AU2020101712A4

AU2020101712A4 - A MEMS miniaturized solenoid transformer and its manufacturing method

Info

Publication number: AU2020101712A4
Application number: AU2020101712A
Authority: AU
Inventors: Yujia Huang; Haiwang LI; Jiamian Sun; Zhi TAO; Hanxiao WU; Jingchao Xia; Tiantong XU; Kaiyun ZHU
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2020-08-07
Filing date: 2020-08-07
Publication date: 2020-09-17
Anticipated expiration: 2028-08-07

Abstract

In the MEMS miniature solenoid transform, a silicon substrate, a soft magnetic core, a first solenoid and a second solenoid are disposed, and the soft magnet core is wrapped inside the silicon substrate. The silicon substrate is disposed with a first spiral channel and a second spiral channel, and the soft magnetic core passes through the centers of the first and second spiral channels, a first solenoid and a second solenoid are disposed in the first helical channel and the second helical channel. In this manufacture method, an upper silicon substrate and a lower silicon substrate are made; an upper iron core and a low iron core are formed by electroplating; A first helical channel and a second helical channel are formed, and a first solenoid and second solenoid are electroplated. In this invention, the soft magnetic iron core, the first solenoid and the second solenoid are arranged inside the silicon substrate, so that the cross-sectional area of the transformer winding can be increased, the magnetic flux is higher, with high inductance value; The silicon substrate protect the soft magnetic iron core, the first solenoid and the second solenoid, which improves the strength of the transform, and has good impact resistance. 1/7 5 12 22 Figure 1 33F Figure 2

Description

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AUSTRALIA

PATENTS ACT 1990

PATENT SPECIFICATION FOR THE INVENTION ENTITLED:

A MEMS miniaturized solenoid transformer and its manufacturing method

The invention is described in the following statement:-

A MEMS miniaturized solenoid transformer and its manufacturing method

TECHNICAL FIELD

The embodiments of the application relate to the field of micro electromechanical systems (MEMS) technology, and more particularly, to a MEMS solenoid transformer and a method of manufacturing thereof.

BACKGROUND

In a micro-electro-mechanical system (MEMS), electric energy is transferred between two circuits by micro-transformer applying an electromagnetic induction principle, which is composed of a magnetic core and a winding. Compared with the conventional transformer, the magnetic core is greatly reduced in size, the winding form has also changed. Micro-transformer is widely used in micro-electronic equipment and information equipment, and can play the role of voltage transformation, current transformation, impedance transformation, isolation and voltage stabilization.

The miniaturized transformer is suitable for the miniaturization of electronic devices, so the miniaturization is the development trend of the transformer.

There are two fabrication methods for miniaturized transformers:

1. Traditional mechanical processing method, that is, winding method are adopted. This method is essentially the processing technology of the common size transformer. With the reduction of the size of the transformer, the problems of electrical insulation, high cost and low output will occur in this method, so it is difficult to further miniaturize;

2. Adopting professional MEMS(Micro-Electro-Mechanical System) process. MEMS processing method is a new type of process which is developed to fabricate micro devices, and this patent is a kind of transformer based on MEMS process. The micro-transformer based on MEMS process has low cost of manufacture, small size, and it is favorable for integration and large-scale production.

Micro-transformer based on MEMS technology is mainly divided into two kinds: planar spiral type and solenoid type. For the transformer with planar spiral structure, as the number of turn of the winding increases, the diameter of the coil becomes large, and the total magnetic flux along the iron core does not linearly increase but the increment gradually decreases, so that the number of turns of this structure is generally limited. As a result, the total power increase of the transformer has a bottleneck, and the working efficiency and the energy density will decrease as the number of turns of transformer increases. At present, most of MEMS micro transformers are planar spiral transformers fabricated by thin film manufacturing process and few people can complete the design and manufacture of three dimensional solenoid micro-transformer.

SUMMARY

The present application provides a MEMS solenoid transformer and method thereof overcomes, or at least partially solves, the above-described problems.

