element of such a sputtering target, In: Ga: Zn = 1: 3: 2, In: Ga: Zn = 1: 3:
3, In: Ga: Zn = 1: 3: 4, In: Ga: Zn = 1: 3: 5, In: Ga: Zn
= 1: 3: 6, In: Ga: Zn = 1: 3: 7, In: Ga: Zn = 1: 3: 8, In:
Ga: Zn = 1: 3: 9, In: Ga: Zn = 1: 3:10, In: Ga: Zn = 1: 6
: 4, In: Ga: Zn = 1: 6: 5, In: Ga: Zn = 1: 6: 6, In: Ga: Z
n = 1: 6: 7, In: Ga: Zn = 1: 6: 8, In: Ga: Zn = 1: 6: 9, In
: Ga: Zn = 1: 6: 10 is preferable. The atomic number ratios of the metal elements contained in the oxide semiconductor film 420 and the oxide film 422 formed by using the sputtering target are each plus the atomic number ratios of the metal elements contained in the sputtering target as an error. Includes -20% fluctuation.

Not limited to these, a transistor having an appropriate composition may be used according to the required semiconductor characteristics and electrical characteristics (field effect mobility, threshold voltage, etc.) of the transistor. Further, in order to obtain the required semiconductor characteristics of the transistor, the carrier density, impurity concentration, defect density, atomic number ratio between metal element and oxygen, interatomic distance, density, etc. of the oxide semiconductor film 420 shall be appropriate. Is preferable.

The oxide film 422 also functions as a damage mitigating film for the oxide semiconductor film 420 when the insulating film 114 or the insulating film 116 to be formed later is formed. The thickness of the oxide film 422 is 3
It is nm or more and 100 nm or less, preferably 3 nm or more and 50 nm.

When silicon or carbon, which is one of the Group 14 elements, is contained in the oxide semiconductor film 420, oxygen deficiency increases in the oxide semiconductor film 420, resulting in n-type formation. Therefore, the concentration of silicon or carbon in the oxide semiconductor film 420, or the concentration of silicon or carbon near the interface between the oxide film 422 and the oxide semiconductor film 420 (concentration obtained by the secondary ion mass analysis method) is determined. 2, 2 × 10 ¹⁸ atoms / cm ³ or less, preferably 2 × 10 ¹⁷ atoms
/ Cm ³ or less.

Further, in the oxide semiconductor film 420, the concentration of the alkali metal or alkaline earth metal obtained by the secondary ion mass spectrometry is 1 × 10 ¹⁸ atoms / cm ³ or less, preferably 2 × 10 ¹⁶ atoms / cm ³ or less. To. Alkali metals and alkaline earth metals are
When combined with an oxide semiconductor, carriers may be generated, which may increase the off-current of the transistor. Therefore, it is preferable to reduce the concentration of the alkali metal or alkaline earth metal in the oxide semiconductor film 420.

Further, when nitrogen is contained in the oxide semiconductor film 420, electrons as carriers are generated, the carrier density increases, and the n-type is easily formed. As a result, a transistor using an oxide semiconductor containing nitrogen tends to have normally-on characteristics. Therefore, in the oxide semiconductor film 420, it is preferable that nitrogen is reduced as much as possible, for example, the nitrogen concentration obtained by the secondary ion mass spectrometry is preferably 5 × 10 ¹⁸ atoms / cm ³ or less. ..

The oxide semiconductor film 420 and the oxide film 422 are not simply laminated, but have continuous junctions (here, in particular, a structure in which the energy at the lower end of the conduction band continuously changes between the films) is formed. To make. That is, the laminated structure is such that impurities such as trap centers and recombination centers that form defect levels do not exist at the interface of each film. If impurities are mixed between the laminated oxide semiconductor film 420 and the oxide film 422, the continuity of the energy band is lost and carriers are trapped at the interface.
Or it rejoins and disappears.

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

Here, the band structure of the oxide laminated film will be described with reference to FIG. 11B.

