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

Abstract

The invention provides a wafer-level packaging 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 packaging electric field sensor comprises a substrate used for supporting a sensitive structure and a wafer-level packaging cover plate; the sensitive structure is fixed above the substrate through anchor points, comprises an electric field induction electrode unit and a displacement reference electrode unit, and is used for generating an induction electric signal by the electric field induction electrode unit and generating a displacement reference electric signal by the displacement reference electrode unit under the condition that excitation is applied to the sensitive structure; therefore, the common modulus error of the wafer-level packaging electric field sensor can be compensated according to the induction electric signal and the displacement reference electric signal, and the output sensitivity of the wafer-level packaging electric field sensor can be improved. And the wafer-level packaging cover plate is arranged above the sensitive structure and is used for forming a closed cavity together with the substrate, so that the sensitive structure in the closed cavity 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 sensors, and more specifically to a wafer-level packaged electric field sensor, an electric field detection method, a preparation method, and a sensor. Background Art

[0002] Since the electric field sensors developed based on micro-electromechanical systems (MEMS) have the advantages of small size, light weight and low cost, they are widely used in many fields, such as aerospace, meteorology, electricity, industrial production, etc. However, the existing MEMS electric field sensors based on the charge induction principle are affected by external environments such as temperature, resulting in low output sensitivity and resolution, which cannot meet the high requirements of existing electric field sensors.

[0003] In the process of realizing the above-mentioned inventive concept, the inventors found that in the related technology, since the existing electric field sensors are affected by the common mode of the external environment such as temperature, the output sensitivity and output resolution of the electric field sensors are poor, which reduces the accuracy and stability of the electric field sensors in measuring the electric field. In addition, the high damping working environment of the driving structure and the crosstalk noise introduced in the process of applying the excitation voltage to the driving structure will further reduce the output sensitivity and output resolution of the electric field sensor. Summary of the invention

[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 a sensor.

[0005] According to a first aspect of the present disclosure, a wafer-level packaged electric field sensor is provided, comprising: a substrate, used to support a sensitive structure and a wafer-level package cover plate, wherein an anchor point is arranged on the surface of the substrate; a sensitive structure, fixed above the substrate through the anchor point, wherein the sensitive structure comprises an electric field sensing electrode unit and a displacement reference electrode unit, wherein when 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, 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, thereby improving the output sensitivity of the wafer-level packaged electric field sensor; a wafer-level package cover plate, arranged above the sensitive structure, and 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.

[0006] According to an embodiment of the present disclosure, the sensitive structure also includes 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 respond to the vibration generated by the driving structure unit, so that the electric field sensing electrode unit and the displacement reference electrode unit generate a sensing electrical signal and a displacement reference electrical signal respectively.

[0007] According to an embodiment of the present disclosure, the movable structure unit includes a first comb tooth structure and a second comb tooth structure, the electric field sensing electrode unit generates an induced electrical signal, and the displacement reference electrode unit generates a displacement reference electrical signal, including: the first comb tooth structure is arranged on one side of the electric field sensing electrode unit, and is differentially staggered with the comb tooth structure of the electric field sensing electrode unit, and is used to respond to the vibration of the first comb tooth structure. Based on the charge induction principle, the electric field sensing electrode unit generates and outputs the induced electrical signal; the second comb tooth structure is arranged on one side of the displacement reference electrode unit, and is staggered with the comb tooth structure of the displacement reference electrode unit. In response to the vibration of the second comb tooth structure, the capacitance between the second comb tooth structure and the comb tooth structure of the displacement reference electrode unit is changed, and according to the capacitance change, the displacement reference electrode unit generates and outputs the displacement reference electrical signal.

[0008] According to an embodiment of the present disclosure, a wafer-level packaging cover plate includes a cover plate, an insulating dielectric layer and an electric field enhancement structure; the lower surface of the cover plate is fixed above the substrate through the insulating dielectric layer, and is used to form a closed chamber with the insulating dielectric 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 strength acting on the sensitive structure.

[0009] According to an embodiment of the present disclosure, the movable structural unit also includes an elastic beam, which is arranged on both sides of the first comb tooth structure and the second comb tooth structure for supporting the first comb tooth structure and the second comb tooth 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 includes an elastic beam and a first comb tooth structure and / or a second comb tooth structure, the movable structure unit is a single resonator structure or a multi-resonator coupling structure, the single resonator structure includes a resonator, which is used to respond to the drive of the driving structure unit, and the first comb tooth structure and the second comb tooth structure vibrate with the same amplitude, so that the output sensitivity of the wafer-level packaging electric field sensor is a predetermined value; the multi-resonator coupling structure includes multiple resonators, which are used to respond to the drive of the driving structure unit, and the first comb tooth structure and the second comb tooth structure vibrate with different amplitudes, 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 measured; applying excitation to a driving structure unit of the wafer-level packaged electric field sensor to vibrate a movable structure unit; in response to the vibration of a second comb-tooth structure in the movable structure unit, the displacement reference electrode unit generates and outputs a displacement reference electrical signal according to a capacitance change between the second comb-tooth structure and the comb-tooth structure of a displacement reference electrode unit; inputting the displacement reference electrical signal into a closed-loop feedback circuit; based on the displacement reference electrical signal, the closed-loop feedback circuit adjusts the magnitude of the excitation voltage to obtain a wafer-level packaged electric field sensor with constant sensitivity; in response to the vibration of a first comb-tooth 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 a charge induction principle; 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.

