WO2020029360A1 - Capteur - Google Patents

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Publication number
WO2020029360A1
WO2020029360A1 PCT/CN2018/104432 CN2018104432W WO2020029360A1 WO 2020029360 A1 WO2020029360 A1 WO 2020029360A1 CN 2018104432 W CN2018104432 W CN 2018104432W WO 2020029360 A1 WO2020029360 A1 WO 2020029360A1
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WIPO (PCT)
Prior art keywords
magnet
diaphragm
cantilever
magnetoresistive sensor
substrate
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PCT/CN2018/104432
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English (en)
Chinese (zh)
Inventor
邹泉波
冷群文
王喆
Original Assignee
歌尔股份有限公司
北京航空航天大学青岛研究院
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Publication of WO2020029360A1 publication Critical patent/WO2020029360A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage

Definitions

  • the present invention relates to the field of measurement. More specifically, the present invention relates to a sensor, such as a microphone, a pressure sensor, and a displacement sensor.
  • a sensor such as a microphone, a pressure sensor, and a displacement sensor.
  • the plate capacitor includes a substrate and a back plate and a diaphragm formed on the substrate. There is a gap between the back plate and the diaphragm, so that the back plate and the diaphragm constitute a flat plate type. Capacitor sensing structure.
  • the microphone In order to take full advantage of the mechanical sensitivity of the diaphragm, the microphone needs to design a huge back cavity with environmental pressure to ensure that the rigidity of the flowing air is far from the diaphragm.
  • the volume of the dorsal cavity is usually much larger than 1 mm 3 , for example, it is usually designed to be 1-15 mm 3 .
  • the microphone chip when packaged, its cavity needs to be opened. This limits the design of the smallest MEMS microphone package (> 3mm 3 ).
  • a detection structure of a single magnet or a single magnetoresistive sensor is used. Because the linear range of the magnetoresistive sensor is very narrow, the detection sensitivity of the magnetoresistive sensor is very low.
  • Fig. 7a shows a coordinate diagram of the distribution of a single magnet and a single magnetoresistive sensor in the prior art, where the center position of the magnet is the coordinate origin.
  • Fig. 7b shows a simulation diagram of the magnetic field distribution in Fig. 7a.
  • the size of the permanent magnet is 10 ⁇ m * 5 ⁇ m * 0.5 ⁇ m.
  • the abscissa represents the vertical distance z (m) of the magnetoresistive sensor relative to the center of the permanent magnet, and the ordinate represents the magnetic field strength Bx (T) and the magnetic field change gradient dB / dz (T / m).
  • Line a in the figure represents the change curve of Bx (T) with z (m)
  • line b represents the change curve of magnetic field change gradient dB / dz (T / m) with z (m).
  • the starting point of the linear detection area of the magnetoresistive sensor is a position about 18 ⁇ m from the center z (m) of the permanent magnet.
  • the magnetic field change gradient dB / dz (T / m) is about 4700 T / m (below 10 4 T / m).
  • V B is the GMR bias
  • S R ( ⁇ R / R) / ⁇ B
  • a sensor including a first substrate and a diaphragm supported above the first substrate by a first spacer, and further comprising a detection structure for outputting an electric signal characterizing a deformation of the diaphragm.
  • the detection structure includes a first magnet, a second magnet, and a magnetoresistive sensor disposed in a common magnetic field formed by the first magnet and the second magnet; in an initial position, the magnetoresistive sensor is located in a magnetic field direction of the first magnet and The magnetic field direction of the second magnet is opposite; the magnetoresistive sensor is configured to sense a change in the common magnetic field of the first magnet and the second magnet during the vibration of the diaphragm and output a changed electrical signal;
  • the first magnet and the second magnet are sequentially arranged horizontally on the diaphragm in the same direction of the magnetic poles, and the magnetoresistive sensor is disposed on a first substrate at a position corresponding to the first magnet and the second magnet;
  • the first magnet and the second magnet are sequentially horizontally arranged on the first substrate in the same manner as the directions of the magnetic poles, and the magnetoresistive sensor is disposed on the diaphragm corresponding to the first magnet and the second magnet.
  • the first substrate has a hollow cavity communicating with the outside, and further includes a cantilever spaced from the diaphragm, the cantilever and the diaphragm are suspended above the cavity in the first substrate, and the diaphragm An open cavity is enclosed with the first spacer and the substrate; the driving device is arranged on the diaphragm and / or on a cantilever;
  • the first magnet and the second magnet are sequentially arranged horizontally on the diaphragm in the same direction of the magnetic poles, and the magnetoresistive sensor is disposed on a cantilever corresponding to the first magnet and the second magnet;
  • the first magnet and the second magnet are sequentially horizontally arranged on the cantilever in the same direction as the magnetic pole direction, and the magnetoresistive sensor is disposed on the diaphragm corresponding to the first magnet and the second magnet.
