JP6019330B2 - THIN FILM TRANSISTOR, METHOD FOR PRODUCING THIN FILM TRANSISTOR, DISPLAY DEVICE, AND ELECTRONIC DEVICE - Google Patents

Description

  The present disclosure relates to a thin film transistor (TFT) using an oxide semiconductor, a method for manufacturing the thin film transistor, a display device, and an electronic apparatus.

  It is known that oxides (oxide semiconductors) of zinc (Zn), indium (In), gallium (Ga), tin (Sn), or a mixture thereof exhibit excellent semiconductor characteristics. For example, a thin film transistor using an oxide semiconductor exhibits an electron mobility that is 10 times or more that of using amorphous silicon, and favorable off characteristics. Therefore, the thin film transistor using the oxide semiconductor is expected to be applied as a driving element for a large-screen, high-definition and high-frame-rate liquid crystal display device or an organic EL (Electro Luminescence) display device.

  However, an oxide semiconductor does not have sufficient heat resistance, and oxygen is desorbed by heat treatment or plasma treatment in a thin film transistor manufacturing process to form lattice defects. This lattice defect forms a shallow impurity level electrically and causes a reduction in resistance of the oxide semiconductor. Therefore, in the case where an oxide semiconductor is used for the active layer, the threshold voltage is reduced due to an increase in the defect level, and the leakage current is increased. This causes a so-called depletion type operation in which a drain current flows without applying a gate current. Furthermore, if the defect level continues to increase, the transistor operation shifts to the conductor operation. This is considered to be due to the fact that the stability changes depending on the content ratio of a thermally unstable element, particularly in the case of a multi-element oxide semiconductor. In addition to the lattice defects as described above, hydrogen has been reported as an element that forms a shallow impurity level (Non-Patent Document 1).

JP 2010-016163 A

Cetin Kilic et al., “N-type doping of oxides by hydrogen”, APPLIED PHYSICS LETTERS, July 1, 2002, Vol. 81, No. 1, p. 73-75

  As described above, in a thin film transistor using an oxide semiconductor, characteristics of the oxide semiconductor are deteriorated in a manufacturing process thereof, which easily affects electrical characteristics. For this reason, it is desired to suppress deterioration of characteristics of the oxide semiconductor and improve electrical characteristics.

  The present disclosure has been made in view of such problems, and an object of the present disclosure is to provide a thin film transistor, a manufacturing method of the thin film transistor, a display device, and an electronic device that can realize improvement in electrical characteristics.

The thin film transistor of the present disclosure is provided with a gate electrode, a source electrode, a drain electrode, and an insulating film on one side of the gate electrode, and is provided in a region not facing the source electrode and the drain electrode. An oxide semiconductor layer electrically connected to the drain electrode; adjacent to the oxide semiconductor layer; provided in a region facing each of the source electrode and the drain electrode; and having an electrical resistivity higher than that of the oxide semiconductor layer A low-resistance oxide layer , a wiring layer provided in the same layer as the gate electrode, and a through-hole provided so as to face the wiring layer and penetrating the insulating film are provided. The low resistance oxide layer extends to the inside of the through hole and covers the wiring layer. The source electrode or the drain electrode is provided on the through hole via the low resistance oxide layer, and the wiring layer is electrically Connected .

  In the thin film transistor of the present disclosure, an oxide semiconductor layer is provided in a region not facing the source electrode and the drain electrode, and low resistance oxidation is performed in a region facing each of the source electrode and the drain electrode and adjacent to the oxide semiconductor layer. A material layer is provided. Thus, in the manufacturing process, the oxide semiconductor layer (channel layer) can be formed after the source electrode and the drain electrode are formed. In an oxide semiconductor, oxygen is released due to damage received during electrode deposition or patterning, which causes lattice defects. However, by forming an oxide semiconductor layer after electrode formation as described above, Generation of lattice defects is suppressed, and deterioration of the oxide semiconductor layer is suppressed. In addition, by providing the low resistance oxide layer adjacent to the oxide semiconductor layer, good electrical connection between the oxide semiconductor layer and the source and drain electrodes is ensured.

A method of manufacturing a thin film transistor according to the present disclosure includes a step of forming a gate electrode, a source electrode, and a drain electrode, and a region that is provided on one side of the gate electrode via an insulating film and that is not opposed to the source electrode and the drain electrode. Forming an oxide semiconductor layer electrically connected to the source electrode and the drain electrode, forming a wiring layer in the same layer as the gate electrode, and forming an insulating film facing the wiring layer Forming a through hole that penetrates . In the step of forming the oxide semiconductor layer, a low-resistance oxide layer having a lower electrical resistivity than the oxide semiconductor layer is formed in a region adjacent to the oxide semiconductor layer and facing each of the source electrode and the drain electrode. To do. The low resistance oxide layer extends to the inside of the through hole and covers the wiring layer. The source electrode or the drain electrode is provided on the through hole via the low resistance oxide layer, and the wiring layer is electrically Connected.

  In the method of manufacturing a thin film transistor according to the present disclosure, in the step of forming the oxide semiconductor layer, the oxide semiconductor layer is formed in a region not facing the source electrode and the drain electrode, facing each of the source electrode and the drain electrode, and A low-resistance oxide layer is formed in a region adjacent to the oxide semiconductor layer. Accordingly, the oxide semiconductor layer (channel layer) can be formed after the source electrode and the drain electrode are formed. In an oxide semiconductor, oxygen is released due to damage received during electrode deposition or patterning, which causes lattice defects. However, by forming an oxide semiconductor layer after electrode formation as described above, Generation of lattice defects is suppressed, and deterioration of the oxide semiconductor layer is suppressed. In addition, since the low-resistance oxide layer is formed adjacent to the oxide semiconductor layer, good electrical connection between the oxide semiconductor layer and the source and drain electrodes is ensured.

  A display device according to the present disclosure includes the thin film transistor according to the present disclosure.

  An electronic device according to the present disclosure includes a display device including the thin film transistor according to the present disclosure.

  According to the thin film transistor of the present disclosure, an oxide semiconductor layer is provided in a region not facing the source electrode and the drain electrode, and a low resistance is provided in a region facing each of the source electrode and the drain electrode and adjacent to the oxide semiconductor layer. Since the oxide layer is provided, deterioration of the oxide semiconductor layer in the manufacturing process can be suppressed. In addition, the low-resistance oxide layer can ensure good electrical connection between the oxide semiconductor layer and the source and drain electrodes. Therefore, improvement in electrical characteristics can be realized.