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

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

[0014] 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, for measuring a two-dimensional or three-dimensional electric field or voltage.

[0015] According to the wafer-level package electric field sensor, electric field detection method, preparation method and sensor disclosed in the present invention, the wafer-level package electric field sensor includes a substrate, a sensitive structure and a wafer-level package cover plate, the sensitive structure is fixed on the substrate through an anchor point, the wafer-level package cover plate is arranged above the sensitive structure, and the sensitive structure includes an electric field sensing electrode unit and a displacement reference electrode unit. When 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. It is achieved that when detecting the electric field to be measured, an accurate measurement result corresponding to the electric field to be measured can be obtained according to the result of comparing the induced electric signal and the displacement reference electric signal, thereby improving the measurement efficiency. Moreover, while the electric field sensing electrode unit generates the induced electric signal and the displacement reference electrode unit generates the displacement reference electric signal, the induced electric signal and the displacement reference electric signal can be output in a differential form. The differential signal output by the electric field sensing electrode unit and the displacement reference electrode unit eliminates the common mode error caused by external environments such as temperature, thereby avoiding different measurement environments from reducing the output sensitivity and resolution, maintaining the stability of the sensor device parameters such as the output sensitivity and resolution of the wafer-level electric field sensor, and improving the stability of the wafer-level packaged electric field sensor for measurement accuracy.

[0016] According to the embodiments of the present disclosure, further, by arranging a wafer-level packaging cover plate above the sensitive structure, a closed chamber is formed between the wafer-level packaging cover plate and the substrate, and the sensitive structure is located in the closed chamber, and the closed chamber is a vacuum environment, so that the sensitive structure can work in a vacuum working 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, and reducing the crosstalk noise generated by the excitation applied to the electric field sensing electrode unit. Moreover, since the quality factor is proportional to the resonance amplitude, the amplitude of the sensitive structure is increased while the quality factor is increased, so that the larger the electrical signal output by the wafer-level electric field sensor under the drive of the same excitation, the higher the sensitivity.

[0017] According to the embodiments of the present disclosure, further, the wafer-level electric field sensor of the present disclosure can be applicable to electric field measurement environments in various fields, and can achieve accurate measurement of electric fields in a variety of environments. The wafer-level packaging process can also improve the manufacturing efficiency of mass production of sensors, and has a high application value. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0019] Figure 1The schematic diagram of the structure of the wafer-level packaged electric field sensor according to the embodiment of the present disclosure is shown;

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

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

[0022] Figure 4 A schematic diagram schematically shows a sensitive structure of a wafer-level packaged electric field sensor in which the movable structure is a multi-resonator array according to an embodiment of the present disclosure;

[0023] 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 schematically shown;

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

[0025] Figure 7 A flow chart schematically shows a method for preparing a wafer-level packaged electric field sensor according to an embodiment of the present disclosure;

[0026] Figure 8 A schematic diagram schematically shows a method for preparing a wafer-level packaged electric field sensor according to an embodiment of the present disclosure;

[0027] Fig. 9 A schematic diagram of a method for preparing a wafer-level packaged electric field sensor according to another embodiment of the present disclosure is schematically shown.

[0028] Reference numerals:

[0029] Substrate 110, sensitive structure 120, wafer-level packaging cover 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 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. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0031] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0032] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0033] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0034] In the technical solution of the present invention, the user information (including but not limited to user personal information, user image information, user device information, such as location information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved are all information and data authorized by the user or fully authorized by all parties, and the collection, storage, use, processing, transmission, provision, disclosure and application of the relevant data comply with relevant laws, regulations and standards, take necessary confidentiality measures, do not violate public order and good morals, and provide corresponding operation entrances for users to choose to authorize or refuse.

[0035] Since the electric field sensors developed based on micro-electromechanical systems (MEMS) have the advantages of small size, light weight and low cost, they are widely used in many fields, such as aerospace, meteorology, electricity, industrial production, etc. Existing MEMS electric field sensors are mainly designed based on the charge induction principle. However, when using existing electric field sensors to measure the electric field, due to the low sensitivity of the electric field sensors, accurate electric field detection results cannot be obtained.

[0036] Furthermore, researchers conducted a deeper research and development on electric field sensors designed based on the charge induction principle in order to meet the current high demand for electric field sensors. During the research and development process, researchers found that in the related technology, the output sensitivity and output resolution of the electric field sensors are poor because the existing electric field sensors are affected by the common mode of the external environment such as temperature, which reduces the accuracy and stability of the electric field measurement by the electric field sensors. In addition, the high damping working environment of the driving structure and the crosstalk noise introduced in the process of applying the excitation voltage to the driving structure will further reduce the technical problems of the output sensitivity and output resolution of the electric field sensors.

[0037] In view of this, an embodiment of the present disclosure provides a wafer-level packaged electric field sensor, comprising: a substrate, used to support a sensitive structure and a wafer-level package cover plate, the surface of the substrate being provided with anchor points; a sensitive structure, fixed above the substrate through the anchor points, the sensitive structure comprising an electric field sensing electrode unit and a displacement reference electrode unit, for when 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, 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, thereby improving the output sensitivity of the wafer-level packaged electric field sensor; a wafer-level package cover plate, arranged above the sensitive structure, and used to form a closed chamber together with the substrate, so that the sensitive structure in the closed chamber is in a vacuum working environment, so as to improve the quality factor of the wafer-level packaged electric field sensor.