  • the first substrate, the first spacer, and the diaphragm surround a vacuum cavity; wherein the static deflection distance of the diaphragm under atmospheric pressure is smaller than the distance between the diaphragm and the first substrate;
  • the first magnet and the second magnet are symmetrical with respect to the magnetoresistive sensor.
  • the first substrate has a hollow cavity in communication with the outside, and a first cantilever and a second cantilever are respectively provided on opposite sides of the diaphragm, and the diaphragm and the first cantilever and the second cantilever are connected to each other.
  • the driving device is arranged on the diaphragm and / or the first cantilever and / or the second cantilever;
  • the magnetoresistive sensor is disposed on the diaphragm, the first magnet and the second magnet are disposed on the first cantilever and the second cantilever, respectively, and the first magnet and the second magnet are arranged in opposite directions of the magnetic poles.
  • the first magnet and the second magnet are magnetized films.
  • the relative position between the magnetoresistive sensor, the first magnet, and the second magnet can be fine-tuned by the driving device to ensure that the magnetoresistive sensor can work in a suitable magnetic field, which avoids the influence on the sensitivity of the sensor due to manufacturing and assembly errors.
  • 1 to 4 are schematic structural diagrams of four different embodiments of the sensor of the present invention.
  • 5a is a coordinate diagram of a magnetoresistive sensor and two magnets in the embodiments shown in FIG. 1 and FIG. 2.
  • FIG. 5b is a simulation diagram of the magnetic field distribution in the embodiments shown in FIG. 1 and FIG. 2.
  • FIG. 6a is a coordinate diagram of a magnetoresistive sensor and two magnets in the embodiments shown in FIG. 3 and FIG. 4.
  • FIG. 6a is a coordinate diagram of a magnetoresistive sensor and two magnets in the embodiments shown in FIG. 3 and FIG. 4.
  • FIG. 6b is a simulation diagram of the magnetic field distribution in the embodiments shown in FIG. 3 and FIG. 4.
  • FIG. 6b is a simulation diagram of the magnetic field distribution in the embodiments shown in FIG. 3 and FIG. 4.
  • Fig. 7a is a coordinate diagram of a single magnetoresistive sensor and a single magnet in the prior art.
  • Fig. 7b is a simulation diagram of a magnetic field distribution in the prior art shown in Fig. 7a.
  • the sensor provided by the present invention may be a microphone, a pressure sensor, a displacement sensor, or other sensors well known to those skilled in the art.
  • a pressure sensor when applied to a pressure sensor, the diaphragm is sensitive to external pressure, and changes in external pressure will drive the diaphragm to deform.
  • a displacement sensor When applied to a displacement sensor, a driving rod can be set to be connected with the diaphragm, and the diaphragm is deformed by the driving rod, which will not be listed one by one here.
  • a microphone is taken as an example to describe the technical solution of the present invention in detail.
  • a microphone provided by the present invention includes a substrate, a diaphragm supported above the substrate through a spacer, and a detection structure for outputting an electrical signal characterizing a deformation of the diaphragm.
  • the detection structure When sound acts on the diaphragm, the diaphragm will deform under the effect of sound pressure.
  • the detection structure will output a changed electrical signal to characterize the degree of deformation of the diaphragm and achieve acoustic-electrical conversion.
  • the detection structure includes a first magnet, a second magnet, and a magnetoresistive sensor disposed in a common magnetic field formed by the first magnet and the second magnet.
  • the first magnet and the second magnet are arranged correspondingly so that the magnetic fields of the two magnets interact with each other.
  • the magnetoresistive sensor simultaneously senses the magnetic fields of the first magnet and the second magnet, so that the magnetoresistive sensor can sense the change in the common magnetic field of the first magnet and the second magnet during the vibration of the diaphragm, thereby outputting a changed electrical signal.
  • the magnetic fields of the two magnets are opposite to each other.
  • the common magnetic field of the two magnets received by the magnetoresistive sensor is weakened compared to a single magnet.
  • the initial position of the magnetoresistive sensor is a position where the magnetic field of the first magnet is opposite to that of the second magnet.
  • the ideal position between the magnetoresistive sensor and the first and second magnets is fixed.
