CN109599249B - MEMS (micro-electromechanical system) loop solenoid transformer and manufacturing method thereof - Google Patents

Abstract

An embodiment of the present invention provides a MEMS looped solenoid transformer, comprising: a silicon substrate, a looped soft magnetic core, a first solenoid and a second solenoid; wherein the looped soft magnetic core is wrapped in silicon Inside the substrate, a first spiral channel and a second spiral channel are arranged on the silicon substrate, and the two opposite sides of the soft magnetic core of the meander pass through the center of the first spiral channel and the center of the second spiral channel, respectively. A solenoid and a second solenoid are respectively arranged in the first spiral channel and the second spiral channel. 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 silicon substrate is fully utilized, and the resulting transformer has a larger winding cross-sectional area. The magnetic flux is higher, which makes the inductance value of the transformer high; at the same time, the silicon substrate can protect the soft magnetic core, the first solenoid and the second solenoid, which improves the strength of the transformer and has good impact resistance. .

Description

A kind of MEMS loop solenoid transformer and its manufacturing method

technical field

Embodiments of the present invention relate to the technical field of micro-electromechanical systems (MEMS), and more particularly, to a MEMS looped solenoid transformer and a method for manufacturing the same.

Background technique

The Micro-Electro-Mechanical System (MEMS) micro-transformer uses the principle of electromagnetic induction to transfer electrical energy between two circuits. It is composed of a magnetic core and a winding. The format has also changed. Micro-transformers are widely used in micro-electronic equipment and information equipment, and can play the roles of voltage transformation, current transformation, impedance transformation, isolation, and voltage regulation.

At present, the micro-transformers based on MEMS technology are mainly divided into two types, planar spiral type and solenoid type. Among them, the structure of the planar spiral transformer increases with the number of winding turns and the diameter of the coil becomes larger, and the total magnetic flux along the iron core does not increase linearly but gradually decreases. Therefore, the number of turns of this structure is generally limited, which leads to this There is a bottleneck in the total power improvement of the transformer. Solenoid transformers overcome the limitation of the number of winding turns and in principle can further increase the total power of the transformer.

However, at present, most of the micro-transformers based on the MEMS process use the thin-film manufacturing process. The thin-film manufacturing process is an additive manufacturing method. Therefore, most of the structures of the obtained micro-transformers are on the substrate, which makes it difficult to guarantee the strength of the transformer. , the impact resistance is poor; at the same time, the vertical height that can be obtained by the thin film manufacturing process is limited, so that the cross-sectional area of the transformer winding is small, resulting in a low inductance value and a small magnetic flux of the transformer.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a MEMS looped solenoid transformer and a manufacturing method thereof that overcome the above problems or at least partially solve the above problems.

In one aspect, an embodiment of the present invention provides a MEMS looped solenoid transformer, including: a silicon substrate, a looped soft magnetic core, a first solenoid, and a second solenoid; wherein,

The loop-shaped soft magnetic core is wrapped inside the silicon substrate, the silicon substrate is provided with a first spiral channel and a second spiral channel, and the two opposite sides of the loop-shaped soft magnetic core pass through respectively. Through the center of the first spiral channel and the center of the second spiral channel, the first solenoid and the second solenoid are respectively arranged in the first spiral channel and the second spiral channel middle.

Further, the silicon substrate is divided into an upper silicon substrate and a lower silicon substrate, the meander-shaped soft magnetic core is divided into an upper iron core and a lower iron core, and the shape of the upper iron core and the lower iron core is same;

The lower surface of the upper silicon substrate is provided with an iron core groove corresponding to the shape of the upper iron core, and the upper surface of the lower silicon substrate is provided with an iron core groove corresponding to the shape of the lower iron core, The upper iron core and the lower iron core are respectively arranged in the corresponding iron core slots, and the lower surface of the upper silicon substrate and the upper surface of the lower silicon substrate are bonded to each other, so that the upper iron core is The lower surface of the core and the upper surface of the lower iron core are aligned with each other.

Further, the first spiral channel and the second spiral channel respectively comprise a plurality of first horizontal grooves, a plurality of second horizontal grooves and a plurality of vertical through holes;

The first horizontal trench is arranged on the upper surface of the silicon substrate, the second horizontal trench is arranged on the lower surface of the silicon substrate, and the vertical through hole penetrates through the upper surface of the silicon substrate surface and subsurface;

The head and tail of any one of the first horizontal grooves in the first spiral channel and the second spiral channel are respectively communicated with two vertical through holes, and the two vertical through holes are respectively connected with two vertical through holes. The adjacent second horizontal grooves communicate with each other.

