CN107255737A - A kind of tunnel magnetoresistive formula accelerometer device and method changed based on magnetic direction - Google Patents

Abstract

The invention discloses a tunnel magnetoresistive accelerometer device and a measurement method based on changing the direction of a magnetic field. The device is not only small in size and easy to process, but also has significantly improved measurement sensitivity and precision. The device includes a top structure, a bottom structure, a middle structure and four anchor points. The four anchor points are set on the four corners of the bottom structure and connected between the top structure and the bottom structure. The middle structure is supported by four anchor points. Between the bottom structure and the top structure. The invention can generate a magnetic field perpendicular to the tunnel magneto-resistance sensor and the thickness of the excitation structure is larger to realize a stronger local magnetic field, thereby realizing a tunnel magneto-resistance effect with higher sensitivity; The mass block and the anchor point, under the action of leverage, the sensitivity and measurement accuracy have been significantly improved; at the same time, the accelerometer has a simple structure, small size, and is easy to process; it has the advantages of controllable magnetic field strength and adjustable sensitivity.

Description

Device and method for tunnel magneto-resistive accelerometer based on changing direction of magnetic field

technical field

The invention belongs to the technical field of acceleration measurement, relates to a micro-electromechanical system (MEMS) and a micro-inertial device, and more specifically relates to a tunnel reluctance accelerometer device and a measurement method based on changing the direction of a magnetic field.

Background technique

Quantum tunneling is a quantum property in which microscopic particles such as electrons are able to pass through "walls" that they would not otherwise be able to pass through. The tunnel magnetoresistance effect means that in the "tunnel junction" composed of a ferromagnetic thin film and an intermediate insulating layer, the possibility of electron tunneling through the insulating layer is correlated with the relative magnetization direction of the ferromagnetic layer, and its macroscopic performance is the size of the resistance , the resistance has extremely high resistance sensitivity to changes in the direction of the magnetic field. Tunnel magnetoresistive acceleration mainly uses the input acceleration signal to cause the magnetic field polarization of the two layers of ferromagnetic film in the "tunnel junction" to change, so that the input acceleration can be measured by the change of tunnel magnetoresistance. Since the tunnel magnetoresistance effect is very sensitive to the magnetization direction of the magnetic field, that is, the possibility of electron tunneling through the insulating layer is very sensitive to the change of the magnetization direction of the magnetic field, so that high-precision acceleration detection can be realized, making it a new generation of high-precision silicon micro accelerometer key research areas.

At present, the tunnel magneto-resistive accelerometer devices in the prior art usually have problems such as bulky, low measurement accuracy and low sensitivity, which cannot meet the application requirements.

Contents of the invention

In order to solve the above problems, the present invention discloses a tunnel reluctance accelerometer device based on changing the direction of the magnetic field and a measurement method thereof. The device is not only small in size and easy to process, but also has significantly improved measurement sensitivity and precision.

In order to achieve the above object, the present invention provides the following technical solutions:

A tunnel magneto-resistive accelerometer device based on changing the direction of the magnetic field, including a top structure, a bottom structure, a middle structure and four anchor points, the four anchor points are arranged on the four corners of the bottom structure and connected to the top structure and the bottom structure Between, the middle layer structure is supported between the bottom layer structure and the top layer structure by four anchor points;

The intermediate layer structure includes a mass block, a first sensitive feedback electrode, a second sensitive feedback electrode, a first spacing control electrode, and a second spacing control electrode located on the back of the mass block, a third sensitive feedback electrode located on the back of the mass block, and a second sensitive feedback electrode located on the back of the mass block. Four sensitive feedback electrodes, the third spacing control electrode, the fourth spacing control electrode, the tunnel magnetoresistance excitation structure embedded in the mass block and the two terminal electrodes connected to the front and back of the tunnel magnetoresistance excitation structure are used to isolate the mass block The third insulating layer connected to the tunnel reluctance excitation structure and its two terminal electrodes, the first flexible rod support beam, the second flexible rod support beam, the third flexible rod support beam, and the fourth flexible rod support beam respectively connected to the four corners of the mass block A flexible rod support beam, the first flexible rod support beam is also connected to the second anchor point, the second flexible rod support beam is also connected to the third anchor point, and the third flexible rod support beam is also connected Connected to the fourth anchor point, the fourth flexible rod support beam is also connected to the first anchor point;