FIG. 11B schematically shows a part of the band structure of the oxide laminated film and the insulating film in contact with the oxide laminated film. Here, a case where a silicon oxide film is provided as the insulating film 107 and the insulating film 114 will be described. Note that EcI1 shown in FIG. 11B indicates the energy at the lower end of the conduction band of the silicon oxide film used as the insulating film 107, and EcS1 is the oxide semiconductor film 42.
0 indicates the energy at the lower end of the conduction band, EcS2 indicates the energy at the lower end of the conduction band of the oxide film 422, and EcI2 indicates the energy at the lower end of the conduction band of the silicon oxide film used as the insulating film 114.

As shown in FIG. 11B, in the oxide semiconductor film 420 and the oxide film 422, the energy at the lower end of the conduction band changes gently without a barrier. In other words, it can be said that it changes continuously. This is because the oxide semiconductor film 420 and the oxide film 422 contain a common element, and a mixed layer is formed by mutual movement of oxygen between the oxide semiconductor film 420 and the oxide film 422. It can be said that there is.

From FIG. 11B, it can be seen that the oxide semiconductor film 420 becomes a well, and the channel region is formed on the oxide semiconductor film 420. Since the energy at the lower end of the conduction band of the oxide semiconductor film 420 and the oxide film 422 is continuously changed, the oxide semiconductor film 42
It can be said that 0 and the oxide film 422 are continuously bonded.

As shown in FIG. 11B, in the vicinity of the interface between the oxide film 422 and the insulating film 114, trap levels caused by impurities or defects such as silicon or carbon, which are constituent elements of the insulating film 114, are present. However, by providing the oxide film 422, the oxide semiconductor film 420 and the trap level can be kept away from each other. However, when the energy difference between EcS1 and EcS2 is small, the electrons of the oxide semiconductor film 420 may exceed the energy difference and reach the trap level. When electrons are captured at the trap level, a negative fixed charge is generated at the interface of the insulating film, and the threshold voltage of the transistor shifts in the positive direction.
Therefore, the energy difference between EcS1 and EcS2 is 0.1 eV or more, preferably 0.
When it is 15 eV or more, the fluctuation of the threshold voltage of the transistor is reduced and stable electrical characteristics are obtained, which is preferable.

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 6)
In this embodiment, an example of an oxide semiconductor film applicable to a transistor and a capacitive element of the semiconductor device of one aspect of the present invention will be described.

<Crystallinity of oxide semiconductor film>
Hereinafter, the structure of the oxide semiconductor film will be described.

Oxide semiconductor films are roughly classified into non-single crystal oxide semiconductor films and single crystal oxide semiconductor films.
The non-single crystal oxide semiconductor film is CAAC-OS (C Axis Aligned Cry).
Stallline Oxide Semiconductor) film, polycrystalline oxide semiconductor film, microcrystalline oxide semiconductor film, amorphous oxide semiconductor film, etc.

First, the CAAC-OS film will be described.

The CAAC-OS film is one of the oxide semiconductor films having a plurality of c-axis oriented crystal portions.

Transmission electron microscope (TEM: Transmission Elec) through CAAC-OS membrane
When observed by a TRON Microscope), it is not possible to confirm a clear boundary between crystal portions, that is, a grain boundary (also referred to as a grain boundary). Therefore, C
It can be said that the AAC-OS film is unlikely to cause a decrease in electron mobility due to grain boundaries.

When the CAAC-OS film is observed by TEM from a direction substantially parallel to the sample surface (cross-section TEM observation), it can be confirmed that the metal atoms are arranged in layers in the crystal portion. Each layer of the metal atom has a shape that reflects the unevenness of the surface (also referred to as the formed surface) or the upper surface of the CAAC-OS film, and is arranged in parallel with the formed surface or the upper surface of the CAAC-OS film. ..

On the other hand, the CAAC-OS film is observed by TEM from a direction substantially perpendicular to the sample surface (plane T).
By EM observation), it can be confirmed that the metal atoms are arranged in a triangular or hexagonal shape in the crystal portion. However, there is no regularity in the arrangement of metal atoms between different crystal parts.

