JP2006351613A - FIELD EFFECT TRANSISTOR, ITS MANUFACTURING METHOD, AND ELECTRONIC DEVICE - Google Patents

Abstract

A field effect transistor having high mobility, good contact between an electrode and a semiconductor and less variation in characteristics, a method for manufacturing the field effect transistor, and an electronic device using the transistor at least in part.
A field effect transistor including a source electrode, a drain electrode, a gate electrode, and a needle-shaped semiconductor, wherein the needle-shaped semiconductor is formed into a conductive polymer in the source electrode and the drain electrode. A field-effect transistor that is covered and in which a needle-like semiconductor 26 is covered with an insulating polymer in a channel portion 25.
[Selection] Figure 2

Description

  The present invention relates to a field effect transistor using a needle-shaped semiconductor, a manufacturing method thereof, and an electronic apparatus using the field effect transistor.

In recent years, with the speeding up of information processing and communication, etc., the mobility of a needle-shaped semiconductor such as carbon nanotube (hereinafter abbreviated as CNT) or silicon nanowire in the channel region formed between the source electrode and the drain electrode is increased. Research into large field effect transistors is ongoing. FIG. 1 shows the structure of a conventional field effect transistor using typical CNTs. As shown in FIG. 1, an oxide film (100 to 500 nm) which is a gate insulating film 12 is formed on a glass substrate 10, and a source electrode 13 and a drain electrode 14 made of gold or platinum are formed thereon, and an organic solvent The semiconductor layer 15 is formed by applying CNTs diluted and dispersed in CNTs and CNTs straddling the electrodes. (See Patent Document 1)
JP 2004-071654 A

  However, in a field effect transistor manufactured by dropping a solvent between the source electrode and the drain electrode and removing the solvent, the contact between the CNT and the source electrode and the drain electrode is only the portion where the CNT and the electrode are in contact with each other. Poor contact between electrodes and large variation in characteristics.

  The present invention has been made to solve such a problem. A field effect transistor having high mobility using a needle-shaped semiconductor having good contact property, a method for manufacturing the same, and at least one of the field effect transistors are provided. It is an object of the present invention to provide an electronic device used for a part.

  The field effect transistor of the present invention is a field effect transistor comprising a source electrode, a drain electrode, a gate electrode, and a needle-like semiconductor, wherein the needle-like semiconductor is covered with a conductive polymer in the source electrode and the drain electrode. The needle-like semiconductor is covered with an insulating polymer in a channel portion connecting the source electrode and the drain electrode. Thereby, it is possible to realize a field effect transistor having a good contact property between the electrode and the needle-like semiconductor.

  Furthermore, the length of the acicular semiconductor is preferably longer than the channel length. As a result, since the source electrode and the drain electrode can be connected by a single needle-like semiconductor, a field effect transistor with high mobility can be realized without requiring hopping conduction between molecules. That is, an electric field having a higher mobility than the case where a plurality of needle-like semiconductors having a length shorter than the length between the source and drain electrodes is aligned and connected in series to connect the source-drain electrodes with the needle-like semiconductor. An effect transistor is feasible and preferable.

  Furthermore, it is preferable that the acicular semiconductor is oriented substantially parallel to the direction connecting the source electrode and the drain electrode. Thereby, the acicular semiconductor which connects a source electrode and a drain electrode increases, and the field effect transistor which can obtain a high electric current stably is realizable. That is, since the needle-shaped semiconductor that is not substantially parallel to the direction connecting the source electrode and the drain electrode and is oriented in a direction with a large angle increases the probability that the source-drain electrode cannot be connected, It is preferable that the number of semiconductors that are substantially aligned in the parallel direction increases the number of needle-shaped semiconductors that connect the source electrode and the drain electrode, and a field effect transistor that can stably obtain a high current can be realized.

  The electronic device of the present invention is an electronic device including at least one semiconductor element, wherein at least one of the semiconductor elements is the field effect transistor described above. By using an electronic device including a field effect transistor with high mobility, an electronic device with improved response speed such as response speed and processing speed is provided. In addition, the needle-like semiconductor field effect transistor can be easily formed directly on the electronic device, and can be downsized, so that the electronic device can be downsized, the transistors of the present invention can be arranged at a higher density, and the higher It is also preferable to provide a high-performance electronic device.

  The electronic device is preferably an active matrix display.

