阅读说明：本技术 一种短沟道ZnO薄膜晶体管及其制备方法 (Short-channel ZnO thin film transistor and preparation method thereof ) 是由 刘昌� 李思哲 吴昊 陈雪 于 2021-06-21 设计创作，主要内容包括：本申请涉及短沟道ZnO薄膜晶体管及其制备方法,该制备方法包括如下步骤：在真空、惰性气体保护条件下,于第一温度下,在导电衬底上依次沉积栅绝缘层和ZnO沟道层；对所述ZnO沟道层进行光刻,以形成ZnO沟道结构,得到第一结构；对第一结构进行光刻,并依次蒸镀金属附着层和金属覆盖层,以形成源漏双层电极,得到短沟道ZnO薄膜晶体管,所述短沟道ZnO薄膜晶体管的沟道长度L为2nm～3μm。本申请制造出来的ZnO薄膜晶体管具有短沟道,从而降低了ZnO薄膜晶体管的尺寸,同时具备高性能,可以用于驱动Micro-LED。(The application relates to a short-channel ZnO thin film transistor and a preparation method thereof, wherein the preparation method comprises the following steps: sequentially depositing a gate insulating layer and a ZnO channel layer on a conductive substrate at a first temperature under the protection of vacuum and inert gas; photoetching the ZnO channel layer to form a ZnO channel structure to obtain a first structure; and photoetching the first structure, and evaporating the metal adhesion layer and the metal covering layer in sequence to form a source-drain double-layer electrode to obtain the short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 2 nm-3 mu m. The ZnO thin film transistor manufactured by the application has a short channel, so that the size of the ZnO thin film transistor is reduced, and the ZnO thin film transistor has high performance and can be used for driving a Micro-LED.)

1. A preparation method of a short-channel ZnO thin film transistor is characterized by comprising the following steps:

sequentially depositing a gate insulating layer (2) and a ZnO channel layer (3) on a conductive substrate (1) at a first temperature under the protection of vacuum and inert gas;

photoetching is carried out on the ZnO channel layer (3) to form a ZnO channel structure (4) so as to obtain a first structure;

and photoetching the first structure, and evaporating a metal adhesion layer (5) and a metal covering layer (6) in sequence to form a source-drain double-layer electrode (7) to obtain the short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 2 nm-3 mu m.

2. The method of manufacturing a short channel ZnO thin film transistor of claim 1, wherein: the channel length L of the short-channel ZnO thin film transistor is 100 nm-2 mu m.

3. The method of manufacturing a short channel ZnO thin film transistor of claim 1, wherein:

the metal adhesion layer (5) adopts one or more of Ti, Mo, Al, Zn and Sn;

and/or one or more of Cu, Ag and Au is/are adopted as the metal covering layer (6).

4. The method of manufacturing a short channel ZnO thin film transistor of claim 1, wherein:

the thickness of the metal adhesion layer (5) is 2 nm-100 nm;

and/or the thickness of the metal covering layer (6) is 2 nm-150 nm.

5. The method of manufacturing a short channel ZnO thin film transistor of claim 1, wherein:

the channel width W of the short-channel ZnO thin film transistor is 2 nm-3 mu m;

and/or the ZnO channel layer (3) is 2 nm-50 nm thick.

6. The method of manufacturing a short channel ZnO thin film transistor of claim 1, wherein: the first temperature is 20-145 ℃.

7. The method of manufacturing a short channel ZnO thin film transistor of claim 6, wherein: the first temperature is 130-145 ℃.

8. The method of manufacturing a short channel ZnO thin film transistor of claim 1, wherein: the thickness of the gate insulating layer (2) is 2 nm-60 nm.

9. The method of manufacturing a short channel ZnO thin film transistor of claim 1, wherein: the gate insulating layer (2) is Al₂O₃、HfO₂、SiO₂、ZrO₂、Ta₂O₅、La₂O₃And TiO₂One kind of (1).

10. A short channel ZnO thin film transistor, comprising: which is prepared by the method for preparing a short-channel ZnO thin film transistor according to any one of claims 1 to 9.

Technical Field

The application relates to the technical field of semiconductor devices, in particular to a short-channel ZnO thin film transistor and a preparation method thereof.

Background

Micro-LED display is a novel self-luminous display technology, and is known as a next generation display technology due to its high resolution, high brightness, high color rendering, low power consumption, fast response speed, long service life, and comprehensive performance far superior to Liquid Crystal Display (LCD) and organic light emitting diode display (OLED).