From the cross-sectional TEM observation and the planar TEM observation, it can be seen that the crystal portion of the CAAC-OS film has orientation.

In the present specification, "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. Also,"
"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.

In addition, most of the crystal portions contained in the CAAC-OS film have a size that fits in a cube having a side of less than 100 nm. Therefore, the crystal portion contained in the CAAC-OS film has 10 sides.
It also includes cases of a size that fits in a cube of less than nm, less than 5 nm, or less than 3 nm. However, one large crystal region may be formed by connecting a plurality of crystal portions contained in the CAAC-OS film. For example, in a flat TEM image, 2500 nm ² or more, 5 μm
Crystal regions of ² or more or 1000 μm ² or more may be observed.

X-ray diffraction (XRD: X-Ray Diffraction) with respect to the CAAC-OS film
When structural analysis is performed using the device, for example, CAAC-OS having crystals of InGaZnO ₄
In the analysis of the film by the out-of-plane method, a peak may appear in the vicinity of the diffraction angle (2θ) of 31 °. Since this peak is attributed to the (009) plane of the InGaZnO ₄ crystal, the crystal of the CAAC-OS film has c-axis orientation, and the c-axis is oriented substantially perpendicular to the surface to be formed or the upper surface. It can be confirmed that it is.

On the other hand, in-p in which X-rays are incident on the CAAC-OS film from a direction substantially perpendicular to the c-axis.
In the analysis by the lane method, a peak may appear in the vicinity of 2θ at 56 °. This peak is attributed to the (110) plane of the crystal of InGaZnO ₄ . In the case of a single crystal oxide semiconductor film of InGaZnO ₄ , 2θ is fixed in the vicinity of 56 °, and the normal vector of the sample surface is the axis (φ axis).
When the analysis (φ scan) is performed while rotating the sample, 6 peaks attributed to the crystal plane equivalent to the (110) plane are observed. On the other hand, in the case of the CAAC-OS film, a clear peak does not appear even when 2θ is fixed in the vicinity of 56 ° and φ scan is performed.

From the above, in the CAAC-OS film, the orientation of the a-axis and the b-axis is irregular between different crystal portions, but the orientation is c-axis, and the c-axis is the normal of the surface to be formed or the upper surface. It can be seen that the direction is parallel to the vector. Therefore, each layer of the metal atoms arranged in layers confirmed by the above-mentioned cross-sectional TEM observation is a plane parallel to the ab plane of the crystal.

The crystal portion is formed when a CAAC-OS film is formed or when a crystallization treatment such as a heat treatment is performed. As described above, the c-axis of the crystal is oriented in a direction parallel to the normal vector of the surface to be formed or the upper surface of the CAAC-OS film. Therefore, for example, when the shape of the CAAC-OS film is changed by etching or the like, the c-axis of the crystal may not be parallel to the normal vector of the surface to be formed or the upper surface of the CAAC-OS film.

Further, in the CAAC-OS film, the distribution of the crystal portions oriented on the c-axis may not be uniform. For example, when the crystal portion of the CAAC-OS film is formed by crystal growth from the vicinity of the upper surface of the CAAC-OS film, the region near the upper surface is the ratio of the crystal portion oriented on the c-axis rather than the region near the surface to be formed. May be high. Further, when impurities are added to the CAAC-OS film, the regions to which the impurities are added may be altered to form regions having different proportions of crystal portions that are partially c-axis oriented.

The out-of-plane of the CAAC-OS film having InGaZnO ₄ crystals.
In the analysis by the method, in addition to the peak near 31 ° in 2θ, the peak may appear near 36 ° in 2θ. The peak in which 2θ is in the vicinity of 36 ° indicates that a part of the CAAC-OS film contains crystals having no c-axis orientation. In the CAAC-OS film, it is preferable that 2θ shows a peak near 31 ° and 2θ does not show a peak near 36 °.