Further, it also includes four pins and four pin slots;

The four lead grooves are arranged on the upper surface of the silicon substrate, two lead grooves in the four lead grooves are respectively connected with the head and tail of the first spiral channel, and the four lead grooves The other two pin slots in the slot are respectively communicated with the head and tail of the second helical channel, and the four pins are respectively arranged in the four pin slots.

Further, the meander-shaped soft magnetic core is made of iron-nickel alloy material or iron-cobalt alloy material.

Further, the first solenoid and the second solenoid are made of metal copper.

On the other hand, an embodiment of the present invention provides a method for manufacturing a MEMS looped solenoid transformer, including:

Step 1, respectively fabricating an upper silicon substrate and a lower silicon substrate; wherein,

Making the upper silicon substrate includes:

performing the first thermal oxidation on the first silicon wafer with the first preset thickness;

According to the structures and relative positions of the first spiral channel and the second spiral channel, a plurality of parallel first horizontal lines are etched into the upper surface, the inner surface and the lower surface of the first silicon wafer after the first oxidation respectively. a groove, an upper half of a plurality of vertical through holes, and a core slot;

The second thermal oxidation is performed on the first silicon wafer obtained by deep silicon etching to obtain the upper silicon substrate;

Making the lower silicon substrate includes:

performing the first thermal oxidation on the second silicon wafer of the first preset thickness;

According to the structures and relative positions of the first spiral channel and the second spiral channel, core grooves, a plurality of vertical silicon wafers are etched into the upper surface, the inner surface and the lower surface of the second silicon wafer after the first oxidation, respectively. the lower half of the through hole and a plurality of parallel second horizontal grooves;

performing a second thermal oxidation on the second silicon wafer to obtain the lower silicon substrate;

Step 2, forming an upper iron core and a lower iron core by electroplating in the iron core grooves of the upper silicon substrate and the lower silicon substrate respectively;

In step 3, the upper surface of the upper silicon substrate and the lower surface of the lower silicon substrate are arranged opposite each other, and after the lower surface of the upper iron core and the upper surface of the lower iron core are aligned with each other, The upper silicon substrate and the lower silicon substrate are bonded at low temperature, and the first spiral channel and the second spiral channel are formed in the bonded upper silicon substrate and the lower silicon substrate ;

In step 4, a first solenoid and a second solenoid are formed by electroplating in the first spiral channel and the second spiral channel, that is, a MEMS loop solenoid transformer is obtained.

Further, forming the upper iron core by electroplating in the iron core groove of the upper silicon substrate specifically includes:

After the metal mask with the iron core groove pattern is registered with the iron core groove on the lower surface of the upper silicon substrate, the metal mask is closely attached to the lower surface of the upper silicon substrate ;

After the lower surface of the upper silicon substrate is magnetron sputtered with a second preset thickness of metal nickel or metal cobalt as a seed layer, iron-nickel with a third preset thickness is electroplated in the iron core groove of the upper silicon substrate Alloy or iron-cobalt alloy to get the upper iron core; accordingly,

The forming of the lower iron core by electroplating in the iron core groove of the lower silicon substrate specifically includes:

After the metal mask with the iron core groove pattern is registered with the iron core groove on the upper surface of the lower silicon substrate, the metal mask is closely attached to the upper surface of the lower silicon substrate ;

After the upper surface of the lower silicon substrate is magnetron sputtered with a second preset thickness of metal nickel or metal cobalt as a seed layer, iron-nickel with a third preset thickness is electroplated in the iron core groove of the lower silicon substrate Alloy or iron-cobalt alloy to get the lower core.

Further, forming the first solenoid and the second solenoid by electroplating in the first spiral channel and the second spiral channel specifically includes:

On the lower surface of the lower silicon substrate, magnetron sputtering metal titanium with a fourth preset thickness is used as an intermediate layer, and magnetron sputtering metal copper with a fifth preset thickness is used as a seed layer on the intermediate layer. Electroplating metal copper in the first spiral channel and the second trench and vertical through hole of the second spiral channel until the metal copper is filled to the position of the lower plane of the first channel;

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

Further, the manufacturing of the upper silicon substrate includes further comprising:

According to the structure and position of the four pins, four pin grooves are deeply etched on the upper surface of the first silicon wafer after the first oxidation; accordingly,

Also included in step 4:

The four pins are formed by electroplating in the four pin slots.

