CN203658561U - Single-chip reference bridge type magnetic sensor for high-intensity magnetic field - Google Patents

Abstract

The utility model discloses a single-chip reference bridge type magnetic sensor for a high-intensity magnetic field. The sensor comprises a substrate, a reference arm, an induction arm, shielding structures and attenuators. The reference arm comprises at least two rows/columns of reference element strings and at least two rows/columns of induction element strings, and the induction arm also comprises at least two rows/columns of reference element strings and at least two rows/columns of induction element strings; and the reference element strings and the induction element strings are arranged in a mutually interlaced manner, each reference element string is corresponding provided with one shielding structure, each induction element string is correspondingly provided with one attenuator, magnetic resistance elements are selected from one kind of AMR, GMR or TMR sensing elements, and the shielding structures and the attenuators are long rectangular strip arrays made of a permalloy ferromagnetic material. The sensor can be achieved on three electrical bridge structures, i.e., a quasi bridge, a reference half bridge and a reference full bridge. The sensor has the advantages of low power consumption, good linearity, the wide working range and the like, and can works in the high-intensity magnetic field.

Description

A single-chip reference bridge magnetic sensor for high-intensity magnetic fields

technical field

The utility model relates to the technical field of magnetic sensors, in particular to a single-chip reference bridge magnetic sensor used in high-intensity magnetic fields.

Background technique

Magnetic sensors are widely used in modern industries and electronic products to measure physical parameters such as current, position, and direction by inducing magnetic field strength . In the prior art, there are many different types of sensors used to measure the magnetic field and other parameters, such as Hall elements , Anisotropic Magnetoresistance (AMR) elements or Giant Magnetoresistance (GMR) A magnetic sensor whose element is a sensitive element.

Although the Hall magnetic sensor can work in a high-intensity magnetic field, it has disadvantages such as low sensitivity, high power consumption, and poor linearity. Although the AMR magnetic sensor has higher sensitivity than the Hall sensor, its manufacturing process is complicated, the power consumption is high, and it is not suitable for high-intensity magnetic fields. GMR magnetic sensors have higher sensitivity than Hall magnetic sensors, but their linear range is low and they are not suitable for high-intensity magnetic fields.

TMR (Tunnel MagnetoResistance) magnetic sensor is a new type of magnetoresistance effect sensor that has been applied in industry in recent years. It uses the tunnel magnetoresistance effect of magnetic multilayer film materials to sense magnetic fields. And the GMR magnetic sensor has higher sensitivity, lower power consumption, better linearity and wider working range. However, the existing TMR magnetic sensors are still not suitable for working in high-intensity magnetic fields, and the linear range is not wide enough.

Contents of the invention

The purpose of the utility model is to overcome the above problems in the prior art and provide a single-chip reference bridge magnetic sensor suitable for high-intensity magnetic fields.

In order to achieve the above-mentioned technical purpose and achieve the above-mentioned technical effect, the utility model is realized through the following technical solutions:

The utility model provides a single-chip reference bridge type magnetic sensor for high-intensity magnetic fields, the sensor comprising:

a substrate;

At least one reference arm deposited on the substrate, the reference arm includes at least one row/column of reference element strings composed of one or at least two identical magnetoresistive sensing elements electrically connected;

At least one sensing arm deposited on the substrate, the sensing arm includes at least one row/column of sensing element strings composed of one or at least two identical magnetoresistive sensing elements electrically connected;

At least one attenuator and at least two shielding structures, the attenuators and the shielding structures are arranged alternately and at intervals, the attenuators and the shielding structures have the same shape, and the width and area of the shielding structures are respectively larger than the The width and area of the attenuator are large;

The reference arm is connected to the sensing arm to form a bridge;

Each of the reference element strings is correspondingly provided with a shielding structure, and each of the sensing element strings is correspondingly provided with an attenuator, the reference element strings are located below or above the shielding structure, and the sensing element strings are located at the below or above the attenuator;

The number of rows/columns of the reference element string and the sensing element string are the same, and they are arranged at intervals along the longitudinal or transverse direction;

The gain coefficient of the magnetic field at the induction element string is greater than the gain coefficient of the magnetic field at the reference element string.

