WO2024109749A1 - 传感器芯片及其制作方法、电容传感器和电子设备 - Google Patents

传感器芯片及其制作方法、电容传感器和电子设备 Download PDF

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Publication number
WO2024109749A1
WO2024109749A1 PCT/CN2023/133014 CN2023133014W WO2024109749A1 WO 2024109749 A1 WO2024109749 A1 WO 2024109749A1 CN 2023133014 W CN2023133014 W CN 2023133014W WO 2024109749 A1 WO2024109749 A1 WO 2024109749A1
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Prior art keywords
electrode
diaphragm
sensor chip
movable electrode
substrate
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PCT/CN2023/133014
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English (en)
French (fr)
Inventor
邹泉波
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潍坊歌尔微电子有限公司
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Publication of WO2024109749A1 publication Critical patent/WO2024109749A1/zh

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/06—Forming electrodes or interconnections, e.g. leads or terminals
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals

Definitions

  • the present disclosure relates to the field of sensor technology, and more specifically, to a sensor chip and a manufacturing method thereof, a capacitive sensor and an electronic device.
  • a vertical movable component with grounded or near-ground potential is arranged above a plane with high voltage V+, ground GND, and high voltage V+ fixed electrode strips.
  • the electric field is uneven around the movable component, and an electrostatic repulsion force upward on the movable component as a whole can be generated above the critical position point, thereby eliminating the problem of static electricity settling.
  • the electric field component in the Z-axis direction is smaller at the diaphragm, so an order of magnitude higher bias, i.e., high bias, is required to achieve the same sensitivity.
  • the purpose of the present disclosure is to provide a new technical solution for a sensor chip and a manufacturing method thereof, a capacitive sensor and an electronic device.
  • an embodiment of the present disclosure provides a sensor chip.
  • the sensor chip includes a substrate and at least one sensing component disposed on the substrate, the sensing component includes a diaphragm, a fixed electrode component and a movable electrode, the diaphragm is supported on one side of the substrate and is connected to the substrate. Enclosed to form a vacuum chamber;
  • the fixed electrode assembly includes three fixed electrodes, the three fixed electrodes include two high bias electrodes and a ground electrode between the two high bias electrodes, the ground electrode and the two high bias electrodes are both arranged on the substrate and located at one side of the vacuum chamber, the movable electrode is arranged on the diaphragm, the movable electrode is configured to be used as a detection node, the DC potential is virtually grounded, and the movable electrode is opposite to the ground electrode;
  • a support column is provided on one side of the diaphragm located in the vacuum chamber, and the support column is configured to enable the distance between the diaphragm and the high bias electrode to be greater than a critical distance under atmospheric pressure;
  • the electrostatic force exerted on the movable electrode in the electric field is in a direction away from the high bias electrode, and an electrostatic repulsive force is formed between the movable electrode and the high bias electrode.
  • the diaphragm and the movable electrode can move in a direction away from the high bias electrode, and the movable electrode generates an AC signal output voltage when working.
  • the vacuum degree of the vacuum chamber is 100Pa-1000Pa.
  • the high bias voltage applied to the two high bias electrodes is +100V to +300V.
  • the supporting column is provided in plurality, the supporting column is located in the vacuum chamber, and the plurality of supporting columns are spaced apart on one side of the diaphragm.
  • each of the sensing components includes three support columns, one of which corresponds to the position of the ground electrode, and the remaining two support columns are arranged in a one-to-one correspondence with the two high bias electrodes.
  • the multiple sensing components are arranged on one side surface of the substrate to form an array of a set shape; wherein the sensing components are independently arranged and the sensing components are connected in parallel.
  • the multiple sensing components are arranged on one side surface of the substrate to form a set array; wherein the vacuum chambers of each sensing component are interconnected.
  • two adjacent sensing components are configured to share the same high bias electrode.
  • a first dielectric layer is provided on one side of the substrate where the sensing component is provided, and the ground electrode and the two high bias electrodes are both formed on the first dielectric layer;
  • a second dielectric layer is formed on the diaphragm at one side of the vacuum chamber, and the movable electrode is formed on the second dielectric layer.
  • the movable electrode and the supporting column are located on the same side of the diaphragm and inside the vacuum chamber; or, the movable electrode is embedded in the diaphragm and located outside the vacuum chamber.
  • an embodiment of the present disclosure provides a method for manufacturing a sensor chip as described in the first aspect.
  • the manufacturing method comprises:
  • a first dielectric layer is covered on one side of the substrate, and at least one fixed electrode assembly is formed on the first dielectric layer; wherein each of the fixed electrode assemblies includes three fixed electrodes, and the three fixed electrodes include two high bias electrodes and a ground electrode between the two high bias electrodes;
  • a sacrificial layer is covered on one side of the substrate where the fixed electrode assembly is provided, and a blind hole with a set depth is formed on the side of the sacrificial layer away from the substrate, wherein each fixed electrode corresponds to one blind hole;
  • a second dielectric layer is covered on one side of the sacrificial layer where the blind hole is provided, the second dielectric layer is also embedded in the blind hole and blocks the blind hole to form a support column, and a movable electrode is formed on the second dielectric layer so that the position of the movable electrode corresponds to the position of the ground electrode one by one;
  • First through holes penetrating the sacrificial layer and the second dielectric layer are respectively formed on both sides of each of the fixed electrode assemblies;
  • the second dielectric layer is covered with a diaphragm and the first through hole is blocked, the movable electrode is fixedly connected to the diaphragm, and a second through hole is formed on the diaphragm and the second dielectric layer;
  • the sacrificial layer between two adjacent first through holes is removed to form a cavity, at least the fixed electrode assembly and the support column are encapsulated in the cavity, and the second through hole is connected to the cavity;
  • the second through hole is sealed, and the cavity is made to have a set vacuum degree to form a vacuum cavity;
  • a conductive through hole is provided at the edge of the substrate, the conductive through hole penetrates the sacrificial layer, the second dielectric layer and the diaphragm, and one end of the conductive through hole is electrically connected to the high bias electrode;
  • An electrical connection portion is disposed at the other end of the conductive through hole, and the electrical connection portion is disposed on the surface of the diaphragm.
  • the step of fixedly connecting the diaphragm and the movable electrode includes:
  • the movable electrode is connected to a side of the diaphragm located in the vacuum chamber so that the movable electrode is located inside the vacuum chamber; or the movable electrode is embedded in the diaphragm so that the movable electrode is located outside the vacuum chamber.
  • an embodiment of the present disclosure provides a capacitive sensor.
  • the capacitive sensor comprises:
  • a capacitive sensor characterized in that it comprises:
  • the sensor chip is disposed in the packaging structure.
  • the packaging structure includes a circuit board and a packaging layer arranged on one side of the circuit board, the sensor chip is arranged on the circuit board, and the packaging layer is arranged around the outer periphery of the sensor chip.
  • a temporary protection layer is covered on the sensor chip.
  • the packaging structure includes a circuit board and a shell arranged on one side of the circuit board, and the circuit board and the shell are enclosed to form a containing cavity;
  • the sensor chip is located in the accommodating cavity and is fixedly arranged on the circuit board, and an ASIC chip is also arranged on the circuit board;
  • the housing or the circuit board is provided with a sound hole communicating with the outside.
  • an embodiment of the present disclosure provides an electronic device, wherein the electronic device comprises the capacitive sensor as described in the third aspect.
  • the disclosed embodiment provides a solution for a sensor chip, in which a vacuum sealing cavity structure is arranged on a substrate, and electrostatic repulsion is introduced so that a high bias voltage is always in a vacuum sealing environment, which can eliminate the situation where air breaks through the diaphragm; at the same time, the electrostatic repulsion force generated is used to offset all or part of the atmospheric pressure, so that the diaphragm can be designed to be softer, which is beneficial to improving the mechanical sensitivity of the diaphragm, thereby improving the sensitivity of the formed sensor chip.
  • FIG1 is a schematic diagram of a structure of a sensor chip according to an embodiment of the present disclosure.
  • FIG2 is a second schematic diagram of the structure of the sensor chip according to an embodiment of the present disclosure.
  • FIG3 is a third structural schematic diagram of the sensor chip according to an embodiment of the present disclosure.
  • FIG4 is a fourth structural schematic diagram of the sensor chip according to an embodiment of the present disclosure.
