CN107346789A - Oxide thin film transistor and preparation method thereof - Google Patents

Abstract

The invention discloses an oxide thin film transistor and a preparation method thereof. The oxide thin film transistor comprises: a substrate, a gate, a gate insulating layer, a semiconductor active layer, a source electrode, and a drain electrode; On the substrate, the gate insulating layer is located on the gate, the semiconductor active layer is located on the gate insulating layer, the source electrode and the drain electrode are located on the semiconductor and pass through the oxide insulating film separated. The present invention oxidizes the metal conductive thin film layer above the back channel of the semiconductor active layer by anodic oxidation, and prepares the source electrode, the drain electrode and the passivation layer at the same time, effectively avoiding the damage to the semiconductor by the source electrode and the drain electrode in the patterning process. The damage or pollution caused by the active layer reduces the interface defects between the source electrode, the drain electrode and the semiconductor active layer, greatly simplifies the preparation process, reduces the cost, and is suitable for industrial production.

Description

Oxide thin film transistor and its preparation method

technical field

The invention relates to the technical field of transistor preparation, and more specifically, the invention relates to an oxide thin film transistor and a preparation method thereof.

Background technique

Thin Film Transistor (TFT, Thin Film Transistor) is a kind of production effect transistor, which is mainly used to control and drive the sub-pixels of liquid crystal display (LCD, Liquid Crystal Display) and organic light-emitting diode (OLED, Organic Light-Emitting Diode) display. The core technology shown.

TFTs based on metal oxide semiconductor materials have high electron mobility (1-100cm ² /Vs), low preparation temperature (below 400°C, far below the melting point of glass), and low cost (only ordinary sputtering process is required. Can be completed) and good stability of continuous work, it is considered to be the most promising TFT backplane technology for the next generation, and has been extensively researched by academia and industry.

Commonly used structures of oxide thin film transistors include a back channel etch (BCE) structure and an etch stop layer (ESL) structure. BCE has a simple structure and is easy to obtain the smallest device size. It has great application potential in ultra-high-definition displays. However, since oxide semiconductors are easily etched by etching solutions, the etching solution is used in the process of patterning source and drain electrodes. The underlying oxide semiconductor layer will be etched away. Therefore, the patterning process of the source and drain electrodes is a great difficulty in the actual preparation process. The ESL structure is to deposit an insulating film on the oxide semiconductor layer before patterning the source and drain electrodes to protect the oxide channel layer. This structure can effectively avoid etching of the oxide by the etching solution when etching the source and drain electrodes. However, an additional photolithography process is added to the ESL structure, which increases the complexity of the process. Therefore, its manufacturing cost also increases accordingly, and it cannot obtain a smaller device size.

In addition, regardless of the BCE structure or the ESL structure, the conductive films used as source and drain electrodes are all deposited in a vacuum environment after the semiconductor film is exposed to the atmosphere and patterned. Therefore, the surface of the semiconductor film will inevitably introduce pollution. This will increase the defects between the source and drain electrodes and the interface of the active layer, which is not conducive to the preparation of high-performance devices.

Contents of the invention

Based on this, the present invention aims to provide an oxide thin film transistor, which has stable electrical performance, good switching performance and obvious field effect characteristics.

Another object of the present invention is to provide a method for preparing an oxide thin film transistor. The invention oxidizes the metal conductive film above the back channel of the semiconductor active layer (that is, the channel layer) through an anodic oxidation method, and prepares the source electrode, the drain electrode and the passivation layer at the same time. The method effectively avoids damage or pollution to the semiconductor active layer caused by the source electrode and the drain electrode during the patterning process, and reduces interface defects between the source electrode, the drain electrode and the semiconductor active layer. The preparation method of the oxide thin film transistor of the present invention greatly simplifies the preparation process, reduces the cost, and is suitable for industrial production.

Its technical scheme is as follows:

An oxide thin film transistor, comprising: a substrate, a gate, a gate insulating layer, a semiconductor active layer, a source electrode, and a drain electrode; the gate is located on the substrate, and the gate insulating layer is located on the gate Above, the semiconductor active layer is located on the gate insulating layer, and the source electrode and the drain electrode are located on the semiconductor active layer and separated by an oxide insulating film layer.

