Manufacturing method for semiconductor device

Abstract

To provide a manufacturing method for a semiconductor device for increasing the reliability by making a semiconductor device with an oxide semiconductor have stable electrical characteristics.SOLUTION: In this method, an oxide semiconductor film is heated in an inert gas atmosphere and then the oxide semiconductor film is heated in an oxygen atmosphere. By this step, impurities such as hydrogen, moisture, a hydroxyl group, or a hydride can be eliminated on purpose from the oxide semiconductor film, so that the oxide semiconductor film can have higher purity. When the impurities are eliminated, oxygen, which is a main component material of the oxide semiconductor, may become deficient but oxygen can be supplied by the heating in the oxygen atmosphere.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.

[0002] In this specification, a semiconductor device is a device that can function by utilizing semiconductor characteristics. Generally speaking, electro-optical devices, semiconductor circuits, and electronic devices are all semiconductor devices. [Background technology]

[0003] A transistor (thin film transistor) is made using a semiconductor thin film formed on a substrate with an insulating surface. The technology of constructing thin-film transistors (also called TFTs) is attracting attention. It is widely used in electronic devices such as ICs and image display devices. Silicon-based semiconductor materials are widely known as semiconductor thin films that can be used in transistors. As another material, oxide semiconductors are attracting attention.

[0004] For example, a semiconductor with an electron carrier concentration of 10 18 / cm 3 is less than Amorphous oxide containing indium (In), gallium (Ga), and zinc (Zn) was used. A transistor is disclosed (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-165528 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the thin film formation process of oxide semiconductors, the stoichiometric composition is affected by factors such as excess or deficiency of oxygen. If there is a deviation from the normal state or if hydrogen or moisture that forms electron donors gets mixed in, the electrical conductivity This phenomenon is a major problem for transistors using oxide semiconductors. This is a factor that affects the mechanical properties of the material.

[0007] In view of such problems, a semiconductor device using an oxide semiconductor has been provided with stable electrical characteristics. One of the objectives is to improve reliability.

[0008] In addition, the present invention aims to prevent the occurrence of a parasitic channel on the back channel side of an oxide semiconductor film. It shall be one. [Means for solving the problem]

[0009] In order to suppress fluctuations in the electrical characteristics of a transistor including an oxide semiconductor film, Impurities such as hydrogen, moisture, a hydroxyl group, or a hydride (also called a hydrogen compound) are added to the oxide semiconductor film. Oxide semiconductors that are intentionally removed and simultaneously reduced by the impurity removal process By supplying oxygen, which is the main component of the oxide semiconductor film, the oxide semiconductor film can be highly purified and It also becomes electrically I-type (intrinsic).

[0010] An I-type (intrinsic) oxide semiconductor is an oxide semiconductor that has had hydrogen, an n-type impurity, removed from it. By purifying the semiconductor to the maximum extent possible so that it contains no impurities other than the main component, the I type ( i-type (intrinsic) oxide semiconductor or an oxide semiconductor that is as close to i-type (intrinsic) as possible. In other words, instead of adding impurities to make it I-type, impurities such as hydrogen and water are removed as much as possible. This makes it possible to produce a highly purified I-type (intrinsic semiconductor) or something close to it. By doing so, the Fermi level (Ef) is set to the same level as the intrinsic Fermi level (Ei). It can be up to 100%.

[0011] In a transistor including an oxide semiconductor film, An oxide layer is formed to prevent charging on the back channel side of the An oxide layer is formed on the oxide layer by introducing (adding) an oxide, and a heat treatment is then performed. This may be done before forming an insulating layer on the oxide layer.

[0012] The oxide layer for preventing charging is an oxide semiconductor film, preferably a highly purified oxide semiconductor film. It is provided on the back channel side of the conductor film (the side opposite to the gate insulating film) and is more dielectric than the oxide semiconductor. For example, an oxide layer having a dielectric constant of 8 to 20 is used.

[0013] The oxide layer is thicker than the oxide semiconductor film. The thickness of the oxide layer is set to 3 nm or more and 30 nm or less, and the oxide layer has a thickness of more than 10 nm and is It is preferable that the thickness of the insulating film is equal to or larger than the thickness of the semiconductor film.

[0014] The oxide layer may be made of a metal oxide. Gallium oxide, or gallium oxide with indium or zinc added at 0.01 to 5 atomic percent. can be used.

[0015] The above-mentioned oxygen introduction and heating process produces hydrogen, moisture, hydroxyl groups, or hydrides (hydrogen compounds and The oxide semiconductor film is highly purified by intentionally removing impurities such as SiO 2 and SiO 2 from the oxide semiconductor film. The introduction of oxygen reduces the bond between the metal and hydrogen that constitutes the oxide semiconductor, or The bonds between the metal and the hydroxyl groups are broken, and these hydrogen or hydroxyl groups react with oxygen. The water is produced by the process, and the impurities, hydrogen and can facilitate the elimination of the hydroxyl group as water.

[0016] Since oxygen is introduced into the oxide semiconductor film through the laminated metal oxide film, the introduction of oxygen is The depth of introduction (introduction region) can be controlled, and oxygen can be efficiently introduced into the oxide semiconductor film. It is possible.

[0017] In addition, since the heat treatment is performed in a state where the metal oxide film containing oxygen is in contact with the oxide semiconductor film, One of the main components of oxide semiconductors that is reduced during the process of removing impurities The oxygen can be supplied to the oxide semiconductor film from the metal oxide film containing oxygen. As a result, the oxide semiconductor film becomes more highly purified and electrically i-type (intrinsic).

[0018] In addition, after the heat treatment, impurities such as moisture and hydrogen are prevented from re-entering the oxide semiconductor film. A protective insulating layer is further formed on the insulating layer to block these substances from entering from the outside. You may do so.

[0019] A transistor including a highly purified oxide semiconductor film has a low threshold voltage, an on-state current, and the like. The electrical characteristics are almost temperature-independent. In addition, the transistor characteristics are not affected by light degradation. There is also little fluctuation.

[0020] In this way, a transistor having an oxide semiconductor film that has been highly purified and made electrically i-type (intrinsic) is manufactured. The electrical characteristic fluctuation of the sintered body is suppressed, and the sintered body is electrically stable. It is possible to provide a highly reliable semiconductor device using an oxide semiconductor having such characteristics.

[0021] The temperature of the heat treatment is 250°C to 650°C, or 450°C to 600°C, or The heat treatment is performed in an atmosphere of nitrogen, oxygen, or ultra-dry air (water content 20ppm). pm or less, preferably 1 ppm or less, preferably 10 ppb or less of air), or rare gases The reaction may be carried out under an atmosphere of nitrogen (argon, helium, etc.).

[0022] One embodiment of the present invention disclosed in this specification is a gate electrode formed on a substrate, A gate insulating film is formed to cover the gate electrode, and an oxide is formed in the region overlapping the gate electrode via the gate insulating film. A semiconductor film is formed, a source electrode and a drain electrode are formed on the oxide semiconductor film, and an oxide A metal oxide film is formed in contact with the semiconductor film and covers the source electrode and the drain electrode, The oxygen is introduced into at least one of the interface between the oxide semiconductor film and the metal oxide film, the metal oxide film, or the oxide semiconductor film and the metal oxide film. The present invention relates to a method for manufacturing a semiconductor device, and a method thereof. do.

[0023] In addition, another embodiment of the present invention disclosed in this specification is a gate electrode formed on a substrate, A gate insulating film is formed to cover the gate electrode, and a region overlapping the gate electrode via the gate insulating film is formed. and forming a source electrode and a drain electrode on the oxide semiconductor film. a metal oxide film is formed in contact with the oxide semiconductor film and covers the source electrode and the drain electrode; An insulating film is formed to cover the metal oxide film, and the oxide semiconductor film, the metal oxide film, or the oxide semiconductor film is formed. and introducing oxygen into at least one of the interfaces between the semiconductor device and the metal oxide film, and then subjecting the semiconductor device to a heat treatment. This is the manufacturing method.

[0024] In addition, another embodiment of the present invention disclosed in this specification is a gate electrode formed on a substrate, A gate insulating film is formed to cover the gate electrode, and a region overlapping the gate electrode via the gate insulating film is formed. The oxide semiconductor film is heated in an inert atmosphere and subjected to oxygen treatment. A first heat treatment including cooling under an atmosphere is performed, and a source electrode and a drain electrode are formed on the oxide semiconductor film. A metal oxide film is formed on the source electrode and the drain electrode. and forming a semiconductor oxide film, a metal oxide film, or a mixture of a semiconductor oxide film and a metal oxide film. Oxygen is introduced into at least one of the interfaces to form an insulating film covering the metal oxide film, and a second heat treatment is performed. The present invention relates to a method for manufacturing a semiconductor device that performs a semiconductor device process.

[0025] In addition, another embodiment of the present invention disclosed in this specification is a gate electrode formed on a substrate, A gate insulating film is formed to cover the gate electrode, and a region overlapping the gate electrode via the gate insulating film is formed. The oxide semiconductor film is heated in an inert atmosphere and subjected to oxygen treatment. A first heat treatment including cooling under an atmosphere is performed, and a source electrode and a drain electrode are formed on the oxide semiconductor film. A metal oxide film is formed on the source electrode and the drain electrode. and forming an insulating film covering the metal oxide film, and oxygen is introduced into at least one of the interfaces between the oxide semiconductor film and the metal oxide film; and a second heat treatment is performed. The present invention relates to a method for manufacturing a semiconductor device that performs a semiconductor device process.

[0026] In the method for manufacturing a semiconductor device, the metal oxide film may be a film containing gallium oxide. It is preferable to form

[0027] Alternatively, in the above-mentioned method for manufacturing a semiconductor device, the metal oxide film may be formed of indium or zinc. A gallium oxide film containing 0.01 to 5 atomic % of lead may be formed.

[0028] In the above-described method for manufacturing a semiconductor device, the temperature of the heat treatment is set to 450° C. to 600° C. It is preferable to do so.

[0029] In the above-described method for manufacturing a semiconductor device, the oxide semiconductor film may include It is preferable to form a film containing sodium.

[0030] In the above structure, it is preferable to use a gallium oxide film as the metal oxide film. Gallium oxide films can be obtained by sputtering, CVD, vapor deposition, etc. has an energy gap of approximately 4.9 eV, depending on the composition ratio of oxygen and gallium. , and has translucency in the visible light region.

[0031] In this specification, gallium oxide may be expressed as GaOx (x>0). For example, Ga When Ox has a crystal structure, Ga2O3 with x=1.5 is known.

[0032] In the above structure, before a metal oxide film is formed over the oxide semiconductor film, Heat treatment may be performed. The oxygen is introduced by ion implantation or ion doping. This can be done using Effect of the Invention

[0033] A metal oxide film is formed on and in contact with the oxide semiconductor film, oxygen is introduced through the metal oxide film, and This oxygen introduction and heating process removes hydrogen, moisture, hydroxyl groups, hydrides, etc. It is possible to intentionally remove impurities from an oxide semiconductor film to highly purify the oxide semiconductor film. A transistor having an oxide semiconductor film that is highly purified and electrically i-type (intrinsic) can be obtained. The electrical characteristic fluctuation is suppressed, and the device is electrically stable.

[0034] Therefore, in one embodiment of the present invention, a transistor with stable electrical characteristics can be manufactured. Cut.

[0035] Another embodiment of the present invention is a semiconductor device including a transistor with favorable electrical characteristics and high reliability. It is possible to create a device. [Brief description of the drawings]

[0036] [Figure 1] 1A to 1C illustrate one embodiment of a semiconductor device and a manufacturing method thereof; [Diagram 2] 1A to 1C illustrate one embodiment of a semiconductor device. [Diagram 3] 1A to 1C illustrate one embodiment of a semiconductor device. [Figure 4] 1A to 1C illustrate one embodiment of a semiconductor device. [Diagram 5] 1A to 1C illustrate one embodiment of a semiconductor device. [Figure 6] 1A to 1C illustrate one embodiment of a semiconductor device. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] (A) Model diagram showing the laminated structure of the dielectric. (B) Equivalent circuit diagram. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following description, and various modifications in form and details are possible by those skilled in the art. The present invention is not limited to the description of the following embodiments. It is not something that can be done.

[0038] The ordinal numbers such as 1st and 2nd are used for convenience and do not indicate the order of steps or stacking. In addition, the specific names used in this specification are not intended to identify the invention. This does not indicate the

[0039] (Embodiment 1) In this embodiment mode, one mode of a semiconductor device and a manufacturing method of the semiconductor device will be described with reference to FIGS. In this embodiment, a transistor including an oxide semiconductor film is used as an example of a semiconductor device. Shows.

[0040] As shown in FIG. 1E, a transistor 410 is formed on a substrate 400 having an insulating surface. A gate electrode 401, a gate insulating film 402, an oxide semiconductor film 403, a source electrode 405a, A buffer electrode 405b for the oxide semiconductor film 403 is provided on the oxide semiconductor film 403. A metal oxide film 407 and an insulating film 409 are laminated in this order to prevent charging on the channel side. It has been done.

[0041] 1A to 1E illustrate an example of a method for manufacturing the transistor 410. FIG.