The CAAC-OS film is an oxide semiconductor film having a low impurity concentration. Impurities are elements other than the main components of the oxide semiconductor film, such as hydrogen, carbon, silicon, and transition metal elements. In particular, elements such as silicon, which have a stronger bond with oxygen than the metal elements constituting the oxide semiconductor film, disturb the atomic arrangement of the oxide semiconductor film by depriving the oxide semiconductor film of oxygen and have crystalline properties. It becomes a factor to reduce. In addition, heavy metals such as iron and nickel, argon, carbon dioxide, etc. have a large atomic radius (or molecular radius), so if they are contained inside the oxide semiconductor film, they disturb the atomic arrangement of the oxide semiconductor film and become crystalline. It becomes a factor to reduce. Impurities contained in the oxide semiconductor film may become a carrier trap or a carrier generation source.

The CAAC-OS film is an oxide semiconductor film having a low defect level density. For example, oxygen deficiency in an oxide semiconductor film may become a carrier trap or a carrier generation source by capturing hydrogen.

A low impurity concentration and a low defect level density (less oxygen deficiency) is called high-purity intrinsic or substantially high-purity intrinsic. Oxide semiconductor films having high-purity intrinsics or substantially high-purity intrinsics have few carrier sources, so that the carrier density can be lowered. Therefore, the transistor using the oxide semiconductor film rarely has electrical characteristics (also referred to as normally on) in which the threshold voltage becomes negative. Further, the oxide semiconductor film having high purity intrinsicity or substantially high purity intrinsicity has few carrier traps. Therefore, the transistor using the oxide semiconductor film has a small fluctuation in electrical characteristics and is a highly reliable transistor. The charge captured by the carrier trap of the oxide semiconductor film takes a long time to be released, and may behave as if it were a fixed charge. Therefore, a transistor using an oxide semiconductor film having a high impurity concentration and a high defect level density may have unstable electrical characteristics.

Further, the transistor using the CAAC-OS film has a small fluctuation in electrical characteristics due to irradiation with visible light or ultraviolet light.

Next, the microcrystalline oxide semiconductor film will be described.

In the microcrystal oxide semiconductor film, the crystal portion may not be clearly confirmed in the observation image by TEM. The crystal part contained in the microcrystalline oxide semiconductor film often has a size of 1 nm or more and 100 nm or less, or 1 nm or more and 10 nm or less. In particular, 1 nm or more and 10 n
Nanocrystals (nc: nanocrys) that are microcrystals of m or less, or 1 nm or more and 3 nm or less.
An oxide semiconductor film having tal) is used as an nc-OS (nanocrystalline O).
It is called a xide Semiconductor) membrane. Further, the nc-OS film is, for example, T.
It may not be possible to clearly confirm the grain boundaries in the observation image by EM.

The nc-OS film 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). In addition, the nc-OS film does not show regularity in crystal orientation between different crystal portions. Therefore, no orientation is observed in the entire film.
Therefore, the nc-OS film may be indistinguishable from the amorphous oxide semiconductor film depending on the analysis method. For example, an XRD that uses X-rays having a diameter larger than that of the crystal portion for an nc-OS film.
When the structural analysis is performed using the apparatus, the peak indicating the crystal plane is not detected in the analysis by the out-of-plane method. Further, electron diffraction using an electron beam having a probe diameter (for example, 50 nm or more) larger than that of the crystal portion with respect to the nc-OS film (also referred to as limited field electron diffraction).
When this is done, a diffraction pattern such as a halo pattern is observed. On the other hand, when electron diffraction (also referred to as nanobeam electron diffraction) is performed on the nc-OS film using an electron beam having a probe diameter (for example, 1 nm or more and 30 nm or less) that is close to the size of the crystal portion or smaller than the crystal portion. Spots are observed. Further, when nanobeam electron diffraction is performed on the nc-OS film, a region having high brightness (in a ring shape) may be observed in a circular motion. Further, when nanobeam electron diffraction is performed on the nc-OS film, a plurality of spots may be observed in the ring-shaped region.

The nc-OS film is an oxide semiconductor film having higher regularity than the amorphous oxide semiconductor film. Therefore, the nc-OS film has a lower defect level density than the amorphous oxide semiconductor film. However, in the nc-OS film, there is no regularity in the crystal orientation between different crystal portions. Therefore, nc-
The OS film has a higher defect level density than the CAAC-OS film.

