CN109950321B

CN109950321B - P-type field effect transistor based on tungsten oxide and preparation method thereof

Info

Publication number: CN109950321B
Application number: CN201910225445.2A
Authority: CN
Inventors: 谢伟广; 余冰; 罗志; 卢月恒; 赖浩杰; 陈科球
Original assignee: Jinan University
Current assignee: Jinan University
Priority date: 2019-03-25
Filing date: 2019-03-25
Publication date: 2022-02-11
Anticipated expiration: 2039-03-25
Also published as: CN109950321A

Abstract

The invention relates to a P-type field effect transistor based on tungsten oxide and a preparation method thereof, wherein a solid electrolyte is used as a substrate, a mask plate is placed on the solid electrolyte substrate, and a device channel is reserved; then depositing an insulating film; then taking down the mask plate, and depositing a tungsten trioxide film; then, the mask plate is placed again, and the source electrode and the drain electrode are evaporated; and finally, evaporating and depositing a gate electrode on the back of the solid electrolyte to form the field effect device. According to the invention, tungsten trioxide is used as an active layer and applied to a transistor, Au is used as a source electrode and a drain electrode, the device is prepared by adopting a vacuum thermal evaporation method, the process is simple, meanwhile, a solid electrolyte is used as a gate medium, and due to the extremely strong long-range ion-electron coupling characteristic of the electrolyte, when a gate electrode is far away from a channel region, the extremely strong regulation and control effect on the conductivity of the channel can be still generated, the alignment requirement in the manufacturing process of the device is reduced, and the transistor with the P-type field effect modulation effect is obtained.

Description

P-type field effect transistor based on tungsten oxide and preparation method thereof

Technical Field

The invention relates to the technical field of transistors, in particular to a P-type field effect transistor based on tungsten oxide and a preparation method thereof.

Background

Metal oxide semiconductor materials have been the main subject of research in the field of novel flat panel displays by virtue of their high mobility, high visible light transmittance, and excellent electrical stability. Among the transition metal oxides, tungsten oxide, which is a wide band gap semiconductor material having a forbidden band width of 2.4eV to 3.5eV, has been intensively studied because it has excellent electron transport characteristics, photoelectrochemical properties, photocatalytic properties, etc., particularly in the form of a thin film, and is useful for advanced technical applications. The dielectric constant of the conventional silicon dioxide insulating layer is too small, so that the carrier concentration of a tungsten trioxide thin film channel is often insufficient to show field effect characteristics. How to increase the interface charge density becomes a difficulty in preparing the tungsten trioxide field effect transistor. Research has proved that the addition of a layer of liquid electrolyte such as ionic liquid as gate dielectric in the transistor structure can exhibit electric double-layer phenomenon under electrostatic effect, thereby inducing the carrier concentration of the active layer to increase greatly to form field effect characteristic. However, the ionic liquid has poor stability and difficult preparation process, and device integration cannot be performed, so how to prepare the tungsten oxide thin film transistor compatible with the solid-state electronic device becomes a key obstacle for inhibiting the development of the oxide semiconductor device. On the other hand, currently prepared field effect transistors based on tungsten trioxide are all of an N type, N type and P type field effect devices are needed for manufacturing a complete semiconductor circuit, and the P type field effect devices based on tungsten oxide cannot be realized.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention mainly aims to provide a P-type field effect transistor based on tungsten oxide and a preparation method thereof.

Based on the above purpose, the invention at least provides the following technical scheme:

a preparation method of a P-type field effect transistor based on tungsten oxide comprises the following steps:

providing a solid electrolyte sheet as a substrate;

depositing an insulating film exposing a channel region on one surface of the substrate;

depositing a tungsten trioxide active layer on the insulating film and the channel region;

evaporating a source electrode and a drain electrode on the active layer;

and depositing a gate electrode on the other surface of the substrate.

Further, the solid electrolyte sheet is a lithium ion ceramic.

Further, the thickness of the insulating film is 10-50 nm, and the insulating film is Al₂O₃、SiO₂、Si₃N₄、HfO₂Or ZrO₂。

Further, the tungsten trioxide active layer is an amorphous film, and the thickness of the tungsten trioxide active layer is 100-400 nm.

Further, the thickness of the tungsten trioxide active layer is 300 nm.

Further, the source electrode, the drain electrode and the gate electrode are at least one of Au, Ag and Cu.

Further, the width of the channel region is less than 100 μm.