[0042] First, a conductive film is formed on a substrate 400 having an insulating surface, and then a first photolithography process is performed. The gate electrode 401 is formed by the process. The resist mask is formed by the ink-jet method. If the resist mask is formed by the inkjet method, a photomask is not required. This reduces manufacturing costs.

[0043] There is no significant limitation on the substrate that can be used for the substrate 400 having an insulating surface. In either case, it is necessary to have heat resistance sufficient to withstand the subsequent heat treatment. A glass substrate, a ceramic substrate, a quartz substrate, a sapphire substrate, or the like can be used. In addition, as long as it has an insulating surface, a single crystal semiconductor substrate such as silicon or silicon carbide, a multi-crystal The semiconductor substrates used are crystalline semiconductor substrates, compound semiconductor substrates such as silicon germanium, and SOI substrates. It is also possible to use a substrate having a semiconductor element thereon.

[0044] A flexible substrate may be used as the substrate 400. The transistor 410 including the oxide semiconductor film 403 may be directly formed on a substrate. A transistor 410 including an oxide semiconductor film 403 is formed on a formation substrate. In order to peel and transfer the film from the production substrate to the flexible substrate, A separation layer may be provided between the substrate and the transistor including the oxide semiconductor film.

[0045] An insulating film serving as a base film may be provided between the substrate 400 and the gate electrode 401. It has a function of preventing the diffusion of impurity elements from the substrate 400, and is a silicon nitride film, a silicon oxide film, The insulating layer is made of one or more films selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film. It can be formed in a laminated structure.

[0046] The gate electrode 401 may be made of molybdenum, titanium, tantalum, tungsten, or aluminum. The material is made of metals such as aluminum, copper, neodymium, scandium, etc., or alloys made of these materials as the main components. The insulating film may be formed as a single layer or a multilayer.

[0047] Next, a gate insulating film 402 is formed on the gate electrode 401. The gate insulating film 402 is A silicon oxide layer, a silicon nitride layer, or a silicon nitride layer is formed by using a plasma CVD method or a sputtering method. A silicon oxynitride layer, a silicon nitride oxide layer, an aluminum oxide layer, an aluminum nitride layer, A single layer of aluminum oxynitride, aluminum oxide nitride, or hafnium oxide is formed. It can be formed by laminating.

[0048] In addition, in the oxide semiconductor film 403 in this embodiment, impurities are removed and the oxide semiconductor film is mainly composed of an oxide semiconductor. By purifying the material to the maximum extent possible, it is possible to minimize the amount of impurities that act as carrier donors other than the components. An intrinsic (i-type) or substantially intrinsic (i-type) oxide semiconductor is used.

[0049] Such highly purified oxide semiconductors are extremely sensitive to interface states or interface charges. Therefore, the interface between the oxide semiconductor film and the gate insulating film is important. In addition, high quality is required for the gate insulating film that contacts the oxide semiconductor.

[0050] For example, high-density plasma CVD using microwaves (e.g., 2.45 GHz frequency) produces dense This is a preferred method for producing gate insulating films because it can form high-quality insulating layers with high dielectric strength. The high-purity oxide semiconductor and the high-quality gate insulating film are in close contact with each other, which reduces the interface state. This is because it is possible to reduce the interfacial characteristics and improve the interfacial properties.

[0051] Of course, if a good insulating layer can be formed as a gate insulating film, sputtering is also possible. Other deposition methods such as the plasma CVD method and the like can be applied. Even if the insulating layer is one in which the film quality of the gate insulating film and the interface characteristics with the oxide semiconductor are modified by In any case, the quality of the gate insulating film is good, and the oxidation Any material may be used as long as it can reduce the interface state density with the solid semiconductor and form a good interface.

[0052] In addition, the gate insulating film 402 and the oxide semiconductor film should preferably not contain hydrogen, a hydroxyl group, or moisture. In order to prevent this, a spare sputtering device is used as a pretreatment for the formation of the oxide semiconductor film. In the heating chamber, the substrate 400 on which the gate electrode 401 is formed or the gate insulating film 402 is formed. The substrate 400 is preheated to remove impurities such as hydrogen and moisture adsorbed on the substrate 400. It is preferable that the exhaust means provided in the preheating chamber is a cryopump. This pre-heating process can be omitted. Also, this pre-heating process can be omitted after the subsequent process. Then, the substrate 400 (metal oxide film) on which the source electrode 405a and the drain electrode 405b are formed is The same process may be carried out before the deposition of the film 407.

[0053] Next, an oxide semiconductor film having a thickness of 3 nm to 30 nm is formed on the gate insulating film 402 by spatulation. If the thickness of the oxide semiconductor film is too large (for example, if the thickness is 5 0 nm or more), there is a risk that the transistor will become normally on. It is preferable to set the film thickness to the above-mentioned value.

[0054] Note that before the oxide semiconductor film is formed by a sputtering method, argon gas is introduced. A reverse sputtering process is carried out to generate plasma, and the powdery material adhering to the surface of the gate insulating film 402 is removed. It is preferable to remove the substances (also called particles or dust). No voltage was applied to the get side, and voltage was applied to the substrate side using an RF power supply in an argon atmosphere. This method generates plasma near the substrate by ionizing it, and modifies the surface. Alternatively, nitrogen, helium, oxygen, etc. may be used.

[0055] The oxide semiconductor used for the oxide semiconductor film is a quaternary metal oxide, In-Sn-G a-Zn-O oxide semiconductors and In-Ga-Zn-O oxides, which are ternary metal oxides Semiconductors, In-Sn-Zn-O oxide semiconductors, In-Al-Zn-O oxide semiconductors, Sn-Ga-Zn-O oxide semiconductor, Al-Ga-Zn-O oxide semiconductor, Sn-A l-Zn-O oxide semiconductors and In-Zn-O oxide semiconductors, which are binary metal oxides , Sn-Zn-O oxide semiconductor, Al-Zn-O oxide semiconductor, Zn-Mg-O oxide oxide semiconductors, Sn-Mg-O oxide semiconductors, In-Mg-O oxide semiconductors, In-G aO-based oxide semiconductors, In-O-based oxide semiconductors, Sn-O-based oxide semiconductors, Zn-O In addition, the oxide semiconductor may contain SiO2. Here, for example, the In-Ga-Zn-O based oxide semiconductor is an oxide semiconductor containing indium (In ), gallium (Ga), and zinc (Zn), and the composition ratio is Also, elements other than In, Ga, and Zn may be included.

[0056] The oxide semiconductor film has the chemical formula InMO3(ZnO) m A thin film expressed as (m>0) Here, M is one selected from Ga, Al, Mn, and Co, or It indicates multiple metal elements. For example, M can be Ga, Ga and Al, Ga and Mn, or G Examples include a and Co.

[0057] When using an In-Ga-Zn-O-based material as an oxide semiconductor, the target to be used is For example, the composition ratio is In2O3:Ga2O3:ZnO=1:1:1 [mol number The oxide target having a ratio of 1:1 can be used. For example, the acid of In2O3:Ga2O3:ZnO=1:1:2 [molar ratio] is A nitride target may also be used.

[0058] In addition, when using an In-Zn-O-based material as an oxide semiconductor, the composition of the target used The composition ratio is In:Zn=50:1-1:2 in atomic ratio (In2O3 In:ZnO=25:1 to 1:4, preferably In:Zn=20:1 to 1:1 (molar ratio) In terms of In2O3:ZnO=10:1 to 1:2), more preferably In:Zn=1 5:1 to 1.5:1 (converted to a molar ratio of In2O3:ZnO = 15:2 to 3:4) For example, the target used for forming an In-Zn-O oxide semiconductor has an atomic ratio of When In:Zn:O=X:Y:Z, Z>1.5X+Y.

[0059] The target filling rate is 90% or more and 100% or less, preferably 95% or more and 99.9% or less. By using a target with a high filling rate, the oxide semiconductor film formed is fine and dense. It can be a dense film.

[0060] In this embodiment, an In-Ga-Zn-O oxide target is used as the oxide semiconductor film. The oxide semiconductor film is formed by a sputtering method using a rare gas (typically, Sputtering in an atmosphere of rare gas, oxygen, or a mixture of rare gas and oxygen The film can be formed by a coating method.

[0061] The sputtering gas used in forming the oxide semiconductor film is hydrogen, water, a hydroxyl group, or water. It is preferable to use a high-purity gas from which impurities such as chlorines have been removed.

[0062] The oxide semiconductor film is formed by holding the substrate 400 in a deposition chamber kept under reduced pressure. The temperature is set to 100° C. or higher and 600° C. or lower, preferably 200° C. or higher and 400° C. or lower. The impurity concentration in the oxide semiconductor film formed by heating the oxide semiconductor film was The damage caused by sputtering can be reduced. While removing the residual moisture in the chamber, a sputtering gas from which hydrogen and moisture have been removed is introduced, and the above-mentioned Using the get, an oxide semiconductor film is formed on the substrate 400. In order to achieve this, adsorption type vacuum pumps, such as cryopumps, ion pumps, and titanium subs, are required. It is preferable to use a suction pump. Also, the exhaust means is a turbo pump. The deposition chamber evacuated using a cryopump may be, for example, For example, hydrogen atoms, water (H2O) and other compounds containing hydrogen atoms (preferably compounds containing carbon atoms) Since impurities such as fluorine and fluorine-containing compounds are exhausted, the impurities contained in the oxide semiconductor film formed in the deposition chamber are The concentration of substances can be reduced.

[0063] As an example of the deposition conditions, the distance between the substrate and the target is 100 mm, and the pressure is 0.6 Pa. The conditions were: DC power supply 0.5kW, oxygen (oxygen flow rate 100%) atmosphere. In addition, when a pulsed DC power supply is used, the powdery substances (particles, etc.) generated during film formation are reduced. This is preferable because it can reduce the amount of adhesion (also referred to as the "friction") and make the film thickness distribution uniform.

[0064] Next, the oxide semiconductor film is subjected to a second photolithography process to form an island-shaped oxide semiconductor film 4. In order to form an island-shaped oxide semiconductor film 441, The resist mask for this purpose may be formed by an ink-jet method. When the film is formed by the injection method, no photomask is used, and therefore the manufacturing cost can be reduced.

[0065] Note that the etching of the oxide semiconductor film here may be performed by dry etching or wet etching. For example, a wet etching method for an oxide semiconductor film may be used. The etching solution that can be used is a mixture of phosphoric acid, acetic acid, and nitric acid. In addition, ITO07N (manufactured by Kanto Chemical Co., Ltd.) may also be used.

[0066] Next, a source electrode and a drain electrode were formed over the gate insulating film 402 and the oxide semiconductor film 441. A conductive film is formed to form the electrode (including the wiring formed in the same layer). The conductive film used for the electrode and the drain electrode is, for example, Al, Cr, Cu, Ta, Ti Metal film containing an element selected from the group consisting of Mo and W, or a metal nitride containing the above elements as components. Films such as titanium nitride film, molybdenum nitride film, and tungsten nitride film can be used. In addition, Ti, Mo, W, etc. may be applied to either or both of the upper and lower sides of the metal film such as Al or Cu. High melting point metal film or metal nitride film (titanium nitride film, molybdenum nitride film, titanium nitride film, etc.) The source and drain electrodes may be formed by laminating a fluorine film. The conductive film may be formed of a conductive metal oxide. Examples of the conductive metal oxide include indium oxide (In2O3), tin oxide (SnO2), zinc oxide (ZnO), indium tin oxide alloy (In2O3—SnO2, abbreviated as ITO), indium zinc oxide alloy (In2O3—ZnO), or those containing silicon oxide in these metal oxide materials. Indium oxide (In2O3), tin oxide (SnO2), zinc oxide (ZnO), indium tin oxide alloy (In2O3—SnO2, abbreviated as ITO), indium zinc oxide alloy (In2O3—ZnO), or those containing silicon oxide in these metal oxide materials. Indium tin oxide alloy (In2O3—SnO2, abbreviated as ITO), indium zinc oxide alloy (In2O3—ZnO), or those containing silicon oxide in these metal oxide materials. Indium tin oxide alloy (In2O3—SnO2, abbreviated as ITO), indium zinc oxide alloy (In2O3—ZnO), or those containing silicon oxide in these metal oxide materials. can be used.

