Electric field sensor with field enhancement packaging cover plate and preparation method thereof

Abstract

The invention provides an electric field sensor with a field enhancement packaging cover plate and a preparation method of the electric field sensor, and relates to the technical field of electric field sensor packaging. The electric field sensor comprises a conductor layer (1) located on the top layer, and a field enhancement conductive structure (2) and an isolation layer (3) which are arranged on the lower surface of the conductor layer (1). The device layer (4), the insulating layer (5) and the substrate layer (6) are sequentially arranged on the lower surface of the isolating layer (3); a shielding electrode (7) capable of vibrating relative to the device layer (4) and an induction electrode (8) fixed relative to the device layer (4) are arranged in a specified electric field induction area in the device layer (4), and a first isolation groove (9) is reserved between the shielding electrode (7) and the induction electrode (8); a first cavity (16) is formed in the position, corresponding to the electric field induction area, of the insulating layer (5); a second cavity (13) is formed in the position, corresponding to the electric field induction area, of the isolation layer (3), and the field enhancement conductive structure (2) is contained in the second cavity (13).

Description

Technical Field

[0001] This application relates to the field of electric field sensor packaging technology, and more specifically, to an electric field sensor with a field-enhancing packaging cover and a method for fabricating the same. Background Technology

[0002] An electric field sensor is a type of sensor with good resistance to electromagnetic interference and fast response speed. It is used to detect the external electric field, and the detection results can be used to monitor the impact of solar activity on the near-Earth atmospheric electric field, urban environmental pollution, and to forecast phenomena such as thunderstorms and earthquakes.

[0003] Currently, electric field sensors suffer from drawbacks such as large size, high power consumption, high price, and difficulty in integration, failing to adequately meet the demands of aerospace, new power systems, and other fields for lightweight, low-power sensors. While electric field sensors fabricated using wafer-level packaging reduce size, they are prone to experiencing a decrease in sensitivity. Summary of the Invention

[0004] In view of the above problems, this application provides an electric field sensor with a field-enhancing encapsulation cover and a method for fabricating the same.

[0005] This application provides an electric field sensor with a field-enhanced encapsulation cover, comprising: a conductor layer at the top layer, and a field-enhancing conductive structure and an isolation layer respectively disposed on the lower surface of the conductor layer; the electric field sensor further comprises a device layer, an insulating layer, and a substrate layer sequentially disposed on the lower surface of the isolation layer; a designated electric field sensing region in the device layer is provided with a shielding electrode that is vibrating relative to the device layer and a sensing electrode that is fixed relative to the device layer, and a first isolation groove is provided between the shielding electrode and the sensing electrode for electrical isolation between the shielding electrode and the sensing electrode; a first cavity is formed on the insulating layer at a position corresponding to the electric field sensing region for providing vibration space for the shielding electrode; a second cavity is formed on the isolation layer at a position corresponding to the electric field sensing region for accommodating the field-enhancing conductive structure; the conductor layer is used to receive an external electric field, the field-enhancing conductive structure is used to enhance the external electric field, and the electric field sensor is used to drive the shielding electrode to vibrate through the enhanced external electric field to form a shield for the sensing electrode, and to measure the electric field strength of the external electric field by monitoring the change in induced charge of the sensing electrode.

[0006] According to an embodiment of this application, multiple electrode pads are symmetrically arranged on both sides of the electric field sensing region. Each electrode pad is electrically connected to a shielding electrode and a sensing electrode, respectively, for extracting the vibration signal generated by the shielding electrode due to vibration and the change in induced charge of the sensing electrode. Among the multiple electrode pads, a second isolation groove is left between two adjacent electrode pads, and the second isolation groove is used to electrically isolate the two adjacent electrode pads.

[0007] According to an embodiment of this application, the field-enhanced packaging cover further includes: a plurality of first lead holes that vertically penetrate the conductor layer and have the same number as the electrode pads, the plurality of first lead holes being symmetrically distributed along the central axis of the electric field sensing region; and a plurality of second lead holes that vertically penetrate the isolation layer, the plurality of second lead holes being opened on the isolation layer at positions corresponding to the plurality of first lead holes.

[0008] According to an embodiment of this application, the area exposed on the surface of each second lead hole falls on the upper surface of an electrode pad, and the second isolation groove outside any electrode pad is located outside the area exposed on the surface of the corresponding second lead hole.

