Wafer level packaged electric field sensor, electric field detection method, preparation method and sensor

Abstract

The present disclosure provides a wafer level packaged electric field sensor, an electric field detection method, a preparation method and a sensor, and is applied to the technical field of electric field sensors. The wafer level packaged electric field sensor comprises: a substrate for supporting a sensitive structure and a wafer level packaged cover plate; the sensitive structure is fixed above the substrate through an anchor point, the sensitive structure comprises an electric field sensing electrode unit and a displacement reference electrode unit, and is used for generating an induced electric signal by the electric field sensing electrode unit and a displacement reference electric signal by the displacement reference electrode unit in the case of applying an excitation to the sensitive structure, so as to compensate for a common mode error of the wafer level packaged electric field sensor according to the induced electric signal and the displacement reference electric signal, and improve the output sensitivity of the wafer level packaged electric field sensor; the wafer level packaged cover plate is arranged above the sensitive structure and is used for forming a sealed chamber together with the substrate, so that the sensitive structure in the sealed chamber is in a vacuum working environment, and the quality factor of the sensor is improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of electric field sensor, and more particularly to a wafer-level packaged electric field sensor, an electric field detection method, a preparation method and the sensor. BACKGROUND

[0002] Due to the advantages of small size, light weight and low cost, the electric field sensor based on micro-electro-mechanical system (MEMS) is widely used in many fields, such as aerospace, meteorology, power, industrial production, etc. However, the existing MEMS electric field sensor based on charge induction principle is affected by the temperature and other external environment, resulting in low output sensitivity and resolution, which cannot meet the high requirements of the existing electric field sensor.

[0003] In the process of realizing the above-mentioned inventive concept, the inventors found that in the related art, due to the influence of the common mode of the existing electric field sensor on the temperature and other external environment, the output sensitivity and output resolution of the electric field sensor are poor, which reduces the accuracy and stability of the electric field sensor in measuring electric field, and the high-damping working environment in which the driving structure is located and the crosstalk noise introduced in the process of applying excitation voltage to the driving structure also further reduce the output sensitivity and output resolution of the electric field sensor. SUMMARY

[0004] In view of the above problems, the present disclosure provides a wafer-level packaged electric field sensor, an electric field detection method, a preparation method and the sensor.

[0005] According to a first aspect of the present disclosure, a wafer-level packaged electric field sensor is provided, comprising: a substrate for supporting a sensitive structure and a wafer-level packaged cover plate, the surface of the substrate being provided with an anchor point; the sensitive structure is fixed above the substrate through the anchor point, the sensitive structure comprising an electric field sensing electrode unit and a displacement reference electrode unit, for generating an induced electric signal by the electric field sensing electrode unit and a displacement reference electric signal by the displacement reference electrode unit under the condition of applying excitation to the sensitive structure, so as to compensate for the common mode error of the wafer-level packaged electric field sensor according to the induced electric signal and the displacement reference electric signal, and improve the output sensitivity of the wafer-level packaged electric field sensor; the wafer-level packaged cover plate is arranged above the sensitive structure, and is used to form a sealed chamber together with the substrate, so that the sensitive structure in the sealed chamber is in a vacuum working environment, so as to improve the quality factor of the wafer-level packaged electric field sensor.

[0006] According to an embodiment of the present disclosure, the sensitive structure further comprises a driving structure unit and a movable structure unit; the driving structure unit is arranged on one side of the movable structure unit and is used to drive the movable structure unit to generate vibration; the movable structure unit is arranged above the center of the substrate and is used to generate vibration in response to the driving structure unit, so that the electric field sensing electrode unit and the displacement reference electrode unit generate an induced electric signal and a displacement reference electric signal, respectively.

[0007] According to an embodiment of the present disclosure, the movable structure unit comprises a first comb structure and a second comb structure, the electric field sensing electrode unit generates an induced electric signal, and the displacement reference electrode unit generates a displacement reference electric signal, and the method comprises: the first comb structure is arranged on one side of the electric field sensing electrode unit and is differentially staggered with the comb structure of the electric field sensing electrode unit, and is used to generate and output an induced electric signal based on the principle of charge induction in response to vibration of the first comb structure; the second comb structure is arranged on one side of the displacement reference electrode unit and is staggered with the comb structure of the displacement reference electrode unit, and is used to change the capacitance between the second comb structure and the comb structure of the displacement reference electrode unit in response to vibration of the second comb structure, and generate and output a displacement reference electric signal according to the capacitance change.

[0008] According to an embodiment of the present disclosure, the wafer-level packaging cover plate comprises a cover plate, an insulating medium layer, and an electric field enhancement structure; the lower surface of the cover plate is fixed above the substrate through the insulating medium layer, and is used to form a sealed cavity with the insulating medium layer and the substrate; the electric field enhancement structure is arranged on the upper surface of the cover plate or the lower surface of the cover plate, and is located directly above the sensitive structure, and is used to concentrate the electric field to be measured, so as to enhance the electric field strength acting on the sensitive structure.

[0009] According to an embodiment of the present disclosure, the movable structure unit further comprises an elastic beam, the elastic beam is arranged on both sides of the first comb structure and the second comb structure, and is used to support the first comb structure and the second comb structure; the elastic beam is one of a straight beam, a folded beam, and a curved beam, or a combination thereof.

[0010] According to an embodiment of the present disclosure, the resonator comprises an elastic beam and the first comb structure and / or the second comb structure, the movable structure unit is a single resonator structure or a multi-resonator coupling structure; the single resonator structure comprises one resonator and is used to vibrate the first comb structure and the second comb structure with the same amplitude in response to the driving of the driving structure unit, so as to make the output sensitivity of the wafer-level packaging electric field sensor a predetermined value; the multi-resonator coupling structure comprises a plurality of resonators and is used to vibrate the first comb structure and the second comb structure with different amplitudes in response to the driving of the driving structure unit, so as to improve the output sensitivity of the wafer-level packaging electric field sensor.

[0011] The second aspect of the present disclosure provides an electric field detection method, comprising: placing a wafer-level packaged electric field sensor in an electric field to be detected; applying an excitation to a driving structure unit of the wafer-level packaged electric field sensor to make a movable structure unit vibrate; in response to vibration of a second comb structure in the movable structure unit, a displacement reference electrode unit generates and outputs a displacement reference electrical signal according to a change in capacitance between the second comb structure and a comb structure of the displacement reference electrode unit; inputting the displacement reference electrical signal to a closed-loop feedback circuit; based on the displacement reference electrical signal, the closed-loop feedback circuit adjusts the voltage size of the excitation to obtain a wafer-level packaged electric field sensor with constant sensitivity; in response to vibration of a first comb structure of the wafer-level packaged electric field sensor with constant sensitivity, based on the principle of charge induction, an electric field sensing electrode unit generates and outputs an induced electrical signal; comparing and outputting the induced electrical signal and the displacement reference electrical signal to obtain the electric field strength of the electric field to be detected.

[0012] The third aspect of the present disclosure provides a preparation method of a wafer-level packaged electric field sensor, comprising: etching a groove on a silicon-on-insulator device layer by using a photolithography etching process to obtain a cover plate containing the groove; depositing a getter on the inner surface of the groove by using an evaporation process to obtain a wafer-level packaged cover plate; etching on a silicon-on-insulator device layer by using a photolithography etching process to obtain a substrate connected with a sensitive structure, wherein the silicon-on-insulator is the substrate; etching the silicon oxide layer in the substrate connected with the sensitive structure by using a wet etching process to release the electric field sensitive structure in the substrate to facilitate free vibration of the electric field sensitive structure; after aligning the wafer-level packaged cover plate and the substrate, performing an anodic bonding or silicon-silicon bonding operation to obtain a wafer-level packaged electric field sensor.