[0067] Note that the materials of the source electrode and the drain electrode are preferably determined in consideration of the electron affinity of the oxide semiconductor used and the electron affinity of the metal oxide film. That is, when the work function of the materials of the source electrode and the drain electrode is W [eV], the electron affinity of the oxide semiconductor is φ1 [eV], and the electron affinity of the metal oxide film is φ2 [eV], φ2 + 0.4 <W <(φ1 + 0.5), preferably, (φ2 + 0.9) <W <(φ1 + 0.4), and it is preferable to satisfy this relationship. For example, if materials with electron affinities of 4.5 eV and 3.5 eV are used as the oxide semiconductor and the metal oxide film, respectively, the materials of the source electrode and the drain electrode are such that their work function is greater than 3.9 eV and less than 5.0 eV, preferably greater than 4.4 eV and less than 4. 9 eV. It is preferable to use a metal or a metal compound. Thus, in the transistor 410, injection of electrons from the source electrode 405a and the drain electrode 405b into the metal oxide film 407 can be prevented, leakage current can be suppressed, and good electrical characteristics can be obtained at the junction of the oxide semiconductor film and the source electrode and the drain electrode. Examples of materials having such a work function include molybdenum nitride and tungsten nitride. Note that these materials are preferable because they are also excellent in terms of heat resistance. Note that these materials are preferable because they are also excellent in terms of heat resistance. preferably, (φ2 + 0.9) <W <(φ1 + 0.4), and it is preferable to satisfy this relationship. For example, if materials with electron affinities of 4.5 eV and 3.5 eV are used as the oxide semiconductor and the metal oxide film, respectively, the materials of the source electrode and the drain electrode are such that their work function is greater than 3.9 eV and less than 5.0 eV, preferably greater than 4.4 eV and less than 4. 9 eV. It is preferable to use a metal or a metal compound. Thus, in the transistor 410, injection of electrons from the source electrode 405a and the drain electrode 405b into the metal oxide film 407 can be prevented, leakage current can be suppressed, and good electrical characteristics can be obtained at the junction of the oxide semiconductor film and the source electrode and the drain electrode. Examples of materials having such a work function include molybdenum nitride and tungsten nitride. Note that these materials are preferable because they are also excellent in terms of heat resistance. 9 eV. It is preferable to use a metal or a metal compound. Thus, in the transistor 410, injection of electrons from the source electrode 405a and the drain electrode 405b into the metal oxide film 407 can be prevented, leakage current can be suppressed, and good electrical characteristics can be obtained at the junction of the oxide semiconductor film and the source electrode and the drain electrode. Examples of materials having such a work function include molybdenum nitride and tungsten nitride. Note that these materials are preferable because they are also excellent in terms of heat resistance. 9 eV. It is preferable to use a metal or a metal compound. Thus, in the transistor 410, injection of electrons from the source electrode 405a and the drain electrode 405b into the metal oxide film 407 can be prevented, leakage current can be suppressed, and good electrical characteristics can be obtained at the junction of the oxide semiconductor film and the source electrode and the drain electrode. Examples of materials having such a work function include molybdenum nitride and tungsten nitride. Note that these materials are preferable because they are also excellent in terms of heat resistance. 9 eV. It is preferable to use a metal or a metal compound. Thus, in the transistor 410, injection of electrons from the source electrode 405a and the drain electrode 405b into the metal oxide film 407 can be prevented, leakage current can be suppressed, and good electrical characteristics can be obtained at the junction of the oxide semiconductor film and the source electrode and the drain electrode. Examples of materials having such a work function include molybdenum nitride and tungsten nitride. Note that these materials are preferable because they are also excellent in terms of heat resistance. In the transistor 410, injection of electrons from the source electrode 405a and the drain electrode 405b into the metal oxide film 407 can be prevented, leakage current can be suppressed, and good electrical characteristics can be obtained at the junction of the oxide semiconductor film and the source electrode and the drain electrode. In the transistor 410, injection of electrons from the source electrode 405a and the drain electrode 405b into the metal oxide film 407 can be prevented, leakage current can be suppressed, and good electrical characteristics can be obtained at the junction of the oxide semiconductor film and the source electrode and the drain electrode. In the transistor 410, injection of electrons from the source electrode 405a and the drain electrode 405b into the metal oxide film 407 can be prevented, leakage current can be suppressed, and good electrical characteristics can be obtained at the junction of the oxide semiconductor film and the source electrode and the drain electrode. In the transistor 410, injection of electrons from the source electrode 405a and the drain electrode 405b into the metal oxide film 407 can be prevented, leakage current can be suppressed, and good electrical characteristics can be obtained at the junction of the oxide semiconductor film and the source electrode and the drain electrode. Examples of materials having such a work function include molybdenum nitride and tungsten nitride. Note that these materials are preferable because they are also excellent in terms of heat resistance. From the above equation, φ2<(φ1+0.1), preferably φ2<(φ1-0.5). However, it is more preferable that the relationship φ2<(φ1-0.9) is satisfied.

[0068] A resist mask is formed on the conductive film by a third photolithography process, and selective etching is performed. After forming the source electrode 405a and the drain electrode 405b by etching, a resist mask is Remove the smudge (see Figure 1(B)).

[0069] In the third photolithography process, ultraviolet light or KrF laser is used for exposure when forming the resist mask. The source electrodes adjacent to each other on the oxide semiconductor film 441 are preferably irradiated with laser light or ArF laser light. The width of the gap between the bottom end of the drain electrode and the bottom end of the transistor to be formed later is In addition, when performing exposure with a channel length L of less than 25 nm, the number n Extreme ultraviolet rays have extremely short wavelengths of 10 nm to several tens of nm. ) is used to perform exposure when forming a resist mask in the third photolithography process. Extreme ultraviolet light exposure provides high resolution and a large depth of focus. It is also possible to set the channel length L of the transistor to 10 nm or more and 1000 nm or less. The operating speed can be increased.

[0070] In order to reduce the number of photomasks and steps used in the photolithography process, The resist pattern is formed by a multi-tone mask, which is an exposure mask that allows the light to be projected at multiple intensities. The etching process may be performed using a resist mask formed using a multi-tone mask. The mask has a shape with multiple film thicknesses, and the shape can be further deformed by etching. This allows for multiple etching processes to be performed to create different patterns. Therefore, one multi-tone mask can handle at least two different patterns. Therefore, the number of exposure masks can be reduced. Since the corresponding photolithography process can also be eliminated, the process can be simplified.

[0071] Note that when the conductive film is etched, the oxide semiconductor film 441 is etched and divided. It is desirable to optimize the etching conditions so as not to cause this. It is difficult to obtain a condition in which the oxide semiconductor film 441 is not etched at all. During etching of the conductive film, the oxide semiconductor film 441 is only partially etched, and a groove is formed. In some cases, the oxide semiconductor film may have a recess (depression).

[0072] In this embodiment, a Ti film is used as the conductive film, and an In-Ga- Since a Zn-O-based oxide semiconductor was used, ammonia hydrogen peroxide (NH3H2O) was used as an etchant. A mixture of water and hydrogen peroxide is used.

[0073] Then, a plasma treatment is performed using a gas such as N2O, N2, or Ar to remove the exposed Water adsorbed on the surface of the oxide semiconductor film may be removed by the plasma treatment. In this case, the oxide semiconductor film 441 is partly covered with the oxide semiconductor film 441 without being exposed to air after the plasma treatment. It is preferable to form a contacting metal oxide film 407 .

[0074] Next, a layer of the oxide semiconductor film 4 A metal oxide film 407 is formed in contact with a part of the metal oxide film 407. The metal oxide film 407 is thicker than the oxide semiconductor film 441. The oxide semiconductor film on the channel side, that is, between the source electrode 405a and the drain electrode 405b It is a film that contacts with 441 and removes electric charges that accumulate at the interface.

[0075] The potential (charge) accumulated in the source electrode 405a or the drain electrode 405b A positive charge is transferred from the electrode 405a or the drain electrode 405b to the oxide semiconductor film, There is a possibility that the interface on the back channel side of the oxide semiconductor film is charged. The electrical conductivity of the oxide semiconductor film is different from the electrical conductivity of the material layer in contact with the back channel side of the oxide semiconductor film. When this happens, charges flow into the oxide semiconductor film, the charges are captured at the interface, and hydrogen in the oxide semiconductor film is released. This causes the transistor characteristics to fluctuate. Therefore, it is important to reduce hydrogen in the oxide semiconductor film and prevent charging. It is essential.

[0076] It is preferable that the difference in physical properties between the oxide semiconductor film and the metal oxide film is small. For example, the work function, the electron affinity, the dielectric constant, the band gap, etc. The difference between the band gap of the oxide semiconductor film and the band gap of the metal oxide film is less than 3 eV. For example, it is preferable to use an In-Ga-Zn-O-based oxide semiconductor as the oxide semiconductor film. When silicon oxide or aluminum oxide is used as the metal oxide film, the In-Ga-Zn The band gap of -O-based oxide semiconductors is 3.15 eV, and that of silicon oxide and aluminum oxide is The band gap of the nitrided silicon is 8 eV, which may cause the above problems. If a film containing a nitride (e.g., a silicon nitride film) is used instead of a metal oxide film, When the oxide semiconductor film is in contact with the oxide semiconductor film, the electrical conductivity of the oxide semiconductor film may change. There is a problem.

[0077] The metal oxide film 407 is quickly removed even if a positive charge is applied to the back channel side. However, the material used for the metal oxide film 407 has a hydrogen content of The amount of the oxide semiconductor film is equal to or less than that of the oxide semiconductor film. The energy gap of the material is not more than an order of magnitude larger than that of the material of the oxide semiconductor film. Preferably, the material has a viscosity of 1000 MPa or more.

[0078] In this way, by using the metal oxide film 407 for preventing charging, the oxide semiconductor Charge flows from a material layer in contact with the back channel side of the film 403 to the oxide semiconductor film 403. In addition, when the metal oxide film 407 is provided on the top surface of the oxide semiconductor film, As a result, the back channel side of the oxide semiconductor film 403 is assumed to be positively charged. In addition, by using the metal oxide film 407, the oxide It is possible to prevent the occurrence of a parasitic channel on the back channel side of the semiconductor film 403. This suppresses fluctuations in electrical characteristics, such as the electrical conductivity and threshold voltage, of the oxide semiconductor film 403. Therefore, the reliability of the transistor 410 can be improved.

[0079] In this embodiment, the metal oxide film 407 is formed by sputtering using a pulse direct current (DC) power source. The gallium oxide film obtained by the sputtering method is used as a target. In addition, it is preferable to use a gallium oxide target. In or Zn is added to the metal oxide film 407 to adjust the electrical conductivity. For example, a target of gallium oxide doped with indium or zinc may be used. A film containing 0.01 to 5 atomic percent of indium or zinc is formed by a sputtering method. By adding indium or zinc, the electrical conductivity of the metal oxide film 407 is improved. By making the electric conductivity of the oxide semiconductor film 402 closer to that of the oxide semiconductor film 403, the accumulation of charges can be further reduced. can be done.

[0080] The band gap of gallium oxide is 3.0 eV to 5.2 eV (e.g., 4.9 eV), The photoemission rate is 10-12, the electron affinity is 3.5 eV, and it is an In-Ga-Zn-O oxide semiconductor. Since the band gap is 3.15 eV, the dielectric constant is 15, and the electron affinity is 3.5 eV, The difference between the two is small, which is preferable. Gallium oxide also has a wide band of approximately 4.9 eV. Because it has a band gap, it is transparent in the visible light region. By using it as a metal oxide film, it is possible to obtain an In-Ga-Zn-O-based oxide semiconductor film and an oxide gas The contact resistance with the lithium film can be reduced. When gallium is used, in addition to In-Ga-Zn-O oxide semiconductors, oxide semiconductor materials and For example, an In-Ga-O based oxide semiconductor or a Ga-Zn-O based oxide semiconductor may be used.

[0081] In particular, when an In-Ga-Zn-O film is used as the oxide semiconductor film, the metal oxide film 40 Since it contains the gallium element common to GaOx used as 7, the materials are well compatible.

[0082] The metal oxide film 407 is preferably formed using a method that does not allow impurities such as water and hydrogen to be mixed in. When hydrogen is contained in the metal oxide film 407, the hydrogen may penetrate into the oxide semiconductor film or In the oxide semiconductor film, oxygen is extracted by hydrogen, and the back channel of the oxide semiconductor film is This may result in the resistance of the transistor becoming low (N-type), and a parasitic channel may be formed. The metal oxide film 407 is formed without using hydrogen in the film formation method so that the film contains as little hydrogen as possible. It is important that

[0083] In this embodiment, the metal oxide film 407 has a thickness of more than 10 nm and is made of an oxide semiconductor. A gallium oxide film having a thickness equal to or greater than that of the film 441 is formed by sputtering. By increasing the thickness of the metal oxide film 407, the metal oxide film 407 can efficiently release electric charges. The substrate temperature during film formation may be set to a temperature between room temperature and 300° C. The deposition of gallium oxide films by sputtering is carried out under a rare gas (typically argon) atmosphere. The reaction can be carried out in an oxygen atmosphere or in a mixed atmosphere of a rare gas and oxygen.

[0084] In the same manner as in the formation of the oxide semiconductor film, in order to remove residual moisture in the deposition chamber of the metal oxide film 407, For this purpose, it is preferable to use an adsorption type vacuum pump (such as a cryopump). The concentration of impurities contained in the metal oxide film 407 formed in the film formation chamber evacuated by a pump is reduced. In addition, the metal oxide film 407 can be formed in a deposition chamber by using the exhaust means for removing residual moisture. Alternatively, a turbo pump with a cold trap may be used.

[0085] The sputtering gas used in forming the metal oxide film 407 is hydrogen, water, a hydroxyl group, or It is preferable to use a high-purity gas from which impurities such as hydrides have been removed.

[0086] The metal oxide film 407 is formed on at least the channel forming region of the oxide semiconductor film, the source electrode 4 If necessary, the metal oxide film 407 may be selected to cover the gate electrode 405a and the drain electrode 405b. In addition, the etching of the gallium oxide film used in this embodiment may be performed in the following manner. Known wet etching or known dry etching can be used. For example, Then, wet etching is performed using a hydrofluoric acid solution or nitric acid solution.

