CN110246656A - A kind of multi-layer-coupled patterned magnetic film and preparation and test method - Google Patents

Abstract

The invention discloses a multilayer coupled patterned magnetic film, a preparation method and a testing method. The film comprises: a substrate, a continuous film layer and a patterned film layer; the continuous film layer is grown on the substrate, and the continuous film layer The shape of the electrode is formed to provide the magnetic moment distribution out of the plane, and to provide the basis for testing the electrical properties of the multilayer coupling patterned magnetic film. The patterned film layer is formed on the continuous film layer, and the patterned film layer is a discontinuous structure. The patterned thin film layer is used to provide the magnetic moment distribution of the vortex state. The present invention combines the sputtering coating technology and the photolithography process to prepare a multi-layer coupling patterned magnetic film with a discontinuous structure, realizes the goal of using PPMS to test the resistance of the multi-layer coupling patterned magnetic film as a whole, and solves the magnetic problem of the discontinuous structure. Thin films need to use electrode probes to test individual units one by one. The test process is convenient and simple, and the time is very short, which greatly improves the work efficiency of the staff.

Description

A kind of multilayer coupled patterned magnetic thin film and its preparation and testing method

technical field

The invention relates to the field of materials, in particular to a multilayer coupled patterned magnetic thin film, a preparation method and a method for testing electrical properties.

Background technique

Skyrmions are helical chiral magnetic structures with quasi-particle properties. Skyrmions are expected to become highly Density, low energy consumption, non-volatile information storage and emerging information carriers for logic operations. The chiral magnetic structure of skyrmions is caused by the Dzyaloshinskii-Moriya (DM) interaction, such as a compound composed of a metal and a semiconductor with a chiral B20 structure, or a combination of a heavy metal layer and an ultra-thin ferromagnetic layer to form a multilayer film , different from the Heisenberg exchange interaction, the DM interaction tends to make the adjacent magnetic moments orthogonally arranged, thereby forming a chiral helical structure. DM interaction is a weak force, so in non-centrosymmetric materials, skyrmion crystals can only exist in a narrow temperature range and in the region of an applied magnetic field, and the skyrmion formed by the micro-nano structure is stable The property is better than that of bulk materials, and it can maintain the stability of the spin structure in a large temperature range. Its preparation method is also compatible with traditional semiconductor manufacturing technology, and it is easy to realize large-scale industrial preparation.

The magnetic and topological properties of skyrmions are inseparable. There is a topological Hall effect in skyrmions that originates from the divergent field of its magnetic structure. To solve the problem, the electrical performance test of patterned thin films with discontinuous structures cannot be achieved by traditional methods.

Contents of the invention

In view of the above problems, the present invention provides a multilayer coupling patterned magnetic film, a preparation method and a method for testing electrical properties, which solves the problem that the electrical property testing of patterned films with discontinuous structures cannot be realized by traditional methods.

An embodiment of the present invention provides a multilayer coupled patterned magnetic film, the film comprising: a substrate, a continuous film layer and a patterned film layer;

The continuous thin film layer is grown on the substrate, and the continuous thin film layer forms an electrode shape for providing out-of-plane magnetic moment distribution and providing a basis for testing the electrical properties of the multilayer coupled patterned magnetic thin film, The substrate is used to provide support for the multilayer coupling patterned magnetic film and epitaxial growth of the continuous film layer;

The patterned thin film layer is formed on the continuous thin film layer, the patterned thin film layer has a discontinuous structure, and the patterned thin film layer is used to provide a magnetic moment distribution in a vortex state.

Optionally, the continuous thin film layer is grown on the substrate by high temperature assisted growth or epitaxial growth.

Optionally, the patterned thin film layer is a patterned disk array structure.

Optionally, the continuous film layer is prepared in the shape of a Hall Bar.

Optionally, the substrate is made of MgO.

Optionally, the continuous film layer is made of FePt.

Optionally, the patterned thin film layer is made of FeNi.