[0013] The fourth aspect of the present disclosure provides an electric field sensor, comprising: a wafer-level packaged electric field sensor with the above structure or a wafer-level packaged electric field sensor obtained by the above preparation method.

[0014] According to the embodiments of the present disclosure, the electric field sensor further comprises a two-dimensional or three-dimensional electric field sensor composed of a plurality of electric field sensitive structures, for measuring a two-dimensional or three-dimensional electric field or voltage.

[0015] According to the wafer-level packaged electric field sensor, the electric field detection method, the preparation method and the sensor of the present disclosure, the wafer-level packaged electric field sensor comprises a substrate, a sensitive structure and a wafer-level packaged cover plate, the sensitive structure is fixed on the substrate through an anchor point, the wafer-level packaged cover plate is arranged above the sensitive structure, and the sensitive structure comprises an electric field sensing electrode unit and a displacement reference electrode unit. In the case of applying an excitation to the sensitive structure, the electric field sensing electrode unit generates an induced electric signal, and the displacement reference electrode unit generates a displacement reference electric signal. The wafer-level packaged electric field sensor can obtain an accurate measurement result corresponding to the to-be-measured electric field according to the result of comparison between the induced electric signal and the displacement reference electric signal, the measurement efficiency is improved, and in the case of generating the induced electric signal by the electric field sensing electrode unit and generating the displacement reference electric signal by the displacement reference electrode unit, the induced electric signal and the displacement reference electric signal can be output in a differential form. The common-mode error caused by the external environment such as temperature is eliminated through the differential signals output by the electric field sensing electrode unit and the displacement reference electrode unit, the output sensitivity and resolution are avoided to be reduced by different measurement environments, the stability of the device parameters such as the output sensitivity and resolution of the wafer-level electric field sensor is maintained, and the stability of the wafer-level packaged electric field sensor is improved.

[0016] According to the embodiments of the present disclosure, further, the wafer-level packaged cover plate is arranged above the sensitive structure, so that a sealed cavity is formed between the wafer-level packaged cover plate and the substrate, the sensitive structure is located in the sealed cavity, and the sealed cavity is in a vacuum environment, so that the sensitive structure works in the working environment of the vacuum environment, that is, the wafer-level electric field sensor is vacuum packaged, so that the damping of the wafer-level electric field sensor is reduced, the quality factor of the wafer-level electric field sensor is improved, the crosstalk noise caused by the excitation applied to the electric field sensing electrode unit is reduced, and since the quality factor and the resonance amplitude are in a proportional relationship, the quality factor is improved, and the amplitude of the sensitive structure is also improved, so that the wafer-level electric field sensor outputs a larger electric signal under the driving of the same excitation, and the sensitivity is higher.

[0017] According to the embodiments of the present disclosure, further, the wafer-level electric field sensor of the present disclosure can be applied to the measurement environment of electric fields in various fields, and accurate measurement can be achieved for electric fields in various environments. The wafer-level packaging process can also improve the manufacturing efficiency of batch manufacturing of the sensor, and has high application value. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of the embodiments of the present disclosure taken in conjunction with the accompanying drawings, in which:

[0019] Figure 1A structural schematic diagram of a wafer-level packaged electric field sensor is shown schematically according to an embodiment of the present disclosure;

[0020] Figure 2 A sensitive structure of a wafer-level packaged electric field sensor is shown schematically according to an embodiment of the present disclosure;

[0021] Figure 3 A movable structure of a wafer-level packaged electric field sensor is shown schematically according to an embodiment of the present disclosure;

[0022] Figure 4 A sensitive structure of a wafer-level packaged electric field sensor with a movable structure as a multi-resonator array is shown schematically according to an embodiment of the present disclosure;

[0023] Figure 5 A wafer-level packaged cover plate of a wafer-level packaged electric field sensor is shown schematically according to an embodiment of the present disclosure;

[0024] Figure 6 A flowchart of an electric field detection method is shown schematically according to an embodiment of the present disclosure;

[0025] Figure 7 A flowchart of a preparation method of a wafer-level packaged electric field sensor is shown schematically according to an embodiment of the present disclosure;

[0026] Figure 8 A preparation method of a wafer-level packaged electric field sensor is shown schematically according to an embodiment of the present disclosure;

[0027] Figure 9 A preparation method of a wafer-level packaged electric field sensor is shown schematically according to another embodiment of the present disclosure.

[0028] Reference signs:

[0029] Substrate 110, sensitive structure 120, wafer-level packaged cover plate 130, anchor point 111, movable structure unit 210, driving structure unit 220, electric field sensing electrode unit 230, displacement reference electrode unit 240, elastic beam 310, first comb-tooth structure 320, second comb-tooth structure 330, coupling structure 410, cover plate 510, insulating dielectric layer 520, and electric field enhancement structure 530. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It is to be understood, however, that the description is merely exemplary and is intended to provide a thorough understanding of the present disclosure. In the following detailed description of embodiments of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it would be apparent to those skilled in the art that the present disclosure can be practiced without these specific details. In other instances, well-known structures and functions have not been described in detail in order to avoid obscuring the concepts of the present disclosure.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the term "includes" and tautological expressions thereof, such as "including," "includes," "include," "contains," "containing," and so forth, shall be read expansively and without limitation. The terms "comprising," "comprise" and / or "comprised of," and tautological expressions thereof (e.g., "comprising of") will be understood to enable recitations that they do not exclude additional matter.

[0032] All terms used herein including technical and scientific terms have the same meanings as commonly understood by one of ordinary skill in the art unless otherwise defined herein. It should be noted that the terms used herein are merely specific ones and are not intended to limit the present disclosure. Rather, the terms are to be interpreted to have meanings that are consistent with the context of the present description, and should not be interpreted in an idealized or overly formal manner.

[0033] In the case of using expressions similar to "at least one of A, B, and C, etc.", it should generally be interpreted to include any of them, to include, for example, a system having at least one of A, B, or C, to include a system having A alone, to include a system having B alone, to include a system having C alone, to include a system having 2 of A, B, and C, to include a system having 3 of A, B, and C, and the like.

[0034] In the technical solutions of the present disclosure, the user information (including but not limited to user personal information, user image information, user equipment information, such as location information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved are all information and data authorized by the user or authorized by all parties, and the collection, storage, use, processing, transmission, provision, disclosure and application of related data comply with relevant laws, regulations and standards, take necessary security measures, do not violate public order and good customs, and provide corresponding operation portal for user to choose authorization or refusal.

[0035] The electric field sensor based on the micro-electro-mechanical system (MEMS) has the advantages of small size, light weight and low cost, and is widely used in many fields, such as aerospace, meteorology, power, industrial production, etc. The existing MEMS electric field sensor is mainly designed based on the charge induction principle. However, when measuring the electric field by using the existing electric field sensor, due to the low sensitivity of the electric field sensor, an accurate electric field detection result cannot be obtained.

[0036] Further, researchers carry out further research on the electric field sensor designed based on the principle of charge induction in order to meet the high demand for electric field sensors. In the process of research and development, researchers find that in the related art, due to the influence of the common mode of the existing electric field sensor on the external environment such as temperature, the output sensitivity and output resolution of the electric field sensor are poor, which reduces the accuracy and stability of the electric field sensor in measuring the electric field, and the high damping working environment in which the driving structure is located and the crosstalk noise introduced in the process of applying an excitation voltage to the driving structure further reduce the output sensitivity and output resolution of the electric field sensor.

