CN110190134B - Amorphous oxide thin film device and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of electronic equipment, and particularly relates to an amorphous oxide thin film device and a preparation method thereof. The present invention provides an amorphous oxide thin film device, which uses a glass substrate as a base layer, and physically vapor-deposits an Hf target on the glass substrate to obtain an HfO ₂ thin film to form a product 1. Annealed under the condition of ℃ to form product 2, and electrodes are plated on the surface of the HfO ₂ film of the product 2 and the glass substrate without the HfO ₂ film deposited. The invention provides an oxide thin film device with diode effect with good stability; the invention also discloses a preparation method of an amorphous oxide thin film device with a simple preparation process.

Description

Amorphous oxide thin film device and preparation method thereof

technical field

The invention belongs to the technical field of electronic devices, and in particular relates to an amorphous oxide thin film device and a preparation method thereof.

Background technique

Diode is one of the most commonly used electronic components, diode (English: Diode), its biggest characteristic is that it has unidirectional conduction, that is, current can only flow in one direction of the diode, and only allows current to flow in one direction. Usage is the function of applying its rectification. The varicap diode (Varicap Diode) is used as an electronic adjustable capacitor. The function of the diode includes a rectifier circuit, a detection circuit, a voltage regulator circuit, and various modulation circuits, which are mainly composed of diodes.

In recent years, with the rapid development of thin film preparation technology, functional thin film devices have received more and more attention in the field of microelectronics. The system composed of metal (M)-insulator (I)-semiconductor (S) is called MIS structure , The device formed with this structure is called MIS device (MIS diode). At present, the research focus of MIS device is oxide thin film device. The oxide thin film device has a diode effect, but the stability of the diode effect of the existing oxide thin film device is poor, the preparation process is complicated, and large-scale industrial production is difficult.

SUMMARY OF THE INVENTION

In view of this, the first object of the present invention is to provide a stable amorphous oxide thin film device with diode effect; the second object of the present invention is to disclose an amorphous oxide thin film with a simple preparation process Device preparation method.

The invention provides an amorphous oxide thin film device, which uses a glass substrate as a base layer, and physically vapor-deposits a Hf target on the glass substrate to obtain an HfO ₂ thin film to form a product 1. Annealed under the condition of ℃ to form product 2, and electrodes are plated on the surface of the HfO ₂ thin film of the product 2 and the glass substrate without HfO ₂ thin film deposited.

It should be noted that the electrode on the surface of the HfO ₂ thin film is the top electrode, and the electrode on which the HfO ₂ thin film is not deposited is the bottom electrode.

Preferably, the thickness of the HfO ₂ thin film is 100-200 nm.

Preferably, the annealing time is 5-10 min.

Preferably, the physical vapor deposition is selected from vacuum evaporation, sputtering coating, arc plasma coating, ion coating or molecular beam epitaxy.

Preferably, the glass substrate is selected from one of FTO conductive glass, Pt substrate, strontium ruthenate substrate or mica substrate.

Preferably, the electrodes are point electrodes.

Preferably, the point electrode is selected from one or more of Au, Pt, Al, Ag, Ti, TiN and W.

The present invention also provides a preparation method of the oxide thin film device, comprising the following steps:

Step 1. Using the Hf target material as the deposition target material and the glass substrate as the base layer, obtain a HfO ₂ thin film by physical vapor deposition on the surface of the glass substrate to form Product 1;

Step 2, annealing the product 1 at 500-600° C. to obtain the product 2;

Step 3. Electrodes are plated on both sides of the product 2.

Preferably, the annealing time is 5-10 min.

Preferably, it also includes step 0, using absolute ethanol to clean the surface of the Hf target;

The surface of the silicon wafer was cleaned with HF, and then cleaned with absolute ethanol.

The present invention also provides a specific preparation method of the amorphous oxide thin film device, comprising the following steps:

Step 1. Take the Hf target as the deposition target, the glass substrate as the base layer, the vacuum environment of 5.0×10 ^-3 Pa, pass in the protective gas, control the current of magnetron sputtering to be 250-400mA, and the voltage to be 500- 1000V, the time of magnetron sputtering is 25-40min, and product 1 is obtained;

Step 2, annealing the product 1 at 500-600° C. for 5-10 min to obtain the product 2;

Step 3. Electrodes are plated on both sides of the product 2.