The source electrode and the drain electrode of the oxide thin film transistor according to the present invention are separated by an oxide insulating film layer, and the oxide insulating film layer can be used as a passivation layer to protect the semiconductor active layer from being damaged by atmospheres such as water and oxygen in the air. influences. The oxide thin film transistor has stable electrical performance, good switching performance and obvious field effect characteristics.

In one embodiment, the material of the oxide insulating film layer is Al ₂ O ₃ , Ta ₂ O ₅ , CuO or Al—Nd oxide.

In one embodiment, the material of the source electrode and the drain electrode is Al, Ta, Cu or Al-Nd.

In one embodiment, the thicknesses of the source electrode and the drain electrode are respectively 10-500 nm, preferably 20-200 nm, more preferably 30-100 nm, and most preferably 40-70 nm.

In one of the embodiments, the material of the semiconductor active layer is binary oxide and/or multi-component oxide. The binary oxides may be ZnO, In ₂ O ₃ , Ga ₂ O ₃ and SnO ₂ oxides with wider band gaps. The multi-component oxide may be a ternary oxide such as: InZnO, GaZnO, ZnSnO, NdInO, ZrInO, InSnO, InWO and InTiO. The multi-component oxide can also be a quaternary oxide such as: InGaZnO, InAlZnO, HfInZnO, ZnInZnO and LaInZnO, etc. In addition, the multi-element oxide may also be a quaternary oxide further doped with other elements.

In one embodiment, the semiconductor active layer has a thickness of 10-100 nm.

In one of the embodiments, the gate insulating layer is a metal oxide film. The material of the gate insulating layer includes but not limited to Al ₂ O ₃ , Ta ₂ O ₅ and other insulating materials.

In one embodiment, the material of the gate includes but not limited to Al, Ta, Cu, Al-Nd and the like.

The preparation method of the oxide thin film transistor comprises the following steps:

Select the substrate;

forming a gate on the substrate;

forming a gate insulating layer on the gate;

forming a semiconductor active layer on the gate insulating layer;

forming a metal conductive thin film layer on the semiconductor active layer, the metal conductive thin film layer is provided with a source electrode region, a drain electrode region and an insulating region;

Form a photoresist on the metal conductive film layer, pattern it by photolithography, expose the insulating region, and form a source electrode protection layer and a drain electrode protection layer on the source electrode region and the drain electrode region respectively layer, to obtain a protective layer device;

placing the protective layer-containing device in an electrolyte solution, and completely oxidizing the insulating region by anodic oxidation to form an oxide insulating film layer;

The substrate containing the oxide insulating thin film layer is taken out, and the source electrode protection layer and the drain electrode protection layer are removed to obtain an oxide thin film transistor.

In the process of preparing an oxide thin film transistor in the present invention, a metal conductive thin film layer is prepared on the semiconductor active layer, and the metal conductive thin film layer is provided with a source electrode region, a drain electrode region and an insulating region. The photoresist is prepared on the conductive film layer, and the insulating area in the middle of the metal conductive film layer is exposed by patterning by photolithography, and then the exposed insulating area is oxidized by anodic oxidation, that is, the semiconductor is oxidized by anodic oxidation. The metal conductive thin film layer above the back channel of the source layer, the source electrode, the drain electrode and the passivation layer are prepared at the same time. This method effectively avoids damage or pollution to the active layer caused by the source electrode and the drain electrode during the patterning process, reduces the interface defects between the source electrode, the drain electrode and the active layer, and saves additional passivation layer preparation process, greatly saving costs.

In one of the embodiments, the formation of the grid on the substrate is: preparing a grid with a thickness of 100-500 nm on the substrate by inkjet printing or magnetron sputtering deposition-wet etching patterning. pole.

In one of the embodiments, the formation of the gate on the substrate is: preparing a layer of conductive film with a thickness of 100-500 nm on the substrate by sputtering, and patterning it by a blocking mask or photolithography Prepare grid. The material of the grid is metal or metal alloy.