[0038] The following will be passed Figure 1~Figure 5 The wafer-level packaged electric field sensor of the disclosed embodiment is described in detail.

[0039] According to an embodiment of the present disclosure, a wafer-level package electric field sensor may include a substrate, a sensitive structure, and a wafer-level package cover.

[0040] According to an embodiment of the present disclosure, a substrate may be used to support a sensitive structure and a wafer-level packaging cover plate, and a plurality of anchor points may be provided on the surface of the substrate.

[0041] According to an embodiment of the present disclosure, a sensitive structure is fixed above a substrate through an anchor point, and the sensitive structure includes an electric field sensing electrode unit and a displacement reference electrode unit. When 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, 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, thereby improving the output sensitivity of the wafer-level packaged electric field sensor.

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

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

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

[0045] According to an embodiment of the present disclosure, a wafer-level package electric field sensor includes a substrate, a sensitive structure and a wafer-level package cover plate, wherein the sensitive structure is fixed on the substrate through an anchor point, and the wafer-level package cover plate is arranged above the sensitive structure, and the sensitive structure includes an electric field sensing electrode unit and a displacement reference electrode unit. When the sensitive structure is stimulated, the electric field sensing electrode unit generates an induced electric signal, and the displacement reference electrode unit generates a displacement reference electric signal. It is realized that when the electric field to be measured is detected, an accurate measurement result corresponding to the electric field to be measured can be obtained according to the result of the comparison between the induced electric signal and the displacement reference electric signal, thereby improving the measurement efficiency, and while the electric field sensing electrode unit generates the induced electric signal and the displacement reference electrode unit generates the displacement reference electric signal, the induced electric signal and the displacement reference electric signal can be output in a differential form, and the differential signal output by the electric field sensing electrode unit and the displacement reference electrode unit eliminates the common mode error caused by the external environment such as temperature, avoids different measurement environments from reducing the output sensitivity and resolution, maintains the stability of the sensor device parameters such as the output sensitivity and resolution of the wafer-level electric field sensor, and improves the stability of the wafer-level package electric field sensor with improved measurement accuracy.

[0046] According to the embodiments of the present disclosure, further, by arranging a wafer-level packaging cover plate above the sensitive structure, a closed chamber is formed between the wafer-level packaging cover plate and the substrate, and the sensitive structure is located in the closed chamber, and the closed chamber is a vacuum environment, so that the sensitive structure can work in a vacuum working 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, and reducing the crosstalk noise generated by the excitation applied to the electric field sensing electrode unit. Moreover, since the quality factor is proportional to the resonance amplitude, the amplitude of the sensitive structure is increased while the quality factor is increased, so that the larger the electrical signal output by the wafer-level electric field sensor under the drive of the same excitation, the higher the sensitivity.

[0047] According to the embodiments of the present disclosure, further, the wafer-level electric field sensor of the present disclosure can be applicable to electric field measurement environments in various fields, and can achieve accurate measurement of electric fields in a variety of environments. The wafer-level packaging process can also improve the manufacturing efficiency of mass production of sensors, and has a high application value.

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

[0049] like Figure 1 As shown, Figure 1 The structure of a wafer-level packaged electric field sensor is shown. The wafer-level packaged electric field sensor includes a substrate 110, a sensitive structure 120 and a wafer-level package cover plate 130. A plurality of anchor points 111 are arranged on the substrate. The sensitive structure 120 is arranged on the substrate 110 through the plurality of anchor points 111. The wafer-level package cover plate 130 is arranged on the substrate 110 and forms a closed chamber together with the substrate 110, so that the sensitive structure 120 is in the closed chamber. The sensitive structure 120 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 an embodiment of the present disclosure, the sensitive structure further includes a driving structure unit and a movable structure unit.

[0051] According to an embodiment of the present disclosure, the driving structure unit may be disposed on one side of the movable structure unit to drive the movable structure unit to generate vibration.

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

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

[0054] According to an embodiment of the present disclosure, the movable structure unit is disposed 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 a sensing electric signal and a displacement reference electric signal respectively.

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

[0056] According to an embodiment of the present disclosure, the sensitive structure may further include a driving structure unit and a movable structure unit. The driving structure unit may be arranged on one side or both sides of the movable structure unit, and the movable structure unit may be arranged above the center of the substrate. The movable structure unit may vibrate by applying an excitation of a certain voltage magnitude to the driving structure unit, so that the electric field induction 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. While the vibration of the movable structure unit is realized, the electrode unit outputs an electric signal for detecting or eliminating the working modulus error.

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

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

[0059] According to an embodiment of the present disclosure, when excitation is applied to the driving structure unit 220, the movable structure unit 210 vibrates in response to the driving structure unit 220, thereby causing the comb-tooth structure that is staggered with the electric field sensing electrode unit 230 and the displacement reference electrode unit 240 (differential) to vibrate. Based on the charge induction principle and the capacitance change, the electric field sensing electrode unit 230 outputs an induced electrical signal, and the displacement reference electrode unit 240 outputs a displacement reference electrical signal.