The underlying structure includes a first substrate, a first insulating layer arranged on the front of the first substrate 1, a first tunnel magnetoresistive sensor arranged on the front of the first insulating layer, a second tunnel magnetoresistance sensor, and a fifth sensitive feedback sensor. electrode, the sixth sensitive feedback electrode, the fifth interval control electrode, and the sixth interval control electrode;

The top layer structure includes a second substrate, a second insulating layer arranged on the back of the second substrate, a third tunnel magnetoresistive sensor arranged on the back of the second insulating layer, a fourth tunnel magnetoresistance sensor, and a seventh sensitive feedback electrode , the eighth sensitive feedback electrode, the seventh spacing control electrode, and the eighth spacing control electrode.

Further, each flexible rod support beam is L-shaped, one end of which is connected to the mass block, and the other end is connected to the anchor point.

Further, the tunnel magnetoresistance excitation structure includes several cylindrical structures distributed in the proof mass.

Further, the first sensitive feedback electrode, the second sensitive feedback electrode, the first spacing control electrode, and the second spacing control electrode are respectively located on the right, left, front, and rear of the tunnel reluctance excitation structure; the third sensitive feedback The electrode, the fourth sensitive feedback electrode, the third spacing control electrode, and the fourth spacing control electrode are respectively located on the right, left, front, and rear of the tunnel reluctance excitation structure.

Further, in the underlying structure, the first tunnel magnetoresistive sensor and the second tunnel magnetoresistive sensor are located on both sides of the middle part of the first insulating layer and distributed symmetrically along the AB center line, and the two tunnel magnetoresistive sensors are located at the center of the tunnel magnetoresistance excitation structure. Directly below, the fifth sensitive feedback electrode is located between the first tunnel magnetoresistive sensor and the first and second anchor points, and the sixth sensitive feedback electrode is located between the second tunnel magnetoresistive sensor and the third and fourth anchor points Between; the fifth spacing control electrode is located between the two tunnel magnetoresistive sensors and the second anchor point, the third anchor point, the sixth spacing control electrode is located between the two tunnel magnetoresistive sensors and the first anchor point, the fourth anchor point ; The fifth sensitive feedback electrode and the sixth sensitive feedback electrode are located directly below the first sensitive feedback electrode and the second sensitive feedback electrode, and the fifth spacing control electrode and the sixth spacing control electrode are located at the first spacing control electrode and the second spacing control electrode. directly below the electrode.

Further, the fifth sensitive feedback electrode and the sixth sensitive feedback electrode are located on the transverse centerline and on both sides of the two tunnel magnetoresistive sensors; the fifth spacing control electrode and the sixth spacing control electrode are located on the longitudinal centerline, and On both sides of the two tunnel magnetoresistive sensors; the fifth and sixth spacing control electrodes and the first and second spacing control electrodes form a differential torque device to realize the spacing control between the middle layer and the bottom layer; the fifth and sixth sensitive feedback electrodes and the first The first and second sensitive feedback electrodes form two sets of differential control pins, forming a closed loop between the local magnetic field and the detection signal of the tunnel magnetoresistive sensor.

Further, the first tunnel magneto-resistive sensor and the second tunnel magneto-resistive sensor have the same structure, and are connected in series by rectangular blocks in a “serpentine” structure, and the first tunnel magneto-resistive sensor is sequentially arranged with Top layer, free layer, tunnel barrier layer, ferromagnetic layer, antiferromagnetic layer and bottom layer; the magnetic field direction of the ferromagnetic layer is preset by the antiferromagnetic layer, and the magnetic field direction of the free layer is determined by the magnetic field generated by the external tunnel reluctance excitation structure , the magnetic field generated by the tunnel magnetoresistance excitation structure is determined by the applied current.

Further, the two ends of the first tunnel magnetoresistive sensor, the two ends of the second tunnel magnetoresistive sensor, the fifth sensitive feedback electrode, the sixth sensitive feedback electrode, the fifth spacing control electrode, the sixth spacing control electrode, four Each anchor point is drawn out through each electrode lead.