  • a drive device is required to adjust the magnetoresistive sensor.
  • the driving device may be, for example, a piezoelectric sheet or an electrode sheet for providing an electrostatic force.
  • a piezoelectric sheet for example, AlN, PZT, or ZnO materials, which are well known to those skilled in the art, may be used.
  • the piezoelectric sheet shifts the components carried by a certain distance, and the position is adjusted.
  • the present invention provides a microphone including a first substrate 100 and a diaphragm 120 supported above the first substrate 100 through a first spacer 140.
  • the first substrate 100, the first spacer 140, and the diaphragm 102 surround a vacuum cavity 130.
  • the first substrate 100 of the present invention may be made of single crystal silicon or other materials well known to those skilled in the art, and the first spacer 140 and the first spacer 140 may be formed by layer-by-layer deposition, patterning, and sacrificial processes.
  • the vibration film 120 and the vacuum chamber 130 supported on the first substrate 100 can be sealed by, for example, low pressure plasma enhanced chemical vapor deposition (PECVD) at 200-350 ° C.
  • PECVD low pressure plasma enhanced chemical vapor deposition
  • This MEMS process belongs to the common knowledge of those skilled in the art and will not be described in detail here.
  • the vacuum chamber 130 is preferably less than 1 kPa, which makes the residual gas viscosity in the vacuum chamber 130 much lower than the air viscosity at standard pressure.
  • the diaphragm 120 Since a vacuum cavity lower than atmospheric pressure is formed between the diaphragm 120 and the first substrate 100, the diaphragm 120 will statically deflect under atmospheric pressure and no sound pressure, that is, the diaphragm 120 will face the first substrate 100. The direction is statically deflected.
  • the static deflection distance of the diaphragm 120 is designed to be smaller than the distance between the diaphragm 120 and the first substrate 100. This can be achieved mainly by changing the rigidity of the diaphragm 120 and / or changing the distance between the diaphragm 120 and the first substrate 100.
  • the size of the diaphragm 120 can be increased.
  • the rigidity of the diaphragm 120 can also be improved by selecting a suitable material of the diaphragm 120.
  • the diaphragm 120 may be designed to have a mechanical sensitivity of 0.02 to 0.9 nm / Pa. That is to say, each time the pressure of 1Pa, the diaphragm 120 will deflect from 0.02-0.9nm.
  • the rigidity of this diaphragm 120 is 10-100 times that of the traditional diaphragm, making the diaphragm 120 hard enough to resist the external Atmospheric pressure.
  • the MEMS microphone can use a highly sensitive detection member.
  • the high-sensitivity detection member may use a magnetoresistive sensor 110 that outputs an electrical signal according to a change in a magnetic field, such as a giant magnetoresistive sensor (GMR) or a tunnel magnetoresistive sensor (TMR).
  • GMR giant magnetoresistive sensor
  • TMR tunnel magnetoresistive sensor
  • a first magnet 150 and a second magnet 160 are provided on the first substrate 100 at a position on the side of the vacuum chamber 130.
  • the first magnet 150 and the second magnet 160 may be magnetic films, and the magnetic films may be directly used.
  • the magnetic material may be formed by magnetizing the thin film.
  • the magnetic thin film may be made of CoCrPt or CoPt.
  • the first magnet 150 and the second magnet 160 are disposed adjacent to each other, and are sequentially horizontally arranged on the first substrate 100 in the same manner in the direction of the magnetic poles. For example, at the time of fabrication, two independent films are formed first, and then the two films are magnetized simultaneously. After magnetization, referring to the view direction of FIG. 3, the left side of the first magnet 150 and the second magnet 160 are both N poles, and the right side are S poles; vice versa.
  • the magnetoresistive sensor 110 is disposed on one side of the vacuum chamber on the diaphragm 120, and the magnetoresistive sensor 110 is disposed corresponding to the first magnet 150 and the second magnet 160 on the first substrate 100.
  • a lead portion may be provided on one side of the vacuum chamber on the diaphragm 120, and one end of the lead portion is connected to the magnetoresistive sensor 110, and the other end extends from the diaphragm 120 to the first
  • a pad 190 is formed outside the diaphragm 120 at the position of the spacer 140.
  • the diaphragm 120 When the diaphragm 120 receives external sound pressure, the diaphragm 120 deforms in the direction of the first substrate 100. At this time, the magnetoresistive sensor 110 on the diaphragm 120 is close to the first magnet 150 and the second magnet 160, so that the magnetic The resistance sensor 110 can sense a change in a common magnetic field of the first magnet 150 and the second magnet 160, thereby outputting a changed electrical signal, and achieving acoustic-electric conversion.