[0037] Therefore, embodiments of the present disclosure provide a wafer-level packaged electric field sensor, which comprises a substrate, a sensitive structure and a wafer-level packaged cover plate. The surface of the substrate is provided with anchor points. The sensitive structure is fixed above the substrate through the anchor points. The sensitive structure comprises an electric field induction electrode unit and a displacement reference electrode unit. In the case of applying an excitation to the sensitive structure, the electric field induction electrode unit generates an induced electric signal, and the displacement reference electrode unit generates a displacement reference electric signal. The common mode error of the wafer-level packaged electric field sensor is compensated according to the induced electric signal and the displacement reference electric signal, and the output sensitivity of the wafer-level packaged electric field sensor is improved. The wafer-level packaged cover plate is arranged above the sensitive structure and is used to form a sealed chamber together with the substrate, so that the sensitive structure in the sealed chamber is in a vacuum working environment, thereby improving the quality factor of the wafer-level packaged electric field sensor.

[0038] The following will be described in detail Figures 1-5 The wafer-level packaged electric field sensor of the disclosed embodiments will be described in detail.

[0039] According to embodiments of the present disclosure, the wafer-level packaged electric field sensor can comprise a substrate, a sensitive structure and a wafer-level packaged cover plate.

[0040] According to embodiments of the present disclosure, the substrate can be used to support the sensitive structure and the wafer-level packaged cover plate. The surface of the substrate can be provided with a plurality of anchor points.

[0041] According to embodiments of the present disclosure, the sensitive structure is fixed above the substrate through the anchor points. The sensitive structure comprises an electric field induction electrode unit and a displacement reference electrode unit. In the case of applying an excitation to the sensitive structure, the electric field induction electrode unit generates an induced electric signal, and the displacement reference electrode unit generates a displacement reference electric signal. The common mode error of the wafer-level packaged electric field sensor is compensated according to the induced electric signal and the displacement reference electric signal, and the output sensitivity of the wafer-level packaged electric field sensor is improved.

[0042] According to an embodiment of the present disclosure, the induced electric signal can be an induced electric current signal, and the displacement reference electric signal can be a displacement reference electric current signal.

[0043] According to an embodiment of the present disclosure, the wafer-level packaged electric field sensor can include at least one electric field sensing electrode unit and at least one displacement reference electrode unit. In the case that an excitation is applied to the sensitive structure, the induced electric current signals generated by the plurality of electric field sensing electrode units can be output in a differential form, and the displacement reference electric current signals generated by the plurality of displacement reference electrode units can also be output in a differential form. According to the output differential signals, common-mode errors can be eliminated.

[0044] According to an embodiment of the present disclosure, the wafer-level packaged cover plate is arranged above the sensitive structure, and can be used to form a sealed chamber together with the substrate, so that the sensitive structure in the sealed chamber is in a vacuum working environment, thereby improving the quality factor of the wafer-level packaged electric field sensor.

[0045] According to an embodiment of the present disclosure, the wafer-level packaged electric field sensor includes a substrate, a sensitive structure, and a wafer-level packaged cover plate. The sensitive structure is fixed to the substrate through an anchor point, and the wafer-level packaged cover plate is arranged above the sensitive structure. The sensitive structure includes an electric field sensing electrode unit and a displacement reference electrode unit. In the case that an excitation is applied to the sensitive structure, the electric field sensing electrode unit generates an induced electric signal, and the displacement reference electrode unit generates a displacement reference electric signal. In the case that the electric field to be measured is detected, the accurate measurement result corresponding to the electric field to be measured can be obtained according to the comparison result between the induced electric signal and the displacement reference electric signal, thereby improving the measurement efficiency. In addition, the induced electric signal and the displacement reference electric signal can be output in a differential form at the same time when the electric field sensing electrode unit generates the induced electric signal and the displacement reference electrode unit generates the displacement reference electric signal. The differential signals output by the electric field sensing electrode unit and the displacement reference electrode unit eliminate common-mode errors caused by external environments such as temperature, avoid different measurement environments to reduce the output sensitivity and resolution, maintain the stability of the device parameters of the wafer-level packaged electric field sensor such as the output sensitivity and resolution of the wafer-level packaged electric field sensor, and improve the stability of the wafer-level packaged electric field sensor.

[0046] According to the embodiment of the present disclosure, further, by arranging the wafer-level packaging cover plate above the sensitive structure, so that a closed chamber is formed between the wafer-level packaging cover plate and the substrate, the sensitive structure is located in the closed chamber, and the closed chamber is in a vacuum environment, so that the sensitive structure works in the working environment of the vacuum environment, that is, the wafer-level electric field sensor is vacuum packaged, thereby reducing the damping of the wafer-level electric field sensor, improving the quality factor of the wafer-level electric field sensor, reducing the crosstalk noise generated due to the excitation applied on the electric field sensing electrode unit, and since the quality factor and the resonance amplitude are in a proportional relationship, the quality factor is improved, and the amplitude of the sensitive structure is also improved, so that the wafer-level electric field sensor outputs a larger electric signal under the same excitation driving, and the sensitivity is higher.

[0047] According to the embodiment of the present disclosure, further, the wafer-level electric field sensor of the present disclosure can be applied to various fields of electric field measurement environment, and can accurately measure the electric field of various environments, and the wafer-level packaging process can also improve the manufacturing efficiency of batch manufacturing of the sensor, and has high application value.

[0048] Figure 1 A schematic diagram of the structure of the wafer-level packaged electric field sensor according to the embodiment of the present disclosure is shown.

[0049] As shown in Figure 1 , Figure 1 The structure of the wafer-level packaged electric field sensor is shown, which includes a substrate 110, a sensitive structure 120, and a wafer-level packaging cover plate 130. The substrate is provided with a plurality of anchor points 111, the sensitive structure 120 is arranged on the substrate 110 through the plurality of anchor points 111, and the wafer-level packaging cover plate 130 is arranged on the substrate 110 and forms a closed chamber with the substrate 110, so that the sensitive structure 120 is in the closed chamber and can work in a vacuum environment, thereby improving the quality factor and output sensitivity of the wafer-level packaged electric field sensor.

[0050] According to the embodiment of the present disclosure, the sensitive structure further includes a driving structure unit and a movable structure unit.

[0051] According to the embodiment of the present disclosure, the driving structure unit can be arranged on one side of the movable structure unit, and is used to drive the movable structure unit to vibrate.

[0052] According to an embodiment of the present disclosure, the drive structure unit can also be arranged on both sides of the movable structure unit. For example, in the case of a wafer-level packaged electric field sensor containing one movable structure unit, there can be two drive structure units, and the two drive structure units can be respectively located on both sides of the movable structure unit. In the case of a wafer-level packaged electric field sensor containing two movable structure units, there can be two drive structure units, and the first drive structure unit can be located on the outside (left side) of the first movable structure unit, and the second drive structure unit can be located on the outside (right side) of the second movable structure unit.

[0053] According to an embodiment of the present disclosure, the drive mode of the drive structure unit includes at least one of the following: electrostatic comb drive, electrostatic flat plate drive, piezoelectric drive, magnetic drive, and thermal drive.

[0054] According to an embodiment of the present disclosure, the movable structure unit is arranged above the center of the substrate, and is used to generate vibration in response to the drive structure unit, so that the electric field sensing electrode unit and the displacement reference electrode unit respectively generate an induced electric signal and a displacement reference electric signal.

[0055] According to an embodiment of the present disclosure, the sensitive structure can include at least one drive structure unit and at least one movable structure unit. In the case of containing multiple movable structure units, the multiple movable structure units can be connected through at least one coupling structure. For example, in the case of a wafer-level packaged electric field sensor containing two movable structure units, there can be two drive structure units, and two coupling structures. The first drive structure unit can be located on the outside (left side) of the first movable structure unit, and the second drive structure unit can be located on the outside (right side) of the second movable structure unit. The first coupling structure can be located above the position between the first movable structure unit and the second movable structure unit, and the first coupling structure can be located below the position between the first movable structure unit and the second movable structure unit.

