KR101340143B1 - Piezoelectric-magnetic micro device, magnetic sensor including the same, and fabrication method of piezoelectric-magnetic micro device - Google Patents

Abstract

The present invention can maximize the magnetoelectric effect coefficient by forming an ultra-small size MEMS structure in which a piezoelectric material and a magnetic material are integrated, and a piezo-magnetic micro device that can be applied to the implementation of an ultra-small magnetic sensor or a current sensor and its It relates to a manufacturing method. A piezoelectric-magnetic micro device according to an embodiment of the present invention may include a piezoelectric body including a support layer, a lower electrode layer, a piezoelectric thin film layer, and an upper electrode layer formed in a stacked manner on the support layer, an insulating layer covering the piezoelectric material, and an insulating layer on the insulating layer. And a magnetic thin film layer formed, wherein the support layer, the piezoelectric material, and the insulating layer form a cantilever structure, and the magnetic thin film layer is formed on the protrusion of the cantilever structure.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric-magnetic micro-device, a magnetic sensor including the same, and a manufacturing method of the piezoelectric-magnetic micro-device. 2. Description of the Related Art Piezoelectric-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite device of a piezoelectric material and a magnetic material for generating a magnetoelectric effect and a method of manufacturing the same.

The effect of magnetism is a phenomenon in which magnetization occurs in proportion to an electric field when an electric field is applied to the crystal, or conversely, electric polarization occurs in proportion to a magnetic field when a magnetic field is applied to the crystal. Such a magnetism effect can be applied to a technical field such as a magnetic sensor, a current sensor, a micro-transformer, a gyro sensor, etc., and it is possible to use a MEMS (Micro Electro Mechanical System) It is possible to realize a very small and very fine sensor.

In general, dielectric and magnetic materials rarely cause coupling, that is, magnetization under an electric field, but research has shown that magnetoelectric effects occur in a single material. Was found. Due to these findings, material studies such as the layered structure of a single layer, a composite or a magnetic body and a piezoelectric body are currently being conducted, and a study for obtaining an optimal magnetoelectric coupling coefficient is mainly performed. Actively done.

However, at present, there is little research on the fabrication of devices using magnetoelectric effects and their application to sensors. In particular, the ultra-fine magnetic sensor or current sensor is considered to be applicable to the smart grid (Smart Grid), which is currently in the spotlight, but there is almost no research on this.

The present invention can maximize the magnetoelectric effect coefficient by forming an ultra-small size MEMS structure in which a piezoelectric material and a magnetic material are integrated, and a piezo-magnetic micro device that can be applied to the implementation of an ultra-small magnetic sensor or a current sensor and its It is an object to provide a manufacturing method.

In accordance with an embodiment of the present invention, a piezoelectric-magnetic micro device includes a support layer, a piezoelectric body including a lower electrode layer, a piezoelectric thin film layer, and an upper electrode layer formed in a stacked shape on the support layer, and an insulating layer covering the piezoelectric body. And a magnetic thin film layer formed on the insulating layer, wherein the support layer, the piezoelectric material, and the insulating layer form a cantilever structure, and the magnetic thin film layer is formed on the protrusion of the cantilever structure.

Method of manufacturing a piezo-magnetic micro device according to an embodiment of the present invention, the step of sequentially depositing a lower electrode layer, a piezoelectric thin film layer and an upper electrode layer on the support layer, photolithography and etching on the upper electrode layer, the piezoelectric thin film layer and the lower electrode layer. Forming a piezoelectric material by sequentially performing the process; depositing an insulating layer on the piezoelectric body; etching a lower portion of the support layer to form a cantilever structure; and forming a magnetic thin film layer on an insulating layer of the protrusion of the cantilever structure. Depositing. The method may further include annealing the magnetic thin film layer at or below the phase transition temperature of the piezoelectric material during or after the deposition of the magnetic thin film layer.