  The field effect transistor of the present invention having high mobility and small characteristic variation can be easily and stably formed on a member constituting an active matrix display, and an active matrix display can be formed using the field effect transistor. By configuring, a display with high characteristics and low cost can be obtained. Further, by using the field effect transistor of the present invention, the field effect transistor can be miniaturized and a light and flexible plastic substrate (film-like plastic substrate) can be used. A sheet-like display can be realized. In addition, an improvement in mobility makes it possible to obtain an active matrix display with a high display speed (reaction speed).

  As the electronic device, it is preferable that the electronic device is a wireless ID tag. By using the field effect transistor of the present invention, the field effect transistor can be miniaturized and can be attached to articles of various materials, so that wireless ID tags having various shapes can be easily provided. Further, by using the field effect transistor of the present invention having high mobility, a wireless ID tag having a high reaction speed (processing speed) and a high communication frequency can be obtained.

  Moreover, as said electronic device, it is preferable that the said electronic device is a portable apparatus.

  By using the field effect transistor of the present invention for at least a part of the elements of these portable devices, the field effect transistor can be miniaturized, and a considerable part can be made of an organic material such as plastic, so that it is mechanical. Portable devices having the advantages of organic materials such as flexibility, impact resistance, environmental resistance when discarded, light weight, and low cost can also be manufactured.

  The field effect transistor manufacturing method of the present invention includes a source electrode, a drain electrode, a gate electrode, and a source electrode, a drain electrode, and a field effect transistor including a needle-like semiconductor in a channel portion connecting between the source electrode and the drain electrode. In the manufacturing method, the portion for forming the source electrode, the drain electrode, and the channel portion is formed of an insulating polymer and a needle-shaped semiconductor mixed layer, and then a part of the insulating polymer and the needle-shaped semiconductor mixed layer is insulated. The source electrode and the drain electrode are formed by converting a polymer into a conductive polymer. As a result, the surroundings of the needle-like semiconductor in the vicinity of the source electrode and the drain electrode are all covered with the conductive polymer, the contact property between the electrode and the needle-like semiconductor is good, the mobility is large, and the electric field with little characteristic variation is obtained. An effect transistor can be realized.

  In addition, another field effect transistor manufacturing method of the present invention includes a source electrode, a drain electrode, a gate electrode, and a field effect including a needle-like semiconductor in the source electrode, the drain electrode, and a channel portion connected therebetween. A method for manufacturing a transistor, wherein the source electrode, the drain electrode, and a portion for forming a channel portion are formed of a conductive polymer and a needle-shaped semiconductor mixed layer, and then a part of the conductive polymer and the needle-shaped semiconductor mixed layer is formed. A channel portion is formed by converting a conductive polymer into an insulating polymer. As a result, the surroundings of the needle-like semiconductor in the vicinity of the source electrode and the drain electrode are all covered with the conductive polymer, the contact property between the electrode and the needle-like semiconductor is good, the mobility is large, and the electric field with little characteristic variation is obtained. An effect transistor can be realized.

  According to the present invention, it is possible to provide a field effect transistor using an acicular semiconductor with high mobility and little characteristic variation, and an easy manufacturing method thereof.

  In addition, in an electronic device using at least a part of the field effect transistor of the present invention, an electronic device with improved response speed such as response speed and processing speed is provided. In addition, the field effect transistor of the present invention can be miniaturized, and a considerable part can be made of an organic material such as plastic. Therefore, mechanical flexibility, impact resistance, environmental resistance when throwing away, light weight, and low cost. It is also possible to manufacture portable devices that have the advantage of organic materials such as excellent characteristics.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 2 is an example of a cross-sectional view of a field effect transistor using a needle-like semiconductor according to this embodiment. In the field effect transistor shown in FIG. 2, a gate electrode 21 is formed on a substrate 20, and a gate insulating film 22 is formed to cover the gate electrode 21. On the gate insulating film 22, a source electrode 23 and a drain electrode 24, and a channel region 25 are formed at regular intervals. At this time, the acicular semiconductor 26 is included in the source electrode 23, the drain electrode 24, and the channel region 25.

  Although the material which comprises the board | substrate 20 is not restrict | limited in particular, For example, insulating materials, such as inorganic materials, such as glass, quartz, an alumina sintered compact, plastics, such as a polyimide film and a polyester film, etc. are used. In particular, a plastic substrate is suitable when importance is attached to mechanical flexibility, impact resistance, lightness, and the like. The thickness of the substrate is not particularly limited, but a substrate in the range of 5 to 200 nm is convenient from the viewpoint of miniaturization and thinning.