The oxide semiconductor film may be, for example, an amorphous oxide semiconductor film, a microcrystalline oxide semiconductor film, or C.
Among the AAC-OS films, a laminated film having two or more kinds may be used.

As the oxide semiconductor film contained in the transistor and the capacitive element of the semiconductor device of one aspect of the present invention, any of the above-mentioned crystalline state oxide semiconductor films may be applied. Further, when the oxide semiconductor film having a laminated structure is included, the crystal state of each oxide semiconductor film may be different. However, it is preferable to apply the CAAC-OS film to the oxide semiconductor film that functions as the channel region of the transistor. Further, since the oxide semiconductor film functioning as an electrode of the capacitive element has a higher impurity concentration than the oxide semiconductor film contained in the transistor, the crystallinity may be reduced.

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

(Embodiment 7)
In the present embodiment, a display device using the semiconductor device of one aspect of the present invention will be described with reference to FIG. The same parts as those shown in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The display device shown in FIG. 12A has a region having pixels of the display element (hereinafter referred to as a pixel unit 302) and a circuit unit (hereinafter referred to as a pixel unit 302) having a circuit arranged outside the pixel unit 302 to drive the pixels.
Hereinafter, a circuit having a drive circuit unit 304 and an element protection function (hereinafter, protection circuit 30).
6) and a terminal portion 307. The protection circuit 306 may not be provided.

It is desirable that a part or all of the drive circuit unit 304 is formed on the same substrate as the pixel unit 302. This makes it possible to reduce the number of parts and the number of terminals. Drive circuit unit 304
When a part or all of the above is not formed on the same substrate as the pixel part 302, a part or all of the drive circuit part 304 may be COG (Chip On Glass) or TAB (T).
It can be implemented by ape Automated Bonding).

The pixel unit 302 has a circuit (hereinafter referred to as a pixel circuit 301) 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 304 is a circuit for outputting a signal (scanning signal) for selecting a pixel (hereinafter referred to as a gate driver 304a), and a circuit for supplying a signal (data signal) for driving a display element of the pixel (hereinafter referred to as a gate driver 304a). Hereinafter, it has a drive circuit such as a source driver 304b).

The gate driver 304a has a shift register and the like. The gate driver 304a
A signal for driving the shift register is input via the terminal unit 307, and the signal is output. For example, the gate driver 304a receives a start pulse signal, a clock signal, and the like, and outputs a pulse signal. The gate driver 304a 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 304a may be provided, and the scanning lines GL_1 to GL_X may be divided and controlled by the plurality of gate drivers 304a. Alternatively, the gate driver 304a has a function of being able to supply an initialization signal. However, the present invention is not limited to this, and the gate driver 30
4a can also supply another signal.

The source driver 304b has a shift register and the like. The source driver 304b
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 307. The source driver 304b has a function of generating a data signal to be written in the pixel circuit 301 based on the image signal. Further, the source driver 304b has a function of controlling the output of the data signal according to the pulse signal obtained by inputting the start pulse, the clock signal and the like. Further, the source driver 304b 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 304b has a function of being able to supply an initialization signal. However, the present invention is not limited to this, and the source driver 304b can also supply another signal.

The source driver 304b is configured by using, for example, a plurality of analog switches.
The source driver 304b 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 304b may be configured by using a shift register or the like.

In each of the plurality of pixel circuits 301, the 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 301, the writing and holding of the data of the data signal is controlled by the gate driver 304a. For example, in the pixel circuit 301 in the mth row and nth column, a pulse signal is input from the gate driver 304a 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 304b via (n is a natural number equal to or less than Y).

The protection circuit 306 shown in FIG. 12A is, for example, a gate driver 304a and a pixel circuit 3
It is connected to the scanning line GL, which is the wiring between 01. Alternatively, the protection circuit 306 is connected to the data line DL, which is the wiring between the source driver 304b and the pixel circuit 301. Alternatively, the protection circuit 306 can be connected to the wiring between the gate driver 304a and the terminal portion 307. Alternatively, the protection circuit 306 can be connected to the wiring between the source driver 304b and the terminal portion 307. The terminal portion 307 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 306 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 306 is connected.