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

[0061] According to an embodiment of the present disclosure, the first comb-tooth structure is arranged on one side of the electric field sensing electrode unit, and is differentially staggered with the comb-tooth structure of the electric field sensing electrode unit, so that in response to the vibration of the first comb-tooth structure, the electric field sensing electrode unit generates and outputs an induced electrical signal based on the charge induction principle.

[0062] According to the embodiments of the present disclosure, the comb-tooth structure can increase the sensing area so as to enhance the output induced electrical signal. Furthermore, by differentially staggering the electrode comb teeth of the electric field sensing electrode unit and the comb-tooth structure, the output induced electrical signal can also be enhanced.

[0063] According to an embodiment of the present disclosure, the second comb tooth structure is arranged on one side of the displacement reference electrode unit and is arranged alternately with the comb tooth structure of the displacement reference electrode unit. It is used to change the capacitance between the second comb tooth structure and the comb tooth structure of the displacement reference electrode unit in response to the vibration of the second comb tooth structure. According to the capacitance change, the displacement reference electrode unit generates and outputs a displacement reference electrical signal.

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

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

[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 all be fixed on the substrate through anchor points.

[0067] According to an embodiment of the present disclosure, the movable structure unit may include at least one elastic beam, at least one first comb tooth structure and at least one second comb tooth structure. For example, two elastic beams, two first comb tooth structures and four second comb tooth structures may be included in the movable structure, the two first comb tooth structures are arranged above the center of the substrate, the first second comb tooth structure may be located on the left side of the first comb tooth structure, the second second comb tooth structure may be located on the right side of the first comb tooth structure, the first elastic beam is arranged on the left side of the first second comb tooth structure, the second elastic beam is arranged on the right side of the second second comb tooth structure, and the two elastic beams, two first comb tooth structures and two second comb tooth 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 may include a first comb tooth structure, a second comb tooth structure and an elastic beam. The elastic beam may be arranged on both sides of the first comb tooth structure and the second comb tooth structure. While supporting the first comb tooth structure and the second comb tooth structure, the elastic beam may also allow the first comb tooth structure and the second comb tooth structure to have a certain space to vibrate with a predetermined amplitude when vibration is generated. The first comb tooth structure and the comb tooth structure of the electric field sensing electrode unit are differentially staggered, and the second comb tooth structure and the comb tooth structure of the displacement reference electrode unit are staggered. By applying excitation to the driving structure unit, the first comb tooth structure and the second comb tooth structure in the movable structure unit are driven to vibrate, thereby avoiding the driving and In the push detection, based on the charge induction principle, the electric field sensing electrode unit on one side of the first comb tooth structure outputs an induced electric signal, and based on the capacitance change between the comb tooth structures of the second comb tooth structure and the displacement reference electrode unit, the displacement reference electrode unit outputs a displacement reference electric signal, so that when the first comb tooth structure and the second comb tooth structure of 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. Furthermore, through the comb tooth structure and the staggered arrangement, the output induced electric signal can be enhanced, and the capacitance change can be increased, 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 according to an embodiment of the present disclosure is schematically shown.

[0070] like Figure 3 As shown, Figure 3 The movable structure of the wafer-level packaged electric field sensor is shown, and the movable structure includes an elastic beam 310, a first comb tooth structure 320 and a second comb tooth structure 330. As shown in the figure, Figure 3The movable structure shown includes two elastic beams 310, two first comb-tooth structures 320 and four second comb-tooth structures 330. The elastic beams 310, the first comb-tooth structures 320 and the second comb-tooth structures 330 are all located above the substrate. The first elastic beam 310 is arranged on the left side of the first second comb-tooth structure 330, the second elastic beam 310 is arranged on the right side of the fourth second comb-tooth structure 330, and the first first comb-tooth structure 320 is arranged above the second second comb-tooth structure 330 and the third second comb-tooth structure 330, and the second comb-tooth structures 330 are arranged on the right side of the fourth second comb-tooth structure 330. 0, the second first comb tooth structure 320 is arranged below the second second comb tooth structure 330 and the third second comb tooth structure 330, and is connected to the first first comb tooth structure 320. By connecting the elastic beam 310, the first comb tooth structure 320 and the second comb tooth structure 330, when the driving structure unit is excited, the first comb tooth structure 320 and the second comb tooth structure 330 in the movable structure unit will vibrate, so that the electric field sensing electrode unit and the displacement reference electrode unit generate an induced electrical signal and a displacement reference electrical signal respectively.

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

[0072] According to an embodiment of the present disclosure, the single resonator structure includes a resonator for vibrating the first comb tooth structure and the second comb tooth structure with the same amplitude in response to the driving of the driving structure unit, so that the output sensitivity of the wafer-level packaged electric field sensor is a predetermined value.

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

[0074] According to an embodiment of the present disclosure, the multi-resonator coupling structure includes multiple resonators, which are used to vibrate the first comb tooth structure and the second comb tooth structure with different amplitudes in response to the drive of the driving structure unit, so as to improve the output sensitivity of the wafer-level package electric field sensor.