  The gate electrode 21 is made of, for example, an inorganic material such as gold, platinum, silver, copper, aluminum, chromium, molybdenum, nickel, alloys thereof, polysilicon, amorphous silicon, or ITO (indium-tin oxide). May be. These conductive materials may be formed into a film thickness of about 50 to 500 nm by a vapor deposition method, a sputtering method, or the like, and may be processed into a desired shape by a normal photolithography process and an etching process. Alternatively, a conductive organic material may be used. The conductive organic material may be formed by printing by an inkjet method. Examples of the conductive organic material include polyaniline and polyethylenedioxythiophene / polystyrene sulfonic acid (hereinafter abbreviated as PEDOT / PSS).

The gate insulating film 22 may be formed of an inorganic insulating material such as SiO ₂ or Al ₂ O _3, or an organic insulating material such as polyacrylonitrile, polychloropyrene, polyethylene terephthalate, polyoxymethylene, polycarbonate, or polyimide. These insulating films are formed to a thickness of about 50 nm to 1000 nm by a CVD method, a spin coat method, a cast method, a vapor deposition method, or the like.

  The source electrode 23, the drain electrode 24, and the channel region 25 can be manufactured using a conductive polymer and a needle-shaped semiconductor composite material as a starting raw material (however, an insulating polymer is used instead of a conductive polymer as a starting raw material). Example 1 described later shows an example in which an insulating polymer is used as a starting material in the structure of Embodiment 1). First, a conductive polymer and a needle-shaped semiconductor composite layer are formed on the gate insulating film 22 in portions to be the channel region 25, the source electrode 23, and the drain electrode 24. This conductive polymer and acicular semiconductor composite layer can be formed by using a mixed liquid of a conductive polymer and acicular semiconductor by using an inkjet method, a dip coating method, a spin coating method, etc. It is not limited to. For adjusting the mixed liquid of the conductive polymer and the needle-shaped semiconductor, for example, an organic solvent that dissolves the conductive polymer but does not dissolve the needle-shaped semiconductor is used as the solvent. Such an organic solvent varies depending on the conductive polymer used and the needle-shaped semiconductor, and thus cannot be defined in general. Examples thereof include organic solvents such as chloroform and dimethylformamide (hereinafter abbreviated as DMF).

  Next, the channel region 25, the source electrode 23, and the drain electrode 24 can be formed by converting the conductivity of the polymer in the channel region 25 into an insulating property. As a method for converting the conductivity of a polymer, a method of changing the doping amount of an additive for making it conductive, a method of changing the phase from crystal to amorphous by applying heat, a method of changing the orientation direction of molecules and crystals Are exemplified, but not limited to these.

  As a conductive polymer material, it is an organic material which shows electroconductivity, and can use a well-known organic molecule. Examples thereof include polypyrrole, polyphenylene, polythiophene, polyphenylene vinylene, polyaniline and the like to which an oxidizing agent and a reducing agent are added, but are not particularly limited thereto. As described above, these polymers are considered to have conductivity by adding an oxidizing agent or the like to form radicals or ions. In the present invention, even an insulating polymer, which is a polymer having conductivity by addition of some additive as described above, is also referred to as a “conductive polymer”. In addition, since the conductive polymer becomes a source electrode and a drain electrode, it is preferable that the conductive polymer is a material having excellent conductivity. In the channel region 25, the polymer in which the conductive polymer is converted to insulating can also serve as a protective film for the acicular semiconductor 26. Therefore, the polymer material has oxygen resistance (oxidation resistance) and moisture resistance (moisture resistance). It is preferable that the material is excellent.

  The acicular semiconductor material can be formed of a material that exhibits semiconductor characteristics in a bulk state. For example, it can be formed of a semiconductor such as silicon or germanium. These semiconductors may be doped with impurities (dopants), for example, silicon doped with phosphorus, germanium doped with boron, or the like may be used. Doping may be performed by adding a dopant to a raw material for forming the needle-shaped semiconductor, or may be performed by ion-implanting the dopant into the formed needle-shaped semiconductor. Also, semiconductor type CNTs may be used for needle-shaped semiconductors. The CNT may be either single-wall CNT or multi-wall CNT.

  The shape of the acicular semiconductor changes depending on the manufacturing method and manufacturing conditions. The average diameter of the acicular semiconductor is not particularly limited, but is preferably about 0.5 nm to 100 nm, and particularly preferably about 0.7 nm to 30 nm. The average length of the acicular semiconductor is not particularly limited, but is preferably longer than the channel length. The channel length may be determined according to the size of the target transistor. However, especially in the case of downsizing, the lower limit of the processing capability of a mask such as a photoresist is about several μm. For example, the length of the semiconductor is preferably 5 to 100 μm.