  According to the method for manufacturing a thin film transistor of the present disclosure, an oxide semiconductor layer is formed in a region not facing the source electrode and the drain electrode, the region facing each of the source electrode and the drain electrode and adjacent to the oxide semiconductor layer In addition, since the low-resistance oxide layer is formed, deterioration of the oxide semiconductor layer can be suppressed. In addition, the low-resistance oxide layer ensures good electrical connection between the oxide semiconductor layer and the source and drain electrodes. Therefore, improvement in electrical characteristics can be realized.

  According to the display device of the present disclosure, since the thin film transistor of the present disclosure is provided, the electrical characteristics of the thin film transistor can be improved.

  According to the electronic device of the present disclosure, since the display device including the thin film transistor of the present disclosure is included, the electrical characteristics of the thin film transistor can be improved.

2 is a cross-sectional view of a thin film transistor according to a first embodiment of the present disclosure. FIG. It is sectional drawing for demonstrating the manufacturing method of the thin-film transistor shown in FIG. FIG. 3 is a cross-sectional view illustrating a process following FIG. 2. FIG. 4 is a cross-sectional view illustrating a process following FIG. 3. FIG. 5 is a cross-sectional view illustrating a process following FIG. 4. FIG. 6 is a cross-sectional view illustrating a process following FIG. 5. It is a figure showing the electrical property before and behind a high resistance process. It is sectional drawing of the thin-film transistor which concerns on a comparative example. FIG. 9 is a cross-sectional view for explaining a method for manufacturing the thin film transistor shown in FIG. 8. It is sectional drawing for demonstrating the manufacturing method of the thin-film transistor which concerns on a modification. FIG. 11 is a cross-sectional diagram illustrating a process following the process in FIG. 10. It is sectional drawing of the thin-film transistor which concerns on 2nd Embodiment of this indication. It is sectional drawing for demonstrating the manufacturing method of the thin-film transistor shown in FIG. FIG. 14 is a cross-sectional diagram illustrating a process following the process in FIG. 13. FIG. 15 is a cross-sectional view illustrating a process following FIG. 14. It is a figure showing the whole structure containing the peripheral circuit of the display apparatus of each embodiment. It is a figure showing the pixel circuit structure of the display apparatus shown in FIG. FIG. 17 is a plan view illustrating a schematic configuration of a module including the display device illustrated in FIG. 16. 14 is a perspective view illustrating an appearance of application example 1. FIG. (A) is a perspective view showing the external appearance seen from the front side of the application example 2, (B) is a perspective view showing the external appearance seen from the back side. 12 is a perspective view illustrating an appearance of application example 3. FIG. 14 is a perspective view illustrating an appearance of application example 4. FIG. (A) is a front view of the application example 5 in an open state, (B) is a side view thereof, (C) is a front view in a closed state, (D) is a left side view, and (E) is a right side view, (F) is a top view and (G) is a bottom view. 14 is a perspective view illustrating an appearance of application example 5. FIG.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order.
1. First Embodiment (Example of thin film transistor in which an oxide semiconductor layer as a channel is formed by increasing the resistance of a part of a low-resistance oxide film after forming source / drain electrodes)
2. Modification 1 (example in which high resistance treatment is performed when forming a protective film)
3. Second Embodiment (Example of thin film transistor in which an oxide semiconductor layer is formed by crystallizing part of an oxide film)
4). Application examples (examples of display devices and electronic devices)

<First Embodiment>
[Constitution]
FIG. 1 illustrates a cross-sectional structure of a thin film transistor (thin film transistor 10A) according to the first embodiment of the present disclosure. The thin film transistor 10A is used, for example, as a drive element of an active matrix organic EL display device (described later) or a liquid crystal display device. In this thin film transistor 10A, an oxide semiconductor layer 14C is disposed on one surface side of the gate electrode 12A via a gate insulating film 13, and a pair of source / drain electrodes are electrically connected to the oxide semiconductor layer 14C. 15A and 15B are provided.

  Here, the thin film transistor 10A has a so-called bottom gate structure (inverse stagger structure), and includes a gate electrode 12A in a selective region on the substrate 11 made of glass or the like, for example. A gate insulating film 13 is formed over the entire surface of the substrate 11 so as to cover the gate electrode 12A, and an oxide semiconductor layer 14C is formed in a selective region on the gate insulating film 13 (region facing the gate electrode 12A). Is formed. Source / drain electrodes 15A and 15B are disposed above the oxide semiconductor layer 14C, and a protective film 16 is provided so as to cover the oxide semiconductor layer 14C and the source / drain electrodes 15A and 15B. It has been.

  In the thin film transistor 10A of the present embodiment, the oxide semiconductor layer 14C is formed in a region not facing the source / drain electrodes 15A, 15B (region exposed from the source / drain electrodes 15A, 15B). Low resistance oxide layers 14A and 14B are provided on the gate insulating film 13 in regions adjacent to the oxide semiconductor layer 14C and facing the source / drain electrodes 15A and 15B, respectively. That is, in this embodiment, the oxide semiconductor layer 14C and the source / drain electrodes 15A and 15B are electrically connected via the low-resistance oxide layers 14A and 14B.

  The thin film transistor 10A also includes an electrode or wiring (gate layer) provided in the same layer as the gate electrode 12A and an electrode provided in the same layer as the source / drain electrodes 15A and 15B in an arbitrary region on the substrate 11. Alternatively, a contact portion (wiring contact portion 20) for interlayer connection with the wiring (source / drain layer) is provided. In the wiring contact portion 20, the gate insulating film 13 has a contact hole H on the wiring layer 12B provided in the same layer as the gate electrode 12A. A low resistance oxide layer 14B is formed so as to cover the inside of the contact hole H, and a source / drain electrode 15B is provided on the contact hole H via the low resistance oxide layer 14B. . Hereinafter, each component will be described.

  The gate electrode 12A controls the carrier density in the oxide semiconductor layer 14C by the gate voltage (Vg) applied to the thin film transistor 10A. The gate electrode 12A is, for example, a simple substance or an alloy made of one of molybdenum (Mo), aluminum, silver (Ag), and copper (Cu), or a laminated film made of two or more of these. Examples of the aluminum alloy include an alloy of aluminum and neodymium (Nd) (AlNd alloy). The gate electrode 12A may be composed of a transparent conductive film such as ITO (indium tin oxide), AZO (aluminum doped zinc oxide), and GZO (gallium doped zinc oxide).