[0075] According to an embodiment of the present disclosure, the multiple resonators included in the multi-resonator coupling structure may be composed of an elastic beam and a first comb-tooth structure, or may be composed of an elastic beam and a second comb-tooth structure. In the multi-resonator coupling structure, the multiple resonators may be coupled through at least one coupling structure, and in response to the drive of the driving structure unit, based on the modal localization principle, the multiple resonators vibrate with amplitudes of different sizes, thereby adjusting the output sensitivity of the sensor. For example, in the case where the movable structure unit of the wafer-level packaged electric field sensor is a multi-resonator coupling structure, the movable structure unit may include two resonators, and the two resonators are connected by two coupling structures, the first resonator is composed of an elastic beam and a first comb-tooth structure, the second resonator is composed of an elastic beam and a second comb-tooth structure, the upper end between the first resonator and the second resonator is linked by the first coupling structure, and the lower end between the first resonator and the second resonator is 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 may include an elastic beam and a first comb tooth structure and / or a second comb tooth structure. The movable structural unit in the sensor may be a single resonator structure or a multi-resonator coupling structure. When the movable structural unit is a single resonator structure, in response to the drive of the driving structural unit, the first comb tooth structure and the second comb tooth structure may 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. When the movable structural unit is a multi-resonator coupling structure, in response to the drive of the driving structural unit, based on the modal localization principle, the first comb tooth structure and the second comb tooth structure may vibrate with different amplitudes, so as to adjust the output sensitivity of the wafer-level packaged electric field sensor, thereby improving the output sensitivity of the sensor.

[0078] Figure 4 The schematic diagram shows a sensitive structure of a wafer-level packaged electric field sensor in which the movable structure is a multi-resonator array according to an embodiment of the present disclosure.

[0079] like Figure 4 As shown, Figure 4The movable structure in the sensitive structure is a structure of a multi-resonator array, and the sensitive structure includes two driving structure units 220, two electric field sensing electrode units 230, two displacement reference electrode units 240, and a movable structure unit composed of two resonator arrays. The first resonator includes two elastic beams 310 and two second comb-tooth structures 330, and the second resonator includes two elastic beams 310 and two first comb-tooth structures 320. The two resonators are connected by two coupling structures 410. The comb-tooth structure of the first electric field sensing electrode unit 230 is staggered with the first second comb-tooth structure 330 in the first resonator, and the comb-tooth structure of the second electric field sensing electrode unit 230 is 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, and the second elastic beam 310 in the first resonator is located on the right side of the second comb-tooth structure 330. The first driving structure unit 220 is located on the left side of the first elastic beam 310 in the first resonator. The comb structure of the first displacement reference electrode unit 240 is differentially staggered with the first first comb structure 320 in the second resonator, the comb structure of the second displacement reference electrode unit 240 is differentially staggered with the second first comb 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 structure 320, the second elastic beam 310 in the second resonator is located on the right side of the first comb 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, a wafer-level packaging cover plate includes a cover plate, an insulating dielectric 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 an insulating dielectric layer, and is used to form a closed chamber with the insulating dielectric 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 may be made of one or more conductive materials, the insulating medium layer may be made of one or more insulating materials, or may be made of a composite material whose outermost layer is an insulating material.

[0083] According to the embodiments of the present disclosure, since crosstalk noise may be generated when excitation is applied to the electric field sensing electrode unit, 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 impact of crosstalk noise. Furthermore, since the quality factor is proportional to the resonant amplitude, the amplitude of the sensitive structure may be increased while improving the quality factor, so that the wafer-level electric field sensor outputs a larger electrical signal and has a higher sensitivity when driven by an excitation of the same magnitude.

[0084] According to an embodiment of the present disclosure, the electric field enhancement structure is arranged on the upper surface 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 strength acting on the sensitive structure.

[0085] According to an embodiment of the present disclosure, the structural shape of the electric field enhancement structure may include any one of the following: a cuboid, a cube, a frustum, a prism, a prism, a cylinder, a cone, and an irregular body.

[0086] According to an embodiment of the present disclosure, a wafer-level packaging cover plate includes a cover plate, an insulating dielectric layer and an electric field enhancement structure. The lower surface of the cover plate is fixed above the substrate through the insulating dielectric layer to form a closed chamber with the insulating dielectric 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. The electric field enhancement structure is located directly above the sensitive structure to concentrate the electric field to be measured so as to enhance the electric field strength acting on the sensitive structure. This reduces the damping of the wafer-level electric field sensor, improves the quality factor of the wafer-level electric field sensor, and reduces the impact of crosstalk noise. At the same time, the electric field strength acting on the sensitive structure is enhanced, and the amplitude of the sensitive structure is increased, so that the wafer-level electric field sensor outputs a larger electrical signal and has a higher sensitivity when driven by an excitation of the same magnitude. In addition, the wafer-level packaging process can also improve the manufacturing efficiency of mass production of sensors 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 schematically shown.

[0088] like Figure 5 As shown, Figure 5 A wafer-level packaging cover plate of a wafer-level packaging electric field sensor is shown. The wafer-level packaging cover plate includes a cover plate 510, an insulating dielectric layer 520 and an electric field enhancement structure 530. The lower surface of the cover plate 510 is connected to the insulating dielectric 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 that a closed chamber can be formed together with the substrate to put the sensitive structure in a vacuum working environment.