As shown in FIG. 12A, the protection circuit 30 is attached to the pixel unit 302 and the drive circuit unit 304, 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 306 is not limited to this, and for example, the configuration may be such that the protection circuit 306 is connected to the gate driver 304a or the protection circuit 306 is connected to the source driver 304b. Alternatively, the protection circuit 306 may be connected to the terminal portion 307.

Further, FIG. 12A shows an example in which the drive circuit unit 304 is formed by the gate driver 304a and the source driver 304b, but the present invention is not limited to this configuration. For example, a configuration may be configured in which only the gate driver 304a 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 301 shown in FIG. 12A can be configured as shown in FIG. 12B, for example.

The pixel circuit 301 shown in FIG. 12B includes a liquid crystal element 370, a transistor 150, and a capacitive element 160. As the transistor 150 and the capacitive element 160, the semiconductor device having the configuration of FIG. 1 shown in the first embodiment can be used.

The potential of one of the pair of electrodes of the liquid crystal element 370 is appropriately set according to the specifications of the pixel circuit 301. The orientation state of the liquid crystal element 370 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 370 of each of the plurality of pixel circuits 301. Further, different potentials may be applied to one of the pair of electrodes of the liquid crystal element 370 of the pixel circuit 301 in each row.

For example, as a method of driving a display device including a liquid crystal element 370, 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)
fluid Crystal 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.

Further, the liquid crystal element may be composed of a liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent. The liquid crystal showing the blue phase has a short response speed of 1 msec or less. Further, since the liquid crystal showing the blue phase is optically isotropic, no alignment treatment is required.
Moreover, the viewing angle dependence is small.

In the pixel circuit 301 in the m-th row and n-th column, one of the source electrode or the drain electrode of the transistor 150 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 370. To. Further, the gate electrode of the transistor 150 is a scanning line G.
It is electrically connected to L_m. The transistor 150 has a function of controlling data writing of a data signal by turning it on or off.

One of the pair of electrodes of the capacitive element 160 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 370. The potential value of the potential supply line VL is appropriately set according to the specifications of the pixel circuit 301. The capacitance element 160 has a function as a holding capacitance for holding the written data.

For example, in the display device having the pixel circuit 301 of FIG. 12A, the gate driver 304
The pixel circuit 301 of each row is sequentially selected by a, the transistor 150 is turned on, and the data of the data signal is written.

The pixel circuit 301 to which the data is written is put into a holding state when the transistor 150 is turned off. By doing this sequentially line by line, the image can be displayed.

Although an example in which a liquid crystal element 370 is used as the display element is shown, one aspect of the embodiment of the present invention is not limited to this.

For example, in the present specification and the like, the display element, the display device which is a device having a display element, the light emitting element, and the light emitting device which is a device having a light emitting element use various forms or have various elements. Can be done. As an example of a display element, a display device, a light emitting element or a light emitting device, an EL (electroluminescence) element (EL element containing organic and inorganic substances, organic E)
L element, inorganic EL element), LED (white LED, red LED, green LED, blue LED, etc.), transistor (transistor that emits light according to current), electron emitting element, liquid crystal element,
Electronic ink, electrophoretic element, grating light valve (GLV), plasma display (PDP), MEMS (micro electro mechanical system), digital micromirror device (DMD), DMS (digital micro shutter), IM
By electromagnetic action such as OD (interference modulation) element, electrowetting element, piezoelectric ceramic display, carbon nanotube, etc.
Some have a display medium in which contrast, brightness, reflectance, transmittance, etc. change. EL
An EL display or the like is an example of a display device using an element. As an example of a display device using an electron emitting element, a field emission display (FED) or SE
D method flat display (SED: Surface-conduction Elec)
Tron-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). An example of a display device using electronic ink or an electrophoresis element is electronic paper.