Optionally, when the applied magnetic field is perpendicular to the multilayer coupling patterned magnetic film, the resistance of the multilayer coupling patterned magnetic film changes with the change of the applied magnetic field, and is consistent with the multilayer comprising a continuous structure The resistance of the coupled patterned magnetic films is the same.

Optionally, the continuous thin film layer is grown on the substrate by high temperature assisted growth or epitaxial growth.

Optionally, the patterned thin film layer is a patterned disk array structure.

Optionally, the continuous film layer is prepared in the shape of a Hall Bar.

The embodiment of the present invention also provides a method for preparing a multilayer coupled patterned magnetic film, the method comprising:

Using substrate heating method to epitaxially grow FePt film on MgO, and co-sputtering Fe target and Pt target to prepare adjustable FePt film to obtain continuous film layer;

For the prepared adjustable FePt thin film, an adjustable FeNi thin film is prepared by sputtering a FeNi target, that is, a patterned thin film layer is obtained; wherein, the substrate, the continuous thin film layer and the patterned The film layer is composed of any one of the above-mentioned multilayer coupled patterned magnetic films;

Adjustable FePt films are prepared by co-sputtering of Fe targets and Pt targets, including:

Under the condition that the background vacuum is less than 4.5×10 ^-5 Pa, the sputtering pressure is adjusted to be 0.3~0.5Pa, the DC sputtering power of the Fe target is 8~20w, and the RF sputtering power of the Pt target is 10~35w , through Fe target and Pt target co-sputtering, alternate deposition to obtain FePt film;

Among them, FeNi patterned thin film layers are prepared by sputtering FeNi targets, including:

Under the condition that the background vacuum is less than 4.5×10 ^-4 Pa, the sputtering pressure is adjusted to be 0.2~0.4Pa, and the DC sputtering power of the FeNi target is 40~80w. FeNi is obtained by sputtering the FeNi target. film.

Optionally, the thickness of the FePt thin film layer is 10-30 nm, and the thickness of the FeNi thin film layer is 20-600 nm.

An embodiment of the present invention also provides a method for testing the electrical properties of a multilayer coupling patterned magnetic film. The comprehensive physical property measurement system applies a magnetic field in a direction perpendicular to any of the above multilayer coupling patterned magnetic films to obtain the obtained The resistance of the multilayer coupled patterned magnetic thin film changes with the change of the applied magnetic field, and is the same as the resistance of the multilayer coupled patterned magnetic thin film comprising a continuous structure.

The invention provides a multilayer coupled patterned magnetic film, in which continuous film layers are grown on a substrate, and the continuous film layers form an electrode shape for providing out-of-plane magnetic moment distribution and providing a test multilayer coupled patterned magnetic film The basis of the electrical properties of the invention, the patterned thin film layer is formed on the continuous thin film layer, the patterned thin film layer has a discontinuous structure, and the patterned thin film layer is used to provide the magnetic moment distribution of the vortex state. The coupling of the continuous film layer and the patterned film layer can form a skyrmion structure, which has various characteristics of the skyrmion. At the same time, the electrode shape formed by the continuous film layer provides a basis for testing the electrical properties of the multilayer coupled patterned magnetic film, making The multi-layer coupled patterned magnetic film can realize the integrity test of electrical properties without using electrode probes to test individual units one by one. The whole test process is convenient and simple, and the time is very short, which greatly improves the work efficiency of the staff.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiment. The drawings are only for the purpose of illustrating a preferred embodiment and are not to be considered as limiting the invention. Also throughout the drawings, the same reference numerals are used to designate the same parts. In the attached picture:

Fig. 1 is the schematic diagram of the magnetic thin film of a discontinuous structure at present;

2 is a schematic diagram of a multilayer coupled patterned magnetic film according to an embodiment of the present invention;

3 is a schematic diagram of a four-layer structure of a multilayer coupled patterned magnetic thin film according to an embodiment of the present invention;

Fig. 4 is the schematic diagram of FePt thin film layer and FeNi thin film layer in the embodiment of the present invention multilayer coupled patterned magnetic thin film;

Fig. 5 is a graph showing electrical performance testing of a multi-layer coupled patterned magnetic thin film according to an embodiment of the present invention.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, only a part of the embodiments of the present invention, not all the embodiments, and are not intended to limit the present invention.