According to the present invention, the magnetoelectric effect generated in the piezo-magnetic micro device can be maximized by forming the support layer and the piezoelectric body in a cantilever structure and forming a magnetic thin film layer on the entire upper surface of the protruding portion.

Also, a micro-sized magnetic sensor or current sensor having a high sensitivity can be realized by inducing a magneto-electric effect in the piezoelectric-magnetic micro element and generating an electric signal corresponding to the surrounding magnetic field or current field.

In addition, by using the electric energy generated in the piezoelectric body of the piezoelectric-magnetic micro element as the power source of the sensor, it is possible to perform the non-power operation, and it can be applied to various fields such as renewable energy, smart grid and automobile.

In addition, mass production is possible by applying general MEMS process, and price competitiveness can be greatly enhanced compared to existing high sensitivity sensor module.

1 is a block diagram of a piezo-magnetic micro device according to an embodiment of the present invention.
2A to 2G illustrate a method of manufacturing a piezo-magnetic micro device according to an embodiment of the present invention.
3 is a view showing magnetization characteristics before and after heat treatment of a magnetic thin film layer formed of Terfenol-D material.
4 and 5 show the results of measuring the amount of charge induced in the piezoelectric body when a microcurrent is applied to the piezoelectric-magnetic micro device according to the present invention.

The above and other objects, features, and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, which are not intended to limit the scope of the present invention. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a piezo-magnetic micro device according to an embodiment of the present invention.

Referring to FIG. 1, a piezoelectric-magnetic micro device according to an exemplary embodiment of the present invention may include a support layer 100, a lower electrode layer 111, a piezoelectric thin film layer 113, and an upper electrode layer formed on the support layer 100 in a stacked form. A piezoelectric body 110 including a 115, an insulating layer 120 covering the piezoelectric body 110, and a magnetic thin film layer 130 formed on the insulating layer 120 are included. The support layer 100, the piezoelectric body 110, and the insulating layer 120 form a cantilever structure, and the magnetic thin film layer 130 is formed on the protrusion of the cantilever structure.

The support layer 100 may be formed of a material including at least one of SiNx, poly-Si, SiO2 and Al, and the lower electrode layer 111 and the upper electrode layer 115 stacked thereon may be formed of Pt, The piezoelectric thin film layer 113 between the electrode layers 111 and 115 may be formed of a material including at least one of PZT, PMN-ZT, PVDF, and BaTiO3. The insulating layer 120 covering the piezoelectric body 110 as a whole may be formed using SiO 2 or parylene, and the magnetic thin film layer 130 on the insulating layer 120 may be Terfenol-D, NiFe 2 O 4, Ni, Metglass, and Permendur. It may be formed of a material containing at least one of. Here, the protrusion of the cantilever structure is preferably formed with a width of 1 to 500 μm, a length of 1 to 4 times the width, and a thickness of 0.1 to 10 μm, and the piezoelectric thin film layer 113 and the magnetic thin film layer 130. Silver is preferably formed to a thickness of 0.01 ~ 4㎛.

The piezo-magnetic micro device of the present invention can be used as an ultra-small high sensitivity magnetic sensor or current sensor by inducing and maximizing magnetoelectric effect. To this end, the piezoelectric body 110 and the magnetic thin film layer 130 form an integrated micro size cantilever structure with the insulating layer 120 interposed therebetween, and the magnetic thin film layer 130 is formed on the entire upper surface of the protruding portion of the cantilever structure. The mechanical strain caused by the magnetic field change is maximized to maximize the coupling effect by the electromagnetic coefficient. At this time, due to the mechanical strain generated in the magnetic thin film layer 130, the piezoelectric element 110 changes the amount of charge (or voltage), that is, an electric signal is generated, and the magnitude and change of the surrounding magnetic or electric field are measured by measuring the magnitude. It can be detected.

In addition, the magnetic sensor or the current sensor using the piezo-magnetic micro device of the present invention can use the electrical energy generated in the piezoelectric body 110 by the magnetoelectric effect as a power source, so that a separate power source for driving the sensor circuit is provided. It is not necessary. That is, since the power supply operation through self-generation is possible, the miniaturization of the sensor becomes easier.