  The wiring layer 12B is provided in the same layer as the gate electrode 12A, for example, and is made of the same material as the gate electrode 12A. The wiring layer 12B and the gate electrode 12A are collectively patterned in the same process. The wiring layer 12B corresponds to one of wirings provided in a driving circuit in a display device described later, for example. Here, as will be described later, a plurality of transistors, capacitors, and wirings for connecting them are provided in the drive circuit, but all of these electrodes and wirings are provided in the gate layer or the source / drain layer. Arranged. In other words, in each layer of the gate layer and the source / drain layer, not only the electrodes functioning as the gate, source, and drain of the transistor but also various other wirings can be routed to realize a complicated wiring layout. Need to be connected between layers. For example, it is ideal to route wiring in a source / drain layer that can use a metal having a thicker film (that is, low resistance), but many signal lines are stretched around the source / drain layer. . Therefore, by shifting the formation region of the wiring from the source / drain layer to the gate layer, various wirings can be provided crossing each other, and a complicated wiring layout can be realized. The wiring layer 12B and the wiring contact portion 20 correspond to such a contact portion (bridge) between the source / drain layer and the gate layer.

The gate insulating film 13 is, for example, a single layer film made of one of silicon oxide (SiO _x ), silicon nitride (SiN), silicon oxynitride (SiON), or a laminated film made of two or more kinds.

  The oxide semiconductor layer 14C functions as an active layer (channel) (forms a channel when a gate voltage is applied). For example, indium (In), gallium (Ga), tin (Sn), and zinc (Zn). Etc., and an oxide of a mixture of two or more thereof. Examples of such an oxide include indium gallium zinc oxide (IGZO, InGaZnO). The oxide semiconductor layer 14C has a thickness of 20 nm to 100 nm, for example. As will be described in detail later, the oxide semiconductor layer 14C is formed by increasing the resistance of a part of the oxide film (low resistance oxide film 14) constituting the low resistance oxide layers 14A and 14B. (Corresponding to the part with high resistance).

  The low resistance oxide layers 14A and 14B are made of the same oxide as the oxide semiconductor layer 14C, and have the same thickness as the oxide semiconductor layer 14C. Although the details of the low-resistance oxide layers 14A and 14B will be described later, after a part of an oxide film (low-resistance oxide film 14) described later has a high resistance (after formation of the oxide semiconductor layer 14C). This corresponds to another region remaining without being increased in resistance. For this reason, in the low resistance oxide layers 14A and 14B, the electrical resistivity is lower than that of the oxide semiconductor layer 14C, and specifically, about 20 μΩ · m to 40Ω · m. The source / drain electrodes 15A and 15B are stacked on the low-resistance oxide layers 14A and 14B, and the surface shapes along these substrate surfaces are substantially equal. Thus, the low resistance oxide layers 14A and 14B function as electrical contact layers between the oxide semiconductor layer 14C and the source / drain electrodes 15A and 15B.

  The oxides constituting the oxide semiconductor layer 14C and the low-resistance oxide layers 14A and 14B have resistance to chemicals used when patterning the source / drain electrodes 15A and 15B. For example, when a PAN-based (phosphoric acid-acetic acid-nitric acid-based), hydrofluoric acid-based, or hydrochloric acid-based one is used as the chemical solution, the chemical solution only needs to have etching resistance. Alternatively, when the constituent materials of the oxide semiconductor layer 14C and the source / drain electrodes 15A and 15B are combinations that do not provide wet etching selectivity, the dry etching gas can be selectively selected by appropriately selecting the dry etching gas. Can be processed easily. In this embodiment, such an oxide does not have crystallinity (a property that enables crystallization), and both the oxide semiconductor layer 14C and the low-resistance oxide layers 14A and 14B are amorphous. It is quality.

  The source / drain electrodes 15A and 15B function as source electrodes or drain electrodes. Here, one is a source electrode and the other is a drain electrode. Examples of the constituent material of the source / drain electrodes 15A and 15B include the same metals or transparent conductive films as those listed in the gate electrode 12A. For example, titanium (Ti) having a thickness of 50 nm and aluminum having a thickness of 200 nm to 1 μm. It is composed of a three-layer film in which (Al) and molybdenum (Mo) with a thickness of 50 nm are stacked.

The protective film 16 is made of, for example, aluminum oxide (AlO _x ) or silicon oxide (SiO _x ), and protects the inside of the thin film transistor 10A and suppresses external air (for example, hydrogen) from entering the oxide semiconductor layer 14C. .

[Production method]
2 to 6 are cross-sectional views for explaining a method of manufacturing the thin film transistor 10A. The thin film transistor 10A can be manufactured, for example, as follows.

First, as shown in FIG. 2A, after forming the gate electrode 12A and the wiring layer 12B, the gate insulating film 13 is formed. Specifically, first, a metal film made of the above-described material is formed on the entire surface of the substrate 11 by, for example, sputtering (hereinafter simply referred to as “sputtering”) or CVD (Chemical Vapor Deposition). After the deposition, patterning is performed by etching using, for example, a photolithography method. Thereby, the gate electrode 12A and the wiring layer 12B are formed in a selective region on the substrate 11. Subsequently, a gate insulating film 13 is formed over the entire surface of the substrate 11 by, eg, CVD. At this time, as a source gas, when a silicon nitride film is formed as the gate insulating film 13, a mixed gas containing, for example, silane (SiH ₄ ), ammonia (NH ₃ ), and nitrogen is used. Alternatively, when a silicon oxide film is formed as the gate insulating film 13, for example, a mixed gas containing silane and dinitrogen monoxide (N ₂ O) is used.

  Next, as shown in FIG. 2B, a contact hole H is formed in a region on the wiring layer 12B of the formed gate insulating film 13 (region facing the wiring layer 12B) by etching using, for example, a photolithography method. Form. The contact hole H is a good electrical connection between the wiring layer 12B provided in the gate layer and the wiring provided in the source / drain layer (here, the source / drain electrodes 15A and 15B). It is desirable to process so as to obtain

  Next, as shown in FIG. 3A, the oxide film 14 (film that finally becomes the oxide semiconductor layer 14C and the low-resistance oxide layers 14A and 14B in a later step) is formed by, for example, sputtering. A film is formed over the entire surface of the substrate 11. At this time, the oxide film 14 is formed to cover the inside of the contact hole H. In addition, the film formation using the sputtering method enables the film formation on a large substrate and the process temperature to be lowered, and there is an advantage that the existing equipment used in the production line of silicon thin film transistors can be used. is there.

Specifically, when IGZO is used as the oxide, reactive sputtering (DC sputtering, RF sputtering, or AC sputtering) is performed using IGZO ceramic as a target. For example, in a sputtering apparatus, after evacuating the chamber to a predetermined degree of vacuum (for example, 1 × 10 ⁻⁴ Pa or less), the target and the substrate 11 are arranged, for example, argon (Ar) and oxygen (O ₂ ). The gas mixture is introduced to cause plasma discharge. As a result, an oxide film 14 made of IGZO is deposited on the gate insulating film 13.