In order to achieve the above object, the present invention provides a MEMS solenoid transformer, which can not only freely adjust the turns and the turns ratio of primary and secondary coils, but also the inductance density and the working efficiency do not significantly decrease as the number of turns increases. It is characterized by as follows: A silicon substrate, a soft magnetic core and two solenoids; wherein, the soft magnetic iron core is wrapped in the silicon substrate and passes through the center of the spiral channel arranged on the silicon substrates, and the solenoid is arranged in the helical channel;

The silicon substrate comprises an upper silicon substrate and a lower silicon substrate, and the soft magnetic core comprises the upper core and the lower core with the same shape;

A lower surface of the upper silicon substrate is disposed with a core slot corresponding to an upper core shape, and an upper surface of a lower silicon substrate with core slots corresponding to a lower core shape, in which upper and lower cores are respectively disposed, and a lower surface of the upper silicon substrate and an upper surface of a lower silicon substrate are bonded to each other;

The spiral channel comprises a plurality of first horizontal grooves disposed on an upper surface of the silicon substrate, a plurality of second horizontal grooves disposed on a lower surface thereof. The vertical through-holes penetrate vertically through the upper surface and the lower surface of the silicon substrate, and any of is the first horizontal trenches are connected with two vertical holes respectively, and the two horizontal holes are connected with two adjacent second horizontal trenches respectively.

The solenoid includes a first solenoid disposed within the first helical aperture and a second solenoid disposed within the second helical aperture;

The spiral channel is obtained by a deep etching process with a high aspect ratio, so that the size of the micro solenoid transformer can be made smaller, the inductance density is larger, and the performance is better;

The upper iron core and the lower iron core are directly formed by plating in the iron core slots of the upper silicon substrate and lower silicon substrate.

The upper silicon substrate and the lower silicon substrate are bonded with low temperature bonding process, and then spiral channels are formed in the bonded upper and lower silicon substrates, which also include four pins and four pin slots;

The four pin slots are arranged on the upper surface of the silicon substrate, two pin slots of the four pin slots are respectively communicated with the leading and trailing ends of the first spiral channel, the other two pin slots of the four pin slots are respectively communicated with the leading and trailing ends of the second spiral channel, and the four slots are respectively arranged in the 4 pin slots.

The soft magnetic core is made of iron-nickel alloy material or iron-cobalt alloy material.

The solenoid is made of metal copper by vacuum electroplating. it is integrated and more stable in structure and more excellent in performance.

There is also a method of manufacturing a MEMS miniaturized solenoid transformer, comprising the steps:

Step 1, an upper silicon substrate and a low silicon substrate are fabricated;

Step 2, forming an upper core and a lower core by plating in the core slots of the upper silicon substrate and the lower silicon substrate, respectively;

Step 3, an upper surface of the upper silicon substrate and a lower surface of a lower silicon substrate are arranged opposite to each other, and a bottom surface of an upper iron core and an upper face of the lower iron core are aligned with each other. Bonding the upper silicon substrate and the lower silicon substrate with low temperature bonding processing, and forming the first spiral channel and the second spiral channel in the bonded upper and lower silicon substrates;

Step 4, The first solenoid and the second solenoid are formed by electroplating in the first spiral channel and the second spiral channel and obtains a MEMS solenoid transformer.

Step 1 also includes the step of: four pin slots are etched deeply in the silicon on the top surface of the first silicon wafer after the first oxidation according to the structures and locations of the four slots.

Step 4 also includes plating the four pins in the four pin slots.

The present invention discloses the following technical effects:

