Semiconductor device

Abstract

To suppress fluctuation in electrical characteristics and improve reliability in a semiconductor device having an oxide semiconductor.SOLUTION: A semiconductor device has an oxide semiconductor film. The semiconductor device comprises: a first insulation film; an oxide semiconductor film on the first insulation film; a second insulation film on the oxide semiconductor film; and a third insulation film on the second insulation film. The second insulation film contains oxygen and silicon. The third insulation film contains nitrogen and silicon. Indium is contained near a boundary surface between the second insulation film and the third insulation film.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One embodiment of the present invention is a semiconductor device including an oxide semiconductor film and a display device including the semiconductor device. This relates to a display device.

[0002] Note that one embodiment of the present invention is not limited to the above technical fields. The technical field of one aspect of the present invention relates to a product, a method, or a manufacturing method. process, machine, manufacture, or composition of matter In particular, one embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, The present invention relates to a device, a driving method thereof, or a manufacturing method thereof. [Background technology]

[0003] A transistor (field-effect transistor) is made using a semiconductor thin film formed on a substrate with an insulating surface. The technology that makes up the field-effect transistor (FET) or thin-film transistor (TFT) is attracting attention. The transistor is used in integrated circuits (ICs) and image display devices (display devices). It is widely used in electronic devices. Silicon is a semiconductor thin film that can be used in transistors. Semiconductor materials such as silicon are widely known, but oxide semiconductors are also attracting attention. It has been attracting attention (for example, Patent Document 1).

[0004] In addition, a base insulating layer of the oxide semiconductor layer in which a channel is formed is heated to release oxygen. A semiconductor device that uses an insulating layer to reduce oxygen vacancies in the oxide semiconductor layer has been disclosed (e.g., For example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-165529 A [Patent Document 2] JP 2012-9836 A Summary of the Invention [Problem to be solved by the invention]

[0006] When a transistor is manufactured by using an oxide semiconductor film for a channel region, Oxygen vacancies formed in the channel region during semiconductor manufacturing are problematic because they affect transistor characteristics. For example, when oxygen vacancies are formed in a channel region in an oxide semiconductor film, the oxygen vacancies Hydrogen bonds to the oxide semiconductor film and becomes a carrier supply source. When a supply source is generated, the electrical characteristics of a transistor including an oxide semiconductor film are changed, typically. In addition, the electrical characteristics of each transistor vary. Therefore, in the channel region of the oxide semiconductor film, oxygen vacancies are small. The more the better.

[0007] In view of the above problems, one embodiment of the present invention is a semiconductor device including an oxide semiconductor. One of the objectives is to suppress the fluctuation of characteristics and improve reliability. An object of one embodiment of the present invention is to provide a semiconductor device with reduced power consumption. Another object of one embodiment of the present invention is to provide a novel semiconductor device. An object of one embodiment of the present invention is to provide a novel display device.

[0008] The above description of the problem does not preclude the existence of other problems. The embodiment does not necessarily have to solve all of these problems. Problems other than those mentioned above may be solved by the specification. The above problems are obvious from the description of the specification, etc., and problems other than those mentioned above cannot be extracted from the description of the specification, etc. It is possible to issue it. [Means for solving the problem]

[0009] One embodiment of the present invention is a semiconductor device including an oxide semiconductor film, an insulating film, an oxide semiconductor film on the first insulating film, and a second insulating film on the oxide semiconductor film; and a third insulating film on the second insulating film, the second insulating film containing oxygen and silicon. The third insulating film contains nitrogen and silicon, and the second insulating film and the third insulating film The semiconductor device is characterized by having indium in the vicinity of the interface.

[0010] Another embodiment of the present invention is a semiconductor device including an oxide semiconductor film, The device includes a gate electrode, a first insulating film on the gate electrode, and an oxide semiconductor film on the first insulating film. a source electrode electrically connected to the oxide semiconductor film; a drain electrode formed on the oxide semiconductor film, a source electrode, and a second insulating film on the drain electrode; a third insulating film on the second insulating film, the second insulating film being composed of oxygen, silicon and , the third insulating film has nitrogen and silicon, and the second insulating film and the third insulating film The semiconductor device is characterized by having indium in the vicinity of the interface with the film.

[0011] In each of the above configurations, indium is preferably detected by secondary ion mass spectrometry.

[0012] In each of the above structures, the oxide semiconductor film contains oxygen, In, Zn, and M (M is It is preferable that the metal oxide has at least one of Ti, Ga, Sn, Y, Zr, La, Ce, Nd, or Hf. In each of the above structures, the oxide semiconductor film has a crystal part, and the crystal part has a c-axis It is preferable that the oxide semiconductor film have a part that is parallel to a normal vector of a surface on which the oxide semiconductor film is formed.

[0013] Another embodiment of the present invention is a semiconductor device and a display element according to any one of the above structures. Another embodiment of the present invention is a display device including the display device and a touch sensor. Another embodiment of the present invention is a display module having any one of the above structures. The semiconductor device according to any one of claims 1 to 5, the display device, or the display module, and an operation key or and a battery. Effect of the Invention

[0014] According to one embodiment of the present invention, a change in electrical characteristics of a semiconductor device including an oxide semiconductor can be prevented. According to one embodiment of the present invention, the consumption of electricity can be suppressed and the reliability can be improved. A semiconductor device with reduced power consumption can be provided. According to one embodiment of the present invention, a novel semiconductor device can be provided. A display device can be provided.

[0015] The description of these effects does not preclude the existence of other effects. An embodiment does not necessarily have to have all of these effects. The above will become apparent from the description in the specification, drawings, claims, etc. It is possible to extract other effects from the descriptions in the claims, etc. [Brief description of the drawings]

[0016] [Figure 1] 1A and 1B are a top view and a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 2] 1A to 1C are cross-sectional views illustrating one embodiment of a semiconductor device and an example of a manufacturing process of the semiconductor device. [Diagram 3] FIG. 1 is a diagram illustrating the results of SIMS analysis. [Figure 4] 1A and 1B are a top view and a cross-sectional view illustrating one embodiment of a semiconductor device. [Diagram 5] 1A and 1B are a top view and a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 6] 1A and 1B are a top view and a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 7] FIG. 1 is a cross-sectional view illustrating one embodiment of a semiconductor device. [Figure 8] FIG. 2 is a diagram for explaining a band structure. [Figure 9] 1A to 1C are cross-sectional views illustrating an example of a manufacturing process of a semiconductor device. [Figure 10] 1A to 1C are cross-sectional views illustrating an example of a manufacturing process of a semiconductor device. [Figure 11] 1A to 1C are cross-sectional views illustrating an example of a manufacturing process of a semiconductor device. [Figure 12] 1A to 1C are cross-sectional views illustrating an example of a manufacturing process of a semiconductor device. [Figure 13] 1A to 1C are cross-sectional views illustrating an example of a manufacturing process of a semiconductor device. [Figure 14] 1A to 1C are cross-sectional views illustrating an example of a manufacturing process of a semiconductor device. [Figure 15] FIG. 1 is a top view illustrating one embodiment of a display device. [Figure 16] FIG. 1 is a cross-sectional view showing one embodiment of a display device. [Figure 17] FIG. 1 is a cross-sectional view showing one embodiment of a display device. [Figure 18] 1A and 1B are a block diagram and a circuit diagram illustrating a display device. [Figure 19] FIG. 2 is a diagram illustrating a display module. [Figure 20] 1A to 1C are diagrams illustrating electronic devices. [Figure 21] 1A to 1C are cross-sectional views illustrating an analysis sample and a transistor structure in an embodiment. [Figure 22] 4A to 4C are diagrams illustrating the results of SIMS analysis in the examples. [Figure 23] 13A to 13C show electrical characteristics of a transistor in an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, the embodiments will be described with reference to the drawings. It is possible to carry out the present invention in various forms without departing from the spirit and scope of the present invention. It will be readily understood by those skilled in the art that various modifications may be made to the details of the present invention. However, the present invention should not be construed as being limited to the description of the following embodiments.

[0018] Also, in the drawings, the size, layer thickness, or area are exaggerated for clarity. Therefore, the scale is not necessarily limited to that shown in the drawings. The drawings are merely schematic illustrations and are not limited to the shapes or values ​​shown in the drawings.

[0019] In addition, in this specification and the like, ordinal numbers such as 1st, 2nd, etc. are used for convenience. It does not indicate the order of processes or stacking. For example, "first" may be changed to "second In addition, the terms "the" or "the third" may be used interchangeably in the description of the present specification. The ordinal numbers listed in the specification do not match the ordinal numbers used to identify an aspect of the present invention. There are cases.

[0020] In addition, in this specification, the words "above" and "below" indicating the position of the components are used. The positional relationship is used for convenience in describing the drawings. The relationship changes depending on the direction in which each component is depicted. The above words and phrases are not limited to those used above, but can be rephrased appropriately depending on the situation.

[0021] In this specification and the like, a semiconductor device is a device that can function by utilizing semiconductor characteristics. Refers to devices in general. Semiconductor elements such as transistors, semiconductor circuits, computing devices, memory The device is one aspect of a semiconductor device. Optical devices, power generation devices (including thin-film solar cells, organic thin-film solar cells, etc.), and electronic devices The device may include a semiconductor device.

[0022] In this specification, a transistor includes a gate, a drain, and a source. The drain terminal is a diode that has at least three terminals. Between the drain region or drain electrode and the source (source terminal, source region or source electrode) A current flows through the drain, the channel region, and the source. In this specification and the like, the channel region refers to a region through which a current mainly flows. The flow area.

[0023] In addition, the functions of the source and drain may differ depending on whether transistors of different polarities are used or the circuit In operation, when the direction of the current changes, the positions may be reversed. In the specification, the terms source and drain may be used interchangeably. do.

[0024] In addition, in this specification, "electrically connected" means "something that has some kind of electrical effect." This includes cases where the device is connected via a "device having some electrical function." "of" is not subject to any particular restrictions as long as it enables the transmission and reception of electrical signals between connected objects. For example, "something that has an electrical effect" includes electrodes, wiring, and transistors. These devices have various functions such as switching elements, resistor elements, inductors, capacitors, etc. This includes elements such as:

[0025] In this specification and the like, a silicon oxynitride film is a film having a composition containing more oxygen than nitrogen. A silicon nitride film is a film that contains more nitrogen than oxygen. This refers to a film with a high content of.

[0026] In addition, in this specification and the like, the terms "film" and "layer" are interchangeable. For example, the term "conductive layer" can be changed to the term "conductive film." Alternatively, for example, the term "insulating film" may be changed to "insulating layer." It may be possible to change the term to:

[0027] In addition, in this specification, "parallel" means that two straight lines are at an angle of -10° or more and 10° or less. Therefore, it includes the case where the angle is between -5° and 5°. "Approximately parallel" refers to a state in which two straight lines are arranged at an angle of -30° or more and 30° or less. "Perpendicular" means that two straight lines are arranged at an angle of 80° or more and 100° or less. Therefore, it includes the case where the angle is between 85° and 95°. refers to a state in which two straight lines are arranged at an angle of 60° or more and 120° or less.

[0028] In addition, in this specification, the vicinity of the interface means within a range of ±5 nm from the interface. In a state where different films are stacked in the vertical direction, a compound is applied near the interface where the different films contact each other. In this case, the vicinity of the interface refers to the compound and the area 5 nm above the compound. This refers to the combined area of ​​the compound and the area 5 nm below the compound.

[0029] (Embodiment 1) In this embodiment, a semiconductor device of one embodiment of the present invention will be described with reference to FIGS. explain.

[0030] <Configuration Example 1 of Semiconductor Device> FIG. 1A is a top view of a transistor 100 which is a semiconductor device of one embodiment of the present invention. 1B corresponds to a cross-sectional view taken along dashed line X1-X2 in FIG. 1A. FIG. 1C is a cross-sectional view taken along the dashed line Y1-Y2 in FIG. 1A. In FIG. 1A, in order to avoid complication, the transistor 100 Some of the components (such as the insulating film that functions as the gate insulating film) are omitted in the figure. The dashed line X1-X2 direction is the channel length direction, and the dashed line Y1-Y2 direction is the channel width direction. In the top view of the transistor, As in FIG. 1(A), some of the components may be omitted.

[0031] The transistor 100 includes a conductive film 104 that functions as a first gate electrode on a substrate 102. an insulating film 106 on the substrate 102 and the conductive film 104; and an insulating film 107 on the insulating film 106. The oxide semiconductor film 108 over the insulating film 107 and the insulating film 108 electrically connected to the oxide semiconductor film 108 The conductive film 112a serving as a source electrode and the oxide semiconductor film 108 are electrically connected to and a conductive film 112b serving as a drain electrode connected to the conductive film 112a. Insulating films 114, 116, and 118 are provided over the oxide semiconductor film 112b and the oxide semiconductor film 108. The insulating films 114, 116, and 118 serve as protective insulating films for the transistor 100. It has functions.

[0032] In addition, the transistor 100 includes indium in the vicinity of the interface between the insulating film 116 and the insulating film 118. In other words, indium is detected near the interface between the insulating film 116 and the insulating film 118. The reason why indium is detected will be described later.

[0033] The insulating film 106 and the insulating film 107 serve as a gate insulating film of the transistor 100. Note that the insulating films 106 and 107 are referred to as a first insulating film, and the insulating films 114 and In the case where the insulating film 116 is referred to as a second insulating film and the insulating film 118 is referred to as a third insulating film, There is a match.

[0034] When oxygen vacancies are formed in the oxide semiconductor film 108 of the transistor 100, a carrier Therefore, the oxide semiconductor film 1 tends to have a normally-on characteristic. Reducing oxygen vacancies in O8 is also important for obtaining stable transistor characteristics. In the structure of the transistor according to one embodiment of the present invention, the insulating film over the oxide semiconductor film 108 In this example, excess oxygen is introduced into the insulating film 114 over the oxide semiconductor film 108, Oxygen is transferred from 114 to the oxide semiconductor film 108, and oxygen vacancies in the oxide semiconductor film 108 are eliminated. Alternatively, the insulating film 116 over the oxide semiconductor film 108 is provided with an excess By introducing oxygen, the insulating film 116 and the oxide semiconductor film 108 through the insulating film 114 are The oxide semiconductor film 108 is characterized in that oxygen is transferred thereinto to fill oxygen vacancies therein. Alternatively, excess oxygen is introduced into the insulating film 114 and the insulating film 116 over the oxide semiconductor film 108. As a result, oxygen is transferred from both the insulating film 114 and the insulating film 116 to the oxide semiconductor film 108. The oxygen vacancies in the oxide semiconductor film 108 are filled by the oxygen vacancies.

[0035] Therefore, the insulating films 114 and 116 contain oxygen. More specifically, the insulating films 114 and 116 preferably contain oxygen and silicon. In the case of the stoichiometric composition, there is a region (oxygen excess region) that contains oxygen in excess of the stoichiometric composition. In this case, the insulating films 114 and 116 are insulating films capable of releasing oxygen. In order to provide an oxygen excess region in the insulating films 114 and 116, for example, Oxygen is introduced into the substrate 6 to form an oxygen excess region. The oxygen introduction method is an ion implantation method. By using ion doping, plasma immersion ion implantation, plasma treatment, etc. The plasma treatment can be carried out by converting oxygen gas into plasma using high-frequency power. The plasma etching equipment or plasma ashing equipment is used. It is preferable that:

[0036] The amount of oxygen molecules released from the insulating film capable of releasing oxygen is calculated based on the temperature rise desorption rate. Thermal Desorption Spectroscopy (TDS) For example, the insulating films 114 and 116 can be measured using TDS. When measured, the amount of oxygen molecules released was 1×10 19 pieces / cm 3 It is preferable that the above is the case. The substrate temperature in TDS is 100°C to 700°C or 100°C to 500°C. A range of 00°C or less is preferred.

[0037] In one embodiment of the present invention, in order to form an oxygen excess region in the insulating films 114 and 116, For this purpose, a film capable of suppressing oxygen release is formed on the insulating film 116, and The feature is that oxygen is introduced into the insulating films 114 and 116. The release of oxygen can be suppressed. The functional film may be a conductive film containing indium or a semiconductor film containing indium. In addition, the film having the function of suppressing the release of oxygen is preferably removed after the introduction of oxygen. It is preferable to do so.

[0038] Examples of films that have the function of suppressing oxygen release include films made of indium (In) and zinc (Ni). Lead (Zn), tin (Sn), tungsten (W), titanium (Ti), or silicon (Si In particular, a material containing one selected from the group consisting of those capable of suppressing the release of oxygen can be used. Examples of films that can be used include indium oxide containing tungsten oxide, tungsten oxide, Indium zinc oxide containing titanium oxide, indium oxide containing titanium oxide Indium Tin Oxide (IT O), indium zinc oxide, indium tin oxide with silicon oxide Conductive materials with translucency such as Tin SiO2 Doped Oxide (ITSO) Fees may be used.

[0039] In addition, a film capable of suppressing oxygen release is formed over the insulating film 116. When oxygen is introduced into the insulating films 114 and 116, the vicinity of the surface of the insulating film 116, in other words, Indium is detected near the interface between the insulating film 116 and the insulating film 118. This is because of the The film having the function of suppressing emission contains indium, and the insulating films 114 and 11 This is because when oxygen is introduced into the insulating film 116, indium is implanted near the surface of the insulating film 116. do.

[0040] Here, regarding indium detected near the surface of the insulating film 116, using FIG. 2 and FIG. The details are explained below.

[0041] FIG. 2A is a cross-sectional view of a semiconductor device 200, and FIGS. 2B, 2C, and 2D are cross-sectional views of the semiconductor device 200. 4A is a cross-sectional view showing an example of a manufacturing process of the semiconductor device 200 shown in FIG.

[0042] The semiconductor device 200 shown in FIG. 2A includes an insulating film 204 on a substrate 202 and an insulating film 204 and an insulating film 206 thereon.

[0043] In addition, the semiconductor device 200 shown in FIG. 2A is a semiconductor device having a structure in the vicinity of the surface of the insulating film 116 shown in FIG. This is an analytical sample prepared to evaluate the indium emitted from the insulating The film 204 corresponds to the insulating film 116 shown in FIG.

[0044] The substrate 202 is a glass substrate, and the insulating film 204 is an oxide film having a thickness of 400 nm. A silicon oxynitride film is used, and a silicon oxynitride film having a thickness of 200 nm is used as the insulating film 206. was used.

[0045] The semiconductor device 200 shown in FIG. 2A is a semiconductor device according to one embodiment of the present invention, and comparative sample A2 were fabricated, and the indium oxide in the vicinity of the interface between the insulating film 204 and the insulating film 206 was measured. The amount of ruthenium detected was evaluated. The preparation methods of samples A1 and A2 are described below. do.

[0046] <Sample A1> An insulating film 204 is provided on a substrate 202, and a film having a function of suppressing oxygen release is provided on the insulating film 204. A film 230 was formed (see FIG. 2(B)).

[0047] The insulating film 204 was formed by a silane gas having a flow rate of 160 sccm and a substrate temperature of 220° C. Nitrous oxide gas was introduced into the chamber at a flow rate of 4000 sccm, and the pressure was set to 200 Pa. An RF power of 1500 W was supplied between the parallel plate electrodes installed in the PECVD apparatus. The film 230 having the function of suppressing oxygen release was formed by using an IT film having a thickness of 5 nm. The ITSO film was formed using a sputtering system. The composition of the target used for the ITSO film was The composition ratio was In2O3:SnO2:SiO2 = 85:10:5 [wt %].

[0048] Next, oxygen 239 was added from above the film 230 having the function of suppressing oxygen release ( See Figure 2(C).

[0049] The oxygen 239 was added using an ashing device with a flow rate of 250 sccm of oxygen gas. The gas was introduced into the chamber, the pressure was set to 15 Pa, and a bias was applied to the substrate side. The ashing was performed by supplying 4500 W of RF power between the parallel plate electrodes installed in the ashing device. I did.

[0050] Next, the film 230 having the function of suppressing the release of oxygen is removed by an etchant 242. (See FIG. 2(D)).

[0051] The etchant 242 was a 5% aqueous solution of oxalic acid, and the treatment was continued for 300 seconds. Then, the sample was treated with 0.5% hydrofluoric acid for 15 seconds.