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

[0090] According to an embodiment of the present disclosure, the electric field sensor also 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 The flowchart of the electric field detection method according to the embodiment of the present disclosure is schematically shown.

[0092] like Figure 6 As shown, the electric field detection method of this embodiment includes operations S610 to S670.

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

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

[0095] According to an embodiment of the present disclosure, when an excitation is applied to the driving structure unit of the wafer-level package electric field sensor, the first comb tooth structure and the second comb tooth structure in the movable structure unit will both vibrate. When the movable structure unit is a single resonator structure, the first comb tooth structure and the second comb tooth structure in the movable structure unit can generate vibrations with consistent amplitudes, thereby maintaining the output sensitivity of the sensor. When the movable structure unit is a multi-resonator coupling structure, the first comb tooth structure and the second comb tooth structure in the movable structure unit can generate vibrations with inconsistent amplitudes based on the modal localization principle, thereby improving the output sensitivity of the sensor.

[0096] In operation S630, in response to vibration of the second comb-tooth structure in the movable structure unit, the displacement reference electrode unit generates and outputs a displacement reference electrical signal according to a capacitance variation between the second comb-tooth structure and the comb-tooth 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. By inputting the displacement reference current signal into a signal detection circuit, a displacement reference voltage signal can be obtained.

[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, a displacement reference voltage signal is input to a closed-loop feedback circuit.

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

[0101] According to an embodiment of the present disclosure, a closed-loop feedback circuit adjusts the excitation voltage according to the voltage of a 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 parameters 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-teeth structure of the wafer-level package electric field sensor having a constant sensitivity, the electric field sensing electrode unit generates and outputs an induced electric signal based on a charge induction principle.

[0103] According to an embodiment of the present disclosure, when the output sensitivity of the wafer-level packaged electric field sensor is constant, based on the charge induction principle and the capacitance change, the electric field sensing electrode unit generates and outputs an induction current signal, 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 electric signal and the displacement reference electric 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 output by the wafer-level package electric field sensor with constant output sensitivity and the displacement reference voltage signal are compared and output, and the obtained ratio 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 a differential form (differential signal), so that the common mode error can be eliminated according to the differential signal.

[0108] According to an embodiment of the present disclosure, a wafer-level packaged electric field sensor is placed in an electric field to be measured, and an initial excitation is applied to a driving structure unit of the wafer-level packaged electric field sensor using an excitation circuit. The driving structure unit drives the first comb tooth structure and the second comb tooth structure in the movable structure unit to vibrate. Based on the charge induction principle and the capacitance change, the electric field sensing electrode unit and the displacement reference electrode unit output an induced current signal and a displacement reference current signal, respectively. The induced electric signal and the displacement reference current signal are input into a signal detection circuit for conversion to obtain an induced voltage signal and a displacement reference voltage signal. While the induced voltage signal and the displacement reference voltage signal are compared and output to obtain the electric field strength of the electric field to be measured, the displacement reference voltage signal is input into a closed-loop feedback circuit. The closed-loop feedback circuit adjusts the excitation voltage according to the input displacement reference voltage signal, thereby modulating the excitation applied to the driving structure unit of the wafer-level packaged electric field sensor, so that the sensitivity of the output of the wafer-level packaged electric field sensor is constant, the sensitivity stability is maintained, and the common mode error is eliminated.

[0109] According to an embodiment of the present disclosure, a wafer-level packaged electric field sensor is placed in an electric field to be measured, and an excitation is applied to a 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-tooth structure in the movable structure unit, the displacement reference electrode unit generates and outputs a displacement reference electrical signal according to the capacitance change between the second comb-tooth structure and the comb-tooth structure of the displacement reference electrode unit. The displacement reference electrical signal is input into a closed-loop feedback circuit. Based on the displacement reference electrical signal, the closed-loop feedback circuit adjusts the voltage of the excitation to obtain a wafer-level packaged electric field sensor with constant sensitivity. In response to the vibration of the first comb-tooth 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. The induced electric signal and the displacement reference electric signal are compared and outputted to obtain the electric field strength of the electric field to be measured, thereby realizing accurate measurement of the electric field strength of the electric field to be measured, and by adjusting the magnitude of the excitation using a closed-loop feedback circuit according to the displacement reference electric signal, the wafer-level packaged electric field sensor can be controlled to measure the electric field strength of the electric field to be measured while keeping the output sensitivity constant, thereby maintaining the stability of the output sensitivity of the wafer-level packaged electric field sensor, and combining the output differential signal to eliminate the common mode error, and further, in conjunction with the selection of the resonator array of the movable structural unit inside the wafer-level packaged electric field sensor, the sensitivity of the wafer-level packaged electric field sensor can be adjusted to utilize the wafer-level packaged electric field sensor to measure the electric field to be measured with different degrees of accuracy.

[0110] Figure 7 The flowchart of the method for preparing the wafer-level packaged electric field sensor according to the embodiment of the present disclosure is schematically shown.

[0111] like Figure 7As shown, the method for preparing a wafer-level packaged electric field sensor may include operations S710 to S750.

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

[0113] According to an embodiment of the present disclosure, an electric field enhancement structure may be provided in the groove.

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

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

[0116] In operation S730, etching is performed on the second silicon-on-insulator device layer by using a photolithography and 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 used as a substrate, and etching is performed on the device layer of the substrate using a photolithography and etching process, thereby obtaining a substrate connected with a sensitive structure.