In this manufacture process, the two silicon substrate are separately manufactured, the iron core is electroplated before bonding, and a solenoid is electroplated to form the solenoid after bonding, the manufacturing process does not need to adopt deep etching of multi-layer silicon. The obtained transformer has high structure accuracy and is compatible with the IC semiconductor process, and is suitable for mass production; the upper and lower silicon substrates are bonded at low temperature. In order to ensure the bonding effect and prevent the plate solution from penetrating into the bonding surface during subsequent plate, the iron core and the integral solenoid are obtained by vacuum plating, and the structure is stronger, and the performance is better; By arranging the soft magnetic core of the transformer, the first solenoid, and the second solenoid all inside the silicon substrate, the thickness of the Si substrate is fully utilized. The resulting transformer has a larger winding cross-sectional area, high magnetic flux, high inductance value, is high work current and high total power. And the silicon substrate can protect the soft magnetic iron core, the first solenoid and the second solenoid, so the strength of the transformer can be improved, and the shock resistance performance is good; the micro solenoid transformer obtained by the invention can increase the number of turns without reducing the inductance density and the working efficiency; By skipping the step of electroplating iron core removing the silicon substrate of the micro-transformer, a substrate-free and iron-core-free transformer can be obtained. High dielectric strength materials such as polyimide, phenylpropylcyclobutene and the like are filled into the transformer, which can replace the planar transformer as the core transformer of the digital isolator.

BRIEF DESCRIPTION OF THE FIGURES

In order to more clearly illustrate that embodiments of the present application or the technical solution in the prior art, a brief description will be given below to the drawings that need to be used in the description of the embodiment or the prior art. it is obvious that, the drawings in the following description are some embodiments of the present application, and other drawings may also be obtained from these drawings without any creative effort by one of ordinary skill in the art.

FIG. 1 is a perspective structural diagram of a MEMS toroidal solenoid transformer in Embodiment 1;

FIG. 2 is a perspective structural diagram of an upper silicon substrate in Embodiment 1;

FIG. 3 is a perspective structural diagram of a lower silicon substrate in Embodiment 1;

FIG. 4 is a schematic diagram of the formation process of the upper silicon substrate and the lower silicon substrate of a MEMS toroidal solenoid transformer in Embodiment 1;

FIG. 5 is a schematic view of the manufacturing process of the upper core and is the lower core, the first spiral channel and the second spiral channel of the MEMS toroidal solenoid transformer according to Embodiment 1;

FIG. 6 is a schematic view of a manufacturing process of a first solenoid and a second solenoid of a MEMS toroidal solenoid transformer according to Embodiment 1;

FIG. 7 is a perspective structural diagram of a MEMS meander-shaped solenoid transformer according to Embodiment 2;

FIG. 8 is a perspective structural diagram of an upper silicon substrate in Embodiment 2;

FIG. 9 is a perspective structural diagram of a lower silicon substrate in Embodiment 2;

FIG. 10 is a three-dimensional structure diagram of a linear winding ironless solenoid transformer of the MEMS in Embodiment 3;

Reference signs:

1-silicon substrate; 2-ring soft magnet core;

2'- meander-shaped soft magnetic core 3 - first solenoid;

4-second solenoid; 5-pin;

5 '- pin slot; 11 - upper silicon substrate;

12 - lower silicon substrate; 21 - upper core;

22 - lower core; 31 '- first horizontal groove;

32 '- second horizontal groove; 33'- vertical hole.

DESCRIPTION OF THE INVENTION

In order to achieve the purpose, technical solution and advantages of the embodiments of the present application will be more clear, the technical solution in the embodiments will be clearly described in the following in conjunction with the is drawings, and it is obvious that, the described embodiments are part,of embodiments of the present application but not all. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of this application.

Example 1

Referring to figs. 1-3, an embodiment of the present application provides a MEMS toroidal solenoid transformer comprising a silicon substrate 1, a toroidal soft magnetic core 2, a first solenoid 3 and a second solenoid 4; Wherein, a ring-shaped soft magnetic core 2 is wrapped inside a silicon substrate 1 disposed with a first spiral channel and a second spiral channel, and two opposite sides of the ring-shaped soft magnetic core 2 pass through the center of the first helical channel and the centers of the second helical channel, respectively. The first solenoid 3 and the second solenoid 4 are disposed in a first helical channel and a second helical channel, respectively.

Wherein, since both the first spiral channel and the second spiral channel are disposed on the silicon substrate 1, the first solenoid 3 and the second solenoid 4 disposed in the first and second spiral cells, respectively, are also disposed inside the silicon substrate 1, that is, the toroidal soft magnetic core 2, the first solenoid 3 and the second solenoid 4 of the transformer are put inside the silicon substrate 1.