  • the magnetoresistive sensor 110 may be disposed above the center line of the first magnet 150 and the second magnet 160.
  • the magnetic field directions of the first magnet 150 and the second magnet 160 are both returned from the N pole to the S pole. Therefore, at a position above the center line of the first magnet 150 and the second magnet 160, the magnetic directions of the first magnet 150 and the second magnet 160 are opposite and the magnetic field strength is approximately the same. This position is the initial position of the magnetoresistive sensor 110.
  • the magnetoresistive sensor 110 vibrates with the diaphragm 120
  • the magnetoresistive sensor 110 vibrates up and down at the initial position. Because the magnetoresistive sensor 110 is affected by two magnets at the same time, the two magnets cooperate to reduce the strength of the entire magnetic field, and increase the sensitivity of the magnetic field change within the linear range of the magnetoresistive sensor 110, and finally increase the magnetoresistance The detection sensitivity of the sensor 110.
  • 6c represent the vertical distance z (m) of the magnetoresistive sensor with respect to the center position of the two magnets, and the ordinate represents the magnetic field strength B (T) and the magnetic field change gradient dB / dx (T / m) .
  • Line a1 in the figure represents the change curve of B (T) with z (m)
  • line b1 represents the change curve of magnetic field change gradient dB / dx (T / m) with z (m).
  • the magnetic field strength of the initial position of the magnetoresistive sensor 110 is 0, that is, the position where B (T) in line a1 is 0, and at this time, z (m) is about 4 ⁇ m.
  • the distance between the center of each magnet is 4 ⁇ m.
  • the value of the line b1 is approximately 2.0 * 10 5 T / m. That is, the gradient of the magnetic field change at this position is 2.0 * 10 5 T / m.
  • the area of the line b1 on the left and right sides of the initial position is relatively flat, which ensures that the magnetoresistive sensor 110 can be located in its linear detection area.
  • the magnetoresistive sensor 110 is disposed on a side of the diaphragm 120 away from the vacuum chamber 130, that is, the magnetoresistive sensor 110 is disposed on the outside or the upper side of the diaphragm 120.
  • the magnetoresistive sensor 110 is between the first magnet 150 and the second magnet 160. Although it is blocked by the diaphragm 120, the magnetic fields of the first magnet 150 and the second magnet 160 can still pass through the diaphragm 120 and be sensed by the magnetoresistive sensor 110, so it will not affect the performance of the MEMS microphone.
  • the magnetoresistive sensor 110 may also be disposed in the multilayer film 120 to protect the magnetoresistive sensor 110.
  • the diaphragm 120 may adopt a composite structure. For example, in order to form a vacuum cavity, a cover layer having a sacrificial hole needs to be provided first, and the sacrificial layer below the cover layer is etched through the sacrificial hole; A filling layer is then deposited over the cover layer to seal the sacrificial holes in the cover layer to form a vacuum cavity.
  • the magnetoresistive sensor 11 may be disposed on or in a filling layer, and finally a passivation layer is deposited for protection, so that the magnetoresistive sensor 110 is formed in the composite structure of the diaphragm 120.
  • the first magnet 150 and the second magnet 160 may be disposed on the diaphragm 120 and the magnetoresistive sensor 110 may be disposed on the first substrate 100.
  • the diaphragm 120 vibrates, the positions of the first magnet 150 and the second magnet 160 are changed, and the same effect can be achieved, which is not described in detail here.
  • a driving device such as a piezoelectric sheet 200 can be disposed on the diaphragm 120, and the piezoelectric sheet 200 can be passed by a person skilled in the art.
  • the well-known manner is formed at the corresponding position of the diaphragm 120, and the electrical signal of the piezoelectric sheet 200 can be drawn out through the conductive portion, and a corresponding external pad is formed at an outer position of the diaphragm 120.
  • a DC bias voltage can be applied to the piezoelectric sheet 200, and the piezoelectric sheet 120 can be used to drive the diaphragm 120 to generate a certain displacement, and finally make the magnetic
  • the resistance sensor 110 is located on the centerline position of the first magnet 150 and the second magnet 160, thereby ensuring the sensitivity of the sensor.
  • the first substrate 100 has a hollow cavity 101 communicating with the outside, and further includes a cantilever 171 spaced from the diaphragm 120, an edge of the diaphragm 120 and The end of the cantilever 171 is directly or indirectly connected to the first substrate 100, so that the diaphragm 120 and the main body portion of the cantilever 171 are suspended above the cavity 101 in the first substrate 100.