In one of the embodiments, the formation of the gate insulating layer on the gate is as follows: anodic oxidation, thermal oxidation, physical vapor deposition or chemical vapor deposition on the upper part of the gate with a thickness of 100- 1000nm insulating film, and patterning the gate insulating layer by masking or photolithography.

In one of the embodiments, the semiconductor active layer is formed by patterning an oxide semiconductor thin film.

In one embodiment, the formation of the semiconductor active layer on the gate insulating layer is: preparing a semiconductor active layer with a thickness of 10-100 nm by magnetron sputtering deposition-wet etching patterning method.

In one of the embodiments, the formation of the semiconductor active layer on the gate insulating layer is: preparing a thin film with a thickness of 10-100 nm by magnetron sputtering, and patterning it by means of a blocking mask semiconductor active layer.

In one of the embodiments, the formation of the metal conductive film layer on the semiconductor active layer is: preparing a layer of metal conductive film layer with a thickness of 10-500 nm on the semiconductor active layer by magnetron sputtering. film layer.

In one embodiment, the thickness of the metal conductive film layer is 20-200 nm.

In one embodiment, the thickness of the metal conductive film layer is 30-100 nm.

In one embodiment, the thickness of the metal conductive thin film layer is 40-70 nm.

In one embodiment, the anodic oxidation is as follows: the device containing the protective layer is an anode, Pt is a cathode, and a constant current of 0.1-1mA/ ^cm2 is applied to oxidize, when the voltage between the two electrodes reaches a set value of 70-150V , and then oxidized at a constant voltage until the current has no change.

In one embodiment, the electrolyte is an aqueous solution of ammonium tartrate and ethylene glycol, wherein the mass fraction of ammonium tartrate is 3.48wt%, and the volume ratio of ammonium tartrate to ethylene glycol is 1:3.

In one embodiment, the thickness of the photoresist is 500-1200nm.

The beneficial effect of the present invention is that: the metal conductive film used as the source electrode and the drain electrode in the present invention is deposited and prepared without breaking the vacuum after the deposition of the semiconductor active layer is completed. Therefore, the interface between the source electrode, the drain electrode and the active layer No pollution and few defects; the preparation of the source electrode and the drain electrode will not cause damage to the active layer, and no additional etching of the barrier layer is required, the process is simple and the production cost is low; the metal conductive film above the semiconductor active layer is oxidized into Metal oxide insulating layer film, which can be used as a passivation layer to protect the semiconductor active layer from the influence of water, oxygen and other atmospheres in the air, does not require additional preparation of a passivation layer, saves the cumbersome passivation layer preparation process, and is extremely The preparation procedure is greatly simplified, the cost is reduced, and the method is suitable for industrial production.

Description of drawings

FIG. 1 is a schematic diagram of depositing and patterning a conductive metal layer as a gate according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of depositing a first insulating film on a metal conductive layer as a gate insulating layer according to an example of the present invention.

FIG. 3 is a schematic diagram of depositing an oxide semiconductor active layer according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of depositing a metal conductive film layer according to an embodiment of the present invention.

FIG. 5 is a schematic diagram of depositing photoresist on a metal conductive film layer according to an embodiment of the present invention.

FIG. 6 is a schematic diagram of a patterned photoresist according to an embodiment of the present invention.

Fig. 7 is a schematic diagram of an anodic oxidation process according to an embodiment of the present invention.

FIG. 8 is a schematic diagram showing that the metal film layer in contact with the electrolyte is completely oxidized into an insulating film in an embodiment of the present invention.

FIG. 9 is a schematic diagram of an oxide thin film transistor in an embodiment of the present invention.

FIG. 10 is a transfer characteristic curve of the oxide thin film transistor prepared in Example 1. FIG.

FIG. 11 is a transfer characteristic curve of the oxide thin film transistor prepared in Example 2.

FIG. 12 is a transfer characteristic curve of the oxide thin film transistor prepared in Comparative Example 1. FIG.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific embodiments described here are only used to explain the present invention, and do not limit the protection scope of the present invention.

The following embodiment is a detailed description of the structure and preparation method of the metal oxide thin film transistor. It can be understood that in other embodiments, the structural layers such as the gate, the gate insulating layer, the semiconductor active layer, the source electrode, and the drain electrode are Oxide thin film transistors with other thicknesses, or oxide thin film transistors whose gate insulating layer and semiconductor active layer contain other materials, can also be prepared according to a similar preparation method, which will not be repeated here.