  • FIG5 is a schematic diagram of FEM simulation results of the sensing component in an embodiment of the present disclosure.
  • FIG6 is a schematic diagram of a method for manufacturing a sensor chip according to an embodiment of the present disclosure.
  • FIG. 7 is a second schematic flow chart of a method for manufacturing a sensor chip according to an embodiment of the present disclosure.
  • FIG8 is a schematic diagram of a capacitance sensor according to an embodiment of the present disclosure.
  • FIG9 is a second structural schematic diagram of a capacitive sensor according to an embodiment of the present disclosure.
  • FIG. 10 is a third schematic diagram of the structure of the capacitive sensor according to the embodiment of the present disclosure.
  • a sensor chip is provided, which can be applied to micro-electromechanical system devices such as capacitive microphones and capacitive absolute pressure sensors.
  • Micro-electromechanical system (MEMS) technology is an industrial technology that integrates microelectronics technology and micromechanical engineering.
  • the size of a MEMS device is usually less than a few millimeters, and its internal structure is generally at the micron or even nanometer level.
  • the sensor chip provided by the embodiments of the present disclosure can also be applied to, for example, mechanical sensors.
  • Mechanical sensors are sensors that can detect changes caused by mechanical effects.
  • the mechanical effects here include sound pressure, air pressure, acceleration, deformation caused by stress generated by temperature changes, deformation caused by stress generated by humidity changes, etc.
  • the sensor chip provided in the embodiment of the present disclosure comprises a substrate 1 and at least one sensing component 2 arranged on the substrate 1, wherein the sensing component 2 comprises a diaphragm 3, a fixed electrode component and a movable electrode 7, wherein the diaphragm 3 is supported on one side of the substrate 1 and encloses a vacuum chamber 4 with the substrate 1;
  • the fixed electrode assembly includes three fixed electrodes, the three fixed electrodes include two high bias electrodes 6 and a ground electrode 5 between the two high bias electrodes 6, the ground electrode 5 and the two high bias electrodes 6 are both arranged on the substrate 1 and located on one side of the vacuum chamber 4, the movable electrode 7 is arranged on the diaphragm 3, the movable electrode 7 is configured to be used as a detection node, the DC potential is virtually grounded, and the movable electrode 7 is opposite to the ground electrode 5;
  • a support column 8 is provided on one side of the diaphragm 3 located at the vacuum chamber 4. is configured to enable the distance between the diaphragm 3 and the high bias electrode 6 to be greater than a critical distance under atmospheric pressure;
  • the electrostatic force exerted on the movable electrode 7 in the electric field is in the direction away from the high bias electrode 6, and an electrostatic repulsive force is formed between the movable electrode 7 and the high bias electrode 6.
  • the diaphragm 3 and the movable electrode 7 can move in the direction away from the high bias electrode 6 under the electrostatic repulsive force, and the movable electrode 7 generates an AC signal output voltage when working.
  • the sensor chip provided by the embodiment of the present disclosure is a sensing component with a vacuum cavity 4.
  • the diaphragm 3 in the sensing component 2 can resist atmospheric pressure and prevent static electricity from settling while also having good softness, which greatly improves the sensitivity and signal-to-noise ratio of the entire sensor chip.
  • the existing APS sensor (Absolute Pressure Sensing sensor, i.e., a sensor with a vacuum sealed cavity) can improve sensitivity, but considering the change in atmospheric pressure in the air, the problem of electrostatic sedimentation is difficult to completely avoid directly in the design of the sensor.
  • the existing technology also proposes to use permanent magnet film magnetic suspension to resist atmospheric pressure and prevent electrostatic sedimentation.
  • the diaphragm can be designed to be softer, but this solution requires the introduction of special magnetic materials, which is a great challenge to mass production, cost, and yield.
  • the sensor chip provided by the embodiment of the present disclosure includes a vacuum chamber 4 in the design of the sensing component 2, and introduces electrostatic repulsion, so that the applied high bias voltage is always in a vacuum sealed environment (because the high bias electrode 6 is located in the vacuum chamber 4), thereby eliminating the situation where air breaks through the diaphragm; at the same time, the electrostatic repulsion force is used to offset all or part of the atmospheric pressure, so that the diaphragm 3 can be designed to be softer (that is, with lower hardness), which is beneficial to improving the mechanical sensitivity of the diaphragm 3, thereby greatly improving the sensitivity and signal-to-noise ratio of the formed sensor chip.
  • the sensor chip provided by the embodiment of the present disclosure introduces an electrostatic repulsion mechanism in the APS capacitor structure, so that the high bias voltage is in a vacuum (or dry high dielectric strength gas) sealed environment, which can eliminate the problem of air breaking through the diaphragm; at the same time, the electrostatic repulsion force offsets all or part of the atmospheric pressure, and the diaphragm 3 can be designed to be relatively soft.
  • the softness of the diaphragm 3 is related to its mechanical sensitivity.
  • the mechanical sensitivity of the diaphragm 3 is relatively high, so that the sensitivity Soc ⁇ Sm*Vb/Gap of the formed sensor chip or the capacitive sensor including the sensor chip can be relatively high, but it does not increase the difficulty of process manufacturing, nor does it increase the production cost, and at the same time can achieve high performance and high reliability of the capacitive sensor, and ultra-small package size.
  • each electrode in the fixed electrode assembly may be, for example, all located within the vacuum chamber 4, and in particular, the high bias electrode 6 is located within the vacuum chamber 4.
  • the fixed electrode assembly for example, includes two high bias electrodes 6 with a high voltage V+ and a ground electrode 5 (GND), wherein the ground electrode 5 is arranged between the two high bias electrodes 6.
  • a grounded movable electrode 7 is provided on the diaphragm 3 above the substrate 1, and the movable electrode 7 may, for example, be located together within the vacuum chamber 4 and correspond to the ground electrode 5.
  • the movable electrode 7 may also be embedded in the diaphragm 3 instead of being located in the vacuum chamber 4, as shown in FIG. 7 , and those skilled in the art may adjust the location of the movable electrode 7 on the diaphragm 3 as needed.
  • the movable electrode 7 When a high bias voltage is applied to the high bias electrode 6 in a vacuum environment, the movable electrode 7 will be subjected to an upward electrostatic force in the surrounding electric field, that is, the direction of the electrostatic force is away from the high bias electrode 6 on the substrate 1, so that an electrostatic repulsion force is formed between the diaphragm 3 and each of the high bias electrodes 6, thereby completely eliminating the problem of electrostatic sagging of the diaphragm 3, and preventing the diaphragm 3 from adhering to the substrate 1 under atmospheric pressure.
  • the support column 8 on the diaphragm 3 hits the substrate 1 when it collapses, and the electrostatic repulsion between the diaphragm 3 and the high bias electrode 6 is combined.
  • the diaphragm 3 and the substrate 1 can maintain a certain distance from each other without contacting each other or the gap between them being too small, for example, less than a critical distance, so as to avoid the electrostatic force from forming a downward attraction and causing the diaphragm 3 to adhere to the substrate 1.
  • the diaphragm 3 as a movable component is in an electrostatic suspension state, that is, the static position moves upward (away from the fixed electrode direction), and then the diaphragm 3 can vibrate under the action of sound pressure, and the movable electrode 7 generates a voltage signal during vibration/operation.
  • the sensor chip provided in the embodiment of the present disclosure is a three-terminal device: V+/GND/SENSE.
  • the sensitivity affected by the parasitic capacitance is Soc ⁇ Sm*Ez*Cm/(Cm+Cp), where Sm is the mechanical sensitivity (dw/dp) of the movable electrode 7 on the diaphragm 3, w is the displacement of the diaphragm in the Z-axis direction, p is the sound pressure, Ez is the equivalent Z-direction electric field strength at the diaphragm under bias, Cm is the capacitance of the movable electrode 7 to the high bias electrode 6, and Cp is the parasitic capacitance from the SENSE node to the ground.
  • the vacuum degree of the vacuum chamber 4 is 100Pa-1000Pa.
  • the sensor chip of the disclosed embodiment has a vacuum chamber 4, for example, the vacuum degree of the vacuum chamber 4 is controlled within 100Pa to 1000Pa, and a higher bias voltage such as +100V to +300V can be applied within this vacuum degree range.