[0052] Next, an insulating film 206 is formed on the insulating film 204, and the semiconductor device 200 shown in FIG. The insulating film 206 was formed by depositing silane at a flow rate of 75 sccm at a substrate temperature of 330°C. Gas and nitrous oxide gas at a flow rate of 1200 sccm were introduced into the chamber, and the pressure was set at 70 The RF power was set to 120 W between the parallel plate electrodes installed in the PECVD device. A film was formed by this method.

[0053] <Sample A2> Compared to the previously described sample A1, the sample A2 was not subjected to the oxygen addition treatment shown in FIG. That is, the sample A2 has a film 204 having a function of suppressing oxygen release. After forming 30, the oxygen release can be suppressed without oxygen addition treatment. This is a sample in which the film 230 is removed and the insulating film 206 is formed.

[0054] Next, the insulators 204 and 206 of the samples A1 and A2 were fabricated. To measure the indium concentration, secondary ion mass spectrometry (SIMS) was used. Analysis was performed using ion mass spectrometry. The analysis results of sample A1 and sample A2 are shown in FIG. 3(A) and FIG. 3(B), respectively. In (A) and (B), the horizontal axis represents the depth (nm) and the vertical axis represents the indium concentration (atoms / cm m 3 ), respectively.

[0055] From the results shown in FIGS. 3(A) and 3(B), in the sample A1, the interface between the insulating film 204 and the insulating film 206 There are 5×10 indium particles nearby. 16 atoms / cm 3 It was confirmed at concentrations above 100 mg / kg / day. In the sample A2, indium was 5×1016 a toms / cm 3 In the above SIMS analysis, the detection of indium was The lower limit is 1×10 15 atoms / cm 3 It is.

[0056] In addition, due to the measurement principle, SIMS analysis only collects data near the sample surface or near the stacking interface. However, when comparing sample A1 and sample A2, The amount of indium detected near the interface between the insulating film 204 and the insulating film 206 of the sample A1 was This is larger than the amount of indium detected in the vicinity of the interface between the insulating film 204 and the insulating film 206 in FIG.

[0057] From the results shown in Fig. 3(A) and (B), it can be seen that sample A1 has a function of suppressing oxygen release. Indium in the ITSO film used as the film having the insulating film 204 is converted to indium during the oxygen addition process. On the other hand, in sample A2, the release of oxygen could not be suppressed. Since a film having a function of being able to be used for insulating purposes is formed on the insulating film 204 and no oxygen addition treatment is performed, The result is that no indium is implanted into the film 204, or the amount of indium implanted is very small. It suggests.

[0058] As described above, a film capable of suppressing oxygen release is formed on an insulating film, and the insulating film is then When oxygen is introduced into the insulating film, the constituent elements of the film that have the function of suppressing the release of oxygen are Indium, which is a fluorine atom, is implanted into the insulating film.

[0059] In the semiconductor device of one embodiment of the present invention, the insulating films 114 and 1 Then, a film having a function of suppressing oxygen release is formed on the insulating film 116. By supplying oxygen to the insulating films 114 and 116 through the insulating film, The insulating films 114 and 116 may contain excess oxygen. The oxygen compensates for oxygen vacancies formed in the oxide semiconductor film 108. By filling in the oxygen vacancies in the silicon substrate, a highly reliable semiconductor device can be provided. Cut.

[0060] Other components included in the semiconductor device of this embodiment will be described in detail below. do.

[0061] <Substrate> There is no particular restriction on the material of the substrate 102, but it should be strong enough to withstand the subsequent heat treatment. For example, glass substrates, ceramic substrates, quartz substrates, and sa A fire substrate or the like may be used as the substrate 102. Also, a material such as silicon or silicon carbide may be used. Single crystal semiconductor substrates, polycrystalline semiconductor substrates, compound semiconductors such as silicon germanium, etc. It is also possible to use a substrate, an SOI substrate, or the like, on which a semiconductor element is provided. The substrate 102 may be a glass substrate. If you have 6th generation (1500mm x 1850mm), 7th generation (1870mm x 220 0mm), 8th generation (2200mm x 2400mm), 9th generation (2400mm x 280 By using large-area substrates such as 10th generation (2950mm x 3400mm), Larger display devices can be manufactured.

[0062] In addition, a flexible substrate is used as the substrate 102, and the transistor 10 is directly formed on the flexible substrate. Alternatively, a peeling layer may be provided between the substrate 102 and the transistor 100. The release layer is preferably removed from the substrate 102 after a semiconductor device is partially or entirely completed thereon. The transistor 100 can be separated and used for transfer to another substrate. It can also be transferred to substrates with poor thermal properties or flexible substrates.

[0063] <Conductive film> A conductive film 104 serving as a first gate electrode and a conductive film 105 serving as a source electrode and a drain electrode are formed. The conductive films 112a and 112b that function as a conductive film are made of chromium (Cr), copper (Cu), aluminum (Al), or the like. Aluminum (Al), Gold (Au), Silver (Ag), Zinc (Zn), Molybdenum (Mo), Tantalum (Ta), titanium (Ti), tungsten (W), manganese (Mn), nickel (Ni) , iron (Fe), cobalt (Co), or a metal element selected from the above metal elements. The alloy may be formed by using an alloy of the above-mentioned metal elements or an alloy combining the above-mentioned metal elements. can.

[0064] The conductive films 104, 112a, and 112b may have a single-layer structure or a laminated structure of two or more layers. For example, a single layer structure of an aluminum film containing silicon, titanium on an aluminum film, A two-layer structure in which a titanium film is laminated on a titanium nitride film, a two-layer structure in which a titanium film is laminated on a titanium nitride film, a titanium nitride film A two-layer structure in which a tungsten film is laminated on top of a tantalum nitride film or a tungsten nitride film A two-layer structure in which a tungsten film is laminated, a titanium film, and an aluminum film is laminated on the titanium film. There are three-layer structures, such as a titanium film on top of an aluminum film. Select from tantalum, tungsten, molybdenum, chromium, neodymium, and scandium. Alternatively, an alloy film or a nitride film made by combining one or more of these may be used.

[0065] The conductive films 104, 112a, and 112b are made of indium tin oxide or tungsten oxide. Indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, titanium oxide Indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium zinc oxide A conductive material having light transmitting properties, such as indium tin oxide doped with silicon oxide, is used. It is also possible.

[0066] The conductive films 104, 112a, and 112b are made of a Cu-X alloy film (X is Mn, Ni, Cr, Fe, Co, Mo, Ta, or Ti) may be applied. This allows processing using a wet etching process, which reduces manufacturing costs. It becomes possible.

[0067] <Gate insulating film> The insulating films 106 and 107 functioning as the first gate insulating film of the transistor 100 are Plasma Enhanced Chemical Vapor Deposition (PECVD) Oxidation is performed by the ical vapor deposition (CVD) method, sputtering method, etc. Silicon film, silicon oxynitride film, silicon oxynitride film, silicon nitride film, aluminum oxide hafnium oxide film, yttrium oxide film, zirconium oxide film, gallium oxide film , tantalum oxide film, magnesium oxide film, lanthanum oxide film, cerium oxide film and ne oxide film The insulating film 106 and the insulating layer 107 may each include an insulating layer containing one or more oxynitride films. Instead of the laminated structure of 107, a single insulating film selected from the above-mentioned materials or three or more insulating films may be used. An insulating film may also be used.

[0068] Note that the oxide semiconductor film 108 functioning as a channel region of the transistor 100 The insulating film 107 is preferably an oxide insulating film, and has an oxide content in excess of the stoichiometric composition. It is more preferable that the insulating film 1 has a region containing oxygen (an oxygen excess region). The insulating film 107 is capable of releasing oxygen. In order to provide the insulating film 107, for example, the insulating film 107 may be formed in an oxygen atmosphere. Oxygen may be introduced into the insulating film 107 to form an oxygen excess region. These include ion implantation, ion doping, plasma immersion ion implantation, and plasma Zuma processing or the like can be used.

[0069] When hafnium oxide is used as the insulating film 107, the following effects are obtained. Hafnium has a higher dielectric constant than silicon oxide and silicon oxynitride. Compared to the case where silicon oxide is used, the thickness of the insulating film 107 can be made larger, so that the tunnel This reduces the leakage current caused by the current. Furthermore, hafnium oxide, which has a crystalline structure, can be used to realize an amorphous structure. It has a higher relative dielectric constant than hafnium oxide, which has a low off-current. To form a transistor, it is preferable to use hafnium oxide having a crystalline structure. Examples of the crystal structure include monoclinic and cubic. The types are not limited to these.

[0070] In this embodiment, a silicon nitride film is formed as the insulating film 106, and the insulating film 107 is The silicon oxide film is formed as a result of the above. The silicon nitride film has a lower dielectric constant than the silicon oxide film. The film thickness required to obtain the same capacitance as a silicon oxide film is large, so it is suitable for transistors. The gate insulating film of the transistor 100 is made physically thick by including a silicon nitride film. Therefore, the decrease in the dielectric strength of the transistor 100 can be suppressed, and the dielectric strength can be improved. The edge breakdown voltage can be improved and electrostatic breakdown of the transistor 100 can be suppressed.

[0071] <Oxide semiconductor film> The oxide semiconductor film 108 is made of oxygen, In, Zn, and M (M is Ti, Ga, Sn, Y). , Zr, La, Ce, Nd, or Hf). 8 can be In-Ga oxide, In-Zn oxide, or In-M-Zn oxide. In particular, it is preferable to use In-M-Zn oxide as the oxide semiconductor film 108. .

[0072] In the case where the oxide semiconductor film 108 is an In-M-Zn oxide, the In-M-Zn oxide is formed. The atomic ratio of the metal elements in the sputtering target used for this purpose is In≧M, Zn≧M. It is preferable that the atomic ratio of the metal elements in such a sputtering target and In:M:Zn=1:1:1, In:M:Zn=1:1:1.2, In:M:Zn = 2:1:3, In:M:Zn = 3:1:2, In:M:Zn = 4:2:4.1 are preferred. Note that the atomic ratio of the oxide semiconductor film 108 to be formed is calculated by subtracting the above-mentioned steps from the atomic ratio of the oxide semiconductor film 108 as an error. The atomic ratio of metal elements contained in the sputtering target can vary by ±40%. For example, a sputtering target with an atomic ratio of In:Ga:Zn=4:2 When the In:Ga:Z oxide semiconductor film 108 is formed using the In:Ga:Z oxide semiconductor film 108, the atomic ratio of the In:Ga:Z oxide semiconductor film 108 is 1:1. In some cases, the n ratio is around 4:2:3.

[0073] When the oxide semiconductor film 108 is an In-M-Zn oxide, the The atomic ratio of In and M is preferably higher than 25 atomic % and higher than 75 atomic %. More preferably, In is less than 34 atomic %, and M is 66 atomic %. Less than omic percent.

[0074] The oxide semiconductor film 108 has an energy gap of 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. By using a nitride semiconductor, the off-state current of the transistor 100 can be reduced.

[0075] The thickness of the oxide semiconductor film 108 is greater than or equal to 3 nm and less than or equal to 200 nm, preferably less than or equal to 3 nm. The thickness is set to 100 nm or more, and more preferably 3 nm or more and 50 nm or less.

[0076] In addition, as the oxide semiconductor film 108, an oxide semiconductor film with low carrier density is used. For example, the oxide semiconductor film 108 has a carrier density of 1×10 17 pieces / cm 3 The following is preferred: 1×10 15 pieces / cm 3 Less than 1×10, more preferably 13 pieces / cm 3 More details below. Preferably 1 x 10 11 pieces / cm 3 The following applies.

[0077] In addition, the semiconductor characteristics and electrical characteristics (field effect) of the required transistors are not limited to these. It is sufficient to use a material with an appropriate composition according to the required properties (e.g., the resultant mobility, threshold voltage, etc.). In order to obtain semiconductor characteristics of a transistor, the carrier density and impurity of the oxide semiconductor film 108 are The concentration of metals, defect density, atomic ratio of metal elements to oxygen, interatomic distance, density, etc. are appropriately adjusted. It is preferable.

[0078] Note that the oxide semiconductor film 108 is an oxide semiconductor having a low impurity concentration and a low density of defect states. By using a conductive film, it is possible to fabricate a transistor with even better electrical characteristics. Here, it is preferable that the impurity concentration is low and the defect level density is low (there is little oxygen vacancy). High purity authentic or substantially high purity authentic. High purity authentic or substantially high purity authentic Since the oxide semiconductor film has a small number of carrier generation sources, the carrier density can be reduced. Therefore, a transistor in which a channel region is formed in the oxide semiconductor film can have a threshold voltage of 100 V. The electrical characteristics where the voltage is negative (also called normally on) are rare. In addition, a highly-purified intrinsic or substantially highly-purified intrinsic oxide semiconductor film has a low density of defect states. Therefore, the trap density may be low. The intrinsic oxide semiconductor film has a significantly small off-state current and a channel width W of 1×10 6 μm Even if the channel length L of the element is 10 μm, the voltage between the source electrode and the drain electrode (drain The off-state current is measured at a voltage between 1V and 10V. below the measurement limit, i.e. 1×10 -13 It is possible to obtain a characteristic of A or less.

[0079] Therefore, the high-purity intrinsic or substantially high-purity intrinsic oxide semiconductor film is provided with a channel. The transistors in which the regions are formed have small variations in electrical characteristics and are highly reliable. Note that charges trapped in the trap states of the oxide semiconductor film are dissipated. It takes a long time for the charge to reach a certain level, and it may behave as if it were a fixed charge. A transistor in which a channel region is formed in an oxide semiconductor film with a high density of trap states has a high current density. Impurities include hydrogen, nitrogen, alkali metals, or Alkaline earth metals, etc.

[0080] Hydrogen contained in the oxide semiconductor film 108 reacts with oxygen that is bonded to metal atoms to become water. At the same time, oxygen vacancies are formed in the lattice from which oxygen has been removed (or in the portion from which oxygen has been removed). When hydrogen enters an electron vacancy, a carrier can be generated. Some of them may combine with oxygen, which bonds with metal atoms, to generate electrons that act as carriers. Therefore, a transistor using an oxide semiconductor film containing hydrogen has a normally-on characteristic. For this reason, it is necessary to reduce hydrogen as much as possible in the oxide semiconductor film 108. Specifically, in the oxide semiconductor film 108, Hydrogen concentration is 2×10 20 atoms / cm 3 Less than or equal to 5×10 19 atoms / cm 3 Less than or equal to 1×10 19 atoms / cm 3 Less than or equal to 5, more preferably ×10 18 atoms / cm 3 Less than or equal to 1×10 18 atoms / cm 3 Below or less, more preferably 5×10 17 atoms / cm 3 Less than 1×10, more preferably 1 6 atoms / cm 3 The following applies.

[0081] The oxide semiconductor film 108 contains silicon or carbon, which is one of Group 14 elements. As a result, oxygen vacancies increase in the oxide semiconductor film 108, causing the oxide semiconductor film 108 to become n-type. The concentration of silicon and carbon in the nitride semiconductor film 108 and the concentration of silicon and carbon in the oxide semiconductor film 108 near the interface The concentration of silicon and carbon in the vicinity (obtained by SIMS analysis) was 2×10 18 ato ms / cm 3 Less than or equal to 2 x 10 17 atoms / cm 3 The following applies.

[0082] In addition, in the oxide semiconductor film 108, an alkali metal or is the concentration of alkaline earth metals, 1×10 18 atoms / cm 3 Below, preferably 2 x 1 0 16 atoms / cm 3 Alkali metals and alkaline earth metals are oxide semiconductors. When it bonds with a conductor, it can generate carriers, which increases the off-state current of the transistor. For this reason, the alkali metal or alkaline earth metal of the oxide semiconductor film 108 It is preferable to reduce the concentration of the genus.

[0083] When the oxide semiconductor film 108 contains nitrogen, electrons that serve as carriers are generated, and The carrier density increases and the oxide semiconductor film containing nitrogen is easily converted to n-type. The transistor using this oxide semiconductor film tends to be normally on. In this case, it is preferable that the nitrogen content is reduced as much as possible. For example, The nitrogen concentration is 5×1018 atoms / cm 3 It is preferable to do the following:

[0084] The oxide semiconductor film 108 may have a non-single crystal structure, for example. For example, CAAC-OS (C Axis Aligned Crystalline Oxide Semiconductor), polycrystalline structure, microcrystalline structure (described later), Among non-single crystal structures, the amorphous structure has the highest defect level density, C AAC-OS has the lowest defect state density.

[0085] The oxide semiconductor film 108 may have an amorphous structure, for example. For example, the atomic arrangement is disordered and has no crystalline components. Or, an oxide with an amorphous structure The film, for example, has a completely amorphous structure and does not have any crystalline portions.

[0086] Note that the oxide semiconductor film 108 may have an amorphous structure, a microcrystalline structure, or a polycrystalline structure. A mixed film having two or more of the following regions may be used: a region of a CAAC-OS structure, a region of a single crystal structure, and a region of a crystalline structure. The mixed film may have, for example, an amorphous structure region, a microcrystalline structure region, a polycrystalline structure region, a CA In the case of a single-layer structure having two or more regions of either AC-OS or single crystal structure In addition, the mixed film may have, for example, an amorphous structure region, a microcrystalline structure region, a polycrystalline structure region, and the like. A laminate having two or more of the following regions: a CAAC-OS region, a single crystal structure region, and a It may have a structure.

[0087] <Protective insulating film> The insulating films 114, 116, and 118 function as protective insulating films. The insulating film 116 contains oxygen. The insulating film 114 is an insulating film that can transmit oxygen. The insulating film 114 is formed by using an oxide semiconductor when the insulating film 116 is formed later. It also functions as a film for reducing damage to the film 108 .

[0088] The insulating film 114 has a thickness of 5 nm to 150 nm, preferably 5 nm to 50 nm. Silicon oxide, silicon oxynitride, etc., having a thickness of 1 nm or less can be used.

[0089] In addition, it is preferable that the insulating film 114 has a small number of defects. (ESR) measurements reveal that the g value is 2.001, which is due to the dangling bond of silicon. The spin density of the signal is 3×10 17 spins / cm 3 It is preferable that the following is true: If the insulating film 114 contains a large number of defects, oxygen will bond to the defects, causing the insulating film The amount of oxygen permeating through 114 decreases.

[0090] In the insulating film 114, all of the oxygen that has entered the insulating film 114 from the outside is Some oxygen does not move to the outside of the insulating film 114 and remains in the insulating film 114. At the same time, oxygen contained in the insulating film 114 moves to the outside of the insulating film 114, In some cases, oxygen may move through the film 114. When the oxide insulating film capable of forming the insulating film 116 is formed over the insulating film 114, The desorbed oxygen can be transferred to the oxide semiconductor film 108 through the insulating film 114. .

[0091] The insulating film 114 is formed using an oxide insulating film having a low density of states caused by nitrogen oxides. Note that the density of states caused by the nitrogen oxides can be calculated by the valence charge of the oxide semiconductor film. Energy at the top of the nucleus (E v_os ) and the conduction band minimum of the oxide semiconductor film ( E c_os As the oxide insulating film, a nitrogen oxide film may be formed between the insulating film and the insulating film. Silicon oxynitride film with low emission or aluminum oxynitride film with low emission of nitrogen oxides A film such as a gypsum film can be used.

[0092] In addition, the silicon oxynitride film, which emits a small amount of nitrogen oxide, is found to have a low nitrogen oxide emission rate in TDS. This is a membrane that releases more ammonia than other substances. ×10 18 pieces / cm 3 5×10 or more 19 pieces / cm 3 The following is the release of ammonia. The amount is adjusted so that the surface temperature of the film is 50°C or higher and 650°C or lower, preferably 50°C or higher and 550°C or lower. This is the amount released due to heat treatment.

[0093] Nitrogen oxides (NO x , x is 0 or more and 2 or less, preferably 1 or more and 2 or less), typically NO 2 or NO forms a level in the insulating film 114 or the like. 8. Therefore, the nitrogen oxide is in the insulating film 114 and the oxide When the charge-discharge level diffuses to the interface of the semiconductor film 108, the charge-discharge level traps electrons on the insulating film 114 side. As a result, the trapped electrons may wrap around the insulating film 114 and the oxide semiconductor. Since the ions remain near the interface with the semiconductor film 108, the threshold voltage of the transistor is shifted in the positive direction. It will cause.