[0009] According to an embodiment of this application, the diameter of any second lead hole is not less than the diameter of the corresponding first lead hole, and the central axis of any second lead hole, the central axis of the first lead hole corresponding to the second lead hole, and the central axis of the electrode pad corresponding to the second lead hole are coaxial.

[0010] According to an embodiment of this application, the field enhancement package cover further includes: a metal electrode disposed in the area of ​​each second lead hole exposed on the surface of the device layer, the metal electrode being electrically connected to the conductor layer.

[0011] According to an embodiment of this application, the field-enhanced conductive structure includes: an inner layer structure, which is a conductor extending downward from a portion of the lower surface of a conductive silicon substrate; and an outer layer structure, which covers the outer surface of the inner layer structure; wherein the inner layer structure is used to conduct an external electric field to the outer layer structure, and the outer layer structure is used to enhance the conducted external electric field.

[0012] According to embodiments of this application, the conductor layer and the isolation layer are integrated via an anodic bonding process; the isolation layer and the device layer are integrated via an anodic bonding process.

[0013] Another aspect of this application provides a method for fabricating an electric field sensor with a field-enhancing encapsulation cover as described above, comprising: providing a conductor layer, an isolation layer, and a substrate layer; anodicly bonding the lower surface of the conductor layer to the isolation layer and forming a field-enhancing conductive structure on the lower surface of the conductor layer; forming a second cavity on the isolation layer and accommodating the field-enhancing conductive structure therein to obtain a field-enhancing encapsulation cover; sequentially forming an insulating layer and a device layer from bottom to top on the substrate layer; forming a vibrating shielding electrode relative to the device layer and a fixed sensing electrode relative to the device layer in a specified electric field sensing region in the device layer, and forming a first isolation groove between the shielding electrode and the sensing electrode; forming a first cavity on the insulating layer corresponding to the position of the electric field sensing region to obtain a sensitive structure; anodicly bonding the field-enhancing encapsulation cover and the sensitive structure so that the position of the second cavity corresponds to the position of the electric field sensing region to obtain an electric field sensor.

[0014] According to an embodiment of this application, an electric field sensor is obtained by anodic bonding of a field enhancement package cover and a sensitive structure. The process includes: forming a plurality of symmetrically arranged electrode pads on both sides of the electric field sensing region of the sensitive structure, and forming a second isolation groove between two adjacent electrode pads; forming a plurality of first lead holes perpendicularly penetrating the conductor layer and having the same number as the electrode pads, and a plurality of second lead holes perpendicularly penetrating the isolation layer on the field enhancement package cover; anodic bonding of the sensitive structure with the plurality of electrode pads to the field enhancement package cover with the plurality of first lead holes and the plurality of second lead holes, such that the central axis of any second lead hole, the central axis of the first lead hole corresponding to the second lead hole, and the central axis of the electrode pad corresponding to the second lead hole are coaxial, thus obtaining the electric field sensor.

[0015] The electric field sensor with a field-enhancing encapsulation cover and its fabrication method provided in this application can achieve the following beneficial effects:

[0016] (1) By setting a field-enhancing conductive structure on the lower surface of the conductor layer and opening a second cavity on the isolation layer to accommodate the field-enhancing conductive structure, the field-enhancing conductive structure can effectively enhance the external electric field received by the conductor layer without obstruction. The enhanced external electric field can drive the shielding electrode to vibrate more efficiently, amplify the change in induced charge of the sensing electrode, realize the accurate capture of the external electric field, and improve the sensitivity of the electric field sensor.

[0017] (2) By changing the thickness of the isolation layer, the distance between the device layer and the conductor layer can be flexibly changed, so as to achieve precise control of the enhancement of the external electric field, adapt to the detection requirements of external electric fields of different intensities, and effectively broaden the electric field detection range of the electric field sensor.

[0018] (3) Through secondary anodic bonding, electrical connection with the field enhancement packaging cover is achieved, which makes the process compatibility of the sensitive structure in the electric field sensor good, and the packaging cost of the electric field sensor is low and the packaging efficiency is high. Attached Figure Description

[0019] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0020] Figure 1 This schematically illustrates a structural diagram of an electric field sensor with a field-enhancing encapsulation cover according to an embodiment of this application;

[0021] Figure 2 The diagram illustrates the sensing pattern of an electric field sensor with a field-enhancing encapsulation cover according to an embodiment of this application.