The Micro-LEDs are mainly driven by Thin Film Transistors (TFTs), and since each TFT drives one Micro-LED, the size of a single TFT is required to be reduced to 5 μm or less. To ensure that the thin film transistor TFT can effectively drive the Micro-LED, it is necessary to reduce the size of the thin film transistor TFT.

Therefore, it is an urgent problem to reduce the size of the TFT and provide high performance for driving the Micro-LED.

Disclosure of Invention

The embodiment of the application provides a short-channel ZnO thin film transistor and a preparation method thereof, and the manufactured ZnO thin film transistor has a short channel, so that the size of the ZnO thin film transistor is reduced, and the ZnO thin film transistor has high performance and can be used for driving a Micro-LED.

In a first aspect, a method for preparing a short-channel ZnO thin film transistor is provided, which comprises the following steps:

sequentially depositing a gate insulating layer and a ZnO channel layer on a conductive substrate at a first temperature under the protection of vacuum and inert gas;

photoetching the ZnO channel layer to form a ZnO channel structure to obtain a first structure;

and photoetching the first structure, and evaporating the metal adhesion layer and the metal covering layer in sequence to form a source-drain double-layer electrode to obtain the short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 2 nm-3 mu m.

In some embodiments, the channel length L of the short-channel ZnO thin film transistor is 100 nm-2 μm.

In some embodiments, the metal adhesion layer employs one or more of Ti, Mo, Al, Zn, and Sn;

and/or the metal covering layer adopts one or more of Cu, Ag and Au.

In some embodiments, the metal adhesion layer has a thickness of 2nm to 100 nm;

and/or the thickness of the metal covering layer is 2 nm-150 nm.

In some embodiments, the channel width W of the short-channel ZnO thin film transistor is 2 nm-3 μm;

and/or the ZnO channel layer has a thickness of 2nm to 50 nm.

In some embodiments, the first temperature is 20 ℃ to 145 ℃.

In some embodiments, the first temperature is 130 ℃ to 145 ℃.

In some embodiments, the gate insulating layer has a thickness of 2nm to 60 nm.

In some embodiments, the gate insulating layer is Al₂O₃、HfO₂、SiO₂、ZrO₂、Ta₂O₅、La₂O₃And TiO₂One kind of (1).

In a second aspect, a short-channel ZnO thin film transistor is provided, which is prepared by any of the above-mentioned methods for preparing a short-channel ZnO thin film transistor.

The beneficial effect that technical scheme that this application provided brought includes:

according to the method, the relation between the channel size and each performance index of the ZnO thin film transistor is explored by reducing the channel size, the contact resistance is reduced by using the double-layer electrode, the channel resistance is reduced by optimizing the growth process, and therefore the high-performance short-channel ZnO thin film transistor capable of driving the Micro-LED is prepared, when the channel length is 2 nm-3 mu m, the mobility of the ZnO thin film transistor is higher than 30cm²V^-1s^-1The subthreshold swing is 0.21-0.96V/dec, the on-off ratio is 1.42 multiplied by 10⁶～1.93×10⁹The threshold voltage is between-1.12V and 2V, and the overall comprehensive performance is high.

When the channel length is 100 nm-2 mu m, the mobility of the ZnO thin film transistor is as high as 58.9-75.8 cm²V^-1s^-1The subthreshold swing is as low as 0.21-0.25V/dec, and the on-off ratio is as high as 1.56 x 10⁹～1.93×10⁹And the threshold voltage is between 1-2V, thus completely meeting the commercial requirement.

The high-performance short-channel ZnO thin film transistor has the advantages that the metal adhesion layer of the ZnO thin film transistor electrode has good adhesion and low metal work function, good ohmic contact can be formed with the ZnO thin film, the high-quality channel thin film is formed by a growth window, the channel resistance is low, the short-channel effect is compensated in the channel length within a certain range by the process means, and therefore even when the channel length is only 100 nm-2 mu m, the mobility, the subthreshold swing and the on-off ratio of the ZnO thin film transistor are kept high, the threshold voltage is 1-2V, and the commercial requirements are completely met.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic view of a conductive substrate deposited with a gate insulating layer and a ZnO channel layer according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a first structure provided in an embodiment of the present application;

FIG. 3 is a schematic view of a short channel ZnO TFT according to an embodiment of the present disclosure;

FIG. 4 is a schematic view of another short channel ZnO TFT in accordance with an embodiment of the present disclosure;

FIG. 5 is a top view of a short channel ZnO TFT microscope provided in an embodiment of the present application;

FIG. 6 is a transfer characteristic curve of a short channel ZnO thin film transistor with a channel length of 100nm and Cu/Ti source-drain double-layer electrodes according to an embodiment of the present application;

fig. 7 is a change curve of the mobility, the sub-threshold swing, and the threshold voltage of the short channel ZnO thin film transistor of the Cu/Ti source drain bilayer electrode provided in the embodiment of the present application with the reduction of the channel length.