In the first solenoid 3 and the first spiral tunnel, the second solenoid 4 and the second spiral tunnel are the same in shape, and in each of the first and second spiral tunnels. As the two opposite sides of the ring-shaped soft magnetic core 2 pass through the center of the first helical channel and that of the second helical channel respectively, the two opposite sides of the annular soft magnetic core 2 also pass is through the centers of the first solenoid 3 and the second solenoid 4, respectively. When the transformer is in operation, the first solenoid 3 is the primary winding of the transformer, the second solenoid 4 is the secondary winding, and the leading and trailing ends of the first coil 3 form the input end. The leading and trailing ends of the second solenoid 4 constitute the output end of the transformer. It is to be understood that the number of turns of the first solenoid 3 and the second solenoid 4 determines the transformation ratio of the transformer.

The silicon substrate 1 is divided into an upper silicon substrate 11 and a lower silicon substrate 12, and the ring-shaped soft magnetic core 2 is divided between an upper core 21 and lower core 22, with the upper and lower cores 21 and 22 having the same shape;

The lower surface of the upper silicon substrate 11 is disposed with a core slot corresponding to the shape of an upper iron core 21, the upper surface of a lower silicon substrate 12 is disposed with core slots corresponding to a lower iron core 22. The upper core 21 and the lower core 22 are disposed in corresponding core slots, respectively, and a lower surface of the upper silicon substrate 11 and an upper surface of a lower silicon substrate 12 are bonded to each other ,so that the lower surfaces thereof are aligned with each other.

Here, the upper core 21 and the lower core 22 are two cores having the same shape, which are formed by bisecting the annular soft magnetic core 2 in the vertical direction, and are also annular in shape, and have a thickness of half that of the ring shaped soft magnetic iron core 2. The upper silicon substrate 11 and the lower silicon substrate 12 are formed by bisecting the silicon substrate 1 in the vertical direction, and are arranged symmetrically.

In that invention, the silicon substrate and the annular soft magnetic core are divide into two parts respectively, so that the whole of the transform is convenient to process. And at the same time, the eddy current loss in the core can be reduced, the efficiency of the transformer is further improved.

The first spiral channel and the second spiral channel respectively comprise a is plurality of first horizontal grooves 31 ', second horizontal grooves 32', and vertical holes 33 '.

A first horizontal trench 31'is disposed on the upper surface of the silicon substrate 1, a second horizontal trench 32 'is disposed on a lower surface of silicon substrate 2, and a vertical hole 33'is formed through the upper and lower surfaces;

The ends of any of the first and second spiral channels 31 "communicate with two vertical holes 33" respectively, and the two vertical though-holes 33'communicate with the two adjacent second horizontal channels 32 "respectively.

Here, when the silicon substrate 1 is divided into the upper silicon substrate 11 and the lower silicon substrate 12, each of the vertical holes 33'is also divided into two portions respectively located on the upper and lower silicon substrates 11 and 12.

In particular, in one spiral channel, that plurality of first horizontal grooves 31'and the plurality of second horizontal grooves 32 'communicate through a plurality of vertical holes 33'. It is to be understood that the vertical holes 33'may be linear or arc-shaped, and the first horizontal groove 31 'and the second horizontal groove 32' can be linear or arcuate.

The transformer also comprises four pins 5 and four pin slots 5

Four pin-grooves 5'are disposed on the upper surface of the silicon substrate 1, two of the four pin grooves 5 " communicating with the leading and trailing ends of the first spiral channel, respectively, the other two pin slots 5'of the four pin slots 5 'are in communication with the ends of the second spiral channel, respectively, and the four pins 5 are disposed in the respective four pin grooves 5'.

As two of the four pin slots 5' are in communication with the head-to-tail of the first spiral channel respectively and the other two pin slots 5 'in the four pins slots 5' also communicate with the heads and tails of the second spiral channel respectively, two of the four pins 5 are connected to the head-to-tail of the first solenoid tube 3, respectively, and the other two pins 5 among the four pin 5 are coupled to the end of the second solenoid tube 4, respectively. When the transformer is in operation, two of the four pins 5 form the input of the transformer, and the other two pins 5 of the 4 pins form the output.