  • the cantilever 171 and the diaphragm 120 are separated by a first spacer.
  • the height of the first spacer is the initial gap between the diaphragm 120 and the cantilever 171. Because the structure of the back plate is abandoned, the structural design of the cantilever 171 is adopted, so that the diaphragm 120, the first spacer, and the cantilever 171 form an open cavity, and the cantilever 171 will not seal the cavity. This is completely different from the traditional sealed cavity enclosed between the diaphragm and the back plate.
  • the first magnet 150, the second magnet 160, and the magnetoresistive sensor 110 can be selectively disposed on the diaphragm 120 and the cantilever 171.
  • the microphone of the present invention may be an arrangement manner of the diaphragm above, cantilever down, or an arrangement manner of the diaphragm below, and the diaphragm above.
  • the cantilever 171 is located below the diaphragm 120. Referring to FIG. 4, one end of the cantilever 171 may be connected to the first substrate 100, and the other end may extend toward the axis direction of the hollow cavity and be suspended above the hollow cavity. The edge of the diaphragm 120 is supported above the cantilever 171 through the first spacer 140.
  • one cantilever 171 may be provided, one end of which is directly or indirectly connected to the first substrate 100, and the other end extends toward the center of the diaphragm 120 and is suspended.
  • Two cantilever arms 171 can also be provided, and they can be arranged according to specific needs.
  • the cantilever 171 spans the hollow cavity, and both ends thereof are directly or indirectly connected to the first substrate 100.
  • a support portion for supporting the cantilever 171 is formed in the hollow cavity of the first substrate 100, and the shape and size of the support portion are matched with the cantilever 171, so that the support portion will not face the
  • the hollow cavity of the first substrate 100 causes excessive blocking.
  • the support portion and the first substrate 100 may be integrated.
  • the structure of the support portion is formed at the same time.
  • the first magnet 150 and the second magnet 160 may be disposed on the cantilever 171, and the magnetoresistive sensor 110 may be disposed on the diaphragm 120.
  • the position of the driving magnetoresistive sensor 110 changes.
  • the first magnet 150 and the second magnet 160 may be provided on the diaphragm 120, and the magnetoresistive sensor 110 may be provided on the cantilever 171.
  • the diaphragm 120 vibrates, the positions of the first magnet 150 and the second magnet 160 are changed, which is not described in detail here.
  • a driving device such as the piezoelectric sheet 200 may be disposed on the diaphragm 120, and the piezoelectric sheet 200 may be well-known by those skilled in the art.
  • the method is formed at the corresponding position of the diaphragm 120, and the electrical signal of the piezoelectric sheet 200 can be drawn out through the conductive portion, and a corresponding external pad is formed at an outer position of the diaphragm 120.
  • a DC bias voltage can be applied to the piezoelectric sheet 200, and the piezoelectric sheet 120 can be used to drive the diaphragm 120 to generate a certain displacement, and finally make the magnetic
  • the resistance sensor 110 is located on the centerline position of the first magnet 150 and the second magnet 160, thereby ensuring the sensitivity of the sensor.
  • the piezoelectric sheet 200 can also be set on the cantilever 171, and the relative position between the magnetoresistive sensor 110 and the first magnet 150 and the second magnet 160 can be calibrated by changing the position of the cantilever 171. Not specific herein
  • a piezoelectric sheet is provided on the diaphragm 120 and the cantilever 171 at the same time, and the relative positions between the magnetoresistive sensor 110 and the first magnet 150 and the second magnet 160 are calibrated by the two piezoelectric sheets. Specific description.
  • the present invention provides a microphone including a first substrate 1 and a diaphragm 2 supported above the first substrate 1 through a first spacer 6.
  • the first substrate 1 and the first spacer 6 The diaphragm 2 surrounds a vacuum chamber 5.
  • the first substrate 1 of the present invention may be made of single crystal silicon or other materials well known to those skilled in the art, and the first spacer 6 and the first spacer 6 may be formed by layer-by-layer deposition, patterning, and sacrificial processes.
  • the diaphragm 2 supported on the first substrate 1 and the vacuum chamber 5 can be sealed, for example, by a low pressure plasma enhanced chemical vapor deposition (PECVD) at 200-350 ° C.
  • PECVD low pressure plasma enhanced chemical vapor deposition
  • This MEMS process belongs to the common knowledge of those skilled in the art and will not be described in detail here.