It should be noted that the electrode on the surface of the HfO ₂ thin film of the product 2 is the top electrode, and the electrode of the product 2 on which the HfO ₂ thin film is not deposited is the bottom electrode.

Preferably, the protective gas includes argon gas and oxygen gas, and the flow ratio of the argon gas and the oxygen gas is 40:(5-15). More preferably, the flow ratio of the argon gas and the oxygen gas is 40:10. Wherein, the flow rate of the oxygen can not be too little or too much, too little will lead to insufficient oxidation, too much will lead to failure to ignite.

Preferably, the preparation method further includes step 0, using absolute ethanol to clean the surface of the Hf target;

The surface of the silicon wafer was cleaned with HF, and then cleaned with absolute ethanol.

Specifically, the preparation method of the amorphous oxide thin film device of the present invention includes the following steps:

1) Prepare the Hf target and the cut glass substrate; use anhydrous ethanol to wipe the Hf target to make its surface clean without any contamination, and use hydrofluoric acid (HF) to scrub the front of the cut glass substrate for the glass substrate (purpose to wipe off the SiO ₂ on the surface of the glass substrate), then use absolute ethanol to clean the surface of the glass substrate, after cleaning, install the target and silicon wafer according to the specifications of the magnetron sputtering instrument;

2) Turn on the circulating water system of the magnetron sputtering apparatus, turn on the main switch, turn on the mechanical pump to evacuate to make the vacuum gauge of the magnetron sputtering apparatus reach 5Pa, then turn on the solenoid valve and the molecular pump to evacuate to 5.0×10 ^-3 Pa ;

3) Open the gas valve, pass argon (Ar) and oxygen (O ₂ ), open the flow meter, and adjust the flow ratio of Ar to O ₂ to 40:(5-15) (the ratio of oxygen should not be too small or too much , too little will lead to insufficient oxidation, too much will lead to failure to ignite), and adjust the plate valve to make the vacuum gauge show a vacuum of 5Pa; after the argon-oxygen ratio and pressure are stable, turn on the radio frequency (RF) power switch, ignite. Preheat the filament for 3-5 minutes; adjust the flow ratio of Ar and O ₂ to be strictly controlled, the purpose is to fully react with O ₂ to form HfO ₂ in the process of metal sputtering;

4) Turn on the radio frequency power supply to make the Hf target glow, and adjust the power: the current is 250-400mA, the voltage is 500-1000V, and the glowing color of the Hf target is dark golden yellow;

5) After sputtering for 25-40 minutes under the power of the step 4) (the power is related to the sputtering time, the smaller the power, the longer the sputtering time should be, and the higher the power, the better the sputtering time should be appropriately shortened), turn off RF power supply, turn off the instrument according to the procedure and take out the produced product 1;

6) taking out the product 1 of step 5), and annealing at 500-600° C. for 5-10 minutes to obtain sample 2, wherein the annealing atmosphere is oxygen (annealing in an oxygen atmosphere makes the film fully oxidized);

7) Cover the sample 2 with a layer of mask (there are many holes on the mask, so that the plated electrodes are point-by-point electrodes for easy measurement) and plated with point electrodes, which can be Au, Ti, Al, Ag One or more of , W and Pt.

The object of the present invention is to provide an amorphous oxide thin film device. The amorphous oxide thin film device of the present invention has a good diode effect. The amorphous oxide thin film device of the present invention is prepared by physical deposition technology, and the amorphous oxide thin film device obtained is obtained. The amorphous oxide of the present invention has the advantages of high mobility, low preparation temperature and high uniformity. Through the tested XRD pattern, XPS pattern and I-V (Current-Voltage) results, it is found that its It has stable diode effect and remarkable characteristics; in addition, the preparation process of the amorphous oxide thin film device of the present invention is simple and convenient, and the physical deposition technology has many advantages, such as easy preparation method, simple equipment, uniform preparation film surface, and controllable thickness, etc. It is convenient for large-scale industrial production.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that are required in the description of the embodiments or the prior art.