[0094] Nitrogen oxide reacts with ammonia and oxygen during heat treatment. The nitrogen oxide contained in the insulating film 116 reacts with ammonia contained in the insulating film 116 during the heat treatment. Therefore, the amount of nitrogen oxide contained in the insulating film 114 is reduced. In this case, electrons are less likely to be trapped in the vicinity of the interface between the oxide semiconductor film 106 and the oxide semiconductor film 108.

[0095] By using the above oxide insulating film for the insulating film 114, the threshold voltage of the transistor can be shifted. It is possible to reduce the fluctuation of the electrical characteristics of the transistor. do.

[0096] Heat treatment in the manufacturing process of a transistor is typically performed at a temperature of 300° C. or higher but below the substrate distortion point. The insulating film 114 is heated to a temperature of 100 K or lower. The first signal has a g value of 2.037 to 2.039, and the second signal has a g value of 2.001 or more. The second signal is less than or equal to 2.003, and the third signal is greater than or equal to 1.964 and less than or equal to 1.966. The split width of the first signal and the second signal, The split width of the second and third signals is approximately 1.0 mm in the X-band ESR measurement. 5mT. The first signal has a g value of 2.037 to 2.039, and the second signal has a g value of 2. A second signal between 0.001 and 2.003, and a g value between 1.964 and 1.966 The sum of the spin densities of the third signal is 1 × 10 18 spins / cm 3 Less than Typically, it is 1×10 17 spins / cm 3 More than 1×10 18 spins / cm 3 Not yet It is full.

[0097] In addition, the g value in the ESR spectrum below 100K is 2.037 to 2.039. The first signal has a g value of 2.001 to 2.003, and the second signal has a g value of 1 The third signal, between .964 and 1.966, is nitrogen oxide (NO x , x is 0 to 2 Representative examples of nitrogen oxides include: , nitrogen monoxide, nitrogen dioxide, etc. That is, the first group with a g value of 2.037 to 2.039. A signal with a g-value between 2.001 and 2.003, and a second signal with a g-value between 1.96 and 2.003. The smaller the sum of the spin densities of the third signals, which is greater than or equal to 4 and less than or equal to 1.966, the more likely the oxide is to have a high spin density. It can be said that the content of nitrogen oxides in the insulating film is small.

[0098] The oxide insulating film has a nitrogen concentration of 6×10 20 ato ms / cm 3 The following is the result.

[0099] The substrate temperature is 220°C or higher, 280°C or higher, or 350°C or higher, and silane and The oxide insulating film is formed by using the PECVD method with nitrous oxide and nitric oxide. A film that is dense and has high hardness can be formed.

[0100] The insulating film 116 is an oxide insulating film containing more oxygen than the oxygen required for the stoichiometric composition. The oxide insulating film containing more oxygen than the stoichiometric composition is formed using When heated, some of the oxygen is released. The oxygen content is greater than the stoichiometric composition. The oxide insulating film had a release of oxygen of 1.0×10 in terms of oxygen atoms as determined by TDS analysis. 1 9atoms / cm 3 More than 3.0×10 20 atoms / cm 3 That's all. The oxide insulating film is a thin film. The surface temperature of the film during the TDS analysis was 100°C or less. The range is preferably from 100° C. to 500° C. or from 100° C. to 500° C.

[0101] The insulating film 116 has a thickness of 30 nm to 500 nm, preferably 50 nm or more. Silicon oxide, silicon oxynitride, etc., having a thickness of 400 nm or less can be used.

[0102] In addition, it is preferable that the insulating film 116 has a small amount of defects. The spin density of the signal at g=2.001 originating from the silicon dangling bond is 1.5 x 10 18 spins / cm 3 Less than or even 1×10 18 spins / cm 3 Note that the insulating film 116 is preferably an oxide semiconductor compared to the insulating film 114. Since it is separated from the insulating film 108, it may have a higher defect density than the insulating film 114.

[0103] Indium is also detected near the surface of the insulating film 116 .

[0104] In addition, the insulating films 114 and 116 can be made of the same material, so that the insulating films In some cases, the interface between the film 114 and the insulating film 116 cannot be clearly seen. In this embodiment, the interface between the insulating film 114 and the insulating film 116 is shown by a dashed line. In the embodiment, the two-layer structure of the insulating film 114 and the insulating film 116 has been described. For example, the insulating film 114 may have a single-layer structure without being limited thereto.

[0105] The insulating film 118 contains nitrogen. The insulating film 118 also contains nitrogen and silicon. The insulating film 118 is also formed of blockers such as oxygen, hydrogen, water, alkali metals, and alkaline earth metals. By providing the insulating film 118, the oxide semiconductor film 108 can prevent the oxidation of the oxide semiconductor film 108. The diffusion of oxygen contained in the insulating films 114 and 116 to the outside, and the diffusion of oxygen from the outside This can prevent hydrogen, water, and the like from entering the oxide semiconductor film 108. For example, a nitride insulating film can be used. Silicon nitride oxide, aluminum nitride, aluminum oxide nitride, etc. A nitride insulator that has a blocking effect against nitrogen, hydrogen, water, alkali metals, alkaline earth metals, etc. Instead of the insulating film, an oxide insulating film having a blocking effect against oxygen, hydrogen, water, etc. may be provided. As an oxide insulating film having a blocking effect against oxygen, hydrogen, water, and the like, aluminum oxide is used. nium, aluminum oxide nitride, gallium oxide, gallium oxide nitride, yttrium oxide, Examples include yttrium oxynitride, hafnium oxide, and hafnium oxynitride.

[0106] Note that the various films described above, such as the conductive film, the insulating film, and the oxide semiconductor film, are formed by sputtering. It can be formed by the CVD method or PECVD method, but other methods such as thermal CVD (Ch Alternatively, the insulating layer may be formed by thermal CVD. As an example of the method, MOCVD (Metal Organic Chemical Vapor Deposition) The deposition method may also be used.

[0107] Thermal CVD is a film formation method that does not use plasma, so defects can occur due to plasma damage. This has the advantage that no additional steps are required.

[0108] In the thermal CVD method, the source gas and the oxidizing agent are fed into the chamber at the same time, and the chamber is heated to atmospheric pressure. Alternatively, a film is formed by reacting the reactants near or on the substrate under reduced pressure and depositing the reactants on the substrate. You may go.

[0109] In addition, in the ALD method, the pressure inside the chamber is set at atmospheric pressure or reduced pressure, and the source gas for the reaction is The gases may be introduced into the chamber in sequence, and the film may be formed by repeating the gas introduction sequence. For example, by switching each switching valve (also called high-speed valve), two or more types of The above source gases are supplied to the chamber in order, and the first source gas is supplied to the chamber in order to prevent the mixture of the source gases. An inert gas (such as argon or nitrogen) is introduced simultaneously with or after the raw material gas. The second source gas is introduced. When an inert gas is introduced at the same time, the inert gas is It acts as a carrier gas, and even if an inert gas is introduced at the same time as the second source gas is introduced, In addition, the first source gas is discharged by evacuation instead of introducing an inert gas. After that, a second source gas may be introduced. The first source gas is adsorbed on the surface of the substrate to form a first layer. The first layer is deposited on the second layer by reacting with the second source gas introduced later. This process is repeated several times while controlling the gas introduction sequence until the desired thickness is reached. By doing so, a thin film with excellent step coverage can be formed. The thickness of the thin film is determined by the gas introduction. The thickness can be precisely adjusted by changing the number of times the sequence is repeated. This is suitable for producing miniature FETs.

[0110] Thermal CVD methods such as MOCVD can be used to form the conductive film, insulating film, oxide semiconductor film, It is possible to form various films such as metal oxide films. For example, an In-Ga-ZnO film can be formed. In this case, trimethylindium, trimethylgallium, and dimethylzinc are used. The chemical formula for trimethylindium is In(CH3)3. The chemical formula for gallium is Ga(CH3)3. The chemical formula for dimethylzinc is Zn( CH3)2. In addition, the combination is not limited to these, and instead of trimethylgallium, Alternatively, triethylgallium (chemical formula Ga(C2H5)3) can be used, and dimethylzinc Alternatively, diethylzinc (chemical formula Zn(C2H5)2) can be used.

[0111] For example, when forming a hafnium oxide film using a film forming apparatus that uses ALD, the solvent and liquids containing hafnium precursor compounds (hafnium alkoxides, tetrakisdimethyl The raw material gas is made by vaporizing hafnium amide (such as TDMAH) and acid. Two types of gases are used: tetrakisdimethylamide (TDA) and ozone (O3). The chemical formula for fluorine is Hf[N(CH3)2]4. Other liquid materials include tetrahydrofuran. Examples include rakis(ethylmethylamido)hafnium.

[0112] For example, when forming an aluminum oxide film using an ALD deposition system, A liquid containing a catalyst and an aluminum precursor compound (e.g., trimethylaluminum (TMA)) is added. Two types of gases are used: vaporized source gas and H2O as an oxidizing agent. The chemical formula for aluminum is Al(CH3)3. Other liquid materials include Tris( Dimethylamido)aluminum, triisobutylaluminum, aluminum tris(2 ,2,6,6-tetramethyl-3,5-heptanedionate).

[0113] For example, when forming a silicon oxide film using a deposition system that uses ALD, Chlorodisilane is adsorbed onto the surface to be coated, the chlorine contained in the adsorbed matter is removed, and the oxidizing gas (O 2. Nitrous oxide (NO) radicals are supplied to react with the adsorbed material.

[0114] For example, when forming a tungsten film using an ALD deposition system, WF6 The initial tungsten film was formed by repeatedly introducing B2H6 gas and WF The tungsten film is formed by repeatedly introducing B2H6 gas and H2 gas in sequence. Alternatively, SiH4 gas may be used instead of gas.

[0115] For example, an oxide semiconductor film, such as In-Ga-ZnO, can be formed by a film formation apparatus using ALD. When forming a film, In(CH3)3 gas and O3 gas are introduced in sequence and repeatedly to form InO Then, Ga(CH3)3 gas and O3 gas are repeatedly introduced to form a GaO layer. Then, Zn(CH3)2 gas and O3 gas are repeatedly introduced to form a ZnO layer. The order of these layers is not limited to this example. Mixed compound layers such as In-Ga-O, In-Zn-O, and Ga-Zn-O layers are formed. It is also possible to use H2O gas obtained by bubbling an inert gas such as Ar instead of O3 gas. However, it is preferable to use O3 gas that does not contain H. In(CH3 Instead of In(C2H5)3 gas, Ga(CH3)3 gas may be used. Instead of gas, Ga(C2H5)3 gas may be used. Also, Zn(CH3)2 gas may be used. It's fine if you're there.

[0116] <Configuration Example 2 of Semiconductor Device> Next, examples of a configuration different from that of the transistor 100 shown in FIGS. The following will be explained using 4(A), (B), and (C). Note that the functions described above are the same as those described above. In some cases, the hatch patterns may be the same and no particular reference numbers may be used.

[0117] FIG. 4A is a top view of a transistor 150 which is a semiconductor device of one embodiment of the present invention. 4B corresponds to a cross-sectional view taken along the dashed line X1-X2 in FIG. 4A. FIG. 4(C) is a cross-sectional view taken along the dashed line Y1-Y2 in FIG. 4(A). Correct.

[0118] The transistor 150 includes a conductive film 104 over a substrate 102, the conductive film 104 serving as a first gate electrode. an insulating film 106 on the substrate 102 and the conductive film 104; and an insulating film 107 on the insulating film 106. , an oxide semiconductor film 108 on the insulating film 107, and an insulating film 114 on the oxide semiconductor film 108. , an insulating film 116 on the insulating film 114, and openings provided in the insulating film 114 and the insulating film 116 The electrode 141 functions as a source electrode electrically connected to the oxide semiconductor film 108 through the insulating film 141a. Through the conductive film 112a and the opening 141b provided in the insulating film 114 and the insulating film 116, A conductive film 112b functioning as a drain electrode electrically connected to the oxide semiconductor film 108. In addition, the transistor 150, more specifically, the conductive films 112a and 112b An insulating film 118 is provided on the insulating film 114 and the insulating film 116. The insulating film 118 functions as a protective insulating film for the oxide semiconductor film 108. It functions as a protective insulating film for the gate 150.

[0119] In addition, the transistor 150 has indium in the vicinity of the interface between the insulating film 116 and the insulating film 118. has.

[0120] The transistor 100 shown above has a channel etch structure. The transistor 150 shown in FIGS. 4A, 4B, and 4C has a channel protection type structure. As described above, the semiconductor device according to one embodiment of the present invention can be used as both a channel etch type and a channel protection type. The present invention can be applied to the above transistor structures.

[0121] The transistor 150 is a transistor including an oxide semiconductor film, similar to the transistor 100 described above. Since the insulating films 114 and 116 are provided on the insulating film 108, The oxygen contained in the oxide semiconductor film 108 can compensate for oxygen vacancies in the oxide semiconductor film 108.

[0122] <Configuration Example 3 of Semiconductor Device> Next, a configuration example different from that of the transistor 150 shown in FIGS. 5(A), (B), and (C) will be used. Note that the functions described above are the same as those described above. In some cases, the hatch patterns may be the same and no particular reference numbers may be used.

[0123] FIG. 5A is a top view of a transistor 160 which is a semiconductor device of one embodiment of the present invention. 5B corresponds to a cross-sectional view taken along dashed line X1-X2 in FIG. 5A. FIG. 5(C) is a cross-sectional view taken along the dashed line Y1-Y2 in FIG. 5(A). Correct.

[0124] The transistor 160 includes a conductive film 104 over a substrate 102, the conductive film 104 serving as a first gate electrode. an insulating film 106 on the substrate 102 and the conductive film 104; and an insulating film 107 on the insulating film 106. , an oxide semiconductor film 108 on the insulating film 107, and an insulating film 114 on the oxide semiconductor film 108. , an insulating film 116 on the insulating film 114, and a source The conductive film 112a serving as an electrode and the drain electrically connected to the oxide semiconductor film 108 The transistor 160 has a conductive film 112b which functions as an in-electrode. More specifically, an insulating film 118 is provided on the conductive films 112a and 112b and the insulating film 116. The insulating films 114 and 116 function as protective insulating films for the oxide semiconductor film 108. The insulating film 118 functions as a protective insulating film for the transistor 160.

[0125] In addition, the transistor 160 has indium in the vicinity of the interface between the insulating film 116 and the insulating film 118. has.

[0126] The transistor 160 is a transistor 150 and an insulating film 1 shown in FIG. Specifically, the shapes of the insulating films 114 and 116 of the transistor 160 are different. The transistor 6 is provided in an island shape on a channel region of the oxide semiconductor film 108. It is similar to the transistor 150 and has the same effect.

[0127] <Configuration Example 4 of Semiconductor Device> Next, examples of a configuration different from that of the transistor 100 shown in FIGS. The following will be explained using 6(A), (B), and (C). Note that the functions described above are the same as those described above. In some cases, the hatch patterns may be the same and no particular reference numbers may be used.

[0128] FIG. 6A is a top view of a transistor 170 which is a semiconductor device of one embodiment of the present invention. 6B corresponds to a cross-sectional view taken along the dashed line X1-X2 in FIG. 6A. FIG. 6C is a cross-sectional view taken along the dashed line Y1-Y2 in FIG. Correct.

[0129] The transistor 170 includes a conductive film 104 over a substrate 102, the conductive film 104 serving as a first gate electrode. an insulating film 106 on the substrate 102 and the conductive film 104; and an insulating film 107 on the insulating film 106. , an oxide semiconductor film 108 on the insulating film 107, and an insulating film 114 on the oxide semiconductor film 108. , an insulating film 116 on the insulating film 114, and a source The conductive film 112a serving as an electrode and the drain electrically connected to the oxide semiconductor film 108 The conductive film 112b functions as an inner electrode, and the conductive films 112a and 112b and the insulating film 116 The insulating film 118 is disposed on the upper surface of the semiconductor substrate 110, and the conductive films 120a and 120b are disposed on the insulating film 118.

[0130] In addition, the transistor 170 has indium in the vicinity of the interface between the insulating film 116 and the insulating film 118. has.

[0131] In addition, in the transistor 170, the insulating films 114, 116, and 118 The second insulating film of the transistor 170 functions as a second gate insulating film of the transistor 170. The conductive film 120a functions as, for example, a pixel electrode used in a display device. The conductive film 120a is formed through an opening 142c provided in the insulating films 114, 116, and 118. In the transistor 170, the conductive film 120b is connected to the conductive film 112b. , which functions as a second gate electrode (also called a back gate electrode).

[0132] As shown in FIG. 6C, the conductive film 120b is formed by insulating films 106, 107, 114, and 1 In the openings 142a and 142b provided in the gate electrodes 16 and 118, Therefore, the conductive film 120b and the conductive film 104 are the same. A potential is applied.

[0133] In this embodiment, openings 142a and 142b are provided, and the conductive film 120b and Although the configuration in which the conductive film 104 is connected has been illustrated, the present invention is not limited to this. Only one of the openings 142a and 142b is formed, and the conductive film 120b and The conductive film 104 is connected, or the openings 142a and 142b are not provided, and the conductive film 104 is not connected. The conductive film 120b and the conductive film 104 may not be connected to each other. In the case where the conductive film 104 is not connected, the conductive film 120b and the conductive film 104 are each provided with different It is possible to apply a voltage to the

[0134] As shown in FIG. 6B, the oxide semiconductor film 108 functions as a first gate electrode. The conductive film 104 functions as a second gate electrode, and the conductive film 120b functions as a second gate electrode. The second gate electrode is sandwiched between two conductive films that function as gate electrodes. The length in the channel length direction and the length in the channel width direction of the conductive film 120b functioning as a gate electrode are The length is larger than the length of the oxide semiconductor film 108 in the channel length direction and the length of the oxide semiconductor film 108 in the channel width direction. The oxide semiconductor film 108 is entirely conductive via the insulating films 114, 116, and 118. The conductive film 120b functions as a second gate electrode. The conductive film 104 functioning as the first gate electrode is made of insulating films 106, 107, 114, and 1 16, 118 are connected through openings 142a, 142b. The side surface of the conductor film 108 in the channel width direction is connected to the second insulating film 114, 116, and 118 via the insulating films 114, 116, and 118. It faces the conductive film 120b which functions as a gate electrode.

[0135] In other words, in the channel width direction of the transistor 170, The conductive film 104 functioning as the second gate electrode and the conductive film 120b functioning as the first gate electrode are The insulating films 106 and 107 functioning as a first gate insulating film and the insulating film 108 functioning as a second gate insulating film The insulating films 114, 116, and 118 are connected through openings, and the first gate The insulating films 106 and 107 function as first gate insulating films, and the insulating film 108 functions as a second gate insulating film. The insulating films 114, 116, and 118 surround the oxide semiconductor film 108.

[0136] With such a structure, the oxide semiconductor film 108 included in the transistor 170 The conductive film 104 functions as a first gate electrode and the conductive film 105 functions as a second gate electrode. It can be electrically surrounded by the electric field of the conductive film 120b. The electric field of the first gate electrode and the second gate electrode causes an oxide film in which a channel region is formed. The device structure of the transistor that electrically surrounds the nitride semiconductor film is called surrounded ch This can be called an annel (s-channel) structure.

[0137] Since the transistor 170 has an s-channel structure, The conductive film 104 functions as a gate insulating film, and the electric field for inducing the channel is effectively applied to the oxide semiconductor. This allows the current drive capability of the transistor 170 to be improved. It is possible to obtain high on-current characteristics. It is also possible to increase the on-current. Therefore, it is possible to miniaturize the transistor 170. The conductive film 104 functions as a first gate electrode and the conductive film 105 functions as a second gate electrode. Since the transistor 170 has a structure surrounded by the conductive film 120b, the mechanical strength of the transistor 170 is increased. It can be done.

[0138] <Configuration Example 5 of Semiconductor Device> Next, examples of a configuration different from that of the transistor 100 shown in FIGS. 7(A)(B)(C)(D) will be used. Note that the same functions as those explained above will be used. If they are provided, the hatch patterns may be the same and no particular reference numbers may be provided.

[0139] 7A and 7B are cross-sectional views of modified examples of the transistor 100 shown in FIGS. 1B and 1C. 7C and 7D are modified examples of the transistor 100 shown in FIGS. FIG.