The inventors have found that the current electrical performance tests for magnetic thin films with continuous structures basically use PPMS (Physical Property Measurement System), which can easily and conveniently test the resistance of magnetic thin films with continuous structures. The electrical performance test of the magnetic thin film with continuous structure can only use the electrode probe to test its electrical performance one by one. This method not only requires high test equipment, but also the test process is difficult, and the workload is heavy, which leads to the relevant staff. Work efficiency is low.

For example: the schematic diagram of the magnetic thin film of a discontinuous structure as shown in Figure 1, it is the magnetic thin film of the discontinuous structure of 40 nanometers (nm) thick, 70 nanometers long, assuming that needs to test its electric performance, then need to use The individual units of the electrode probes are tested one by one, and the electrical performance of unit 1 in Figure 1 is first tested to obtain its resistance. Because the magnetic film is a periodic structure, the properties of each unit are consistent, so the electrical performance test results of unit 2 in Figure 1 Same as Unit 1. Although the accuracy of the test results can be guaranteed by the above method, the process of completing the test is cumbersome and takes a long time, resulting in extremely low work efficiency of the staff.

Aiming at the above problems, the inventors, after painstaking research, combined a large number of calculations and actual measurements, and creatively combined sputtering coating technology and photolithography technology, prepared a discontinuous structure, multi-layer coupled patterned magnetic film, the magnetic film The resistance can be directly measured by PPMS, which greatly simplifies the electrical performance testing process of the magnetic thin film with discontinuous structure, reduces the workload, and greatly improves the working efficiency of the staff. The scheme of the present invention is explained and illustrated in detail below.

Figure 2 shows a schematic diagram of a multilayer coupled patterned magnetic film according to an embodiment of the present invention, the magnetic film includes: a substrate 10, a continuous thin film layer 20 and a patterned thin film layer 30; wherein the continuous thin film layer 20 grows On the substrate 10, the continuous thin film layer 20 forms an electrode shape, which is used to provide out-of-plane magnetic moment distribution, and provides the basis for testing the electrical properties of the multilayer coupling patterned magnetic film, and the substrate 10 is used to provide a multilayer coupling pattern. The epitaxial growth of support and continuous thin film layer 20 of magnetic thin film; Patterned thin film layer 30 is formed on continuous thin film layer 20, and patterned thin film layer 30 is discontinuous structure, and patterned thin film layer 30 is used for providing the magnetic field of vortex state. moment distribution.

In the multi-layer coupling patterned magnetic thin film of the embodiment of the present invention, the continuous thin film layer 20 provides out-of-plane magnetic moment distribution and has out-of-plane anisotropy, and the patterned thin film layer 30 has a vortex magnetic structure, which can provide a vortex magnetic moment. The magnetic moment distribution, through the exchange coupling between the two layers of films, the multi-layer coupled patterned magnetic film can form a skyrmion structure, which has various characteristics of skyrmions.

Optionally, the substrate in the multi-layer coupling patterned magnetic thin film in the embodiment of the present invention is made of a material that can make the material on it grow epitaxially, for example: MgO, CrX (X=Ru, Mo, W, Ti) type etc.; the continuous film layer is made of magnetic materials with out-of-plane anisotropy, such as: Co, Co ₃ Pt, CoPt, CoCrPt, FePd, FePt, Fe ₁₄ Nd ₂ B, MnAl, SmCo ₅ , etc.; patterned film The layer is made of soft materials, such as FeNi, Fe ₂ O ₃ , iron-aluminum alloys, amorphous magnetic alloys, and the like.

The substrate of the multilayer coupling patterned magnetic thin film in the embodiment of the present invention can be prepared by MgO, the continuous thin film layer can be prepared by FePt, and the patterned thin film layer can be prepared by FeNi.