In the figure: 1. a conductive substrate; 2. a gate insulating layer; 3. a ZnO channel layer; 4. a ZnO channel structure; 5. a metal adhesion layer; 6. a metal cap layer; 7. and a source-drain double-layer electrode.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Referring to fig. 1, fig. 2, fig. 3, and fig. 4, a method for manufacturing a short-channel ZnO thin film transistor according to an embodiment of the present disclosure includes the following steps:

step 1, selecting a heavily doped conductive substrate 1, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

And 2, putting the conductive substrate 1 into an ALD (atomic layer deposition) chamber, vacuumizing, heating to a first temperature under the protection of inert gases such as high-purity nitrogen and the like, and sequentially depositing a gate insulating layer 2 and a ZnO channel layer 3 on the conductive substrate 1.

And 3, spin-coating positive photoresist on the conductive substrate 1 deposited with the gate insulating layer 2 and the ZnO channel layer 3 through a spin coater, then placing the conductive substrate on a hot table for baking, aligning a mask plate with the conductive substrate 1, performing ultraviolet exposure, and then placing the conductive substrate in positive photoresist developer for developing. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer 3, removing the photoresist, and forming a ZnO channel structure 4 to obtain a first structure.

And 4, spin-coating negative glue on the first structure by using a spin coater, and then placing the structure on a hot table for baking. Aligning an electrode structure in a mask plate with a ZnO channel structure 4 on a conductive substrate 1, carrying out ultraviolet exposure for 15s, baking on the mask plate on a hot table, developing in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1, sequentially evaporating a metal adhesion layer 5 and a metal covering layer 6, placing the conductive substrate 1 deposited with the evaporated metal adhesion layer 5 and the metal covering layer 6 in acetone by adopting a stripping method, treating photoresist to form a source-drain double-layer electrode 7, cleaning in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 2 nm-3 mu m.

Referring to fig. 5, the length L of the prepared short channel ZnO thin film transistor channel is from 2nm to 50nm, and the width W is 50 nm.

In the step 2, the first temperature is 20 ℃ to 145 ℃. If the temperature is higher than 145 ℃, the oxygen vacancy concentration is higher as the temperature is higher, so that the carrier concentration is higher, and the ZnO thin film transistor cannot be turned off when the carrier concentration is too high, so that the off-state current is high, and the switching ratio of the ZnO thin film transistor is reduced, whereas if the temperature is lower than 20 ℃, the film growth quality is not high, so that the channel resistance is higher, and the mobility is reduced.

In the step 2, the first temperature is preferably 130 to 145 ℃.

In the step 4, the channel length L of the short-channel ZnO thin film transistor is preferably 100nm to 2 μm.

In the step 4, the channel width W of the short-channel ZnO thin film transistor is 2 nm-3 μm.

In the step 2, when the gate insulating layer 2 and the ZnO channel layer 3 are deposited, an in-situ growth method is adopted, so that the vacuum environment can be prevented from being damaged, the interface between the gate insulating layer 2 and the ZnO channel layer 3 is improved, and the subthreshold swing amplitude can be reduced.

In the step 2, the thickness of the gate insulating layer 2 is 2nm to 60 nm. The ZnO channel layer 3 has a thickness of 2nm to 50 nm.

In the step 2, the gate insulating layer 2 is Al₂O₃、HfO₂、SiO₂、ZrO₂、Ta₂O₅、La₂O₃And TiO₂One kind of (1).

In the step 2, diethyl zinc and water are used as the precursor sources of ZnO.

In the step 4, a double-layer motor design is adopted, the adhesion of the electrode is improved through the metal adhesion layer 5, the contact resistance between the ZnO channel layer 3 and the electrode is reduced, and the high conductivity of the electrode is ensured through the metal covering layer 6.

In the step 4, the metal adhesion layer 5 is one or more of Ti, Mo, Al, Zn, and Sn, and the metal capping layer 6 is one or more of Cu, Ag, and Au.

In the step 4, the thickness of the metal adhesion layer 5 is 2nm to 100nm, and the thickness of the metal covering layer 6 is 2nm to 150 nm.

Example 1

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, placing the conductive substrate into an ALD chamber, vacuumizing, heating to 20 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 200 nm.