The annular soft magnetic core 2 is made of iron-nickel alloy material or iron cobalt alloy material.

The first solenoid 3 and the second solenoid 4 are made of metallic copper.

Embodiments of the present application also provide a method of manufacturing a MEMS toroidal solenoid transformer, comprising the steps :

Step 1, forming an upper silicon substrate 11 and a lowersilicon substrate 12:

Fabricating the upper silicon substrate comprises performing a first thermal oxidation on a first silicon wafer of a first predetermined thickness according to the structures and relative positions of the first spiral channel and the second spiral channel, a plurality of first horizontal trenches 31'are etched deeply into the upper surface, the inner surface and the lower surface of the first silicon wafer after the first oxidation, respectively, and an upper half of the plurality of vertical holes and a core groove are etched. Performing a second thermal oxidation on the first silicon wafer after the deeply silicon etching to obtain a top silicon substrate;

Fabricating the lower silicon substrate comprises performing a first thermal oxidation on a second silicon wafer of a first predetermined thickness according to the structures and relative positions of the first spiral channel and the second spiral channel. The core slots, the lower halves of the vertical vias and the second horizontal trenches 32are etched deeply into the upper, inner and lower surfaces of the second silicon wafer after the first oxidation, respectively; the second wafer is subjected to a second thermal oxidation, Obtain the lower silicon substrate;

Step 2, forming an upper core 21 and a lower core 22 by plating in the core is slots of the upper silicon substrate 11 and the lower silicon substrate 12, specifically comprising:

After the metal mask with the pattern of core grooves is registered with the core grooves on the lower surface of the upper silicon substrate 11, the metal masking plate is closely attached to the lower surfaces of the top silicon substrates 11;

After magnetron-sputtering a second predetermined thickness of metallic nickel or metallic cobalt as a seed layer on the lower surface of the upper silicon substrate 11, the upper core 21 is obtained by plating a third predetermined depth of an iron-nickel alloy or iron-cobalt alloy in the iron-core slot.

After the metal mask with the pattern of core grooves is registered with the core grooves on the upper surface of the lower silicon substrate 12, the metal masking plate is closely attached to the upper surfaces of the bottom silicon substrates 12;

After magnetron sputtering a second predetermined thickness of metallic nickel or metallic cobalt as a seed layer on the upper surface of the lower silicon substrate 12, the lower core 22 is obtained by plating a third predetermined depth of an iron-nickel alloy or iron-cobalt alloy in the iron core slot of the bottom Si substrate 12.

Wherein, when the iron core uses the iron-nickel alloy, the corresponding seed layer uses metallic nickel, and when an iron-cobalt alloy is used, the matching seed layer adopts metallic cobalt. The thickness of the seed layer, i.e., the second predetermined thickness, may be determined according to actual process requirements. The thickness of the upper core 21 and the lower core 22 is the third preset thickness, which is determined according to the depth of the core slots.

Step 3, the upper surface of the upper silicon substrate 11 and the lower surface of lower silicon substrate 12 are arranged opposite to each other, and the upper and lower silicon substrates are low-temperature bonded after the lower surfaces of upper core 11 and lower core 11 are aligned with each other. Forming a first spiral channel and a second spiral channel in the bonded upper silicon substrate and lower silicon substrate;

Step 4, a first solenoid 3 and a second solenoid 4 are electroplate in the first helical channel and the second helical channel, resulting in a MEMS toroidal solenoid transform.

Magnetron sputtering a fourth predetermined thickness of titanium metal as an intermediate layer on the lower surface of the lower silicon substrate, and magnetron sputtering on the intermediate layer a fifth preset thickness of copper metal as a seed layer, plating metal copper in the second grooves and the vertical holes of the first and second spiral holes until the metal copper is filled to a position on the lower plane of the second groove;

After magnetron sputtering metallic copper as a seed layer on the upper surface of the upper silicon substrate, the metallic copper is electroplated until the first spiral channel and the second spiral channel are completely filled with metallic copper to obtain a first solenoid and a second solenoid.