  • a high bias voltage can better enhance the electrostatic repulsion. Specifically, the electrostatic repulsion is large and the electric field strength is high, which is conducive to enhancing the sensitivity of the diaphragm without causing the diaphragm to be broken down.
  • the two high bias electrodes 6 are both high voltage electrodes; the applied high bias voltage is +100V to +300V.
  • the fixed electrode component includes two high bias electrodes 6 with a high voltage V+ and a ground electrode 5 (ground GND) located between the two high bias electrodes 6, and a vertical movable component with a grounded potential or close to the ground, namely, the diaphragm 3, is arranged above the plane where the fixed electrode assembly is located.
  • the movable electrode 7 arranged on the diaphragm 3 When a high bias voltage of +100V to +300V is applied to the two high bias electrodes 6 in a vacuum environment, the movable electrode 7 arranged on the diaphragm 3 generates an overall upward net electrostatic force, namely, an electrostatic repulsive force, in the electric field formed around it, which can completely eliminate the problem of electrostatic sedimentation of the diaphragm.
  • the support column 8 is provided in a plurality, and the support column 8 is located in the vacuum chamber 4 , and the plurality of support columns 8 are arranged on the vibrating membrane 3 .
  • One side is set for spacing.
  • each support column 8 can extend into the vacuum chamber 4, and under atmospheric pressure, each support column 8 touches the substrate 1 when following the diaphragm 3 to collapse, and the electrostatic repulsion between the diaphragm 3 and the high bias electrode 6 enables the diaphragm 3 and the substrate 1 to maintain a distance greater than a critical distance, so that the diaphragm 3 and the substrate 1 will not contact each other or the gap between the two will not be too small, so that the electrostatic force between the two can be prevented from forming a downward attractive force and causing the diaphragm 3 to adhere to the substrate 1.
  • the number of the support columns 8 can be reasonably adjusted as needed, and there is no specific limitation on this in the embodiment of the present disclosure.
  • each of the sensing components 2 includes three support columns 8 , one of which corresponds to the position of the ground electrode 5 , and the remaining two support columns 8 are arranged in a one-to-one correspondence with the two high bias electrodes 6 .
  • a supporting column 8 can be provided corresponding to each fixed electrode in the fixed electrode assembly. In this way, it can provide a more stable supporting effect for the diaphragm 3 after it collapses, and can better prevent the diaphragm 3 from sticking to the substrate 1.
  • the sensing component 2 when the sensing component 2 is provided in plurality, the plurality of sensing components 2 are arranged on one side surface of the substrate 1 to form an array of a set shape; wherein the sensing components 2 are provided independently of each other, and the sensing components 2 are connected in parallel.
  • the multiple sensing components 2 are arranged on one side surface of the substrate 1 to form a set array; wherein the vacuum chambers 4 of each sensing component 2 are interconnected.
  • two adjacent sensing components 2 are configured to share the same high bias electrode 6 .
  • a first dielectric layer 9 is disposed on one side of the substrate 1 where the sensing component 2 is disposed, and the ground electrode 5 and the two high bias electrodes 6 are formed on the first dielectric layer 9 .
  • a second dielectric layer 10 is formed on the diaphragm 3 at one side of the vacuum cavity 4 , and the movable electrode 7 is formed on the second dielectric layer 10 .
  • the high bias electrode 6 and the ground electrode 5 are both made of metal materials.
  • the high bias electrode 6 and the ground electrode 5 can be formed by first forming a metal film on the first dielectric layer 9 by deposition, and then forming a set electrode pattern by photolithography and etching.
  • the movable electrode 7 can be first deposited on the second dielectric layer 10 to form a metal film, and then photolithography and etching are performed to form a set electrode pattern.
  • the material of the substrate 1 is, for example, silicon.
  • the first dielectric layer 9 and the second dielectric layer 10 are made of silicon dioxide material, for example.
  • C1 is the total capacitance of the movable electrode 7 per unit length of the sensing component 2, and the main structural dimensions include the width of the high bias electrode 6, which is 2um, the spacing is 2um, and the thickness is 0.5um, and the width of the movable electrode 7 is 0.85um and the thickness is 0.5um.
  • the sensor chip of the disclosed embodiment is designed based on the sensing component 2 including the vacuum chamber 4, which allows the movable electrode 7 and the ground electrode 5 to have a very small gap, because there is no influence of air damping and no hidden danger of air breakdown.
  • the small gap (such as 0.1 to 0.5um) between the movable electrode 7 and the ground electrode 5 can achieve the electrostatic repulsion force to offset the atmospheric pressure, thereby achieving the electrostatic suspension effect of the diaphragm 3.
  • the electrostatic repulsion force is only related to the structure size and the applied bias voltage, and because the signal voltage of the sensor chip (up to the mV level) is much smaller than the high bias voltage (tens or hundreds of volts), this electrostatic repulsion force is always in a stable state during operation, ensuring a linear response under large sound pressure signal conditions.
  • the device performance still needs to correspond to the change in atmospheric pressure (maximum about +/-0.1 atmosphere).
  • one method is to integrate an absolute pressure sensor and feedback the ASIC chip to adjust the bias voltage, but this is not easy to achieve.
  • Another method is to design the diaphragm to have sufficient mechanical strength to cover this range of atmospheric pressure changes, but this will roughly result in the mechanical sensitivity Sm of the diaphragm being about an order of magnitude lower.
  • a method for manufacturing a sensor chip is provided, which can be used to manufacture the above-mentioned sensor chip.
  • the method for manufacturing the sensor chip includes at least the following steps S1 to S9, see FIG6 and FIG7 :
  • Step S1 providing a substrate 1, covering a first dielectric layer 9 on one side of the substrate 1, and forming at least one fixed electrode assembly on the first dielectric layer 9; wherein each of the fixed electrode assemblies comprises two high bias electrodes 6 and a ground electrode 5 between the two high bias electrodes 6;
  • the two high bias electrodes 6 are disposed on both sides of the ground electrode 5.
  • the two high bias electrodes 6 can be symmetrically disposed with respect to the ground electrode 5.
  • one fixed electrode assembly can be arranged on the substrate 1, or two or more fixed electrode assemblies can be arranged as required.
  • the specific arrangement of the fixed electrode assemblies on the substrate 1 can be flexibly adjusted as required.
  • the material of the substrate 1 is, for example, silicon.
  • the first dielectric layer 9 is made of, for example, silicon nitride material doped with polyethylene silicon material by low pressure chemical vapor deposition.
  • Step S2 Covering the side of the substrate 1 where the fixed electrode assembly is provided with a sacrificial layer 18 , forming a blind hole 19 of a set depth on the side of the sacrificial layer 18 away from the substrate 1 , and each fixed electrode corresponds to one blind hole 19 .
  • the sacrificial layer 18 is made of SiO 2 , PSG or BPSG.
  • the blind hole 19 is subsequently used to form a support column, and its depth will determine the height of the formed support column 8.
  • the blind hole 19 can be formed to a set depth by etching, for example.
  • Step S3 Covering the second dielectric layer 10 on one side of the sacrificial layer 18 where the blind hole 19 is provided, the second dielectric layer 10 is also embedded in the blind hole 19 and blocks the blind hole 19 to form a support column 8, and a movable electrode 7 is formed on the second dielectric layer 10, so that the position of the movable electrode 7 corresponds one-to-one to the position of the ground electrode 5.
  • the second dielectric layer 10 and the first dielectric layer 9 may be the same.
  • the second dielectric layer 10 is made of, for example, silicon nitride material doped with polyethylene silicon material by low pressure chemical vapor deposition.
  • each of the fixed electrode assemblies is provided with one movable electrode 7 , and the ground electrode 5 in the fixed electrode assembly and the movable electrode 7 are in a corresponding position.
  • the support column 8 and the movable electrode 7 may be located on the same side of the diaphragm 3 and on one side of the vacuum chamber 4.
  • the movable electrode 7 may also be embedded in the diaphragm 3 instead of being located in the vacuum chamber 4.
  • Step 4 forming first through holes 20 penetrating the sacrificial layer 18 and the second dielectric layer 10 on both sides of each of the fixed electrode assemblies.
  • the first through hole 20 may be formed by, for example, etching.
  • Step 5 Cover the diaphragm 3 on the second dielectric layer 10 and block the first through hole 20 , the movable electrode 7 is fixedly connected to the diaphragm 3 , and a second through hole 21 is formed on the diaphragm 3 and the second dielectric layer 10 .