Preferably, the magnetoresistive sensing elements constituting the reference element string and the sensing element string are selected from AMR, GMR, and TMR sensing elements.

Preferably, the magnetoresistance sensing element is a GMR spin valve structure, a GMR multi-layer film structure, a TMR spin valve structure or a TMR three-layer film structure.

Preferably, the electric bridge is a half bridge, a full bridge or a quasi bridge.

Preferably, the number of the magnetoresistive sensing elements on the sensing arm and the reference arm is the same.

Preferably, there is a distance L between each sensing element string and adjacent reference element strings, and when the number of attenuators is odd, there are two adjacent reference element strings in the middle And the distance between the two is 2L. When the number of the attenuators is an even number, there are two adjacent inductive element strings in the middle and the distance between the two is 2L.

Preferably, the number N of the attenuators is not less than the number of rows/columns of the inductive element string, the number M of the shielding structure is not less than the number of rows/columns of the reference element string, and N< M, where N and M are both positive integers.

Preferably, the substrate includes an integrated circuit, or is connected to other substrates including an integrated circuit.

Preferably, the integrated circuit is CMOS, BiCMOS, Bipolar, BCDMOS or SOI, and the reference arm and the sensing arm are directly deposited on the integrated circuit of the substrate.

Preferably, the substrate is an ASIC chip, and the ASIC chip contains any one or at least two circuits of an offset circuit, a gain circuit, a calibration circuit, a temperature compensation circuit and a logic circuit.

Preferably, the logic circuit is a digital switch circuit or a rotation angle calculation circuit.

Preferably, the shape of the shielding structure and the attenuator is a strip-shaped array extending horizontally or vertically.

Preferably, the shielding structure and the attenuator are composed of the same material, which is a soft ferromagnetic alloy, and the soft ferromagnetic alloy contains one element or at least two elements among Ni, Fe and Co.

Preferably, the input and output connection ends of the single-chip reference bridge magnetic sensor are electrically connected to the input and output connection ends of the semiconductor package, and the method of the semiconductor package includes pad wire bonding, flip chip, ball grid array packaging, Wafer-level packaging or chip-on-board packaging.

Preferably, the working magnetic field strength of the single-chip reference bridge magnetic sensor is 20-500 Gauss.

Preferably, the shielding structure completely covers the reference element string.

Compared with the prior art, the utility model has the following beneficial effects: low power consumption, good linearity, wide working range and suitable for high-intensity magnetic fields.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiment technology of the present invention, the accompanying drawings that need to be used in the technical description of the embodiment will be briefly introduced below. Obviously, the accompanying drawings in the following description are only the embodiment of the present invention. For some embodiments, those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort.

FIG. 1 is a schematic structural diagram of a single-chip bridge-type magnetic sensor in the prior art.

FIG. 2 is a schematic structural diagram of a single-chip reference bridge magnetic sensor of the present invention.

FIG. 3 is another structural schematic diagram of the single-chip reference bridge magnetic sensor of the present invention.

FIG. 4 is a magnetic field distribution diagram of the single-chip reference bridge magnetic sensor of the present invention in an external magnetic field.

FIG. 5 is a relationship curve between the positions of the reference element string and the inductive element string and the corresponding gain coefficients in the present invention.

FIG. 6 is a relationship curve between the positions of the reference element string and the inductive element string and the corresponding gain coefficients in the prior art.

FIG. 7 is the response curves of magnetoresistive sensing elements with TMR and GMR spin valve structures.

Fig. 8 is the response curves of the magnetoresistive sensing elements with the TMR three-layer film structure and the GMR multi-layer film structure.

Figure 9 is the response curve of the magnetoresistive sensing element with the structure of AMR Barber-pole (similar to the rotating color column at the entrance of the barber shop).