FIG. 21 shows an example in which a liquid crystal element is used as the display element. The substrate 102a is provided with a common electrode 124. A liquid crystal layer 123 is provided between the common electrode 124 and the conductive film 120.

Alternatively, FIG. 22 shows an example in which a light emitting element is used as the display element. An insulating film 132, a light emitting layer 125, and a common electrode 124 are provided on the conductive film 120.

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, a display module and an electronic device using the semiconductor device of one aspect of the present invention will be described with reference to FIGS. 13 and 14.

The display module 8000 shown in FIG. 13 has a touch panel 8004 connected to the FPC8003, a display panel 8006 connected to the FPC8005, a backlight unit 8007, a frame 8009, and a printed circuit board 8010 between the upper cover 8001 and the lower cover 8002. It has a 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 unit 8007 has a light source 8008. The light source 8008 may be provided at the end of the backlight unit 8007 and may use a light diffusing plate.

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. Battery 801
1 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.

14 (A) to 14 (H) are views showing electronic devices. These electronic devices include a housing 5000, a display unit 5001, a speaker 5003, an LED lamp 5004, and an operation key 50.
05 (including power switch or operation switch), connection terminal 5006, sensor 5007 (including power switch)
Force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, voice, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, (Including the function of measuring vibration, odor or infrared rays), microphone 5008, etc. can be provided.

FIG. 14A is a mobile computer, in addition to the one described above, switch 5009.
, Infrared port 5010, etc. can be provided. FIG. 14B is a portable image reproduction device (for example, a DVD reproduction device) provided with a recording medium, and may have a second display unit 5002, a recording medium reading unit 5011, and the like in addition to those described above. can. FIG. 14C shows a goggle type display, in addition to the above-mentioned one, the second display unit 5002 and the support unit 5012.
, Earphones 5013, etc. can be provided. FIG. 14 (D) is a portable gaming machine, which may have a recording medium reading unit 5011 and the like in addition to those described above. FIG. 14E is a digital camera with a television image receiving function, which may have an antenna 5014, a shutter button 5015, an image receiving unit 5016, and the like, in addition to those described above. FIG. 14 (F) is a portable gaming machine, and in addition to those described above, the second display unit 5002 and the recording medium reading unit 5011.
, Etc. can be possessed. FIG. 14 (G) is a television receiver, in addition to the one described above.
It can have a tuner, an image processing unit, and the like. FIG. 14 (H) is a portable television receiver, and in addition to the above-mentioned one, a charger 5017 capable of transmitting and receiving signals and the like can be provided.

The electronic devices shown in FIGS. 14 (A) to 14 (H) 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 function to display a calendar, date or time, etc., a function to control processing by various software (programs), Wireless communication function, function to connect to various computer networks using wireless communication function, function to transmit or receive various data using wireless communication function, program or data recorded on recording medium to be read and displayed It can have a function of displaying on a unit, and the like. Further, in an electronic device having a plurality of display units, a function of mainly displaying image information on one display unit and mainly displaying character information on another display unit, or consideration of parallax on a plurality of display units. It is possible to have a function of displaying a three-dimensional image by displaying the image. Further, in an electronic device having an image receiving unit, a function of shooting a still image, a function of shooting a moving image, a function of automatically or manually correcting the shot image, and a function of recording the shot image as a recording medium (external or built in the camera). It can have a function of saving, a function of displaying a captured image on a display unit, and the like. It should be noted that FIGS. 14 (A) to 1
The functions that the electronic device shown in 4 (H) can have are not limited to these, and can have various functions.

The electronic device described in the present embodiment is characterized by having a display unit for displaying some information.