[0087] Next, the oxide semiconductor film 441 and the metal oxide film 407 or the oxide semiconductor film 441 and the metal oxide film 407 are Oxygen 421 is introduced through the metal oxide film 407 into at least one of the interfaces with the metal oxide film 407. (See Figure 1(C)).

[0088] The oxygen 421 can be introduced by ion implantation or ion doping. In the ion implantation method, a source gas is turned into plasma, and the ions contained in the plasma are injected into the The ion species are extracted, mass separated, and the ion species having a predetermined mass are accelerated to form an ion beam. The ion doping method is a method in which a source gas is injected into the workpiece. The plasma is then generated, and ion species are extracted from the plasma by the action of a specific electric field. In this method, ion species are accelerated without being mass-separated and then injected into the workpiece as an ion beam. By introducing oxygen using ion implantation with volume separation, impurities such as metal elements are In addition, it is possible to prevent the ion doping from being added to the oxide semiconductor film. The ion beam irradiation area can be made larger in the ion beam irradiation method than in the ion implantation method. By adding oxygen using the ion doping method, the tact time can be shortened. can be done.

[0089] In order to introduce oxygen into the oxide semiconductor film 441 through the stacked metal oxide film 407, Therefore, the depth (region) of oxygen introduction can be controlled. The oxygen introduction depth can be controlled by adjusting the introduction conditions such as the acceleration voltage and the dose. In addition, the thickness of the metal oxide film 407 through which the light passes may be appropriately set and controlled.

[0090] Next, an insulating film 409 is formed on the metal oxide film 407 (see FIG. 1(D)). The insulating film 9 is made of an inorganic material such as a silicon oxide film, a silicon oxynitride film, or an aluminum oxide film. An oxide insulating film such as an aluminum oxide nitride film, an aluminum oxynitride film, or a silicon nitride film, A single layer or multilayer of a nitride insulating film such as an aluminum nitride film, an aluminum oxide nitride film, etc. For example, an oxide layer may be formed by sputtering from the metal oxide film 407 side. A silicon oxide film and a silicon nitride film are laminated.

[0091] The oxygen introduction process is carried out after the insulating film 409 is formed on the metal oxide film 407. is also good.

[0092] Next, the metal oxide film 407 and a part (a channel formation region) of the oxide semiconductor film 441 to which oxygen has been introduced are The heat treatment is performed with the two surfaces (regions) in contact with each other (see FIG. 1(E)).

[0093] The temperature of the heat treatment is 250° C. or higher and 650° C. or lower, preferably 450° C. or higher and 600° C. or lower. For example, the substrate is introduced into an electric furnace, which is one type of heat treatment device. Then, heat treatment is performed on the oxide semiconductor film at 450° C. for one hour in a nitrogen atmosphere.

[0094] The heat treatment device is not limited to an electric furnace, and may be a heat treatment device using heat conduction or heat from a heating element such as a resistance heating element. A device that heats the workpiece by radiation may be used. For example, a GRTA (Gas Reactor Transformer) apid Thermal Anneal) equipment, LRTA (Lamp Rapid T RTA (Rapid Thermal Anneal) equipment, etc. al) equipment can be used. The LRTA equipment can be a halogen lamp, a metal halide lamp, lamp, xenon arc lamp, carbon arc lamp, high pressure sodium lamp, high pressure mercury lamp This is a device that heats the workpiece by radiating light (electromagnetic waves) emitted from a lamp or other light source. The GRTA device is a device that uses high-temperature gas to perform heat treatment. Inert gases such as argon or nitrogen that do not react with the workpiece during heat treatment In addition, when a GRTA device is used as the heat treatment device, Because the heat treatment time is short, the substrate is heated in an inert gas atmosphere at a high temperature of 650℃ to 700℃. You may do so.

[0095] Heat treatment is carried out in a vacuum of nitrogen, oxygen, or ultra-dry air (water content of 20 ppm or less, preferably 1 ppm). m or less, preferably 10 ppb or less air), or rare gases (argon, helium, etc.) However, the above-mentioned nitrogen, oxygen, ultra-dry air, rare gas, or other atmosphere may be used. It is preferable that the gas does not contain nitrogen, oxygen, or hydrogen. The purity of the rare gas should be 6N (99.9999%) or more, preferably 7N (99.9999%) or more. 9%) or more (i.e., impurity concentration should be 1 ppm or less, preferably 0.1 ppm or less). is preferred.

[0096] In this manner, the oxide semiconductor film 441, the metal oxide film 407, or the oxide semiconductor film 441 and the metal Oxygen is added to at least one of the interfaces with the metal oxide film 407, and then a heat treatment is performed. As a result, the oxide semiconductor film 441, the metal oxide film 407, or the oxide semiconductor film 441 and It is possible to terminate the dangling bonds present at the interface with the metal oxide film 407 with oxygen. In the oxide semiconductor film 441, in the metal oxide film 407, or in the oxide semiconductor film 441 and the metal oxide film If there is a dangling bond at the interface with 407, hydrogen may diffuse and form a bond. However, by terminating the dangling bonds with oxygen, the formation of bonds can be prevented. It is.

[0097] In addition, the introduction of oxygen can reduce the bond between the metal and hydrogen that constitutes the oxide semiconductor, or the The bonds between the metal and the hydroxyl groups are broken, and these hydrogen or hydroxyl groups react with oxygen. Water is produced by heating the water. Therefore, impurities such as hydrogen and hydroxyl groups are removed by heating. can be easily desorbed as water.

[0098] Thus, the introduction of oxygen and the heat treatment prevent the formation of bonds and also reduce the oxide The semiconductor film can be dehydrated or dehydrogenated, and hydrogen, moisture, and water can be removed from the oxide semiconductor film. Impurities such as acid groups or hydrides can be excluded.

[0099] In addition, heat treatment was performed while the oxide semiconductor film was in contact with the metal oxide film 407 containing oxygen. Therefore, the main component material that constitutes the oxide semiconductor is reduced at the same time as the impurity removal process. Oxygen, which is one of the oxygen-containing metal oxide films, is supplied to the oxide semiconductor film from the metal oxide film 407. This makes it possible to reduce the number of charge trapping centers in the oxide semiconductor film. In the above process, the oxide semiconductor film 403 is highly purified and electrically i-type (intrinsic). By this heat treatment, impurities are simultaneously removed from the metal oxide film 407, and the metal oxide film 407 is highly purified. do.

[0100] In the highly purified oxide semiconductor film 403, there are very few carriers derived from donors ( (close to zero), and the carrier concentration is 1×10 14 / cm 3 Less than 1 x 10 12 / c m 3 less than 1×10 11 / cm 3 is less than.

[0101] In addition, oxygen is added by passing through the metal oxide film 407, so that the oxide semiconductor film 44 The atomic arrangement near the interface between 1 and the metal oxide film 407 is distorted, and the subsequent heat treatment At this time, rearrangement of atoms occurs in the vicinity of the interface between the oxide semiconductor film 403 and the metal oxide film 407. At this time, atomic bonds are generated between the oxide semiconductor film 403 and the metal oxide film 407. Therefore, the difference in physical properties, such as electrical conductivity, between the oxide semiconductor film 403 and the metal oxide film 407 is reduced. This can suppress charging at the interface on the back channel side of the oxide semiconductor film. Therefore, fluctuations in electrical characteristics such as the threshold voltage of the oxide semiconductor film can be suppressed. Therefore, the reliability of the transistor can be improved.

[0102] Through the above steps, the transistor 410 is formed (see FIG. 1E). 0 is an oxide semiconductor that contains impurities such as hydrogen, moisture, hydroxyl groups, and hydrides (also called hydrogen compounds). A transistor including a highly purified oxide semiconductor film 403 that is intentionally removed from a conductive film. Therefore, the transistor 410 has suppressed fluctuations in electrical characteristics and is electrically stable. It is.

[0103] Note that the heat treatment after the introduction of oxygen may be performed before the insulating film 409 is formed. After the heat treatment, an insulating film 409 is formed on the metal oxide film 407 .

[0104] In addition to the above heat treatment, other heat treatment may be performed. After forming 41, a heat treatment (first heat treatment) was performed to form a metal oxide film 407. A further heat treatment (second heat treatment) may be performed later. In this case, the first heat treatment For example, heating is performed in an inert gas atmosphere, and then heating is performed in an oxygen atmosphere (an atmosphere containing at least oxygen). The first heat treatment can be a cooling treatment under atmospheric pressure. In this manner, the oxide semiconductor film can be suitably dehydrated and oxidized.

[0105] After the step of FIG. 1(E), a heat treatment may be further performed. For example, the heat treatment may be performed in air for 10 Heat treatment may be performed at 0° C. or higher and 200° C. or lower for 1 hour or longer and 30 hours or shorter. The treatment may be performed by maintaining a constant heating temperature or by heating from room temperature to 100°C or higher and 200°C or higher. The heating to the heating temperature below and the cooling from the heating temperature to room temperature may be repeated several times. stomach.

[0106] In addition, the transistor 410 including the oxide semiconductor film 403 has a relatively high field-effect mobility. Therefore, the use of the above transistor in the pixel portion enables high-speed driving. In addition, a highly purified oxide semiconductor film can be used to provide a high-quality image. Since a driver circuit portion having a transistor including a MOS transistor and a pixel portion can be formed on the same substrate, a semiconductor device can be The number of parts can be reduced.

[0107] In the transistor 410 including the metal oxide film 407, In addition, the generation of a parasitic channel on the side of the transistor 41 can be prevented. In the case of FIG. 1, a parasitic channel on the back channel side of the oxide semiconductor film 403 is prevented from being generated. This suppresses the fluctuation of the threshold voltage, resulting in a more reliable transistor. It can be said that:

[0108] Incidentally, in the transistor 410 illustrated in FIG. 1E, the oxide semiconductor film 403 and The metal oxide film 407 is provided in contact with the two dielectric layers. In this case, the dielectric constant of the first layer (the oxide semiconductor film 403 in the transistor 410) is The thickness of the second layer (metal in the transistor 410) is d1, the electrical conductivity is σ1, and the thickness is d1. When the dielectric constant of the oxide film 407) is ε2, the electrical conductivity is σ2, and the thickness is d2, the stack of two layers is can be expressed by the model diagram in Fig. 9(A). In Fig. 9(A), S represents the area. In addition, the model diagram in Figure 9(A) can be replaced with the equivalent circuit in Figure 9(B). In the figure, C1 is the capacitance value of the first layer, G1 is the resistance value of the first layer, C2 is the capacitance value of the second layer, and G 2 represents the resistance value of the second layer. Here, when a voltage V is applied to the second layer, 2 It is assumed that an electric charge Q, expressed by the following equation (1), accumulates at the interface of the layers.

[0109]

number

[0110] In the transistor 410 shown in FIG. 1E, the interface where the charge Q is stored is an oxidized The dielectric constant or electrical conductivity of the metal oxide film 407 corresponds to the back channel side of the semiconductor film 403. By appropriately setting the conductivity or the film thickness of the metal oxide film 407, the interface on the back channel side The charge Q accumulated in the

[0111] Here, by modifying formula (1), the following formulas (2) and (3) are obtained.

[0112]

number

[0113] From equations (2) and (3), in order to reduce the charge Q, the following four conditions (A) to (D) are required. The following cases can be envisaged. Condition (A) τ i Make it very large. Condition (B) Make V2 approach zero, that is, make G2 much larger than G1. Condition (C) Make C2 approach zero. Condition (D) Make τ1 closer to τ2.

[0114] Under condition (A), τ i To make τ very large, i =(C1+C2) / (G1+G2) Therefore, we should make (C1+C2) much larger than (G1+G2). C1 and G1 are Since the charge Q is a parameter of the oxide semiconductor film 403, the charge Q is reduced by the metal oxide film 407. To reduce this, it is necessary to increase C2. However, since C2 = ε2S / d2, If C2 is increased at ε2, Q will become larger according to equation (2), which creates a contradiction.i It is not possible to adjust the charge Q.

[0115] In order to make V2 approach zero under condition (B), G2>>G1 must be satisfied according to equation (3). Since G1 is a parameter of the oxide semiconductor film 403, the metal oxide film 407 In order to reduce the charge Q, it is necessary to increase G2. Specifically, G2 = σ2S / d2, so we must either reduce d2 or select a material with a large σ2. However, the reduction of d2 makes C2 larger than C2=ε2S / d2, and Q becomes the same as in condition (A). In addition, the metal oxide film 407 has a large σ2. This means that the electrical conductivity is higher than that of the oxide semiconductor film 403, and the occurrence of leakage current and shunt current is prevented. This cannot be adopted due to the high risk of short circuit.

[0116] In order to make C2 very small under condition (C), d2 must be made large, since C2=ε2S / d2. This means either reducing the capacitance or selecting a material with a small ε2.

[0117] In addition, under condition (D), in order to make τ1 closer to τ2, τ1=ε1 / σ1, τ2=ε2 / Since σ2, we should choose a membrane where ε1 / σ1 ≒ ε2 / σ2. This means that C1 / G1 ≒ C Equivalent to 2 / G2.