Example 2

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, placing the conductive substrate into an ALD chamber, vacuumizing, heating to 50 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 200 nm.

Example 3

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, placing the conductive substrate into an ALD chamber, vacuumizing, heating to 80 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 200 nm.

Example 4

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 110 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 200 nm.

Example 5

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 120 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 200 nm.

Example 6

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 125 ℃ under the protection of high-purity nitrogen, and firstly placing the conductive substrate on the conductive substrateWith Trimethylaluminium (TMA) and water (H)₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 200 nm.

Example 7

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 130 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃A gate insulating layer, and a precursor source is used as the second precursor source without breaking vacuumEthyl Zinc (DEZ) and water (H)₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 200 nm.

Example 8

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 140 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 200 nm.

Example 9

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 145 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 200 nm.

Example 10

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 140 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 2 nm.

Example 11

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 140 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, treating photoresist to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 10 nm.

Example 12

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 140 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, treating photoresist to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 80 nm.

Example 13

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 140 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, treating photoresist to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 90 nm.

Example 14

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 140 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 100 nm.

Referring to FIG. 6, it can be seen that the ZnO TFT has a low off-state current and a mobility as high as 63.8cm for the transfer characteristic curve of the short-channel ZnO TFT with a channel length L of 100nm and a width W of 50nm²V^-1s^-1The subthreshold swing is as low as 0.25V/dec, the threshold voltage is 1.13V, and the switching ratio reaches 1.88 multiplied by 10⁹. The mobility, subthreshold swing and threshold voltage of the short channel ZnO thin film transistor are shown as the variation curves of the channel length reduction. It can be seen that the mobility does not deteriorate with decreasing channel length.

Example 15

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 140 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, treating photoresist to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 500 nm.

Example 16

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 140 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, treating photoresist to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 1000 nm.

Example 17

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 140 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, treating photoresist to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 2000 nm.

Example 18

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 140 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, treating photoresist to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 2500 nm.

Example 19

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 140 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, treating photoresist to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 3000 nm.

Comparative example 1

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, placing the conductive substrate into an ALD chamber, vacuumizing, heating to 15 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 200 nm.

Comparative example 2

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, and keeping the conductive substrate in high-purity nitrogenUnder the protection condition, heating to 150 ℃, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃The gate insulating layer is formed by re-using diethyl zinc (DEZ) and water (H) as precursor source without breaking vacuum₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And then aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthofilm developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 200 nm.

Comparative example 3

A preparation method of a short-channel ZnO thin film transistor comprises the following steps:

step 1, selecting a heavily doped conductive substrate, putting the conductive substrate into acetone for ultrasonic treatment for 10min, then putting the conductive substrate into ethanol for ultrasonic treatment for 10min, and finally drying the conductive substrate by using nitrogen.

Step 2, putting the conductive substrate into an ALD chamber, vacuumizing, heating to 140 ℃ under the protection of high-purity nitrogen, and firstly using trimethyl aluminum (TMA) and water (H) on the conductive substrate₂O) precursor Source growth of 10nm thick Al₂O₃A gate insulating layer is formed on the gate insulating layer,without breaking vacuum, the re-use precursor sources are diethyl zinc (DEZ) and water (H)₂O) growing a 5nm thick ZnO channel layer.

And 3, spin-coating positive photoresist on the conductive substrate deposited with the gate insulating layer and the ZnO channel layer by a spin coater at the speed of 600r/min for 3S and at the speed of 4000r/min for 60S S1813. And then baking the mask plate on a hot table at 120 ℃ for 2min, aligning the mask plate with the conductive substrate, performing ultraviolet exposure, and then developing the mask plate in an orthofilm developer. And then putting the ZnO channel layer into phosphoric acid for corrosion, putting the ZnO channel layer into acetone after etching the redundant ZnO channel layer, removing the photoresist, and forming a ZnO channel structure to obtain a first structure.

And 4, spin-coating the negative photoresist N4340 on the first structure by using a spin coater, wherein the spin coater speed is 600r/min for 3s, and the spin coater speed is 2000r/min for 100 s. Then baking at 70 deg.C for 1 min. And aligning an electrode structure in a mask plate with a ZnO channel structure on a conductive substrate, performing ultraviolet exposure for 15s, baking for 3min after placing the mask plate on a hot table at 100 ℃, then placing the mask plate in a solution prepared from an orthogel developing solution and deionized water in a ratio of 1:1 for developing for 2min, then sequentially evaporating 5nm Ti and 30nm Cu, placing the conductive substrate deposited with the Ti and the Cu in acetone by adopting a stripping method, processing photoresist cleanly to form a source-drain double-layer electrode, cleaning the conductive substrate in ethanol to obtain a short-channel ZnO thin film transistor, wherein the channel length L of the short-channel ZnO thin film transistor is 3100 nm.