Further, the third tunnel magnetoresistance sensor and the fourth tunnel magnetoresistance sensor in the top layer structure are located in the middle of the second insulating layer and directly above the tunnel magnetoresistance excitation structure; the seventh sensitive feedback electrode is located at the third tunnel magnetoresistance Between the sensor and the first anchor point and the second anchor point, the eighth sensitive feedback electrode is located between the fourth tunnel magnetoresistive sensor and the third anchor point, and between the fourth anchor point; the seventh spacing control electrode is located at the third tunnel magnetoresistance Between the sensor, the fourth tunnel magnetoresistive sensor and the second anchor point, the third anchor point, the eighth spacing control electrode is located at the third tunnel magnetoresistive sensor, the fourth tunnel magnetoresistive sensor and the first anchor point, the fourth anchor point and the seventh sensitive feedback electrode and the eighth sensitive feedback electrode are located directly above the third sensitive feedback electrode and the fourth sensitive feedback electrode, the seventh spacing control electrode and the eighth spacing control electrode are located at the third spacing control electrode, the second spacing control electrode Four spaced directly above the control electrodes.

The measurement method of the tunnel magnetoresistive accelerometer device based on the change of the direction of the magnetic field includes the following steps: applying a voltage to the electrodes at both ends of the tunnel magnetoresistance excitation structure so as to form a current in the tunnel magnetoresistance excitation structure to generate a local magnetic field; when the acceleration signal goes along When the input is from the top layer to the bottom layer, the mass block will be displaced downward, resulting in a smaller distance between the tunnel magnetoresistive excitation structure and the first tunnel magnetoresistive sensor, the second tunnel magnetoresistive sensor and the distance between the third tunnel magnetoresistive sensor, the fourth tunnel magnetoresistive sensor The distance between the tunnel magnetoresistive sensors becomes larger, which causes the magnetic field around the first, second, third, and fourth tunnel magnetoresistive sensors to change; through the measurement of the resistance of the first, second, third, and fourth tunnel magnetoresistive sensors, the external input is realized. measurement of acceleration.

Compared with the prior art, the present invention has the following beneficial effects:

1. Compared with the tunnel accelerometer based on the change of the gap, the magnetic field direction is parallel to the tunnel magnetoresistive sensor and the excitation structure is realized by a magnetic film. The tunnel accelerometer based on the change of the magnetic field direction produces a magnetic field perpendicular to the tunnel magnetoresistive sensor and the thickness of the excitation structure Larger can achieve a stronger local magnetic field, thereby achieving a higher sensitivity tunnel magnetoresistance effect; at the same time, due to the use of four flexible flexible rod support beams to connect the mass block and the anchor point, under the action of leverage, the sensitivity and measurement accuracy are improved. Significantly improved; at the same time, the accelerometer is simple in structure and small in size.

2. The present invention uses a tunnel structure to generate a local magnetic field, which has the advantages of controllable magnetic field strength and adjustable sensitivity, while avoiding the disadvantages of permanent magnet magnetic field attenuation and uncontrollable magnetic field strength.

3. The present invention realizes the tunneling magnetoresistance effect by changing the direction of the magnetic field, without realizing the nm-level gap control of the insulating layer gap between two ferromagnetic layers, and is easier to process and realize the function of the device.

Description of drawings

Fig. 1 (a) is the overall structure schematic diagram of the tunnel reluctance type accelerometer device based on the change of the magnetic field direction provided by the present invention, wherein the left half of the AB center line is viewed from the third anchor point direction to the fourth anchor point direction (that is, Fig. 3 downward), and the right half of the AB center line is a schematic diagram viewed from the direction of the first anchor point to the direction of the second anchor point (that is, upward in Figure 3).

Fig. 1 (b) is another overall structure schematic diagram of the tunnel reluctance accelerometer device based on the change of the magnetic field direction provided by the present invention, wherein the left half of the CD center line is viewed from the third anchor point direction to the second anchor point direction ( That is to the right in FIG. 3 ), and the right half of the CD centerline is a schematic diagram viewed from the direction of the first anchor point to the direction of the fourth anchor point (that is, to the left in FIG. 3 ).

Fig. 2 is a bottom view of the top layer and the middle layer structure.

Figure 3 is a top view of the underlying structure.

Fig. 4 is a schematic diagram of the structure of the tunnel magnetoresistive sensor.

Figure 5 is a wiring diagram of the underlying structure.