The embodiment of the present invention provides a MEMS looped solenoid transformer and a manufacturing method thereof. By making full use of the thickness of the silicon substrate, the obtained transformer has a larger winding cross-sectional area and a higher magnetic flux, so that the inductance value of the transformer is high; The second solenoid plays a protective role, improves the strength of the transformer, and has good impact resistance.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1 is a schematic three-dimensional structure diagram of a MEMS loop solenoid transformer provided by an embodiment of the present invention;

FIG. 2 is a schematic three-dimensional structure diagram of an upper silicon substrate in an embodiment of the present invention;

3 is a schematic three-dimensional structure diagram of a lower silicon substrate in an embodiment of the present invention;

4 is a schematic cross-sectional view of steps (1) to (6) of a manufacturing process of a MEMS loop solenoid transformer in an example provided by an embodiment of the present invention;

5 is a schematic cross-sectional view of steps (7) to (12) of a manufacturing process of a MEMS loop solenoid transformer in an example provided by an embodiment of the present invention;

6 is a schematic cross-sectional view of steps (13) to (17) of a manufacturing process of a MEMS loop solenoid transformer in an example provided by an embodiment of the present invention;

Reference number:

1-silicon substrate; 2-reflex soft magnetic core;

3-first solenoid; 4-second solenoid;

5-pin; 5'-pin slot;

11-upper silicon substrate; 12-lower silicon substrate;

21-upper iron core; 22-lower iron core;

31'-the first horizontal groove; 32'-the second horizontal groove;

33' - Vertical through hole.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are the Some, but not all, embodiments are disclosed. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

FIG. 1 is a schematic three-dimensional structural diagram of a MEMS looped solenoid transformer provided by an embodiment of the present invention. As shown in FIG. 1 , it includes: a silicon substrate 1 , a looped soft magnetic core 2 , a first solenoid 3 and The second solenoid 4; wherein,

The meander-shaped soft magnetic core 2 is wrapped inside the silicon substrate 1 , as shown in FIG. 2 and FIG. 3 , the silicon substrate 1 is provided with a first spiral channel and a second spiral channel, and the back The two opposite sides of the soft magnetic core 2 respectively pass through the center of the first spiral channel and the center of the second spiral channel, the first solenoid 3 and the second solenoid 4 respectively arranged in the first spiral channel and the second spiral channel.

Among them, since the first spiral channel and the second spiral channel are both arranged on the silicon substrate 1, the first solenoid 3 and the second solenoid 4 respectively arranged in the first spiral channel and the second spiral channel are also They are arranged inside the silicon substrate 1 , that is, the meander-shaped soft magnetic core 2 of the transformer, the first solenoid 3 and the second solenoid 4 are all arranged inside the silicon substrate 1 .

Specifically, the shape of the first solenoid 3 and the first spiral hole are the same, the shape of the second solenoid 4 and the second spiral hole are the same, and the first solenoid 3 and the second solenoid 4 are respectively arranged in the first solenoid In the spiral channel and the second spiral channel, since the two opposite sides of the soft magnetic core 2 pass through the center of the first spiral channel and the center of the second spiral channel respectively, the two opposite sides of the soft magnetic core 2 The sides also pass through the centers of the first solenoid 3 and the second solenoid 4, respectively. When the transformer is working, the first solenoid 3 is the primary winding of the transformer, the second solenoid 4 is the secondary winding of the transformer, the first and last ends of the first solenoid 3 constitute the input end of the transformer, and the second solenoid The first and last ends of 4 constitute the output end of the transformer. It can 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 embodiment of the present invention provides a MEMS looped solenoid transformer. By arranging the looped soft magnetic core, the first solenoid and the second solenoid of the transformer inside the silicon substrate, the silicon substrate is fully utilized. The thickness of the substrate, the resulting transformer has a larger winding cross-sectional area and a higher magnetic flux, so that the inductance value of the transformer is high; at the same time, the silicon substrate can be used for the soft magnetic core, the first solenoid and the second solenoid. The tube plays a protective role, improves the strength of the transformer, and has good impact resistance.