Oxide thin film transistor of the present invention and preparation method thereof are as follows:

A metal oxide thin film transistor, as shown in FIG. 9, the metal oxide thin film transistor is a bottom gate top contact structure, including a substrate 00, a gate 01, a gate insulating layer 02, a semiconductor active layer 03, a source electrode 04a, The drain electrode 04b and the oxide insulating film layer 06.

The device structure adopted in the embodiment of the present invention is a BCE structure, which has the advantage of simple structure. The relative positions of the structural layers of the oxide thin film transistor are as follows: the gate 01 is located on the substrate 00, the gate insulating layer 02 is located on the gate 01, the semiconductor active layer 03 is located on the gate insulating layer 02, and the source electrode , The drain electrode is located at both ends of the semiconductor active layer 03 and separated by an oxide insulating film layer 06 , and the oxide insulating film layer 06 is located on the semiconductor active layer 03 .

In the embodiment of the present invention, the source electrode 04a, the drain electrode 04b and the oxide insulating film layer 06 are prepared by oxidizing the metal conductive film above the back channel of the semiconductor active layer by anodic oxidation, which is different from the traditional preparation method. The invention has the advantages of simple process, no damage to the semiconductor active layer, suitable for industrial production and the like.

Specifically, the manufacturing process of the metal oxide thin film transistor described in the embodiment of the present invention is shown in Figures 1 to 9, including the following steps:

Select substrate 00;

forming a gate 01 on the substrate;

forming a gate insulating layer 02 on the gate;

forming a semiconductor active layer 03 on the gate insulating layer;

Forming a metal conductive thin film layer 04 on the semiconductor active layer, the metal conductive thin film layer is provided with a source electrode region, a drain electrode region and an insulating region;

Form a photoresist 05 on the metal conductive film layer, pattern it by photolithography, expose the insulating region, and form a source electrode protection layer and a drain electrode on the source electrode region and the drain electrode region respectively Protective layer, obtains containing protective layer device;

placing the protective layer-containing device in an electrolyte, and completely oxidizing the insulating region by anodic oxidation to form an oxide insulating film layer 06;

The substrate containing the oxide insulating thin film layer is taken out, and the source electrode protection layer and the drain electrode protection layer are removed to obtain an oxide thin film transistor.

More specifically, the preparation of the metal oxide thin film transistor described in the embodiment of the present invention includes the following steps:

(1) Select substrate 00.

(2) Prepare a layer of conductive film with a thickness of 100-500 nm on the substrate 00 by sputtering, and prepare the gate 01 by patterning with a blocking mask or photolithography.

(3) Prepare a thin film with a thickness of 100-1000 nm on the upper part of the gate 01 by anodic oxidation, thermal oxidation, physical vapor deposition or chemical vapor deposition, and pattern it by blocking mask or photolithography A gate insulating layer 02 is prepared.

(4) Prepare a thin film with a thickness of 10-100 nm by sputtering, and pattern the semiconductor active layer by masking.

(5) Prepare a metal conductive film layer 04 with a thickness of 40 to 70 nm on the semiconductor active layer by magnetron sputtering, and the metal conductive film layer is provided with a source electrode region, a drain electrode region and an insulating layer. area.

(6) Prepare a layer of photoresist 05 with a thickness of 500-1200nm on the metal conductive film 04 by spin coating, pattern it by photolithography to expose the insulating region, and place it on the source electrode A source electrode protection layer and a drain electrode protection layer are respectively formed in the region and the drain electrode region to obtain a device containing the protection layer.

(7) The device containing the protection layer is placed in an electrolyte solution, and the insulating region is completely oxidized by anodic oxidation to form an oxide insulating film layer 06 .

Wherein, the anodic oxidation is: the device containing the protective layer is connected to the anode, the Pt is connected to the cathode, and a constant current of 0.1-1mA/ ^cm2 is applied for oxidation. When the voltage between the two electrodes reaches a set value of 70-150V, the constant voltage oxidation to no change in current.