Figure 6 is a bottom view of the top structure.

detailed description

The technical solutions provided by the present invention will be described in detail below in conjunction with specific examples. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

As shown in Figure 1, a kind of tunnel reluctance type accelerometer device based on magnetic field direction change, comprises top layer structure, bottom layer structure, middle layer structure and first anchor point 3, the second anchor point 4, the third anchor point 5, The fourth anchor point 6, the four anchor points are set on the four corners of the bottom structure and connected between the top structure and the bottom structure, while the middle layer structure is supported between the bottom structure and the top structure through four anchor points, the top structure and The underlying structure is symmetrically distributed up and down relative to the middle layer, and each component and its distribution are consistent.

As shown in Figure 1 and Figure 2, the intermediate layer structure includes a quality block 17, a first sensitive feedback electrode 18, a second sensitive feedback electrode 20, a third sensitive feedback electrode 34, a fourth sensitive feedback electrode 36, and a first spacing control electrode. 19. The second pitch control electrode 21, the third pitch control electrode 35, the fourth pitch control electrode 37, the tunnel magnetoresistance excitation structure 23, and the two terminal electrodes of the tunnel magnetoresistance excitation structure specifically include the back electrode 24, the front electrode 33, the first The flexible rod support beam 13 , the second flexible rod support beam 14 , the third flexible rod support beam 15 , and the fourth flexible rod support beam 16 . The underlying structure includes a first tunnel magnetoresistance sensor 11, a second tunnel magnetoresistance sensor 12, a fifth sensitive feedback electrode 7, a sixth sensitive feedback electrode 9, a fifth spacing control electrode 8, a sixth spacing control electrode 10, a first insulating Layer 2 and first substrate 1. The top layer structure is the same as the bottom layer structure, including the third tunnel magnetoresistive sensor 27, the fourth tunnel magnetoresistive sensor 28, the seventh sensitive feedback electrode 29, the eighth sensitive feedback electrode 31, the seventh spacing control electrode 30, and the eighth spacing control electrode 32. The second insulating layer 26 and the second substrate 25.

Specifically, the middle layer structure supports the mass in four flexible rod support beams 13, 14, 15, and 16 through the first flexible rod support beam. Between the anchor points; as shown in Figure 2, the four jiaos of the mass block 17 are respectively connected with an L-shaped flexible rod support beam, and the flexible rod support beam includes short rods and long rods connected vertically to each other, and one corner of the mass block 17 is connected to the The short rod is connected, and the long rod is connected to the anchor point corresponding to the other corner on the same side as the connection angle of the short rod on the mass block. The L-shaped flexible rod support beam forms a long leverage, which can amplify the displacement, facilitate the improvement of measurement accuracy and reduce the difficulty of operation. The tunnel magnetoresistance excitation structure 23 is embedded in the proof mass 17 and is separated from the proof mass 17 by the third insulating layer 22. As shown in FIG. distributed in the mass block 17, a symmetrically distributed magnetic field can be formed on both sides of the central position, and the two ends of the tunnel reluctance excitation structure 23 are connected to the two end electrodes of the tunnel reluctance excitation structure; the two end electrodes of the tunnel reluctance excitation structure realize the distributed In connection with the tunnel magneto-resistance excitation structure 23 in the mass block, the third insulating layer 22 is used to isolate the mass block 17 from the tunnel magneto-resistance excitation structure 23 and its two-terminal electrodes. A voltage is applied to the electrodes at both ends of the tunnel magnetoresistance excitation structure, and a local magnetic field 63 is generated in the tunnel magnetoresistance excitation structure 23 due to the existence of current, which provides magnetic field conditions for the tunnel magnetoresistance accelerometer. The first sensitive feedback electrode 18, the second sensitive feedback electrode 20, the first spacing control electrode 19, and the second spacing control electrode 21 are located on the back of the mass block 17, as can be seen from the direction of view in Figure 2, and they are respectively located in the tunnel reluctance excitation structure 23 The right, left, front and rear positions are beneficial to the lead wires of the electrodes; the third sensitive feedback electrode 34, the fourth sensitive feedback electrode 36, the third spacing control electrode 35, and the fourth spacing control electrode 37 are located on the front of the mass block. 2 They are respectively located on the right, left, front and rear of the tunnel reluctance excitation structure 23 in the direction of view, which is beneficial to the leads of the electrodes.