  • the vacuum chamber 5 is preferably less than 1 kPa, which makes the residual gas viscosity in the vacuum chamber 5 much lower than the air viscosity at standard pressure.
  • a first cantilever 3 is also provided above the diaphragm 2, and the first cantilever 3 and the diaphragm 2 are separated by a second spacer (no reference numeral is added in FIG. 1).
  • the height of the second spacer is the diaphragm.
  • the diaphragm 2, the second spacer portion, and the first cantilever 3 form an open type cavity, so that the first cantilever 3 does not seal the cavity.
  • first cantilever 3 may be connected to the second spacer, and the other end may extend toward the axis direction of the receiving cavity and be suspended above the receiving cavity.
  • one of the first cantilever arms 3 may be provided, one end of which is directly or indirectly connected to the second spacer, and the other end extends toward the center of the diaphragm 2 and is suspended.
  • the first cantilever 3 can also be provided with two, and can be arranged according to specific needs.
  • the first cantilever 3 spans the cavity, and both ends thereof are directly or indirectly connected to the second spacer.
  • the microphone may employ a highly sensitive detection member.
  • the high-sensitivity detection member may use a magnetoresistive sensor 8 that outputs an electrical signal according to a change in a magnetic field, such as a giant magnetoresistive sensor (GMR) or a tunnel magnetoresistive sensor (TMR).
  • GMR giant magnetoresistive sensor
  • TMR tunnel magnetoresistive sensor
  • the first magnet 7 can be formed on the first substrate 1 by deposition or other means known to those skilled in the art. Specifically, at the time of fabrication, an insulating layer 10 can be deposited on the first substrate 1 first, and then a first magnet 7 can be formed by a deposition and patterning process. In order to protect the first magnet 7, it can also be deposited on the insulating layer 10 A layer of passivation layer 11 covering the first magnet 7.
  • the insulating layer and the passivation layer can be made of materials well known to those skilled in the art, and will not be described in detail here.
  • the second magnet 9 can also be formed on the first cantilever 3 in the same manner, which will not be described in detail here.
  • the first magnet 7 and the second magnet 9 are arranged on the first substrate 1 and the first cantilever 3 in a manner that the magnetic pole directions are opposite to each other. Referring to the view direction of FIG. 1, when the left side of the first magnet 7 is N-pole and the right side is S-pole, the left side of the second magnet 9 is S-pole and the right side is N-pole; vice versa.
  • the magnetoresistive sensor 8 is disposed on the diaphragm 2.
  • a lead portion may be provided on the diaphragm 2, and one end of the lead portion is connected to the magnetoresistive sensor 8. The other end extends to the position of the first spacer 6 on the diaphragm 2, and a pad 15 is formed on the outside of the diaphragm 2. It should be noted that the lead portion may pass through to the outside of the first substrate 1 and form a pad, which is not described in detail here.
  • the diaphragm 2 When the diaphragm 2 is subjected to external sound pressure, the diaphragm 2 is deformed in the direction of the first substrate 1. At this time, the magnetoresistive sensor 8 on the diaphragm 2 is close to the first magnet 7 and away from the second magnet 9, so that The magnetoresistive sensor 8 can sense the change of the common magnetic field of the first magnet 7 and the second magnet 9 and output a changed electric signal, thereby realizing the conversion of acoustic electricity.
  • the first magnet 7 and the second magnet 9 are preferably symmetrical with respect to the magnetoresistive sensor 8, and this position of the magnetoresistive sensor 8 is the initial position.
  • the magnetoresistive sensor 8 may be disposed on a side of the diaphragm 2 away from the vacuum chamber 5, or on the side of the diaphragm 2 near the vacuum chamber 5, or the magnetoresistive sensor 8 may be disposed in the diaphragm 2.
  • the diaphragm 2 may adopt a composite structure. For example, in order to form a vacuum cavity, a cover layer 12 having a sacrificial hole needs to be provided first, and the sacrificial layer below the cover layer 12 is etched through the sacrificial hole. Afterwards, a filling layer 13 is deposited on the cover layer 12 to close the sacrificial holes on the cover layer 12 to form a vacuum cavity.
  • the magnetoresistive sensor 8 may be disposed on or in the filling layer 13, and finally a passivation layer 14 is deposited for protection.
  • the magnetoresistive sensor 8 is formed in the composite structure of the diaphragm 120 and is located at the center of the first magnet 7 and the second magnet 9.