[0056] According to an embodiment of the present disclosure, the sensitive structure can also include a drive structure unit and a movable structure unit. The drive structure unit can be arranged on one side or both sides of the movable structure unit, and the movable structure unit can be arranged above the center of the substrate. By applying an excitation voltage to the drive structure unit, the movable structure unit generates vibration, the electric field sensing electrode unit arranged opposite to the movable structure unit generates an induced electric signal, and the displacement reference electrode unit generates a displacement reference electric signal. In this way, the vibration of the movable structure unit is realized, and the electrode unit outputs an electric signal for detecting or eliminating the modulus error.

[0057] Figure 2 The schematic diagram of the sensitive structure of the wafer-level packaged electric field sensor according to an embodiment of the present disclosure is schematically shown.

[0058] AsFigure 2 As shown, Figure 2 The sensing structure of a wafer-level packaged electric field sensor is shown. The sensing structure includes a movable structural unit 210, a driving structural unit 220, an electric field sensing electrode unit 230, and a displacement reference electrode unit 240. Figure 2 It includes one movable structural unit 210, four driving structural units 220, two electric field sensing electrode units 230, and four displacement reference electrode units 240. The comb teeth of the four driving structural units 220 are arranged alternately with the comb teeth of the movable structural unit 210. The first and second driving structural units 220 are located to the left of the movable structural unit 210. The first driving structural unit 220 is positioned opposite to the upper comb teeth of the movable structural unit 210, and the second driving structural unit 220 is positioned opposite to the lower comb teeth of the movable structural unit 210. The third driving structural unit 220... The third drive structure unit 220 is positioned to the right of the movable structure unit 210. The third drive structure unit 220 is positioned opposite to the upper comb structure of the movable structure unit 210. The fourth drive structure unit 220 is positioned opposite to the lower comb structure of the movable structure unit 210. The comb teeth of the four displacement reference electrode units 240 are arranged alternately with the comb teeth of the movable structure unit 210. The first displacement reference electrode unit 240 and the second displacement reference electrode unit 240 are positioned to the left of the movable structure unit 210 and to the right of the first drive structure unit 220 and the second drive structure unit 220. The first displacement reference electrode unit 240 is positioned opposite to the upper comb tooth structure of the movable structure unit 210. The second displacement reference electrode unit 240 is positioned opposite to the lower comb tooth structure of the movable structure unit 210. The third and fourth displacement reference electrode units 240 are positioned to the right of the movable structure unit 210 and to the left of the third and fourth drive structure units 220. The third displacement reference electrode unit 240 is positioned opposite to the upper comb tooth structure of the movable structure unit 210, and the fourth displacement reference electrode unit 240 is positioned opposite to the lower comb tooth structure of the movable structure unit 210. In this configuration, the comb teeth of the two electric field sensing electrode units 230 and the comb tooth structure of the movable structure unit 210 are arranged in a differentially staggered manner. The first electric field sensing electrode unit 230 is disposed between the first displacement reference electrode unit 240 and the third displacement reference electrode unit 240, and the second electric field sensing electrode unit 230 is disposed between the second displacement reference electrode unit 240 and the fourth displacement reference electrode unit 240. The first electric field sensing electrode unit 230 is disposed opposite to the upper comb tooth structure of the movable structure unit 210, and the second electric field sensing electrode unit 230 is disposed opposite to the lower comb tooth structure of the movable structure unit 210.

[0059] According to an embodiment of the present disclosure, in the case that an excitation is applied to the driving structure unit 220, the movable structure unit 210 generates vibration in response to the driving structure unit 220, so as to make the comb structure arranged in a differential interleaved manner with the electric field sensing electrode unit 230 and the displacement reference electrode unit 240 vibrate, and the electric field sensing electrode unit 230 outputs an induced electric signal based on the electric charge induction principle and the amount of capacitance change, and the displacement reference electrode unit 240 outputs a displacement reference electric signal.

[0060] According to an embodiment of the present disclosure, the movable structure unit comprises a first comb structure, a second comb structure and an elastic beam.

[0061] According to an embodiment of the present disclosure, the first comb structure is arranged on one side of the electric field sensing electrode unit and arranged in a differential interleaved manner with the comb structure of the electric field sensing electrode unit, and used for generating and outputting an induced electric signal by the electric field sensing electrode unit based on the electric charge induction principle in response to the vibration of the first comb structure.

[0062] According to an embodiment of the present disclosure, the comb structure can increase the sensing area, so as to enhance the output induced electric signal, and further, the output induced electric signal can also be enhanced by arranging the electrode comb of the electric field sensing electrode unit in a differential interleaved manner with the comb structure.

[0063] According to an embodiment of the present disclosure, the second comb structure is arranged on one side of the displacement reference electrode unit and arranged in an interleaved manner with the comb structure of the displacement reference electrode unit, and used for changing the capacitance between the second comb structure and the comb structure of the displacement reference electrode unit in response to the vibration of the second comb structure, and generating and outputting a displacement reference electric signal by the displacement reference electrode unit according to the amount of capacitance change.

[0064] According to an embodiment of the present disclosure, the elastic beam is arranged on both sides of the first comb structure and the second comb structure, and used for supporting the first comb structure and the second comb structure.

[0065] According to an embodiment of the present disclosure, the elastic beam is one or a combination of a straight beam, a folded beam and a curved beam.

[0066] According to an embodiment of the present disclosure, the driving structure unit, the movable structure unit, the electric field sensing electrode unit and the displacement reference electrode unit can be fixed on the substrate through an anchor point.

[0067] According to an embodiment of the present disclosure, the movable structure unit can include at least one elastic beam, at least one first comb structure, and at least one second comb structure. For example, two elastic beams, two first comb structures, and four second comb structures can be included in the movable structure, the two first comb structures are arranged above the center of the substrate, the first second comb structure can be located on the left side of the first comb structure, the second second comb structure can be located on the right side of the first comb structure, the first elastic beam is arranged on the left side of the first second comb structure, and the second elastic beam is arranged on the right side of the second second comb structure. The two elastic beams, the two first comb structures, and the two second comb structures included in the movable structure are all located on the substrate.

[0068] According to an embodiment of the present disclosure, the movable structure unit can include a first comb structure, a second comb structure, and an elastic beam, the elastic beam can be arranged on both sides of the first comb structure and the second comb structure, the elastic beam can support the first comb structure and the second comb structure, and at the same time, the elastic beam can also allow the first comb structure and the second comb structure to have a certain space for vibration with a predetermined amplitude when the first comb structure and the second comb structure vibrate. The first comb structure and the second comb structure in the movable structure unit are differentially staggered with the comb structure of the electric field sensing electrode unit and the comb structure of the displacement reference electrode unit. By applying an excitation to the driving structure unit, the first comb structure and the second comb structure in the movable structure unit are driven to vibrate, thereby realizing driving and detection. Based on the charge induction principle, the electric field sensing electrode unit on one side of the first comb structure outputs an induced electric signal, and based on the capacitance change between the second comb structure and the comb structure of the displacement reference electrode unit, the displacement reference electrode unit outputs a displacement reference electric signal. In the case where the first comb structure and the second comb structure in the movable structure unit vibrate, the electric field sensing electrode unit and the displacement reference electrode unit respectively output the induced electric signal and the displacement reference electric signal. Further, by the comb structure and the staggered arrangement, the output induced electric signal can be further enhanced, and the capacitance change can be improved, and the output displacement reference electric signal can be enhanced, so as to eliminate the common mode error and measure the electric field.

[0069] Figure 3 A schematic diagram of a movable structure of a wafer-level packaged electric field sensor is schematically shown according to an embodiment of the present disclosure.