  In FIG. 2, the length of the needle-like semiconductor 26 that exists between the source electrode 23, the channel region 25, and the drain electrode 24 (that is, a single continuous needle-like semiconductor 26 is used as the source electrode 23. Although an example using a needle-like semiconductor 26 having a length extending between the channel region 25 and the drain electrode 24 is illustrated, it is not a continuous needle-like semiconductor, and the gap between these electrodes is more A structure in which a plurality of needle-like semiconductors having a short length are connected in series to connect the source electrode 23, the channel region 25, and the drain electrode 24 can also be used. A field effect transistor with higher mobility is obtained by using the needle-like semiconductor 26 having a length extending between the source electrode 23, the channel region 25, and the drain electrode 24 in one continuous needle-like semiconductor 26. Can be preferable. The same applies to the field effect transistor described with reference to FIG.

  In addition, it is preferable to align the needle-shaped semiconductor so as to be as parallel as possible in the direction connecting the source electrode 23 and the drain electrode 24. To align the needle-shaped semiconductor in this way, the type of needle-shaped semiconductor material used, etc. However, for example, a conductive polymer and a needle are formed on the gate insulating film that has been rubbed so that the needle-like semiconductor is oriented substantially parallel to the direction connecting the source electrode and the drain electrode. A solid semiconductor mixed solution may be applied. Alternatively, the mixed solution may be applied by immersing the substrate in a conductive polymer and acicular semiconductor mixed solution and pulling up the substrate substantially parallel to the direction connecting the source electrode and the drain electrode. Alternatively, an alignment film may be formed over the gate insulating film, and a conductive polymer and a needle-shaped semiconductor mixed solution may be applied thereon. Alternatively, a conductive polymer and a needle-shaped semiconductor mixed solution may be applied to a substrate in which an electric field or a magnetic field is applied to the source electrode and the drain electrode. In the case of forming the alignment film, the material is not particularly limited, but polyimide and the like are exemplified as a suitable example. The alignment film is not particularly limited by, for example, letterpress printing or spin coating, but is preferably formed to a thickness of about 40 to 50 nm. For materials that require baking such as polyimide, I do. The conductive polymer and needle-shaped semiconductor mixed solution applied on the substrate as described above are appropriately heated and dried and solidified.

  Such a structure in which needle-like semiconductors are oriented is preferable because a channel region with higher mobility can be formed. Thus, of the channel region formed between the conductive polymer and the needle-shaped semiconductor and connecting between the source electrode and the drain electrode, the portion of the conductive polymer to be the channel region 25 is determined according to the type of the conductive polymer as described above. The field effect transistor of the present invention can be formed by converting it into an insulating polymer by an appropriate method.

(Embodiment 2)
FIG. 3 is an example of a cross-sectional view of a field effect transistor using a needle-like semiconductor according to this embodiment. In the field effect transistor shown in FIG. 3, a source electrode 33 and a drain electrode 34 that are spaced apart from each other are formed on a substrate 30, and a channel region 35 that is coupled to both is formed between them. A gate insulating film 32 is formed thereon, and a gate electrode 31 is formed on the gate insulating film 32. At this time, the acicular semiconductor 36 is included in the source electrode 33, the drain electrode 34, and the channel region 35.

  For the substrate 30, the gate electrode 31, and the gate insulating film 32, the material and the formation method described in Embodiment 1 can be similarly used.

  The source electrode 33, the drain electrode 34, and the channel region 35 can be manufactured using an insulating polymer and a needle-shaped semiconductor composite material as a starting raw material (however, a conductive polymer is used as a starting raw material instead of an insulating polymer). Example 2 described below shows an example in which a conductive polymer is used as a starting material in the structure of Embodiment 2). First, an insulating polymer and a needle-shaped semiconductor composite layer are formed on the substrate 30 in portions to be the channel region 35, the source electrode 33, and the drain electrode 34. The insulating polymer and the acicular semiconductor composite layer can be formed by using a mixed liquid of the insulating polymer and the acicular semiconductor by using an inkjet method, a dip coating method, a spin coating method, or the like. It is not limited to. For adjusting the mixed liquid of the insulating polymer and the needle-shaped semiconductor, for example, an organic solvent that dissolves the insulating polymer but does not dissolve the needle-shaped semiconductor is used as the solvent. Examples of such organic solvents include organic solvents such as chloroform and DMF, although they cannot be generally specified because they vary depending on the insulating polymer and the acicular semiconductor used. Next, the source electrode 33, the drain electrode 34, and the channel region 35 can be formed by converting the insulating properties of the polymer in the source electrode 33 and the drain electrode 34 to conductivity. As a method for converting the conductivity of a polymer, a method of changing the doping amount of an additive for making it conductive, a method of changing the phase from amorphous to crystalline by applying heat, a method of changing the orientation direction of molecules and crystals Are exemplified, but not limited to these.

