CN115354287A

CN115354287A - Method for preparing film on substrate by magnetron sputtering

Info

Publication number: CN115354287A
Application number: CN202210972675.7A
Authority: CN
Inventors: 孙钰婷; 曾昱嘉; 唐伟; 梁华伟
Original assignee: Shenzhen University
Current assignee: Shenzhen University
Priority date: 2022-08-15
Filing date: 2022-08-15
Publication date: 2022-11-18
Anticipated expiration: 2042-08-15
Also published as: CN115354287B

Abstract

The invention provides a method for preparing a film on a substrate by magnetron sputtering, which utilizes the magnetron sputtering technology, sets a certain angle between the center of a sputtering source and the center of the substrate, and then forms a double-layer film by in-situ oxidation on the surface of the sputtered film formed on the surface of the substrate by pure oxygen. The invention can obtain a high-performance double-layer magnetic film structure on a flexible PEN substrate by magnetron sputtering technology and setting the center of a sputtering source and the center of the substrate to form a certain angle, most preferably a 30-degree angle, wherein the target is cobalt, and the exchange bias value of the double-layer magnetic film structure is 6217oe which is obtained by preparation on the flexible substrate in the same system experiment at present. The film has good retentivity on the flexible substrate, the exchange bias value is not greatly different under the same condition after being bent for 500 times, and the value before and after being bent is kept within 10 percent. The method is equally applicable to rigid substrates.

Description

Method for preparing film on substrate by magnetron sputtering

Technical Field

The invention relates to the technical field of magnetic superconducting material preparation, in particular to a method for preparing a film on a substrate by utilizing magnetron sputtering.

Background

The exchange bias effect is an interface effect that occurs when a ferromagnetic layer in a magnetic material is in contact with an antiferromagnetic layer. The effect is an important performance of the magnetic spin material, has great prospect in application, and is one of important performance indexes of future magnetic random storage, fast storage and magnetic superconducting devices. Since there are many known systems that can be used to generate the exchange bias, and there are many ferromagnetic and antiferromagnetic materials, there are also many studies and experimental methods for generating the exchange bias. However, from the current relevant research reports, the exchange bias values of various systems are not greatly broken through, and the exchange bias experimental reports with a lot of better data have high requirements on experimental equipment, too high research cost and relatively harsh reaction conditions, so that the method has no practical application prospect for the time being.

The magnetron sputtering method for preparing the film is a common method, has the advantages of high deposition speed and low temperature rise of a base material, and can realize sputtering as long as most materials can be prepared into a target material. However, because magnetron sputtering atoms have uncontrollable properties, a dense and uniform layered thin film cannot be formed in a hundred percent. Most of the films do not have good performance in terms of the current magnetron sputtering technology.

Under the circumstances that flexible materials are rapidly developed, the requirements of people on technical and scientific products also include portability and portability of the products, which provides a clear direction for related research, namely changing the prior rigid silicon substrate and replacing a relatively lightweight flexible substrate with a flexible substrate with good flexibility, wherein the flexible substrate which is used at present is PI, flexible mica, PVDF, PEN and the like. There have been many studies on the preparation of ferromagnetic layers, antiferromagnetic layer films or the exchange bias on flexible substrates by various methods, and the exchange bias value in these studies is mostly around 200 to 600oe, for example: the exchange bias value of the multilayer material structure prepared on the PI material is 200oe; LSMO/NiO and Fe prepared on flexible mica material ₃ O ₄ The exchange bias achieved for the/BFO two materials is also at 200oe and 600oe; the exchange bias on PDMS was 135oe, although flexible, but the effect was less than ideal. Therefore, the film with excellent comprehensive performance and exchange bias effect is prepared on the flexible substrateExtremely high demand.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a method for preparing a film on a substrate by utilizing magnetron sputtering, and the method can prepare the high-performance film with exchange bias effect on a flexible or rigid substrate and still keep the original performance after bending without reduction. The technical scheme of the invention is as follows:

the method for preparing the film on the substrate by utilizing magnetron sputtering utilizes the magnetron sputtering technology, a certain angle is formed between the center of a sputtering source and the center of the substrate, and then pure oxygen is utilized to carry out in-situ oxidation on the surface of the sputtered film formed on the surface of the substrate to form a double-layer film.