In the underlying structure, the first insulating layer 2 and the lower ends of four anchor points are arranged on the front of the first substrate 1, the first anchor point 3, the second anchor point 4, the third anchor point 5, and the fourth anchor point 6 The lower ends of the lower ends are respectively located at the top left, lower left, upper right, and lower right vertices of the first insulating layer 2 on the front of the first substrate 1; the fifth sensitive feedback electrode 7 and the sixth sensitive feedback electrode are arranged on the front of the first insulating layer 2 9. The fifth pitch control electrode 8 , the sixth pitch control electrode 10 , the first tunnel magnetoresistance sensor 11 , and the second tunnel magnetoresistance sensor 12 . The first tunnel magnetoresistive sensor 11 and the second tunnel magnetoresistive sensor 12 are located on both sides of the middle part of the first insulating layer 2, distributed symmetrically along the center line AB in Figure 3, as shown in Figure 1, the two tunnel magnetoresistive sensors are located Directly below the anti-excitation structure 23, the change of the induced magnetic field can be maximized to realize the optimization of the sensitivity. It should be noted that the distance between the two tunnel magnetoresistive sensors in Fig. 1(a) and Fig. 3 does not correspond to each other, and does not limit the protection scope of this patent, because the first tunnel magnetoresistive sensor 11 and the second tunnel magnetoresistive sensor The distance between the two tunnel magnetoresistive sensors 12 can be adjusted as required. As shown in Figure 3, the fifth sensitive feedback electrode 7 is located between the first tunnel magnetoresistive sensor 11 and the first anchor point 3 and the second anchor point 4, and the sixth sensitive feedback electrode 9 is located between the second tunnel magnetoresistive sensor 12 and the second anchor point 4. Between the third anchor point 5 and the fourth anchor point 6; the fifth spacing control electrode 8 is located between the two tunnel magnetoresistive sensors and the second anchor point 4 and the third anchor point 5; the sixth spacing control electrode 10 is located in the two tunnels Between the magnetoresistive sensor and the first anchor point 3 and the fourth anchor point 6; and it can be seen from FIG. Directly below the sensitive feedback electrode 20 , the fifth spacing control electrode 8 and the sixth spacing controlling electrode 10 are located directly below the first spacing controlling electrode 19 and the second spacing controlling electrode 21 .

Figure 3 is a top view of the bottom layer, in which the first tunnel magnetoresistive sensor 11 and the second tunnel magnetoresistive sensor 12 are connected in series by rectangular blocks in a "serpentine" structure, located at the first anchor point 3, the second anchor point 4 and the second anchor point On the line CD connecting the middle points of the third anchor point 5 and the fourth anchor point 6, and they are located on the line AB connecting the midpoints of the first anchor point 3, the fourth anchor point 6 and the second anchor point 4 and the third anchor point 5 sides. As shown in FIG. 4 , the first tunnel magnetoresistive sensor 11 is sequentially arranged with a top layer 55, a free layer 56, a tunnel barrier layer 57, a ferromagnetic layer 58, an antiferromagnetic layer 59 and a bottom layer 60 from top to bottom; The direction of the magnetic field 58 is preset by the antiferromagnetic layer 59 , the direction of the magnetic field in the free layer 52 is determined by the magnetic field generated by the external tunnel magnetoresistance excitation structure 23 , and the magnetic field generated by the tunnel magnetoresistance excitation structure 23 is determined by the applied current.

The rectangular fifth sensitive feedback electrode 7 and the sixth sensitive feedback electrode 9 are located on the CD line, and on both sides of the two tunnel magnetoresistive sensors; the rectangular fifth spacing control electrode 8 and the sixth spacing control electrode 10 are located on the AB line, and on the Both sides of the two tunnel magnetoresistive sensors; the fifth and sixth spacing control electrodes and the first and second spacing control electrodes form a differential torque device to realize the spacing control between the middle layer and the bottom layer; the fifth and sixth sensitive feedback electrodes and the first 1. The two sensitive feedback electrodes form two sets of differential control pins, forming a closed loop between the local magnetic field and the detection signal of the tunnel magnetoresistive sensor.