(8) Take out the substrate containing the oxide insulating thin film layer, remove the source electrode protection layer and the drain electrode protection layer, and obtain an oxide thin film transistor.

The method prepared by the invention has no pollution at the interface between the source electrode, the drain electrode and the semiconductor active layer, has few defects, does not cause damage to the semiconductor active layer, does not need to etch the barrier layer additionally, has simple process and low production cost. In addition, the metal conductive film layer above the back channel of the semiconductor active layer is oxidized into a metal oxide insulating film layer, which can be used as a passivation layer to protect the semiconductor active layer from the influence of water, oxygen and other atmospheres in the air. The present invention does not require additional preparation of a passivation layer, and saves the cumbersome preparation process of the passivation layer.

In a word, the preparation method of the oxide thin film crystal of the present invention has the characteristics of simple process, no damage to the semiconductor active layer, low cost, suitable for industrial production and the like.

Example 1

A metal oxide thin film transistor, as shown in FIG. 9, the metal oxide thin film transistor is a bottom gate top contact structure, including a substrate 00, a gate 01, a gate insulating layer 02, a semiconductor active layer 03, a source electrode 04a, The drain electrode 04b and the oxide insulating film layer 06.

The device structure adopted in this embodiment is a BCE structure, which has the advantage of simple structure. The relative positions of the structural layers of the oxide thin film transistor are as follows: the gate 01 is located on the substrate 00, the gate insulating layer 02 is located on the gate 01, the semiconductor active layer 03 is located on the gate insulating layer 02, and the source electrode , The drain electrode is located at both ends of the semiconductor active layer 03 and separated by an oxide insulating film layer 06 , and the oxide insulating film layer 06 is located on the semiconductor active layer 03 .

In this embodiment, the source electrode 04a, the drain electrode 04b and the oxide insulating film layer 06 are prepared by oxidizing the metal conductive film above the back channel of the semiconductor active layer by anodic oxidation, which is different from the traditional preparation method and has The process is simple, no damage to the semiconductor active layer, suitable for industrial production and the like.

The metal oxide thin film transistor described in this embodiment is prepared by the following steps:

(1) Select substrate 00.

(2) Prepare a conductive thin film with a thickness of 200 nm on the substrate 00 by sputtering, and pattern the gate 01 by photolithography.

(3) A thin film with a thickness of 140 nm is prepared on the upper part of the gate 01 by anodic oxidation, and a gate insulating layer 02 is prepared by patterning with a mask or photolithography. In this embodiment, the material of the gate insulating layer is Al ₂ O ₃ .

(4) Prepare a thin film with a thickness of 40 nm by sputtering, and pattern the semiconductor active layer by masking. In this embodiment, the material of the semiconductor active layer is binary oxide ZnO.

(5) Prepare a metal conductive film layer 04 with a thickness of 50 nm on the semiconductor active layer by magnetron sputtering, and the metal conductive film layer is provided with a source electrode region, a drain electrode region and an insulating region. In this embodiment, the material of the metal conductive thin film layer is Al.

(6) Prepare a layer of photoresist 05 with a thickness of 1000nm on the metal conductive film 04 by spin coating, and pattern it by photolithography to expose the insulating region, and in the source electrode region and The source electrode protection layer and the drain electrode protection layer are respectively formed in the drain electrode region, and a device containing the protection layer is obtained.

(7) The device containing the protective layer is placed in an electrolyte solution, and the insulating region is completely oxidized by anodic oxidation to form an oxide insulating film layer 06 . The material of the oxide insulating film layer is Al ₂ O ₃ ;

Wherein, the anodic oxidation is as follows: the device containing the protective layer is connected to the anode, the Pt is connected to the cathode, and a constant current of 0.15A/ ^cm2 is added to oxidize, the voltage between the two electrodes will increase linearly with time, and when the voltage between the two electrodes reaches When the set value (Vc=70V), and then keep the voltage constant, the current will continue to decrease with time until the current has almost no obvious change, and the duration of this process is about 10-15min.

In this embodiment, the electrolyte is an aqueous solution of ammonium tartrate and ethylene glycol, wherein the mass fraction of ammonium tartrate is 3.48 wt%, and the volume ratio of ammonium tartrate to ethylene glycol is 1:3.