  The insulating polymer material is an organic material exhibiting insulating properties, and known organic molecules can be used. For example, polypyrrole, polyphenylene, polythiophene, polyphenylene vinylene, polyaniline and the like are preferably exemplified, but not limited thereto. Further, since the insulating polymer can also be a protective film for the acicular semiconductor 36 in the channel region 35, the polymer material may be a material excellent in oxygen resistance (oxidation resistance) and moisture resistance (moisture resistance). preferable.

  As the acicular semiconductor material, the materials and formation methods described in Embodiment Mode 1 can be similarly used. Further, the method described in Embodiment Mode 1 can be similarly used as the method for aligning the needle-shaped semiconductor.

  In addition, as long as the effect of this invention is acquired, there is no limitation in particular in the structure of a field effect transistor. In addition, the material and the formation method of each part described in Embodiments 1 and 2 are examples, and the present invention is not limited to this.

(Embodiment 3)
In Embodiment 3, an active matrix display, a wireless ID tag, and a portable device will be described as electronic devices including the field-effect transistor of the present invention described in Embodiment 2.

  As an example of an active matrix display, a display using an organic EL (electroluminescence) display unit will be described. FIG. 4 is a partially exploded perspective view schematically showing the configuration of the display. The display shown in FIG. 4 includes a drive circuit 50 arranged in an array on a plastic substrate 40. The drive circuit 50 includes the field effect transistor of the present invention, and is connected to the pixel electrode. On the drive circuit 50, the organic EL layer 41, the transparent electrode 42, and the protective film 43 are disposed. The organic EL layer 41 has a structure in which a plurality of layers such as an electron transport layer, a light emitting layer, and a hole transport layer are stacked. The source electrode line 44 and the gate electrode line 45 connected to the electrode of each transistor are each connected to a control circuit.

  An enlarged perspective view of an example of the drive circuit 50 and its periphery is shown in FIG. The structure of the transistor shown in FIG. 5 is basically the same as the structure of the field effect transistor shown in FIG. In the transistor illustrated in FIG. 5, a channel region 55, a source electrode 53, a drain electrode 54, a gate insulating layer 52, and a gate electrode 51 are stacked on a substrate. The drain electrode 54 is electrically connected to the pixel electrode 56 of the organic EL through the conductive line 58. The source electrode 53 is electrically connected to the source electrode line 44 through a conductive line that is formed so as to be included in a part of the source electrode line 44. An insulating layer 57 is formed at a portion where the gate electrode line 45 connected to the gate electrode 51 and the source electrode line 44 connected to the source electrode 52 intersect. The channel region 35 described above is applied to the channel region 55.

  The field effect transistor of the present invention having high mobility and small characteristic variation can be easily and stably formed on a member constituting an active matrix display, and the field effect transistor described in Embodiment Mode 2 is used. By configuring an active matrix display, an inexpensive display with high characteristics can be obtained. Further, by using the field effect transistor of the present invention, the field effect transistor can be reduced in size, and the field effect transistor can be easily formed on a flexible material such as plastic, so that flexibility and impact resistance are improved. A sheet-like display can be realized. Further, by improving the mobility of the field effect transistor, an active matrix display having a high display speed (reaction speed) can be obtained.

  In this embodiment, the case where an organic EL is used for the display portion has been described. However, the present invention is not limited to this. The present invention can also be applied to other active matrix type displays including a circuit including a field effect transistor, for example, a liquid crystal display, an electrophoretic display, a powder fluid display, and the like, thereby obtaining the same effect.

  Further, the structure of the driver circuit portion for driving the pixels is not limited to the structure shown in this embodiment mode. For example, a configuration in which a current-driving field-effect transistor and a switching field-effect transistor for controlling the current-driving field-effect transistor for driving one pixel may be combined. Further, a configuration in which a plurality of field effect transistors are combined may be employed. Further, a transistor having another structure of the present invention may be used in place of the transistor shown in FIG. 5, and in that case, the same effect can be obtained.

  Next, a case where the field effect transistor of the present invention is applied to a wireless ID tag will be described. FIG. 6 schematically shows a perspective view of an example of a wireless ID tag using the field effect transistor of the present invention.