  • the diaphragm 3 is, for example, a silicon nitride layer deposited on the second dielectric layer 10 by using a low pressure chemical vapor deposition method.
  • the second through hole 21 can be formed, for example, by etching on the diaphragm 3 and the second dielectric layer 10 .
  • Step 6 remove the sacrificial layer 18 between two adjacent first through holes 20 to form a cavity 24 , encapsulate at least the fixed electrode assembly and the support column 8 in the cavity 24 , and the second through hole 21 is connected to the cavity 24 .
  • the sacrificial layer 18 may be removed by any one of HF, VHF, and BHF/BOE.
  • Step 7 The second through hole 21 is sealed, and the cavity 24 is made to have a set vacuum degree to form a vacuum cavity 4 .
  • low temperature deposited polycarbonate HDPCVD, PVD, etc. are used.
  • the vacuum degree in the vacuum chamber 4 is 100Pa-1000Pa.
  • Step 8 Provide a conductive through hole 22 at the edge of the substrate 1, wherein the conductive through hole 22 penetrates the sacrificial layer 18, the second dielectric layer 10 and the diaphragm 3, and the conductive through hole 22 One end of is electrically connected to the high bias electrode 6.
  • Step 9 An electrical connection portion 23 is provided at the other end of the conductive through hole 22 , and the electrical connection portion 23 is arranged on the surface of the diaphragm 3 .
  • the electrical connection portion is, for example, a solder pad.
  • the step of fixedly connecting the diaphragm 3 and the movable electrode 7 includes: connecting the movable electrode 7 to the side of the diaphragm 3 located at the vacuum chamber 4 so that the movable electrode 7 is located inside the vacuum chamber 4; or, embedding the movable electrode 7 in the diaphragm 3 so that the movable electrode 7 is located outside the vacuum chamber 4.
  • a capacitive sensor comprises: a packaging structure and the sensor chip as described above, wherein the sensor chip is disposed in the packaging structure.
  • the packaging structure includes a circuit board 11 and a packaging layer 12 disposed on one side of the circuit board 11 , the sensor chip is disposed on the circuit board 11 , and the packaging layer 12 is disposed around the outer periphery of the sensor chip.
  • a temporary protection layer 13 is covered on the sensor chip.
  • the above example shows a small-sized capacitive sensor.
  • a photoresist or temporary protective layer 13 of a set thickness is first patterned on the sensor chip. After the MEMS chip and ASIC chip are die-bonded and wire-bonded to the circuit board 11, thermosetting resin is hot-pressed by selective over molding or transfer molding to complete the plastic packaging, which has the advantages of small size, low cost, high reliability, etc.
  • a plastic packaged device is shown after the temporary protective layer 13 or the photoresist is removed.
  • Such a packaged device has an ultra-small size, ultra-low packaging cost, ultra-high reliability, and excellent performance such as high SNR, high AOP, etc.).
  • the packaging structure includes a circuit board 11 and a shell 14 arranged on one side of the circuit board 11, and the circuit board 11 and the shell 14 enclose a receiving cavity 15; the sensor chip is located in the receiving cavity 15 and is fixedly arranged on the circuit board 11, and an ASIC chip 16 is also arranged on the circuit board 11; a sound hole 17 connected to the outside is opened on the shell 14 or the circuit board 11.
  • the sensor chip may also be packaged between the circuit board and the housing. The difference is that since the MEMS chip does not require a large acoustic back cavity, the device performance is not affected by the packaging.