  However, at this time, the sputtering conditions are adjusted so that the oxide film 14 to be formed exhibits a low electrical resistivity. Specifically, by adjusting at least one of the sputtering output (power), oxygen concentration, water vapor concentration, and sputtering back pressure, the composition ratio and crystallinity of the metal element in the film forming material are changed, and the electric power is changed. The resistivity (carrier density) can be controlled. In particular, among the above conditions, low resistance can be easily achieved by setting the oxygen concentration low. Since part of the oxide film 14 finally becomes the low-resistance oxide layers 14A and 14B, the electrical resistivity immediately after the formation of the oxide film 14 is that of the low-resistance oxide layers 14A and 14B. The electrical resistivity is obtained (the electrical resistivity of the oxide film 14 and the low resistance oxide layers 14A and 14B is equal).

  Next, as shown in FIG. 3B, a metal layer 15 (source / drain electrodes 15A and 15B) is formed. Specifically, the metal layer 15 (source / drain electrodes 15A, 15B) is deposited on the oxide film 14 by depositing the above-described electrode materials (eg, titanium, aluminum, molybdenum) in this order, for example, by sputtering. Form a film.

  The metal layer 15 is formed in succession to the oxide film 14, that is, before the oxide film 14 is patterned, the metal layer 15 to be the source / drain electrodes 15 A and 15 B is formed. Form a film.

  Subsequently, as shown in FIG. 4, the metal layer 15 is patterned by, for example, wet etching or dry etching using a photolithography method to form source / drain electrodes 15A and 15B. At this time, the etching is performed under the condition that the etching selectivity with the lower oxide film 14 can be obtained. For example, etching is performed using a chemical solution that is resistant to the oxide film 14 such as PAN, hydrofluoric acid, or hydrochloric acid. In this way, only the source / drain electrodes 15A and 15B are selectively patterned on the oxide film. At this time, a part of the source / drain electrode 15B is left in the region on the contact hole H, so that the source / drain electrode 15B is connected to the wiring layer via the oxide film 14 (low resistance oxide layer 14B). 12B is electrically connected.

  Next, as shown in FIG. 5, the oxide film 14 is patterned into, for example, an island shape by etching using, for example, a photolithography method. As a result, the oxide film 14 can be left only in the source / drain electrodes 15A and 15B and the region between the source / drain electrodes 15A and 15B, and conduction with other regions can be prevented. However, the oxide film 14 may not be patterned and may be formed on the entire surface of the substrate 11 in the case where there is no particular problem in the state where the high resistance treatment is performed later. Alternatively, the oxide film 14 may be patterned together with the protective film 16 in the subsequent step of forming the protective film 16.

  Thereafter, as shown in FIG. 6, the selective region of the oxide film 14, specifically, the region exposed from the source / drain electrodes 15A, 15B between the source / drain electrodes 15A, 15B is increased. Apply resistance treatment. For example, the resistance can be increased by performing heat treatment or plasma treatment in an oxidizing atmosphere. At this time, the previously formed source / drain electrodes 15A and 15B are used as a mask, and the selective region is oxidized to increase the resistance, and the increased resistance portion becomes the oxide semiconductor layer 14C. On the other hand, the region of the oxide film 14 facing the source / drain electrodes 15A and 15B is not exposed to an oxygen atmosphere, so that the resistance is not increased and the electrical resistivity of the oxide film 14 is maintained. Further, the portion formed extending in the contact hole H is also masked by the source / drain electrodes 15A and 15B, so that the low resistance is maintained. These portions where the resistance is not increased (portions where the low resistance is maintained) become the low resistance oxide layers 14A and 14B. In this manner, the oxide semiconductor layer 14C can be formed by increasing the resistance of the selective region of the oxide film 14 after the formation of the source / drain electrodes 15A and 15B. At the same time, the low-resistance oxide layers 14A and 14B serving as contact layers between the oxide semiconductor layer 14C and the source / drain electrodes 15A and 15B can be formed.

  Finally, the protective film 16 is formed. Specifically, an oxide film made of the above-described material is formed over the entire surface of the substrate 11 by, for example, sputtering or CVD. For example, when aluminum oxide is used, sputtering is used, for example, aluminum or aluminum oxide is used as a target, and plasma discharge is performed by a mixed gas of argon and oxygen. Alternatively, when silicon oxide is used, film formation is performed by a CVD method in a gas atmosphere containing, for example, silane and dinitrogen monoxide. Thereafter, the protective film 16 is patterned into a desired shape by etching using, for example, a photolithography method. Thus, the thin film transistor 10A shown in FIG. 1 is completed.

[Action, effect]
In the present embodiment, in the manufacturing process of the thin film transistor 10A, the oxide semiconductor layer 14C is formed in a region not facing the source / drain electrodes 15A, 15B, while facing each of the source / drain electrodes 15A, 15B; Low-resistance oxide layers 14A and 14B are formed in a region adjacent to the oxide semiconductor layer 14C. Accordingly, the oxide semiconductor layer 14C can be formed after the source / drain electrodes 15A and 15B are formed. Here, in the oxide semiconductor, oxygen is generally released due to damage received during film formation or patterning of the electrode, thereby generating a lattice defect. However, the oxide semiconductor layer 14C is formed after the electrode is formed as in this embodiment. By being formed, generation of such lattice defects is suppressed, and deterioration of the oxide semiconductor layer is suppressed. Further, the low resistance oxide layers 14A and 14B are formed adjacent to the oxide semiconductor layer 14C, thereby ensuring good electrical connection between the oxide semiconductor layer 14C and the source / drain electrodes 15A and 15B. .

  FIG. 7 shows an example of electrical characteristics of the thin film transistor 10A. The solid line in the figure indicates the IV characteristics (relationship between the drain current Ids and the gate voltage Vgs) of the thin film transistor (having the oxide semiconductor layer 14C) subjected to the high resistance process, and the broken line in the figure indicates the high resistance process. 4 shows the IV characteristics of a thin film transistor manufactured without using the oxide film 14 as a channel. As the oxide semiconductor layer 14C, an IGZO film with a thickness of 40 nm was formed with an oxygen partial pressure during sputtering deposition of 0%, and after the patterning, heat treatment (300 ° C., 2 hours) was performed in an oxygen atmosphere. It was. Thus, it can be seen that by performing the high resistance treatment, the drain current particularly during the off operation is suppressed, and the transistor operation is exhibited.