[0118] Therefore, in order to effectively prevent the accumulation of the charge Q, the thickness (d2 ) is increased, or a material with a small dielectric constant (ε2) is used as the material for the metal oxide film 407. Preferably, the material is smaller than the oxide semiconductor film 403 (for example, the dielectric constant ε is 8 or more and 20 or less). Alternatively, ε1 / σ1 ≒ ε2 / σ2 (ε1 is an oxide semiconductor material) should be selected. The physical properties of the oxide semiconductor film are close to those of the oxide semiconductor film so that the dielectric constant of the oxide semiconductor film is σ1, and the conductivity of the oxide semiconductor film is σ2. It is preferable to select a material having a low resistance as the metal oxide film.

[0119] As described above, a semiconductor device using an oxide semiconductor and having stable electrical characteristics is provided. Therefore, a highly reliable semiconductor device can be provided.

[0120] As described above, the configurations, methods, etc. described in this embodiment may be used in conjunction with the configurations, methods, etc. described in other embodiments. They can be used in any suitable combination.

[0121] (Embodiment 2) In this embodiment mode, another embodiment of a method for manufacturing a semiconductor device will be described. A part or a part having a similar function and a process can be performed in the same manner as in the above embodiment. In addition, detailed explanations of the same parts will be omitted.

[0122] In this embodiment, the method for manufacturing the transistor 410 described in Embodiment 1 is different from the method for manufacturing the transistor 410 described in Embodiment 1. An example in which heat treatment is performed on an oxide semiconductor film before forming a metal oxide film 407 in contact with the oxide semiconductor film. Shows.

[0123] This heat treatment is performed after the oxide semiconductor film is formed and before the metal oxide film 407 is formed. If the source electrode 4 is formed on the oxide semiconductor film, the source electrode 4 may be formed on the oxide semiconductor film before processing. This may be applied either before or after the formation of the SiO 2 film and drain electrode 405a and drain electrode 405b.

[0124] The temperature of the heat treatment is 250°C or higher and 650°C or lower, preferably 450°C or higher and 600°C or lower. For example, the substrate is placed in an electric furnace, which is a type of heat treatment apparatus, and the oxide semiconductor film is heated. Heat treatment is then performed for 1 hour at 450°C in a nitrogen atmosphere. After the heat treatment, do not expose the material to air. It is preferable to form a metal oxide film without using the oxide semiconductor film, and to prevent water or hydrogen from re-mixing into the oxide semiconductor film. stomach.

[0125] The heat treatment device is not limited to an electric furnace, and may be a heat treatment device using heat conduction or heat from a heating element such as a resistance heating element. A device that heats the workpiece by radiation may be used. For example, a GRTA device or an LRT device may be used. A RTA device or other RTA equipment can be used. When using this method, the heat treatment time is short, so the inactivation is performed by heating to a high temperature of 650℃ to 700℃. The substrate may be heated in a reactive gas.

[0126] Heat treatment is carried out in a vacuum of nitrogen, oxygen, or ultra-dry air (water content of 20 ppm or less, preferably 1 ppm). m or less, preferably 10 ppb or less air), or rare gases (argon, helium, etc.) However, the above-mentioned nitrogen, oxygen, ultra-dry air, rare gas, or other atmosphere may be used. It is preferable that the gas does not contain nitrogen, oxygen, or hydrogen. The purity of the rare gas should be 6N (99.9999%) or more, preferably 7N (99.99999%). %) or more (i.e., the impurity concentration is 1 ppm or less, preferably 0.1 ppm or less). preferable.

[0127] By this heat treatment, impurities such as moisture or hydrogen in the oxide semiconductor film are reduced. It is possible.

[0128] Furthermore, a metal oxide film is formed on the oxide semiconductor film, and the metal oxide film is passed through the metal oxide film, which is an oxide insulating layer. In addition, by introducing oxygen into the oxide semiconductor film, the metal and hydrogen constituting the oxide semiconductor are or between the metal and the hydroxyl group, and The acid group reacts with oxygen to produce water. After the introduction of oxygen, an insulating layer is formed. By subjecting the material to heat treatment, impurities such as hydrogen or hydroxyl groups that had remained strongly are converted into water. This can facilitate the detachment.

[0129] Since heat treatment is performed in a state where the oxide semiconductor film and the metal oxide film containing oxygen are in contact with each other, It is one of the main components of oxide semiconductors that is reduced at the same time as the removal process. Oxygen can be supplied to the oxide semiconductor film from the metal oxide film containing oxygen.

[0130] Therefore, the oxide semiconductor film is subjected to heat treatment before the formation of the metal oxide film and after the formation of the metal oxide film. If heat treatment is performed after oxygen is introduced, impurities such as moisture and hydrogen are further removed. An i-type (intrinsic semiconductor) or an oxide semiconductor film that is extremely close to i-type can be obtained.

[0131] Therefore, in a transistor including a highly purified oxide semiconductor film, fluctuation in electrical characteristics is suppressed. It is electrically stable.

[0132] In addition, a transistor having a metal oxide film for preventing charging is It is possible to prevent the occurrence of a parasitic channel on the side of the transistor. By preventing the generation of a parasitic channel on the back channel side of the oxide semiconductor film, This makes it possible to suppress fluctuations in the value voltage.

[0133] As described above, a semiconductor device using an oxide semiconductor and having stable electrical characteristics is provided. Therefore, a highly reliable semiconductor device can be provided.

[0134] As described above, the configurations, methods, etc. described in this embodiment may be used in conjunction with the configurations, methods, etc. described in other embodiments. They can be used in any suitable combination.

[0135] (Embodiment 3) A display function is provided using the transistor exemplified in either embodiment 1 or 2. A semiconductor device (also called a display device) can be manufactured. A part or the whole of the operating circuit is formed on the same substrate as the pixel section to form a system on panel. It can be achieved.

[0136] In FIG. 2A, a pixel portion 4002 provided on a first substrate 4001 is surrounded by a A sealant 4005 is provided on the first substrate 4002, and the first substrate 4002 is sealed with a second substrate 4006. In A), a region surrounded by a sealant 4005 on a first substrate 4001 and The semiconductor layer is formed of a single crystal semiconductor film or a polycrystalline semiconductor film on a separately prepared substrate in a different region. A scanning line driver circuit 4004 and a signal line driver circuit 4003 are also mounted. A signal line driver circuit 4003 and a scanning line driver circuit 4004 or a signal line driver circuit 4005 are provided to the pixel portion 4002. Various signals and potentials are transmitted through the FPC (Flexible Printed Circuit). )Powered by 4018a and 4018b.

[0137] In FIG. 2B and FIG. 2C, a pixel portion 4002 is provided on a first substrate 4001, and a scanning A sealant 4005 is provided so as to surround the line driver circuit 4004. A second substrate 4006 is provided on the substrate 4002 and the scanning line driver circuit 4004. The pixel portion 4002 and the scanning line driver circuit 4004 are formed by a first substrate 4001 and a sealant 4002. The display element is sealed by the second substrate 4005 and the second substrate 4006. In C), the area surrounded by the sealant 4005 on the first substrate 4001 and The semiconductor layer is formed of a single crystal semiconductor film or a polycrystalline semiconductor film on a separately prepared substrate in a different region. In FIG. 2B and FIG. 2C, a signal line driver circuit 4003 is mounted. A signal line driver circuit 4003 and a scanning line driver circuit 4004 or a signal line driver circuit 4005 are provided to the pixel portion 4002. The various signals and potentials are supplied from the FPC4018.

[0138] In addition, in FIG. 2B and FIG. 2C, a signal line driver circuit 4003 is formed separately, and the first substrate 4 001, but the present invention is not limited to this configuration. Alternatively, only a part of the signal line driver circuit or a part of the scanning line driver circuit may be formed and mounted. It may be formed separately and mounted.

[0139] The method of connecting the separately formed drive circuit is not particularly limited, and may be any of the following: ip On Glass) method, wire bonding method, or TAB (Tape A The C utomated Bonding method can be used. This is an example in which a signal line driver circuit 4003 and a scanning line driver circuit 4004 are implemented by the OG method. FIG. 2B shows an example in which a signal line driver circuit 4003 is mounted by the COG method, and FIG. 4003) is an example in which a signal line driver circuit 4003 is mounted by the TAB method.

[0140] The display device includes a panel in which a display element is sealed, and a controller for the panel. and modules in which ICs, etc., including the above, are mounted.

[0141] In this specification, the term "display device" refers to an image display device, a display device, or an optical Also refers to connectors, such as FPC or TAB tape. or a module with TCP attached, a printed wiring board on the tip of TAB tape or TCP A module with a display element or a display device with an IC (integrated circuit) directly mounted on it using the COG method. The display device includes all installed modules.

[0142] The pixel portion and the scanning line driver circuit provided on the first substrate have a plurality of transistors. The transistor illustrated in either the first or second embodiment can be used. Cut.

[0143] Examples of display elements provided in the display device include liquid crystal elements (also called liquid crystal display elements), light-emitting elements ( The light-emitting element can be used as a light-emitting display element. This category includes elements whose brightness can be controlled, specifically inorganic EL (Electroluminescent) Luminescence, organic electroluminescence, etc. Also, electronic ink, etc. A display medium whose contrast changes depending on use can also be applied.

[0144] One embodiment of a semiconductor device will be described with reference to FIGS. 3 to 5. FIGS. 3 to 5 show the same structure as FIG. B) corresponds to the cross-sectional view at MN.

[0145] As shown in FIG. 3 to FIG. 5, the semiconductor device has a connection terminal electrode 4015 and a terminal electrode 4016. The connection terminal electrode 4015 and the terminal electrode 4016 are terminals of the FPC 4018. and electrically connected via an anisotropic conductive film 4019 .

[0146] The connection terminal electrode 4015 is formed from the same conductive film as the first electrode layer 4030. 016 is a conductive film that is the same as the source and drain electrodes of the transistors 4010 and 4011. It is formed by:

[0147] A pixel portion 4002 and a scanning line driver circuit 4004 are provided on a first substrate 4001. 3 to 5, the transistors included in the pixel portion 4002 are 4004 and a transistor 4011 included in the scanning line driver circuit 4004. In FIG. 3, the transistors 4010 and 4011 are covered with a metal oxide film to prevent charging. 4 and 5, an insulating layer 4021 is further provided. Note that the insulating film 4023 functions as a base film.

[0148] In this embodiment, the transistors 4010 and 4011 are the transistors The transistor shown in either of the above can be applied.

[0149] In the transistors 4010 and 4011, an oxide semiconductor film is stacked Oxygen is introduced through the metal oxide film 4020, and the insulating film 40 is formed on the metal oxide film 4020. After forming 24, a heat treatment is performed to remove hydrogen, moisture, hydroxyl groups, or hydrides (water Impurities such as fluorine-containing compounds are intentionally removed from the oxide semiconductor film to obtain a highly purified oxide semiconductor film. The oxide semiconductor film is a thin film. The introduction of oxygen causes a gap between the metal and hydrogen that constitutes the oxide semiconductor. or the bond between the metal and the hydroxyl group, and The group reacts with oxygen to produce water, so the subsequent heat treatment removes impurities. Certain hydrogen or hydroxyl groups can be made easier to eliminate as water.

[0150] In order to introduce oxygen into the oxide semiconductor film through the stacked metal oxide film 4020, The oxygen introduction depth (introduction region) can be controlled, and oxygen can be efficiently introduced into the oxide semiconductor film. It can be easily introduced.

[0151] Further, heat treatment is performed in a state where the oxide semiconductor film and the metal oxide film 4020 containing oxygen are in contact with each other. Therefore, the main component material of the oxide semiconductor, which is reduced at the same time as the impurity removal process, Oxygen, which is one of the materials, is supplied to the oxide semiconductor film from the metal oxide film 4020 containing oxygen. As a result, the oxide semiconductor film becomes more highly purified and electrically i-type (intrinsic).

[0152] Therefore, the transistor 4010 and the transistor 4020 each include a highly purified oxide semiconductor film. 011 is electrically stable with the electrical characteristic fluctuation suppressed. As the semiconductor device of this embodiment shown in FIG. 5, a highly reliable semiconductor device can be provided. do.

[0153] In addition, a transistor having a metal oxide film for preventing charging is It is possible to prevent the occurrence of a parasitic channel on the side of the transistor. By preventing the generation of a parasitic channel on the back channel side of the oxide semiconductor film, This makes it possible to suppress fluctuations in the value voltage.

[0154] In this embodiment mode, the transistor 4011 for the driver circuit is formed over the insulating film 4024. A conductive layer is provided in a portion overlapping with a channel formation region of the oxide semiconductor film. By providing the oxide semiconductor film in a position overlapping with a channel formation region, In this case, the amount of change in the threshold voltage of the transistor 4011 can be further reduced. The conductive layer may have the same potential as the gate electrode of the transistor 4011 or may have a different potential. The potential of the conductive layer may be G It may be ND, 0V, or floating.

[0155] The conductive layer also shields the external electric field, i.e., the external electric field is prevented from penetrating the internal (thin film transistor) It also has a function to prevent the circuit part (including the circuit part) from being affected (especially the electrostatic shielding function against static electricity). The shielding function of the conductive layer prevents the electrical conductivity of the transistor from being affected by external electric fields such as static electricity. Therefore, it is possible to prevent the general characteristics from fluctuating.