In the above embodiment, as shown in FIGS. 1-3 , the silicon substrate 1 is divided into an upper silicon substrate 11 and a lower silicon substrate 12 , and the soft ring-shaped magnetic core 2 is divided into an upper iron core 21 and a lower silicon substrate 12 . The iron core 22, and the upper iron core 21 and the lower iron core 22 have the same shape;

The lower surface of the upper silicon substrate 11 is provided with an iron core groove corresponding to the shape of the upper iron core 21 , and the upper surface of the lower silicon substrate 12 is provided with an iron core groove corresponding to the shape of the lower iron core 22 . Iron core slots, the upper iron core 21 and the lower iron core 22 are respectively disposed in the corresponding iron core slots, and the lower surface of the upper silicon substrate 11 and the upper surface of the lower silicon substrate 12 are mutually bonding, so that the lower surface of the upper iron core 21 and the upper surface of the lower iron core 22 are aligned with each other.

Among them, the upper iron core 21 and the lower iron core 22 are two iron cores with the same shape, which are bisected by the soft magnetic core 2 in the vertical direction. half of the core 2. Similarly, the upper silicon substrate 11 and the lower silicon substrate 12 are formed by bisecting the silicon substrate 1 in the vertical direction, and the two are symmetrically arranged.

By dividing the silicon substrate and the soft magnetic core into two parts, the transformer as a whole is easy to process. At the same time, the soft magnetic core is divided into two parts: the upper iron core and the lower iron core. Eddy current losses further improve the efficiency of the transformer.

In the above embodiment, as shown in FIG. 2 and FIG. 3 , the first spiral channel and the second spiral channel respectively include a plurality of first horizontal grooves 31 ′, a plurality of second horizontal grooves 32 ′ and a plurality of vertical through holes 33';

The first horizontal trenches 31 ′ are arranged on the upper surface of the silicon substrate 1 , the second horizontal trenches 32 ′ are arranged on the lower surface of the silicon substrate 1 , and the vertical through holes 33 ′ are arranged on the lower surface of the silicon substrate 1 . passing through the upper surface and the lower surface of the silicon substrate;

The head and tail of any one of the first horizontal grooves 31 ′ in the first spiral channel and the second spiral channel are respectively communicated with two vertical through holes 33 ′, and the two vertical through holes 33 ' respectively communicate with two adjacent second horizontal grooves 32'.

Wherein, when the silicon substrate 1 is divided into an upper silicon substrate 11 and a lower silicon substrate 12 , each vertical via 33 ′ is also divided into two parts located on the upper silicon substrate 11 and the lower silicon substrate 12 respectively. part.

Specifically, in a spiral channel, a plurality of first horizontal grooves 31' are arranged parallel to each other, and a plurality of second horizontal grooves 32' are also arranged parallel to each other, and are communicated through a plurality of vertical through holes 33'. It can be understood that the vertical through hole 33' may be linear or arc-shaped, and the first horizontal groove 31' and the second horizontal groove 32' may also be linear or arc-shaped.

In the above-mentioned embodiment, as shown in Figure 1, the transformer also includes four pins 5 and four pin slots 5';

The four lead grooves 5' are arranged on the upper surface of the silicon substrate 1, and the two lead grooves 5' in the four lead grooves 5' are respectively connected with the head and tail of the first spiral channel. , the other two pin slots 5' in the four pin slots 5' are respectively connected with the head and tail of the second spiral channel, and the four pins 5 are respectively arranged in the four pin slots 5 'middle.

Specifically, since two of the four lead slots 5' are connected to the first and last spiral holes respectively, the other two of the four lead slots 5' are respectively connected to the first and last spiral holes The head and tail of the two-spiral channel are connected, so two of the four pins 5 are connected to the head and tail of the first solenoid 3 respectively, and the other two pins 5 of the four pins 5 are respectively connected to the second End-to-end connection of solenoid 4. When the transformer is working, two of the four pins 5 constitute the input end of the transformer, and the other two pins 5 of the four pins 5 constitute the output end of the transformer.

In the above-mentioned embodiment, the meander-shaped soft magnetic core 2 is made of iron-nickel alloy material or iron-cobalt alloy material.

In the above embodiment, the first solenoid 3 and the second solenoid 4 are made of metal copper.