  In the present embodiment, after the oxide film 14 to be the oxide semiconductor layer 14C and the low resistance oxide layers 14A and 14B and the metal layer 15 to be the source / drain electrodes 15A and 15B are continuously formed, The metal layer 15 is patterned to form source / drain electrodes 15A and 15B. Thereafter, the oxide semiconductor layer 14C and the low resistance oxide layers 14A and 14B as described above can be formed by performing a resistance increasing process using the source / drain electrodes 15A and 15B as a mask.

  Here, a thin film transistor (thin film transistor 100) according to a comparative example of the present embodiment will be described. FIG. 8 illustrates a cross-sectional structure of the thin film transistor 100, and FIG. 9 illustrates a manufacturing method thereof. In the thin film transistor 100 as well, in this embodiment, a gate insulating film 103 is formed on the substrate 11 so as to cover the gate electrode 102A and the wiring layer 102B, and this gate insulating film 103 is opposed to the wiring layer 102B. Thus, a contact hole H is provided. However, in the comparative example, the oxide semiconductor layer 104 is patterned only in a selective region on the gate insulating film 103 (region facing the gate electrode 102A), and a part of the oxide semiconductor layer 104 is formed. Source / drain electrodes 105A and 105B are provided so as to overlap each other. In the contact hole H, only the source / drain electrode 105B is buried, thereby ensuring electrical connection between the wiring layer 102B and the source / drain electrode 105B.

  In the manufacturing process of the thin film transistor 100 of such a comparative example, after the gate insulating film 103 is formed, the oxide semiconductor layer 104 is formed as illustrated in FIG. At this time, an oxide semiconductor film is first formed over the entire surface of the substrate 10 and then subjected to a patterning process by etching using a photolithography method. Thereafter, as shown in FIG. 8B, the source / drain electrodes 105A and 105B are formed. In this case, the film forming process and the patterning process are sequentially performed. Accordingly, in the manufacturing process as in the comparative example, a film forming process by sputtering of the oxide semiconductor layer 104 and the source / drain electrodes 105A and 105B is required, and the cost is likely to increase.

  In the present embodiment, as described above, the oxide film 14 is formed in advance in a low resistance state, and after the source / drain electrodes 15A and 15B are formed, the source / drain electrodes 15A and 15B are formed. Oxidation treatment (high resistance treatment) is performed as a mask. Thus, only a necessary portion of the oxide film 14 can be selectively increased in resistance, and the oxide semiconductor layer 14C functioning as a channel can be formed. Further, in the oxide film 14, the low resistance state is maintained in a region adjacent to the oxide semiconductor layer 14 </ b> C and facing the source / drain electrodes 15 </ b> A and 15 </ b> B, and a good contact layer is obtained. Compared with a general manufacturing process, the film forming process by sputtering is reduced, and the cost can be reduced.

  In the above comparative example, if the oxide semiconductor layer 104 covers the contact hole H, it is difficult to secure electrical connection between the wiring layer 102B and the source / drain electrode 105B. It is necessary to remove the semiconductor material deposited inside. On the other hand, in this embodiment, since the oxide film 14 is formed in a low resistance state in advance, it is not necessary to remove it from the contact hole H, and patterning is not necessary.

  As described above, in the present embodiment, the oxide semiconductor layer 14C is provided in a region not facing the source / drain electrodes 15A, 15B, is opposed to each of the source / drain electrodes 15A, 15B, and is an oxide semiconductor. Since the low-resistance oxide layers 14A and 14B are provided in the region adjacent to the layer 14C, deterioration of the oxide semiconductor layer 14C in the manufacturing process can be suppressed. Further, the low resistance oxide layers 14A and 14B can ensure good electrical connection between the oxide semiconductor layer 14C and the source / drain electrodes 15A and 15B. Therefore, improvement in electrical characteristics can be realized.

  Hereinafter, modifications of the first embodiment and other embodiments will be described. In addition, the same code | symbol is attached | subjected about the component similar to the said 1st Embodiment, and description is abbreviate | omitted suitably.

<Modification 1>
In the first embodiment, in the manufacturing process, the resistance of the oxide film 14 is increased before the protective film 16 is formed by heat treatment or plasma treatment in an oxidizing atmosphere. The high resistance treatment may be performed in the process of forming the protective film 16. That is, as described above, the protective film 16 is formed by, for example, a sputtering method using oxygen gas or a CVD method using a gas containing dinitrogen monoxide. Therefore, as shown in FIG. 10, the oxide film 14 can be selectively oxidized by exposing the oxide film 14 to the film formation atmosphere (oxygen atmosphere) of the protective film 16. That is, the formation process of the protective film 16 can also serve as the oxidation process (high resistance process) in the first embodiment. As a result, as shown in FIG. 11, the oxide semiconductor layer 14C and the low-resistance oxide layers 14A and 14B can be formed simultaneously with the formation of the protective film 16, respectively.

<Second Embodiment>
FIG. 12 illustrates a cross-sectional structure of a thin film transistor (thin film transistor 10B) according to the second embodiment of the present disclosure. The thin film transistor 10B, like the thin film transistor 10A of the first embodiment, has a bottom gate structure, and an oxide semiconductor layer 17C is formed on the gate insulating film 13 in a region not facing the source / drain electrodes 15A and 15B. It is formed. Low resistance oxide layers 17A and 17B are formed in regions adjacent to the oxide semiconductor layer 17C and facing the source / drain electrodes 15A and 15B.

  The oxide semiconductor layer 17C and the low-resistance oxide layers 17A and 17B are made of an oxide containing the same element (such as indium) as the oxide semiconductor layer 14C of the first embodiment. The low resistance oxide layers 17A and 17B have a lower electrical resistivity than the oxide semiconductor layer 17C, and the low resistance oxide layer 17B is formed so as to cover the contact hole H.

  However, in this embodiment, as the oxide included in the oxide semiconductor layer 17C and the low-resistance oxide layers 17A and 17B, an oxide having crystallinity (a property that can be crystallized) is used. In the manufacturing process, after the film is formed in an amorphous state, it is crystallized in a selective region after the source / drain electrodes 15A and 15B are formed. Accordingly, the oxide semiconductor layer 17C has a crystallized state, and the low resistance oxide layers 17A and 17B have an amorphous state. Hereinafter, the manufacturing process of the present embodiment will be described.

  Specifically, first, similarly to the first embodiment, after forming the gate electrode 12A and the wiring layer 12B on the substrate 11, the gate insulating film 13 having the contact hole H is formed. Thereafter, as shown in FIG. 13, the oxide film 17 and the metal layer 15 are continuously formed on the gate insulating film 13 by, for example, the sputtering method as described above. At this time, the sputtering conditions are adjusted so that the oxide film 17 has a low electrical resistivity and is formed in an amorphous state.