[0140] The transistor 100A shown in FIGS. 7A and 7B is a transistor 100A shown in FIGS. The oxide semiconductor film 108 included in the capacitor 100 has a three-layer structure. The oxide semiconductor film 108 included in the transistor 100A includes an oxide semiconductor film 108a and an oxide The semiconductor layer 108 includes a nitride semiconductor film 108b and an oxide semiconductor film 108c.

[0141] The transistor 100B shown in FIG. 7C and FIG. 7D is a transistor having a structure similar to that shown in FIG. The oxide semiconductor film 108 of the capacitor 100 has a two-layer structure. The oxide semiconductor film 108 included in the transistor 100B includes an oxide semiconductor film 108a and an oxide and a nitride semiconductor film 108b.

[0142] Here, the oxide semiconductor films 108a, 108b, and 108c and the oxide semiconductor film 108b The band structure of the insulating film in contact with 108c will be described with reference to FIG.

[0143] FIG. 8A illustrates the insulating film 107, the oxide semiconductor films 108a, 108b, and 108c, and the insulating film 108. FIG. 8B is an example of a band structure in the thickness direction of a laminated structure having an insulating film 114. a stacked structure including an insulating film 107, oxide semiconductor films 108b and 108c, and an insulating film 114. The band structure is shown in FIG. 1 in the thickness direction of the structure. The conduction band of the insulating film 107, the oxide semiconductor films 108a, 108b, and 108c, and the insulating film 114 The lowest energy level (Ec) is shown.

[0144] FIG. 8A shows a case where a silicon oxide film is used as the insulating films 107 and 114, and an oxide semiconductor film is used. The metal oxide film 108a has an atomic ratio of In:Ga:Zn=1:3:2. The oxide semiconductor film 108b is formed by using a metal target. The atomic ratio of the elements was In:Ga:Zn=1:1:1. The oxide semiconductor film 108c is formed by using an oxide semiconductor film having an atomic ratio of metal elements of In: The oxide semiconductor film was formed using a metal oxide target with a Ga:Zn=1:3:2 ratio. FIG. 1 is a band diagram of the configuration.

[0145] FIG. 8B shows a case where a silicon oxide film is used as the insulating films 107 and 114, and an oxide semiconductor film is used. The metal oxide film 108b has an atomic ratio of In:Ga:Zn=1:1:1. The oxide semiconductor film 108c is formed by using a metal target. The atomic ratio of elements was In:Ga:Zn=1:3:2. FIG. 1 is a band diagram of a structure using an oxide semiconductor film.

[0146] As shown in FIGS. 8A and 8B, in the oxide semiconductor films 108a, 108b, and 108c, In other words, the energy level at the bottom of the conduction band changes smoothly. In order to have such a band structure, the oxide At the interface between the semiconductor film 108a and the oxide semiconductor film 108b or at the interface between the oxide semiconductor film 108b and the oxide semiconductor film 108c, At the interface with the oxide semiconductor film 108c, defect states such as trap centers and recombination centers are generated. Assume that there are no impurities that would form

[0147] In order to form a continuous junction in the oxide semiconductor films 108a, 108b, and 108c, Each film is deposited using a multi-chamber deposition system (sputtering system) equipped with a lock chamber. It is necessary to continuously stack the layers without exposing them to the air.

[0148] With the structure shown in FIGS. 8A and 8B, the oxide semiconductor film 108b serves as a well. In the transistor using the above-mentioned stacked structure, the channel region is formed of the oxide semiconductor film 10 It can be seen that it is formed in 8b.

[0149] Note that the interface between the oxide semiconductor film and the insulating film or the vicinity of the interface is affected by impurities or defects. By providing the oxide semiconductor films 108a and 108c, a trap state can be formed. In addition, the trap states are located away from the oxide semiconductor film 108b in which the channel region is formed. This can be done.

[0150] In addition, the energy level of the trap state is the energy level at the bottom of the conduction band of the oxide semiconductor film 108b. If the potential is lower than the energy level (Ec), electrons tend to accumulate in the trap level. When electrons accumulate in the trap level, they become a negative fixed charge, causing the transistor The threshold voltage of the trap level is shifted in the positive direction. The energy level of the oxide semiconductor film 108b is higher than the energy level (Ec) of the conduction band minimum of the oxide semiconductor film 108b. In this way, electrons are less likely to accumulate in the trap level. This makes it possible to increase the on-current of the transistor and also to reduce the field effect mobility. The degree can be increased.

[0151] In addition, in FIGS. 8A and 8B, the oxide semiconductor films 108a and 108c are The energy level of the conduction band minimum is closer to the vacuum level than that of the solid film 108b. The energy level of the conduction band minimum of the semiconductor film 108b and the energy level of the oxide semiconductor films 108a and 108c The difference between the energy level of the conduction band minimum and that of the That is, the oxide semiconductor films 108a and 108c have a refractive index of 2 eV or less, or 1 eV or less. the difference between the electron affinity of the oxide semiconductor film 108a and the electron affinity of the oxide semiconductor film 108b is 0.15 eV or more; or 0.5 eV or more and 2 eV or less, or 1 eV or less.

[0152] With such a structure, the oxide semiconductor film 108b serves as a main path for current. The oxide semiconductor films 108a and 108c function as a channel region. The oxide semiconductor film 108b is formed by using an oxide semiconductor material having one or more metal elements. Since the oxide semiconductor film 108a is an oxide semiconductor film, the interface between the oxide semiconductor film 108a and the oxide semiconductor film 108b and Alternatively, interface scattering occurs at the interface between the oxide semiconductor film 180b and the oxide semiconductor film 108c. Therefore, the movement of carriers is not hindered at the interface, and the transistor The field effect mobility of the

[0153] In addition, the oxide semiconductor films 108a and 108c function as part of a channel region. In order to prevent this, a material having sufficiently low electrical conductivity is used. 108a and 108c are the electron affinities (the difference between the vacuum level and the energy level at the bottom of the conduction band) is smaller than that of the oxide semiconductor film 108b, and the energy level of the conduction band minimum is Use a material that has a difference (band offset) with the conduction band minimum energy level of 108b In addition, the occurrence of a difference in threshold voltage depending on the magnitude of the drain voltage is suppressed. In order to suppress this, the energy levels of the conduction band minimums of the oxide semiconductor films 108a and 108c must be The energy level of the oxide semiconductor film 108b is 0.2 eV or more lower than the vacuum level. It is preferable to use a material close to the vacuum level, preferably 0.5 eV or more closer to the vacuum level.

[0154] In addition, the oxide semiconductor films 108a and 108c do not contain a spinel crystal structure. It is preferable that the oxide semiconductor films 108a and 108c have a spinel crystal structure. In the case where the spinel type crystal structure is included, the conductive film 112a, 11 In some cases, a constituent element of the oxide semiconductor film 2b may diffuse into the oxide semiconductor film 108b. When the conductive films 108a and 108c are made of CAAC-OS, which will be described later, the conductive films 112a and 11 This is preferable because it enhances the blocking properties of the constituent elements of 2b, for example, copper element.

[0155] The thicknesses of the oxide semiconductor films 108a and 108c are determined by the composition of the conductive films 112a and 112b. The insulating film has a thickness that is greater than or equal to a thickness that can prevent the insulating film from diffusing into the oxide semiconductor film 108b. The thickness of the oxide semiconductor film 108b is set to be less than the thickness at which oxygen supply from the film 114 to the oxide semiconductor film 108b is suppressed. For example, When the oxide semiconductor films 108a and 108c have a thickness of 10 nm or more, the conductive films 112a and This can prevent the constituent elements of the oxide semiconductor film 112b from diffusing into the oxide semiconductor film 108b. In addition, when the thickness of the oxide semiconductor films 108a and 108c is set to 100 nm or less, the insulating film 114 Therefore, oxygen can be effectively supplied from the oxide semiconductor film 116 to the oxide semiconductor film 108b.

[0156] When the oxide semiconductor films 108a and 108c are In-M-Zn oxides, M is Ti. , Ga, Sn, Y, Zr, La, Ce, Nd, or Hf in a higher atomic ratio than In. In this way, the energy gap of the oxide semiconductor films 108a and 108c can be increased, and the electron affinity can be improved. Therefore, the difference in electron affinity between the oxide semiconductor film 108b and the oxide semiconductor film 108c can be reduced by adjusting the composition of the element M. In addition, it may be possible to control the amount of Ti, Ga, Sn, Y, Zr, and L. a, Ce, Nd, and Hf are metal elements with strong bonding strength with oxygen, so these elements By having a higher atomic ratio than In, oxygen vacancies are less likely to occur.

[0157] When the oxide semiconductor films 108a and 108c are made of In-M-Zn oxide, Zn and The atomic ratio of In and M excluding O is preferably 50 atomic % In. less than 50 atomic %, M is more than 50 atomic %, and more preferably In is 25 atomic % In addition, the oxide semiconductor films 108a and 108c are A gallium oxide film may be used as the insulating film.

[0158] In addition, when the oxide semiconductor films 108a, 108b, and 108c are made of In-M-Zn oxide, , compared with the oxide semiconductor film 108b, M contained in the oxide semiconductor films 108a and 108c The atomic ratio of the above atoms is typically larger than that of the above atoms contained in the oxide semiconductor film 108b. The atomic ratio is 1.5 times or more, preferably 2 times or more, and more preferably 3 times or more. .

[0159] In addition, when the oxide semiconductor films 108a, 108b, and 108c are made of In-M-Zn oxide, The oxide semiconductor film 108b is In:M:Zn=x1:y1:z1 [atomic ratio], When the conductor films 108a and 108c have an atomic ratio of In:M:Zn=x2:y2:z2, y2 / x2 should be greater than y1 / x1, and preferably y2 / x2 should be greater than y1 / x1 by 1. More preferably, y2 / x2 is at least 2 times larger than y1 / x1, and More preferably, y2 / x2 is greater than y1 / x1 by 3 or 4 times. In the oxide semiconductor film 108b, when y1 is equal to or larger than x1, the oxide semiconductor film 108b It is preferable because it can give stable electrical characteristics to a transistor using y1. When the value is three times or more of 1, the field-effect mobility of the transistor including the oxide semiconductor film 108b is Therefore, it is preferable that y1 is less than three times x1.

[0160] When the oxide semiconductor film 108b is an In-M-Zn oxide, the oxide semiconductor film 108b is formed. The atomic ratio of the metal elements in the target used for forming the film was In:M:Zn=x1: If y1:z1, 、 x1 / y1 is 1 / 3 or more and 6 or less, and more preferably 1 or more and 6 or less. , z1 / y1 is preferably 1 / 3 or more and 6 or less, and more preferably 1 or more and 6 or less. When z1 / y1 is 1 or more and 6 or less, the oxide semiconductor film 108b can be formed by the CAA The atomic ratio of the target metal elements is typically I n:M:Zn=1:1:1, In:M:Zn=1:1:1.2, In:M:Zn=3:1 :There are 2nd and 3rd place.

[0161] In addition, when the oxide semiconductor films 108a and 108c are made of an In-M-Zn oxide, In the target used for forming the solid films 108a and 108c, the number of atoms of the metal element is If the ratio is In:M:Zn=x2:y2:z2, 、 x2 / y2 <x1 / y1であって、z 2 / y2 is preferably 1 / 3 or more and 6 or less, and more preferably 1 or more and 6 or less. By increasing the atomic ratio of M to indium, the oxide semiconductor films 108a and 108 Since it is possible to increase the energy gap of y2 and reduce the electron affinity, It is preferable that / x2 is 3 or more, or 4 or more. Representative examples are In:M:Zn=1:3:2, In:M:Zn=1:3:4, In: M:Zn=1:3:5, In:M:Zn=1:3:6, In:M:Zn=1:4:2, I n:M:Zn=1:4:4, In:M:Zn=1:4:5, In:M:Zn=1:5:5 etc.

[0162] In addition, when the oxide semiconductor films 108a and 108c are made of an In-M oxide, M is divalent gold. By making the composition free of atomic elements (e.g., zinc), it has a spinel-type crystal structure. In addition, the oxide semiconductor films 108a and 108c can be formed without using the oxide semiconductor The films 108a and 108c may be, for example, In-Ga oxide films. As the In-Ga oxide film, for example, an In-Ga metal oxide target (In:Ga= 7:93) by sputtering. In order to form the solid films 108a and 108c by a sputtering method using DC discharge, When n:M=x:y [atomic number ratio], y / (x+y) is 0.96 or less, preferably It is recommended to set it to 0.95 or less, for example 0.93.

[0163] Note that the atomic ratios of the oxide semiconductor films 108a, 108b, and 108c are each determined with an error. The atomic ratios listed above may vary by ±40%.

[0164] In addition, the transistor according to the present embodiment can be freely combined with each of the above structures. It is possible.

[0165] <Method 1 for manufacturing semiconductor device> Next, a method for manufacturing the transistor 100 illustrated in FIG. 1 which is a semiconductor device of one embodiment of the present invention will be described. This will be described in detail below with reference to FIG. 9 and FIG.

[0166] Note that the films constituting the transistor 100 (the insulating film, the oxide semiconductor film, the conductive film, and the like) are Sputtering, Chemical Vapor Deposition (CVD), Vacuum Evaporation, Pulsed Laser Deposition (PLD) Alternatively, it can be formed by a coating method or a printing method. The most common deposition methods are sputtering and plasma enhanced chemical vapor deposition (PECVD). However, thermal CVD may also be used. An example of a thermal CVD method is MOCVD (metal organic chemical vapor deposition). The multiplication method may also be used.

[0167] In the thermal CVD method, the pressure in the chamber is set to atmospheric pressure or reduced pressure, and the source gas and the oxidizing agent are simultaneously The reaction is carried out in the chamber near or on the substrate, where it is deposited on the substrate to form a film. As described above, the thermal CVD method is a film formation method that does not generate plasma. This has the advantage that defects are not generated due to damage.

[0168] In addition, in the ALD method, the pressure inside the chamber is set at atmospheric pressure or reduced pressure, and the source gas for the reaction is The gases are introduced into the chamber in sequence, and the film is formed by repeating the gas introduction sequence. For example, By switching each switching valve (also called high-speed valve), two or more types of raw materials can be The source gases are sequentially supplied to the chamber, and the first source gas is supplied to the chamber so that multiple source gases do not mix. Simultaneously with or after the second gas, an inert gas (such as argon or nitrogen) is introduced. Introduce the raw material gas. If an inert gas is introduced at the same time, the inert gas is used as a carrier gas. In addition, an inert gas may be introduced at the same time as the second source gas is introduced. Also, instead of introducing an inert gas, the first source gas is discharged by evacuation, and then the second source gas is introduced. The first source gas may be adsorbed on the surface of the substrate to form a first monoatomic layer. The second monoatomic layer is formed by reacting with the second source gas introduced later. Layer upon layer is laminated to form a thin film.

[0169] This gas introduction sequence is controlled and repeated several times until the desired thickness is achieved. The thickness of the thin film increases depending on the number of times the gas introduction sequence is repeated. This allows precise film thickness control, making it possible to fabricate minute transistors. It is suitable for fabrication.

[0170] First, a conductive film is formed on the substrate 102, and the conductive film is then subjected to a lithography process and an etching process. Then, a conductive film 104 that functions as a first gate electrode is formed by carrying out a process. On the conductive film 104, insulating films 106 and 107 that function as a first gate insulating film are formed (see FIG. 9(A)).

[0171] The conductive film 104 functioning as the first gate electrode is formed by a method such as sputtering, chemical vapor deposition ( It can be formed using the CVD method, the vacuum evaporation method, the pulsed laser deposition (PLD) method, etc. Alternatively, it can be formed by a coating method or a printing method. The most representative methods are the plasma enhanced chemical vapor deposition (PECVD) method, but the previously explained organic metal Thermal CVD methods such as MOCVD or atomic layer deposition (ALD) can also be used. good.

[0172] In this embodiment, a glass substrate is used as the substrate 102, which functions as the first gate electrode. A tungsten film having a thickness of 100 nm is formed as the conductive film 104 by sputtering. .

[0173] The insulating films 106 and 107 functioning as the first gate insulating film are formed by sputtering, PE The film can be formed by using a CVD method, a thermal CVD method, a vacuum deposition method, a PLD method, or the like. In this embodiment, a silicon nitride film having a thickness of 400 nm is formed as the insulating film 106 by the PECVD method. Then, a silicon oxynitride film is formed as the insulating film 107 to a thickness of 50 nm.

[0174] The insulating film 106 may have a stacked structure of a silicon nitride film. The insulating film 106 is made of a first silicon nitride film, a second silicon nitride film, and a third silicon nitride film. A three-layer laminate structure with a silicon film can be formed. An example of the three-layer laminate structure is as follows: It can be formed as follows:

[0175] The first silicon nitride film is formed by, for example, silane at a flow rate of 200 sccm, PE-CV was performed using nitrogen at a flow rate of 100 sccm and ammonia gas at a flow rate of 100 sccm as source gas. The pressure in the reaction chamber was controlled to 100 Pa, and a 27.12 MHz high-frequency If a power of 2000 W is supplied using a frequency power supply and the thickness is formed to be 50 nm, good.

[0176] For the second silicon nitride film, silane at a flow rate of 200 sccm, The nitrogen gas and the ammonia gas with a flow rate of 2000sccm were used as raw material gases in the PECVD equipment. The pressure in the reaction chamber was controlled to 100 Pa, and a 27.12 MHz high-frequency power supply was used. A power of 2000 W may be supplied using the above method to form a film having a thickness of 300 nm.

[0177] The third silicon nitride film was prepared by using silane at a flow rate of 200 sccm and 5000 sccm. The pressure in the reaction chamber was kept at 100 The thickness was measured by controlling the temperature to 50 Pa and supplying 2000 W of power using a 27.12 MHz high frequency power source. It is sufficient to form it so that the thickness is 50 nm.

[0178] The first silicon nitride film, the second silicon nitride film, and the third silicon nitride film The substrate temperature during formation can be 350°C.

[0179] By forming the insulating film 106 in a three-layered structure of silicon nitride films, for example, the conductive film 10 When a conductive film containing copper (Cu) is used for 4, the following effects are achieved.

[0180] The first silicon nitride film can suppress the diffusion of copper (Cu) elements from the conductive film 104. The second silicon nitride film has the function of releasing hydrogen and functions as a gate insulating film. The third silicon nitride film has low hydrogen emission and can improve the breakdown voltage of the insulating film. Moreover, the diffusion of hydrogen released from the second silicon nitride film can be suppressed.

[0181] The insulating film 107 is formed by using a material having a thickness of 100 nm to improve interface characteristics with an oxide semiconductor film 108 to be formed later. Therefore, it is preferable that the insulating film be formed of an insulating film containing oxygen.

[0182] Next, the oxide semiconductor film 108 is formed over the insulating film 107 (see FIG. 9B).

[0183] In this embodiment, an In-Ga-Zn metal oxide target (In:Ga:Zn=1: an oxide semiconductor film was formed by sputtering using a SiO2 / SiO2 (atomic ratio of 1:1.2); A mask is formed on the oxide semiconductor film by a lithography process, and the oxide semiconductor film is By processing the oxide semiconductor film 108 into an island-shaped shape, the oxide semiconductor film 108 is formed.

[0184] After the oxide semiconductor film 108 is formed, the substrate is heated at 150° C. or higher and lower than the distortion point of the substrate, preferably at 200° C. A heat treatment at 300° C. or higher and 450° C. or lower may be performed. The heat treatment here is one of treatments for purifying the oxide semiconductor film. It is possible to reduce hydrogen, water, etc. contained in 108. The heat treatment may be performed before the oxide semiconductor film 108 is processed into an island shape.

[0185] The heat treatment on the oxide semiconductor film 108 can be performed using an electric furnace, an RTA apparatus, or the like. By using an RTA device, it is possible to perform heat treatment at a temperature above the distortion point of the substrate for a short period of time. Therefore, the heating time can be shortened.

[0186] Note that the heat treatment on the oxide semiconductor film 108 was performed using nitrogen, oxygen, or ultra-dry air (containing a low amount of water). 20 ppm or less, preferably 1 ppm or less, preferably 10 ppb or less, or The process may be carried out under an atmosphere of a rare gas (argon, helium, etc.). It is preferable that the dry air or rare gas does not contain hydrogen, water, etc. After the heat treatment in the nitrogen atmosphere, the material may be heated in an oxygen or ultra-dry air atmosphere. Hydrogen, water, and the like contained in the oxide semiconductor film are released, and oxygen is introduced into the oxide semiconductor film. As a result, the amount of oxygen vacancies in the oxide semiconductor film can be reduced. This can be done.