  As shown in FIG. 6, the wireless ID tag 60 uses a film-like plastic substrate 61 as a substrate. An antenna unit 62 and a memory IC unit 63 are provided on the substrate 61. Here, the memory IC unit 63 is configured using the field effect transistor of the present invention described in the first embodiment. Since the wireless ID tag 60 has flexibility, by providing an adhesive function or an adhesive function, for example, by providing an appropriate adhesive layer or adhesive layer on the back surface of the substrate, the wireless ID tag 60 can be used for a confectionery bag or a drink can. It is possible to affix to such a non-flat thing. A protective film is provided on the surface of the wireless ID tag 60 as necessary. Although it does not specifically limit as a protective film, For example, a suitable plastic coating, the lamination of a plastic film, etc. are used.

  In this manner, by using the field effect transistor of the present invention, it is possible to attach to articles of various materials, and wireless ID tags having various shapes can be obtained. Further, by using the field effect transistor of the present invention having high mobility, a wireless ID tag having a high reaction speed (processing speed) and a high communication frequency can be obtained. Therefore, a wireless ID tag useful for various types of management such as quality control, inventory and delivery management, and manufacturing process management can be obtained.

  Note that the wireless ID tag of the present invention is not limited to the wireless ID tag shown in FIG. Therefore, there is no limitation on the arrangement and configuration of the antenna unit and the memory IC unit. For example, an ethics circuit may be incorporated in a wireless ID tag.

  In this embodiment, the antenna portion 62 and the memory IC portion 63 are formed on the plastic substrate 61. However, the present invention is not limited to this embodiment. For example, the antenna unit 62 and the memory IC unit 63 may be formed directly on the target object using a method such as ink jet printing. Even in such a case, by forming the field effect transistor of the present invention, a wireless ID tag including a transistor with improved mobility and characteristic variation can be manufactured at low cost.

  Next, a portable device including an integrated circuit including the field effect transistor of the present invention will be described. Various elements using characteristics of semiconductors such as arithmetic elements, memory elements, and switching elements are used in integrated circuits of portable devices. By using the field effect transistor of the present invention for at least a part of these elements, the field effect transistor can be miniaturized, and a considerable part can be made of an organic material such as plastic. It is also possible to manufacture portable devices having the advantages of organic materials that are excellent in impact resistance, environmental resistance when discarded, light weight, and low cost.

  As examples of the portable electronic device of the present invention, three portable devices are shown in FIGS. 7 to 9 (all are schematic perspective views). A portable television 70 shown in FIG. 7 includes a display device 71, a receiving device 72, a side switch (such as a power switch) 73, a front switch (such as a volume or screen switch) 74, an audio output unit 75, an input An output device 76 and a recording medium insertion unit 77 are provided. The integrated circuit including the field effect transistor of the present invention is used as a circuit including elements such as an arithmetic element, a storage element, and a switching element that constitute the portable television 70.

  A communication terminal device 80 such as a mobile phone shown in FIG. 8 includes a display device 81, a transmission / reception device 82, an audio output unit 83, a camera unit 84, a folding movable unit 85, an operation switch 86, and an audio input unit 87. The integrated circuit including the field effect transistor of the present invention is used as a circuit including elements such as an arithmetic element, a storage element, and a switching element constituting the communication terminal 80.

  A portable medical device 90 illustrated in FIG. 9 includes a display device 91, an operation switch 92, a medical treatment unit 93, and a percutaneous contact unit 94. The portable medical device 90 is carried around, for example, wrapped around an arm. The medical treatment unit 93 is a part that processes the biological information obtained from the transcutaneous contact unit 94 and performs medical treatment such as drug administration through the transcutaneous contact unit 94 accordingly. Specifically, for example, in the case of a diabetic patient, the component in blood is evaluated by the transcutaneous contact unit 94, and an appropriate and appropriate amount of drug can be administered from the medical treatment unit 93 to treat the result. Medical equipment. The integrated circuit including the field effect transistor of the present invention is used as a circuit including elements such as an arithmetic element, a memory element, and a switching element that constitute the portable medical device 90. A dotted line 95 indicates a part of the body such as an upper limb or a lower limb.

  In addition, although the example of the structure of the electronic device to which the field effect transistor of the present invention is applied has been described, the present invention is not limited to these structures. Further, electronic devices to which the field effect transistor of the present invention can be applied are not limited to the exemplified devices. The field effect transistor of the present invention can be miniaturized, can be formed on a light and flexible plastic substrate, and uses an inexpensive manufacturing process as compared with a technique using a conventional silicon semiconductor. It can be used as a PDA terminal (personal digital assistant terminal), wearable AV (audiovisual) device, portable computer, wristwatch type communication device, etc., mechanical flexibility, shock resistance, environmental resistance when throwing away, Applicable to equipment that requires characteristics such as light weight and low cost

  In this example, a field effect transistor was manufactured using the structure shown in FIG.