  Subsequently, as shown in FIG. 14, the metal layer 15 is patterned to form the source / drain electrodes 15A and 15B in the same manner as in the first embodiment, and then the oxide film 17 is patterned. To do.

  Thereafter, as shown in FIG. 15, the selective region of the oxide film 17, specifically, the region exposed from the source / drain electrodes 15A, 15B between the source / drain electrodes 15A, 15B is increased. Apply resistance treatment. For example, by performing heat treatment or plasma treatment in an oxidizing atmosphere, the selective region of the oxide film 17 in an amorphous state is crystallized while being exposed to an oxygen atmosphere, thereby increasing the resistance. It is possible. At this time, as in the first embodiment, the source / drain electrodes 15A and 15B previously formed serve as a mask, and the selective region has a high resistance, and the high resistance portion is an oxide semiconductor. Layer 17C is formed. On the other hand, in the region of the oxide film 17 facing the source / drain electrodes 15A and 15B, a part thereof may be crystallized, but even if it is crystallized, it is not exposed to the oxygen atmosphere. Therefore, a sufficiently low resistivity can be maintained. The portions that did not contribute to the increase in resistance become the low resistance oxide layers 17A and 17B. Thus, also in this embodiment, after the source / drain electrodes 15A and 15B are formed, the oxide semiconductor layer 17C is formed by increasing the resistance of the selective region of the oxide film 17, Low resistance oxide layers 14A and 14B as contact layers can be formed.

  Finally, the protective film 16 is formed in the same manner as in the first embodiment, thereby completing the thin film transistor 10B shown in FIG.

  As described above, the resistance can be increased by forming the oxide film 17 using a crystalline oxide and selectively crystallizing the oxide film 17. Even in such a case, the low-resistance oxide layers 17A and 17B can maintain substantially the same electrical resistivity as that of the oxide film 17, so that the same effect as that of the first embodiment can be obtained. it can.

<Application example>
[Display device]
Next, the thin film transistors (thin film transistors 10A and 10B) according to the above embodiments and modifications can be applied to display devices and electronic devices as described below, for example. FIG. 16 illustrates an overall configuration including peripheral circuits of a display device used as an organic EL display. Thus, for example, a display region 30 in which a plurality of pixels PXLC including organic EL elements are arranged in a matrix is formed on the substrate 11, and a horizontal line as a signal line driving circuit is formed around the display region 30. A selector (HSEL) 31, a write scanner (WSCN) 32 as a scanning line driving circuit, and a power scanner (DSCN) 33 as a power line driving circuit are provided.

  In the display area 30, a plurality (n integers) of signal lines DTL1 to DTLn are arranged in the column direction, and a plurality (m integers) of scanning lines WSL1 to WSLm and power supply lines DSL1 to DSLm are respectively arranged in the row direction. Has been placed. In addition, each pixel PXLC (any one of pixels corresponding to R, G, and B) is provided at the intersection of each signal line DTL and each scanning line WSL. Each signal line DTL is connected to a horizontal selector 31, and a video signal is supplied from the horizontal selector 31 to each signal line DTL. Each scanning line WSL is connected to the write scanner 32, and a scanning signal (selection pulse) is supplied from the write scanner 32 to each scanning line WSL. Each power supply line DSL is connected to the power supply scanner 33, and a power supply signal (control pulse) is supplied from the power supply scanner 33 to each power supply line DSL.

  FIG. 17 illustrates a specific circuit configuration example in the pixel PXLC. Each pixel PXLC has a pixel circuit 40 including an organic EL element 3D. The pixel circuit 40 is an active driving circuit having a sampling transistor 3A and a driving transistor 3B, a storage capacitor element 3C, and an organic EL element 3D. Among these, the transistor 3A (or transistor 3B) corresponds to the thin film transistors 10A and 10B in the above-described embodiment and the like.

  Sampling transistor 3A has its gate connected to corresponding scanning line WSL, one of its source and drain connected to corresponding signal line DTL, and the other connected to the gate of driving transistor 3B. The drive transistor 3B has a drain connected to the corresponding power supply line DSL and a source connected to the anode of the organic EL element 3D. The cathode of the organic EL element 3D is connected to the ground wiring 5H. The ground wiring 5H is wired in common to all the pixels PXLC. The storage capacitor element 3C is disposed between the source and gate of the driving transistor 3B.

  The sampling transistor 3A conducts according to the scanning signal (selection pulse) supplied from the scanning line WSL, thereby sampling the signal potential of the video signal supplied from the signal line DTL and holding it in the storage capacitor element 3C. Is. The driving transistor 3B is supplied with a current from a power supply line DSL set to a predetermined first potential (not shown), and changes the driving current to an organic EL element according to the signal potential held in the holding capacitor element 3C. Supply to 3D. The organic EL element 3D emits light with a luminance corresponding to the signal potential of the video signal by the driving current supplied from the driving transistor 3B.

  In such a circuit configuration, the sampling transistor 3A is turned on according to the scanning signal (selection pulse) supplied from the scanning line WSL, whereby the signal potential of the video signal supplied from the signal line DTL is sampled and held. It is held in the capacitive element 3C. In addition, a current is supplied from the power supply line DSL set to the first potential to the driving transistor 3B, and the driving current is changed to the organic EL element 3D (red, green and red) according to the signal potential held in the holding capacitor element 3C. To each blue organic EL element). Each organic EL element 3D emits light with a luminance corresponding to the signal potential of the video signal by the supplied drive current. Thereby, video display based on the video signal is performed on the display device.

  The display device using the thin film transistors 10A and 10B as described above can be applied to the following electronic devices, for example. Examples of the electronic device include a television device, a digital camera, a notebook personal computer, a mobile terminal device such as a mobile phone, or a video camera. In other words, the display device can be applied to electronic devices in various fields that display a video signal input from the outside or a video signal generated inside as an image or video.

(module)
The display device is incorporated into various electronic devices such as application examples 1 to 6 described later, for example, as a module shown in FIG. In this module, for example, an area 210 exposed from the sealing substrate 60 is provided on one side of the substrate 11, and the wiring of the horizontal selector 31, the light scanner 32, and the power scanner 33 is extended to the exposed area 210. A connection terminal (not shown) is formed. The external connection terminal may be provided with a flexible printed circuit (FPC) 220 for signal input / output.

(Application example 1)
FIG. 19 illustrates the appearance of a television device. This television apparatus has, for example, a video display screen unit 300 including a front panel 310 and a filter glass 320, and the video display screen unit 300 corresponds to the display device.