(8) Take out the substrate containing the oxide insulating thin film layer, remove the source electrode protection layer and the drain electrode protection layer, and obtain an oxide thin film transistor.

The performance of the thin film transistor device prepared in Example 1 was tested in air. FIG. 10 is a measured transfer characteristic curve of the thin film transistor prepared in Example 1, that is, the relationship between the drain current and the gate voltage. The test conditions of the curve are: the source voltage (VS) is 0V, the drain voltage (VD) is constant at 20V, the gate voltage (VG) is swept from -20V to 20V, and the drain current (ID) is tested.

It can be seen from the figure that the thin film transistor device prepared in this embodiment shows good switching performance, which shows that the insulating region of the metal conductive film layer is completely oxidized into an oxide insulating film during the anodic oxidation process. Therefore, the device has Obvious field effect characteristics.

Example 2

A metal oxide thin film transistor, as shown in FIG. 9, the metal oxide thin film transistor is a bottom gate top contact structure, including a substrate 00, a gate 01, a gate insulating layer 02, a semiconductor active layer 03, a source electrode 04a, The drain electrode 04b and the oxide insulating film layer 06.

The device structure adopted in this embodiment is a BCE structure, which has the advantage of simple structure. The relative positions of the structural layers of the oxide thin film transistor are as follows: the gate 01 is located on the substrate 00, the gate insulating layer 02 is located on the gate 01, the semiconductor active layer 03 is located on the gate insulating layer 02, and the source electrode , The drain electrode is located at both ends of the semiconductor active layer 03 and separated by an oxide insulating film layer 06 , and the oxide insulating film layer 06 is located on the semiconductor active layer 03 .

In this embodiment, the source electrode 04a, the drain electrode 04b and the oxide insulating film layer 06 are prepared by oxidizing the metal conductive film above the back channel of the semiconductor active layer by anodic oxidation, which is different from the traditional preparation method and has The process is simple, no damage to the semiconductor active layer, suitable for industrial production and the like.

The metal oxide thin film transistor described in this embodiment is prepared by the following steps:

(1) Select substrate 00.

(2) Prepare a layer of conductive film with a thickness of 100 nm on the substrate 00 by sputtering, and prepare the gate 01 by patterning with a blocking mask.

(3) A thin film with a thickness of 100 nm is prepared on the upper part of the gate 01 by physical vapor deposition, and a gate insulating layer 02 is prepared by patterning by means of a blocking mask. In this embodiment, the material of the gate insulating layer is Ta ₂ O ₅ .

(4) A thin film with a thickness of 10 nm was prepared by sputtering, and a semiconductor active layer was obtained by patterning by a blocking mask method. In this embodiment, the material of the semiconductor active layer is ternary oxide InZnO.

(5) Prepare a metal conductive film layer 04 with a thickness of 10 nm on the semiconductor active layer by magnetron sputtering, and the metal conductive film layer is provided with a source electrode region, a drain electrode region and an insulating region. In this embodiment, the material of the metal conductive film layer is Ta.

(6) Prepare a layer of photoresist 05 with a thickness of 500nm on the metal conductive film 04 by spin coating, pattern it by photolithography, expose the insulating region, and place on the source electrode region and The source electrode protection layer and the drain electrode protection layer are respectively formed in the drain electrode region, and a device containing the protection layer is obtained.

(7) The device containing the protection layer is placed in an electrolyte solution, and the insulating region is completely oxidized by anodic oxidation to form an oxide insulating film layer 06 . The material of the oxide insulating film layer is Ta ₂ O ₅ .

Wherein, the anodic oxidation is as follows: the device containing the protective layer is connected to the anode, the Pt is connected to the cathode, and a constant current of 1mA/cm is added for oxidation, and when the voltage between the ^two electrodes reaches a set value (Vc=150V), the voltage is then kept constant , the current will continue to decrease with time until there is almost no significant change in the current.

In this embodiment, the electrolyte is an aqueous solution of ammonium tartrate and ethylene glycol, wherein the mass fraction of ammonium tartrate is 3.48 wt%, and the volume ratio of ammonium tartrate to ethylene glycol is 1:3.