The multi-layer coupled patterned magnetic thin film is explained and described below by taking a specific material as an example.

With reference to Fig. 3, have shown the embodiment of the present invention multilayer coupling patterned magnetic thin film three-layer schematic diagram; Wherein, MgO is substrate; FePt is FePt film layer, i.e. continuous film layer; FeNi is FeNi thin film layer, i.e. patterned Thin film layer; MgO as the substrate enables better epitaxial growth of FePt thin film layer; FePt thin film layer is a thin film layer with continuous structure, which provides out-of-plane magnetic moment distribution, has out-of-plane anisotropy, and at the same time through a special process The preparation makes the FePt film layer form an electrode shape, so that the FePt film layer can contribute to the magnetic uniform distribution in the multilayer coupling patterned magnetic film, and can also be used as a means of testing the skyrmion magnetic structure; the FeNi film layer is a non-continuous structure. Thin film layer, which is prepared into a patterned thin film layer according to a certain pattern, which has a vortex magnetic structure and can provide a vortex magnetic moment distribution; through the exchange coupling between the FePt thin film layer and the FeNi thin film layer , so that the multi-layer coupled patterned magnetic film can form a skyrmion structure and possess various properties of skyrmions.

Referring to Fig. 4, it shows the schematic diagram of FePt thin film layer and FeNi thin film layer in the multilayer coupled patterned magnetic thin film of the embodiment of the present invention, in order to make the multilayer coupled patterned magnetic thin film can carry out electrical performance test as a whole, in the embodiment of the present invention The FePt thin film layer is prepared in the shape of Hall Bar, as shown in Figure 4(a), which shows the partial structure of the Hall Bar formed by the FePt thin film layer. The FePt thin film layer is prepared in the shape of Hall Bar, which can not only be used for multi-layer coupling patterning The magnetic uniform distribution in the magnetic thin film contributes, and at the same time, it can be used as the basis for testing the electrical properties of skyrmions. Applying a certain voltage to this layer to generate an electric field meets one of the requirements for testing the electrical properties of skyrmions. The other The condition is to apply a magnetic field, which is described in detail in the corresponding part below, and will not be repeated here.

Figure 4(b) shows a schematic diagram of the enlarged structure of the FeNi thin film layer. The FeNi thin film layer is prepared into a patterned disk array structure. This layer is a discontinuous thin film layer, which has a vortex magnetic The structure can provide the magnetic moment distribution of the vortex state.

Through the exchange coupling effect between the FePt thin film layer and the FeNi thin film layer, the multi-layer coupled patterned magnetic thin film can form a skyrmion structure and have various properties of skyrmions.

It should be noted that in actual operation, the MgO epitaxial layer can be used directly as a substrate, but it can also be used only as an epitaxial layer, and a separate substrate is added below it, and the separately added substrate plays a more important role. It should be noted that if a substrate is added separately, a thin film layer such as an Mgo epitaxial layer must be prepared on the separately added substrate to realize the multilayer coupling patterned magnetic thin film. Epitaxial growth of FePt thin film layers.

The preparation method of the above-mentioned multi-layer coupled patterned magnetic film is as follows:

The FePt thin film was epitaxially grown on MgO by substrate heating method. Firstly, the continuous layer of FePt thin film was prepared in the shape of Hall Bar on MgO by combining photolithography process and magnetron sputtering coating technology.

The process conditions for preparing FePt thin film by magnetron sputtering: Under the condition of background vacuum less than 4.5×10 ^-5 Pa, adjust the sputtering pressure of 0.3 ~ 0.5 Pa, and co-sputter the Fe target and Pt target to coat the film. Among them, the DC sputtering power of the Fe target is 8-20w, the RF sputtering power of the Pt target is 10-35w, Fe and Pt are alternately deposited, based on the formed Hall Bar shape, a Hall Bar-shaped FePt thin film is prepared, Finally, excess photoresist is washed off to obtain a continuous FePt thin film layer.