[0118] In operation S740, a silicon oxide layer in the substrate connected to the sensitive structure is etched by a wet etching process to release the sensitive structure in the substrate so that the sensitive structure can vibrate freely.

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

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

[0121] According to the embodiments of the present disclosure, the bonding method is not limited to anodic bonding or silicon-silicon bonding, but may also include other bonding methods, which are not limited thereto.

[0122] According to the embodiments of the present disclosure, a groove is etched in a device layer of silicon on a first insulator by utilizing a photolithography and etching process to obtain a cover plate containing the groove, a getter is deposited on the inner surface of the groove by utilizing an evaporation process to obtain a wafer-level packaging cover plate, a photolithography and etching process is used to perform etching on the device layer of silicon on a second insulator to obtain a substrate connected with a sensitive structure, a wet etching process is used to etch the silicon oxide layer in the substrate connected with the sensitive structure to release the sensitive structure in the substrate, the wafer-level packaging cover plate is aligned with the substrate and then an anodic bonding or silicon-silicon bonding operation is performed to obtain a wafer-level packaging electric field sensor, thereby realizing the preparation of the wafer-level packaging electric field sensor, improving the preparation success rate, and reducing the difficulty of preparing the sensor. The wafer-level packaging electric field sensor prepared by the above method can be combined with a closed-loop feedback circuit to realize sensitivity self-compensation measurement to maintain a stable sensitivity.

[0123] Figure 8 A schematic diagram of a method for preparing a wafer-level packaged electric field sensor according to an embodiment of the present disclosure is schematically shown.

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

[0125] According to an embodiment of the present disclosure, the electric field sensor may include a wafer-level packaged electric field sensor manufactured by the manufacturing method described above.

[0126] According to an embodiment of the present disclosure, the above-mentioned wafer-level packaged electric field sensor may also be prepared by another preparation method, which may include the following operations.

[0127] According to an embodiment of the present disclosure, two first grooves are etched on a silicon wafer using a photolithography and 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 using glass reflow technology, and the redundant glass layers and silicon layers above and below are removed by grinding and polishing, so that the glass medium in the first groove passes 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 using a photolithography and etching process, and the electric field enhancement structure is thinned by the photolithography and etching process to obtain a cover plate connected with the electric field enhancement structure.

[0130] According to an embodiment of the present disclosure, a getter 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, etching is performed on the device layer of silicon-on-insulator using a photolithography and etching process to obtain a substrate connected with a sensitive structure.

[0132] According to an embodiment of the present disclosure, a silicon oxide layer in a substrate connected to a sensitive structure is etched using a wet etching process to release the sensitive structure in the substrate so that the sensitive structure can vibrate freely.

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

[0134] According to the embodiments of the present disclosure, the bonding method is not limited to anodic bonding or silicon-silicon bonding, but may also include other bonding methods, which are not limited thereto.

[0135] According to the embodiments of the present disclosure, a wafer-level packaged electric field sensor can be prepared by the above-mentioned preparation method, and the concentration effect of the electric field can be enhanced by combining the electric field enhancement structure to improve the sensitivity. The applied excitation is adjusted according to the displacement reference electrical signal in conjunction with an external closed-loop feedback circuit to stabilize the output sensitivity of the sensor and eliminate the common mode error based on the output differential signal.

[0136] According to an embodiment of the present disclosure, the electric field sensor may include a wafer-level packaged electric field sensor manufactured by the manufacturing method described above.

[0137] Fig. 9 A schematic diagram of a method for preparing a wafer-level packaged electric field sensor according to another embodiment of the present disclosure is schematically shown.

[0138] like Fig. 9 As shown, Fig. 9The present invention shows a method for preparing a wafer-level packaged electric field sensor, wherein the white layer 901 represents a silicon layer, the shadow layer 902 represents a getter, the shadow layer 903 represents silicon dioxide, and the shadow layer 904 represents glass. First, two first grooves are etched on a silicon wafer using a photolithography 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 using a glass reflow technology, and excess glass layers and silicon layers above and below are removed by grinding and polishing, so that the glass medium in the first grooves penetrates the cover plate (b). Two second grooves and an electric field enhancement structure are etched on the silicon wafer using a photolithography process, and the electric field enhancement structure is etched by a photolithography process. The wafer-level packaging cover plate (d) is obtained by thinning the wafer-level packaging cover plate (a) to (d), and a getter is deposited on the inner surface of the two second grooves and the outer surface of the electric field enhancement structure by an evaporation process to obtain a wafer-level packaging cover plate (d). While preparing the wafer-level packaging cover plates (a) to (d), a photolithography etching process can be used to etch the device layer of silicon on insulator to obtain a substrate connected to a sensitive structure (e). Then, a wet etching process is used to etch the silicon oxide layer in the substrate connected to the sensitive structure to release the sensitive structure in the substrate (f). Finally, the wafer-level packaging cover plate and the substrate are aligned and anodized or silicon-silicon bonded to obtain a wafer-level packaging electric field sensor (g).