[0187] When the oxide semiconductor film 108 is formed by a sputtering method, a sputtering gas In the case of the above, a rare gas (typically argon), oxygen, or a mixed gas of a rare gas and oxygen is appropriately used. In the case of a mixed gas, it is preferable to increase the ratio of oxygen to rare gas. It is also necessary to increase the purity of the sputtering gas. For example, oxygen used as a sputtering gas The gas or argon gas has a dew point of -40°C or less, preferably -80°C or less, and more preferably By using gas that has been highly purified to temperatures below -100℃, and more preferably below -120℃, This can prevent moisture and the like from being absorbed into the oxide semiconductor film 108 as much as possible.

[0188] In addition, when the oxide semiconductor film 108 is formed by a sputtering method, a sputtering apparatus The chamber is designed to remove water and other impurities that may be contained in the oxide semiconductor film 108 as much as possible. In order to remove the gas, a high vacuum (5×10 -7 Pa to 1×10 -4 It is preferable to evacuate the gas to a temperature of about 10 Pa. A combination of a filter and a cold trap is used to extract gas, especially carbon or water, from the exhaust system into the chamber. It is preferable to prevent backflow of oxygen-containing gas.

[0189] Next, a source electrode and a drain electrode are formed over the insulating film 107 and the oxide semiconductor film 108. Functional conductive films 112a and 112b are formed (see FIG. 9C).

[0190] In this embodiment, the conductive films 112a and 112b are made of tungsten films having a thickness of 50 nm. A laminated film of the 400 nm thick aluminum film and the 400 nm thick aluminum film was formed by sputtering. A mask is formed on the layer film by a lithography process, and the layer film is processed into a desired shape. In this embodiment, the conductive films 112a and 112b are formed. However, the present invention is not limited to this. For example, the conductive film 112 a, 112b are tungsten films with a thickness of 50 nm and aluminum films with a thickness of 400 nm. Alternatively, the film may have a three-layered structure including a 100 nm-thick titanium film and a 100 nm-thick titanium film.

[0191] After the conductive films 112a and 112b are formed, the surface of the oxide semiconductor film 108 (back-cut The cleaning method may be, for example, cleaning with a chemical solution such as phosphoric acid. By performing cleaning using a chemical solution such as phosphoric acid, the surface of the oxide semiconductor film 108 can be cleaned. Remove impurities (such as elements contained in the conductive films 112a and 112b) adhering to the surface. It is possible.

[0192] In addition, when the conductive films 112a and 112b are formed and / or in the above cleaning process, oxidation A recess may be formed in a part of the semiconductor film 108 .

[0193] Through the above steps, the transistor 100 is formed.

[0194] Next, a semiconductor layer 108 of the transistor 100, specifically, the oxide semiconductor layer 108 of the transistor 100, and an insulating film serving as a protective insulating film for the transistor 100 is formed on the conductive films 112a and 112b. The membranes 114 and 116 are formed (see FIG. 9(D)).

[0195] After the insulating film 114 is formed, the insulating film 116 is successively formed without exposing it to the air. After the insulating film 114 is formed, it is preferable to adjust the flow rate, pressure, and temperature of the source gas without exposing the insulating film 114 to the air. By adjusting one or more of the frequency power and the substrate temperature, the insulating film 116 is continuously formed. The concentration of impurities derived from atmospheric components can be reduced at the interface between the insulating film 114 and the insulating film 116. At the same time, oxygen contained in the insulating films 114 and 116 is transferred to the oxide semiconductor film 108. As a result, the amount of oxygen vacancies in the oxide semiconductor film 108 can be reduced.

[0196] For example, a silicon oxynitride film is formed as the insulating film 114 by using a PECVD method. In this case, the source gas may be a deposition gas containing silicon and an oxidizing gas. Representative examples of deposition gases containing silicon include silane, disilane, etc. Examples of oxidizing gases include nitrous oxide, nitrous oxide, and trisilane. In addition, the oxidizing gas is more than 20 times and less than 100 times the deposition gas. and the pressure in the treatment chamber is less than 100 Pa, preferably 40 times or more and 80 times or less. By using the PECVD method at a pressure of 50 Pa or less, the insulating film 114 contains nitrogen, and The insulating film has a small number of defects.

[0197] In this embodiment, the insulating film 114 is formed by heating the substrate 102 at a temperature of 220° C. The source gases were silane at a flow rate of 50 sccm and dinitrogen monoxide at a flow rate of 2000 sccm. The pressure in the treatment chamber was set to 20 Pa, and the high frequency power supplied to the parallel plate electrodes was set to 13.56 M. Hz, 100W (power density is 1.6×10 -2 W / cm 2 ) PECVD method A silicon oxynitride film is formed using this.

[0198] The insulating film 116 is formed by depositing a substrate in a vacuum-evacuated processing chamber of a PECVD apparatus. The temperature is maintained at 180°C or higher and 280°C or lower, and more preferably 200°C or higher and 240°C or lower. A raw material gas is introduced into the chamber to set the pressure in the processing chamber to 100 Pa or more and 250 Pa or less, and The pressure is preferably 100 Pa or more and 200 Pa or less, and 0.17 W is applied to the electrodes provided in the processing chamber. / cm 2 More than 0.5W / cm 2 Less than or equal to 0.25 W / cm 2 More than 0.35 W / cm 2 Under the following conditions of high frequency power supply, silicon oxide film or silicon oxynitride film is Form a cone film.

[0199] The conditions for forming the insulating film 116 are as follows: high frequency power density in a reaction chamber with the above pressure; By supplying power, the efficiency of decomposition of the source gas in the plasma increases, and the number of oxygen radicals increases. As the oxidation of the source gas progresses, the oxygen content in the insulating film 116 becomes lower than the stoichiometric composition. On the other hand, in the film formed at the above substrate temperature, the bonding strength between silicon and oxygen is Since the oxygen in the film is weak, some of the oxygen in the film is released by the heat treatment in the subsequent process. An oxide that contains more oxygen than satisfies the theoretical composition and loses some of the oxygen when heated. An insulating film can be formed.

[0200] In the step of forming the insulating film 116, the insulating film 114 serves as a protection film for the oxide semiconductor film 108. Therefore, the power density can be reduced while reducing damage to the oxide semiconductor film 108. The insulating film 116 can be formed using high radio frequency power.

[0201] In the deposition conditions for the insulating film 116, a deposition gas containing silicon is mixed with an oxidizing gas. By increasing the flow rate of the gas, it is possible to reduce the amount of defects in the insulating film 116. In the first place, ESR measurements revealed that the g value was 2.001, which is due to the dangling bonds of silicon. The spin density of the signal is 6×10 17 spins / cm 3 Less than 3 x 10 17 spins / cm 3 Less than or equal to 1.5×10 17 spins / cm 3 The following is a missing It is possible to form an oxide insulating layer with few defects. As a result, the reliability of the transistor is improved. It can be done.

[0202] After the insulating films 114 and 116 are formed, heat treatment may be performed. The nitrogen oxides contained in the insulating films 114 and 116 can be reduced. As a result, part of oxygen contained in the insulating films 114 and 116 is transferred to the oxide semiconductor film 108. In this way, the amount of oxygen vacancies in the oxide semiconductor film 108 can be reduced.

[0203] The temperature for the heat treatment of the insulating films 114 and 116 is typically 150° C. or higher and 400° C. or lower. The temperature is preferably 300°C or higher and 400°C or lower, and more preferably 320°C or higher and 370°C or lower. 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 of air), or rare gases (argon, helium, etc.) The above-mentioned nitrogen, oxygen, ultra-dry air, or rare gas, hydrogen, water, etc. may be added to the atmosphere. For the heat treatment, an electric furnace, an RTA device, etc. may be used. do.

[0204] In this embodiment mode, heat treatment is performed in a nitrogen and oxygen atmosphere at 350° C. for one hour.

[0205] Next, a film 130 capable of suppressing the release of oxygen is formed on the insulating film 116 (FIG. 10(A)).

[0206] The film 130 having the function of suppressing oxygen release may be a conductive film containing indium, or A semiconductor film containing indium can be used.

[0207] In this embodiment, the film 130 having the function of suppressing the release of oxygen is a spa A 5 nm thick ITSO film is formed using a quenching apparatus. When the thickness is 1 nm or more and 20 nm or less, or 2 nm or more and 10 nm or less, oxygen can be suitably transmitted. This is also preferable because it can suppress the release of oxygen.

[0208] Next, oxygen 139 is introduced into the insulating films 114 and 116 and the oxide semiconductor film 108 through the film 130. is added (see FIG. 10(B)).

[0209] Oxygen 139 is added to the insulating films 114 and 116 and the oxide semiconductor film 108 through the film 130. Methods for this include ion doping, ion implantation, plasma treatment, and the like.

[0210] In addition, when oxygen-139 is added, a bias voltage is applied to the substrate side to effectively add oxygen. The element 139 can be added to the insulating films 114 and 116 and the oxide semiconductor film 108. The bias voltage is, for example, a voltage applied to the substrate side of an ashing device. The power density of the applied bias voltage is 1W / cm 2 More than 5W / cm 2 The following is sufficient. In addition, the substrate temperature when oxygen 139 is added is from room temperature to 300° C., preferably By setting the temperature to 100° C. or more and 250° C. or less, oxygen can be efficiently added to the insulating films 114 and 116. It is possible.

[0211] By providing the film 130 on the insulating film 116 and adding oxygen, the film 130 is The insulating films 114 and 11 function as protective films that suppress the release of oxygen from the insulating film 114. A large amount of oxygen can be added to the oxide semiconductor film 6 and the oxide semiconductor film 108.

[0212] In addition, when oxygen is introduced in plasma processing, the oxygen is excited by microwaves to produce high-density oxygen. By generating oxygen plasma, the amount of oxygen introduced into the insulating film 116 can be increased. .

[0213] Next, the film 130 having the function of suppressing the release of oxygen is etched using an etchant 142. Remove it (see Figure 10(C)).

[0214] The etchant 142 is an etchant capable of removing the film 130 having a function of suppressing the release of oxygen. Any chemical solution or etching gas may be used. An oxalic acid solution having a concentration of 5% is used as the etchant 142. 2 is a 5% oxalic acid solution, followed by 0.5% fluoride solution. Hydrofluoric acid may be used. By using 0.5% hydrofluoric acid, oxygen release can be suppressed. This makes it possible to suitably remove films having a function of removing the fluorine-containing film.

[0215] Next, an insulating film 118 is formed over the insulating film 116, thereby forming the transistor 10 shown in FIG. 0 is formed (see FIG. 10(D)).

[0216] When the insulating film 118 is formed by the PECVD method, the substrate temperature is set to 300° C. or more and 400° C. or less. Preferably, the temperature is 320° C. or higher and 370° C. or lower, since a dense film can be formed by the temperature being 320° C. or higher and 370° C. or lower. stomach.

[0217] For example, when a silicon nitride film is formed as the insulating film 118 by the PECVD method, the silicon It is preferable to use a deposition gas containing carbon, nitrogen, and ammonia as the source gas. By using a small amount of ammonia compared to nitrogen, ammonia dissociates in the plasma and becomes active. The active species are generated by reacting with silicon and hydrogen contained in the deposition gas containing silicon. This breaks the triple bond between silicon and nitrogen, promoting the bonding of silicon and nitrogen. To form a dense silicon nitride film with few bonds between silicon and hydrogen and few defects. On the other hand, if the amount of ammonia relative to nitrogen is large, the deposition gas containing silicon and Nitrogen decomposition does not progress, silicon and hydrogen bonds remain, defects increase, and roughness is generated. For these reasons, the source gas should be ammonia-free. The flow rate ratio of nitrogen to oxygen is preferably 5 or more and 50 or less, and more preferably 10 or more and 50 or less.

[0218] In this embodiment, the insulating film 118 is formed by depositing silane, nitrogen, etc., using a PECVD apparatus. A silicon nitride film with a thickness of 50 nm is formed from the raw material gases of nitrogen and ammonia. The flow rate is , silane at 50 sccm, nitrogen at 5000 sccm, and ammonia at 100 sccm The pressure in the processing chamber was 100 Pa, the substrate temperature was 350°C, and a high frequency of 27.12 MHz was used. A high-frequency power of 1000 W is supplied to the parallel plate electrodes using a high-frequency power source. The pole area is 6000cm 2 This is a parallel plate type PECVD device, and the supplied power is expressed as a unit. This translates to 1.7 x 10 power per area (power density). -1 W / cm 2 It is.

[0219] Note that a heat treatment is performed before or after the insulating film 118 is formed to obtain an insulating film. Excess oxygen contained in the films 114 and 116 is diffused into the oxide semiconductor film 108, and the oxide semiconductor Alternatively, the insulating film 118 can be formed by heating and filling the oxygen vacancies in the insulating film 108. By this, excess oxygen contained in the insulating films 114 and 116 is diffused into the oxide semiconductor film 108. Thus, oxygen vacancies in the oxide semiconductor film 108 can be filled. The temperature of the heat treatment, which can be performed before or after the formation of the insulating film 118, is typically 150°C or higher and 400°C or lower, preferably 300°C or higher and 400°C or lower, preferably 320°C The temperature must be above 370℃.

[0220] Through the above steps, the transistor 100 illustrated in FIG. 1 can be manufactured.

[0221] <Method 2 for manufacturing semiconductor device> Next, a method for manufacturing the transistor 150, which is a semiconductor device of one embodiment of the present invention, illustrated in FIG. This will be described in detail below with reference to FIG. 11 and FIG.

[0222] First, the steps up to the step shown in FIG. 9B are performed, and then the insulating film 107 and the oxide semiconductor film 1 On the substrate 08, insulating films 114 and 116 and a film 130 having a function of suppressing oxygen release are formed. (See FIG. 11(A)).

[0223] Next, the insulating films 114, 116, Furthermore, oxygen 139 is added to the oxide semiconductor film 108 (see FIG. 11B).

[0224] Next, the film 130 having the function of suppressing the release of oxygen is etched using an etchant 142. Remove it (see FIG. 11(C)).

[0225] Next, a mask is formed on the insulating film 116 by a lithography process, and the insulating film 114 and the insulating film 116 are Openings 141a and 141b are formed in desired regions of the membrane 116. , 141b reach the oxide semiconductor film 108 (see FIG. 11D).

[0226] Next, the oxide semiconductor film 108 and the insulating film 11 are formed so as to cover the openings 141a and 141b. A conductive film is formed on the conductive film by a lithography process, and a mask is formed on the conductive film. The conductive film 112a and the conductive film 112b are formed by processing the conductive film 112a and the conductive film 112b into a desired shape (see FIG. 12(A)). (see).

[0227] Next, an insulating film 118 is formed on the insulating film 116 and the conductive films 112a and 112b (FIG. 12(B)).

[0228] Through the above steps, the transistor 150 shown in FIG. 4 can be manufactured.

[0229] Note that the transistor 160 shown in FIGS. 5A, 5B, and 5C has an opening 141a, When forming the insulating film 114 and the insulating film 111b, the insulating film 111b is formed on the channel region of the oxide semiconductor film 108. It can be fabricated by leaving 6.

[0230] <Method 3 for manufacturing semiconductor device> Next, a method for manufacturing a transistor 170 which is a semiconductor device of one embodiment of the present invention and is illustrated in FIG. This will be described in detail below with reference to FIG. 13 and FIG.

[0231] 13(A)(C) and 14(A)(C) show the transistor in the manufacturing process. 13(B)(D) and 14(B)(D) show cross-sectional views of the channel length direction of the capacitor 170. 1A is a cross-sectional view of a transistor 170 in a channel width direction during a manufacturing process.

[0232] First, the steps up to the step shown in FIG. 10(D) are carried out (see FIGS. 13(A) and (B)).

[0233] Next, a mask is formed on the insulating film 118 by a lithography process, and the insulating films 114 and 11 An opening 142c is formed in a desired region of the insulating film 118. A mask is formed by a photolithography process, and the desired insulating films 106, 107, 114, 116, and 118 are formed. In this region, openings 142a and 142b are formed. The openings 142a and 142b are formed so as to reach the conductive film 10 4 (see Figures 13(C) and (D)).

[0234] The openings 142a, 142b and the opening 142c may be formed at the same time or in different locations. The openings 142a, 142b and the opening 142c may be formed at the same time. In this case, for example, a gray-tone mask or a half-tone mask can be used. Cut.

[0235] Next, a conductive film 12 is formed on the insulating film 118 so as to cover the openings 142a, 142b, and 142c. 0 (see Figures 14(A) and (B)).

[0236] The conductive film 120 may be made of, for example, indium (In), zinc (Zn), or tin (Sn). In particular, the conductive film 120 may be made of a material containing one selected from the group consisting of an acid, Indium oxide containing tungsten oxide, Indium zinc oxide containing tungsten oxide , indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium Transparent materials such as indium tin oxide, indium zinc oxide, and indium tin oxide containing silicon oxide In addition, the conductive film 120 can be made of a conductive material that can suppress the release of oxygen. By using the same material as the film 130 having the function of being able to perform the above-mentioned function, the manufacturing cost can be reduced, which is preferable. It is appropriate.

[0237] The conductive film 120 can be formed by, for example, a sputtering method. In this embodiment, an ITSO film having a thickness of 110 nm is formed by sputtering. do.

[0238] Next, a mask is formed on the conductive film 120 by a lithography process, and the conductive film 120 is Then, the conductive film 120a and the conductive film 120b are formed (see FIGS. 14C and 14D).

[0239] Through the above steps, the transistor 170 shown in FIG. 6 can be manufactured.

[0240] The structures and methods described in this embodiment mode may be appropriately combined with the structures and methods described in other embodiment modes. They can be used in combination.

[0241] (Embodiment 2) In this embodiment, a structure of an oxide semiconductor film included in a semiconductor device of one embodiment of the present invention will be described. This will be explained in detail below.

[0242] Oxide semiconductor films are roughly classified into non-single-crystal oxide semiconductor films and single-crystal oxide semiconductor films. The non-single-crystal oxide semiconductor film is called CAAC-OS (C Axis Aligned Crystal-Oxide Semiconductor Film). (stalline oxide semiconductor) film, polycrystalline oxide semiconductor The oxide semiconductor film includes a film, a microcrystalline oxide semiconductor film, an amorphous oxide semiconductor film, and the like.

[0243] First, we will explain the CAAC-OS film.

[0244] The CAAC-OS film is one of the oxide semiconductor films that has multiple crystal parts aligned along the c-axis. .

[0245] Transmission Electron Microscope (TEM) A combined analysis image of the bright-field image and diffraction pattern of the CAAC-OS film was obtained by a microscope. (also called high-resolution TEM image) allows multiple crystals to be identified. On the other hand, the high-resolution TEM image also clearly shows the boundaries between crystals, i.e., grain boundaries. Therefore, the CAAC-OS film is It can be said that the decrease in electron mobility caused by the grain boundaries is unlikely to occur.

[0246] When a high-resolution TEM image of the cross section of the CAAC-OS film was observed from a direction approximately parallel to the sample surface, It can be seen that the metal atoms are arranged in layers in the crystal part. Each layer of metal atoms is The CAAC-OS film is formed on the surface (also called the surface on which the film is formed) or on the upper surface. The CAAC-OS film has a shape similar to that of the crystalline silicon film, and is aligned parallel to the surface on which the CAAC-OS film is formed or the upper surface.

[0247] On the other hand, a high-resolution TEM image of the plane of the CAAC-OS film was observed from a direction almost perpendicular to the sample surface. They then confirmed that the metal atoms in the crystals were arranged in triangular or hexagonal shapes. However, there is no regularity in the arrangement of metal atoms between different crystal parts.

[0248] X-ray diffraction (XRD) of CAAC-OS film When the structure was analyzed using the device, for example, CAAC-OS with InGaZnO4 crystals was In the out-of-plane analysis of the film, the diffraction angle (2θ) peaked at around 31°. This peak is attributed to the (009) plane of the InGaZnO4 crystal. Therefore, the crystals of the CAAC-OS film have a c-axis orientation, and the c-axis faces the surface on which the film is formed or the upper surface. It can be seen that it is oriented in a substantially vertical direction.