For the prepared FePt film, a patterned FeNi disk array was prepared on the FePt film by combining the photolithography process and the magnetron sputtering coating technology again.

The process conditions for preparing FeNi thin films by magnetron sputtering: Under the condition that the background vacuum is less than 4.5×10 ^-4 Pa, the sputtering pressure is adjusted to 0.2-0.4 Pa, and the FeNi target is sputtered and coated. Among them, FeNi The DC sputtering power of the target is 40-80w. Based on the formed patterned disk array shape, a patterned disk array-shaped FeNi thin film is prepared, and finally the excess photoresist is washed off to obtain a non- FeNi film layer with continuous structure.

Through the above method, the substrate, the continuous thin film layer and the patterned thin film layer form the multilayer coupled patterned magnetic thin film of the embodiment of the present invention, the thickness of the FePt thin film layer in the magnetic thin film is 10-30nm, and the thickness of the FeNi thin film layer is 20~600nm.

It should be noted that, in the above preparation process, both the FePt thin film layer and the FeNi thin film layer can be adjusted according to specific requirements, and the data in the examples of the present invention only represent one of the optimized data, and do not represent the results of the present invention. The multilayer coupling patterned magnetic thin film of the embodiment can only be the above data.

After the preparation of the multilayer coupling patterned magnetic film is completed, a certain electric field is applied to the FePt film layer by PPMS, and a magnetic field is applied in the direction perpendicular to the magnetic film, and the electrical properties of the multilayer coupling patterned magnetic film are tested to obtain a multilayer Coupling resistance of patterned magnetic films.

Referring to Fig. 5, it shows the embodiment of the present invention multi-layer coupling patterned magnetic thin film electric property test graph, wherein, horizontal axis direction H (T) represents magnetic field strength; Vertical axis R (Ω) represents resistance, and No. 1 curve represents The curve of the resistance of the multilayer coupled patterned magnetic film changing with the change of the magnetic field strength from large to small; Curve No. 2 shows the change of the resistance of the multilayer coupled patterned magnetic film with the change of the magnetic field strength from small to large Curve, the shape of this curve is the same as the electrical performance test curve obtained by relying on DM interaction to form a skyrmion structure in a continuous film. It can be seen that the multilayer coupled patterned magnetic film of the embodiment of the present invention fully meets the characteristics of skyrmions. The test of electrical performance can be obtained directly only through PPMS.

It can be seen from this that the multilayer coupled patterned magnetic thin film of the embodiment of the present invention satisfies the characteristics of skyrmions, and the test of its electrical properties has become extremely convenient and simple. The present invention tests the entire magnetic thin film, so its electrical performance test The results have more reference value for its practical application. The multilayer coupled patterned magnetic film can be widely applied to include but not limited to skyrmion-based track memory devices, logic computing devices, transistor-like functional devices and nanoscale microwave oscillators.

The multilayer coupled patterned magnetic thin film designed in the embodiment of the present invention is combined with sputtering coating technology and photolithography technology to prepare a multilayer coupled patterned magnetic thin film with a discontinuous structure. By making the continuous thin film layer into an electrode shape, it provides a surface The external magnetic moment distribution, as well as the basis for testing the electrical properties of multilayer coupling patterned magnetic films, the patterned film layer is prepared into a discontinuous structure, and the magnetic moment distribution of the vortex state is provided, realizing the use of PPMS for multi- The goal of testing the resistance of the layer-coupled patterned magnetic film at one time solves the problem that the non-continuous structure of the magnetic film needs to be tested one by one with the electrode probe. The completion of the test process is convenient and simple, and the time is very short, which greatly improves the Staff productivity.

It should also be noted that in this article, relational terms such as first and second etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations Any such actual relationship or order exists between. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to cover a non-exclusive inclusion such that a process, method comprising a set of elements includes not only those elements but also other elements not expressly listed, Alternatively, elements inherent in such a process or method may also be included.