In this embodiment, manufacturing the upper silicon substrate further comprises the steps:

According to the structure and location of the four slots, four pin slots are deeply etched in the top surface silicon of the first silicon wafer after the first oxidation; accordingly, in Step 4, four slots are plated in the four lead groove.

In the following, the manufacturing method of the MEMS toroidal solenoid transformer is further described through an example, and it should be noted that the following is only an example of the embodiment of the present application, and the embodiment is not limited thereto.

FIGS. 4-6 are schematic diagrams of a manufacturing process of a MEMS toroidal solenoid transformer disposed in Embodiment 1 of the present application, which are specifically as follows:

is (1) a 1000pm thick double-polishing silicon waf is used. High-resistivity silicon waf is adopted to improve insulate property of the whole structure and reducing eddy current loss under high frequency. The silicon wafer was thermally oxidized to form a 2pm thick thermal oxide layer on both sides.

(2)Coating the photoresist. Exposing a first horizontal trench (covering a position of a vertical via hole), a contact pattern on upper surface of upper silicon substrate; exposing vertical vias and a second horizontal trench on upper surface of low silicon substrate; exposing the core groove pattern, spiral channel includingthe first horizontal groove and the second horizontal groove and the vertical hole on lower surface of the upper silicon substrate and the lower silicon substrate respectively.

(3) Removing silicon dioxide at the exposed position using a BOE (Buffered Oxide Etch) solution, and patterning the silicon dioxide.

(4) Applying the glue for the second time, exposing the upper and lower surfaces of the upper silicon substrate and the lower silicon substrate to the vertical via pattern.

(5) Deeply etching the upper and lower surfaces of the silicon, and etching the through silicon via pattern to a certain depth.

(6) Removing the photoresist using a piranha solution.

(7) Etching the upper surface with the oxide layer as a masking layer, and etching the vertical via holes and the horizontal trenches on the top surface. The lower surface is etched with the oxide layer as a masking layer to etch the core pattern.

(8) by thermal oxidation, forming 2 pm thick oxide layer.

(9) Taking a metal mask plate with a core slot pattern, aligning the core slot patterns on the upper plate with those on the lower surface of the first silicon wafer and the second silicon wafer, and sticking to the lower surfaces of the silicon wafers.

(10) Taking 100 nm metallic nickel as a seed layer on the lower surface by magnetron sputtering.

(11) Electroplating the iron-nickel alloy from the bottom to a distance of 100 um from the surface of the silicon wafer.

(12) Carrying out low-temperature silicon-silicon bonding by opposing the lower surfaces of the upper silicon substrate and the lower silicon substrate.

(13) Taking magnetron sputtering of the lower surface with 100 nm titanium metal as an intermediate layer followed by 500 nm copper metal as a seed layer.

(14) Electroplating metallic copper so that the electroplated copper is filled from the bottom to the top horizontal conductor bottom planar position.

(15) Taking magnetron Sputtering of 500nm Copper on Surface.

(16) Plating the metallic copper so that the entire upper surface structure is completely covered by the plated copper.

(17) Copper on the upper and lower surfaces is thinned by CMP (chemical mechanical polishing machine) until copper is thinned to the same height as the silicon thermal oxide surface. Then the surface is polished by CMP to complete the fabrication of the micro-transformer for MEMS.

Example 2

Referring to figs. 7 to 9, a MEMS meander solenoid transformer is disposed, Comprising: A silicon substrate 1, a meander-shaped soft magnetic iron core 2, a first solenoid 3 and a second solenoid 4; its structural characteristics are described as in the MEMS solenoid toroidal transformer of embodiment 1, The only difference is that a meander-shaped soft magnetic core is used in this embodiment.

The manufacturing method is the same as in Example 1.

Example 3

Referring to fig. 10, providing a MEMS linear wound ironless solenoid transformer, comprising: A silicon substrate 1, a first solenoid 2, a second solenoid 3, and a pin 4; the description of its structural features is the same as that of the MEMS solenoid toroidal transformer of Embodiment 1, except that there is no soft magnetic core in this embodiment.

The present invention provides a MEMS solenoid inductor comprising at least three types of loop, toroidal, and straight wound ironless, as well as any other possible shapes and forms within the scope of this patent.