[0249] In addition, the out-of-plane crystal structure of the CAAC-OS film with InGaZnO4 crystals In the analysis by the method, in addition to the peak at 2θ near 31°, a peak also appeared at 2θ near 36°. The peak at 2θ of around 36° may be due to the c-axis orientation in some parts of the CAAC-OS film. The CAAC-OS film contains crystals that do not have the 2θ value of about 31°. It is preferable that the spectrum shows a peak at 2θ of about 36° and does not show a peak at 2θ of about 36°.

[0250] The CAAC-OS film is an oxide semiconductor film with a low concentration of impurities. The oxide semiconductor film is preferably made of silicon or a transition metal element other than the main component of the oxide semiconductor film. The elements that bond to oxygen stronger than the metal elements that form the oxide semiconductor film, such as Zn, By removing oxygen from the oxide semiconductor film, the atomic arrangement of the oxide semiconductor film is disturbed, and the crystallinity is reduced. In addition, heavy metals such as iron and nickel, argon, and carbon dioxide are Since the diameter (or molecular radius) of the ions is large, when the ions are contained inside the oxide semiconductor film, the oxide semiconductor film The impurities contained in the oxide semiconductor film are disturbed, which causes a decrease in crystallinity. Pure materials may act as carrier traps or carrier generation sources.

[0251] The CAAC-OS film is an oxide semiconductor film with a low density of defect states. Oxygen vacancies in semiconductor films act as carrier traps and trap hydrogen. This can become a carrier generation source.

[0252] The low impurity concentration and low defect level density (low oxygen vacancies) are called high purity intrinsic or The term "high-purity intrinsic" refers to a substantially high-purity intrinsic oxide semiconductor. Since the film has a small number of carrier generation sources, the carrier density can be reduced. The transistor including the oxide semiconductor film has an electrical characteristic in which the threshold voltage is negative. (also called normally-on). An oxide semiconductor film having an intrinsic purity has few carrier traps. Transistors using conductor films have little fluctuation in electrical characteristics and are highly reliable. Note that it takes a certain amount of time for charges trapped in the carrier traps in the oxide semiconductor film to be released. The time it takes for the charge to reach the charge limit is long, and it may behave as if it were a fixed charge. A transistor using an oxide semiconductor film having a high density of defect states has unstable electrical characteristics. This may be the case.

[0253] In addition, the electrical characteristics of transistors using CAAC-OS films are improved by irradiation with visible light or ultraviolet light. Gender variation is small.

[0254] Next, a microcrystalline oxide semiconductor film will be described.

[0255] In the microcrystalline oxide semiconductor film, crystal parts can be confirmed in a high-resolution TEM image. The microcrystalline oxide semiconductor has a region where a crystal part is not clearly observed, and a region where a crystal part is not clearly observed. The crystal parts contained in the film are large, with sizes ranging from 1 nm to 100 nm, or from 1 nm to 10 nm. In particular, the size is between 1 nm and 10 nm, or between 1 nm and 3 nm. The oxide semiconductor film having nanocrystals (nc) is c-OS(nanocrystalline oxide semiconductor In addition, the nc-OS film is called a crystalline structure. For example, in a high-resolution TEM image, the grain boundaries are clearly visible. It may not be possible to verify.

[0256] The nc-OS film is a microscopic region (e.g., a region of 1 nm to 10 nm, especially a region of 1 nm or less). The nc-OS film has a periodic atomic arrangement in the region of 3 nm or less. There is no regularity in the crystal orientation between the crystal parts, and therefore no orientation is observed throughout the film. Therefore, the nc-OS film cannot be distinguished from an amorphous oxide semiconductor film depending on the analysis method. For example, in the case of nc-OS films, X-rays with a diameter larger than that of the crystals are used. When structural analysis is performed using an RD device, the crystal No peaks indicating the crystal plane were detected. Electron diffraction using an electron beam with a diameter of 50 nm or more (also called selected area electron diffraction) When the diffraction pattern is changed to nc-OS film, a halo-like diffraction pattern is observed. Nano-beam electrons are used to measure the size of the crystals using an electron beam with a probe diameter close to or smaller than the size of the crystals. When nanobeam electron diffraction is performed on the nc-OS film, spots are observed. When performing this, a circular (ring-shaped) area of ​​high brightness may be observed. Nanobeam electron diffraction of the nc-OS film revealed multiple spots within the ring-shaped region. may be observed.

[0257] The nc-OS film is an oxide semiconductor film that has higher order than an amorphous oxide semiconductor film. Therefore, the nc-OS film has a lower density of defect states than the amorphous oxide semiconductor film. In the nc-OS film, the crystal orientation is not regular between different crystal parts. The OS film has a higher density of defect states than the CAAC-OS film.

[0258] Next, the amorphous oxide semiconductor film will be described.

[0259] The amorphous oxide semiconductor film has an irregular atomic arrangement in the film and does not have a crystal part. An example is an oxide semiconductor film that has an amorphous state like quartz.

[0260] In the amorphous oxide semiconductor film, no crystalline parts can be confirmed in a high-resolution TEM image. .

[0261] When the structure of the amorphous oxide semiconductor film is analyzed using an XRD device, out-of- In the plane analysis, no peaks indicating crystal planes were detected. When electron diffraction is performed on a semiconductor film, a halo pattern is observed. When nanobeam electron diffraction is performed on a semiconductor film, no spots are observed, and a halo pattern is observed. is observed.

[0262] Note that the oxide semiconductor film has a structure that exhibits physical properties intermediate between the nc-OS film and the amorphous oxide semiconductor film. An oxide semiconductor film having such a structure may be used, particularly in the case of an amorphous like oxide film. Amorphous-like Oxide Semiconductor (a-like OS) The conductive film is called an iconductor film.

[0263] In the a-like OS film, voids are observed in the high-resolution TEM image. In addition, crystals may not be clearly visible in high-resolution TEM images. The a-like OS film has regions where crystals are visible and regions where no crystals are visible. Crystallization occurs when a small amount of electrons is irradiated, which is the level observed in TEM observations, and the growth of the crystals can be seen. On the other hand, in the case of a good quality nc-OS film, the amount of TEM observation is small. Almost no crystallization due to electron irradiation was observed.

[0264] The size of the crystals in the a-like OS film and the nc-OS film was measured using a high-resolution This can be done using TEM images. For example, InGaZnO4 crystals have a layered structure. InGaZnO4, there are two Ga-Zn-O layers between the In-O layers. The device has three In-O layers and six Ga-Zn-O layers, for a total of nine layers aligned along the c-axis. It has a layered structure. Therefore, the spacing between adjacent layers is (009) The lattice spacing (also called the d value) of m. Therefore, focusing on the lattice fringes in the high-resolution TEM image, In the area where the spacing is 0.28 nm or more and 0.30 nm or less, each lattice fringe is In It corresponds to the ab plane of the GaZnO4 crystal.

[0265] In addition, the density of an oxide semiconductor film may differ depending on the structure. If the composition of the conductive film is known, the density can be determined by comparing it with the density of a single crystal with the same composition. For example, the density of a single crystal is The density of the -like OS film is 78.6% or more and less than 92.3%. The density of the nc-OS film and the CAAC-OS film is 92.3% or more of the density of the crystals. Note that an oxide semiconductor film having a density of less than 78% of the density of a single crystal is Therefore, the film formation itself is difficult.

[0266] The above will be explained using a specific example. For example, In the oxide semiconductor film that satisfies the [atomic ratio], single crystal InGaZnO with a rhombohedral crystal structure The density of 4 is 6.357g / cm 3 Therefore, for example, In:Ga:Zn=1:1: In the oxide semiconductor film that satisfies the atomic ratio of 1, the density of the a-like OS film is 5.0 g / cm 3 More than 5.9g / cm 3 For example, In:Ga:Zn=1:1 In the oxide semiconductor film that satisfies the atomic ratio of 1:1, the density and CAAC of the nc-OS film -OS film density is 5.9g / cm 3 More than 6.3g / cm 3 It will be less than.

[0267] In some cases, single crystals of the same composition do not exist. In such cases, crystals of different compositions may be used in any ratio. By combining single crystals of the desired composition, the density corresponding to the single crystal of the desired composition can be calculated. The density of a single crystal of a desired composition varies with the ratio of the single crystals of different compositions combined. However, the density should be calculated using as few types of single crystals as possible. It is preferable to calculate the above in combination.

[0268] The oxide semiconductor film may be, for example, an amorphous oxide semiconductor film, an a-like OS film, or a micro- The semiconductor layer may be a stacked film including two or more of a crystalline oxide semiconductor film and a CAAC-OS film. .

[0269] The structure described in this embodiment may be used in appropriate combination with structures described in other embodiments. can be done.

[0270] (Embodiment 3) In this embodiment, a display device including the transistor described in the above embodiment will be An example will be described below with reference to FIGS.

[0271] 15 is a top view showing an example of a display device. The display device 700 shown in FIG. A pixel portion 702 is provided on the first substrate 701, and a source driver is provided on the first substrate 701. A pixel portion 702, a source driver circuit portion 704, a gate driver circuit portion 706, A sealant 712 is disposed so as to surround the path portion 704 and the gate driver circuit portion 706. and a second substrate 705 disposed so as to face the first substrate 701. The first substrate 701 and the second substrate 705 are sealed with a sealant 712. That is, the pixel section 702, the source driver circuit section 704, and the gate driver circuit section 706 are The first substrate 701, the sealant 712, and the second substrate 705 seal the entire structure. Although not shown in FIG. 15, a display element is provided between the first substrate 701 and the second substrate 705. can be done.

[0272] The display device 700 is surrounded by a sealant 712 on the first substrate 701. A pixel section 702, a source driver circuit section 704, and a gate driver circuit section 705 are arranged in a region different from the region. and an FPC terminal portion 708 (FPC: Flexible Printed Circuit portion 706) electrically connected to the In addition, the FPC terminal portion 708 is provided with The FPC 716 is connected to the pixel section 702 and the source driver circuit Various signals are supplied to the pixel section 704 and the gate driver circuit section 706. 02, a source driver circuit section 704, a gate driver circuit section 706, and an FPC terminal section 7 08 are connected to signal lines 710. Various signals are supplied by the FPC 716. 7, are connected to a pixel section 702, a source driver circuit section 704, a gate driver circuit section 705, and the like via a signal line 710. The wiring is provided to a driver circuit portion 706 and an FPC terminal portion 708.

[0273] The display device 700 may include a plurality of gate driver circuits 706. The device 700 includes a source driver circuit section 704 and a gate driver circuit section 706. Although an example in which the pixel portion 702 is formed on the same first substrate 701 is shown, the present invention is not limited to this configuration. For example, only the gate driver circuit section 706 may be formed on the first substrate 701. Alternatively, only the source driver circuit portion 704 may be formed on the first substrate 701. In this case, the substrate on which the source driver circuit or the gate driver circuit is formed (for example, A driving circuit board formed of a monocrystalline semiconductor film or a polycrystalline semiconductor film is mounted on a first substrate 701. The method of connecting the separately formed drive circuit board is not particularly limited. Instead, we use COG (Chip On Glass) method, wire bonding method, etc. can be used.

[0274] The display device 700 also includes a pixel portion 702, a source driver circuit portion 704, and a gate The driver circuit portion 706 includes a plurality of transistors. A transistor having a specific position can be applied.

[0275] The display device 700 can also include various elements, such as: Liquid crystal elements, EL (electroluminescence) elements (EL elements containing organic and inorganic materials, Organic EL elements, inorganic EL elements), LEDs (white LEDs, red LEDs, green LEDs, blue LEDs ED, etc.), transistors (transistors that emit light according to the current), electron emitters, electron Ink, electrophoretic element, grating light valve (GLV), plasma display (PDP), a display element using MEMS (microelectromechanical systems) Digital Micromirror Device (DMD), Digital MicroShutter MIRASOL (registered trademark), IMOD (Interference Modulation MEMS display elements using the shutter method, MEMS display elements using the optical interference method, Using chromium-based wetting elements, piezoelectric ceramic displays, and carbon nanotubes In addition to these, the display element has at least one of electrical or magnetic functions. Even if the display medium has a variable contrast, brightness, reflectance, transmittance, etc. depending on the use, An example of a display device using an EL element is an EL display. One example of a display device using an emission element is the field emission display (FED). ) or SED type flat panel display (SED: Surface-conduction LCDs using liquid crystal elements. An example of a display device is a liquid crystal display (transmissive liquid crystal display, semi-transmissive liquid crystal display, etc.). LCD, reflective LCD, direct-view LCD, projection LCD An example of a display device using electronic ink or electrophoretic elements is an electronic pen. In addition, there are also other LCDs that can realize semi-transmissive LCDs and reflective LCDs. In this case, a part or the whole of the pixel electrode is made to function as a reflective electrode. For example, a part or the whole of the pixel electrode may be made of aluminum, silver, etc. In this case, a memory circuit such as an SRAM may be provided under the reflective electrode. This makes it possible to further reduce power consumption.

[0276] The display method of the display device 700 may be a progressive method or an interlace method. In addition, the color elements controlled by pixels when displaying in color are R It is not limited to the three colors GB (R stands for red, G stands for green, B stands for blue). For example, It may be composed of four pixels: a pixel, a pixel, and a pixel of white (W). As in the column, two colors of RGB compose one color element, and two different colors are created by the color element. Alternatively, one or more colors such as yellow, cyan, magenta, etc. may be selected for RGB. The size of the display area may be different for each dot of the color element. However, the disclosed invention is not limited to color display devices, and may be used with monochrome displays. The present invention can also be applied to display devices such as those shown in FIG.

[0277] In addition, the backlight (organic EL element, inorganic EL element, LED, fluorescent lamp, etc.) is white light ( In order to display full color on a display device, a colored layer (also called a color filter) is used. The colored layer may be, for example, red (R), green (G), blue (B) , yellow (Y), etc. can be used in appropriate combination. The color reproducibility can be improved compared to when no color layer is used. By disposing a region having a colored layer and a region not having a colored layer, The white light in the region may be directly used for display. This reduces the decrease in brightness caused by the colored layer during bright display, reducing power consumption by 20%. However, it may be possible to reduce the amount of light emitted by organic EL elements and inorganic EL elements by about 30%. When using elements to display full color, R, G, B, Y, and white (W) are It is also possible to emit light from an element having a luminescent color. By using a self-luminous element, it is possible to use a colored layer. In some cases, power consumption can be reduced even further than when the

[0278] In this embodiment, a liquid crystal element and an EL element are used as display elements. 16 and 17. Note that FIG. 16 shows the state of the circuit shown in FIG. 15 along the dashed line QR. FIG. 17 is a cross-sectional view of the liquid crystal display device, which uses a liquid crystal element as a display element. 15 is a cross-sectional view taken along dashed line QR in FIG. 15, and shows a configuration in which an EL element is used as a display element. It is.

[0279] First, the common parts shown in FIG. 16 and FIG. 17 will be explained, and then the different parts will be explained. This will be explained below.

[0280] <Explanation of common parts of display device> The display device 700 shown in FIG. 16 and FIG. 17 includes a wiring portion 711 and a pixel portion 702. The display panel 700 includes a source driver circuit section 704 and an FPC terminal section 708. The line portion 711 includes a signal line 710. The pixel portion 702 includes a transistor 750 and The source driver circuit portion 704 includes a transistor 752. Yes.

[0281] The transistors 750 and 752 may be the transistors shown above. can.

[0282] The transistor used in this embodiment is made of a highly purified oxide film in which the formation of oxygen vacancies is suppressed. The transistor has a semiconductor film. Therefore, the retention time of electric signals such as image signals can be extended, and the power supply When the write interval is on, it is possible to set it longer. This reduces the frequency of refresh operations. This has the effect of reducing power consumption.

[0283] In addition, the transistor used in this embodiment has a relatively high field-effect mobility. For example, a transistor capable of such high speed operation can be used for a liquid crystal display. By using this in a display device, the switching transistor in the pixel section and the driver circuit section In other words, the driver transistor can be formed on the same substrate as the driver circuit. Therefore, it is not necessary to use a semiconductor device formed from a silicon wafer or the like. The number of components can be reduced. By using a register, a high quality image can be provided.

[0284] The capacitor 790 has a structure having a dielectric between a pair of electrodes. One electrode of the transistor 790 is a conductive film that functions as a gate electrode of the transistor 750. The other electrode of the capacitor 790 is formed using a conductive film formed in the same process as that of the transistor. A conductive film is used to function as the source electrode and the drain electrode of the transistor 750. The dielectric sandwiched between the electrodes functions as the gate insulating film of the transistor 750. An insulating film is used.

[0285] 16 and 17, a transistor 750, a transistor 752, and a capacitor Over the quantum dot element 790, insulating films 764, 766, and 768, an oxide semiconductor film 767, and a planarizing An insulating film 770 is provided.

[0286] The insulating films 764, 766, and 768 are the same as the insulating film 114 shown in the previous embodiment. , 116, 118 can be formed by the same material and manufacturing method. The oxide semiconductor film 767 may be formed of the same material as the oxide semiconductor film 117 described in the above embodiment. The planarization insulating film 770 can be formed by the above-mentioned method. resin, acrylic resin, polyimide amide resin, benzocyclobutene resin, polyamide resin Heat-resistant organic materials such as grease and epoxy resin can be used. The planarization insulating film 770 may be formed by stacking a plurality of insulating films made of the same material. Further, the planarization insulating film 770 does not necessarily have to be provided.

[0287] The signal line 710 is connected to the source and drain electrodes of the transistors 750 and 752. The signal line 710 is formed in the same process as the conductive film that functions as the transistor 75. 0, 752, a conductive film formed in a process different from the source electrode and drain electrode, e.g., The signal line 710 may be a conductive film that functions as a conductive electrode. When this material is used, there is little signal delay caused by wiring resistance, making it possible to display images on a large screen. do.

[0288] The FPC terminal portion 708 includes a connection electrode 760, an anisotropic conductive film 780, and an FPC 71. 6. The connection electrode 760 is connected to the source and drain electrodes of the transistors 750 and 752. The connection electrode 760 is formed in the same process as the conductive film that functions as the drain electrode. The terminal of the PC 716 is electrically connected via an anisotropic conductive film 780 .

[0289] The first substrate 701 and the second substrate 705 may be, for example, a glass substrate. In addition, the first substrate 701 and the second substrate 705 may be flexible substrates. The flexible substrate may be, for example, a plastic substrate. do.

[0290] In addition, a structure 778 is provided between the first substrate 701 and the second substrate 705. The structure 778 is a columnar spacer obtained by selectively etching an insulating film. A device for controlling the distance (cell gap) between the first substrate 701 and the second substrate 705 is provided. In addition, a spherical spacer may be used as the structure 778. In this embodiment, the structure 778 is provided on the first substrate 701 side. However, the present invention is not limited to this. For example, a structure 778 may be provided on the second substrate 705 side. Alternatively, the structures 778 may be provided on both the first substrate 701 and the second substrate 705. .

[0291] In addition, on the second substrate 705 side, a light-shielding film 738 functioning as a black matrix and A colored film 736 that functions as a color filter, a light-shielding film 738 that is in contact with the colored film 736, and An insulating film 734 is provided.

[0292] <Example of the configuration of a display device using a liquid crystal element as a display element> The display device 700 shown in FIG. 16 includes a liquid crystal element 775. The liquid crystal element 775 includes a conductive film The conductive film 774 is a second substrate 705. The display device 700 shown in FIG. The alignment state of the liquid crystal layer 776 changes depending on the voltage applied to the conductive film 772 and the conductive film 774. By controlling the light transmission or non-transmission, an image can be displayed.

[0293] The conductive film 772 serves as a source electrode and a drain electrode of the transistor 750. The conductive film 772 is connected to a conductive film that functions as a pixel electrode. The conductive film 772 functions as a reflective electrode, that is, one of the electrodes of the display element. The display device 700 shown in FIG. and displays the reflected light through the colored film 736, that is, the so-called reflective color liquid crystal display device.

[0294] The conductive film 772 may be a conductive film that transmits visible light or a conductive film that reflects visible light. A conductive film having a reflectivity can be used. For example, a material containing one of the elements indium (In), zinc (Zn), and tin (Sn) As a conductive film that is reflective in visible light, for example, aluminum In this embodiment, the conductive film 772 may be formed of A conductive film that is reflective in visible light is used.