A method for manufacturing a MEMS loop solenoid transformer provided by an embodiment of the present invention includes:

Step 1, respectively fabricating an upper silicon substrate and a lower silicon substrate; wherein, fabricating the upper silicon substrate includes: performing a first thermal oxidation on a first silicon wafer with a first preset thickness; For the structure and relative position of the second spiral channel, a plurality of parallel first horizontal trenches, a plurality of vertical grooves, a plurality of parallel first horizontal grooves, a plurality of vertical silicon grooves are formed on the upper surface, the inner surface and the lower surface of the first silicon wafer after the first oxidation, respectively. the upper half of the through hole and the iron core groove; the second thermal oxidation is performed on the first silicon wafer obtained by deep silicon etching to obtain the upper silicon substrate; the manufacturing of the lower silicon substrate includes: The second silicon wafer with the first preset thickness is subjected to the first thermal oxidation; according to the structures and relative positions of the first spiral channel and the second spiral channel, respectively on the second silicon wafer after the first oxidation The iron core groove, the lower half of a plurality of vertical through holes and a plurality of parallel second horizontal grooves are deeply etched from the surface, the inner and the lower surface of the silicon; the second thermal oxidation is performed on the second silicon wafer to obtain the lower silicon substrate;

Step 2, forming an upper iron core and a lower iron core by electroplating in the iron core grooves of the upper silicon substrate and the lower silicon substrate respectively;

In step 3, the upper surface of the upper silicon substrate and the lower surface of the lower silicon substrate are arranged opposite each other, and after the lower surface of the upper iron core and the upper surface of the upper iron core are aligned with each other, The upper silicon substrate and the lower silicon substrate are bonded at low temperature, and the first spiral channel and the second spiral channel are formed in the bonded upper silicon substrate and the lower silicon substrate ;

In step 4, a first solenoid and a second solenoid are formed by electroplating in the first spiral channel and the second spiral channel, that is, a MEMS loop solenoid transformer is obtained.

Wherein, in step 1, the difference in structure between the upper silicon substrate 11 and the lower silicon substrate 12 is substantially only in that the upper surface of the upper silicon substrate 11 is provided with the first horizontal trench 31 ′, and the lower silicon substrate A second horizontal trench 32 ′ is provided on the lower surface of the bottom 12 , and the rest of the structure is the same. The silicon substrate 11 and the lower silicon substrate 12 are symmetrically arranged, and the processing process before the bonding of the two is basically the same.

In step 2, the upper iron core 21 and the lower iron core 22 are formed by electroplating on the upper silicon substrate 11 and the lower silicon substrate 12 respectively. A step is completed before bonding the upper silicon substrate 11 and the lower silicon substrate 12 .

In step 3, when bonding the upper silicon substrate 11 and the lower silicon substrate 12, it is necessary to ensure that the lower surface of the upper iron core 21 and the upper surface of the lower iron core 22 are aligned with each other to ensure that the magnetic fields of the two are mutually aligned. coordination. At the same time, after the upper silicon substrate 11 and the lower silicon substrate 12 are bonded, the horizontal trenches and vertical through holes previously provided on the upper silicon substrate 11 and the lower silicon substrate 12 are combined to form the first spiral channel and the The second spiral channel.

In step 4, after the first spiral channel and the second spiral channel are formed, the first solenoid 3 and the second solenoid 4 only need to be plated with relevant metals therein.

Specifically, the first silicon wafer and the second silicon wafer can be double-polished silicon wafers with a thickness of 1000 μm, and silicon wafers with high resistivity can be used to improve the overall insulation of the transformer and reduce the eddy current loss at high frequencies. Thermal oxidation of the first silicon wafer and the second silicon wafer is generally sufficient to form a thermal oxide layer with a thickness of 2 μm. According to the structures and relative positions of the meander-shaped soft magnetic core 2, the first spiral channel 3 and the second spiral channel 4, the first silicon wafer and the second silicon wafer are deeply etched to obtain the upper silicon substrate 11 and the lower silicon substrate 12 and thermal oxidation treatment is performed here, and the upper silicon substrate 11 and the lower silicon substrate 12 can be used as bases for making other structures of the transformer. Next, the upper iron core 21 and the lower iron core 22 are formed by electroplating at the corresponding positions of the upper silicon substrate 11 and the lower silicon substrate 12 . The upper iron core 21 and the lower iron core 22 are wrapped inside the silicon substrate 1 by bonding, and a complete first spiral channel and the second spiral channel are formed. The first solenoid 3 and the second solenoid 4 are formed by electroplating in the first spiral channel and the second spiral channel, and the fabrication of the MEMS loop solenoid transformer is completed.