Further, the deposition of the tungsten trioxide active layer comprises using tungsten trioxide nano powder with purity higher than 99.9% as raw material, and adjusting the pressure of the vacuum evaporation chamber to 4 × 10^-4～5×10^-4Pa, the temperature of the evaporation boat is about 1000 ℃, and tungsten trioxide is evaporated in vacuum.

A tungsten oxide based P-type field effect transistor comprising: the device comprises an insulating film positioned on one surface of a solid electrolyte sheet, wherein a strip-shaped channel region, a tungsten trioxide active layer positioned on the insulating film and the channel region, a source drain electrode positioned on the tungsten trioxide active layer and a gate electrode positioned on the other surface of the solid electrolyte sheet are arranged in the insulating film.

Further, the tungsten trioxide active layer is an amorphous film, the thickness of the tungsten trioxide active layer is 100-400nm, the thickness of the insulating film is 10-50 nm, and the material of the insulating film is Al₂O₃、SiO₂、Si₃N₄、HfO₂Or ZrO₂The width of the channel region is less than 100 μm.

Compared with the prior art, the invention has at least the following beneficial effects:

(1) according to the invention, tungsten trioxide is used as an active layer to be applied to the transistor, the device is manufactured by using a vacuum coating method, the process is simple, the operation is easy to complete, and the method is compatible with the existing integrated circuit process.

(2) The invention takes the solid electrolyte as the gate medium, and because of the extremely strong long-range ion-electron coupling characteristic of the electrolyte, when the gate electrode is far away from the channel region, the invention can still produce extremely strong regulation and control effect on the conductivity of the channel, thereby reducing the alignment requirement in the manufacturing process of the device. Moreover, the solid electrolyte is adopted as a gate medium, so that the transistor with P-type field effect modulation effect is obtained, and the hole mobility is better than 10^-2cm/Vs。

Drawings

FIG. 1 is a schematic diagram of a tungsten oxide-based PFET structure according to the present invention.

Fig. 2 is a graph showing the output characteristics of a tungsten oxide-based pfet according to an embodiment of the present invention.

Fig. 3 is a graph of the transfer characteristics of a tungsten oxide based pfet according to an embodiment of the present invention.

Reference numerals: 01 is a gate electrode, 02 is a solid electrolyte layer, 03 is an insulating layer, 04 is a tungsten trioxide active layer, and 05 is a source and drain electrode.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.

Examples

FIG. 1 is a schematic structural diagram of a P-type field effect transistor based on tungsten oxide according to the present invention, providing a solid electrolyte sheet 02, wherein the solid electrolyte sheet can be lithium ion ceramic, an insulating film 03 is disposed on a surface of the solid electrolyte sheet 02, a thickness of the insulating film 03 is 10-50 nm, and the insulating film 03 is made of Al₂O₃、SiO₂、Si₃N₄、HfO₂Or ZrO₂. The insulating film 03 is provided with stripe-shaped channel regions having a width of less than 100 μm. And the tungsten trioxide active layer 04 is positioned on the insulating film and the channel region, and the tungsten trioxide active layer 04 is an amorphous film and has the thickness of 100-400 nm. And a source-drain electrode 05 on the tungsten trioxide active layer 04, and a gate electrode is provided on the other surface of the solid electrolyte sheet 02. The source/drain electrode and the gate electrode are at least one of Au, Ag and Cu.

The invention takes the solid electrolyte sheet 02 as a gate medium, and because of the extremely strong long-range ion-electron coupling characteristic of the electrolyte, when the gate electrode is far away from a channel region, the invention can still produce extremely strong regulation and control action on the conductivity of the channel, thereby reducing the alignment requirement in the manufacturing process of the device.

Compared with the field effect transistor, the invention also provides a preparation method of the P-type field effect transistor based on the tungsten oxide, which comprises the following steps:

step 1, a solid electrolyte sheet having a size of 5mm, which is a lithium ion ceramic in this example, was taken as a substrate.

Step 2, placing a mask plate with the width of 80 micrometers on the solid electrolyte substrate in the step 1, reserving a channel, and depositing an insulating film layer, wherein in the embodiment, the insulating film layer is aluminum oxide, and in other embodiments, the insulating film layer can be SiO₂、Si₃N₄、HfO₂Or ZrO₂And the like. And taking down the mask plate after the completion. In the step, the insulating film is obtained by taking an aluminum oxide target as a raw material through an atomic layer deposition method, and the deposition thickness is 10-50 nm, preferably 10 nm.