On the other hand, as shown in the upper end of Figure 1, the magnetic sensor using the piezo-magnetic micro device of the present invention may be implemented in the form of a cantilever array (array) including a plurality of micro devices. In this case, a plurality of microelements of the cantilever structure may be formed in pairs with each other. One of the paired cantilevers may be formed in a structure in which a magnetic thin film layer is formed on the piezoelectric body and the magnetic thin film layer is not formed in the other ( Not shown). This enables more precise sensing by canceling changes in the external environment other than changes in the magnetic field or current, such as changes in external temperature and humidity.

2A to 2G illustrate a method of manufacturing a piezo-magnetic micro device according to an embodiment of the present invention.

2A to 2G, a method of manufacturing a piezoelectric-magnetic micro device according to an embodiment of the present invention includes a lower electrode layer 111, a piezoelectric thin film layer 113, and an upper electrode layer 115 on a support layer 100. Depositing sequentially, forming a piezoelectric body 110 by sequentially performing photolithography and etching processes on the upper electrode layer 115, the piezoelectric thin film layer 113, and the lower electrode layer 111; Depositing an insulating layer 120 on the piezoelectric body 110, etching a lower portion of the support layer 100 to form a cantilever structure, and forming a magnetic thin film layer 130 on the insulating layer 120 of the protrusion of the cantilever structure. Depositing.

First, as shown in FIG. 2A, a material including at least one of SiNx, poly-Si, SiO 2, and Al is used as the support layer 100, and a sol-gel method, a sputtering method, or a CVD (Chemical) is disposed thereon. The lower electrode layer 111, the piezoelectric thin film layer 113, and the upper electrode layer 115 are deposited by using a vapor deposition method to form a multilayer substrate. Here, a material including Pt as the lower electrode layer 111 and the upper electrode layer 115 and at least one of PZT, PMN-ZT, PVDF, and BaTiO 3 may be used as the piezoelectric thin film layer 113.

Subsequently, as illustrated in FIG. 2B, the upper electrode layer 115 is etched through photolithography and etching, and the piezoelectric thin film layer 113 and the lower electrode layer 111 are etched as in FIGS. 2C and 2D. Form.

Next, as illustrated in FIG. 2E, the insulating layer 120 is deposited on the piezoelectric body 110 using a material such as SiO 2 or parylene. Through such an insulating layer 120, it is possible to remarkably prevent the movement of current in the piezoelectric body that generates the magnetic thin film and electricity.

Subsequently, as shown in FIG. 2F, the lower portion of the support layer 100 is etched to form a cantilever structure. The cantilever structure is preferably formed to have a width of 1 to 500 µm, a length of 1 to 4 times the width, and a thickness of 0.1 to 10 µm.

Subsequently, as illustrated in FIG. 2G, the magnetic thin film layer 130 is deposited on the insulating layer 120 of the protrusion of the cantilever structure by using a magnetic material such as Terfenol-D, NiFe 2 O 4, Ni, Metglass, or Permendur.

In this case, the magnetic thin film layer 130 may be subjected to in-situ annealing or post-annealing. In particular, when Terfenol-D material is used as the magnetic thin film layer 130, a heat treatment process is required. The heat treatment is preferably performed at or below the phase transition temperature of the piezoelectric body 110.

3 is a view showing magnetization characteristics before and after heat treatment of a magnetic thin film layer formed of Terfenol-D material.

In Figure 3, the horizontal axis represents the magnitude of the magnetic field, the vertical axis represents the degree of magnetization (magnetization) of the thin film. The line of red dots is the MH hysterisis curve after heat treatment before the heat treatment. As such, the magnetic thin film layer 130 deposited with the Terfenol-D material has a characteristic of the magnetic material only after the heat treatment process.