As shown in Figure 5, from the electrode lead diagram of the underlying structure, the first end 47 and the second end 48 of the first tunnel magnetoresistive sensor 11 are drawn through the first electrode lead 51 and the second electrode lead 52; The third terminal 49 and the fourth terminal 50 of 12 are drawn out through the third electrode lead wire 53 and the fourth electrode lead wire 54; the fifth sensitive feedback electrode 7 and the sixth sensitive feedback electrode 9 are drawn through the fifth electrode lead wire 46 and the sixth electrode lead wire 44 The fifth pitch control electrode 8 and the sixth pitch control electrode 10 are drawn out through the seventh electrode lead 43 and the eighth electrode lead 45; the four anchor points are respectively passed through the ninth electrode lead 41, the tenth electrode lead 42, the eleventh electrode lead The electrode leads 39 and the twelfth electrode leads 40 are drawn out.

As shown in FIG. 6 , the top layer structure arranges the upper end of the second insulating layer 26 and four anchor points on the back of the second substrate 25, and the first anchor point 3, the second anchor point 4, the third anchor point 5, the fourth anchor point The upper ends of the anchor points 6 are located at the top left, bottom left, top right, and bottom right vertices of the second insulating layer 26 on the back of the second substrate 25 . The back surface of the second insulating layer 26 is arranged with the seventh sensitive feedback electrode 29, the eighth sensitive feedback electrode 31, the seventh pitch control electrode 30, the eighth pitch control electrode 32, the third tunnel magnetoresistive sensor 27, the fourth tunnel magnetoresistance sensor 28. The third tunnel magnetoresistive sensor 27 and the fourth tunnel magnetoresistive sensor 28 are located in the middle of the second insulating layer 26 and directly above the tunnel magnetoresistive excitation structure 23; the seventh sensitive feedback electrode 29 is located between the third tunnel magnetoresistive sensor 27 and Between the first anchor point 3 and the second anchor point 4, the eighth sensitive feedback electrode 31 is located between the fourth tunnel magnetoresistive sensor 28, the third anchor point 5, and the fourth anchor point 6; the seventh spacing control electrode 30 is located at Between the third tunnel magnetoresistance sensor 27, the fourth tunnel magnetoresistance sensor 28 and the second anchor point 4, the third anchor point 5, the eighth distance control electrode 32 is located at the third tunnel magnetoresistance sensor 27, the fourth tunnel magnetoresistance sensor Between the sensor 28 and the first anchor point 3 and the fourth anchor point 6; and the seventh sensitive feedback electrode 29 and the eighth sensitive feedback electrode 31 are located directly above the third sensitive feedback electrode 34 and the fourth sensitive feedback electrode 36. The seven pitch control electrodes 30 and the eighth pitch control electrodes 32 are located directly above the third pitch control electrodes 35 and the fourth pitch control electrodes 37 .

The measurement method of the tunnel magnetoresistive accelerometer device based on the change of the magnetic field direction is as follows:

A voltage is applied to the two terminal electrodes of the tunnel magnetoresistance excitation structure to form a current in the tunnel magnetoresistance excitation structure 23 to generate a local magnetic field 63. When the acceleration signal is input along the direction 38, the mass block 17 is displaced downward, resulting in tunnel magnetoresistance excitation. The distance between the structure 23 and the first tunnel magnetoresistance sensor 11 and the second tunnel magnetoresistance sensor 12 becomes smaller and the distance between the structure 23 and the third tunnel magnetoresistance sensor 27 and the fourth tunnel magnetoresistance sensor 28 becomes larger, thereby causing the first and second tunnel magnetoresistance sensors to The magnetic field around the 3rd and 4th tunnel magnetoresistive sensors changes, and the measurement of the external input acceleration is realized by measuring the resistance of the 1st, 2nd, 3rd and 4th tunnel magnetoresistive sensors.

The technical means disclosed in the solutions of the present invention are not limited to the technical means disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be pointed out that for those skilled in the art, some improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims (10)