[0295] In addition, when a conductive film that is reflective to visible light is used as the conductive film 772, the conductive film The film may have a laminated structure. For example, an aluminum film having a thickness of 100 nm is formed on the lower layer, A 30 nm thick silver alloy film (e.g., an alloy film containing silver, palladium, and copper) is formed on the upper layer. The above-mentioned structure provides the following excellent effects.

[0296] (1) The adhesion between the base film and the conductive film 772 can be improved. It is possible to etch the aluminum film and the silver alloy film at the same time. The cross-sectional shape of the conductive film 772 can be made to be a good shape (for example, a tapered shape). The reason for this is that the aluminum film is etched slower by chemicals than the silver alloy film. Or, after etching the upper silver alloy film, the lower aluminum film is exposed. The electrons are taken from aluminum, which is a metal with a lower ionization tendency than gold. Because of this, etching of the silver alloy film is suppressed and etching of the underlying aluminum film is suppressed. This is because the progression is faster.

[0297] In the display device 700 shown in FIG. 16, the planarization insulating film 770 of the pixel section 702 The unevenness is formed in a part of the insulating film 770 by, for example, forming an organic resin film. The reflecting current can be formed by forming a reflecting current on the surface of the organic resin film. The conductive film 772, which functions as an electrode, is formed along the above-mentioned unevenness. When light enters the conductive film 772, the light can be diffusely reflected on the surface of the conductive film 772. This makes it possible to improve visibility.

[0298] The display device 700 shown in FIG. 16 is a reflective color liquid crystal display device. However, the conductive film 772 is not limited to this. For example, a conductive film that transmits visible light may be used. A transparent color liquid crystal display device may be formed by using a conductive film. In the case of the device, the unevenness provided on the planarization insulating film 770 may not be provided. stomach.

[0299] Although not shown in FIG. 16, the conductive films 772 and 774 on the side in contact with the liquid crystal layer 776 In addition, although not shown in FIG. Optical members (optical substrates) such as optical members, phase difference members, and anti-reflection members may be provided as appropriate. For example, circularly polarized light produced by a polarizing substrate and a retardation substrate may be used. Crites, sidelights, etc. may also be used.

[0300] When liquid crystal elements are used as display elements, thermotropic liquid crystal, low molecular weight liquid crystal, high molecular weight liquid crystal, 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.

[0301] In addition, when the in-plane switching method is adopted, 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 a cholesteric liquid crystal is increased, the cholesteric The blue phase appears just before the transition from the black phase to the isotropic phase. In order to improve the temperature range, a liquid crystal composition containing a chiral agent of several weight percent or more is used. The liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent is used in the liquid crystal layer. It has a short response time and is optically isotropic. It also contains a liquid crystal that exhibits a blue phase and a chiral agent. The liquid crystal composition does not require alignment treatment and has little viewing angle dependency. Since the rubbing process is unnecessary, the electrostatic breakdown caused by the rubbing process is eliminated. Therefore, defects and damage to the liquid crystal display device during the manufacturing process can be reduced. do.

[0302] In addition, when liquid crystal elements are used as display elements, TN (Twisted Nematic) ) mode, IPS (In-Plane-Switching) mode, FFS (Frin ge Field Switching) mode, ASM (Axially Symme tric aligned Micro-cell) mode, OCB(Optical Compensated Birefringence mode, FLC (Ferrero lectric Liquid Crystal) mode, AFLC (AntiFerr Electrochemical Liquid Crystal (ECC) mode can be used. .

[0303] In addition, normally black type liquid crystal display devices, for example, those using a vertical alignment (VA) mode The vertical alignment mode may be a transmission type liquid crystal display device. For example, MVA (Multi-Domain Vertical Alignment) ) mode, PVA (Patterned Vertical Alignment) mode mode, ASV mode, etc. can be used.

[0304] <Display device using light-emitting elements as display elements> The display device 700 shown in FIG. 17 includes a light-emitting element 782. The light-emitting element 782 is a conductive film The display device 700 shown in FIG. The EL layer 786 of the light element 782 emits light, thereby displaying an image. do.

[0305] The conductive film 784 serves as a source electrode and a drain electrode of the transistor 750. The conductive film 784 is connected to a conductive film that functions as a pixel electrode. The conductive film 784 functions as an electrode, that is, one of the electrodes of the display element. In the above, a conductive film that transmits light or a conductive film that reflects visible light can be used. Examples of conductive films that are transparent to visible light include indium (In), zinc (Zn), and ZnO. It is recommended to use a material containing one of the following elements: Zn (Zn) or tin (Sn). The reflective conductive film may be made of a material containing aluminum or silver. stomach.

[0306] In addition, in the display device 700 shown in FIG. An insulating film 730 is provided. The insulating film 730 covers a part of the conductive film 784. 782 has a top emission structure. Therefore, the conductive film 788 has a light transmitting property, and It transmits the light emitted by the L layer 786. In this embodiment, the top emission The structure is exemplified, but is not limited to this. For example, a bottom emission structure in which light is emitted to both the conductive film 784 and the conductive film 788; It can also be applied to al-emission structures.

[0307] A colored film 736 is provided at a position overlapping the light emitting element 782, and a colored film 736 is provided at a position overlapping the insulating film 730. A light-shielding film 738 is provided at the position where the light-shielding film 738 is to be formed, the wiring portion 711, and the source driver circuit portion 704. The colored film 736 and the light-shielding film 738 are covered with an insulating film 734. In addition, the space between the light emitting element 782 and the insulating film 734 is filled with a sealing film 732. In the display device 700 shown in FIG. 1, a configuration in which a colored film 736 is provided is illustrated. For example, when the EL layer 786 is formed by coloring, The film 736 may not be provided.

[0308] The structure described in this embodiment may be used in appropriate combination with structures described in other embodiments. can be done.

[0309] (Embodiment 4) In this embodiment, a display device including a semiconductor device according to one embodiment of the present invention will be described with reference to FIG. This will be used to explain.

[0310] The display device shown in FIG. 18A has a region having pixels of a display element (hereinafter, referred to as a pixel portion 502). ) and a circuit section ( hereinafter referred to as a drive circuit section 504) and a circuit having a function of protecting the element (hereinafter referred to as a protection circuit 50 6) and a terminal portion 507. Note that the protection circuit 506 is not provided. This is also fine.

[0311] A part or the whole of the driver circuit portion 504 is formed on the same substrate as the pixel portion 502. This makes it possible to reduce the number of parts and terminals. When a part or the whole of the pixel portion 502 is not formed on the same substrate, the driving circuit A part or the whole of the path portion 504 is COG or TAB (Tape Automated Band). It can be implemented by using the onding.

[0312] The pixel section 502 is arranged in X rows (X is a natural number of 2 or more) and Y columns (Y is a natural number of 2 or more). The display device has a circuit for driving a plurality of display elements (hereinafter, referred to as pixel circuit 501), The path section 504 is a circuit (hereinafter, a gate driver) that outputs a signal (scanning signal) for selecting a pixel. 504a) to provide a signal (data signal) for driving the display element of the pixel. The pixel circuit 504 includes a driver circuit such as a circuit (hereinafter, referred to as a source driver 504b).

[0313] The gate driver 504a includes a shift register and the like. A signal for driving the shift register is input via a terminal unit 507, and a signal is output. For example, a start pulse signal, a clock signal, etc. are input to the gate driver 504a. The gate driver 504a outputs a pulse signal. The gate has a function of controlling the potential of the scanning lines GL_1 to GL_X. A plurality of drivers 504a are provided, and the scanning lines GL_1 to Alternatively, the gate driver 504a may control the GL_X by dividing it. However, the gate driver 50 has a function of supplying 4a may also provide another signal.

[0314] The source driver 504b includes a shift register and the like. Through the terminal section 507, a signal for driving the shift register as well as a source of a data signal are input. The source driver 504b outputs a pixel circuit based on the image signal. The source driver 504b has a function of generating a data signal to be written to the source driver 501. A data signal is generated according to a pulse signal obtained by inputting a start pulse, a clock signal, etc. The source driver 504b has a function of controlling the output of a data signal. The data lines DL_1 to DL_Y are connected to the data line 101 through the data line 102. Alternatively, the source driver 504b may have a function of supplying an initialization signal. However, the present invention is not limited to this, and the source driver 504b may supply other signals. It is possible.

[0315] The source driver 504b is configured using, for example, a plurality of analog switches. The source driver 504b sequentially turns on a number of analog switches, A signal obtained by time-sharing an image signal can be output as a data signal.

[0316] Each of the plurality of pixel circuits 501 is connected to one of the plurality of scanning lines GL to which a scanning signal is applied. A pulse signal is inputted through the data line DL, and a data signal is given through one of the data lines DL. A data signal is input to each of the pixel circuits 501. 504a controls writing and holding of data of the data signal. For example, The second pixel circuit 501 is connected to a gate driver GL_m (where m is a natural number equal to or smaller than X) via a scanning line GL_m. A pulse signal is input from 504a, and the data line DL_n ( A data signal is input from the source driver 504b via a source driver 504c (n is a natural number equal to or smaller than Y).

[0317] The protection circuit 506 shown in FIG. 18A includes, for example, a gate driver 504a and a pixel circuit 5 01. Alternatively, the protection circuit 506 is connected to the scanning line GL, which is the wiring between the source driver The data line DL is connected between the driver 504b and the pixel circuit 501. The protection circuit 506 can be connected to a wiring between the gate driver 504a and the terminal unit 507. Alternatively, the protection circuit 506 may be a wiring between the source driver 504b and the terminal unit 507. The terminal unit 507 can be connected to a power supply and a power supply line from an external circuit to the display device. This refers to the part provided with terminals for inputting control signals and image signals.

[0318] When a potential outside a certain range is applied to the wiring to which the protection circuit 506 is connected, the protection circuit This is a circuit that brings one wire into electrical continuity with another wire.

[0319] As shown in FIG. 18A, a protection circuit 50 is provided in each of a pixel section 502 and a driver circuit section 504. 6, ESD (Electro Static Discharge: This can improve the resistance of the display device to overcurrent caused by electrostatic discharge (ESD) and the like. However, the configuration of the protection circuit 506 is not limited to this. For example, A configuration in which a protection circuit 506 is connected, or a protection circuit 506 is connected to the source driver 504b Alternatively, a protection circuit 506 may be connected to the terminal portion 507. It can also be written as:

[0320] In FIG. 18A, the gate driver 504a and the source driver 504b Therefore, although an example in which the driver circuit portion 504 is formed is shown, the present invention is not limited to this configuration. For example, only the gate driver 504a is formed, and a source driver circuit is formed separately. A substrate (for example, a drive circuit substrate formed of a single crystal semiconductor film or a polycrystalline semiconductor film) is It may also be configured to be equipped with

[0321] In addition, the pixel circuits 501 shown in FIG. 18(A) may have a configuration shown in FIG. 18(B), for example. It can be said that:

[0322] The pixel circuit 501 shown in FIG. 18B includes a liquid crystal element 570, a transistor 550, and a capacitor. The transistor 550 may be any of the transistors described in the previous embodiment. can be applied.

[0323] The potential of one of the pair of electrodes of the liquid crystal element 570 is appropriately set according to the specifications of the pixel circuit 501. The alignment state of the liquid crystal element 570 is set by the written data. A common potential is applied to one of a pair of electrodes of the liquid crystal element 570 in each of the pixel circuits 501. A common potential may be applied to the pair of liquid crystal elements 570 of the pixel circuits 501 in each row. A different potential may be applied to one of the electrodes.

[0324] For example, the display device including the liquid crystal element 570 can be driven in a TN mode, an STN mode, or the like. Mode, VA mode, ASM (Axially Symmetric Aligned M icro-cell mode, OCB (Optically Compensated Birefringence mode, FLC (Ferroelectric Liquid id Crystal) mode, AFLC (AntiFerroelectric Li quid Crystal) mode, MVA mode, PVA (Patterned Ve Vertical Alignment mode, IPS mode, FFS mode, or TBA (Transverse Bend Alignment) mode, etc. may also be used. In addition to the above-mentioned driving method, the display device can be driven by an ECB (Electric Carrier Bipolar Transistor) or the like. Ally Controlled Birefringence mode, PDLC(P Oligomeric Dispersed Liquid Crystal (PNLC) mode (Polymer Network Liquid Crystal) mode, guest hole However, there are various types of liquid crystal elements and their driving methods, and they are not limited to these. A variety of different types of sensors can be used.

[0325] In the pixel circuit 501 in the mth row and the nth column, One of the electrodes is electrically connected to the data line DL_n, and the other is a pair of electrodes of the liquid crystal element 570. The gate electrode of the transistor 550 is electrically connected to the other of the scan lines G L_m. The transistor 550 can be turned on or off. Thus, the write control circuit 100 has a function of controlling the writing of data of the data signal.

[0326] One of a pair of electrodes of the capacitor 560 is connected to a wiring to which a potential is supplied (hereinafter, a potential supply line VL ) and the other is electrically connected to the other of the pair of electrodes of the liquid crystal element 570. The value of the potential of the potential supply line VL is set appropriately according to the specifications of the pixel circuit 501. The capacitor 560 functions as a storage capacitor for storing written data.

[0327] For example, in a display device having the pixel circuit 501 shown in FIG. The pixel circuits 501 in each row are sequentially selected by a gate driver 504a shown in FIG. 550 is turned on to write data of the data signal.

[0328] In the pixel circuit 501 in which data has been written, the transistor 550 is turned off. By repeating this process row by row, an image can be displayed.

[0329] In addition, the pixel circuits 501 shown in FIG. 18(A) may be, for example, a configuration shown in FIG. It can be said that:

[0330] The pixel circuit 501 shown in FIG. 18C includes transistors 552 and 554 and a capacitance element. The transistor 552 and the transistor 554 The transistor described in the above embodiment can be used for either or both of the above. .

[0331] A data signal is applied to one of the source and drain electrodes of the transistor 552. The transistor 5 is electrically connected to a line (hereinafter, referred to as a data line DL_n). The gate electrode 52 is connected to a wiring (hereinafter, referred to as a scanning line GL_m) to which a gate signal is applied. are electrically connected.

[0332] Transistor 552 is turned on or off to transfer the data of the data signal. It has the function of controlling the writing of data.

[0333] One of a pair of electrodes of the capacitor 562 is connected to a wiring to which a potential is applied (hereinafter, a potential supply line VL _a), and the other is electrically connected to the source electrode and drain electrode of the transistor 552. The second electrode is electrically connected to the other of the first and second electrodes.

[0334] The capacitor 562 functions as a storage capacitor for storing written data.

[0335] One of the source electrode and the drain electrode of the transistor 554 is connected to the potential supply line VL_a. In addition, the gate electrode of the transistor 554 is electrically connected to the It is electrically connected to the other of the source electrode and the drain electrode.

[0336] One of the anode and the cathode of the light-emitting element 572 is electrically connected to the potential supply line VL_b. The other one is electrically connected to the other of the source electrode and drain electrode of the transistor 554. will be done.

[0337] The light-emitting element 572 may be, for example, an organic electroluminescence element (also called an organic EL element). However, the light-emitting element 572 is not limited to this. Alternatively, an inorganic EL element made of an inorganic material may be used.

[0338] A high power supply potential VDD is applied to one of the potential supply lines VL_a and VL_b. and the other is supplied with a low power supply potential VSS.

[0339] In a display device having the pixel circuit 501 shown in FIG. 18C, for example, The pixel circuits 501 in each row are sequentially selected by the gate driver 504a, and the transistors 552 are turned on. The data signal is written by turning it on.

[0340] In the pixel circuit 501 to which the data has been written, the transistor 552 is turned off. Furthermore, the transistor 554 is in a holding state in response to the potential of the written data signal. The amount of current flowing between the source electrode and the drain electrode is controlled, and the light emitting element 572 The light is emitted with a brightness that corresponds to the flow rate. By performing this process row by row, an image can be displayed.

[0341] The structure described in this embodiment may be used in appropriate combination with structures described in other embodiments. can be done.

[0342] (Embodiment 5) In this embodiment, a display module and an electronic device each including a semiconductor device according to one embodiment of the present invention will be described. This will be described with reference to FIG. 19 and FIG. 20.

[0343] The display module 8000 shown in FIG. 19 includes an upper cover 8001 and a lower cover 8002. Between them, touch panel 8004 connected to FPC8003, A display panel 8006, a backlight 8007, a frame 8009, and a printed circuit board 801 0, has battery 8011.

[0344] The semiconductor device of one embodiment of the present invention can be used for the display panel 8006, for example.

[0345] The upper cover 8001 and the lower cover 8002 are connected to the touch panel 8004 and the display panel The shape and dimensions can be changed as appropriate to match the size of 8006.

[0346] The touch panel 8004 is a resistive or capacitive touch panel. The display panel 8006 can be used by overlapping it with the opposing substrate (sealing substrate). It is also possible to provide the display panel 8 with a touch panel function. It is also possible to provide an optical sensor in each pixel of the display panel 006 to make it into an optical touch panel.

[0347] The backlight 8007 has a light source 8008. In FIG. In the above embodiment, the light source 8008 is disposed on the light source 8007, but the present invention is not limited to this. For example, a light source 8008 is arranged at the end of a backlight 8007, and a light diffusion plate is further used. In addition, when a self-luminous light-emitting element such as an organic EL element is used, or when a reflective In the case of a flat panel or the like, the backlight 8007 need not be provided.

[0348] The frame 8009 protects the display panel 8006 and also supports the movement of the printed circuit board 8010. It also functions as an electromagnetic shield to block electromagnetic waves generated by the operation of the frame. The frame 8009 may also function as a heat sink.

[0349] The printed circuit board 8010 includes a power supply circuit, a signal circuit for outputting a video signal, and a clock signal. The power supply circuit is provided with a signal processing circuit. Alternatively, the power source may be a battery 8011 provided separately. , this can be omitted when using a commercial power source.

[0350] In addition, the display module 8000 includes components such as a polarizing plate, a retardation plate, and a prism sheet. It may be added.

[0351] 20(A) to 20(G) are diagrams showing electronic devices. These electronic devices are A body 9000, a display unit 9001, a speaker 9003, and operation keys 9005 (power switch, etc.) includes an operation switch), a connection terminal 9006, a sensor 9007 (force, displacement, position, speed, Acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electricity Measures field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays The device may have a built-in microphone 9008, etc.

[0352] The electronic devices illustrated in FIGS. 20A to 20G can have various functions. For example, the function to display various information (still images, videos, text images, etc.) on the display, Panel function, calendar, date or time display function, various software ( A function to control processing by a program, wireless communication function, and various functions using wireless communication function Functions for connecting to computer networks, transmitting various data using wireless communication functions, or receiving the program or data recorded on the recording medium, and displaying the program or data. The display unit may have a function of displaying the information on the display unit. The functions that the electronic device shown in the figure can have are not limited to these, and the electronic device may have a variety of functions. Although not shown in FIG. 20(A) to FIG. 20(G), the electronic device may include The electronic device may have a plurality of display units. The function to take pictures, record videos, and store the images on a recording medium (external or built-in to the camera) ) and a function for displaying the captured image on a display unit.

[0353] The electronic devices shown in FIGS. 20A to 20G will be described in detail below.

[0354] FIG. 20A is a perspective view showing a portable information terminal 9100. The display unit 9001 has flexibility. The display unit 9001 can be incorporated along the screen. The device is equipped with a touch sensor, and can be operated by touching the screen with a finger or a stylus. By touching the icon displayed on the display 9001, the application can be started. can.

[0355] FIG. 20B is a perspective view showing a portable information terminal 9101. For example, the device has one or more functions selected from a telephone, a notebook, an information viewing device, etc. Specifically, the mobile information terminal 9101 can be used as a smartphone. Although the speaker 9003, the connection terminal 9006, the sensor 9007, etc. are omitted in the figure, The mobile information terminal 9100 shown in FIG. 20(A) can be installed in the same position. The information terminal 9101 can display text and image information on multiple surfaces. For example, Three operation buttons 9050 (also called operation icons or simply icons) are displayed on the display unit 900. The information 9051 shown in the dashed rectangle can be displayed on one side of the display unit 90. 01. An example of the information 9051 is an e-mail Displays to notify you of incoming calls, SNS (social networking services), etc. , subject of email or SNS, sender name of email or SNS, date and time, time, Battery level, antenna reception strength, etc. Or, information 9051 is displayed. Instead of the information 9051, an operation button 9050 or the like may be displayed at that position.