  FIG. 2 shows a field effect transistor structure in which a gate electrode 21 is formed on a substrate 20, a gate insulator 22 is formed thereon, and a source electrode 23, a drain electrode 24, and a channel region 25 are formed thereon.

  Glass substrate as substrate 20, ITO (indium tin oxide) as gate electrode 21, polyvinylphenol (PVP) as gate insulator 22, insulating as channel region 25 containing source electrode 23, drain electrode 24, and acicular semiconductor 26 A field effect transistor was manufactured using a mixed solution of polythiophene, which is a conductive polymer, and CNT, which is a needle-like semiconductor 26.

  First, a cleaned glass substrate 20 with an ITO film (thickness: 700 μm) is prepared, and a PVP gate insulator 22 is formed on the substrate 20 by spin coating (the solvent used is PGMEA [propylene glycol monomethyl ether acetate]). (Thickness: 0.3 μm) was formed. Next, a polythiophene solution in which CNT (length: 10 μm, thickness: 0.7 nm) is mixed by 1 wt% (relative to the total weight including the solvent) [solvent toluene, polythiophene content 10 wt% (total including the solvent) Was applied on the gate insulating film 22 by a spin coating method. Then, it heated to 80 degreeC on the hotplate and dried and solidified. The orientation of CNTs was oriented from the center of the circle to the outside by applying a solution containing CNTs by spin coating as described above. Finally, on the polythiophene and CNT mixed layer (thickness 0.3 μm), a mask in which the pattern of the source electrode and the drain electrode is opened at a position corresponding to the portion to be the source electrode 23 and the drain electrode 24 is applied. The source electrode 23 and the drain electrode 24 were formed in the polythiophene and CNT mixed layer by doping 0.1 mol% of iodine from the opening. At this time, the channel length of the channel region 25 was 5 μm.

The electric characteristics of the field effect transistor were evaluated by current-voltage curve measurement using a semiconductor parameter analyzer (“HP4155A” manufactured by Agilent Technologies). The measurement was performed in a nitrogen gas atmosphere. As a result, a transistor having a high mobility of 100 cm ² / Vs was stably obtained.

  In this example, a field effect transistor was manufactured using the structure shown in FIG.

  FIG. 3 shows a field effect transistor structure in which a source electrode 33, a drain electrode 34, and a channel region 35 are formed on a substrate 30, and a gate insulator 32 and finally a gate electrode 31 are formed thereon.

  Polyaniline doped with sulfonic acid as a conductive polymer as a channel region 35 containing a plastic substrate as the substrate 30, gold as the gate electrode 31, polyimide as the gate insulator 32, source electrode 33, drain electrode 34 and needle-like semiconductor 36 A field effect transistor was manufactured using a mixed solution of ZnO nanowires that are needle-like semiconductors 36.

  First, a plastic substrate 30 was prepared (here, a 70 μm thick polyester film substrate was used), and the surface of the substrate 30 was rubbed. Next, a polyaniline solution in which 3% by weight (based on the total weight including the solvent) of ZnO nanowires (length: 10 μm, thickness: 50 nm) is mixed on the substrate 30 subjected to rubbing treatment [containing solvent toluene and polyaniline] 5 wt% and 1 wt% of sulfonic acid dope (based on the total weight including the solvent) were applied on the substrate 30 using a spin coating method (thickness: 0.3 μm) on the hot plate And dried at 80 ° C. At this time, the polyaniline solution mixed with ZnO nanowires was mixed with 3% by weight of hydroxycyclohexyl phenyl ketone as a photochemical radical initiator (both based on the total weight including the solvent). Next, a mask in which an opening is formed at a position corresponding to the portion to be the channel region 35 in the ZnO nanowire and polyaniline mixed layer is applied, and only the channel region 35 is irradiated with ultraviolet light to insulate the conductive polyaniline. Converted. At this time, the channel length of the channel region 35 was set to 5 μm. In addition, the ZnO nanowire and the polyaniline mixed layer that have not been irradiated with the ultraviolet light are kept conductive and become the source electrode 33 and the drain electrode 34. Next, a polyimide solution (concentration 60% by weight) is applied onto the source electrode 33, the drain electrode 34 and the channel region 35 by using a spin coating method (solvent DMF), and baked at 180 ° C. to obtain a polyimide gate insulating film. (Thickness: 0.5 μm) was formed. Finally, gold was deposited as a gate electrode 31 on the polyimide gate insulating film 32 to a thickness of 0.1 μm.