Table 1: performance of short channel ZnO thin film transistor prepared in each example and comparative example

Note: s represents 'embodiment', for example S1 is embodiment 1; d represents "comparative example" and D1 is comparative example 1.

As each thin film transistor TFT drives one Micro-LED, the size of the thin film transistor TFT is required to be reduced to be less than 5 mu m by the Micro-LED along with the increasing number of pixel points of the Micro-LED, and the size of the thin film transistor TFT is inevitably required to be reduced in order to ensure that the thin film transistor TFT can effectively drive the Micro-LED.

The inventors have found, after studying the related art, that the size of the thin film transistor TFT can be reduced by reducing the channel length of the thin film transistor TFT.

However, the inventors have further found through experiments that the mobility of the thin film transistor TFT is to be brought to a high level such as 30cm²V^-1s^-1While the above-mentioned channel lengths are all 20 μm or more, it is necessary to make the size of the thin film transistor TFT larger, and if the channel length is reduced, the mobility is reduced due to the contact resistance and the channel resistance which cannot be ignored, for example, when the channel length is reduced to 5 μm, the mobility is reduced to 11.6cm²V^-1s^-1The Micro-LED cannot be driven efficiently.

Through further analysis by the inventor, the reason may be caused by short channel effect, that is, as the channel length is reduced, the performance degradation of the ZnO thin film transistor caused by the short channel effect becomes non-negligible.

Based on this, in combination with comparative examples D1, D2, and examples S1 to S9, the inventors further investigated that when the growth temperature was controlled at 20 ℃ to 145 ℃, even if the channel length was reduced to 200nm, the obtained ZnO thin film transistor was prepared with a mobility reduced to 11.6cm, compared to that after being currently reduced to 5 μm²V^-1s^-1The mobility of the polymer can be obviously improved to 30cm²V^{- 1}s^-1Above, reach 69.2cm²V^-1s^-1Meanwhile, the threshold voltage is between 1V and 2V, and the commercial standard is met.

If the growth temperature is reduced to 15 ℃, the mobility of the ZnO thin film transistor can be greatly reduced due to large channel resistance caused by low film quality level, in addition, the poor interface quality of an insulating layer and a channel layer is caused by low temperature, so that the sub-threshold swing amplitude is degraded, the carrier concentration of a channel is low, the threshold voltage is overlarge, and the energy consumption of the ZnO thin film transistor is increased; if the growth temperature is increased to 150 ℃, the channel carrier concentration is too high along with the temperature increase, so that the off-state current becomes large, the on-off ratio is reduced, and the threshold voltage is shifted to below 1V due to the high carrier concentration, so that the ZnO thin film transistor is not stable enough for commercial application. Therefore, the Micro-LED can not be effectively driven by preparing the ZnO thin film transistor at too low or too high temperature.

Meanwhile, the growth temperature is only improved to 45.4cm compared with 20-130 ℃ in the study of the growth temperature²V^-1s^-1When the temperature is 130-145 ℃, the mobility can be further improved to reach 69.2cm²V^-1s^-1。

Based on the above temperature examination, in combination with comparative example D3 and examples S10 to S19, the inventors further investigated and found that when the channel length was controlled to 100nm to 2 μm, the ZnO thin film transistor performance remained high and was commercially advantageous. When the channel size is reduced to be less than 100nm, the effective channel length is shorter than the actual channel length, so that the charge quantity required for opening the ZnO thin film transistor is greatly reduced, the threshold voltage is negatively shifted to be less than 1V, and the ZnO thin film transistor has certain difficulty in meeting the commercial requirement due to the degraded subthreshold swing; when the channel size is increased to 2 μm or more, the threshold voltage of the ZnO thin film transistor is increased, and the mobility can be improved even at the above growth temperature, for example, 75.8cm can be obtained in example S17²V^-1s^-1And when the channel length exceeds 3 μm, the threshold voltage is greater than 2V, which is also not satisfactory for commercial applications.

Meanwhile, in the research on the channel length, the fact that the film is grown at a proper temperature when the channel length is 100 nm-2 mu m can enable the mobility, the sub-threshold swing amplitude and the on-off ratio of the ZnO thin film transistor to be kept at high levels, and the threshold voltage is between 1V and 2V.

The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.