  • An embodiment of the present disclosure further provides an electronic device, which includes the capacitive sensor as described above.
  • the capacitive sensor can be used in a sound-generating device, and can also be used in a mechanical sensor.
  • the electronic devices include but are not limited to smart phones, tablet computers, laptop computers, smart wearable devices, etc., and the present disclosure does not impose any restrictions on this.

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Abstract

本申请公开了一种传感器芯片及其制作方法、电容传感器和电子设备；传感器芯片包括衬底及设于衬底上的感应组件，感应组件包括振膜、固定电极组件及可动电极，振膜支撑在衬底的一侧并与衬底围合成真空腔；固定电极组件包括两个高偏压电极及接地电极，接地电极与两个高偏压电极均设于衬底上并位于真空腔一侧，可动电极设于振膜，可作为检测节点虚拟接地，与接地电极相对；在振膜位于真空腔的一侧设有支撑柱，支撑柱在大气压力下能使振膜与高偏压电极之间的距离大于临界距离；在施加高偏压下，可动电极与高偏压电极之间形成静电排斥力，振膜与可动电极在所述静电排斥力下可产生朝向背离高偏压电极的方向移动，可动电极在工作时产生交流信号输出电压。图1为摘要附图

Description

传感器芯片及其制作方法、电容传感器和电子设备
本公开要求于2022年11月21日提交中国专利局，申请号为202211455649.3，申请名称为“传感器芯片及其制作方法、电容传感器和电子设备”的中国专利申请的优先权，其全部内容通过引用结合在本公开中。
技术领域
本公开涉及传感器技术领域，更具体地，本公开涉及一种传感器芯片及其制作方法、电容传感器和电子设备。
背景技术
现有技术中，在具有高电压V+、地GND、高压V+固定电极条的平面上方设置电位接地或近地的垂直可动部件，电场在可动部件周围不均匀，在临界位置点以上可以产生对可动部件总体向上的静电排斥力，从而消除静电下榻的问题。然而，在可靠性试验或者日常使用中却发现，由于应用的是电场的非线性/不均匀性，在Z轴方向上电场分量在振膜处较小，所以需要高一个数量级的偏压即高偏压才能达到同样的灵敏度，但这对空气中工作的小尺寸压电换能器挑战很高，在开放的应用环境下，会出现空气击穿振膜或者振膜的性能稳定性没有保障，从而导致产品的性能降低甚至失效。
发明内容
本公开的目的在于提供的一种传感器芯片及其制作方法、电容传感器和电子设备的新技术方案。
第一方面，本公开实施例提供了一种传感器芯片。所述传感器芯片包括衬底及设于所述衬底上的至少一个感应组件，所述感应组件包括振膜、固定电极组件及可动电极，所述振膜支撑在所述衬底的一侧并与所述衬底 围合成真空腔；
所述固定电极组件包括三个固定电极，所述三个固定电极包括两个高偏压电极及介于该两个高偏压电极之间的接地电极，所述接地电极与所述两个高偏压电极均设于所述衬底上并位于所述真空腔一侧，所述可动电极设于所述振膜，所述可动电极被配置为用作为检测节点，直流电位虚拟接地，且所述可动电极与所述接地电极的位置相对；
在所述振膜位于所述真空腔的一侧设有支撑柱，所述支撑柱被配置为在大气压力下能使所述振膜与所述高偏压电极之间的距离大于临界距离；
在施加高偏压的状态下，所述可动电极在电场中受到的静电力朝向背离所述高偏压电极的方向，所述可动电极与所述高偏压电极之间形成静电排斥力，所述振膜与所述可动电极在所述静电排斥力下可产生朝向背离所述高偏压电极的方向移动，所述可动电极在工作时产生交流信号输出电压。
可选地，所述真空腔的真空度为100Pa～1000Pa。
可选地，对所述两个高偏压电极施加的所述高偏压为+100V～+300V。
可选地，所述支撑柱设置为多个，所述支撑柱位于所述真空腔之内，且多个所述支撑柱在所述振膜的一侧为间隔设置。
可选地，每个所述感应组件包括三个支撑柱，其中的一个所述支撑柱与所述接地电极的位置相对应，其余的两个所述支撑柱与所述两个高偏压电极为一一对应设置。
可选地，当所述感应组件设置为多个时，多个所述感应组件在所述衬底的一侧表面上排列形成设定形状的阵列；其中，各所述感应组件为相互独立设置，且各所述感应组件之间为并联连接。
可选地，当所述感应组件设置为多个时，多个所述感应组件在所述衬底的一侧表面上排列形成设定阵列；其中，各所述感应组件的所述真空腔之间相互连通。
可选地，相邻的两个所述感应组件被配置为能够共用同一个所述高偏压电极。
可选地，在所述衬底设置所述感应组件的一侧设置有第一介质层，所述接地电极及所述两个高偏压电极均形成在所述第一介质层上；
且/或
在所述振膜上位于所述真空腔一侧形成有第二介质层，所述可动电极形成在所述第二介质层上。
可选地，所述可动电极与所述支撑柱位于所述振膜的同一侧，并所述真空腔之内；或者，所述可动电极嵌设于所述振膜内，且所述可动电极位于所述真空腔之外。
第二方面，本公开实施例提供了一种如第一方面所述的传感器芯片的制作方法。所述制作方法包括：
在所述衬底的一侧覆盖第一介质层，在所述第一介质层上形成至少一个固定电极组件；其中，每个所述固定电极组件包括三个固定电极，所述三个固定电极包括两个高偏压电极及介于该两个高偏压电极之间的接地电极；
在所述衬底设有所述固定电极组件的一侧覆盖牺牲层，在所述牺牲层背离所述衬底的一侧形成设定深度的盲孔，每个所述固定电极对应一个所述盲孔；
在所述牺牲层设有所述盲孔的一侧覆盖第二介质层，所述第二介质层还嵌入所述盲孔内并封堵住所述盲孔以形成支撑柱，在所述第二介质层上形成有可动电极，使所述可动电极的位置与所述接地电极的位置为一一对应；
在每个所述固定电极组件的两侧分别形成贯通所述牺牲层和所述第二介质层的第一通孔；
在所述第二介质层上覆盖振膜，并封堵住所述第一通孔，所述可动电极与所述振膜固定连接，并在所述振膜及所述第二介质层上形成第二通孔；
去除相邻的两个所述第一通孔之间的所述牺牲层形成空腔，至少将所述固定电极组件及支撑柱封装在空腔内，所述第二通孔与所述空腔连通；
封堵住所述第二通孔，并使所述空腔具有设定真空度以形成真空腔；
在所述衬底的边缘设置导电通孔，所述导电通孔贯穿所述牺牲层、所述第二介质层及所述振膜，并使所述导电通孔的一端与所述高偏压电极电连接；
在所述导电通孔的另一端设置电连接部，将所述电连接部布设于所述振膜的表面。
可选地，在所述振膜与所述可动电极固定连接的步骤中，包括：
将所述所述可动电极连接在所述振膜位于所述真空腔的一侧，以使所述可动电极位于所述真空腔之内；或者，将所述可动电极嵌设于所述振膜内，使所述可动电极位于所述真空腔之外。
第三方面、本公开实施例提供了一种电容传感器。所述电容传感器包括：
电容传感器，其特征在于，包括：
封装结构；及
如第一方面所述的传感器芯片，所述传感器芯片设置于所述封装结构内。
可选地，所述封装结构包括电路板及设置于所述电路板一侧的封装层，所述传感器芯片设于所述电路板，且所述封装层围设在所述传感器芯片的外周侧。
可选地，在所述传感器芯片上覆盖有临时保护层。
可选地，所述封装结构包括电路板及设置于所述电路板一侧的外壳，所述电路板与所述外壳围合形成容置腔；
所述传感器芯片位于所述容置腔之内，并固定设置在所述电路板上，在所述电路板上还设置有ASIC芯片；
所述外壳或者所述电路板上开设有与外部连通的声孔。
第四方面，本公开实施例提供了一种电子设备。所述电子设备包括如第三方面所述的电容传感器。
本公开的有益效果在于：
本公开实施例提供了一种传感器芯片的方案，在衬底上设置了真空密封腔的结构，同时还引入静电排斥作用，使得高偏压一直处于真空密封环境中，这可以消除空气击穿振膜的情况发生；同时，通过产生的静电排斥力来抵消全部或部分大气压，使得振膜可以被设计得更加柔软，这利于提升振膜的机械灵敏度，从而使形成的传感器芯片的灵敏度得到提升。
通过以下参照附图对本公开的示例性实施例的详细描述，本公开的其它特征及其优点将会变得清楚。
附图说明
被结合在说明书中并构成说明书的一部分的附图示出了本公开的实施例，并且连同其说明一起用于解释本公开的原理。
图1是本公开实施例的传感器芯片的结构示意图之一；
图2是本公开实施例的传感器芯片的结构示意图之二；
图3是本公开实施例的传感器芯片的结构示意图之三；
图4是本公开实施例的传感器芯片的结构示意图之四；
图5是本公开实施例中感应组件的FEM仿真结果示意图；