1. A tunnel reluctance type accelerometer device based on magnetic field direction change, it is characterized in that: comprise top layer structure, bottom layer structure, middle layer structure and four anchor points, four anchor points are arranged on the four corners of bottom structure, and connect Between the top structure and the bottom structure, the middle structure is supported between the bottom structure and the top structure by four anchor points; The intermediate layer structure includes a quality block (17), a first sensitive feedback electrode (18), a second sensitive feedback electrode (20), a first spacing control electrode (19), a second spacing The control electrode (21), the third sensitive feedback electrode (34), the fourth sensitive feedback electrode (36), the third spacing control electrode (35), and the fourth spacing control electrode (37) located on the back of the mass block are embedded in the mass The tunnel magnetoresistance excitation structure (23) in the block (17) and the two terminal electrodes connected to the front and back sides of the tunnel magnetoresistance excitation structure (23) respectively are used to isolate the mass block (17) from the tunnel magnetoresistance excitation structure (23 ) and the third insulating layer (22) of its two-terminal electrodes, the first flexible rod support beam (13), the second flexible rod support beam (14), and the third flexible rod support beam (13) connected to the four corners of the mass block (17) respectively A flexible rod support beam (15), a fourth flexible rod support beam (16), the first flexible rod support beam (13) is also connected with the second anchor point (4), and the second flexible rod supports The beam (14) is also connected with the third anchor point (5), and the third flexible rod support beam (15) is also connected with the fourth anchor point (6), and the fourth flexible rod support beam (16) Also connected to the first anchor point (3); The underlying structure includes a first substrate (1), a first insulating layer (2) arranged on the front of the first substrate 1, a first tunnel magnetoresistive sensor (11) arranged on the front of the first insulating layer (2) , the second tunnel magnetoresistive sensor (12), the fifth sensitive feedback electrode (7), the sixth sensitive feedback electrode (9), the fifth spacing control electrode (8), and the sixth spacing control electrode (10); The top layer structure includes a second substrate (25), a second insulating layer (26) arranged on the back of the second substrate, a third tunnel magnetoresistive sensor (27) arranged on the back of the second insulating layer, a fourth tunnel A magnetoresistive sensor (28), a seventh sensitive feedback electrode (29), an eighth sensitive feedback electrode (31), a seventh spacing control electrode (30), and an eighth spacing control electrode (32). 2. The tunnel magneto-resistive accelerometer device based on the change of the magnetic field direction according to claim 1, characterized in that: each flexible rod support beam is L-shaped, one end is connected with the mass block, and the other end is connected with the anchor point . 3. The tunnel reluctance accelerometer device based on changing the direction of the magnetic field according to claim 2, characterized in that: the tunnel reluctance excitation structure (23) includes several cylindrical structures distributed in the mass. 4. The tunnel magneto-resistive accelerometer device based on the change of the magnetic field direction according to claim 3, characterized in that: the first sensitive feedback electrode (18), the second sensitive feedback electrode (20), the first spacing control The electrode (19) and the second spacing control electrode (21) are respectively located on the right, left, front and rear sides of the tunnel reluctance excitation structure (23); the third sensitive feedback electrode (34), the fourth sensitive feedback electrode (36 ), the third spacing control electrode (35), and the fourth spacing control electrode (37) are located on the right, left, front, and rear sides of the tunnel reluctance excitation structure (23), respectively. 5. the tunnel magnetoresistive accelerometer device based on the change of magnetic field direction according to claim 1, is characterized in that: first tunnel magnetoresistive sensor (11), the second tunnel magnetoresistive sensor (12) in the described underlying structure Located on both sides of the middle of the first insulating layer (2) and distributed symmetrically along the center line AB, two tunnel magnetoresistive sensors are located directly below the tunnel magnetoresistance excitation structure (23), and the fifth sensitive feedback electrode (7) is located in the first tunnel Between the magnetoresistive sensor (11) and the first anchor point (3) and the second anchor point (4), the sixth sensitive feedback electrode (9) is located at the second tunnel magnetoresistive sensor (12) and the third anchor point (5 ), the fourth anchor point (6); the fifth spacing control electrode (8) is located between the two tunnel magnetoresistive sensors and the second anchor point (4), the third anchor point (5), the sixth spacing control electrode (10) between the two tunnel magnetoresistive sensors and the first anchor point (3) and the fourth anchor point (6); the fifth sensitive feedback electrode (7) and the sixth sensitive feedback electrode (9) are located at the first sensitive feedback Directly below the electrode (18) and the second sensitive feedback electrode (20), the fifth spacing control electrode (8) and the sixth spacing control electrode (10) are located at the first spacing control electrode (19) and the second spacing control electrode ( 21) directly below. 