(Application example 2)
FIG. 20 shows the appearance of a digital camera. The digital camera includes, for example, a flash light emitting unit 410, a display unit 420, a menu switch 430, and a shutter button 440, and the display unit 420 corresponds to the display device.

(Application example 3)
FIG. 21 shows the appearance of a notebook personal computer. The notebook personal computer has, for example, a main body 510, a keyboard 520 for inputting characters and the like, and a display unit 530 for displaying an image. The display unit 530 corresponds to the display device.

(Application example 4)
FIG. 22 shows the appearance of the video camera. This video camera includes, for example, a main body 610, a subject photographing lens 620 provided on the front side surface of the main body 610, a start / stop switch 630 at the time of photographing, and a display 640. The display unit 640 corresponds to the display device.

(Application example 5)
FIG. 23 shows the appearance of a mobile phone. This mobile phone is obtained by connecting, for example, an upper housing 710 and a lower housing 720 with a connecting portion (hinge portion) 730, and includes a display 740, a sub-display 750, a picture light 760, and a camera 770. . Of these, the display 740 or the sub-display 750 corresponds to the display device.

(Application example 6)
FIG. 24 shows the appearance of the smartphone. The smartphone includes a display unit 810, a non-display unit (housing) 820, and an operation unit 830, for example. The operation unit 830 may be provided on the front surface of the non-display unit 820 as shown in (A), or may be provided on the upper surface as shown in (B).

  As described above, the present disclosure has been described with reference to the embodiment and the modification. However, the present disclosure is not limited to the embodiment and the like, and various modifications can be made. For example, in the above-described embodiments and the like, a bottom gate thin film transistor has been described as an example. However, the thin film transistor of the present disclosure may be a top gate thin film transistor.

  In the above-described embodiment and the like, the case where the wiring contact portion between the source / drain electrodes and the gate wiring layer is illustrated, but this wiring contact portion may not be provided. For example, a wiring contact portion is formed in an organic EL display device, but is often not formed in a liquid crystal display device.

  Furthermore, the thin film transistor of the present disclosure is not limited to the stacked structure described in the above embodiment, and the material, thickness, manufacturing process, and the like of each layer are not limited to those described above.

Note that the present disclosure may have the following configuration.
(1)
A gate electrode, a source electrode and a drain electrode;
An oxide provided on one side of the gate electrode via an insulating film, provided in a region not facing the source electrode and the drain electrode, and electrically connected to the source electrode and the drain electrode A semiconductor layer;
A thin film transistor comprising: a low-resistance oxide layer adjacent to the oxide semiconductor layer and provided in a region facing each of the source electrode and the drain electrode and having a lower electrical resistivity than the oxide semiconductor layer .
(2)
The oxide semiconductor layer and the low-resistance oxide layer are provided on the gate electrode via the insulating film,
The thin film transistor according to (1), wherein the source electrode and the drain electrode are provided on the low-resistance oxide layer.
(3)
The thin film transistor according to (1) or (2), wherein the oxide semiconductor layer and the low-resistance oxide layer are made of the same oxide material.
(4)
The thin film transistor according to any one of (1) to (3), wherein the low-resistance oxide layer has an amorphous state, and the oxide semiconductor layer has a crystallized state.
(5)
The thin film transistor according to any one of (1) to (4), wherein the oxide material has resistance to a chemical solution used when patterning the source electrode and the drain electrode.
(6)
The insulating film has a through hole on a wiring layer provided in the same layer as the gate electrode,
The thin film transistor according to any one of (1) to (5), wherein a part of the low resistance oxide layer is formed so as to cover an inside of the through hole.
(7)
The thin film transistor according to (6), wherein the source electrode or the drain electrode is provided on the through hole via the low-resistance oxide layer and is electrically connected to the wiring layer.
(8)
A protective film is provided so as to cover the oxide semiconductor layer, the source electrode, and the drain electrode. The thin film transistor according to any one of (1) to (7).
(9)
The thin film transistor according to (8), wherein the protective film is made of silicon oxide (SiO _x ) or aluminum oxide (AlO _x ).
(10)
Forming each of a gate electrode, a source electrode and a drain electrode;
An oxide provided on one side of the gate electrode through an insulating film, provided in a region not facing the source electrode and the drain electrode, and electrically connected to the source electrode and the drain electrode Forming a semiconductor layer,
In the step of forming the oxide semiconductor layer,
A method for manufacturing a thin film transistor, wherein a low-resistance oxide layer having an electrical resistivity lower than that of the oxide semiconductor layer is formed in a region adjacent to the oxide semiconductor layer and facing each of the source electrode and the drain electrode.
(11)
After forming the gate electrode,
An oxide film partially corresponding to the low-resistance oxide layer is formed on the gate electrode via the insulating film,
Forming the source electrode and the drain electrode on the formed oxide film;
After forming the source electrode and the drain electrode, the oxide semiconductor layer is formed by subjecting a selective region of the oxide film exposed from the source electrode and the drain electrode to high resistance. The manufacturing method of the thin-film transistor as described in said (10).
(12)
The method for manufacturing a thin film transistor according to (11), wherein a heat treatment in an oxygen atmosphere is performed as the high resistance treatment.
(13)
Forming a protective film in an oxygen atmosphere after forming the source electrode and the drain electrode,
In the process of forming the protective film, the high resistance treatment is performed by exposing the selective region of the oxide film to an oxygen atmosphere. The method for manufacturing a thin film transistor according to the above (11) or (12).
(14)
Silicon oxide (SiO _x ) or aluminum oxide (AlO _x ) is formed as the protective film. The method for manufacturing a thin film transistor according to (13) above.
(15)
Forming the oxide film in an amorphous state;
The method for manufacturing a thin film transistor according to (11), wherein a treatment for crystallizing the selective region of the oxide film is performed as the high resistance treatment.
(16)
The oxide film is a thin film transistor according to any one of (11) to (15), wherein the oxide film has resistance to a chemical solution used when patterning the source electrode and the drain electrode.
(17)
A through hole is formed on a wiring layer provided in the same layer as the gate electrode in the insulating film,
The method for manufacturing a thin film transistor according to any one of (11) to (16), wherein the oxide film is formed so as to cover an inside of the through hole.
(18)
The source electrode or the drain electrode is electrically connected to the wiring layer by forming the source electrode or the drain electrode in the through hole or on the through hole via the oxide film. (17) The manufacturing method of the thin-film transistor as described in (17).
(19)
A gate electrode, a source electrode and a drain electrode;
An oxide provided on one side of the gate electrode via an insulating film, provided in a region not facing the source electrode and the drain electrode, and electrically connected to the source electrode and the drain electrode A semiconductor layer;
A thin film transistor comprising: a low-resistance oxide layer adjacent to the oxide semiconductor layer and provided in a region facing each of the source electrode and the drain electrode and having a lower electrical resistivity than the oxide semiconductor layer A display device.
(20)
A display device having a thin film transistor;
The thin film transistor
A gate electrode, a source electrode and a drain electrode;
An oxide provided on one side of the gate electrode via an insulating film, provided in a region not facing the source electrode and the drain electrode, and electrically connected to the source electrode and the drain electrode A semiconductor layer;
An electron comprising: a low resistance oxide layer adjacent to the oxide semiconductor layer and provided in a region facing each of the source electrode and the drain electrode and having a lower electrical resistivity than the oxide semiconductor layer. machine.