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

102 Substrate 102a Substrate 104a Oxide semiconductor film 104b Oxide semiconductor film 106 Insulation film 107 Insulation film 108 Insulation film 110a Oxide semiconductor film 110b Oxide semiconductor film 112a Source electrode 112b Drain electrode 114 Insulation film 116 Insulation film 118 Insulation film 118a Insulation Film 120 Conductive 120a Conductive 121 Conductive 121a Conductive 122 Insulating film 132 Insulating film 140 Opening 142 Opening 150 Transistor 151 Transistor 152 Transistor 160 Capacitive element 161 Capacitive element 162 Capacitive element 202 Substrate 204 Oxide semiconductor film 204a Oxide semiconductor film 204b Oxide semiconductor film 206 Insulation film 207 Insulation film 208 Insulation film 210 Oxide semiconductor film 212a Source electrode 212b Drain electrode 216 Insulation film 217 Insulation film 218 Insulation film 220 Conductive film 240 Opening 250 Transistor 260 Capacitive element 301 Pixel circuit 302 Pixel part 304 Drive circuit part 304a Gate driver 304b Source driver 306 Protection circuit 307 Terminal part 370 Liquid crystal element 410a Oxide laminated film 410b Oxide laminated film 420 Oxide semiconductor film 420a Oxide semiconductor film 420b Oxide semiconductor film 422 Oxide film 422a Oxidation Material film 422b Oxide film 5000 Housing 5001 Display unit 5002 Display unit 5003 Speaker 5004 LED lamp 5005 Operation key 5006 Connection terminal 5007 Sensor 5008 Microphone 5009 Switch 5010 Infrared port 5011 Recording medium reading unit 5012 Support unit 5013 Earphone 5014 Antenna 5015 Shutter button 5016 Image receiver 5017 Charger 8000 Display module 8001 Top cover 8002 Bottom cover 8003 FPC
8004 touch panel 8005 FPC
8006 Display panel 8007 Backlight unit 8008 Light source 8009 Frame 8010 Printed circuit board 8011 Battery

Claims (3)

The first conductive film and
A first oxide semiconductor film arranged above the first conductive film via a first insulating film and having a channel forming region of a transistor, and a first oxide semiconductor film.
The second oxide semiconductor film above the first insulating film and
A second conductive film and a third conductive film electrically connected to the first oxide semiconductor film,
A fourth conductive film arranged above the first oxide semiconductor film via the second insulating film and having an overlap with the channel forming region, and a fourth conductive film.
It has a pixel electrode arranged above the third conductive film and electrically connected to the third conductive film.
The second oxide semiconductor film has a first region in a region where the upper surface is in contact with the third insulating film and which overlaps with the pixel electrode via the third insulating film. Have and
The second oxide semiconductor film has a second region whose upper surface is in contact with the second insulating film.
The third insulating film is arranged above the second insulating film.
The second oxide semiconductor film does not have a region in contact with the pixel electrode, and the second oxide semiconductor film does not have a region in contact with the pixel electrode.
In a cross-sectional view, the first region is a semiconductor device having a smaller distance from the pixel electrode than the second region. The first conductive film and
A first oxide semiconductor film arranged above the first conductive film via a first insulating film and having a channel forming region of a transistor, and a first oxide semiconductor film.
The second oxide semiconductor film above the first insulating film and
A second conductive film and a third conductive film electrically connected to the first oxide semiconductor film,
A fourth conductive film arranged above the first oxide semiconductor film via the second insulating film and having an overlap with the channel forming region, and a fourth conductive film.
It has a pixel electrode arranged above the third conductive film and electrically connected to the third conductive film.
The second oxide semiconductor film has a first region in a region where the upper surface is in contact with the third insulating film and which overlaps with the pixel electrode via the third insulating film. Have and
The second oxide semiconductor film has a second region whose upper surface is in contact with the second insulating film.
The third insulating film is arranged above the second insulating film.
The second oxide semiconductor film does not have a region in contact with the pixel electrode, and the second oxide semiconductor film does not have a region in contact with the pixel electrode.
In the cross-sectional view, the first region has a smaller distance from the pixel electrode than the second region.
The first region has a function as a first electrode of the capacitive element, and has a function as a first electrode.
The pixel electrode is a semiconductor device having a function as a second electrode of the capacitive element. In claim 1 or 2,
The first oxide semiconductor film and the second oxide semiconductor film are semiconductor devices containing In, Ga, and Zn as main components.

Images