CN114337372A - MEMS energy harvester and method of making the same - Google Patents

Abstract

The technical problem to be solved by the present invention is to provide a MEMS energy harvester and a manufacturing method thereof, which can improve the conversion efficiency between the vibration mechanical energy of the magnetic element and the electrical energy. In order to solve the above problems, the present invention provides a MEMS energy harvester, comprising: a substrate, the substrate has a hollow part; a magnetic core, the magnetic core is movably arranged in the hollow part; a coil, the The coil is embedded in the substrate and arranged around the magnetic core and the hollow part; the cantilever beam connects the magnetic core and the substrate, and the cantilever beam includes a piezoelectric material layer. In the MEMS energy harvester involved in the above technical solution, the magnetic core is precisely arranged in the plane where the coil is located, and is suspended by the piezoelectric material layer. Therefore, when the magnetic core moves, the kinetic energy can be converted into electrical energy through the coil and the piezoelectric material layer at the same time with maximum efficiency, and the energy collection efficiency can be improved.

Description

MEMS energy harvester and method of making the same

technical field

The invention relates to the field of micromachines, in particular to a MEMS energy harvester and a manufacturing method thereof.

Background technique

Energy harvesters are an important element in the field of micromechanics. The element collects the electromagnetic wave energy in the environment through the resonance of the magnetic element and converts it into electrical energy. The element can be used for signal acquisition and signal conversion, and can also be used in reverse for energy output. No matter what the application is, an important problem that the component needs to solve is how to efficiently realize the conversion between the vibration mechanical energy and the electrical energy of the magnetic component.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a MEMS energy harvester and a manufacturing method thereof, which can improve the conversion efficiency between the vibration mechanical energy of the magnetic element and the electrical energy.

In order to solve the above problems, the present invention provides a MEMS energy harvester, comprising: a substrate, the substrate has a hollow part; a magnetic core, the magnetic core is movably arranged in the hollow part; a coil, the The coil is embedded in the substrate and arranged around the magnetic core and the hollow part; the cantilever beam connects the magnetic core and the substrate, and the cantilever beam includes a piezoelectric material layer.

In order to solve the above problems, the present invention provides a manufacturing method of a MEMS energy harvester, which includes the following steps: providing a substrate; burying a coil in the substrate; forming a cantilever beam on the surface of the coil, the cantilever A piezoelectric material layer is included in the beam; a hollow portion is formed in the substrate surrounded by the coil, and a suspended magnetic core is formed in the hollow portion, and the magnetic core is connected to the suspended portion of the cantilever beam. fixed.

In the energy harvester involved in the above technical solution, the magnetic core is precisely arranged in the plane where the coil is located, and is suspended by the piezoelectric material layer. Therefore, when the magnetic core moves, the kinetic energy can be converted into electrical energy with maximum efficiency through the coil and the piezoelectric material layer at the same time, so as to improve the energy collection efficiency.

Description of drawings

FIG. 1 is a schematic diagram of the implementation steps of a specific embodiment of the manufacturing method of the MEMS energy harvester according to the present invention.

FIG. 2A to FIG. 2H show a process flow diagram of a specific embodiment of the method for manufacturing a MEMS energy harvester according to the present invention.

FIG. 3 is a schematic diagram of the implementation steps of a specific embodiment of the manufacturing method of the MEMS energy harvester according to the present invention.

FIG. 4A to FIG. 4C are process flow diagrams of a specific embodiment of the method for manufacturing a MEMS energy harvester according to the present invention.

Detailed ways

The specific embodiments of the MEMS energy harvester and the manufacturing method thereof provided by the present invention will be described in detail below with reference to the accompanying drawings.

1 is a schematic diagram of the implementation steps of a specific embodiment of the MEMS energy harvester manufacturing method according to the present invention, including: step S10, providing a substrate; step S11, forming a trench in the substrate; step S12 , embed metal material in the trench to form a coil; step S13, form a piezoelectric induction composite layer on the front side of the substrate; step S14, pattern the piezoelectric induction composite layer to form a cantilever beam; step S15, reduce The backside of the substrate is thinned; step S16, a hollow portion is formed in the substrate surrounded by the coil; step S17, a magnetic mass is assembled and bonded from the backside to a cantilever beam to form a magnetic core.

As shown in FIG. 2A, referring to step S10, a substrate 20 is provided. The material of the substrate 20 may be single crystal silicon, or any other common substrate material.

As shown in FIG. 2B , referring to step S11 , trenches 21 are formed in the substrate 20 . The method for forming the trench 21 includes, but is not limited to, dry etching or wet etching, and a suitable etching gas or etching solution is used to form the trench 21 with a predetermined shape. Since the purpose of the groove 21 is to serve as a accommodating space for forming a coil, the shape of the groove 21 in a top view should be selected from one of concentric circular closed shapes, such as a circle, a rectangle, and a polygon, and communicate with the inside and outside.