Finally, it should be noted that the above embodiments are only intended to illustrate the technical solution of the present application, and are not intended to limit the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that modifications may still be made to the technical solutions recited in the foregoing embodiments, or equivalent substitutions may be made for some of the technical features thereof; and such modifications or substitutions, the essence of the corresponding technical solution does not depart from the spirit and scope of the technical solution of the present application.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. In a MEMS solenoid transform comprising a silicon substrate, a soft magnetic iron core and a solenoid,

The soft magnetic core is wrapped inside the silicon substrate and passes through the center of a spiral channel disposed on the silicon substrates, and the solenoid is disposed in the spiral channel;

The silicon substrate comprises an upper silicon substrate and a lower silicon substrate, and the soft magnetic iron core comprises the upper iron core and the lower iron core having the same shape;

A lower surface of the upper silicon substrate is disposed with a core groove corresponding to the upper core shape, and an upper surface of a lower silicon substrate has a core slot corresponding to a shape of the lower core, The upper iron core and the lower iron core are respectively arranged in corresponding iron core slots, and a lower surface of the upper silicon substrate and an upper face of the is lower silicon substrate are bonded to each other;

The spiral channel comprises a plurality of first horizontal grooves, a plurality of second horizontal grooves and a plurality of the vertical holes, the first horizontal groove being arranged on the upper surface of the silicon substrate, the second horizontal trench is disposed on the lower surface of the silicon substrate, and the vertical hole passes through the upper and lower surfaces thereof, and any of the first horizontal trenches communicates with two vertical holes, respectively. The two vertical holes are respectively communicated with two adjacent second horizontal trenches;

A solenoid includes a first solenoid and a second solenoid, the first solenoid being disposed in the first helical bore, and the second solenoid being positioned in the second helical bore.

2. The MEMS solenoid transformer according to claim 1, characterized in that the upper iron core and the lower iron core are formed by plating in iron core slots of the upper silicon substrate and lower silicon substrate.

3. The MEMS solenoid transformer according to claim 1, characterized in that the upper silicon substrate and the lower silicon substrate are bonded with low temperature bonding technology, and the spiral channel is formed in the bonded upper and lower silicon substrates.

4. The MEMS solenoid transformer according to claim 1, characterized in that it further comprises four pins and four pin slots;

The four pin grooves are arranged on the upper surface of the silicon substrate, and two pin grooves of the four pins grooves are respectively communicated with the head and tail of the first spiral channel, The other two pin grooves of the four

pin grooves are respectively communicated with the head and tail of the second spiral channel, and the four pins are respectively arranged in the four pin slots

. is

5. The MEMS solenoid transformer according to claim 1, characterized in that the soft magnetic iron core is made of an iron nickel alloy material or an iron cobalt alloy material.

6. According to claim 1, the MEMS solenoid transformer is characterized in that the first solenoid and the second solenoid are made of metal copper.

7.A method for manufacturing a MEMS toroidal solenoid transformer according to any one of claims 1 to 6, characterized in that it comprises:

Step 1, an upper silicon substrate and a low silicon substrate are fabricated;

Step 2, forming an upper core and a lower core by vacuum plating in the core slots of the upper silicon substrate and the lower silicon substrate, respectively;

Step 3, an upper surface of the upper silicon substrate and a lower surface of a lower silicon substrate are arranged opposite to each other, and a bottom surface of an upper iron core and an upper face of the lower iron core are aligned with each other. Bonding the upper silicon substrate and the lower silicon substrate with low temperature bonding, and forming the first spiral channel and the second spiral channel in the bonded upper and lower silicon substrates;

Step 4, a first solenoid and a second solenoid are electroplate in that first helical channel and the second helical channel to obtain a MEMS toroidal solenoid transformer.

8. In accordance with claim 7, that method is characterized in that step 1 which further comprises:

According to the structures and locations of the four slots, four pin slots are etched deeply in the silicon of the upper surface of the first silicon wafer after the first oxidation.

9. In accordance with claim 7, that method is characterize in that the step 4 further comprises vacuum plate forming the four pins in the four pin grooves.