[0156] The transistor 4010 provided in the pixel portion 4002 is electrically connected to a display element. The display element is not particularly limited as long as it can display an image. can be used.

[0157] FIG. 3 shows an example of a liquid crystal display device using a liquid crystal element as a display element. The liquid crystal element 4013 is a first electrode layer 4030, a second electrode layer 4031, and a liquid crystal layer. The liquid crystal layer 4008 is sandwiched between insulating films functioning as alignment films. The second electrode layer 4031 is provided on the second substrate 4006 side. The first electrode layer 4030 and the second electrode layer 4031 are stacked with a liquid crystal layer 4008 interposed therebetween. It has a layered structure.

[0158] Also, 4035 is a columnar spacer obtained by selectively etching the insulating film. It is provided to control the thickness (cell gap) of the liquid crystal layer 4008. A pacer may be used.

[0159] When liquid crystal elements are used as display elements, thermotropic liquid crystal, low molecular weight liquid crystal, high molecular weight liquid crystal, etc. For example, a liquid crystal, a polymer-dispersed liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, etc. can be used. Depending on the conditions, the liquid crystal material can have a cholesteric phase, a smectic phase, a cubic phase, or a chiral phase. It shows nematic phase, isotropic phase, etc.

[0160] Alternatively, a liquid crystal that exhibits a blue phase without using an alignment film may be used. The blue phase is one of the liquid crystal phases. When the temperature of cholesteric liquid crystal is increased, the phase immediately transitions from the cholesteric phase to the isotropic phase. The blue phase appears only in a narrow temperature range, so it is necessary to improve the temperature range. In order to achieve this, a liquid crystal composition containing 5% by weight or more of a chiral agent is used in the liquid crystal layer. The liquid crystal composition containing the liquid crystal exhibiting the blue phase and the chiral agent has a short response speed of 1 msec or less. Since the liquid crystal display is optically isotropic, no alignment treatment is required and the viewing angle dependency is small. Since there is no need to provide a rubbing treatment, the It is possible to prevent electrostatic damage, which may occur during the manufacturing process, and to reduce defects and damage to liquid crystal display devices. Therefore, it is possible to improve the productivity of the liquid crystal display device. The electrical characteristics of transistors using conductive films are significantly affected by static electricity. Therefore, the characteristics of a transistor using an oxide semiconductor film may vary significantly and deviate from the design range. It is more effective to use a blue phase liquid crystal material in a liquid crystal display device having the above-mentioned structure.

[0161] The specific resistivity of the liquid crystal material is 1×10 9 Ω cm or more, preferably 1×10 1 1 Ω cm or more, and more preferably 1×10 12 Ω·cm or more. The specific resistivity values ​​in the specification are those measured at 20°C.

[0162] The size of the storage capacitor provided in the liquid crystal display device is determined by the lead of the transistor arranged in the pixel portion. It is set so that the charge can be held for a predetermined period of time, taking into consideration the current drain and other factors. By using a transistor having a semiconductor film, the liquid crystal capacitance of each pixel is It is sufficient to provide a storage volume having a size of 1 / 3 or less, preferably 1 / 5 or less, of the capacity of the do.

[0163] The transistor including the purified oxide semiconductor film used in this embodiment is in an off state. Therefore, the current value (off-state current value) at the time of the image signal or other electric signals can be reduced. The retention time of the data can be extended, and the write interval can also be set longer when the power is on. This reduces the frequency of refresh operations, resulting in reduced power consumption. It plays a major role.

[0164] In addition, the transistor including the purified oxide semiconductor film used in this embodiment has a relatively Since a relatively high field effect mobility can be obtained, high speed driving is possible. By using the above transistor in the pixel portion, a high-quality image can be provided. In addition, a driver circuit portion having the above transistor and a pixel portion can be formed over the same substrate. Therefore, the number of parts in the liquid crystal display device can be reduced.

[0165] There are two types of LCD displays: TN (Twisted Nematic) and IPS (In-P lane-Switching) mode, FFS (Fringe Field Switching) mode ching) mode, ASM(Axially Symmetric aligned) Micro-cell mode, OCB (Optical Compensated B) irefringence mode, FLC (Ferroelectric Liqui d Crystal) mode, AFLC (AntiFerroelectric Liq. uid Crystal) mode can be used.

[0166] In addition, normally black type liquid crystal display devices, such as those using a vertical alignment (VA) mode, The liquid crystal display device may be a transmission type liquid crystal display device. This is a method of controlling the arrangement of crystal molecules, and it applies a In this method, the liquid crystal molecules are aligned vertically. There are several types of vertical alignment modes: For example, MVA (Multi-Domain Vertical Alignment) nt) mode, PVA (Patterned Vertical Alignment) You can also use the ASV mode, ASV mode, etc. It is a multi-layered device that is divided into regions (sub-pixels) and designed to tilt the molecules in different directions in each region. A method known as domaining or multi-domain design can be used.

[0167] In addition, in display devices, they are used as black matrices (light-shielding layers), polarizing members, phase difference members, reflectors, etc. Optical members (optical substrates) such as a prevention member are provided as appropriate. For example, a polarizing substrate and a retardation substrate Alternatively, a backlight or a sidelight may be used as the light source. It's fine.

[0168] In addition, multiple light-emitting diodes (LEDs) are used as backlights to display the image in a time-division format. It is also possible to perform a field sequential drive method. By applying the color driving method, it is possible to display colors without using color filters. This can be done.

[0169] The display method in the pixel section uses the progressive method, interlace method, etc. In addition, the color elements controlled by pixels when displaying colors are RGB (R is The color is not limited to the three colors red, green, and blue. For example, RGBW (W stands for white). , or RGB plus one or more colors such as yellow, cyan, magenta, etc. The size of the display area may be different for each dot of the color element. The present invention is not limited to color display devices, but is applicable to monochrome display devices. It is also possible.

[0170] In addition, a light-emitting element that utilizes electroluminescence is used as a display element included in the display device. The light-emitting element utilizing electroluminescence is made of a light-emitting material They are classified according to whether they are organic or inorganic compounds. Generally, the former are called organic E The latter is called an inorganic EL element.

[0171] In an organic EL element, electrons and holes are released from a pair of electrodes by applying a voltage to the light-emitting element. are injected into layers containing light-emitting organic compounds, causing a current to flow. The rears (electrons and holes) recombine to form an excited state in the light-emitting organic compound. When the excited state returns to the ground state, light is emitted. Such a light-emitting element is called a current-excitation type light-emitting element.

[0172] Inorganic EL elements are divided into dispersion-type inorganic EL elements and thin-film-type inorganic EL elements according to their element structure. Dispersion-type inorganic EL elements have a light-emitting layer in which particles of a light-emitting material are dispersed in a binder. The emission mechanism is a donor-acceptor reaction that utilizes the donor and acceptor levels. Thin-film inorganic EL elements are made by sandwiching a light-emitting layer between dielectric layers. The structure is sandwiched between electrodes, and the light emission mechanism utilizes the inner shell electron transition of metal ions. In this example, the light-emitting element is an organic EL element. do.

[0173] In order to extract light emitted from the light-emitting element, at least one of the pair of electrodes must be transparent. Then, a transistor and a light emitting element are formed on the substrate, and light is emitted from the opposite side of the substrate. Top emission, bottom emission where the light is emitted from the surface on the substrate side, or the surface on the substrate side and the opposite side There are light-emitting elements with a double-sided emission structure that extracts light from the outside, and light-emitting elements with any emission structure can be used. It is possible.

[0174] FIG. 4 shows an example of a light-emitting device using a light-emitting element as a display element. A transistor 513 is electrically connected to a transistor 4010 provided in the pixel portion 4002 . The light-emitting element 4513 includes a first electrode layer 4030, an electroluminescent layer 4511, a second electrode layer 4032, and a light-emitting layer 4513. The electrode layer 4031 has a laminated structure, but is not limited to the structure shown. The configuration of the light emitting element 4513 can be changed as appropriate according to the direction of emitted light.

[0175] The partition 4510 is formed using an organic insulating material or an inorganic insulating material, particularly a photosensitive resin. An opening is formed on the first electrode layer 4030 using a material, and the sidewall of the opening is a continuous curved It is preferable to form the inclined surface so that the inclined surface is formed with a certain rate.

[0176] The electroluminescent layer 4511 may be composed of a single layer or may be composed of a plurality of layers stacked together. It doesn't matter whether it is done or not.

[0177] In order to prevent oxygen, hydrogen, moisture, carbon dioxide, and the like from entering the light-emitting element 4513, the second electrode layer A protective film may be formed on the insulating film 4031 and the partition wall 4510. The protective film may be made of silicon nitride. A silicon nitride oxide film, a DLC film, etc. can be formed on the first substrate 400. The space sealed by the first substrate 4001, the second substrate 4006, and the sealant 4005 is filled with a filler 45. 14 is provided and sealed. In this way, it is highly airtight and degassing is possible to prevent exposure to the outside air. Protective films with low damage (laminated films, UV-cured resin films, etc.) and covering materials It is preferable to package (enclose) the

[0178] Filler 4514 can be inert gas such as nitrogen or argon, or ultraviolet curing resin or Thermosetting resin can be used, and PVC (polyvinyl chloride), acrylic, polyimide, etc. Mido, epoxy resin, silicone resin, PVB (Polyvinyl Butyral) or EVA (Elastomer) For example, nitrogen may be used as a filler. stomach.

[0179] If necessary, a polarizing plate or a circular polarizing plate (including an elliptical polarizing plate) may be provided on the light-emitting surface of the light-emitting element. Optical films such as retardation plates (λ / 4 plates, λ / 2 plates) and color filters may be provided as appropriate. In addition, the polarizing plate or the circular polarizing plate may be provided with an anti-reflection film. Anti-glare treatment can be applied to diffuse reflected light and reduce glare.

[0180] It is also possible to provide electronic paper that drives electronic ink as a display device. Electronic paper is also called an electrophoretic display (electrophoretic display) and is a paper-based display. It is possible to make a display that is as easy to read as a regular display, consumes less power than other displays, and is thinner and lighter in size. This has the advantage that

[0181] The electrophoretic display device may have various forms, but it has a first particle having a positive charge and A microcapsule containing a negatively charged second particle and a negatively charged second particle is introduced into a solvent or solute. By applying an electric field to the microcapsules, The particles in the cell are moved in opposite directions to each other, and only the color of the particles that have gathered on one side is displayed. In addition, the first particles or the second particles contain a dye, and they do not migrate in the absence of an electric field. The color of the first particle and the color of the second particle are different (including colorless). )

[0182] In this way, the electrophoretic display device is a so-called This is a display that utilizes the dielectrophoretic effect.

[0183] The microcapsules dispersed in a solvent are called electronic ink. The electronic ink can be printed on surfaces such as glass, plastic, fabric, and paper. A color display is also possible by using a color filter or particles having a pigment.

[0184] The first particles and the second particles in the microcapsules are made of a conductive material, an insulating material, Semiconductor materials, magnetic materials, liquid crystal materials, ferroelectric materials, electroluminescent materials, A material selected from the group consisting of magnetochromic material, magnetophoretic material, and a composite material thereof. Just use it.

[0185] In addition, display devices using the twist ball display method can also be used as electronic paper. The twist ball display method uses black and white spherical particles as the display element. The insulating layer is disposed between a first electrode layer and a second electrode layer, and the first electrode layer and the second electrode layer are electrically connected to each other. This is a method of displaying information by controlling the orientation of spherical particles by generating a potential difference between the electrode layers. do.

[0186] FIG. 5 shows an active matrix electronic paper as one mode of a semiconductor device. The electronic paper is an example of a display device that uses the twisting ball display method.

[0187] A first electrode layer 4030 connected to the transistor 4010 and a second electrode layer 4006 Between the second electrode layer 4031 and the black area 4615a and the white area 4615b, A spherical particle 4613 is provided that includes a cavity 4612 that is filled with liquid around it. The spherical particles 4613 are filled with a filler 4614 such as a resin. The second electrode layer 4031 corresponds to a common electrode (opposite electrode). are electrically connected.

[0188] In addition, in FIG. 3 to FIG. 5, the first substrate 4001 and the second substrate 4006 are made of glass. In addition to a glass substrate, a flexible substrate can also be used. For example, a light-transmitting plastic substrate can be used. As for plastic, FRP (Fibreglass) is used. s-Reinforced Plastics) plate, PVF (Polyvinyl fluoride) A film, a polyester film or an acrylic resin film can be used. Also, a sheet with a structure in which aluminum foil is sandwiched between PVF film or polyester film. can also be used.

[0189] The insulating film 4024 functions as a protective film for the transistor.

[0190] In addition, the metal oxide film 4020 prevents the occurrence of a parasitic channel on the back channel side of the oxide semiconductor film. This not only prevents the formation of impurities, but also eliminates impurities such as hydrogen, moisture, hydroxyl groups, and hydrides. At the same time, the oxygen supply to the oxide semiconductor film is also effective to reduce oxygen that is lost from the oxide semiconductor film. do.