Fig. 10 is a conversion characteristic curve with or without an attenuator for a magnetic sensor with a TMR spin valve structure in the present invention.

Fig. 11 is the conversion characteristic curve of the magnetic sensor with or without the attenuator in the TMR three-layer film structure in the utility model.

                                                                                                    

Detailed ways

The content of the invention of the utility model will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a schematic structural diagram of a single-chip bridge-type magnetic sensor disclosed in patent application 201310203311.3 in the prior art. The sensor includes a substrate 1, an inductive element string 2, a reference element string 3, a shielding structure 4, an electrical connection conductor 6, and four pads 7-10 for input and output connections, which are respectively used as the power supply terminal Vbias and the ground terminal GND , Voltage output terminals V+, V-. The sensing element string 2 and the reference element string 3 are alternately arranged, the sensing element string 2 is located in the gap between the two shielding structures 4 , and the reference element string 3 is located below the shielding structure 4 . The sensing arm, the reference arm and the pads 7-10 are all connected by electrical connection conductors 6 . The sensor has the advantages of high sensitivity, good linearity, and small offset, but it is easy to saturate, and its applicable maximum magnetic field strength is about 100 Gauss, so it cannot be used in a higher-intensity magnetic field.

Example

Fig. 2 is a schematic structural diagram of a single-chip reference bridge magnetic sensor in the present invention. It differs from the sensor shown in FIG. 1 in that: the sensor also includes attenuators 5 arranged at intervals from the shielding structure 4, and the number N of attenuators 5 is not less than the row of inductive element strings 2 /number of columns, the number M of the shielding structure 4 is not less than the number of rows/columns of the reference element string 3, and N<M, N and M are both positive integers, N is 5, and M is 6 in FIG. 2 . The shape of the attenuator 5 is the same as that of the shielding structure 4, preferably a strip-shaped array extending horizontally/vertically, and their constituent materials are also the same, all of which are composed of one or several elements selected from Ni, Fe and Co Soft ferromagnetic alloys can also be non-ferromagnetic materials, but are not limited to the above materials. The sensing element string 2 and the reference element string 3 each consist of at least one row/column electrically connected to one or at least two identical magnetoresistive sensing elements, preferably, the magnetoresistive sensing elements are AMR, GMR or TMR sensing elements , and the number of magnetoresistive sensing elements contained in the sensing element string 2 and the reference element string 3 is the same, and the magnetization direction of the pinned layer is also the same. The inductive element strings 2 and the reference element strings 3 are arranged alternately, each inductive element string 2 and the adjacent reference element string 3 are separated by a distance L, but for an odd number of attenuators 5 as shown in Figure 2, the middle There are two adjacent reference element strings 3 with a distance of 2L between them. For an even number of attenuators 5 as shown in Figure 3, there are two adjacent inductive element strings 2 in the middle with a distance of 2L between them. The spacing L is very small, preferably 20-100 microns. Each sensing element string 2 is correspondingly provided with an attenuator 5, and each reference element string 3 is correspondingly provided with a shielding structure 4, and the sensing element string 2 and the reference element string 3 can be respectively placed above the attenuator 5 and the shielding structure 4 Or below, as shown in Figure 2 is placed below the situation. The width and area of the shielding structure 4 are larger than the width and area of the attenuator 5, which is large enough to completely cover the reference element string 3, so that the magnetic field at the reference element string 3 can be greatly attenuated or even completely shielded, The magnetic field sensed by the sensing element string 2 will be attenuated under the action of the attenuator 5, but the attenuation range is not very large, so that the gain coefficient Asns of the magnetic field at the sensing element string 2 is greater than that at the reference element string 3 The gain factor Aref of the magnetic field. The sensing arm formed by connecting the sensing element strings 2 with each other and the reference arm formed by connecting the reference element strings 3 are electrically connected to form an electric bridge. The input and output terminals of the bridge are respectively the power supply end Vbias 7, the ground end GND 8, and the voltage Output terminal V+ 9, V- 10. The elements on the sensor are connected through electrical connection conductors 6 .