  • the magnetoresistive sensor 8 When the magnetoresistive sensor 8 vibrates with the diaphragm 2, the magnetoresistive sensor 8 will use the center position as an initial position to perform up and down vibration. At this initial position, the magnetoresistive sensor 8 is subjected to the same magnitude of the magnetic field of the two magnets, and their directions are opposite. For example, when the diaphragm 2 is deformed toward the cantilever 3, the magnetoresistive sensor 8 is closer to the first magnet 7 and away from the second magnet 9. According to the characteristics of the magnet, it can be known that the magnetoresistive sensor 8 is more affected by the first magnet 7 than it is. Affected by the second magnet 8; vice versa.
  • Fig. 5a shows a coordinate diagram of the distribution of two magnets and a magnetoresistive sensor in the embodiment shown in Fig. 1.
  • the origin position is located at the center position of the lower magnet.
  • Fig. 5b shows a simulation diagram of a magnetic field distribution in the embodiment shown in Fig. 1.
  • the size of both magnets is 2 ⁇ m * 1 ⁇ m * 0.1 ⁇ m, and the distance between the two magnets is 2 ⁇ m.
  • the abscissa in FIG. 5b represents the vertical distance z (m) of the magnetoresistive sensor with respect to the center position of the lower magnet, and the ordinate represents the magnetic field strength Bx (T) and the magnetic field change gradient dB / dz (T / m).
  • Line a2 in the figure represents the change curve of Bx (T) with z (m)
  • line b2 represents the change curve of the magnetic field change gradient dB / dz (T / m) with z (m).
  • the magnetic field strength of the initial position of the magnetoresistive sensor 8 is 0, that is, the position where Bx (T) in line a2 is 0, and at this time, z (m) is about 1 ⁇ m (1.0E-06), that is, the initial position of the magnetoresistive sensor 8 is
  • the magnetoresistive sensor 8 is located at a distance of 1 ⁇ m from the center of the lower magnet.
  • the value of the line b2 is approximately 1.6 * 10 6 T / m. That is, the gradient of magnetic field change at this position is 1.6 * 10 6 T / m.
  • the sensitivity to magnetic field changes is greatly improved.
  • the area of the line b2 on the left and right sides of the initial position is relatively flat, which ensures that the magnetoresistive sensor 8 can be located in its linear detection area.
  • a vacuum cavity is enclosed between the diaphragm 2 and the first substrate 1.
  • the viscosity of the air in the vacuum cavity is much lower than the air viscosity in the ambient pressure, so that the acoustic resistance can reduce the vibration of the diaphragm 2 Effect, improving the signal-to-noise ratio of the microphone.
  • the MEMS microphone of this structure does not require a large-capacity back cavity, the overall size of the MEMS microphone can be greatly reduced, and the reliability of the microphone is enhanced.
  • the piezoelectric sheet 16 may be disposed on the first cantilever 3, and the piezoelectric sheet 16 may be formed at a corresponding position of the first cantilever 3 in a manner known to those skilled in the art, and the piezoelectric sheet may be formed by a conductive part An electrical signal of 16 is drawn, and a corresponding external pad is formed on the outer position of the first cantilever 3.
  • a DC bias voltage can be applied to the piezoelectric sheet 16 to drive the first cantilever 3 to a certain displacement through the piezoelectric sheet, thereby By changing the position of the second magnet 9, the magnetoresistive sensor 8 is finally located at the center of the first magnet 7 and the second magnet 9, thereby ensuring the sensitivity of the sensor.
  • the first substrate 1 has a hollow cavity 16 communicating with the outside, and further includes a second cantilever located below the diaphragm 2 and separated from the diaphragm 2. 17.
  • the edge of the diaphragm 2 and the end of the second cantilever 17 are directly or indirectly connected to the first substrate 1, so that the main part of the diaphragm 2 and the second cantilever 17 is suspended in the cavity 16 of the first substrate 1.
  • the second cantilever 17 and the diaphragm 2 are separated by a first spacer.
  • the height of the first spacer is the initial gap between the diaphragm 2 and the second cantilever 17. Because the structure of the back plate is abandoned, the structural design of the second cantilever 17 is adopted, so that the diaphragm 2 and the first spacer and the second cantilever 17 form an open cavity, and the second cantilever 17 will not face each other. This cavity creates a seal, which is completely different from the traditionally sealed cavity enclosed between the conventional diaphragm and the back plate.
  • One end of the second cantilever 17 may be connected to the first substrate 1, and the other end may extend toward the axis direction of the hollow cavity and be suspended above the hollow cavity.