图6是本公开实施例的传感器芯片的制作方法流程示意图之一；
图7是本公开实施例的传感器芯片的制作方法流程示意图之二；
图8是本公开实施例的电容传感器的结构示意图之一；
图9是本公开实施例的电容传感器的结构示意图之二；
图10是本公开实施例的电容传感器的结构示意图之三。
附图标记说明：
1、衬底；2、感应组件；3、振膜；4、真空腔；5、接地电极；6、高
偏压电极；7、可动电极；8、支撑柱；9、第一介质层；10、第二介质层；11、电路板；12、封装层；13、临时保护层；14、外壳；15、容置腔；16、ASIC芯片；17、声孔；18、牺牲层；19、盲孔；20、第一通孔；21、第二通孔；22、导电通孔；23、电连接部；24、空腔。
具体实施方式
现在将参照附图来详细描述本公开的各种示例性实施例。应注意到：除非另外具体说明，否则在这些实施例中阐述的部件和步骤的相对布置、数字表达式和数值不限制本公开的范围。
以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本公开及其应用或使用的任何限制。
对于相关领域普通技术人员已知的技术、方法和设备可能不作详细讨论，但在适当情况下，所述技术、方法和设备应当被视为说明书的一部分。
在这里示出和讨论的所有例子中，任何具体值应被解释为仅仅是示例性的，而不是作为限制。因此，示例性实施例的其它例子可以具有不同的值。
应注意到：相似的标号和字母在下面的附图中表示类似项，因此，一旦某一项在一个附图中被定义，则在随后的附图中不需要对其进行进一步讨论。
下面结合附图对本公开实施例提供的传感器芯片及其制作方法、电容传感器和电子设备分别进行详细地描述。
根据本公开实施例的一个方面，提供了一种传感器芯片，其可应用于例如电容式麦克风、电容式绝对压力传感器等微机电系统器件中。
微机电系统MEMS技术是将微电子技术与微机械工程融合到一起的工业技术。微机电系统器件的尺寸通常小于几毫米，它的内部结构一般在微米甚至纳米量级。
本公开实施例提供的传感器芯片例如还可以应用于诸如力学传感器中。力学传感器能够检测力学作用导致的变化的传感器。例如，这里的力学作用包括声压、气压、加速度、由于温度变化产生的应力所产导致的形变、由于湿度变化产生的应力所导致的形变等。
本公开实施例提供的传感器芯片，参见图1，所述传感器芯片包括衬底1及设于所述衬底1上的至少一个感应组件2，所述感应组件2包括振膜3、固定电极组件及可动电极7，所述振膜3支撑在所述衬底1的一侧并与所述衬底1围合成真空腔4；
所述固定电极组件包括三个固定电极，所述三个固定电极包括两个高偏压电极6及介于该两个高偏压电极6之间的接地电极5，所述接地电极5与所述两个高偏压电极6均设于所述衬底1上并位于所述真空腔4一侧，所述可动电极7设于所述振膜3，所述可动电极7被配置为用作为检测节点，直流电位虚拟接地，且所述可动电极7与所述接地电极5的位置相对；
在所述振膜3位于所述真空腔4的一侧设有支撑柱8，所述支撑柱8 被配置为在大气压力下能使所述振膜3与所述高偏压电极6之间的距离大于临界距离；
在施加高偏压的状态下，所述可动电极7在电场中受到的静电力朝向背离所述高偏压电极6的方向，所述可动电极7与所述高偏压电极6之间形成静电排斥力，所述振膜3与所述可动电极7在所述静电排斥力下可产生朝向背离所述高偏压电极6的方向移动，所述可动电极7在工作时产生交流信号输出电压。
本公开实施例提供的传感器芯片，其为一种具有真空腔4的感应组件，所述感应组件2中的所述振膜3在能够抵抗大气压、防止静电下榻的同时，还能够兼具较好的柔软度，这使得整个所述传感器芯片的灵敏度和信噪比得到了良好的改善。
需要说明的是，现有的APS传感器(Absolute Pressure Sensing传感器，即具有真空密封腔的传感器)，虽然可以提升灵敏度，但考虑到空气中大气压的变化问题，静电下榻的问题很难直接在传感器的设计方面彻底避免。此外，在现有技术中还提出了利用永磁体薄膜磁悬浮的方式来抵抗大气压、防止静电下榻问题，其中振膜可以设计的软一些，但是该方案中需要引进特殊的磁性材料，对量产性以及成本和良率等都是很大的挑战。
本公开实施例提供的传感器芯片，通过在感应组件2中设计包含真空腔4，同时引入静电排斥作用，使得施加的高偏压一直处于真空密封环境(因为高偏压电极6位于真空腔4)中，如此可以消除空气击穿振膜的情况发生；同时，通过静电排斥力来抵消全部或者部分大气压，使得其中的振膜3能够被设计得更加柔软(也即硬度低)，这利于提升所述振膜3的机械灵敏度，从而使形成的传感器芯片的灵敏度和信噪比得到很好的改善。
需要说明的是，基于电容极板间静电吸引的原理，传统的电容结构无论是双电极(单背极)还是三电极(差分)，都无法避免出现静电下榻(Pull-in)的问题，这限制了可动部件(振膜)的运动范围及器件的动态范围，也限制了工作偏压即灵敏度或信噪比。调高偏压的方式在近年来得到了应用。但由于在提高偏压后，除了上述传统电容式麦克风的可靠性问题外，器件还出现了空气击穿振膜的难题(因为需要约数百伏才能得到匹 配的灵敏度)，使得整个传感器的可靠性进一步降低。
本公开实施例提供的传感器芯片，在APS电容结构中引进静电排斥的机制，使得高偏压处于真空(或干燥的高介电强度气体)密封环境之中，如此能够消除空气击穿振膜的问题；同时，静电排斥力抵消全部或部分大气压，所述振膜3就可以设计得较为柔软。其中，所述振膜3的柔软性与其机械灵敏度相关。
具体而言，所述振膜3的机械灵敏度Sm满足：Sm＝dw/dp，其中，w、p分别为振膜位移和声压力。在本公开的实施例中，所述振膜3的机械灵敏度较高，使得形成的传感器芯片或者包含该传感器芯片的电容传感器的灵敏度Soc～Sm*Vb/Gap可以相对较高，但并不会增加工艺制作难度，也就不会增加生产成本，同时能实现电容传感器的高性能和高可靠性，及超小封装尺寸。
在本公开的一个实施例中，参见图1，在所述衬底1上位于所述真空腔4的一侧设置有至少一个固定电极组件，所述固定电极组件中的各个电极例如可以全部位于所述真空腔4之内，特别是高偏压电极6位于真空腔4之内。所述固定电极组件例如包括具有高电压V+的两个高偏压电极6及接地电极5(GND)，其中，所述接地电极5布设在所述两个高偏压电极6之间。在所述衬底1上方的振膜3上设置有接地的可动电极7，所述可动电极7例如可以一同位于所述真空腔4之内，并与所述接地电极5相对应。
可选的是，所述可动电极7也可以嵌设于所述振膜3内，而不位于所述真空腔4之内，参见图7所示，本领域技术人员可以根据需要对所述可动电极7在振膜3上的设置位置进行调整。
当在真空环境中为所述高偏压电极6施加高偏压时，所述可动电极7在周围的电场中会受到向上的静电力，也即静电力的方向背离所述衬底1上的所述高偏压电极6，使得所述振膜3与各所述高偏压电极6之间形成了一种静电排斥力，从而能够彻底消除了振膜3静电下榻的问题，也即可以避免所述振膜3在大气压力下粘附在所述衬底1上。
特别的是，在大气压下，位于所述振膜3上的所述支撑柱8下榻时碰到所述衬底1，加之所述振膜3与所述高偏压电极6之间的静电排斥力， 使得所述振膜3与所述衬底1之间能够保持一定的间距，而不会出现相互接触或者二者之间的间隙过小，例如小于临界距离。避免静电力形成向下的吸引力而造成所述振膜3粘附在所述衬底1上。
在本公开的实施例中，当为传感器芯片上的高偏压电极6施加高偏压之后，所述振膜3作为可动部件处于静电悬浮状态，即静态位置上移(远离固定电极方向)，然后在声压作用下振膜3可以产生振动，可动电极7在振动/工作中产生电压信号。
本公开实施例提供的传感器芯片为一个三端器件：V+/GND/SENSE。寄生电容影响的灵敏度为Soc～Sm*Ez*Cm/(Cm+Cp)，其中，Sm为振膜3上可动电极7的机械灵敏度(dw/dp)，w为Z轴方向振膜位移、p为声压，Ez为偏压下振膜处等效的Z向电场强度，Cm为可动电极7对高偏压电极6的电容，Cp为SENSE节点到地的寄生电容。
在本公开的一些示例中，所述真空腔4的真空度为100Pa～1000Pa。
本公开实施例的传感器芯片具有真空腔4，例如将该真空腔4的真空度例如控制在100Pa～1000Pa，在这一真空度范围内可以施加较高的偏压例如+100V～+300V。采用高偏压可以更好的提升静电排斥力。具体地，静电排斥力大、电场强度高，利于提升振膜的灵敏度且不会造成振膜被击穿的情况。
在本公开的一些示例中，所述两个高偏压电极6均为高压电极；施加的所述高偏压为+100V～+300V。
在所述衬底1上，以设置一个所述感应组件2为例，其中所述固定电极组件包括两个高电压V+的高偏压电极6及位于该两个高偏压电极6之间的接地电极5(地GND)，在所述固定电极组件所在平面的上方设置有电位接地或者近地的垂直可动部件即所述振膜3，当两个所述高偏压电极6在真空环境中被施加+100V～+300V的高偏压时，所述振膜3上设置的所述可动电极7在周围形成的电场中产生总体向上的净静电力也即静电排斥力，这就能够彻底消除振膜的静电下榻的问题。