[0356] FIG. 20C is a perspective view showing a portable information terminal 9102. , and has a function of displaying information on three or more faces of the display unit 9001. An example is shown in which information 9053 and information 9054 are displayed on different sides. The user of the portable information terminal 9102 holds the portable information terminal 9102 in the breast pocket of the clothes. In this state, the display (information 9053 in this case) can be confirmed. The telephone number or name of the caller is displayed on the mobile information terminal 9102 so that it can be observed from above. The user can read the display without taking the mobile information terminal 9102 out of his pocket. You can check the number and decide whether to answer the call or not.

[0357] 20(D) is a perspective view showing a wristwatch-type portable information terminal 9200. The 9200 is used for mobile phone calls, e-mail, document browsing and writing, music playback, and Internet communications. It is possible to execute various applications such as computer games. The display unit 9001 has a curved display surface, and displays information along the curved display surface. In addition, the portable information terminal 9200 can perform short-distance wireless communication according to a communication standard. For example, by communicating with a wireless headset, The mobile information terminal 9200 also has a connection terminal 9006. It has a connector and can directly exchange data with other information terminals. Charging can also be performed via the connection terminal 9006. Power may also be supplied wirelessly without going through 6.

[0358] 20(E), (F), and (G) are perspective views showing a foldable portable information terminal 9201. FIG. 20E is a perspective view of the portable information terminal 9201 in an unfolded state. (F) shows the mobile information terminal 9201 being changed from one of the unfolded and folded states to the other. FIG. 20(G) is a perspective view of the portable information terminal 9201 in a folded state. The portable information terminal 9201 is highly portable when folded and is unfolded. When the display is turned on, the seamless, wide display area provides excellent visibility of the display. The display unit 9001 of the display device 9001 is made up of three housings 9000 connected by hinges 9055. The two housings 9000 are supported by the hinge 9055. The portable information terminal 9201 can be reversibly transformed from an unfolded state to a folded state. For example, the portable information terminal 9201 can be bent with a radius of curvature of 1 mm or more and 150 mm or less. It can be done.

[0359] The electronic device described in this embodiment has a display unit for displaying some information. However, the semiconductor device of one embodiment of the present invention is an electronic device that does not have a display portion. The present invention can also be applied to the display unit of the electronic device described in this embodiment. In the case of a display device, the display device may be flexible and capable of displaying information along a curved display surface, or may be folded. Although a foldable display unit has been exemplified, the present invention is not limited to this. A display may be provided on the surface.

[0360] The structure described in this embodiment may be used in appropriate combination with structures described in other embodiments. can be done. EXAMPLES

[0361] In this embodiment, the analytical sample 600 shown in FIG. 21(A) and the A transistor 650 shown in FIG. 1 was fabricated, and a SIMS analysis of an analysis sample 600 and a The electrical characteristics of Transistor 650 were measured.

[0362] 21B and 21C are top views of the transistor 650 shown in FIG. FIG. 21B is a top view of the transistor 170. FIG. 21(C) is a cross-sectional view of the transistor 650 in the channel length direction. 1 is a cross-sectional view in the channel width direction.

[0363] In this embodiment, the following sample B1 and sample B2 were used as the analysis sample 600. Sample B2 was prepared. Samples C1 and C2 were prepared as the transistor 650. Sample B1 and Sample C1 are semiconductor devices according to one embodiment of the present invention. Samples B2 and C2 are comparative semiconductor devices.

[0364] First, the method for producing the analysis sample 600 produced in this embodiment will be described below. .

[0365] (Sample B1 and Sample B2) First, a conductive film was formed on a substrate 602, and then the conductive film was removed. A glass substrate was used for the conductive film. The conductive film was formed by using a sputtering apparatus. An etching device was used.

[0366] Next, insulating films 606 and 607 were formed on the substrate 602. The insulating film 606 had a thickness of A 400 nm silicon nitride film was formed using a PECVD apparatus. As the thin film, a silicon oxynitride film having a thickness of 50 nm was formed using a PECVD apparatus.

[0367] Next, an oxide semiconductor film 608a was formed over the insulating film 607. The formation conditions of the oxide semiconductor film 608a are different from those in Example 2.

[0368] The oxide semiconductor film 608a of the sample B1 was an IGZO film having a thickness of 35 nm, which was formed by sputtering. The oxide semiconductor film 608a of Sample B1 was formed using a ring apparatus. The substrate temperature was set at 170° C., and argon gas with a flow rate of 100 sccm and cm of oxygen gas was introduced into the chamber, and the pressure was set to 0.6 Pa. A 2500W laser was used on a polycrystalline target (In:Ga:Zn=1:1:1.2 [atomic ratio]). The film was formed by applying an AC power of 1000 W.

[0369] The oxide semiconductor film 608a of the sample B2 was an IGZO film having a thickness of 35 nm, which was formed by sputtering. The oxide semiconductor film 608a of Sample B2 was formed using a ring apparatus. The substrate temperature was set at 170° C., and argon gas with a flow rate of 100 sccm and cm of oxygen gas was introduced into the chamber, and the pressure was set to 0.6 Pa. A 2500W A was applied to the polycrystalline target (In:Ga:Zn=1:1:1 [atomic ratio]). C power was applied to form a film.

[0370] Next, the first heat treatment was carried out. The first heat treatment was carried out at 450° C. under a nitrogen atmosphere. Heat treatment for 1 hour at 450℃ in a nitrogen and oxygen mixed gas atmosphere. It was decided.

[0371] Next, a conductive film is formed over the insulating film 607 and the oxide semiconductor film 608a. The conductive film was a 50 nm thick tungsten film and a 400 nm thick tungsten film. A 100 nm thick aluminum film and a 100 nm thick titanium film were deposited in a vacuum using a sputtering device. The conductive film was removed by a dry etching device. Ta.

[0372] Next, a chemical solution is applied onto the oxide semiconductor film 608a. The washing method was as follows: 100 times the amount of 85% phosphoric acid solution was used. The diluted solution was applied to the oxide semiconductor film 608a, and then washed for 15 seconds.

[0373] Next, the insulating film 614 and the insulating film 616 were formed over the oxide semiconductor film 608a. As the substrate 614, a silicon oxynitride film having a thickness of 50 nm is formed using a PECVD apparatus. The insulating film 616 is a silicon oxynitride film having a thickness of 400 nm, which is formed by PECVD. The insulating film 614 and the insulating film 616 were formed using a PECVD apparatus. The layers were then successively formed in a vacuum.

[0374] The conditions for forming the insulating film 614 were a substrate temperature of 220° C. and a silica gel flow rate of 50 sccm. Nitrous oxide gas at a flow rate of 2000 sccm was introduced into the chamber, and the pressure was increased to 2 The pressure was set to 0 Pa, and 100 W of RF power was applied between the parallel plate electrodes installed in the PECVD device. The insulating film 616 was formed under the conditions of a substrate temperature of 220° C. and a flow rate of 1000 μm. Silane gas at a flow rate of 160 sccm and nitrous oxide gas at a flow rate of 4000 sccm were introduced into the chamber. The pressure was set to 200 Pa, and the gas was placed between the parallel plate electrodes in the PECVD device. An RF power of 1500 W was supplied to the substrate to form the film.

[0375] Next, a second heat treatment was performed in a mixed gas atmosphere of nitrogen and oxygen. The mixture was heated at 350°C for 1 hour.

[0376] Next, after the second heat treatment, the following three steps were carried out only on sample B1.

[0377] <1, ITSO film formation process> An ITSO film having a thickness of 5 nm was formed on the insulating film 616 by using a sputtering apparatus. The composition of the target used for the ITSO film was In2O3:SnO2:SiO 2 = 85:10:5 [weight %].

[0378] <2. Oxygen addition process> Next, oxygen was added to the ITSO film. Using this device, oxygen gas was introduced into the chamber at a flow rate of 250 sccm and the pressure was set to 15 Pa. A parallel plate electrode is installed in the ashing device so that a bias is applied to the substrate side. An RF power of 4500 W was supplied between the electrodes.

[0379] <3. ITSO film removal process> Next, the ITSO film was removed to expose the insulating film 616. In this case, a wet etching apparatus is used to apply a 5% oxalic acid solution onto the insulating film 616. After etching for 300 seconds, 0.5% hydrofluoric acid was applied to the insulating film 61 The coating was applied onto 6 and etched for 15 seconds.

[0380] Next, in both samples B1 and B2, an insulating film 618 was formed on the insulating film 616. As the film 618, a silicon nitride film having a thickness of 100 nm is formed using a PECVD apparatus. The insulating film 618 was formed under the conditions of a substrate temperature of 350° C. and a flow rate of 50 sccm. Run gas, nitrogen gas with a flow rate of 5000 sccm, and ammonia gas with a flow rate of 100 sccm The pressure was set to 100 Pa, and the parallel flat plate installed in the PECVD device was The film was deposited by supplying 1000 W of RF power between the electrodes of the plate.

[0381] Next, a third heat treatment was performed. The third heat treatment was performed at 250° C. under a nitrogen atmosphere. The time was.

[0382] Through the above steps, samples B1 and B2 of this example were fabricated.

[0383] Next, the oxide semiconductor film 608a and the insulating films 614 and 6 SIMS analysis was performed to measure the indium concentration in the 16,618 film. The analytical results of sample B1 are shown in FIG. 22(A), and the analytical results of sample B2 are shown in FIG. 22(B). In FIG. 22(A) and (B), the horizontal axis represents the depth (nm) and the vertical axis represents the indium concentration (a toms / cm 3 ), respectively.

[0384] From the results shown in FIGS. 22(A) and 22(B), it is clear that the sample B1 has a high thermal conductivity at the interface between the insulating film 616 and the insulating film 618. There is 5×10 indium near the surface. 16 atoms / cm 3 It was confirmed at concentrations above 100. In the sample B2, indium was present in the vicinity of the interface between the insulating film 616 and the insulating film 618. 16 atoms / cm 3 In the above SIMS analysis, the indium The lower limit is 1×10 15 atoms / cm 3 The following is the result.

[0385] In addition, when comparing sample B1 and sample B2, the insulating film 616 and the insulating film 618 of sample B1 are The amount of indium detected near the interface between the insulating film 616 and the insulating film 618 of sample B2 was This is greater than the amount of indium detected nearby.

[0386] From the results shown in FIG. 22(A) and (B), it is clear that sample B1 has a function of suppressing oxygen release. The indium in the ITSO film used as a functional film was converted to the insulating film 61 during the oxygen addition treatment. 6, indium was detected near the interface between the insulating film 616 and the insulating film 618. On the other hand, in the sample B2, the ITSO film formation process and the oxygen addition process were performed on the insulating film 616. Since the treatment process and the ITSO film removal process are not performed, the surface of the insulating film 616, in other words, As a result, no indium was detected near the interface between the insulating film 616 and the insulating film 618 .

[0387] Since the insulating film 616 contains oxygen, when the insulating film 616 contains excess oxygen, Even in such cases, oxygen, one of the main components, may not be accurately measured by SIMS analysis. For example, even if the insulating film 616 contains oxygen exceeding the stoichiometric composition, In SIMS analysis, it can be difficult to measure oxygen above the stoichiometric composition. However, as shown in the semiconductor device of one embodiment of the present invention, oxygen is released onto the insulating film 616. An ITSO film is formed as a film having a function of suppressing outflow, and an insulating film is formed through the ITSO film. When oxygen is added to the insulating film 616, as shown in FIG. In other words, indium is detected near the interface between the insulating film 616 and the insulating film 618. Therefore, in order to confirm whether a step of adding oxygen to the insulating film 616 has been performed, This can be confirmed by measuring the impurity concentration near the surface of the film 616, here the indium concentration. There are cases.

[0388] As described above, oxygen in the insulating film 616 cannot be accurately measured by SIMS analysis. In this case, the physical properties of the film in contact with the insulating film 616, It is important to analyze the indium concentration near the interface with 8.

[0389] Next, a method for manufacturing the transistor 650 according to this embodiment will be described below.

[0390] (Sample C1 and Sample C2) For samples C1 and C2, the channel length L was 3 μm and the channel width W was 50 μm in the substrate. Five transistors of μm size were fabricated.

[0391] First, a conductive film is formed on a substrate 602, and then the conductive film is processed to form a conductive film 604. As the conductive film 604, a tungsten film having a thickness of 100 nm was deposited by a sputtering apparatus. It was formed using.

[0392] Next, insulating films 606 and 607 are formed over the substrate 602 and the conductive film 604 .

[0393] Next, an oxide semiconductor film 608a is formed over the insulating film 607. The oxide semiconductor film 608 was formed by processing the oxide semiconductor film into an island shape. The formation conditions of the oxide semiconductor film 608 are different.

[0394] The oxide semiconductor film 608 of Sample C1 was the oxide semiconductor film 608 of Sample B1 described above. After being formed under the same conditions as in a, it was processed into an island shape.

[0395] The oxide semiconductor film 608 of Sample C2 was the oxide semiconductor film After being formed under the same conditions as 608a, it was processed into an island shape.

[0396] Next, a first heat treatment was carried out.

[0397] Next, a conductive film is formed over the insulating film 607 and the oxide semiconductor film 608 and processed. The conductive films 612a and 612b were formed by the above process. A tungsten film with a thickness of 50 nm, an aluminum film with a thickness of 400 nm, and a 100 nm The titanium film was formed in succession in a vacuum using a sputtering apparatus.

[0398] Next, the insulating film 614 and the insulating layer 615 are formed over the oxide semiconductor film 608 and the conductive films 612a and 612b. A velum 616 was formed.

[0399] Next, a second heat treatment was performed.

[0400] Next, the sample C1 was subjected to the ITSO film formation process and the oxygen addition process in the same manner as the sample B1 described above. The ITSO film removal process was performed for sample C2, similar to sample B2 described above. The TSO film formation step, the oxygen addition treatment step, and the ITSO film removal step were not performed.

[0401] Next, an insulating film 618 was formed on the insulating film 616 .

[0402] Next, an opening 642c reaching the conductive film 612b and an opening 642b reaching the conductive film 604 are formed. The openings 642a, 642b, and 642c were formed by dry etching. The film was formed using a mixing apparatus.

[0403] Next, a conductive film is formed on the insulating film 618 so as to cover the openings 642a, 642b, and 642c. The conductive film was processed to form conductive films 620a and 620b. , 620b is a 100 nm thick ITSO film formed using a sputtering device. The composition of the target used for the ITSO film was the same as that used in the ITSO film formation process described above. The composition was the same as that of the

[0404] Next, a third heat treatment was performed.

[0405] Through the above steps, samples C1 and C2 were fabricated.

[0406] Next, the electrical characteristics of the transistors of Samples C1 and C2 prepared above were measured. The electrical characteristics of 1 and C2 are shown in Figures 23(A) and (B).

[0407] FIG. 23A shows the electrical characteristics of sample C1, and FIG. 23B shows the electrical characteristics of sample C2. The electrical characteristics are shown in Fig. 23(A) and (B). The horizontal axis indicates the gate voltage (Vg). The vertical axis represents the drain current (Id), and the data for five transistors are superimposed. The voltage between the source and drain electrodes (Vd) is 1 V and 10 V. , Vg was applied from −15 V to 20 V in 0.5 V intervals.

[0408] From the results shown in FIGS. 23(A) and 23(B), it can be seen that in the sample C1 according to one embodiment of the present invention, multiple It can be seen that there is little variation in the transistor. On the other hand, in the comparative sample C2, It is confirmed that there is a large variation in the characteristics of multiple transistors. It was confirmed that the transistor characteristics were normally on.

[0409] The difference in the transistor characteristics between the above-mentioned samples C1 and C2 is that the insulating films 614 and 616 are formed with oxygen. It is suggested that this is due to the presence or absence of a heat treatment process. An ITSO film is formed on the insulating film 614 and 616, and oxygen is added to the insulating films 614 and 616 through the ITSO film. This suggests that excess oxygen can be suitably added to the insulating films 614 and 616. In addition, the excess oxygen compensates for oxygen vacancies in the oxide semiconductor film 608. It is suggested that a transistor with little variation and good start-up characteristics was formed. can be.

[0410] From the above, the transistor of the sample C1 of this embodiment has little variation and is highly reliable. It was shown that this is a high-performance transistor.

[0411] The configuration shown in this embodiment can be used in appropriate combination with other embodiments. . [Explanation of symbols]

[0412] 100 Transistors 100A Transistor 100B Transistor 102 Substrate 104 Conductive film 106 Insulating film 107 Insulating film 108 Oxide semiconductor film 108a Oxide semiconductor film 108b Oxide semiconductor film 108c Oxide semiconductor film 112a Conductive film 112b Conductive film 114 Insulating film 116 Insulating film 117 Oxide Semiconductor Film 118 Insulating film 120 Conductive film 120a Conductive film 120b Conductive film 130 membrane 139 Oxygen 141a opening 141b opening 142 Etchant 142a opening 142b opening 142c opening 150 Transistors 160 Transistors 170 Transistors 180b Oxide semiconductor film 200 Semiconductor device 202 Substrate 204 Insulating film 206 Insulating Film 230 membrane 239 Oxygen 242 Etchant 501 Pixel circuit 502 Pixel section 504 Drive circuit section 504a Gate Driver 504b source driver 506 Protection circuit 507 Terminal section 550 Transistor 552 Transistor 554 Transistor 560 Capacitive element 562 Capacitive element 570 Liquid crystal element 572 Light emitting element 600 Analytical Samples 602 Substrate 604 Conductive film 606 Insulating film 607 Insulating film 608 Oxide Semiconductor Film 608a Oxide semiconductor film 612a Conductive film 612b Conductive film 614 Insulating film 616 Insulating film 618 Insulating film 620a Conductive film 620b Conductive film 642a opening 642b opening 642c opening 650 Transistors 700 Display device 701 Substrate 702 Pixel section 704 Source driver circuit section 705 Substrate 706 Gate driver circuit section 708 FPC terminal section 710 Signal Line 711 Wiring section 712 Sealing material 716 FPC 730 Insulating film 732 Sealing film 734 Insulating film 736 Colored film 738 Light-shielding film 750 Transistors 752 Transistor 760 Connection electrode 764 Insulating film 766 Insulating Film 767 Oxide Semiconductor Film 768 Insulating Film 770 Planarizing Insulating Film 772 Conductive Film 774 Conductive Film 775 Liquid crystal elements 776 Liquid crystal layer 778 Structure 780 Anisotropic Conductive Film 782 Light emitting element 784 Conductive Film 786 EL layer 788 Conductive Film 790 Capacitive element 8000 Display Module 8001 Top cover 8002 Lower cover 8003 FPC 8004 Touch Panel 8005 FPC 8006 Display Panel 8007 Backlight 8008 light source 8009 Frame 8010 Printed Circuit Board 8011 Battery 9000 Chassis 9001 Display section 9003 Speaker 9005 Operation key 9006 Connection terminal 9007 Sensor 9008 Microphone 9050 Operation button 9051 Information 9052 Information 9053 Information 9054 Information 9055 Hinge 9100 Mobile Information Terminal 9101 Portable information terminal 9102 Portable information terminal 9200 Mobile Information Terminal 9201 Portable information terminals

Claims

1. A first insulating film; an oxide semiconductor film having a region located above the first insulating film; a second insulating film having a region located above the oxide semiconductor film; a third insulating film having a region located above the second insulating film; the second insulating film has a first region and a second region having a region located above the first region, the third insulating film has a third region and a fourth region having a region located above the third region, the indium concentration in the first region is lower than the indium concentration in the second region; The semiconductor device, wherein the indium concentration in the third region is lower than the indium concentration in the fourth region.

2. A gate electrode; a first insulating film having a region located above the gate electrode; an oxide semiconductor film having a region located above the first insulating film; a source electrode electrically connected to the oxide semiconductor film; a drain electrode electrically connected to the oxide semiconductor film; a second insulating film on the oxide semiconductor film, the source electrode, and the drain electrode; a third insulating film having a region located above the second insulating film; the second insulating film has a first region and a second region having a region located above the first region, the third insulating film has a third region and a fourth region having a region located above the third region, the indium concentration in the first region is lower than the indium concentration in the second region; The semiconductor device, wherein the indium concentration in the third region is lower than the indium concentration in the fourth region.

3. In claim 1 or 2, The oxide semiconductor film is A semiconductor device comprising: oxygen, In, Zn, and M (M is Ti, Ga, Sn, Y, Zr, La, Ce, Nd, or Hf).

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