₁ is a structural diagram of an amorphous oxide thin film device provided by the present invention, wherein, substrate is an FTO substrate, films are HfO films, and electrodes are electrodes;

2 is an I-V diagram of the amorphous oxide thin film device prepared in Example 1 of the present invention on an FTO substrate, and the annealing temperature is 550°C;

FIG. 3 is an I-V diagram of the amorphous oxide thin film device prepared in Example 1 of the present invention on an FTO substrate, and the annealing temperature is 550° C., and the amorphous oxide thin film device is cycled 500 times;

Fig. 4 is the XRD pattern of the device prepared by the comparative example of the present invention;

Fig. 5 is the XPS spectrum of the device prepared by the comparative example of the present invention;

Fig. 6 is the I-V curve of the device prepared by the comparative example of the present invention.

Detailed ways

The invention provides an amorphous oxide thin film device and a preparation method thereof, which are used to solve the technical defect of low diode effect stability in the existing oxide thin film device.

The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Among them, the raw materials used in the following examples are all commercially available or homemade, the purity of the used target material is 99.99%, and the purity of the used gold target is 99.99%.

Example 1

The invention provides an amorphous oxide thin film device. The HfO2 thin film device is prepared by a magnetron sputtering coating method: Hf target and FTO conductive glass are prepared, cleaned and installed according to the requirements of the device. Use the procedure to evacuate to 5×10 ⁻³ Pa and then pass through argon and oxygen, and control Ar:O2=40:10. After sputtering for 30 minutes after ignition, the device was turned off to take out the sample, and the taken out sample was placed in a rapid annealing furnace, and annealed in an oxygen atmosphere for 10 minutes, and the annealing temperature was 550°C. The annealed sample was covered with a mask plate and coated with a layer of gold dot electrodes, and the preparation was completed. Test the IV, and the performance of the IV that is cycled 500 times, the specific steps are as follows:

1) Prepare Hf target and cut FTO conductive glass.

2) Wipe the Hf target with absolute ethanol to make the surface clean without any contamination. Use hydrofluoric acid (HF) to scrub the front side of the cut silicon wafer (the purpose is to wipe off the SiO ₂ on the surface of the silicon wafer), and then use Wash the wafers with water ethanol. After cleaning, install the Hf target and silicon wafer according to the specifications of the magnetron sputterer.

3) Turn on the circulating water system of the magnetron sputtering apparatus, turn on the main switch, and turn on the mechanical pump to pump vacuum so that the vacuum gauge of the magnetron sputtering apparatus reaches 5Pa. Then open the solenoid valve and the molecular pump to evacuate to 5.0×10 ^-3 Pa.

4) Open the gas valve, pass argon (Ar) and oxygen (O ₂ ), open the flowmeter, adjust Ar:O2≈40:10, and adjust the plate valve so that the vacuum gauge shows a vacuum of 5Pa.

5) Turn on the radio frequency power supply to make the target glow, and adjust the power: the current is 350mA, the voltage is 1000V, and the glow color is dark golden yellow.

6) After sputtering under the power of step 5) for 30 minutes, turn off the radio frequency power supply, turn off the instrument according to the program, and then take out the produced product 1.

7) The product 1 taken out in the step 6) is annealed at 550° C. for 15 minutes to obtain the product 2 whose annealing atmosphere is oxygen.

8) For the product 2 that has been annealed in the step 7), cover the product 2 with a layer of mask (there are many holes on the mask, so that the plated electrodes are little by little electrodes for easy measurement) and plated on A gold electrode was obtained to obtain an oxide thin film device, and its performance was tested and found to have a good photodiode effect. The results are shown in Figure 2-3.

FIG. 1 is a structural diagram of an amorphous oxide thin film device provided by the present invention, wherein the substrate is an FTO substrate, the films are HfO ₂ films, and the electrodes are electrodes. The amorphous oxide thin film device provided by the present invention includes a base layer, a HfO ₂ thin film layer and an electrode layer. The device of the present invention is very easy to prepare, and only needs to deposit a layer of HfO ₂ thin film on the cleaned substrate by physical vapor phase, which is favorable for large-scale popularization and production.