The embodiment of the present invention provides a method for manufacturing a MEMS looped solenoid transformer. The silicon substrate is divided into two symmetrical parts to be manufactured separately, and the iron core is electroplated before re-bonding. Line tube, the whole production process does not need to use multi-layer silicon deep etching, which improves the fault tolerance rate of processing, has good repeatability, and the obtained transformer structure has high accuracy and is compatible with IC semiconductor technology, which is suitable for mass production. .

In the above embodiment, the formation of the upper iron core 21 by electroplating in the iron core groove of the upper silicon substrate 11 specifically includes:

After the metal mask with the iron core groove pattern is registered with the iron core groove on the lower surface of the upper silicon substrate 11, the metal mask is closely attached to the upper silicon substrate 11. lower surface;

After the lower surface of the upper silicon substrate 11 is magnetron sputtered with a second preset thickness of metal nickel or metal cobalt as a seed layer, electroplating of a third preset thickness of metal nickel or metal cobalt is performed in the iron core groove of the upper silicon substrate 11 The upper iron core 21 is obtained by iron-nickel alloy or iron-cobalt alloy.

Correspondingly, forming the lower iron core 22 by electroplating in the iron core groove of the lower silicon substrate 12 specifically includes:

After the metal mask with the iron core groove pattern is registered with the iron core groove on the upper surface of the lower silicon substrate 12, the metal mask is closely attached to the lower silicon substrate 12. upper surface;

After the upper surface of the lower silicon substrate 12 is magnetron sputtered with a second predetermined thickness of metal nickel or metal cobalt as a seed layer, electroplating of a third predetermined thickness of metal nickel or metal cobalt is performed in the iron core groove of the lower silicon substrate 12 The lower iron core 22 is obtained by iron-nickel alloy or iron-cobalt alloy.

Wherein, when the iron core is made of iron-nickel alloy, the corresponding seed layer is made of metal nickel; when the iron core is made of iron-cobalt alloy, the corresponding seed layer is made of metal cobalt. The thickness of the seed layer, that is, the second preset thickness, can be determined according to actual process requirements. The thicknesses of the upper iron core 21 and the lower iron core 22 , that is, the third preset thickness, are determined according to the depth of the iron core slots.

Specifically, the manufacturing process of the upper iron core 21 and the lower iron core 22 adopts the same process, except that the two are formed at different positions, and the two can be separately processed and manufactured at the same time.

In the above embodiment, the electroplating to form the first solenoid 3 and the second solenoid 4 in the first spiral channel and the second spiral channel specifically includes:

On the lower surface of the lower silicon substrate, magnetron sputtering metal titanium with a fourth preset thickness is used as an intermediate layer, and magnetron sputtering metal copper with a fifth preset thickness is used as a seed layer on the intermediate layer. Electroplating metal copper in the first spiral channel and the second trench and vertical through hole of the second spiral channel until the metal copper is filled to the position of the lower plane of the first channel;

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

In the above embodiment, the manufacturing of the upper silicon substrate includes further comprising:

According to the structure and position of the four pins, four pin grooves are deeply etched on the upper surface of the first silicon wafer after the first oxidation;

Correspondingly, step 4 also includes:

The four pins are formed by electroplating in the four pin slots.

The manufacturing method of the MEMS loop solenoid transformer is further described below through an example. It should be noted that the following is only an example of the embodiment of the present invention, and the embodiment of the present invention is not limited thereto.

4-6 are schematic cross-sectional views of steps (1) to (17) of a manufacturing process of a MEMS loop solenoid transformer in an example provided by an embodiment of the present invention, specifically:

(1) 1000μm thick double-polished silicon wafer is used. High resistivity silicon wafers are used to improve the overall structural insulation and reduce eddy current losses at high frequencies. The silicon wafer is thermally oxidized to generate a thermal oxide layer with a thickness of 2 μm on both sides.

(2) Coating photoresist, exposing the upper surface of the upper silicon substrate to the first horizontal trench (covering the position of the vertical via) and the contact pattern, and exposing the upper surface of the lower silicon substrate to the vertical via and the second horizontal trench grooves, the lower surfaces of the upper silicon substrate and the lower silicon substrate expose the iron core groove patterns respectively, and the first horizontal groove, the second horizontal groove and the vertical through hole form a spiral channel.

(3) Use BOE (Buffered Oxide Etch) solution to remove the silicon dioxide at the exposed position and pattern.