6. The tunnel magneto-resistive accelerometer device based on the change of the magnetic field direction according to claim 5, characterized in that: the fifth sensitive feedback electrode (7) and the sixth sensitive feedback electrode (9) are located on the transverse centerline , and on both sides of the two tunnel magnetoresistive sensors; the fifth spacing control electrode (8) and the sixth spacing control electrode (10) are located on the longitudinal centerline, and on both sides of the two tunnel magnetoresistive sensors; the fifth and sixth spacing control electrodes The electrode and the first and second spacing control electrodes form a differential torque device to realize the spacing control between the middle layer and the bottom layer; the fifth and sixth sensitive feedback electrodes and the first and second sensitive feedback electrodes form two sets of differential control pins, A closed loop is formed between the local magnetic field and the detection signal of the tunnel magnetoresistive sensor. 7. The tunnel magnetoresistive accelerometer device based on the change of the magnetic field direction according to claim 6, characterized in that: the first tunnel magnetoresistive sensor (11), the second tunnel magnetoresistive sensor (12) are identical in structure, All are connected in series by rectangular blocks in a "serpentine" structure, and the first tunnel magneto-resistive sensor (11) is sequentially arranged with a top layer (55), a free layer (56), and a tunnel barrier layer (57) from top to bottom. , ferromagnetic layer (58), antiferromagnetic layer (59) and bottom layer (60); the magnetic field direction of the ferromagnetic layer (58) is preset by the antiferromagnetic layer (59), and the magnetic field direction of the free layer (52) is determined by the outside The magnetic field generated by the tunnel magnetoresistance excitation structure (23) is determined, and the magnetic field generated by the tunnel magnetoresistance excitation structure (23) is determined by the applied current. 8. The tunnel magnetoresistive accelerometer device based on the change of the magnetic field direction according to claim 7, characterized in that: the two ends of the first tunnel magnetoresistive sensor (11), the second tunnel magnetoresistive sensor (12) Both ends, the fifth sensitive feedback electrode (7), the sixth sensitive feedback electrode (9), the fifth spacing control electrode (8), the sixth spacing control electrode (10), and the four anchor points are drawn out through the lead wires of the electrodes . 9. The tunnel magnetoresistive accelerometer device based on the change of magnetic field direction according to claim 1, characterized in that: the third tunnel magnetoresistive sensor (27) and the fourth tunnel magnetoresistive sensor (28) in the top layer structure Located in the middle of the second insulating layer (26) and directly above the tunnel magnetoresistance excitation structure (23); the seventh sensitive feedback electrode (29) is located between the third tunnel magnetoresistance sensor (27) and the first anchor point (3) , between the second anchor point (4), the eighth sensitive feedback electrode (31) is located between the fourth tunnel magnetoresistive sensor (28) and the third anchor point (5), the fourth anchor point (6); the seventh The spacing control electrode (30) is located between the third tunnel magnetoresistance sensor (27), the fourth tunnel magnetoresistance sensor (28) and the second anchor point (4), the third anchor point (5), and the eighth spacing control electrode (32) between the third tunnel magnetoresistance sensor (27), the fourth tunnel magnetoresistance sensor (28) and the first anchor point (3), the fourth anchor point (6); and the seventh sensitive feedback electrode (29 ), the eighth sensitive feedback electrode (31) is located directly above the third sensitive feedback electrode (34) and the fourth sensitive feedback electrode (36), the seventh spacing control electrode (30), and the eighth spacing control electrode (32) are located Directly above the third spacing control electrode (35) and the fourth spacing control electrode (37). 10. The measuring method based on the tunnel magneto-resistance accelerometer device that the direction of the magnetic field changes, realizes based on the tunnel magneto-resistance type accelerometer device that changes the direction of the magnetic field according to any one of claims 1 to 10, comprising the steps of: The two-terminal electrodes of the tunnel magnetoresistance excitation structure apply voltage to form a current in the tunnel magnetoresistance excitation structure to generate a local magnetic field; when the acceleration signal is input along the direction from the top layer to the bottom layer, the mass block is displaced downward, resulting in the tunnel magnetoresistance excitation structure The distance from the first tunnel magneto-resistive sensor and the second tunnel magneto-resistive sensor becomes smaller and the distance from the third tunnel magneto-resistive sensor and the fourth tunnel magneto-resistive sensor becomes larger, thus causing the first, second, third, and fourth tunnel magneto-resistive sensors The magnetic field around the resistance sensor changes; the measurement of the external input acceleration is realized by measuring the resistance of the first, second, third and fourth tunnel magnetoresistive sensors.