[0191] The metal oxide film 4020 is a gallium oxide film formed by sputtering. Also, a film of gallium oxide with indium or zinc added thereto may be used. A gallium oxide film containing 0.01 to 5 atomic percent of indium or zinc can be used. The electrical conductivity of the metal oxide film 4020 is improved by adding indium or zinc. Therefore, the accumulation of electric charges can be further reduced.

[0192] The insulating film 4024 is formed by sputtering a silicon nitride film, a silicon nitride oxide film, Aluminum oxide film, aluminum nitride film, aluminum oxynitride film, or aluminum nitride oxide film The insulating film may be formed of a single layer or a multilayer of aluminum films.

[0193] The insulating layer 4021 can be formed using an inorganic insulating material or an organic insulating material. In addition, acrylic resin, polyimide, benzocyclobutene resin, polyamide, epoxy resin Heat-resistant organic insulating materials such as grease are suitable for use as a planarizing insulating film. In addition to the above organic insulating materials, low-k materials, siloxane resins, and PSG (phosphorus glass), BPSG (boron phosphorus glass), etc. can be used. The insulating layer may be formed by stacking a plurality of insulating films made of the above-mentioned materials.

[0194] The method for forming the insulating layer 4021 is not particularly limited, and may be a sputtering method, a sintering method, or the like, depending on the material. Pin coat method, dipping method, spray coating, droplet ejection method (inkjet method, screen printing, offset printing, etc.), roll coating, curtain coating, knife coating Coating etc. can be used.

[0195] A display device transmits light from a light source or a display element to display an image. All thin films such as the substrate, insulating film, and conductive film installed in the part are designed to be transparent to light in the visible light wavelength range. It shall be translucent.

[0196] A first electrode layer 4030 and a second electrode layer 4031 (pixel electrode layer) for applying a voltage to a display element In the case of the layer (also called the common electrode layer, counter electrode layer, etc.), the direction of the light to be extracted and the electrode layer are provided. The light transmission or reflection can be selected depending on the location where the electrode layer is to be disposed and the pattern structure of the electrode layer.

[0197] The first electrode layer 4030 and the second electrode layer 4031 are made of indium oxide containing tungsten oxide. oxide, indium zinc oxide with tungsten oxide, indium oxide with titanium oxide Indium tin oxide containing titanium oxide, ITO, indium zinc oxide, silicon oxide A light-transmitting conductive material such as indium tin oxide doped with ruthenium can be used.

[0198] The first electrode layer 4030 and the second electrode layer 4031 are made of tungsten (W) or molybdenum. (Mo), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (N b) Tantalum (Ta), Chromium (Cr), Cobalt (Co), Nickel (Ni), Titanium Metals such as titanium (Ti), platinum (Pt), aluminum (Al), copper (Cu), and silver (Ag), Or, it can be formed by using one or more of its alloys or nitrides. .

[0199] The first electrode layer 4030 and the second electrode layer 4031 are made of a conductive polymer (conductive polymer). The conductive polymer may be a conductive composition containing a conductive polymer. For example, a so-called π-electron conjugated conductive polymer can be used. or its derivatives, polypyrrole or its derivatives, polythiophene or its derivatives, or a copolymer of two or more of aniline, pyrrole and thiophene or a derivative thereof Conductors, etc.

[0200] In addition, since transistors are easily damaged by static electricity, etc., a protection circuit for protecting the driver circuit is also required. It is preferable that the protection circuit is configured using a non-linear element.

[0201] As described above, by using the transistor described in Embodiment 1 or 2, various functions can be realized. It is possible to provide a semiconductor device having the above structure.

[0202] (Embodiment 4) By using the transistor as an example shown in either the first or second embodiment, information on the object is A semiconductor device having an image sensor function for reading can be manufactured.

[0203] FIG. 6A shows an example of a semiconductor device having an image sensor function. FIG. 6(B) is a cross-sectional view showing a part of the photosensor.

[0204] The photodiode 602 has one electrode connected to a photodiode reset signal line 658 and the other One electrode of the transistor 640 is electrically connected to the gate of the transistor 640. One of the source or drain is connected to the photosensor reference signal line 672, and the other of the source or drain is connected to the photosensor reference signal line 672. The other terminal is electrically connected to one of the source and drain terminals of the transistor 656. The transistor 656 has a gate connected to a gate signal line 659 and a source or drain connected to a photodiode. The sensor output signal line 671 is electrically connected to the sensor output signal line 671.

[0205] Note that in the circuit diagrams in this specification, a transistor including an oxide semiconductor film is not clearly shown. To make it easy to understand, the symbol for a transistor using an oxide semiconductor film is marked with “OS.” In FIG. 6A, the transistor 640 and the transistor 656 are formed using an oxide semiconductor film. This is a transistor that uses

[0206] FIG. 6B illustrates a photodiode 602 and a transistor 640 in the photosensor. 6 is a cross-sectional view showing a TFT substrate 601 having an insulating surface, on which a TFT substrate 602 is formed. A photodiode 602 and a transistor 640 are provided. A substrate 613 is provided on the board 602 and the transistor 640 using an adhesive layer 608. do.

[0207] On the transistor 640, a metal oxide film 631 for preventing charging, an insulating film 632, and an interlayer An insulating layer 633 and an interlayer insulating layer 634 are provided. An electrode layer 641 is formed on the edge layer 633 and on the interlayer insulating layer 633. 34, a first semiconductor layer 6 is disposed between the electrode layer 642 and the interlayer insulating layer 633. 6. The semiconductor layer 606a, the second semiconductor layer 606b, and the third semiconductor layer 606c are stacked. .

[0208] In the transistor 640, the oxide semiconductor film is formed through a metal oxide film 631 stacked thereon. After forming an insulating film 632 on the metal oxide film 631, a heat treatment is performed. This removes impurities such as hydrogen, moisture, hydroxyl groups, and hydrides (also called hydrogen compounds). The oxide semiconductor film is a highly purified oxide semiconductor film that is intentionally removed from the oxide semiconductor film. As a result, a bond between a metal constituting the oxide semiconductor and hydrogen or a bond between the metal and a hydroxyl group can be formed. The bonds of these hydrogen atoms are broken, and these hydrogen or hydroxyl groups react with oxygen to produce water. In order to synthesize the hydrogen and hydroxyl groups, which are impurities, the hydrogen and hydroxyl groups are converted into water by the subsequent heat treatment. This can facilitate the detachment.

[0209] Since oxygen is introduced into the oxide semiconductor film through the stacked metal oxide film 631, The oxygen introduction depth (introduction region) can be controlled, and oxygen can be efficiently introduced into the oxide semiconductor film. It can be introduced.

[0210] In addition, heat treatment was performed in a state where the oxide semiconductor film was in contact with the metal oxide film 631 containing oxygen. Therefore, the main component material that constitutes the oxide semiconductor is reduced at the same time as the impurity removal process. Oxygen, which is one of the oxygen-containing metal oxide films, is supplied to the oxide semiconductor film from the metal oxide film 631 containing oxygen. As a result, the oxide semiconductor film becomes more highly purified and electrically i-type (intrinsic).

[0211] Therefore, the transistor 640 including the highly purified oxide semiconductor film has little fluctuation in electrical characteristics. Therefore, the semiconductor device according to the present embodiment is highly reliable. It is possible to provide a semiconductor device with high performance.

[0212] The electrode layer 641 is electrically connected to a conductive layer 643 formed on the interlayer insulating layer 634. 642 is electrically connected to a gate electrode 645 via an electrode layer 644. 45 is electrically connected to the gate electrode of the transistor 640 and the photodiode 6 02 is electrically connected to a transistor 640 .

[0213] Here, the first semiconductor layer 606a is a semiconductor layer having a p-type conductivity, and the second semiconductor layer 606b is a high resistance semiconductor layer (I-type semiconductor layer), and the third semiconductor layer 606c is an n-type A pin-type photodiode in which semiconductor layers having different conductivity types are stacked is shown as an example.

[0214] The first semiconductor layer 606a is a p-type semiconductor layer, and is an amorphous semiconductor layer containing an impurity element that imparts p-type. The first semiconductor layer 606a can be formed of a silicon film. Using semiconductor material gas containing impurity elements (e.g. boron (B)), plasma CVD method Silane (SiH4) can be used as the semiconductor material gas. i2H6, SiH2Cl2, SiHCl3, SiCl4, SiF4, etc. may also be used. In addition, after forming an amorphous silicon film that does not contain impurity elements, the film is then subjected to diffusion or ion implantation. Impurity elements may be introduced into the amorphous silicon film by using an ion implantation method or the like. It is preferable to diffuse the impurity element by heating or the like after introducing the impurity element. In this case, the method for forming the amorphous silicon film includes the LPCVD method, the vapor phase growth method, Alternatively, a sputtering method or the like may be used. The thickness of the first semiconductor layer 606a is 10 nm or more and 5 It is preferable to form the film so that the thickness is 0 nm or less.

[0215] The second semiconductor layer 606b is an I-type semiconductor layer (intrinsic semiconductor layer) and is made of amorphous silicon. The second semiconductor layer 606b is formed by using a semiconductor material gas. A fast silicon film is formed by plasma CVD. The semiconductor material gas is silane. (SiH4) can be used. Alternatively, Si2H6, SiH2Cl2, SiHCl3, S iCl4, SiF4, etc. may be used. The second semiconductor layer 606b is formed by LPCVD. The second semiconductor layer 606b may be formed by vapor deposition, sputtering, or the like. It is preferable to form the film so that the thickness is 00 nm or more and 1000 nm or less.

[0216] The third semiconductor layer 606c is an n-type semiconductor layer, and is an amorphous material containing an impurity element that imparts n-type conductivity. The third semiconductor layer 606c is formed of a fast silicon film. It is formed by the plasma CVD method using a semiconductor material gas containing silicon (e.g. phosphorus (P)). Silane (SiH4) can be used as the semiconductor material gas. SiH2Cl2, SiHCl3, SiCl4, SiF4, etc. may also be used. After forming an amorphous silicon film that does not contain elements, the material is then doped with silicon using diffusion or ion implantation. An impurity element may be introduced into the amorphous silicon film by ion implantation or the like. After the element is introduced, the impurity element may be diffused by heating or the like. The method for forming the amorphous silicon film includes the LPCVD method, the vapor phase growth method, or the sputtering method. The thickness of the third semiconductor layer 606c is 20 nm or more and 200 nm or less. It is preferable to form it so that the bottom is facing downward.

[0217] The first semiconductor layer 606a, the second semiconductor layer 606b, and the third semiconductor layer 606c are Instead of an amorphous semiconductor, a polycrystalline semiconductor may be used. Semiconductor Amorphous Semiconductor (SAS) It may be formed using a conductor.

[0218] Microcrystalline semiconductors are metastable, intermediate between amorphous and single crystal, when considering the Gibbs free energy. In other words, a semiconductor that has a third state that is stable in terms of free energy The crystals are of a short-range order and have lattice distortion. Microcrystalline silicon, a typical example of a microcrystalline semiconductor, is a type of Raman The spectrum shows single crystal silicon at 520 cm -1It is shifted to the lower wavenumber side. That is, 520 cm, which indicates single crystal silicon. -1 and 480 cm, which indicates amorphous silicon. - 1 The Raman spectrum of microcrystalline silicon has a peak between the dangling bonds. To terminate the aryl group, at least 1 atomic % or more of hydrogen or halogen is contained. Furthermore, rare gas elements such as helium, argon, krypton, and neon are added to create lattice distortion. By further promoting this, the stability is increased, and a favorable microcrystalline semiconductor film can be obtained.

[0219] This microcrystalline semiconductor film is formed by a high-frequency plasma CVD method with a frequency of several tens to several hundreds of MHz. Alternatively, it can be formed by a microwave plasma CVD apparatus with a frequency of 1 GHz or more. Representative examples include SiH4, Si2H6, SiH2Cl2, SiHCl3, SiCl4, and S It can be formed by diluting silicon-containing gas such as iF4 with hydrogen. and hydrogen, and one or more selected from helium, argon, krypton, and neon. A microcrystalline semiconductor film can be formed by diluting the silicon with a rare gas element. The flow rate ratio of hydrogen to the contained gas is 5 to 200 times, preferably 50 to 150 times. Hereinafter, it is more preferable to set it to 100 times. Furthermore, when CH4, C Carbide gas such as 2H6, germanium-containing gas such as GeH4, GeF4, F2, etc. are mixed in. This may be allowed.

[0220] In addition, the mobility of holes generated by the photoelectric effect is smaller than that of electrons, so Photodiodes exhibit better characteristics when the p-type semiconductor layer side is used as the light receiving surface. From the surface of the substrate 601 on which the in-type photodiode is formed, the photodiode 602 The example shows how the light 622 received by the semiconductor layer is converted into an electrical signal. Since the light from the semiconductor layer side having the conductivity type of the 1st order becomes disturbance light, the semiconductor layer side serving as the light receiving surface is different from the light receiving surface. The electrode layer on the side of the semiconductor layer having the opposite conductivity type may be formed using a conductive film having a light-shielding property. The n-type semiconductor layer side can also be used as the light receiving surface.

[0221] The metal oxide film 631 is a gallium oxide film formed by a sputtering method. Also, a film of gallium oxide with indium or zinc added thereto may be used. A gallium oxide film containing 0.01 to 5 atomic percent of indium or zinc can be used. By adding tungsten or zinc, the electrical conductivity of the metal oxide film 631 is improved, and the electrical conductivity of the metal oxide film 631 is improved. The accumulation of load can be further reduced.