As shown in FIG. 2C , referring to step S12 , a metal material is embedded in the trench 21 to form the coil 22 . The process of burying the metal material is selected from one of electroplating and liquid metal filling. During the growth process, a continuous metal layer may be firstly covered on the surface of the substrate, and then the metal layer on the surface may be removed through an etching or grinding process to retain the metal material in the trench 21 to form the coil 22 .

After the above steps S11 and S12 are completed, the coil is embedded in the substrate. In other specific embodiments, sputtering, evaporation, and physical vapor deposition processes can also be selected to bury the metal, and the process of forming the trench 21 is not limited to dry etching or wet etching. In other specific embodiments, the coil 22 may also be formed on the surface of the substrate by first forming a continuous metal layer, then patterning it into a coil, and filling the gap of the coil with an insulating medium.

As shown in FIG. 2D , referring to step S13 , a piezoelectric induction composite layer 23 is formed on the surface of the coil 22 . In this specific embodiment, the piezoelectric induction composite layer 23 sequentially includes a first insulating layer 221 , a first electrode layer 222 , a piezoelectric material layer 223 , a second electrode layer 224 , and a second electrode layer 224 from the surface of the coil 22 . Two insulating layers 225 . The materials of the first insulating layer 221 and the second insulating layer 225 can be independently selected from any one of silicon oxide, silicon nitride, and silicon oxynitride, and are formed by an epitaxial process. The materials of the first electrode layer 222 and the second electrode layer 224 are metal materials, and are formed by sputtering, evaporation, and physical vapor deposition processes. The material of the piezoelectric material layer 223 is piezoelectric ceramics or aluminum nitride.

As shown in FIG. 2E , referring to step S14 , the piezoelectric induction composite layer 23 is patterned to form a cantilever beam 24 . The patterning process adopts dry etching or wet etching, and selects different etching or etching processes for different materials to form the cantilever beam 24 composed of the piezoelectric induction composite layer 23 including the piezoelectric material layer 223 . In particular, the cantilever beam 24 is connected to the coil 22 and extends to the area surrounded by the coil 22 to facilitate subsequent pattern release.

After the above steps S13 and S14 are completed, a cantilever beam 24 is formed on the surface of the coil 22 , and the cantilever beam 24 includes a piezoelectric material layer 223 . In other specific embodiments, the cantilever beam structure can also be formed first, and then the piezoelectric composite layer can be defined on the cantilever beam by using photolithography and etching processes, which should also be regarded as an optional embodiment of the above technical solution. .

As shown in FIG. 2F , referring to step S15 , the backside of the substrate 20 is thinned. The thinning process can use mechanical grinding, chemical etching, and mechanical grinding combined with chemical etching.

As shown in FIG. 2G , referring to step S16 , a hollow portion 25 is formed in the substrate 20 surrounded by the coil 22 . Dry etching or wet etching can be used to form the hollow part 25 by using a suitable etching gas or etching solution. Since the cantilever beam 24 extends to the area surrounded by the coil 22 , the cantilever beam 24 is in a suspended state after the hollow portion 25 is formed. In this specific embodiment, the free end of the cantilever beam 24 is suspended, but in another specific embodiment, both ends of the cantilever beam may be fixed to the surface of the coil 22 , and the middle part is suspended from the hollow portion 25 .

As shown in FIG. 2H, referring to step S17, a magnetic mass 26 is assembled and bonded to the cantilever beam from the back side to form a magnetic core. The material of the magnetic core is metal or magnetic polymer composite material, and adhesives such as epoxy resin can be used for bonding, and the micro-assembly method is used. In this specific embodiment, the magnetic mass 26 is a movable magnetic core.

The purpose of the above steps S15 to S17 is to hollow out the substrate 20 surrounded by the coil 22 to form a hollow portion 25 , and to form a suspended magnetic core in the hollow portion 25 , the magnetic core and the The suspended portion of the cantilever beam 24 is fixedly connected. In this specific embodiment, the magnetic core is a magnetic mass 26 .

After the above steps are completed, a MEMS energy harvester is obtained, as shown in FIG. 2H , including a substrate 20 , a magnetic mass 26 , a coil 22 and a cantilever beam 24 . The substrate 20 has a hollow portion 25 . The magnetic core, which is the magnetic mass 26 in the present embodiment, is movably arranged in the hollow portion 25 . The coil 22 is embedded in the substrate 20 and disposed around the magnetic mass 26 and the hollow portion 25 . The cantilever beam 24 connects the magnetic mass 26 and the substrate 20 , and the cantilever beam 25 includes a piezoelectric material layer 223 therein.

In the above structure, the magnetic core is precisely arranged in the plane where the coil is located, and is suspended by the piezoelectric material layer. Therefore, when the magnetic core moves, the kinetic energy can be converted into electrical energy with maximum efficiency through the coil and the piezoelectric material layer at the same time, so as to improve the energy collection efficiency.