(8) Take out the substrate containing the oxide insulating thin film layer, remove the source electrode protection layer and the drain electrode protection layer, and obtain an oxide thin film transistor.

The performance of the thin film transistor device prepared in this embodiment was tested in the air, and the test conditions were the same as those in embodiment 1. The measured transfer characteristic curve of the thin film transistor prepared in embodiment 2 is shown in FIG. 11 .

It can be seen from the figure that the thin film transistor device prepared in this embodiment also exhibits good switching performance, which shows that the insulating region of the metal conductive film is completely oxidized into an oxide insulating film during the anodic oxidation process, so the device has Obvious field effect characteristics.

Comparative example 1

An oxide thin film transistor was prepared with reference to the preparation method described in Example 1. The preparation process was basically the same as that of Example 1, the only difference being that the voltage Vc in step (7) was set to 50V in this comparative example.

The performance of the thin film transistor device prepared in this comparative example was tested in air under the same test conditions as those in Example 1. The transfer characteristic curve measured for the thin film transistor prepared in Comparative Example 1 is shown in FIG. 12 .

It can be seen from the figure that the device in this comparative example does not have switching performance and exhibits resistance characteristics, which shows that the insulating region of the metal conductive film is not completely oxidized into an oxide insulating film during the anodic oxidation process, so the source electrode of the device, The drain electrode is turned on and cannot be turned off.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. An oxide thin film transistor, characterized in that it comprises: a substrate, a gate, a gate insulating layer, a semiconductor active layer, a source electrode, and a drain electrode; the gate is located on the substrate, and the gate insulation layer is located on the gate, the semiconductor active layer is located on the gate insulating layer, and the source electrode and the drain electrode are located on the semiconductor active layer and separated by an oxide insulating film layer. 2 . The oxide thin film transistor according to claim 1 , wherein the material of the oxide insulating thin film layer is an oxide of Al ₂ O ₃ , Ta ₂ O ₅ , CuO or Al—Nd. 3. The oxide thin film transistor according to claim 1, characterized in that, the material of the source electrode and the drain electrode is Al, Ta, Cu or Al-Nd. 4. The oxide thin film transistor according to claim 3, wherein the thicknesses of the source electrode and the drain electrode are respectively 10-500 nm. 5. The oxide thin film transistor according to any one of claims 1-4, characterized in that the material of the semiconductor active layer is binary oxide and/or multi-component oxide. 6. The oxide thin film transistor according to claim 5, wherein the semiconductor active layer has a thickness of 10-100 nm. 7. The method for preparing the oxide thin film transistor according to any one of claims 1-6, characterized in that it comprises the following steps: Select the substrate; forming a gate on the substrate; forming a gate insulating layer on the gate; forming a semiconductor active layer on the gate insulating layer; forming a metal conductive thin film layer on the semiconductor active layer, the metal conductive thin film layer is provided with a source electrode region, a drain electrode region and an insulating region; Form a photoresist on the metal conductive film layer, pattern it by photolithography, expose the insulating region, and form a source electrode protection layer and a drain electrode protection layer on the source electrode region and the drain electrode region respectively layer, to obtain a protective layer device; placing the protective layer-containing device in an electrolyte solution, and completely oxidizing the insulating region by anodic oxidation to form an oxide insulating film layer; The substrate containing the oxide insulating thin film layer is taken out, and the source electrode protection layer and the drain electrode protection layer are removed to obtain an oxide thin film transistor. 8. The preparation method according to claim ⁷ , wherein the anodic oxidation is as follows: the device containing the protective layer is an anode, Pt is a cathode, and a constant current of 0.1 to 1mA/cm is added to oxidize it. When the voltage reaches the set value of 70-150V, then the constant voltage is oxidized until the current has no change. 9. preparation method according to claim 8 is characterized in that, described electrolytic solution is the aqueous solution of ammonium tartrate and ethylene glycol, and wherein the massfraction of ammonium tartrate is 3.48wt%, and the volume ratio of ammonium tartrate and ethylene glycol It is 1:3. 10. The preparation method according to claim 9, characterized in that the photoresist has a thickness of 500-1200 nm.