An integrated circuit can also be printed on the substrate 1, or be connected with another substrate printed with an integrated circuit. Preferably, the printed integrated circuit can be CMOS (Complementary Metal Oxide Semiconductor, complementary metal oxide material semiconductor), BiCMOS (bipolar complementary metal oxide semiconductor bipolar complementary metal oxide semiconductor), Bipolar, BCDMOS or SOI (Silicon-On-Insulator, silicon on insulating substrate), the reference arm and sensing arm are directly deposited on the substrate 1 on the integrated circuit. In addition, the substrate 1 can also be an ASIC (Application Specific Integrated Circuit) chip, which contains any one of an offset circuit, a gain circuit (gain circuit), a calibration circuit, a temperature compensation circuit, and a logic circuit (Logic Circuit). One or more application circuits, where the logic circuit can also be a digital switch circuit or a rotation angle calculation circuit, but it is not limited to the above circuits.

In this embodiment, pads are used for input and output connections, but semiconductor packaging methods such as flip-chip, ball grid array packaging, wafer-level packaging, and chip-on-board packaging can also be used. The sensor can be used in the magnetic field of 20~500 Gauss.

FIG. 4 is a magnetic field distribution diagram of the sensing element string 2 and the reference element string 3 in an external magnetic field. In the figure, the direction of the applied magnetic field is 11. The magnetoresistive sensing elements constituting the sensing element string 2 and the reference element string 3 are TMR sensing elements. It can be seen from the figure that the magnetic field at the reference element string 3 is greatly attenuated by the shielding structure, while the attenuation of the magnetic field at the inductive element string 2 is smaller than the former. FIG. 5 is a relationship curve between the positions of the sensing element string 2 and the reference element string 3 corresponding to FIG. 4 and the gain coefficients at the corresponding positions. The positions represented by the horizontal axis in the figure are expressed in the form of proportional distances. It can be seen from Fig. 5 that the gain coefficient Asns of the magnetic field amplitude at the induction element string 2 and the gain coefficient Aref of the magnetic field amplitude at the reference element string 3 are both between 0 and 1, and the gain coefficient Asns is greater than Aref, also That is to say, the attenuation amplitude of the magnetic field at the reference element string 3 is larger than the attenuation amplitude of the magnetic field at the inductive element string 2, which is consistent with the conclusion obtained from FIG. 4 .

Figure 6 is a relationship curve between the position of the sensing element string 2 and the reference element string 3 of the corresponding sensor structure in Figure 1 and the gain coefficient at the corresponding position. For the convenience of comparison, the numbers of reference element strings 3 and inductive element strings 2 are the same as those in FIG. 5 . Comparing the two curves 12 and 13 in Fig. 5 and Fig. 6, it can be found that the magnetic field amplitude at the inductive element string 2 places in the utility model is greatly attenuated, so even if the single chip reference bridge type magnetic sensor in the utility model is placed In a high-intensity magnetic field, the magnetic field sensed by the sensor is an attenuated magnetic field. As long as it is within its saturation range, the sensor can still work normally.

Fig. 7 is the response curves when the magnetoresistive sensing elements are TMR and GMR spin valve structures. When the direction of the applied magnetic field 11 is parallel to the magnetization direction 19 of the pinned layer, and the intensity of the applied magnetic field is greater than -Bs+Bo 25, the magnetization direction 18 of the magnetic free layer is parallel to the direction of the applied magnetic field 11, and then parallel to the direction of the pinned layer. The magnetization directions 19 are parallel, and the magnetic resistance of the TMR element is the smallest at this time, which is _RL 21 . When the direction of the applied magnetic field 11 is antiparallel to the magnetization direction 19 of the pinned layer, and the intensity of the applied magnetic field is greater than Bs+Bo 26, the magnetization direction 18 of the magnetic free layer is parallel to the direction of the applied magnetic field 11, and then parallel to the direction of the pinned layer. The magnetization direction 19 is antiparallel, and the reluctance of the TMR element is the largest at this time, which is R _H 22. When the intensity of the applied magnetic field 11 is Bo 23, the magnetization direction 18 of the magnetic free layer is perpendicular to the magnetization direction 19 of the pinned layer, at this moment, the magnetic resistance of the TMR element is the intermediate value of _RL 21 and R _H 22, namely ( R _L +R _H )/2. The magnetic field between -Bs+Bo 25 and Bs+Bo 26 is the measuring range of the single-chip linear bridge magnetic field sensor. As can be seen from the figure, the curve 20 is linear between -Bs+Bo 25 and Bs+Bo 26,