[0070] As Figure 3 shown, Figure 3 A movable structure of a wafer-level packaged electric field sensor is shown, the movable structure includes an elastic beam 310, a first comb structure 320, and a second comb structure 330, as shown in the figure, Figure 3The movable structure shown includes two elastic beams 310, two first comb structures 320 and four second comb structures 330, the elastic beams 310, the first comb structures 320 and the second comb structures 330 are all located above the substrate, the first elastic beam 310 is arranged on the left side of the first second comb structure 330, the second elastic beam 310 is arranged on the right side of the fourth second comb structure 330, the first first comb structure 320 is arranged above the second second comb structure 330 and the third second comb structure 330, connected with the second comb structure 330, the second first comb structure 320 is arranged below the second second comb structure 330 and the third second comb structure 330, connected with the first first comb structure 320, by connecting the elastic beams 310, the first comb structures 320 and the second comb structures 330, the first comb structures 320 and the second comb structures 330 in the movable structure unit will all vibrate under the excitation of the driving structure unit, so as to make the electric field sensing electrode unit and the displacement reference electrode unit generate sensing electric signals and displacement reference electric signals respectively.

[0071] According to embodiments of the present disclosure, the resonator includes an elastic beam and a first comb structure and / or a second comb structure, and the movable structure unit can be a single resonator structure or a multi-resonator coupling structure.

[0072] According to embodiments of the present disclosure, the single resonator structure includes one resonator, and the first comb structure and the second comb structure vibrate with the same amplitude in response to the driving of the driving structure unit, so as to facilitate the output sensitivity of the wafer-level packaged electric field sensor to be a predetermined value.

[0073] According to embodiments of the present disclosure, the resonator included in the single resonator structure can be composed of an elastic beam, a first comb structure and a second comb structure.

[0074] According to embodiments of the present disclosure, the multi-resonator coupling structure includes a plurality of resonators, and the first comb structure and the second comb structure vibrate with different amplitudes in response to the driving of the driving structure unit, so as to facilitate the output sensitivity of the wafer-level packaged electric field sensor to be improved.

[0075] According to an embodiment of the present disclosure, the plurality of resonators included in the multi-resonator coupling structure can be composed of an elastic beam and a first comb structure, and can also be composed of an elastic beam and a second comb structure. In the multi-resonator coupling structure, the plurality of resonators can be coupled through at least one coupling structure, and in response to driving of the drive structure unit, the plurality of resonators can vibrate with different amplitudes based on the principle of modal localization, so that the output sensitivity of the sensor can be adjusted. For example, in the case of a movable structure unit of a wafer-level packaged electric field sensor being a multi-resonator coupling structure, the movable structure unit can include two resonators connected by two coupling structures, the first resonator is composed of an elastic beam and a first comb structure, and the second resonator is composed of an elastic beam and a second comb structure, the upper ends of the first resonator and the second resonator are linked by the first coupling structure, and the lower ends of the first resonator and the second resonator are linked by the second coupling structure.

[0076] According to an embodiment of the present disclosure, the coupling structure includes one of the following: an electrostatic coupling structure, a mechanical coupling structure, and a mechanical-electrostatic hybrid coupling structure.

[0077] According to an embodiment of the present disclosure, the resonator can include an elastic beam and a first comb structure and / or a second comb structure, and the movable structure unit in the sensor can be a single-resonator structure or a multi-resonator coupling structure. In the case of the movable structure unit being a single-resonator structure, in response to driving of the drive structure unit, the first comb structure and the second comb structure can vibrate with the same amplitude, so that the output sensitivity of the wafer-level packaged electric field sensor is a predetermined value, thereby improving the stability of the output sensitivity. In the case of the movable structure unit being a multi-resonator coupling structure, in response to driving of the drive structure unit, based on the principle of modal localization, the first comb structure and the second comb structure can vibrate with different amplitudes, so that the output sensitivity of the wafer-level packaged electric field sensor can be adjusted, thereby improving the output sensitivity of the sensor.

[0078] Figure 4 A schematic diagram of a sensitive structure of a wafer-level packaged electric field sensor with a movable structure being a multi-resonator array according to an embodiment of the present disclosure is schematically shown.

[0079] As Figure 4 shown, Figure 4The movable structure in the sensitive structure is a structure of a multi-resonator array, the sensitive structure includes two driving structure units 220, two electric field sensing electrode units 230, two displacement reference electrode units 240, and one movable structure unit composed of two resonator arrays, the first resonator includes two elastic beams 310 and two second comb tooth structures 330, the second resonator includes two elastic beams 310 and two first comb tooth structures 320, and the two resonators are connected through two coupling structures 410. The comb tooth structures of the first electric field sensing electrode unit 230 are staggered with the first second comb tooth structure 330 in the first resonator, the comb tooth structures of the second electric field sensing electrode unit 230 are staggered with the second second comb tooth structure 330 in the first resonator, the first elastic beam 310 in the first resonator is located on the left side of the second comb tooth structure 330, the second elastic beam 310 in the first resonator is located on the right side of the second comb tooth structure 330, and the first driving structure unit 220 is located on the left side of the first elastic beam 310 in the first resonator. The comb tooth structures of the first displacement reference electrode unit 240 are differentially staggered with the first first comb tooth structure 320 in the second resonator, the comb tooth structures of the second displacement reference electrode unit 240 are differentially staggered with the second first comb tooth structure 320 in the second resonator, the first elastic beam 310 in the second resonator is located on the left side of the first comb tooth structure 320, the second elastic beam 310 in the second resonator is located on the right side of the first comb tooth structure 320, and the second driving structure unit 220 is located on the left side of the second elastic beam 310 in the second resonator. The first coupling structure 410 and the second coupling structure 410 are located between the first resonator and the second resonator.

[0080] According to an embodiment of the present disclosure, the wafer level package cover plate includes a cover plate, an insulating medium layer, and an electric field enhancement structure.

[0081] According to an embodiment of the present disclosure, the lower surface of the cover plate is fixed above the substrate through the insulating medium layer, for forming a sealed cavity with the insulating medium layer and the substrate, so that the sensitive structure can be in a vacuum working environment.

[0082] According to an embodiment of the present disclosure, the cover plate can be composed of one or more conductor materials, the insulating medium layer can be composed of one or more insulating materials, and can also be composed of a composite material with an outermost layer of insulating material.

[0083] According to the embodiment of the present disclosure, since the excitation is applied on the electric field sensing electrode unit, crosstalk noise can be generated, and therefore the wafer level electric field sensor is vacuum packaged so that the sensitive structure is located in a closed chamber, thereby reducing the damping of the wafer level electric field sensor, improving the quality factor of the wafer level electric field sensor, and reducing the influence of crosstalk noise. Further, since the quality factor and the resonance amplitude are in a proportional relationship, the amplitude of the sensitive structure can be increased while the quality factor is improved, so that the wafer level electric field sensor outputs a larger electrical signal and has higher sensitivity under the driving of the same size excitation.

[0084] According to the embodiment of the present disclosure, the electric field enhancement structure is arranged on the upper surface of the cover plate or the lower surface of the cover plate, and the electric field enhancement structure is located directly above the sensitive structure, and is used to concentrate the electric field to be measured, so as to enhance the electric field intensity acting on the sensitive structure.

[0085] According to the embodiment of the present disclosure, the structure shape of the electric field enhancement structure can include any one of the following: a rectangular parallelepiped, a cube, a circular truncated cone, a prism, a truncated prism, a circular cylinder, a circular cone, and an irregular body.