(4) The second application of glue, the upper and lower surfaces of the upper silicon substrate and the lower silicon substrate are exposed to vertical through hole patterns.

(5) The upper and lower surfaces of the silicon are deeply etched, and the through-silicon hole pattern is etched

(6) Use piranha solution to remove photoresist

(7) The upper surface is etched with the oxide layer as a masking layer, and vertical through holes and horizontal grooves on the upper surface are etched. The lower surface is etched with the oxide layer as a masking layer, and the iron core pattern is etched.

(8) Thermal oxidation to form a 2 μm thick oxide layer.

(9) Take a metal mask with an iron core groove pattern, align the iron core groove pattern on the upper iron core groove pattern with the iron core groove pattern on the lower surface of the No. 1 and No. 2 silicon wafers, and stick closely to the lower surface of the silicon wafer.

(10) The lower surface is magnetron sputtered with 100 nm metal nickel as the seed layer.

(11) Electroplating iron-nickel alloy, so that the iron-nickel alloy is filled from the bottom to 100um from the surface of the silicon wafer.

(12) The lower surfaces of the upper silicon substrate and the lower silicon substrate are opposed to each other, and low-temperature silicon-silicon bonding is performed.

(13) Magnetron sputtering of 100 nm metal titanium on the lower surface as an intermediate layer, followed by sputtering of 500 nm metal copper as a seed layer.

(14) Electroplating metal copper so that the electroplating copper is filled from the bottom to the lower plane position of the top horizontal wire.

(15) Magnetron sputtering 500nm metal copper on the upper surface.

(16) Electroplating metal copper, so that the entire structure of the upper surface is completely covered by electroplating copper.

(17) Use CMP (chemical mechanical polisher) to thin the metal copper on the upper and lower surfaces until the metal copper is thinned to the same height as the surface of the thermal oxide layer of the silicon wafer, and then CMP polishes the surface to complete the fabrication of the MEMS microtransformer.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be The technical solutions described in the foregoing embodiments are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (7)

1. A MEMS loop solenoid transformer, comprising: the solenoid coil comprises a silicon substrate, a clip-shaped soft magnetic iron core, a first solenoid and a second solenoid; wherein,

the square soft magnetic iron core is wrapped inside the silicon substrate, a first spiral pore passage and a second spiral pore passage are arranged on the silicon substrate, two opposite edges of the square soft magnetic iron core respectively penetrate through the center of the first spiral pore passage and the center of the second spiral pore passage, and the first solenoid and the second solenoid are respectively arranged in the first spiral pore passage and the second spiral pore passage;

the silicon substrate is divided into an upper silicon substrate and a lower silicon substrate, the square soft magnetic iron core is divided into an upper iron core and a lower iron core, and the upper iron core and the lower iron core are identical in shape;

the lower surface of the upper silicon substrate is provided with iron core grooves corresponding to the upper iron core in shape, the upper surface of the lower silicon substrate is provided with iron core grooves corresponding to the lower iron core in shape, the upper iron core and the lower iron core are respectively arranged in the corresponding iron core grooves, and the lower surface of the upper silicon substrate and the upper surface of the lower silicon substrate are mutually bonded, so that the lower surface of the upper iron core and the upper surface of the lower iron core are mutually aligned;

the upper iron core and the lower iron core are formed by electroplating in iron core grooves of the upper silicon substrate and the lower silicon substrate;

the first spiral duct and the second spiral duct respectively comprise a plurality of first horizontal grooves, a plurality of second horizontal grooves and a plurality of vertical through holes;

the first horizontal groove is arranged on the upper surface of the silicon substrate, the second horizontal groove is arranged on the lower surface of the silicon substrate, and the vertical through hole penetrates through the upper surface and the lower surface of the silicon substrate;

the head and the tail of any one first horizontal groove in the first spiral pore channel and the second spiral pore channel are respectively communicated with two vertical through holes, and the two vertical through holes are respectively communicated with two adjacent second horizontal grooves;

performing magnetron sputtering on the lower surface of the lower silicon substrate to obtain metal titanium with a fourth preset thickness as an intermediate layer, performing magnetron sputtering on the intermediate layer to obtain metal copper with a fifth preset thickness as a seed layer, and electroplating the metal copper in the second grooves and the vertical through holes of the first spiral pore passage and the second spiral pore passage until the metal copper is filled to the position of the lower plane of the first groove;

and after the upper surface of the upper silicon substrate is subjected to magnetron sputtering of metal copper as a seed layer, electroplating the metal copper until the first spiral pore canal and the second spiral pore canal are completely filled with the metal copper, and thus obtaining the first solenoid and the second solenoid.