在本公开的一些示例中，参见图1，所述支撑柱8设置为多个，所述支撑柱8均位于所述真空腔4之内，且多个所述支撑柱8在所述振膜3的 一侧为间隔设置。
参见图1，在所述振膜3上还设置有多个所述支撑柱8。具体地，各所述支撑柱8可以伸入所述真空腔4之内，在大气压下，各所述支撑柱8在跟随所述振膜3下榻时碰到所述衬底1，加之所述振膜3与所述高偏压电极6之间的静电排斥力，使得所述振膜3与所述衬底1之间能够保持大于临界距离的状态，这样使得所述振膜3与所述衬底1之间不会相互接触或者二者之间的间隙不会过小，这样，就可以避免二者之间的静电力形成向下的吸引力而造成所述振膜3粘附在所述衬底1上。
需要说明的是，所述支撑柱8的设置数量可以根据需要合理调整，本公开实施例中对此不做具体限制。
例如，参见图1，每个所述感应组件2包括三个支撑柱8，其中的一个所述支撑柱8与所述接地电极5的位置相对应，其余的两个所述支撑柱8与所述两个高偏压电极6为一一对应设置。
也就是说，对于各所述感应组件2来说，可以为所述固定电极组件中的每个固定电极对应的设置一个所述支撑柱8，这样，可以对所述振膜3下榻后起到更稳定的支撑作用，能更好的防止所述振膜3贴合在所述衬底1上。
在本公开的一些示例中，参见图2，当所述感应组件2设置为多个时，多个所述感应组件2在所述衬底1的一侧表面上排列形成设定形状的阵列；其中，各所述感应组件2为相互独立设置，且各所述感应组件2之间为并联连接。
在本公开的一些示例中，参见图3，当所述感应组件2设置为多个时，多个所述感应组件2在所述衬底1的一侧表面上排列形成设定阵列；其中，各所述感应组件2的所述真空腔4之间相互连通。
可选的是，参见图4，相邻的两个所述感应组件2被配置为能够共用同一个所述高偏压电极6。
在本公开的一些示例中，参见图6，在所述衬底1设置所述感应组件2的一侧设置有第一介质层9，所述接地电极5及所述两个高偏压电极6均形成在所述第一介质层9上。
在本公开的一些示例中，参见图6，在所述振膜3上位于所述真空腔4一侧形成有第二介质层10，所述可动电极7形成在所述第二介质层10上。
其中，所述高偏压电极6及所述接地电极5均为金属材料。
例如，所述高偏压电极6及所述接地电极5可以通过沉积的方式在所述第一介质层9上先形成金属薄膜，之后通过光刻、蚀刻形成设定电极图案。
同样地，所述可动电极7可以采用先沉积在第二介质层10上形成金属薄膜，再经光刻、刻蚀形成设定电极图案。
其中，所述衬底1的材料例如为硅。
其中，所述第一介质层9及所述第二介质层10例如为二氧化硅材料。
参见图5，图5示出了感应组件2的FEM仿真结果。其中，C1是单位长度的感应组件2内的可动电极7的总电容，主要结构尺寸包括高偏压电极6的宽度2um、间距2um、厚度0.5um，可动电极7的宽度0.85um、厚度0.5um。此结构在该偏压V＝+300V时，可产生超过1个大气压的等效静电排斥压力Pes，在仿真范围内，可动电极7和接地电极5之间的间距Gap越小，则此等效静电排斥压力Pes越大。
本公开实施例的传感器芯片，基于包含真空腔4的感应组件2设计，可以允许所述可动电极7与所述接地电极5具有很小的间距Gap，因为没有空气阻尼的影响，也没有空气击穿的隐患。当传感器芯片的横向尺寸足够小时(比如微米、亚微米级)，所述可动电极7与所述接地电极5之间的小间距Gap(如0.1～0.5um)可以做到静电排斥力抵消大气压力，从而实现所述振膜3的静电悬浮效果。
需要说明的是，静电排斥力仅与结构尺寸和所施加的偏压相关，而且因为传感器芯片的信号电压(最高mV量级)远远小于高偏压(数十、上百伏)，所以此静电排斥力在工作中一直处于稳定状态，保证大声压信号状态下的线性响应。
除此之外，当包含传感器芯片和ASIC芯片的封装器件完成校准后，器件性能仍然需要对应大气压的变化(最大约+/-0.1个大气压)。目前一个方法是集成绝对压力传感器并反馈ASIC芯片调整偏压，但这不容易实现。 另一个方法就是设计振膜机械强度足够大、能够覆盖此大气压变化范围，但是这大致会导致振膜的机械灵敏度Sm低一个数量级左右。
根据本公开实施例的另一方面，提供了一种传感器芯片的制作方法，能够用于制作出上述的传感器芯片。
在本公开的实施例中，所述传感器芯片的制作方法至少包括如下的步骤S1至步骤S9，参见图6及图7：
步骤S1：提供一衬底1，在所述衬底1的一侧覆盖第一介质层9，在所述第一介质层9上形成至少一个固定电极组件；其中，每个所述固定电极组件包括两个高偏压电极6及介于该两个高偏压电极6之间的接地电极5；
其中，所述两个高偏压电极6分设所述接地电极5的两侧。例如，所述两个高偏压电极6可以关于所述接地电极5呈对称设置。
其中，在所述衬底1上可以设置一个所述固定电极组件，也可以根据需要设置两个或者两个以上的所述固定电极组件。可选的是，所述固定电极组件在衬底1上的具体排布方式可以根据需要灵活进行调整。
其中，所述衬底1的材料例如为硅。
其中，所述第一介质层9例如采用低压力化学气相沉积法在氮化硅材料中掺杂聚乙烯硅材料制成。
步骤S2：在所述衬底1设有所述固定电极组件的一侧覆盖牺牲层18，在所述牺牲层18背离所述衬底1的一侧形成设定深度的盲孔19，每个所述固定电极对应着一个所述盲孔19。
其中，所述牺牲层18的材质为SiO2、PSG或BPSG。
其中，所述盲孔19后续用于形成支撑柱，其深度将决定形成的支撑柱8的高度。所述盲孔19例如可以通过刻蚀的方式形成设定深度。
步骤S3：在所述牺牲层18设有所述盲孔19的一侧覆盖第二介质层10，所述第二介质层10还嵌入所述盲孔19内并封堵住所述盲孔19以形成支撑柱8，在所述第二介质层10上形成有可动电极7，使所述可动电极7的位置与所述接地电极5的位置为一一对应。
其中，所述第二介质层10与所述第一介质层9可以相同。
具体地，所述第二介质层10例如采用低压力化学气相沉积法在氮化硅材料中掺杂聚乙烯硅材料制成。
需要说明的是，每个所述固定电极组件配设一个所述可动电极7，并使该固定电极组件中的接地电极5与该可动电极7的位置形成对应关系。
可选的是，所述支撑柱8与所述可动电极7可以位于所述振膜3的同一侧并位于所述真空腔4的一侧。当然，所述可动电极7也可以不位于所述真空腔4之内而嵌设于所述振膜3内。
步骤4：在每个所述固定电极组件的两侧分别形成贯通所述牺牲层18和所述第二介质层10的第一通孔20。
形成所述第一通孔20的方式例如可以通过刻蚀的方式。
步骤5：在所述第二介质层10上覆盖振膜3，并封堵住所述第一通孔20，所述可动电极7与所述振膜3固定连接，并在所述振膜3及所述第二介质层10上形成第二通孔21。
其中，所述振膜3例如为采用低压力化学气相沉积法在所述第二介质层10上沉积形成的氮化硅层。
其中，所述第二通孔21例如可以通过在所述振膜3及所述第二介质层10上刻蚀形成。
步骤6：去除相邻的两个所述第一通孔20之间的所述牺牲层18形成空腔24，至少将所述固定电极组件和所述支撑柱8封装在空腔24，所述第二通孔21与所述空腔24连通。
可选的是，可通过HF、VHF、BHF/BOE中的任一种方式去除所述牺牲层18。
步骤7：封堵住所述第二通孔21，并使所述空腔24具有设定真空度形成真空腔4。
其中，在对所述第二通孔21进行密封时，例如采用低温沉积聚碳酸酯、HDPCVD、PVD等。
其中，所述真空腔4内真空度为100Pa～1000Pa。
步骤8：在所述衬底1的边缘设置导电通孔22，所述导电通孔22贯穿所述牺牲层18、所述第二介质层10及所述振膜3，并使所述导电通孔22 的一端与所述高偏压电极6电连接。
步骤9：在所述导电通孔22的另一端设置电连接部23，将所述电连接部23布设于所述振膜3的表面。
其中，所述电连接部例如为焊盘。
在本公开的一些示例中，在所述振膜3与所述可动电极7固定连接的步骤中，包括：将所述所述可动电极7连接在所述振膜3位于所述真空腔4的一侧，以使所述可动电极7位于所述真空腔4之内；或者，将所述可动电极7嵌设于所述振膜3内，使所述可动电极7位于所述真空腔4之外。
根据本公开实施例的第三方面，提供了一种电容传感器，参见图8至图10，所述电容传感器包括：封装结构及如上述所述的传感器芯片，所述传感器芯片设置于所述封装结构内。
在本公开的一些示例中，参见图8及图9，所述封装结构包括电路板11及设置于所述电路板11一侧的封装层12，所述传感器芯片设于所述电路板11，且所述封装层12围设在所述传感器芯片的外周侧。
可选的是，在所述传感器芯片上覆盖有临时保护层13。
上述示例示出的一种小尺寸的电容传感器。
参见图8，在所述传感器芯片上先图形化一层设定厚度的光刻胶或临时保护层13。在将MEMS芯片及ASIC芯片固晶(DieBond)、打线(Wire-bond)到所述电路板11后，通过Selective Over Molding或Transfer Molding等技术热压热固性树脂以完成塑封，具有尺寸小、成本低、高可靠性等优势。