           Resistance change rate

For TMR spin valves, the resistance change rate can reach up to 200%, and for GMR spin valves, the resistance change rate is only 10%.

Fig. 8 is a response curve when the magnetoresistive sensing element has a TMR three-layer film structure and a GMR multi-layer film structure. When the direction of the applied magnetic field 11 is parallel to the magnetization direction 19 of the pinned layer, and the strength of the applied magnetic field is greater than -Bs 31 or Bs 32, the magnetization direction 18 of the magnetic free layer is parallel to the direction of the applied magnetic field 11, and then is parallel to the direction of the pinned layer. The magnetization direction 19 of the MTJ element is parallel, and the reluctance of the MTJ element is the smallest at this time, which is _RL 28. When the external magnetic field is 0, the magnetization direction 18 of the magnetic free layer is antiparallel to the magnetization direction 19 of the pinned layer, and the reluctance of the MTJ element is the largest at this time, which is R _H 27. - The magnetic field between Bs 31 and Bs 32 is the measuring range of the sensor. It can be seen from the figure that the curves 29 and 30 are linear between -Bs 31 and Bs 32, and the resistance change rate of the magnetoresistive element can reach up to 200%.

Figure 9 is the response curve when the magnetoresistive sensing element is an AMR Barber-pole structure. It can be seen from the figure that the resistance change rate of this kind of magnetoresistive element is about 1%.

Fig. 10 is a conversion characteristic curve of a single-chip reference bridge sensor with a TMR spin valve structure as a magnetoresistive sensing element with or without an attenuator. Curve 15 shows the situation without an attenuator, curve 16 shows the situation with an attenuator, the horizontal axis is the magnitude of the applied magnetic field, and the vertical axis is the ratio between the sensor output voltage and the power supply voltage. Comparing the two curves, it can be seen that the linear range of the magnetic field corresponding to the curve 15 is about 35 Oersted, and the linear range of the magnetic field corresponding to the curve 16 is about 150 Oersted. It can be seen that after using the attenuator, the sensor The linear operating range is significantly wider.

Fig. 11 is a conversion characteristic curve of a single-chip reference bridge sensor with or without an attenuator whose magnetoresistive sensing element is a TMR three-layer film structure. Curve 33 represents the situation without an attenuator, curve 34 represents the situation with an attenuator, the horizontal axis is the magnitude of the applied magnetic field, and the vertical axis is the ratio between the sensor output voltage and the power supply voltage. Comparing these two curves, it can be seen that after using the attenuator, the working range of the sensor is significantly wider.

The above discussion is the case where the bridge is a full bridge. Since the working principle of the half bridge and quasi-bridge is the same as that of the full bridge, it will not be repeated here. The conclusions obtained above are also applicable to the single bridge structure of the half bridge and quasi-bridge. The chip is referenced to a bridge-type magnetic sensor.

The above descriptions are only preferred embodiments of the utility model, and are not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present utility model shall be included in the protection scope of the present utility model.