3 is a schematic diagram of the implementation steps of a specific embodiment of the MEMS energy harvester manufacturing method according to the present invention, including: step S30, providing a substrate; step S31, forming a trench in the substrate; step S32 , embed metal material in the trench to form a coil; step S33, form a piezoelectric induction composite layer on the front side of the substrate; step S34, pattern the piezoelectric induction composite layer to form a cantilever beam; step S35, reduce Thin the back of the substrate; Step S36, form a through hole in the substrate from the back at a position corresponding to the cantilever beam; Step S37, fill the through hole with a magnetic material to form a magnetic core; Step S38, remove all The substrate material between the magnetic core and the coil forms a hollow part in the substrate surrounded by the coil, and the magnetic core is suspended.

For the description of steps S30 to S35, refer to the previous specific embodiment.

As shown in FIG. 4A , referring to step S36 , a through hole 36 is formed in the substrate 20 from the back at a position corresponding to the cantilever beam 24 . Dry etching or wet etching can be used to form the through hole 36 by using a suitable etching gas or etching solution.

As shown in FIG. 4B , referring to step S37 , the through hole 36 is filled with a magnetic material to form a magnetic core 37 . The material of the magnetic core is metal or magnetic polymer composite material, which can be formed by electroplating, liquid metal filling, sputtering, evaporation, and physical vapor deposition processes. The filling step may be to form a continuous metal layer first, and then polish or etch to form a filling structure.

As shown in FIG. 4C , referring to step S38 , the substrate material between the magnetic core 37 and the coil 22 is removed, a hollow portion 35 is formed in the substrate 20 surrounded by the coil 22 , and the The magnetic core 37 is suspended. The removal process can be dry etching or wet etching, and different etching or etching processes are selected for different materials.

The purpose of the above steps S35 to S38 is to hollow out a hollow portion 35 in the substrate 20 surrounded by the coil 22 , and to form a suspended magnetic core 37 in the hollow portion 35 . The suspended portion of the cantilever beam 24 is fixedly connected.

After the above steps are completed, a MEMS energy harvester is obtained, as shown in FIG. 4C , including the substrate 20 , the magnetic core 37 , the coil 22 and the cantilever beam 24 . The substrate 20 has a hollow portion 35 . The magnetic core 37 is movably arranged in the hollow portion 35 . The coil 22 is embedded in the substrate 20 and disposed around the magnetic core 37 and the hollow portion 35 . The cantilever beam 24 connects the magnetic core 37 and the substrate 20 , and the cantilever beam 25 includes a piezoelectric material layer 223 therein.

In the above structure, the magnetic core is precisely arranged in the plane where the coil is located, and is suspended by the piezoelectric material layer. Therefore, when the magnetic core moves, the kinetic energy can be converted into electrical energy with maximum efficiency through the coil and the piezoelectric material layer at the same time, so as to improve the energy collection efficiency.

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 also be made, and these improvements and modifications should also be regarded as It is the protection scope of the present invention.

Claims (10)

1. A MEMS energy harvester, comprising:

the substrate is provided with a hollow part;

a magnetic core movably disposed within the hollow portion;

a coil embedded in the substrate and provided in a three-dimensional manner around the magnetic core and the hollow portion;

the cantilever beam is connected with the magnetic core and the substrate, and a piezoelectric material layer is arranged in the cantilever beam.

2. The MEMS energy harvester of claim 1, wherein the magnetic core is a metal or a magnetic polymer composite.

3. The MEMS energy harvester of claim 1, wherein the substrate is a monocrystalline silicon substrate.

4. A manufacturing method of an MEMS energy harvester is characterized by comprising the following steps:

providing a substrate;

embedding a coil in the substrate;

forming a cantilever beam on the surface of the coil, wherein the cantilever beam comprises a piezoelectric material layer;

and hollowing out the position surrounded by the coil in the substrate to form a hollow part, and forming a suspended magnetic core in the hollow part, wherein the magnetic core is fixedly connected with the suspended part of the cantilever beam.

5. The method of claim 4, wherein the step of forming the hollow portion and the magnetic core further comprises:

thinning the back surface of the substrate;

forming a hollow portion in the substrate where the coil surrounds;

and bonding a magnetic mass block to the cantilever beam from the back side to form the magnetic core.

6. The method of claim 4, wherein the step of forming the hollow portion and the magnetic core further comprises:

thinning the back surface of the substrate;

forming a through hole at a position corresponding to the cantilever beam in the substrate from the back surface;

filling the through hole with a magnetic material to form a magnetic core;

and removing the substrate material between the magnetic core and the coil, forming a hollow part in the substrate where the substrate is surrounded by the coil, and enabling the magnetic core to be in a suspension shape.

7. The method of claim 4, wherein said step of embedding the coil further comprises: forming a trench in the substrate;

and embedding a metal material in the groove to form a coil.

8. The method of claim 7, wherein the process of embedding the metal material is selected from one of electroplating and liquid metal filling.

9. The method of claim 4, wherein the step of forming the cantilever beam further comprises:

forming a piezoelectric induction composite layer on the surface of the coil;

and patterning the piezoelectric induction composite layer to form the cantilever beam.

10. The method of claim 9, wherein the piezoelectric induction composite layer comprises a first insulating layer, a first electrode layer, a piezoelectric material layer, a second electrode layer, and a second insulating layer in this order from the surface of the coil.

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