4 and 5 illustrate the results of measuring the amount of charge induced in a piezoelectric body when a microcurrent is applied to the piezoelectric-magnetic micro device according to the present invention.

Measure the amount of charge induced in the piezoelectric body 110 according to the deformation of the magnetic thin film layer 130 after flowing a current using an electromagnet, a conductive wire and a Helmholtz coil to the manufactured piezo-magnetic micro device It was.

First, the current was increased to 10 kV, 25 kV, 50 kV, 75 kV, and 100 kV for 5 seconds without the cantilever structure, and as a result, almost no reaction occurred as shown in the red line below the graph of FIG. On the other hand, after forming the cantilever structure and increasing the current to 10 ㎂, 25 ㎂, 50 ㎂, 75 실험, 100 실험, the experiment result, the amount of charge proportional to the magnitude of the applied current as shown in the green line in the center of the graph This was measured.

5 shows the amount of charge induced when a minimum current of 0.005 mA is applied, and the minimum detection limit at this time was measured to be about 10 ^-12 T (10 ^-16 Gauss). Through this, it can be seen that the piezoelectric-magnetic micro device according to the present invention can realize a high sensitivity and a small current sensor or a magnetic sensor.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention.

100: Support layer 110:
111: lower electrode layer 113: piezoelectric thin film layer
115: upper electrode layer 120: insulating layer
130: magnetic thin film layer

Claims (8)

Supporting layer;
A piezoelectric body including a lower electrode layer, a piezoelectric thin film layer, and an upper electrode layer formed on the support layer in a stacked form;
An insulating layer covering the piezoelectric body; And
A magnetic thin film layer formed on the insulating layer,
The support layer, the piezoelectric material, and the insulating layer form a cantilever structure, and the magnetic thin film layer is formed on the protrusion of the cantilever structure.
The lower electrode layer and the upper electrode layer are formed of Pt, and the piezoelectric thin film layer is formed of a material including at least one of PZT, PMN-ZT, PVDF, and BaTiO3.
Piezoelectric - magnetic microdevices.
The method of claim 1,
When a strain is generated in the magnetic thin film layer due to a change in a peripheral magnetic field, the piezoelectric element generates an electrical signal corresponding to the strain.
Piezoelectric - magnetic microdevices.
delete The method of claim 1,
The magnetic thin film layer is formed of a material containing at least one of Terfenol-D, NiFe2O4, Ni, Metglass, and Permendur
Piezoelectric - magnetic microdevices.
In a magnetic sensor including a plurality of micro elements,
Wherein the plurality of micro elements are formed in pairs with each other,
The plurality of micro devices commonly include a support layer having a cantilever structure, a piezoelectric body including a lower electrode layer, a piezoelectric thin film layer, and an upper electrode layer stacked on the support layer, and an insulating layer covering the piezoelectric body.
One of the paired micro devices includes a magnetic thin film layer formed on the insulating layer, and the other does not include the magnetic thin film layer.
Magnetic sensor.
Sequentially depositing a lower electrode layer, a piezoelectric thin film layer, and an upper electrode layer on the support layer;
Forming a piezoelectric material by sequentially performing photolithography and etching processes on the upper electrode layer, the piezoelectric thin film layer, and the lower electrode layer;
Depositing an insulating layer on the piezoelectric body;
Etching a lower portion of the support layer to form a cantilever structure; And
Depositing a magnetic thin film layer on an insulating layer of the protrusion of the cantilever structure
Piezo-magnetic micro device manufacturing method comprising a.
The method according to claim 6,
The magnetic thin film layer is deposited using a sputtering method with a material containing at least one of Terfenol-D, NiFe 2 O 4, Ni, Metglass, and Permendur.
Method of manufacturing piezo-magnetic microdevices.
8. The method of claim 7,
When the magnetic thin film layer is formed of the Terfenol-D material, annealing the magnetic thin film layer during or after the deposition of the magnetic thin film layer.
Method of manufacturing a piezo-magnetic micro device further comprising.

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