The electric characteristics of the field effect transistor were evaluated by current-voltage curve measurement using a semiconductor parameter analyzer (“HP4155A” manufactured by Agilent Technologies) in the same manner as in Example 1. The measurement was performed in a nitrogen gas atmosphere. As a result, a transistor having a high mobility of 20 cm ² / Vs was stably obtained.

  The field effect transistor according to the present invention has an effect of high mobility and less characteristic variation as a field effect transistor using a needle-shaped semiconductor, such as an active matrix display that uses a field effect transistor to drive a pixel. It is useful in applications to various electronic devices.

Sectional view of a conventional field effect transistor Sectional drawing of the field effect transistor which concerns on one embodiment of this invention Sectional drawing of the field effect transistor which concerns on another one Embodiment of this invention The partially exploded perspective view which shows typically an example of the active matrix type display of this invention The perspective view which shows typically the drive circuit used for the active matrix type display of FIG. 4, and its periphery structure. Schematic perspective view showing a configuration of an example of a wireless ID tag of the present invention The typical perspective view which shows the structure of an example of the portable television of this invention The typical perspective view which shows the structure of an example of the communication terminal device of this invention The typical perspective view which shows the structure of an example of the portable medical device of this invention

Explanation of symbols

10, 20, 30, 40, 61 ...
11, 21, 31, 51 ... ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Gate electrode
12, 22, 32, 52 ... Gate insulating film
13, 23, 33, 53 .................. Source electrode
14, 24, 34, 54 ... Drain electrode
25, 35, 55 ... channel area
15, 26, 36 ... needle semiconductor
41 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Organic EL layer
42 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Transparent electrode
43 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Protective film
44 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Source electrode wire
45 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Gate electrode wire
50 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Drive circuit
56 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Pixel electrode
57 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Insulating film
58 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Conductive wire
60 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Wireless ID tag
62 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Antenna
63 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Memory IC
70 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Mobile TV
71, 81, 91 ... display device
72 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Receiver
73 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Side switch
74 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Front switch
75, 83 ...
76 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ I / O device
77 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Recording media insertion part
80 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Telecom terminal equipment
82 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Transceiver
84 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Camera
85 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Folding movable part
86, 92 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Operation switch
87 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Voice input section
90 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Medical portable device
93 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Medical treatment department
94 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Dermal contact
95 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Part of the body

Claims (9)

  A field effect transistor including a source electrode, a drain electrode, a gate electrode, and a needle-shaped semiconductor, wherein the needle-shaped semiconductor is covered with a conductive polymer in the source electrode and the drain electrode, and the source electrode and the drain electrode A field effect transistor, characterized in that the acicular semiconductor is covered with an insulating polymer in a channel portion connecting between them.   The field effect transistor according to claim 1, wherein a length of the acicular semiconductor is longer than the channel length.   The field effect transistor according to claim 1, wherein the acicular semiconductor is oriented in a direction connecting the source electrode and the drain electrode.   An electronic apparatus including at least one semiconductor element, wherein at least one of the semiconductor elements is the field effect transistor according to claim 1.   The electronic device according to claim 4, wherein the electronic device is an active matrix display.   The electronic device according to claim 4, wherein the electronic device is a wireless ID tag.   The electronic device according to claim 4, wherein the electronic device is a portable device.   A method of manufacturing a field effect transistor comprising a source electrode, a drain electrode, a gate electrode, and a source semiconductor, a drain electrode, and a needle-like semiconductor in a channel portion connecting between the source electrode, the drain electrode, and the source electrode, the drain electrode, and A part for forming a channel portion is formed of an insulating polymer and a needle-shaped semiconductor mixed layer, and then a part of the insulating polymer and the needle-shaped semiconductor mixed layer of the insulating polymer is converted into a conductive polymer, thereby the source. A method of manufacturing a field effect transistor, comprising forming an electrode and a drain electrode. A method of manufacturing a field effect transistor comprising a source electrode, a drain electrode, a gate electrode, and a source semiconductor, a drain electrode, and a needle-like semiconductor in a channel portion connecting between the source electrode, the drain electrode, and the source electrode, the drain electrode, and A portion for forming a channel portion is formed by a conductive polymer and a needle-shaped semiconductor mixed layer, and then a part of the conductive polymer and the needle-shaped semiconductor mixed layer is converted into an insulating polymer, thereby forming a channel portion. Forming a field effect transistor.

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