[0086] According to the embodiment of the present disclosure, the wafer level packaging cover plate includes a cover plate, an insulating medium layer, and an electric field enhancement structure. The lower surface of the cover plate is fixed above the substrate through the insulating medium layer, and is used to form a closed chamber with the insulating medium layer and the substrate. The electric field enhancement structure is arranged on the upper surface of the cover plate or the lower surface of the cover plate, and the electric field enhancement structure is located directly above the sensitive structure, and is used to concentrate the electric field to be measured, so as to enhance the electric field intensity acting on the sensitive structure. Therefore, while reducing the damping of the wafer level electric field sensor, improving the quality factor of the wafer level electric field sensor, and reducing the influence of crosstalk noise, the electric field intensity acting on the sensitive structure is enhanced, the amplitude of the sensitive structure is increased, the wafer level electric field sensor outputs a larger electrical signal and has higher sensitivity under the driving of the same size excitation, and the wafer level packaging process can also improve the manufacturing efficiency of batch manufacturing of the sensor and improve the application value.

[0087] Figure 5 A schematic diagram of a wafer level packaging cover plate of a wafer level packaging electric field sensor according to an embodiment of the present disclosure is shown schematically.

[0088] As shown in Figure 5 , Figure 5 A wafer level packaging cover plate of a wafer level packaging electric field sensor is shown, which includes a cover plate 510, an insulating medium layer 520, and an electric field enhancement structure 530. The lower surface of the cover plate 510 is connected with the insulating medium layer 520. The electric field enhancement structure 530 shown in the figure is located on the lower surface of the cover plate 510 and is arranged opposite to the sensitive structure, so as to form a closed chamber together with the substrate, so that the sensitive structure is in a vacuum working environment.

[0089] According to an embodiment of the present disclosure, the electric field sensor can include a wafer-level packaged electric field sensor of the structure as described above.

[0090] According to an embodiment of the present disclosure, the electric field sensor further includes a two-dimensional or three-dimensional electric field sensor composed of a plurality of electric field sensitive structures, which can be used to measure a two-dimensional or three-dimensional electric field or voltage.

[0091] Figure 6 A flowchart of an electric field detection method according to an embodiment of the present disclosure is schematically shown.

[0092] As shown in Figure 6 The electric field detection method of this embodiment includes operations S610-S670.

[0093] In operation S610, a wafer-level packaged electric field sensor is placed in an electric field to be measured.

[0094] In operation S620, an excitation is applied to a driving structure unit of the wafer-level packaged electric field sensor to make a movable structure unit vibrate.

[0095] According to an embodiment of the present disclosure, in the case where an excitation is applied to a driving structure unit of a wafer-level packaged electric field sensor, both the first comb structure and the second comb structure in the movable structure unit will vibrate. In the case where the movable structure unit is a single resonator structure, the first comb structure and the second comb structure in the movable structure unit can produce vibrations with consistent amplitudes, so that the output sensitivity of the sensor can be maintained. In the case where the movable structure unit is a multi-resonator coupling structure, the first comb structure and the second comb structure in the movable structure unit can produce vibrations with inconsistent amplitudes based on the principle of modal localization, so that the output sensitivity of the sensor can be improved.

[0096] In operation S630, in response to the vibration of the second comb structure in the movable structure unit, a displacement reference electrode unit generates and outputs a displacement reference electrical signal according to the amount of change in capacitance between the second comb structure and the comb structure of the displacement reference electrode unit.

[0097] According to an embodiment of the present disclosure, the displacement reference electrical signal output by the displacement reference electrode unit is a displacement reference current signal, and inputting the displacement reference current signal to a signal detection circuit can obtain a displacement reference voltage signal.

[0098] In operation S640, the displacement reference electrical signal is input to a closed-loop feedback circuit.

[0099] According to an embodiment of the present disclosure, the displacement reference voltage signal is input to the closed-loop feedback circuit.

[0100] In operation S650, based on the displacement reference electrical signal, the closed-loop feedback circuit adjusts the voltage size of the excitation to obtain the wafer-level packaged electric field sensor with constant sensitivity.

[0101] According to an embodiment of the present disclosure, the closed-loop feedback circuit adjusts the voltage size of the excitation according to the voltage size of the displacement reference voltage signal, so that the working state of the movable structure of the wafer-level electric field sensor can always be in a resonant state, thereby maintaining the output parameter of the wafer-level packaged electric field sensor in a stable state, for example, making the output sensitivity of the sensor a predetermined value.

[0102] In operation S660, in response to the vibration of the first comb structure of the wafer-level packaged electric field sensor with constant sensitivity, the electric field sensing electrode unit generates and outputs an induced electrical signal based on the charge induction principle.

[0103] According to an embodiment of the present disclosure, in the case that the output sensitivity of the wafer-level packaged electric field sensor is constant, the electric field sensing electrode unit generates and outputs an induced current signal based on the charge induction principle and the capacitance change amount, and the displacement reference electrode unit generates and outputs a displacement reference current signal.

[0104] According to an embodiment of the present disclosure, the induced current signal and the displacement reference current signal are passed through a signal detection circuit to obtain an induced voltage signal and a displacement reference voltage signal.

[0105] In operation S670, the induced electrical signal and the displacement reference electrical signal are compared and output to obtain the electric field strength of the electric field to be measured.

[0106] According to an embodiment of the present disclosure, the induced voltage signal and the displacement reference voltage signal output by the wafer-level packaged electric field sensor with constant output sensitivity are compared and output, and the ratio obtained is the electric field strength of the electric field to be measured.

[0107] According to an embodiment of the present disclosure, while the induced voltage signal and the displacement reference voltage signal output by the wafer-level packaged electric field sensor with constant output sensitivity are compared and output, the induced voltage signal and the displacement reference voltage signal can also be output in the form of a differential signal (differential signal), so that common mode error can be eliminated according to the differential signal.

[0108] According to the embodiment of the present disclosure, the wafer-level packaged electric field sensor is placed in the to-be-measured electric field, an initial excitation is applied to the driving structure unit of the wafer-level packaged electric field sensor by using the excitation circuit, the first comb structure and the second comb structure in the movable structure unit are driven to vibrate by the driving structure unit, based on the charge induction principle and the capacitance change amount, the electric field induction electrode unit and the displacement reference electrode unit respectively output an induced current signal and a displacement reference current signal, the induced electric signal and the displacement reference current signal are input into the signal detection circuit to be converted to obtain an induced voltage signal and a displacement reference voltage signal, while the electric field intensity of the to-be-measured electric field is obtained by comparing and outputting the induced voltage signal and the displacement reference voltage signal, the displacement reference voltage signal is input into the closed-loop feedback circuit, and the closed-loop feedback circuit adjusts the voltage size of the excitation according to the input current displacement reference voltage signal, so as to modulate the excitation applied to the driving structure unit of the wafer-level packaged electric field sensor, so that the sensitivity of the wafer-level packaged electric field sensor output is constant, the sensitivity stability is maintained, and the common-mode error is eliminated.

[0109] According to the embodiment of the present disclosure, by placing the wafer-level packaged electric field sensor in the to-be-measured electric field, an excitation is applied to the driving structure unit of the wafer-level packaged electric field sensor to make the movable structure unit vibrate, in response to the vibration of the second comb structure in the movable structure unit, the displacement reference electrode unit generates and outputs a displacement reference electric signal according to the capacitance change amount between the second comb structure and the comb structure of the displacement reference electrode unit, the displacement reference electric signal is input into the closed-loop feedback circuit, based on the displacement reference electric signal, the closed-loop feedback circuit adjusts the voltage size of the excitation, to obtain a wafer-level packaged electric field sensor with constant sensitivity, in response to the vibration of the first comb structure of the wafer-level packaged electric field sensor with constant sensitivity, based on the charge induction principle, the electric field induction electrode unit generates and outputs an induced electric signal, the induced electric signal and the displacement reference electric signal are compared and output to obtain the electric field intensity of the to-be-measured electric field, which realizes the accurate measurement of the electric field intensity of the to-be-measured electric field, and by adjusting the size of the excitation according to the displacement reference electric signal by using the closed-loop feedback circuit, the wafer-level packaged electric field sensor can be controlled to measure the electric field intensity of the to-be-measured electric field with constant output sensitivity, the stability of the output sensitivity of the wafer-level packaged electric field sensor is maintained, the common-mode error is eliminated by combining the output differential signal, further, in combination with the selection of the resonator array of the movable structure unit inside the wafer-level packaged electric field sensor, the sensitivity of the wafer-level packaged electric field sensor can be adjusted to measure the to-be-measured electric field with different accuracy by using the wafer-level packaged electric field sensor.