2. The MEMS solenoid transformer of claim 1, further comprising four pins and four pin slots;

the four pin grooves are arranged on the upper surface of the silicon substrate, two of the four pin grooves are respectively communicated with the head and the tail of the first spiral pore passage, the other two of the four pin grooves are respectively communicated with the head and the tail of the second spiral pore passage, and the four pins are respectively arranged in the four pin grooves.

3. The MEMS solenoid transformer of claim 1, wherein the soft magnetic toroid is made of an iron-nickel alloy material or an iron-cobalt alloy material.

4. The MEMS solenoid transformer of claim 1, wherein the first and second solenoids are made of metallic copper.

5. A method of manufacturing a MEMS toroidal solenoid transformer as claimed in any one of claims 1 to 4, comprising:

step 1, respectively manufacturing an upper silicon substrate and a lower silicon substrate; wherein,

the manufacturing of the upper silicon substrate comprises the following steps:

carrying out first thermal oxidation on a first silicon wafer with a first preset thickness;

according to the structures and relative positions of the first spiral pore canal and the second spiral pore canal, a plurality of parallel first horizontal grooves, upper half parts of a plurality of vertical through holes and iron core grooves are respectively etched in the silicon on the upper surface, the interior and the lower surface of the first silicon wafer after the first oxidation;

carrying out second thermal oxidation on the first silicon wafer obtained by silicon deep etching to obtain the upper silicon substrate;

fabricating the lower silicon substrate includes:

carrying out first thermal oxidation on a second silicon wafer with a first preset thickness;

according to the structures and relative positions of the first spiral pore canal and the second spiral pore canal, iron core grooves, the lower half parts of a plurality of vertical through holes and a plurality of parallel second horizontal grooves are respectively etched in the silicon on the upper surface, the interior and the lower surface of the second silicon wafer after the first oxidation;

performing second thermal oxidation on the second silicon wafer to obtain the lower silicon substrate;

step 2, respectively electroplating the iron core grooves of the upper silicon substrate and the lower silicon substrate to form an upper iron core and a lower iron core;

step 3, oppositely arranging the upper surface of the upper silicon substrate and the lower surface of the lower silicon substrate, aligning the lower surface of the upper iron core and the upper surface of the lower iron core, bonding the upper silicon substrate and the lower silicon substrate at a low temperature, and forming the first spiral pore channel and the second spiral pore channel in the bonded upper silicon substrate and the bonded lower silicon substrate;

and 4, electroplating the first spiral pore canal and the second spiral pore canal to form a first solenoid and a second solenoid, and obtaining the MEMS square-shaped solenoid transformer.

6. The method according to claim 5, wherein the electroplating of the upper core in the core slot of the upper silicon substrate comprises:

registering a metal mask plate with an iron core groove pattern with an iron core groove on the lower surface of the upper silicon substrate, and then clinging the metal mask plate to the lower surface of the upper silicon substrate;

performing magnetron sputtering on the lower surface of the upper silicon substrate to form metal nickel or metal cobalt with a second preset thickness as a seed layer, and electroplating iron-nickel alloy or iron-cobalt alloy with a third preset thickness in an iron core groove of the upper silicon substrate to obtain an upper iron core; accordingly, the number of the first and second electrodes,

the electroplating in the iron core groove of the lower silicon substrate to form the lower iron core specifically comprises the following steps:

registering a metal mask plate with an iron core groove pattern with an iron core groove on the upper surface of the lower silicon substrate, and then clinging the metal mask plate to the upper surface of the lower silicon substrate;

and after carrying out magnetron sputtering on the upper surface of the lower silicon substrate to obtain metal nickel or metal cobalt with a second preset thickness as a seed layer, electroplating iron-nickel alloy or iron-cobalt alloy with a third preset thickness in an iron core groove of the lower silicon substrate to obtain a lower iron core.

7. The method of claim 5, wherein said fabricating the upper silicon substrate further comprises:

according to the structures and the positions of the four pins, deeply etching four pin grooves on the upper surface of the first silicon wafer after the first oxidation; accordingly, the number of the first and second electrodes,

the step 4 further comprises the following steps:

and electroplating to form the four pins in the four pin grooves.

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