And 3, depositing an amorphous tungsten trioxide film on the aluminum oxide insulating film obtained in the step 2 by vacuum thermal evaporation to obtain an active layer. The thickness of the tungsten trioxide film is 100-400nm, preferably 300nm in the embodiment, 0.2g of tungsten trioxide nano powder is weighed as an evaporation source, the purity of the tungsten trioxide nano powder is higher than 99.9%, and the coating machine cavity is vacuumized until the pressure reaches 4 x 10-^-4And after Pa, adding a power supply of an evaporation boat for bearing the tungsten trioxide nano powder to 110A, wherein the temperature of the evaporation boat is about 1000 ℃, and the evaporation thickness is 300 nm.

And 4, depositing a source electrode and a drain electrode on the tungsten trioxide layer prepared in the step 3 through thermal evaporation, wherein the source electrode and the drain electrode are metal electrodes, and specifically can be at least one of Au, Ag and Cu. In the embodiment, 0.2g of Au is taken as an evaporation source, and the chamber of the film plating machine is vacuumized until the pressure reaches 4 multiplied by 10^-4After Pa, the evaporation boat power was increased to 90A. The thickness of the evaporated electrode is 60 nm.

And 5, reversing the solid electrolyte on the basis of the step 4, and coating conductive silver paste on the back to serve as a gate electrode, wherein in other embodiments, the gate electrode can also be Au or Cu.

Therefore, the tungsten trioxide is applied to the transistor as the active layer, the preparation of the device adopts a vacuum coating method, the process is simple, the operation is easy to complete, and the method is compatible with the conventional integrated circuit process.

Fig. 2-3 are graphs showing the output characteristics and transfer characteristics of the pfet based on tungsten oxide according to the example of the present invention.

As can be seen from FIG. 2, when the gate voltage V is applied_GWhen the voltage is larger than the turn-on voltage (close to 0V), the drain current I_sdHardly following the drain voltage V_sdIs increased by an increase in; when V is_GLess than the turn-on voltage, I_sdWith V_sdIs increased, and V_GWhen increasing in the negative direction, the same V_sdCorresponding to I_sdIt will also increase.

As can be seen from FIG. 3, the turn-on voltage of this embodiment is about 0.6V, and the device mobility can be calculated to be 7.6 × 10^- ²cm²/Vs。

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. A preparation method of a P-type field effect transistor based on tungsten oxide is characterized by comprising the following steps:

providing a solid electrolyte sheet as a substrate;

evaporating a source electrode and a drain electrode on the active layer;

depositing a gate electrode on the other surface of the substrate;

the width of the channel region is less than 100 μm;

the solid electrolyte sheet is used as a gate medium, and due to the extremely strong long-range ion-electron coupling characteristic of the electrolyte, when the gate electrode is far away from a channel region, the conductivity of the channel can be still extremely regulated and controlled.

2. The production method according to claim 1, characterized in that: the solid electrolyte sheet is a lithium ion ceramic.

3. The production method according to claim 1 or 2, characterized in that: the thickness of the insulating film is 10-50 nm, and the insulating film is Al₂O₃、SiO₂、Si₃N₄、HfO₂Or ZrO₂。

4. The production method according to claim 3, characterized in that: the tungsten trioxide active layer is an amorphous film, and the thickness of the tungsten trioxide active layer is 100-400 nm.

5. The production method according to claim 4, characterized in that: the thickness of the tungsten trioxide active layer is 300 nm.

6. The production method according to claim 3, characterized in that: the source electrode, the drain electrode and the gate electrode are at least one of Au, Ag and Cu.

7. The method of claim 4, wherein the depositing of the tungsten trioxide active layer comprises adjusting a pressure of a vacuum evaporation chamber to 4 x 10 using tungsten trioxide nanopowder with a purity higher than 99.9% as a raw material^-4～5×10^-4Pa, the temperature of the evaporation boat is about 1000 ℃, and tungsten trioxide is evaporated in vacuum.

8. A tungsten oxide based P-type field effect transistor, comprising: the device comprises an insulating film positioned on one surface of a solid electrolyte sheet, wherein a strip-shaped channel region, a tungsten trioxide active layer positioned on the insulating film and the channel region, a source drain electrode positioned on the tungsten trioxide active layer and a gate electrode positioned on the other surface of the solid electrolyte sheet are arranged in the insulating film;

the width of the channel region is less than 100 μm;

9. The FET of claim 8, wherein the tungsten trioxide active layer is an amorphous thin film, the thickness of the tungsten trioxide active layer is 100-400nm, the thickness of the insulating thin film is 10-50 nm, and the material of the insulating thin film is Al₂O₃、SiO₂、Si₃N₄、HfO₂Or ZrO₂。