[0110] Figure 7 A flowchart of a preparation method of a wafer-level packaged electric field sensor according to an embodiment of the present disclosure is schematically shown.

[0111] As Figure 7As shown, the method for manufacturing the wafer-level packaged electric field sensor can include operations S710-S750.

[0112] In operation S710, a recess is etched in the device layer of the silicon-on-insulator by using a photolithography etching process, to obtain a cover plate containing the recess.

[0113] According to an embodiment of the present disclosure, the recess can be provided with an electric field enhancement structure.

[0114] In operation S720, an adsorbent is deposited on the inner surface of the recess by using an evaporation process, to obtain a wafer-level packaged cover plate.

[0115] According to an embodiment of the present disclosure, the adsorbent can be a metal adsorbent such as Zr, Ti, V, etc., and the adsorbent can also be a nano-adsorbent.

[0116] In operation S730, the device layer of the second silicon-on-insulator is etched by using a photolithography etching process, to obtain a substrate connected with a sensitive structure.

[0117] According to an embodiment of the present disclosure, the second silicon-on-insulator is a substrate, and the device layer of the substrate is etched by using a photolithography etching process, to obtain a substrate connected with a sensitive structure.

[0118] In operation S740, the silicon oxide layer in the substrate connected with the sensitive structure is etched by using a wet etching process, to release the sensitive structure in the substrate, so as to facilitate free vibration of the sensitive structure.

[0119] According to an embodiment of the present disclosure, by releasing the sensitive structure, in the case that an excitation is applied to the driving structure unit, the driving structure unit can drive the comb structure in the sensitive structure to vibrate, so as to facilitate the electric field sensing electrode unit and the displacement reference electrode unit to output an induced electric signal and a displacement reference electric signal respectively.

[0120] In operation S750, after the wafer-level packaged cover plate and the substrate are aligned, an anodic bonding or silicon-silicon bonding operation is performed, to obtain a wafer-level packaged electric field sensor.

[0121] According to an embodiment of the present disclosure, the bonding manner is not limited to an anodic bonding or silicon-silicon bonding, and can also include other bonding manners, which are not limited herein.

[0122] According to embodiments of this disclosure, a groove is etched into the device layer of silicon on a first insulator using photolithography to obtain a cover plate containing the groove. A getter is deposited on the inner surface of the groove using an evaporation process to obtain a wafer-level packaged cover plate. The device layer of silicon on a second insulator is etched using photolithography to obtain a substrate with a connected sensitive structure. The silicon oxide layer in the substrate with the connected sensitive structure is etched using a wet etching process to release the sensitive structure in the substrate. After aligning the wafer-level packaged cover plate with the substrate, anodic bonding or silicon-silicon bonding is performed to obtain a wafer-level packaged electric field sensor. This process realizes the fabrication of a wafer-level packaged electric field sensor, improves the fabrication success rate, and reduces the fabrication difficulty of the sensor. The wafer-level packaged electric field sensor fabricated by the above method can be combined with a closed-loop feedback circuit to achieve sensitivity self-compensation measurement, so that the sensitivity remains stable.

[0123] Figure 8 The illustration shows a schematic diagram of a method for fabricating a wafer-level packaged electric field sensor according to an embodiment of the present disclosure.

[0124] like Figure 8 As shown, Figure 8 The fabrication method of a wafer-level packaged electric field sensor is shown. White layer 801 represents a silicon layer, shaded layer 802 represents a getter, and shaded layer 803 represents silicon dioxide. First, a groove is etched into the device layer of silicon on a first insulator using photolithography to obtain a cover plate (a) containing the groove. Then, the getter is deposited on the inner surface of the groove using an evaporation process to obtain a wafer-level packaged cover plate (b). While preparing the wafer-level packaged cover plates (a) to (b), the device layer of silicon on a second insulator can be etched using photolithography to obtain a substrate (c) with a connected sensitive structure. Then, the silicon oxide layer in the substrate with the connected sensitive structure is etched using a wet etching process to release the sensitive structure in the substrate (d). Finally, the wafer-level packaged cover plate and the substrate are aligned and anodic bonding or silicon-silicon bonding is performed to obtain a wafer-level packaged electric field sensor (e).

[0125] According to embodiments of this disclosure, the electric field sensor may include a wafer-level packaged electric field sensor prepared by the preparation method described above.

[0126] According to embodiments of this disclosure, the wafer-level packaged electric field sensor described above can also be fabricated by another method, which may include the following operations.

[0127] According to an embodiment of this disclosure, two first grooves are etched on a silicon wafer using a photolithography etching process to obtain a cover plate containing the two first grooves.

[0128] According to an embodiment of the present disclosure, glass medium is filled in the two first grooves of the cover plate by using a glass reflow technology, and the upper and lower excess glass layers and silicon layers are removed by grinding and polishing, so that the glass medium in the first groove penetrates through the cover plate, and the glass medium is an insulating medium layer.

[0129] According to an embodiment of the present disclosure, two second grooves and an electric field enhancement structure are etched on a silicon wafer by using a photolithography etching process, and the electric field enhancement structure is thinned by using a photolithography etching process, to obtain a cover plate connected with the electric field enhancement structure.

[0130] According to an embodiment of the present disclosure, an adsorbent is deposited on the inner surfaces of the two second grooves and the outer surface of the electric field enhancement structure by using an evaporation process, to obtain a wafer-level packaging cover plate.

[0131] According to an embodiment of the present disclosure, the device layer of the silicon-on-insulator is etched by using a photolithography etching process, to obtain a substrate connected with a sensitive structure.

[0132] According to an embodiment of the present disclosure, the silicon oxide layer in the substrate connected with the sensitive structure is etched by using a wet etching process, to release the sensitive structure in the substrate, so as to facilitate the free vibration of the sensitive structure.

[0133] According to an embodiment of the present disclosure, after the wafer-level packaging cover plate is aligned with the substrate, an anodic bonding or silicon-silicon bonding operation is performed, to obtain a wafer-level packaging electric field sensor.

[0134] According to an embodiment of the present disclosure, the bonding mode is not limited to an anodic bonding or silicon-silicon bonding, and can also include other bonding modes, which are not limited herein.

[0135] According to an embodiment of the present disclosure, the wafer-level packaging electric field sensor can be prepared by using the above preparation method, the electric field is concentrated by the electric field enhancement structure, so as to enhance the sensitivity, the applied excitation is adjusted according to the displacement reference electric signal by using an additional closed-loop feedback circuit, so as to stabilize the output sensitivity of the sensor, and the common-mode error is eliminated according to the output differential signal.

[0136] According to an embodiment of the present disclosure, the electric field sensor can include the wafer-level packaging electric field sensor prepared by using the preparation method as described above.

[0137] Figure 9 A schematic diagram of a preparation method of a wafer-level packaging electric field sensor according to another embodiment of the present disclosure is schematically shown.