  10A, 10B ... thin film transistor, 11 ... substrate, 12A ... gate electrode, 13 ... gate insulating film, 14C, 17C ... oxide semiconductor layer, 14A, 14B, 17A, 17B ... low resistance oxide layer, 15A, 15B ... source Drain electrode, 16 ... protective film, 14 ... oxide film, 15 ... metal layer, 20 ... wiring contact portion, 12B ... wiring layer, H ... contact hole.

Claims (16)

A gate electrode, a source electrode and a drain electrode;
An oxide provided on one side of the gate electrode via an insulating film, provided in a region not facing the source electrode and the drain electrode, and electrically connected to the source electrode and the drain electrode A semiconductor layer;
A low resistance oxide layer adjacent to the oxide semiconductor layer and provided in a region facing each of the source electrode and the drain electrode, and having a lower electrical resistivity than the oxide semiconductor layer ;
A wiring layer provided in the same layer as the gate electrode;
A through hole provided opposite to the wiring layer and penetrating the insulating film;
With
The low-resistance oxide layer extends to the inside of the through hole and covers the wiring layer,
The source electrode or the drain electrode is a thin film transistor provided on the through hole via the low-resistance oxide layer and electrically connected to the wiring layer . The oxide semiconductor layer and the low-resistance oxide layer are provided on the gate electrode via the insulating film,
The thin film transistor according to claim 1, wherein the source electrode and the drain electrode are provided on the low-resistance oxide layer. The thin film transistor according to claim 1, wherein the oxide semiconductor layer and the low-resistance oxide layer are made of the same oxide material. The thin film transistor according to claim 3, wherein the low-resistance oxide layer has an amorphous state, and the oxide semiconductor layer has a crystallized state. The thin film transistor according to claim 3, wherein the oxide material is resistant to a chemical solution used when patterning the source electrode and the drain electrode. The thin film transistor according to claim 2, wherein a protective film is provided to cover the oxide semiconductor layer, the source electrode, and the drain electrode. The thin film transistor according to claim 6, wherein the protective film is made of silicon oxide (SiO _x ) or aluminum oxide (AlO _x ). Forming each of a gate electrode, a source electrode and a drain electrode;
An oxide provided on one side of the gate electrode through an insulating film, provided in a region not facing the source electrode and the drain electrode, and electrically connected to the source electrode and the drain electrode Forming a semiconductor layer ;
Forming a wiring layer in the same layer as the gate electrode;
Forming a through-hole penetrating the insulating film facing the wiring layer;
Have
In the step of forming the oxide semiconductor layer, a low resistance having an electrical resistivity lower than that of the oxide semiconductor layer in a region adjacent to the oxide semiconductor layer and facing each of the source electrode and the drain electrode. Forming an oxide layer ,
The low-resistance oxide layer extends to the inside of the through hole and covers the wiring layer,
The method of manufacturing a thin film transistor, wherein the source electrode or the drain electrode is provided on the through hole via the low-resistance oxide layer and is electrically connected to the wiring layer . After forming the gate electrode,
An oxide film partially corresponding to the low-resistance oxide layer is formed on the gate electrode via the insulating film,
Forming the source electrode and the drain electrode on the formed oxide film;
After forming the source electrode and the drain electrode, the oxide semiconductor layer is formed by subjecting a selective region of the oxide film exposed from the source electrode and the drain electrode to high resistance. The manufacturing method of the thin-film transistor of Claim 8. The method for manufacturing a thin film transistor according to claim 9, wherein heat treatment in an oxygen atmosphere is performed as the high resistance treatment. Forming a protective film in an oxygen atmosphere after forming the source electrode and the drain electrode,
10. The method of manufacturing a thin film transistor according to claim 9, wherein in the formation process of the protective film, the high resistance treatment is performed by exposing the selective region of the oxide film to an oxygen atmosphere. The method for manufacturing a thin film transistor according to claim 11, wherein silicon oxide (SiO _x ) or aluminum oxide (AlO _x ) is formed as the protective film. Forming the oxide film in an amorphous state;
The method for manufacturing a thin film transistor according to claim 9, wherein a treatment for crystallizing the selective region of the oxide film is performed as the high resistance treatment. The method for manufacturing a thin film transistor according to claim 9, wherein the oxide film is resistant to a chemical solution used when patterning the source electrode and the drain electrode. A gate electrode, a source electrode and a drain electrode;
An oxide provided on one side of the gate electrode via an insulating film, provided in a region not facing the source electrode and the drain electrode, and electrically connected to the source electrode and the drain electrode A semiconductor layer;
A low resistance oxide layer adjacent to the oxide semiconductor layer and provided in a region facing each of the source electrode and the drain electrode, and having a lower electrical resistivity than the oxide semiconductor layer ;
A wiring layer provided in the same layer as the gate electrode;
A through hole provided opposite to the wiring layer and penetrating the insulating film;
With
The low-resistance oxide layer extends to the inside of the through hole and covers the wiring layer,
The display device having a thin film transistor in which the source electrode or the drain electrode is provided on the through hole via the low-resistance oxide layer and is electrically connected to the wiring layer . A display device having a thin film transistor;
The thin film transistor
A gate electrode, a source electrode and a drain electrode;
An oxide provided on one side of the gate electrode via an insulating film, provided in a region not facing the source electrode and the drain electrode, and electrically connected to the source electrode and the drain electrode A semiconductor layer;
A low resistance oxide layer adjacent to the oxide semiconductor layer and provided in a region facing each of the source electrode and the drain electrode, and having a lower electrical resistivity than the oxide semiconductor layer ;
A wiring layer provided in the same layer as the gate electrode;
A through hole provided opposite to the wiring layer and penetrating the insulating film;
With
The low-resistance oxide layer extends to the inside of the through hole and covers the wiring layer,
The electronic device in which the source electrode or the drain electrode is provided on the through hole via the low-resistance oxide layer and is electrically connected to the wiring layer .

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