Further, the certain angle is 20-30 degrees.

Preferably, the certain angle is 30 °.

Further, the method comprises the steps of:

1) Fixing a substrate on a sample table of a magnetron sputtering cavity, and arranging the center of a sputtering source to form a certain angle with the center of the substrate;

2) Reducing the vacuum degree of the magnetron sputtering cavity to 1 × 10 ^-3 ～1×10 ^-4 Pa, then introducing inert gas, controlling the flow of the inert gas to be 30-50 atm, and adjusting the pressure of the magnetron sputtering cavity to be 1.5 multiplied by 10 ^-1 ～2.0×10 ^-1 Pa；

3) Starting a sputtering source, controlling the sputtering power to be 80-100W and the sputtering time to be 20-120 s, and keeping a sample table fixed so as to form a sputtering film on the surface of the substrate;

4) After sputtering, oxygen is introduced, the oxygen flow is controlled to be 40-60 atm, and the pressure of the magnetron sputtering cavity is controlled to be 1.8 multiplied by 10 ^-1 ～3.0×10 ^-1 Pa, and exposing the sputtering film to an oxygen atmosphere for 3-10 min to further form an oxide film on the surface of the sputtering film.

Further, the substrate is fixed on a magnetron sputtering sample table through a polyimide PI adhesive tape.

Further, the substrate is a flexible substrate or a rigid substrate.

Further, the flexible substrate is selected from PEN, PI, PVDF or flexible mica.

Further, the rigid substrate is selected from silicon, glass or silicon dioxide.

Preferably, the vacuum degree of the magnetron sputtering cavity in the step 2) is reduced to 1 × 10 ^-4 Pa, introducing inert gas at 50atm, and regulating the pressure of the magnetron sputtering chamber to 1.5 × 10 ^-1 Pa。

Preferably, the sputtering power in the step 3) is 80W, and the sputtering time is 50s.

Preferably, the oxygen flow in the step 4) is 60atm, and the pressure of the magnetron sputtering chamber is controlled to be 1.8 × 10 ^-1 The sputtered film was exposed to an oxygen atmosphere for 3min.

The invention can obtain a high-performance double-layer magnetic film structure on a flexible PEN substrate by magnetron sputtering technology and adjusting the center of a sputtering source to form a certain angle with the center of the flexible substrate, most preferably an angle of 30 degrees, wherein the target is cobalt, and the exchange bias value of the double-layer magnetic film structure is 6217oe which is prepared on the flexible substrate in the same system experiment at present. The film has good retentivity on the flexible substrate, the exchange bias value is not greatly different under the same condition after being bent for 500 times, and the value before and after being bent is kept within 10 percent. The method is equally applicable to rigid substrates.

Drawings

FIG. 1 is a diagram illustrating an angle control of a center of a sputtering source and a center of a flexible substrate in a method according to an embodiment of the invention.

FIG. 2 is a picture taken by a scanning electron microscope of the surface topography of a sample of example 1 of the present invention

FIG. 3 is a hysteresis loop of a cobalt/cobalt oxide bilayer film structure obtained in example 1 of the present invention.

FIG. 4 is a hysteresis loop of a cobalt/cobalt oxide bilayer film structure obtained in example 1 of the present invention compared before and after bending.

FIG. 5 is a data image obtained by theoretical model simulation of embodiment 1 of the present invention, wherein (a) is a diagram of a theoretical calculation model; graph (b) is simulated data.

FIG. 6 shows the element distribution and content in the vertical section of the sample obtained in example 3 of the present invention, wherein 1) is a Co distribution, 2) is a Si distribution, and 3) is an O distribution.

FIG. 7 is a comparison of data from example 1 and example 3 at the same temperature and same angle.

Detailed Description

In the description of the present invention, it is to be noted that those whose specific conditions are not specified in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturers. The reagents or instruments used are conventional products which are not indicated by manufacturers and are commercially available.

The present invention will be described in further detail with reference to the drawings and detailed description, so as to enable those skilled in the art to more fully, accurately and deeply understand the concept and technical solution of the present invention, and the scope of the present invention includes but is not limited to the following examples, and any modifications made to the details and form of the technical solution of the present invention can be made within the scope of the present invention without departing from the spirit and scope of the present application.