[0138] As Figure 9 shown, Figure 9The preparation method of the wafer-level packaged electric field sensor is shown, the white layer 901 represents a silicon layer, the shaded layer 902 represents a getter, the shaded layer 903 represents silicon dioxide, and the shaded layer 904 represents glass. Two first grooves are etched on a silicon wafer by using a photolithography etching process to obtain a cover plate containing two first grooves (a), then glass medium is filled into the two first grooves of the cover plate by using a glass reflow technology, and the upper and lower excess glass layers and silicon layers are removed by grinding and polishing, so that the glass medium in the first groove penetrates through the cover plate (b), two second grooves and an electric field enhancement structure are etched on the silicon wafer by using a photolithography etching process, and the electric field enhancement structure is thinned by a photolithography etching process to obtain a cover plate connected with the electric field enhancement structure (c), the getter is deposited on the inner surface of the two second grooves and the outer surface of the electric field enhancement structure by using an evaporation process to obtain a wafer-level packaged cover plate (d), while the wafer-level packaged cover plate (a)~(d) is prepared, the device layer of the silicon-on-insulator can be etched by using a photolithography etching process to obtain a substrate connected with a sensitive structure (e), then the silicon oxide layer in the substrate connected with the sensitive structure is etched by using a wet etching process to release the sensitive structure in the substrate (f), finally, the wafer-level packaged cover plate and the substrate are aligned and then subjected to an anodic bonding or silicon-silicon bonding operation to obtain a wafer-level packaged electric field sensor (g).

[0139] Those skilled in the art can understand that the features described in various embodiments and / or claims of the present disclosure can be combined or / and integrated in various combinations, even if such combinations or integrations are not explicitly described in the present disclosure. In particular, the features described in various embodiments and / or claims of the present disclosure can be combined and / or integrated in various combinations without departing from the spirit and teachings of the present disclosure. All such combinations and / or integrations fall within the scope of the present disclosure.

[0140] The above specific embodiments further detail the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above are only specific embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A wafer level packaged electric field sensor, comprising: a substrate for supporting a sensitive structure and a wafer level packaged cover plate, a surface of the substrate being provided with an anchor point; a sensitive structure fixed above the substrate through the anchor point, the sensitive structure comprising a plurality of electric field sensing electrode units and a plurality of displacement reference electrode units respectively arranged between a driving structure unit and the electric field sensing electrode units within the sensitive structure, for generating an induced electric signal by the electric field sensing electrode units under the condition of applying an excitation to the sensitive structure, and generating a displacement reference electric signal by the displacement reference electrode units according to a capacitance variation amount, so as to determine an electric field measurement result according to a ratio of the induced electric signal and the displacement reference electric signal, and to compensate a common mode error of the wafer level packaged electric field sensor according to a plurality of induced electric signals output in a differential form and a plurality of displacement reference electric signals output in a differential form, and to improve an output sensitivity of the wafer level packaged electric field sensor; a wafer level packaged cover plate arranged above the sensitive structure, for forming a sealed chamber together with the substrate, so as to make the sensitive structure in the sealed chamber in a vacuum working environment, so as to improve a quality factor of the wafer level packaged electric field sensor; wherein the sensitive structure further comprises a movable structure unit, a resonator comprising an elastic beam within the movable structure unit and a first comb structure and / or a second comb structure, the movable structure unit being a single resonator structure or a multi-resonator coupling structure, the single resonator structure comprising one resonator for vibrating the first comb structure and the second comb structure with the same amplitude in response to a driving of the driving structure unit within the sensitive structure, so as to make the output sensitivity of the wafer level packaged electric field sensor a predetermined value; the multi-resonator coupling structure comprising a plurality of resonators, in the case of containing a plurality of movable structure units, elastic beams of the plurality of movable structure units being connected to at least one coupling structure, for vibrating the first comb structure and the second comb structure with different amplitudes in response to the driving of the driving structure unit based on a mode localization principle, so as to improve the output sensitivity of the wafer level packaged electric field sensor.

2. The sensor of claim 1, wherein, the sensitive structure further comprises a driving structure unit and a movable structure unit; the driving structure unit is arranged on one side of the movable structure unit for driving the movable structure unit to vibrate; the movable structure unit is arranged above a center of the substrate for vibrating in response to the driving structure unit, so that the electric field sensing electrode units and the displacement reference electrode units generate the induced electric signal and the displacement reference electric signal respectively.

3. The sensor of claim 2, wherein, the movable structure unit comprises a first comb structure and a second comb structure, the electric field sensing electrode units generate an induced electric signal, and the displacement reference electrode units generate a displacement reference electric signal, comprising: The first comb structure is arranged on one side of the electric field sensing electrode unit and is differentially staggered with the comb structure of the electric field sensing electrode unit, and the electric field sensing electrode unit generates and outputs the induced electric signal based on the charge induction principle in response to the vibration of the first comb structure. The second comb structure is arranged on one side of the displacement reference electrode unit and is staggered with the comb structure of the displacement reference electrode unit, and the displacement reference electrode unit generates and outputs the displacement reference electric signal according to the capacitance change between the second comb structure and the comb structure of the displacement reference electrode unit in response to the vibration of the second comb structure.

4. The sensor of claim 1, wherein, The wafer-level packaging cover plate comprises a cover plate, an insulating medium layer and an electric field enhancement structure; The lower surface of the cover plate is fixed above the substrate through the insulating medium layer, so as to form a sealed cavity with the insulating medium layer and the substrate; The electric field enhancement structure is arranged on the upper surface of the cover plate or the lower surface of the cover plate, and the electric field enhancement structure is located directly above the sensitive structure, so as to concentrate the electric field to be measured and enhance the electric field intensity acting on the sensitive structure.

5. The sensor of claim 1, wherein, The movable structure unit further comprises an elastic beam arranged on both sides of the first comb structure and the second comb structure, for supporting the first comb structure and the second comb structure, and the elastic beam is one of a straight beam, a folded beam and a curved beam, or a combination thereof.

6. An electric field detection method using the wafer-level packaging electric field sensor according to any one of claims 1-5, comprising: placing the wafer-level packaging electric field sensor in an electric field to be measured; applying an excitation to the driving structure unit of the wafer-level packaging electric field sensor to vibrate the movable structure unit; generating and outputting a displacement reference electric signal by the displacement reference electrode unit according to the capacitance change between the second comb structure and the comb structure of the displacement reference electrode unit in response to the vibration of the second comb structure; inputting the displacement reference electric signal into a closed-loop feedback circuit; adjusting the voltage of the excitation by the closed-loop feedback circuit based on the displacement reference electric signal to obtain the wafer-level packaging electric field sensor with constant sensitivity; generating and outputting an induced electric signal by the electric field sensing electrode unit based on the charge induction principle in response to the vibration of the first comb structure of the wafer-level packaging electric field sensor with constant sensitivity; comparing and outputting the induced electric signal and the displacement reference electric signal to obtain the electric field intensity of the electric field to be measured.

7. A preparation method for preparing the wafer-level packaging electric field sensor according to any one of claims 1-5, comprising: etching a groove in a first SOI device layer by a photolithography etching process to obtain a cover plate containing the groove; depositing a getter on the inner surface of the groove by an evaporation process to obtain a wafer-level packaging cover plate; etching a second SOI device layer by a photolithography etching process to obtain a substrate connected with a sensitive structure, wherein the second SOI is the substrate. The silicon oxide layer in the substrate connected with the sensitive structure is etched by using a wet etching process to release the sensitive structure in the substrate so as to facilitate free vibration of the sensitive structure; After the wafer level packaging cover plate is aligned with the substrate, an anodic bonding or silicon-silicon bonding operation is performed to obtain the wafer level packaging electric field sensor.

8. An electric field sensor comprising: The wafer level packaging electric field sensor according to any one of claims 1 to 5 or the wafer level packaging electric field sensor obtained by the preparation method of claim 7.

9. The electric field sensor of claim 8, wherein, The electric field sensor further comprises a two-dimensional or three-dimensional electric field sensor composed of a plurality of electric field sensitive structures for measuring a two-dimensional or three-dimensional electric field or voltage.

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