[0222] The insulating film 632 may be a silicon oxide layer, a silicon oxynitride layer, an aluminum oxide layer, or an oxide insulating layer such as an aluminum oxynitride layer, a silicon nitride layer, a silicon nitride oxide layer, A single layer or a stack of nitride insulating layers such as an aluminum nitride layer or an aluminum nitride oxide layer can be used.

[0223] The interlayer insulating layers 633 and 634 function as planarizing insulating films to reduce surface irregularities. The interlayer insulating layers 633 and 634 are preferably made of, for example, polyimide or acrylic. Organic insulating materials such as resin, benzocyclobutene resin, polyamide, and epoxy resin are used. In addition to the above organic insulating materials, low-k materials, siloxane, Single layer or laminate of polyimide resin, PSG (phosphorus glass), BPSG (borophosphorus glass), etc. It can be used.

[0224] The insulating film 632, the interlayer insulating layer 633, and the interlayer insulating layer 634 are made of an insulating material. Depending on the material, sputtering, spin coating, dipping, spray coating, Droplet ejection method (inkjet method, screen printing, offset printing, etc.), roll coating The coating can be performed by coating, curtain coating, knife coating, or the like.

[0225] By detecting light 622 incident on the photodiode 602, information on the detected object is obtained. When reading the information of the detected object, a light source such as a backlight is used. It can be used.

[0226] The transistor 640 is the transistor shown in the first or second embodiment. Impurities such as hydrogen, moisture, hydroxyl groups, and hydrides (also called hydrogen compounds) can be removed. A transistor including a highly purified oxide semiconductor film that is intentionally removed from an oxide semiconductor film The transistor has a suppressed change in electrical characteristics and is electrically stable. In the transistor having a metal oxide film for preventing the back channel of an oxide semiconductor film, In addition, the generation of a parasitic channel on the oxide side of the transistor can be prevented. By preventing the occurrence of a parasitic channel on the back channel side of the semiconductor film, the change in threshold voltage is Therefore, a highly reliable semiconductor device can be provided.

[0227] This embodiment mode can be implemented in appropriate combination with the configurations described in other embodiments. It is.

[0228] (Embodiment 5) The liquid crystal display device disclosed in this specification can be applied to various electronic devices (including gaming machines). The electronic device can be, for example, a television device (television or television (also called digital receivers), computer monitors, digital cameras, digital video cameras, etc. Cameras such as digital cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices) (c) Portable game machines, personal digital assistants, audio playback devices, large game machines such as pachinko machines, etc. Examples of electronic devices including the liquid crystal display device described in the above embodiment include: He explains.

[0229] FIG. 7A shows an electronic book (also called an E-book), which includes a housing 9630 and a display portion 9631. , an operation key 9632, a solar cell 9633, and a charge / discharge control circuit 9634. The electronic book shown in Fig. 7(A) displays various information (still images, videos, text images, etc.). A function to display a calendar, date, or time on the display unit, a function to display a date, time, or other information on the display unit, The ability to manipulate or edit information, and control processing through various software (programs) Note that FIG. 7A shows an example of a charge and discharge control circuit 9634. The battery 9635 and the DCDC converter (hereafter referred to as the converter) 9636 are used. The semiconductor device shown in any one of the first to fourth embodiments is shown. By applying this to the unit 9631, it is possible to make the electronic book highly reliable.

[0230] By using the structure shown in FIG. 7A, the display portion 9631 can be a semi-transmissive or reflective type. When using a liquid crystal display device, it is expected that it will be used in relatively bright conditions, so solar cells 9633 This is preferable because it allows efficient power generation by the solar cell and charging of the battery 9635. The solar cell 9633 can be appropriately installed in the empty space (front or back) of the housing 9630. This is preferable because it allows for efficient charging of the Battery 9635. It is suitable for battery 9635. If a lithium-ion battery is used, it will be possible to reduce the size. It has the advantage that it can be easily measured.

[0231] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 7A are shown in FIG. A block diagram is shown and explained. In FIG. 7(B), a solar cell 9633, a battery 9635, A converter 9636, a converter 9637, switches SW1 to SW3, and a display unit 9631 The figure shows the Battery 9635, Converter 9636, Converter 9637, and Switches SW1 to SW3 correspond to the charge / discharge control circuit 9634.

[0232] First, an example of operation in which power is generated by the solar cell 9633 using external light will be described. The power generated by the solar cell 9633 becomes the voltage for charging the battery 9635. The voltage is increased or decreased by a converter 9636. When power is being used from the solar cell 9633, switch SW1 is turned on and the converter 9 637 raises or lowers the voltage to the voltage required for the display unit 9631. When not displaying on the 9631, turn SW1 off and SW2 on to power the battery. It would be best to configure it to charge the 9635.

[0233] Next, an example of operation when power is not generated by the solar cell 9633 due to external light will be described. The power stored in the Battery 9635 is converted by turning on the switch SW3. The voltage is increased or decreased by the power supply 9637. Power will be drawn from Lee 9635.

[0234] Although the solar cell 9633 is shown as an example of a charging means, the battery may be charged by other means. It may be configured to charge the Terry 9635. It may also be configured to charge the Terry 9635 in combination with other charging means. This may also be configured.

[0235] FIG. 8A shows a notebook personal computer, which includes a main body 3001 and a housing 3002. , a display unit 3003, a keyboard 3004, etc. By applying the semiconductor device shown in any one of the above items 1 to 4 to the display portion 3003, It may be a notebook type personal computer.

[0236] FIG. 8B shows a portable digital assistant (PDA), which has a main body 3021 including a display unit 3023 and an external The external interface 3025 and the operation buttons 3024 are also provided. The accessory includes a stylus 3022. By applying the device to the display unit 3023, a more reliable personal digital assistant (PDA) can be manufactured. It can be said that:

[0237] FIG. 8C shows an example of an electronic book. For example, an electronic book 2700 has a housing 270 The housing 2701 and the housing 2703 are two housings. The opening and closing operations are performed with the shaft portion 2711 as an axis. With this configuration, it becomes possible to operate like a paper book.

[0238] A display unit 2705 is incorporated in the housing 2701, and a display unit 2707 is incorporated in the housing 2703. The display unit 2705 and the display unit 2707 are configured to display a continuous screen. Alternatively, a different screen may be displayed. For example, a text is displayed on the right display unit (display unit 2705 in FIG. 8C) and An image can be displayed on the display unit (the display unit 2707 in FIG. 8C). The semiconductor device shown in any one of the above to 4 is applied to the display portion 2705 and the display portion 2707. This makes it possible to make the e-book more reliable.

[0239] FIG. 8C shows an example in which an operation unit and the like are provided in the housing 2701. The body 2701 includes a power source 2721, operation keys 2723, a speaker 2725, etc. The operation keys 2723 can be used to turn pages. A keyboard and a pointing device may be provided on the rear of the housing. On the front and sides, there are external connection terminals (earphone terminal, USB terminal, etc.), a recording medium insertion part, etc. Furthermore, the electronic book 2700 may have a function as an electronic dictionary. The above configuration may also be used.

[0240] The electronic book 2700 may be configured to transmit and receive information wirelessly. The desired book data can be purchased and downloaded from the electronic book server. is also possible.

[0241] FIG. 8D shows a mobile phone, which is composed of two housings, a housing 2800 and a housing 2801. The housing 2801 includes a display panel 2802, a speaker 2803, a microphone, and a 2804, pointing device 2806, camera lens 2807, external connection terminal 2 808. The housing 2800 also includes a solar cell for charging the mobile phone. 2810, an external memory slot 2811, etc. The semiconductor device according to any one of the first to fourth embodiments is mounted on a display panel. By applying this to the mobile phone 2802, it is possible to create a highly reliable mobile phone.

[0242] The display panel 2802 is equipped with a touch panel, and in FIG. The multiple operation keys 2805 are indicated by dotted lines. It also implements a boost circuit to boost the voltage supplied to each circuit to the voltage required.

[0243] The display direction of the display panel 2802 changes appropriately depending on the usage mode. Since it has a camera lens 2807 on the same surface as 2802, video telephony is possible. The speaker 2803 and the microphone 2804 are not limited to voice calls, but can also be used for video calls, Recording and playback are possible. Furthermore, the housing 2800 and the housing 2801 can be slid. It can be folded from the unfolded state as shown in 8(D) to the overlapped state, making it convenient to carry. It is possible to reduce the size.

[0244] The external connection terminal 2808 can be connected to various cables such as AC adapters and USB cables. It is possible to charge the battery and to communicate data with a personal computer, etc. A recording medium can be inserted into the memory slot 2811 to accommodate larger amounts of data storage and transfer. do.

[0245] In addition to the above functions, even if the device has infrared communication function, TV reception function, etc. good.

[0246] FIG. 8(E) shows a digital video camera, which includes a main body 3051, a display unit (A) 3057, and a connection Eye part 3053, operation switch 3054, display part (B) 3055, battery 3056, etc. The semiconductor device according to any one of the first to fourth embodiments is configured as a display unit ( By applying A) 3057 and display (B) 3055, it is possible to realize highly reliable digital video. It can be used as a camera.

[0247] FIG. 8F shows an example of a television device. The television device 9600 is A display unit 9603 is built into the body 9601. The display unit 9603 displays images. In this embodiment, the housing 9601 is supported by a stand 9605. The semiconductor device described in any one of Embodiments 1 to 4 includes a display portion 9603 By applying the present invention to the television set, a highly reliable television set can be obtained.

[0248] The television device 9600 can be operated using an operation switch on the housing 9601 or a separate remote control. The remote control can also be operated by the remote control. A display unit for displaying the output information may be provided.

[0249] The television device 9600 includes a receiver and a modem. It can receive more general television broadcasts, and can also be connected to a modem via wired or wireless connection. By connecting to a network, communication can be one-way (sender to receiver) or two-way. It is also possible to communicate information (between a sender and a receiver, or between receivers).

[0250] This embodiment mode can be implemented in appropriate combination with the configurations described in other embodiments. It is. [Explanation of symbols]

[0251] 400 Substrates 401 Gate electrode 402 Gate insulating film 403 Oxide Semiconductor Film 405a Source electrode 405b Drain electrode 407 Metal oxide film 409 Insulating film 410 Transistor 421 Oxygen 441 Oxide Semiconductor Film 601 Substrate 602 Photodiode 606a Semiconductor layer 606b Semiconductor layer 606c Semiconductor layer 608 Adhesive layer 613 Substrate 631 Metal oxide film 632 Insulating film 633 Interlayer Insulation Layer 634 Interlayer insulation layer 640 Transistor 641 Electrode layer 642 Electrode layer 643 Conductive Layer 645 Gate electrode 656 Transistor 658 Photodiode reset signal line 659 Gate signal line 671 Photo sensor output signal line 672 Photosensor reference signal line 2700 e-books 2701 Case 2703 Case 2705 ​​Display section 2707 Display section 2711 Shaft 2721 Power supply 2723 Operation key 2725 Speaker 2800 Chassis 2801 Case 2802 Display Panel 2803 Speaker 2804 Microphone 2805 Operation key 2806 Pointing Device 2807 Camera lenses 2808 External connection terminal 2810 Solar Cell 2811 External memory slot 3001 Main unit 3002 Case 3003 Display section 3004 Keyboard 3021 Main unit 3022 Stylus 3023 Display section 3024 Operation button 3025 External Interface 3051 Main unit 3053 Eyepiece 3054 Operation switch 3055 Display section (B) 3056 Battery 3057 Display section (A) 4001 Board 4002 Pixel section 4003 Signal line driver circuit 4004 Scanning line driver circuit 4005 Sealing material 4006 Substrate 4008 Liquid crystal layer 4010 Transistor 4011 Transistor 4013 Liquid crystal element 4015 Connection terminal electrode 4016 Terminal electrode 4018 FPC 4019 Anisotropic conductive film 4020 Metal oxide film 4021 Insulation layer 4023 Insulating film 4024 Insulating film 4030 Electrode layer 4031 Electrode layer 4032 Insulating film 4033 Insulating film 4510 Bulkhead 4511 Electroluminescent layer 4513 Light emitting element 4514 Filling material 4612 Cavity 4613 Spherical particles 4614 Filling material 4615a Black area 4615b White area 9600 Television Equipment 9601 Case 9603 Display section 9605 Stand 9630 Case 9631 Display section 9632 Operation key 9633 Solar Cells 9634 Charge / discharge control circuit 9635 Battery 9636 Converter 9637 Converter

Claims

[Claim 1] A gate electrode is formed on the substrate. forming a gate insulating film covering the gate electrode; forming an oxide semiconductor film in a region overlapping with the gate electrode via the gate insulating film; forming a source electrode and a drain electrode on the oxide semiconductor film; forming a metal oxide film in contact with the oxide semiconductor film and covering the source electrode and the drain electrode; introducing oxygen into at least one of the oxide semiconductor film, the metal oxide film, or an interface between the oxide semiconductor film and the metal oxide film; forming an insulating film covering the metal oxide film; A method for manufacturing a semiconductor device which performs heat treatment.

Images