Example 1

The embodiment provides a method for preparing a film on a flexible substrate by magnetron sputtering, wherein a PEN film (polyethylene naphthalate) is used as a substrate material, and the material has the advantages of good heat resistance, high light transmittance, good flexibility and the like, is smooth and flat in surface, and is a good flexible substrate material. The method comprises the following specific steps:

(1) Fixing the flexible substrate on a sample table of a magnetron sputtering chamber, adjusting the sputtering source to a certain degree to enable the center of the sputtering source and the center of the flexible substrate to form a 30-degree angle, and placing a cobalt target with the purity of 99.999% on a target position at the center of the sputtering source, as shown in fig. 1.

(2) Firstly, a mechanical pump is used for vacuumizing, after the vacuum degree is reduced to below 10Pa, a gate valve is opened, a molecular pump is started, the molecular pump is used for vacuumizing for 40min, and the vacuum degree in the magnetron sputtering cavity is ensured to be 10 ^-4 Pa。

(3) Introducing argon gas into the cavity, controlling the flow at 50atm, and opening the flashboardValve for controlling air pressure in the chamber to 1.5 × 10 ^-1 Pa。

(4) And turning on a direct-current sputtering power supply in an argon atmosphere, keeping the sample table not to rotate during sputtering with the power of 80W and the sputtering time of 50s, so that the cobalt film sputtered in one direction is obtained.

(5) After sputtering is finished, the target material baffle is closed, the argon inlet is closed, the oxygen inlet valve is opened, the oxygen flow is adjusted to be 60atm, and the air pressure of the cavity is kept to be 1.8 multiplied by 10 ^-1 Pa。

(6) And opening the sample baffle, exposing the sample in pure oxygen atmosphere, and keeping for 3min to generate a layer of compact cobalt oxide on the surface, so as to obtain a cobalt/cobalt oxide double-layer film structure, wherein the surface appearance is shown in figure 2.

The sample of the double layer thin film-flexible substrate obtained in this example was taken out and the M-H curve of the material was measured using PPMS (comprehensive physical property measurement) to obtain a curve as shown in fig. 3, which indicates that after the Co/CoO system including a Ferromagnetic (FM)/Antiferromagnetic (AFM) interface was cooled from a temperature higher than the magnetic neel temperature of CoO to a low temperature in an external magnetic field, the hysteresis loop of the ferromagnetic layer would be deviated from the origin in the opposite direction of the magnetic field with an increase in the coercive force, the deviation being referred to as the exchange bias field. The exchange offset value can be calculated to be 6217oe according to the offset. In order to verify the stability of the material, the material was taken out, and the test was carried out under the same conditions after 500 times of bending, and the obtained curve is shown in fig. 4, and has no great difference, and the curve before and after bending is kept within 10%, which indicates that the sample has stronger stability.

In addition, in the experiment, a thin film is sputtered, and oxygen elements can be brought into the film by using pure oxygen for in-situ oxidation, because exchange bias is an interface effect, the contact area of two layered substances is increased equivalently, and a large exchange bias value is obtained, the specific calculation principle is that an atomic spin model constrained by the Landau-Li Fuxi Z-Gilbert-Brown equation is adopted for simulation, and the formula is as follows:

wherein m is _i Is the local magnetic moment at the ith site; gamma ray ₀ Is the gyromagnetic ratio, α is the gilbert damping factor, set here to 0.1; b is _i Is a magnetic field; t is time; eff denotes the effective magnetic field strength; magnetic rotation ratio gamma ₀ ＝1.76×10 ^-4 (fs ^-1 T ^-1 )。

The related model diagram is shown in fig. 4. Also, the oxygen distribution map obtained by EDS mapping was confirmed (3 in FIG. 6). It is shown that in this way there is no longer a simple bilayer membrane contact, which produces better results.

Example 2

The present embodiment provides a method for preparing a thin film on a flexible substrate by magnetron sputtering, which is different from embodiment 1 in that: the sputter source center was 20 ° from the center of the flexible substrate, and the exchange bias value of the resulting bilayer film was 2500oe.