A kind of multi-layer coupled patterned magnetic thin film, preparation method and testing method provided by the present invention have been described above in detail. In this paper, specific examples have been used to illustrate the principle and implementation of the present invention. The above examples The description is only used to help understand the method of the present invention and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and scope of application. In summary , the contents of this specification should not be construed as limiting the present invention.

Claims (10)

1. a kind of multi-layer-coupled patterned magnetic film, which is characterized in that the film include: substrate, continuous film layer and Graphical film layer；

The continuous film layer is grown on the substrate, and the continuous film layer forms electrode shape, for outside offer face Magnetic moment distribution, and the basis for testing the electrical property of the multi-layer-coupled patterned magnetic film is provided, the substrate is for mentioning For the support of the multi-layer-coupled patterned magnetic film and the epitaxial growth of the continuous film layer；

The graphical film layer is formed on the continuous film layer, and the graphical film layer is discontinuous structure, institute It states graphical film layer and is distributed for providing the magnetic moment of vortex state.

2. multi-layer-coupled patterned magnetic film according to claim 1, which is characterized in that the continuous film layer is with height Warm assisting growth or the mode of epitaxial growth are grown on the substrate.

3. multi-layer-coupled patterned magnetic film according to claim 1, which is characterized in that the graphical film layer is Patterned array of discs structure.

4. multi-layer-coupled patterned magnetic film according to claim 1, which is characterized in that the continuous film layer is made The standby shape at Hall Bar.

5. multi-layer-coupled patterned magnetic film according to claim 1, which is characterized in that the substrate is prepared by MgO It forms.

6. multi-layer-coupled patterned magnetic film according to claim 2, which is characterized in that the continuous film layer by FePt is prepared.

7. multi-layer-coupled patterned magnetic film according to claim 3, which is characterized in that the graphical film layer by FeNi is prepared.

8. multi-layer-coupled patterned magnetic film according to claim 4, which is characterized in that when externally-applied magnetic field is perpendicular to institute When stating multi-layer-coupled patterned magnetic film, the resistance of the multi-layer-coupled patterned magnetic film is with the externally-applied magnetic field Change and change, and is identical as including the resistance of multi-layer-coupled patterned magnetic film of continuous structure.

9. a kind of preparation method of multi-layer-coupled patterned magnetic film, which is characterized in that the described method includes:

Using the method for silicon on MgO epitaxial growth FePt film, and by Fe target and Pt target co-sputtering, preparing can The FePt film of adjustment, obtains continuous film layer；

Adjustable FeNi film is prepared, i.e., by FeNi target as sputter for the adjustable FePt film prepared Obtain graphical film layer；Wherein, the substrate, the continuous film layer and the graphical film layer form claim Any multi-layer-coupled patterned magnetic film of 1-8；

By Fe target and Pt target co-sputtering, adjustable FePt film is prepared, comprising:

Under conditions of base vacuum is less than 4.5 × 10-5Pa, adjusting obtains the sputtering pressure of 0.3~0.5Pa, Fe target it is straight Stream sputtering power is 8~20w, and the rf sputtering power of Pt target is 10~35w, passes through Fe target and Pt target co-sputtering, alternating deposit To obtain FePt film；

Wherein, by FeNi target as sputter, the graphical film layer of FeNi is prepared, comprising:

Under conditions of back end vacuum is less than 4.5 × 10-4Pa, adjusting obtains the sputtering pressure of 0.2~0.4Pa, FeNi target The power of d.c. sputtering be that 40~80w by FeNi target as sputter obtains FeNi film.

10. a kind of test method of the electrical property of multi-layer-coupled patterned magnetic film, which is characterized in that comprehensive physical measurement system System applies magnetic field with the direction perpendicular to any multi-layer-coupled patterned magnetic film of claim 1-8, to obtain The resistance of multi-layer-coupled patterned magnetic film is stated, which changes with the variation of externally-applied magnetic field, and ties with including continuous The resistance of the multi-layer-coupled patterned magnetic film of structure is identical.