Compared with the existing amorphous oxide thin film devices with the same unit area and the diode effect produced by the preparation method of the present application, the preparation efficiency of the preparation method of the present application is higher than that of the existing preparation methods. .

FIG. 2 is the IV spectrum of the HfO ₂ oxide thin film device obtained by annealing FTO as the substrate in an oxygen atmosphere at 550° C. in Example 1 of the present application. As shown, the test goes from 0 to 3V to -3V, and then takes the data for one measurement from -3V to 3V. The figure shows the forward conduction, and the reverse will not be instantaneously turned on until the conduction voltage is -2V to generate current, and its data is stable and reliable.

FIG. 3 is the IV spectrum of the HfO ₂ oxide thin film device obtained in Example 1 of the present application using FTO as the substrate in an oxygen atmosphere at 550° C. for 500 cycles of annealing tests. As shown in the figure, the test is one cycle from -3V to 3V, and 500 cycles are measured, and then the first (1st), tenth (10th), 100th (100th) and 500th times are taken. (500th) data. It can be seen from the figure that the diode performance of the amorphous oxide thin film diode device is very stable after 500 cycles.

Comparative Example 1

The present invention provides a comparative example, the specific preparation method is as described in Example 1, the difference is that this comparative example uses magnetron sputtering to coat Pt, and its annealing temperature is 700°C, to obtain the product of Comparative Example 1, Comparative Example 1 was analyzed by XRD, XPS and IV, and the results are shown in Figures 4-6. Fig. 4 is the XRD pattern of the device prepared by the comparative example of the present invention; Fig. 5 is the XPS pattern of the device prepared by the comparative example of the present invention; Fig. 6 is the IV curve diagram of the device prepared by the comparative example of the present invention. As shown in Fig. 4-6, the Hf target was magnetron sputtered _on the Pt substrate, and the annealing temperature of the oxygen atmosphere was 700 ℃. When the temperature is 700 ° C, it has been crystallized. From the XPS spectrum of the product of Comparative Example 1, the composition of the product of Comparative Example 1 is HfO ₂ , and from the IV spectrum of the product of Comparative Example 1, it can be known that the product of Comparative Example 1 did not form a diode.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (5)

1. Amorphous HfO₂The thin film device is characterized in that a glass substrate is used as a substrate layer, and the physical vapor deposition of Hf target material on the glass substrate is used for obtaining HfO₂A film is formed to form a product 1, the product 1 is annealed at the temperature of 500-600 ℃ to form a product 2, and HfO of the product 2₂Surface of thin film and no deposition of HfO₂Plating electrodes on the glass substrate of the film;

the glass substrate is FTO conductive glass;

the HfO₂The thickness of the film is 100-200 nm;

the annealing time is 5-10 min;

the electrode is a point electrode.

2. Amorphous according to claim 1HfO₂A thin film device, wherein the physical vapor deposition is one method selected from the group consisting of vacuum evaporation, sputter coating, arc plasma coating, ion coating, and molecular beam epitaxy.

3. Amorphous HfO according to claim 1₂The thin film device is characterized in that the point electrode is one or more selected from Au, Pt, Al, Ag, Ti, TiN and W.

4. Amorphous HfO according to any of claims 1 to 3₂The preparation method of the thin film device is characterized by comprising the following steps of:

step 1, taking a Hf target material as a deposition target material and a glass substrate as a basal layer, and carrying out physical vapor deposition on the surface of the glass substrate to obtain HfO₂Film, forming product 1; the glass substrate is FTO conductive glass; the HfO₂The thickness of the film is 100-200 nm;

step 2, annealing the product 1 at the temperature of 500-600 ℃ to obtain a product 2; the annealing time is 5-10 min;

step 3, HfO of the product 2₂Surface of thin film and no deposition of HfO₂Plating electrodes on the glass substrate of the film; the electrode is a point electrode.

5. The method according to claim 4, further comprising a step 0 of cleaning the surface of the Hf target material with absolute ethanol;

the surface of the silicon wafer was cleaned with HF and then with absolute ethanol.

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