Example 3

This example provides a method for producing thin films by magnetron sputtering on rigid substrates of silicon, otherwise as in example 1, we obtained almost the same values of exchange bias in comparative experiments on rigid substrates, the difference being less than five percent as shown in figure 6 above. We can confirm that there is no large difference in the properties of the samples prepared using this experimental approach on the flexible substrate and the rigid substrate.

Comparative example 1

The present comparative example provides a method for preparing a thin film on a flexible substrate using magnetron sputtering, which is different from example 1 in that: the center of the sputtering source is 5 degrees with the center of the flexible substrate, and the exchange bias value of the finally obtained double-layer film is 2000oe.

In the exploration of the exchange bias of the flexible substrate, a plurality of people have already made a plurality of previous researches, and the obtained exchange bias value is 200oe in a multilayer material structure prepared on a PI material; the exchange bias obtained for the two materials prepared on the flexible mica material was also 200oe and 600oe; the exchange bias on PDMS is 135oe, the above is different from the flexible substrate material, the bias generating ferromagnetic layer and antiferromagnetic material are different, and there is no flexibility research of similar materials at present, which is the first example of the present invention.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The method for preparing the film on the substrate by utilizing magnetron sputtering is characterized by comprising the following steps: the method utilizes a magnetron sputtering technology, a certain angle is formed between the center of a sputtering source and the center of a substrate, and then pure oxygen is utilized to carry out in-situ oxidation on the surface of a sputtered film formed on the surface of the substrate to form a double-layer film.

2. The method for preparing a thin film on a substrate by magnetron sputtering according to claim 1, wherein: the certain angle is 20-30 degrees.

3. The method for preparing a thin film on a substrate by magnetron sputtering according to claim 1 or 2, wherein: the certain angle is 30 °.

4. The method for preparing a thin film on a substrate by magnetron sputtering according to claim 3, wherein: the method comprises the following steps:

1) Fixing the substrate on a sample stage of a magnetron sputtering chamber, and arranging the center of a sputtering source to form a certain angle with the center of the substrate;

2) Reducing the vacuum degree of the magnetron sputtering cavity to 1 multiplied by 10 ^-3 ～1×10 ^-4 Pa, then introducing inert gas, controlling the flow of the inert gas to be 30-50 atm, and adjusting the pressure of the magnetron sputtering cavity to be 1.5 multiplied by 10 ^-1 ～2.0×10 ^-1 Pa；

3) Starting a sputtering source, controlling the sputtering power to be 80-100W, controlling the sputtering time to be 20-120 s, and keeping a sample table fixed to form a sputtering film on the surface of the substrate;

4) After sputtering, oxygen is introduced, the flow of oxygen is controlled to be 40-60 atm, and the air pressure of the magnetron sputtering cavity is controlled to be 1.8 multiplied by 10 ^-1 ～3.0×10 ^-1 Pa, and exposing the sputtering film to an oxygen atmosphere for 3-10 min to further form an oxide film on the surface of the sputtering film.

5. The method for preparing a thin film on a substrate by magnetron sputtering according to claim 4, wherein: the substrate is fixed on a magnetron sputtering sample table through a polyimide PI adhesive tape.

6. The method for preparing a thin film on a substrate by magnetron sputtering according to claim 5, wherein: the substrate is a flexible substrate or a rigid substrate.

7. The method for preparing a thin film on a substrate by magnetron sputtering according to claim 6, wherein: the flexible substrate is selected from PEN, PI, PVDF or flexible mica.

8. The method for preparing a thin film on a substrate by magnetron sputtering according to claim 6, wherein: the rigid substrate is selected from silicon, glass or silicon dioxide.

9. The method for preparing a thin film on a substrate by magnetron sputtering according to claim 4, wherein: the vacuum degree of the magnetron sputtering cavity in the step 2) is reduced to 1 multiplied by 10 ^-4 Pa, introducing inert gas with a flow rate of 50atm, and regulating the pressure of the magnetron sputtering chamber to 1.5 multiplied by 10 ^-1 Pa。

10. The method for preparing a thin film on a substrate by magnetron sputtering according to claim 4, wherein: the sputtering power in the step 3) is 80W, and the sputtering time is 50s.