[0139] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations and / or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0140] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present disclosure in detail. 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 substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A wafer-level packaged electric field sensor, comprising: A substrate, used to support the sensitive structure and the wafer-level packaging cover plate, wherein the surface of the substrate is provided with anchor points; A sensitive structure is fixed above the substrate through an anchor point, the sensitive structure includes an electric field sensing electrode unit and a displacement reference electrode unit, and is used for the electric field sensing electrode unit to generate an induced electric signal and the displacement reference electrode unit to generate a displacement reference electric signal when an excitation is applied to the sensitive structure, so as to compensate for the common mode error of the wafer-level package electric field sensor according to the induced electric signal and the displacement reference electric signal, thereby improving the output sensitivity of the wafer-level package electric field sensor; A wafer-level packaging cover plate is arranged above the sensitive structure and is used to form a closed chamber together with the substrate so that the sensitive structure in the closed chamber is in a vacuum working environment, so as to improve the quality factor of the wafer-level packaging electric field sensor.

2. The sensor according to claim 1, characterized in that The sensitive structure also includes 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 the sensing electric signal and the displacement reference electric signal respectively.

3. The sensor according to claim 2, characterized in that The movable structure unit includes a first comb tooth structure and a second comb tooth structure, the electric field sensing electrode unit generates an induced electric signal, and the displacement reference electrode unit generates a displacement reference electric signal, including: The first comb-tooth structure is disposed on one side of the electric field sensing electrode unit and is arranged in a differentially staggered manner with the comb-tooth structure of the electric field sensing electrode unit, and is used for generating and outputting the induced electrical signal by the electric field sensing electrode unit based on the charge induction principle in response to the vibration of the first comb-tooth structure; The second comb tooth structure is arranged on one side of the displacement reference electrode unit and is arranged in an staggered manner with the comb tooth structure of the displacement reference electrode unit. It is used to change the capacitance between the second comb tooth structure and the comb tooth structure of the displacement reference electrode unit in response to the vibration of the second comb tooth structure. According to the capacitance change, the displacement reference electrode unit generates and outputs the displacement reference electrical signal.

4. The sensor according to claim 1, characterized in that The wafer-level packaging cover plate comprises a cover plate, an insulating dielectric layer and an electric field enhancement structure; The lower surface of the cover plate is fixed above the substrate through the insulating dielectric layer, and is used to form a closed chamber with the insulating dielectric 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. 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 strength acting on the sensitive structure.

5. The sensor according to claim 1, characterized in that The movable structural unit also includes an elastic beam, which is arranged on both sides of the first comb tooth structure and the second comb tooth structure for supporting the first comb tooth structure and the second comb tooth structure. The elastic beam is one of a straight beam, a folded beam and a curved beam or a combination thereof.

6. The sensor according to claim 1, characterized in that The resonator includes the elastic beam and the first comb tooth structure and / or the second comb tooth structure, and the movable structure unit is a single resonator structure or a multi-resonator coupling structure. The single resonator structure includes one resonator, which is used to vibrate the first comb tooth structure and the second comb tooth structure with the same amplitude in response to the driving of the driving structure unit, so that the output sensitivity of the wafer-level package electric field sensor is a predetermined value; The multi-resonator coupling structure includes a plurality of resonators, which are used to vibrate the first comb tooth structure and the second comb tooth 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 package electric field sensor.

7. An electric field detection method using the wafer-level packaged electric field sensor according to any one of claims 1 to 6, comprising: Placing the wafer-level package electric field sensor in the electric field to be measured; Applying excitation to the driving structure unit of the wafer-level packaged electric field sensor to vibrate the movable structure unit; In response to the vibration of the second comb-tooth structure in the movable structure unit, the displacement reference electrode unit generates and outputs a displacement reference electrical signal according to the capacitance change between the second comb-tooth structure and the comb-tooth structure of the displacement reference electrode unit; Inputting the displacement reference electrical signal into a closed-loop feedback circuit; Based on the displacement reference electrical signal, the closed-loop feedback circuit adjusts the voltage of the excitation to obtain the wafer-level package electric field sensor with constant sensitivity; In response to the vibration of the first comb structure of the wafer-level package electric field sensor with constant sensitivity, the electric field sensing electrode unit generates and outputs an induced electric signal based on the charge induction principle; The induced electric signal and the displacement reference electric signal are compared and output to obtain the electric field strength of the electric field to be measured.

8. A method for preparing a wafer-level packaged electric field sensor, comprising: Etching a groove in the device layer of silicon on the first insulator by using a photolithography and 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 on the device layer of the second silicon-on-insulator by using a photolithography and etching process to obtain a substrate connected with a sensitive structure, wherein the second silicon-on-insulator is the substrate; Etching the silicon oxide layer in the substrate connected with the sensitive structure by a wet etching process to release the sensitive structure in the substrate so as to facilitate free vibration of the sensitive structure; After aligning the wafer-level packaging cover plate and the substrate, an anodic bonding or silicon-silicon bonding operation is performed to obtain the wafer-level packaging electric field sensor.

9. An electric field sensor, comprising: The wafer-level packaged electric field sensor according to any one of claims 1 to 6 or the wafer-level packaged electric field sensor obtained by the preparation method according to claim 8.

10. The electric field sensor according to claim 9, characterized in that: The electric field sensor also includes a two-dimensional or three-dimensional electric field sensor composed of a plurality of electric field sensitive structures, which is used to measure a two-dimensional or three-dimensional electric field or voltage.

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