参见图9，示出了去除临时保护层13或者光刻胶后的塑封器件。这样的封装器件具有超小的尺寸、超低的封装成本、超高的可靠性、以及优良的性能如高SNR、高AOP等)。
在本公开的一些示例中，所述封装结构包括电路板11及设置于所述电路板11一侧的外壳14，所述电路板11与所述外壳14围合形成容置腔15；所述传感器芯片位于所述容置腔15之内，并固定设置在所述电路板11上，在所述电路板11上还设置有ASIC芯片16；所述外壳14或者所述电路板11上开设有与外部连通的声孔17。
参见图10，所述传感器芯片也可以封装在电路板与外壳之间，不同的是，因为MEMS芯片不需要声学大背腔，故器件性能不受封装影响。
本公开实施例还提供了一种电子设备，所述电子设备包括如上述所述的电容传感器。
所述电容传感器可应用发声装置中，也可应用于力学传感器中。
所述电子设备包括但不限于智能手机、平板电脑、笔记本电脑，智能可穿戴设备等，本公开对此不做限制。
上文实施例中重点描述的是各个实施例之间的不同，各个实施例之间不同的优化特征只要不矛盾，均可以组合形成更优的实施例，考虑到行文简洁，在此则不再赘述。
虽然已经通过示例对本公开的一些特定实施例进行了详细说明，但是本领域的技术人员应该理解，以上示例仅是为了进行说明，而不是为了限制本公开的范围。本领域的技术人员应该理解，可在不脱离本公开的范围和精神的情况下，对以上实施例进行修改。本公开的范围由所附权利要求来限定。

Claims (17)

  1. 一种传感器芯片，其特征在于，包括衬底(1)及设于所述衬底(1)上的至少一个感应组件(2)，所述感应组件(2)包括振膜(3)、固定电极组件及可动电极(7)，所述振膜(3)支撑在所述衬底(1)的一侧并与所述衬底(1)围合成真空腔(4)；
    所述固定电极组件包括三个固定电极，所述三个固定电极包括两个高偏压电极(6)及介于该两个高偏压电极(6)之间的接地电极(5)，所述接地电极(5)与所述两个高偏压电极(6)均设于所述衬底(1)上并位于所述真空腔(4)一侧，所述可动电极(7)设于所述振膜(3)，所述可动电极(7)被配置为用作为检测节点，直流电位虚拟接地，且所述可动电极(7)与所述接地电极(5)的位置相对；
    在所述振膜(3)位于所述真空腔(4)的一侧设有支撑柱(8)，所述支撑柱(8)被配置为在大气压力下能使所述振膜(3)与所述高偏压电极(6)之间的距离大于临界距离；
    在施加高偏压的状态下，所述可动电极(7)在电场中受到的静电力朝向背离所述高偏压电极(6)的方向，所述可动电极(7)与所述高偏压电极(6)之间形成静电排斥力，所述振膜(3)与所述可动电极(7)在所述静电排斥力下可产生朝向背离所述高偏压电极(6)的方向移动，所述可动电极(7)在工作时产生交流信号输出电压。
  2. 根据权利要求1所述的传感器芯片，其特征在于，所述真空腔(4)的真空度为100Pa～1000Pa。
  3. 根据权利要求1所述的传感器芯片，其特征在于，对所述两个高偏压电极(6)施加的所述高偏压为+100V～+300V。
  4. 根据权利要求1所述的传感器芯片，其特征在于，所述支撑柱(8)设置为多个，所述支撑柱(8)位于所述真空腔(4)之内，且多个所述支 撑柱(8)在所述振膜(3)的一侧为间隔设置。
  5. 根据权利要求4所述的传感器芯片，其特征在于，每个所述感应组件(2)包括三个支撑柱(8)，其中的一个所述支撑柱(8)与所述接地电极(5)的位置相对应，其余的两个所述支撑柱(8)与所述两个高偏压电极(6)为一一对应设置。
  6. 根据权利要求1所述的传感器芯片，其特征在于，当所述感应组件(2)设置为多个时，多个所述感应组件(2)在所述衬底(1)的一侧表面上排列形成设定形状的阵列；其中，各所述感应组件(2)为相互独立设置，且各所述感应组件(2)之间为并联连接。
  7. 根据权利要求1所述的传感器芯片，其特征在于，当所述感应组件(2)设置为多个时，多个所述感应组件(2)在所述衬底(1)的一侧表面上排列形成设定阵列；其中，各所述感应组件(2)的所述真空腔(4)之间相互连通。
  8. 根据权利要求7所述的传感器芯片，其特征在于，相邻的两个所述感应组件(2)被配置为能够共用同一个所述高偏压电极(6)。
  9. 根据权利要求1所述的传感器芯片，其特征在于，在所述衬底(1)设置所述感应组件(2)的一侧设置有第一介质层(9)，所述接地电极(5)及所述两个高偏压电极(6)均形成在所述第一介质层(9)上；
    且/或
    在所述振膜(3)上位于所述真空腔(4)一侧形成有第二介质层(10)，所述可动电极(7)形成在所述第二介质层(10)上。
  10. 根据权利要求1所述的传感器芯片，其特征在于，所述可动电极(7)与所述支撑柱(8)位于所述振膜(3)的同一侧，并所述真空腔(4)之内；
    或者，
    所述可动电极(7)嵌设于所述振膜(3)内，且所述可动电极(7)位于所述真空腔(4)之外。
  11. 一种如权利要求1-10中任一项所述的传感器芯片的制作方法，其特征在于，所述制作方法包括：
    在所述衬底(1)的一侧覆盖第一介质层(9)，在所述第一介质层(9)上形成至少一个固定电极组件；其中，每个所述固定电极组件包括三个固定电极，所述三个固定电极包括两个高偏压电极(6)及介于该两个高偏压电极(6)之间的接地电极(5)；
    在所述衬底(1)设有所述固定电极组件的一侧覆盖牺牲层(18)，在所述牺牲层(18)背离所述衬底(1)的一侧形成设定深度的盲孔(19)，每个所述固定电极对应一个所述盲孔(19)；
    在所述牺牲层(18)设有所述盲孔(19)的一侧覆盖第二介质层(10)，所述第二介质层(10)还嵌入所述盲孔(19)内并封堵住所述盲孔(19)以形成支撑柱(8)，在所述第二介质层(10)上形成有可动电极(7)，使所述可动电极(7)的位置与所述接地电极(5)的位置为一一对应；
    在每个所述固定电极组件的两侧分别形成贯通所述牺牲层(18)和所述第二介质层(10)的第一通孔(20)；
    在所述第二介质层(10)上覆盖振膜(3)，并封堵住所述第一通孔(20)，所述可动电极(7)与所述振膜(3)固定连接，并在所述振膜(3)及所述第二介质层(10)上形成第二通孔(21)；
    去除相邻的两个所述第一通孔(20)之间的所述牺牲层(18)形成空腔(24)，至少将所述固定电极组件及支撑柱(8)封装在空腔(24)内，所述第二通孔(21)与所述空腔(24)连通；
    封堵住所述第二通孔(21)，并使所述空腔(24)具有设定真空度以形成真空腔(4)；
    在所述衬底(1)的边缘设置导电通孔(22)，所述导电通孔(22)贯穿所述牺牲层(18)、所述第二介质层(10)及所述振膜(3)，并使所述 导电通孔(22)的一端与所述高偏压电极(6)电连接；
    在所述导电通孔(22)的另一端设置电连接部(23)，将所述电连接部(23)布设于所述振膜(3)的表面。
  12. 根据权利要求11所述的传感器芯片的制作方法，其特征在于，在所述振膜(3)与所述可动电极(7)固定连接的步骤中，包括：
    将所述所述可动电极(7)连接在所述振膜(3)位于所述真空腔(4)的一侧，以使所述可动电极(7)位于所述真空腔(4)之内；或者，
    将所述可动电极(7)嵌设于所述振膜(3)内，使所述可动电极(7)位于所述真空腔(4)之外。
  13. 一种电容传感器，其特征在于，包括：
    封装结构；及
    如权利要求1-10中任一项所述的传感器芯片，所述传感器芯片设置于所述封装结构内。
  14. 根据权利要求13所述的电容传感器，其特征在于，所述封装结构包括电路板(11)及设置于所述电路板(11)一侧的封装层(12)，所述传感器芯片设于所述电路板(11)，且所述封装层(12)围设在所述传感器芯片的外周侧。
  15. 根据权利要求13所述的电容传感器，其特征在于，在所述传感器芯片上覆盖有临时保护层(13)。
  16. 根据权利要求13所述的电容传感器，其特征在于，所述封装结构包括电路板(11)及设置于所述电路板(11)一侧的外壳(14)，所述电路板(11)与所述外壳(14)围合形成容置腔(15)；
    所述传感器芯片位于所述容置腔(15)之内，并固定设置在所述电路板(11)上，在所述电路板(11)上还设置有ASIC芯片(16)；
    所述外壳(14)或者所述电路板(11)上开设有与外部连通的声孔(17)。
  17. 一种电子设备，其特征在于，包括如权利要求13-16中任一项所述的电容传感器。
PCT/CN2023/133014 2022-11-21 2023-11-21 传感器芯片及其制作方法、电容传感器和电子设备 WO2024109749A1 (zh)

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