  • the edge of the diaphragm 2 is supported above the second cantilever 17 through the first spacer.
  • one of the second cantilever arms 17 may be provided, one end of which is directly or indirectly connected to the first substrate 1, and the other end extends toward the center of the diaphragm 2 and is suspended.
  • the second cantilever 17 can also be provided with two, and can be arranged according to specific needs.
  • the second cantilever 17 spans the hollow cavity, and both ends thereof are directly or indirectly connected to the first substrate 1.
  • a support portion for supporting the second cantilever 17 is formed in the hollow cavity of the first substrate 1, and the shape and size of the support portion match the second cantilever 17. Therefore, the support portion does not cause excessive blocking to the hollow cavity of the first substrate 1.
  • the support portion and the first substrate 1 may be integrated.
  • the structure of the support portion is formed at the same time.
  • the first magnet 7 may be disposed on the second cantilever arm 17 to cooperate with the second magnet 9 on the first cantilever arm 3, which is not described in detail here.
  • the piezoelectric sheet 16 may be disposed on the second cantilever 17.
  • the piezoelectric sheet 16 may be formed at a corresponding position of the second cantilever 17 in a manner well known to those skilled in the art, and the piezoelectric sheet may be formed by a conductive portion. 16 electrical signals.
  • a DC bias voltage can be applied to the piezoelectric sheet 16 to drive the second cantilever 17 to a certain displacement through the piezoelectric sheet, thereby By changing the position of the first magnet 7, the magnetoresistive sensor 8 is finally located at the center position of the first magnet 7 and the second magnet 9, thereby ensuring the sensitivity of the sensor.
  • the piezoelectric sheet 16 can also be set on the diaphragm 2 or the first cantilever 3, and the magnetoresistive sensors 8 and 8 can be calibrated by changing the position of the diaphragm 2 or changing the position of the first cantilever 3. The relative positions between the first magnet 7 and the second magnet 9.
  • a piezoelectric sheet 16 may be selectively provided on the first cantilever 3, the diaphragm 2, and the second cantilever 17, and the two or three piezoelectric sheets may be used to calibrate the magnetoresistive sensor 8 and the first magnet 7. The relative position between the two magnets 9 is not described in detail here.

Abstract

La présente invention concerne un capteur, comprenant une structure de détection dotée d'un premier aimant, d'un second aimant et d'un capteur magnétorésistif placé dans un champ magnétique commun formé par le premier aimant et le second aimant. En position initiale, le capteur magnétorésistif est situé dans une position dans laquelle la direction de champ magnétique du premier aimant est opposée à la direction de champ magnétique du second aimant. Le capteur magnétorésistif est conçu pour, pendant la vibration d'une membrane, détecter une variation dans le champ magnétique commun du premier aimant et du second aimant, puis délivrer en sortie un signal électrique de variation. L'invention concerne en outre un dispositif d'entraînement conçu pour ajuster des positions mutuelles entre le capteur magnétorésistif et le premier aimant et le second aimant. Dans le capteur selon la présente invention, la position relative entre le capteur magnétorésistif et le premier aimant et le second aimant peut être ajustée finement au moyen du dispositif d'entraînement, ce qui permet d'utiliser le capteur magnétorésistif dans un champ magnétique approprié, et évite l'impact de la fabrication et des erreurs d'assemblage sur la sensibilité du capteur.
PCT/CN2018/104432 2018-08-06 2018-09-06 Capteur WO2020029360A1 (fr)

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CN110207586B (zh) * 2019-05-23 2020-09-18 潍坊歌尔微电子有限公司 一种磁传感器芯片中磁阻的布置结构及磁传感器芯片
CN110345938B (zh) * 2019-06-25 2021-08-31 潍坊歌尔微电子有限公司 一种晶圆级的磁传感器及电子设备
CN111158528B (zh) * 2019-12-31 2021-06-29 北京航空航天大学 提高压电触摸屏在阶梯力下测力准确度的装置及方法
CN112179478B (zh) * 2020-10-09 2022-09-30 重庆理工大学 一种基于磁电阻效应的悬臂式振动传感器
CN113029204B (zh) * 2021-03-01 2023-06-23 歌尔微电子股份有限公司 传感器和电子设备
CN113613152B (zh) * 2021-07-30 2023-06-30 歌尔微电子股份有限公司 微机电系统麦克风、麦克风单体及电子设备
CN114924419A (zh) * 2022-06-15 2022-08-19 业成科技（成都）有限公司 角度调整装置、抬头显示器及交通工具
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