Claims (15)

1. a single-chip reference bridge type magnetic sensor for high-intensity magnetic field, it is characterized in that, the sensor comprises: a substrate; At least one reference arm deposited on the substrate, the reference arm includes at least one row/column of reference element strings composed of one or at least two identical magnetoresistive sensing elements electrically connected; At least one sensing arm deposited on the substrate, the sensing arm includes at least one row/column of sensing element strings composed of one or at least two identical magnetoresistive sensing elements electrically connected; At least one attenuator and at least two shielding structures, the attenuators and the shielding structures are arranged alternately and at intervals, the attenuators and the shielding structures have the same shape, and the width and area of the shielding structures are respectively larger than the The width and area of the attenuator are large; The reference arm is connected to the sensing arm to form a bridge; Each of the reference element strings is correspondingly provided with a shielding structure, and each of the sensing element strings is correspondingly provided with an attenuator, the reference element strings are located below or above the shielding structure, and the sensing element strings are located at the below or above the attenuator; The number of rows/columns of the reference element string and the sensing element string are the same, and they are arranged in a staggered interval along the vertical or horizontal direction; The gain coefficient of the magnetic field at the induction element string is greater than the gain coefficient of the magnetic field at the reference element string. 2. single-chip reference bridge type magnetic sensor according to claim 1, is characterized in that, constitutes described reference element string and the described magnetoresistive sensor element that constitutes described inductive element string is selected from AMR, GMR, TMR One of the sensing elements. 3. The single-chip reference bridge magnetic sensor according to claim 2, wherein the magnetoresistive sensing element is a GMR spin valve structure, a GMR multilayer film structure, a TMR spin valve structure or a three-layer TMR Membrane structure. 4. The single-chip reference bridge magnetic sensor according to any one of claims 1-3, wherein the bridge is a half-bridge, a full-bridge or a quasi-bridge. 5 . The single-chip reference bridge magnetic sensor according to claim 1 , wherein the numbers of the magnetoresistive sensing elements on the sensing arm and the reference arm are the same. 6. The single-chip reference bridge-type magnetic sensor according to claim 1, characterized in that, each of the inductive element strings and the adjacent reference element strings are separated by a distance L, when the attenuator When the number is an odd number, there are two adjacent reference element strings in the middle and the distance between the two is 2L; when the number of the attenuators is even, there are two inductive element strings in the middle Adjacent and the spacing between the two is 2L. 7. The single-chip reference bridge magnetic sensor according to claim 1, wherein the number N of the attenuators is not less than the number of rows/columns of the inductive element string, and the number of the shielding structures M is not less than the number of rows/columns of the reference element string, and N<M, where N and M are both positive integers. 8. The single-chip reference bridge magnetic sensor according to claim 1, wherein the substrate includes an integrated circuit, or is connected to other substrates including an integrated circuit. 9. The single-chip reference bridge magnetic sensor according to claim 8, wherein the integrated circuit is CMOS, BiCMOS, Bipolar, BCDMOS or SOI, and the reference arm and the sensing arm are directly deposited on the The integrated circuit above the substrate. 10. single-chip reference bridge type magnetic sensor according to claim 8, is characterized in that, described substrate is an ASIC chip, and described ASIC chip contains offset circuit, gain circuit, calibration circuit, temperature compensation circuit and logic ( logic) any one or at least two circuits in the circuit. 11. The single-chip reference bridge magnetic sensor according to claim 10, wherein the logic circuit is a digital switch circuit or a rotation angle calculation circuit. 12 . The single-chip reference bridge magnetic sensor according to claim 1 , wherein the shape of the shielding structure and the attenuator are long strip arrays extending horizontally or vertically. 13 . 13. The single-chip reference bridge-type magnetic sensor according to claim 1, wherein the input-output connection end of the single-chip reference bridge-type magnetic sensor is electrically connected to the input-output connection end of the semiconductor package, and the semiconductor package Common methods include pad wire bonding, flip chip, ball grid array packaging, wafer level packaging, or chip-on-board packaging. 14. The single-chip reference bridge magnetic sensor according to claim 1, wherein the working magnetic field strength of the single-chip reference bridge magnetic sensor is 20-500 Gauss. 15. The single-chip reference bridge magnetic sensor according to claim 1, wherein the shielding structure completely covers the reference element string.

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