[0022] Figure 3 A cross-sectional view of a sensitive structure according to an embodiment of this application is schematically shown;

[0023] Figure 4 A schematic cross-sectional view of a field-enhanced encapsulation cover according to an embodiment of this application is shown;

[0024] Figure 5 A schematic cross-sectional view of a conductor layer according to an embodiment of this application is shown;

[0025] Figure 6 A schematic cross-sectional view of the isolation layer and field-enhanced conductive structure according to an embodiment of this application is shown;

[0026] Figure 7 A schematic diagram illustrating the structure of the second cavity according to an embodiment of this application is shown. Figure 7 (a) schematically illustrates the structure of the insulating layer before treatment according to an embodiment of this application; Figure 7 (b) schematically illustrates a structural diagram of the insulation layer after treatment according to an embodiment of this application;

[0027] Figure 8 A flowchart illustrating a method for fabricating an electric field sensor with a field-enhancing encapsulation cover according to an embodiment of this application is shown.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1-Conductor layer; 2-Field-enhancing conductive structure; 3-Isolation layer; 4-Device layer; 5-Insulating layer; 6-Substrate layer; 7-Shielding electrode; 8-Induction electrode; 9-First isolation trench; 10-Gap; 11-First lead hole; 12-Second lead hole; 13-Second cavity; 14-Electrode pad; 15-Metal electrode; 16-First cavity; 17-Second isolation trench. Detailed Implementation

[0030] The embodiments of this application will now 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 this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

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

[0033] Figure 1 This schematically illustrates a structural diagram of an electric field sensor with a field-enhancing encapsulation cover according to an embodiment of this application; Figure 2 The diagram illustrates the sensing pattern of an electric field sensor with a field-enhancing encapsulation cover according to an embodiment of this application.

[0034] like Figure 1 and Figure 2 As shown, in the electric field sensor with a field enhancement encapsulation cover in this embodiment, the field enhancement encapsulation cover includes a conductor layer 1 located at the top layer, and a field enhancement conductive structure 2 and an isolation layer 3 respectively disposed on the lower surface of the conductor layer 1; the electric field sensor also includes a device layer 4, an insulating layer 5 and a substrate layer 6 disposed sequentially on the lower surface of the isolation layer 3;

[0035] The electric field sensing area specified in the device layer 4 is provided with a shielding electrode 7 that is vibrating relative to the device layer 4 and a sensing electrode 8 that is fixed relative to the device layer 4. A first isolation groove 9 is left between the shielding electrode 7 and the sensing electrode 8 for electrical isolation between the shielding electrode 7 and the sensing electrode 8.

[0036] A first cavity 16 is formed on the insulating layer 5 at the position corresponding to the electric field sensing area, which is used to provide vibration space for the shielding electrode 7; a second cavity 13 is formed on the isolation layer 3 at the position corresponding to the electric field sensing area, which is used to accommodate the field-enhancing conductive structure 2.

[0037] Conductor layer 1 is used to receive external electric field, field-enhancing conductive structure 2 is used to enhance external electric field, electric field sensor is used to drive shielding electrode 7 to vibrate through enhanced external electric field to form shielding for sensing electrode 8, and electric field strength of external electric field is measured by monitoring the change of induced charge on sensing electrode 8.

[0038] For example, the field-enhancing conductive structure 2 can be a columnar structure and is disposed perpendicular to the conductor layer 1.

[0039] For example, when an external electric field is applied, the electric field sensor can drive the shielding electrode 7 to generate periodic vibrations, forming a periodic shield on the sensing electrode 8, causing changes in the surface charge of the sensing electrode 8, and thus completing the measurement of the external electric field.

[0040] The electric field sensor with a field-enhancing encapsulation cover according to the embodiments of this application integrates a field-enhancing conductive structure through the field-enhancing encapsulation cover, which can enhance the external electric field and improve the sensitivity and response efficiency of electric field sensing; the structural design of the shielding electrode and the sensing electrode realizes dynamic shielding of the sensing electrode; and the external electric field strength is accurately measured by relying on the change of induced charge of the sensing electrode, thereby improving the accuracy and reliability of external electric field strength measurement.

[0041] Figure 3 A cross-sectional view of a sensitive structure according to an embodiment of this application is schematically shown.

[0042] like Figure 3 As shown, the device layer 4 also includes: a plurality of electrode pads 14 symmetrically arranged on both sides of the electric field sensing region, each electrode pad 14 being electrically connected to the shielding electrode 7 and the sensing electrode 8 respectively, for extracting the vibration signal generated by the vibration of the shielding electrode 7 and the change in induced charge of the sensing electrode 8; among the plurality of electrode pads 14, a second isolation groove 17 is left between two adjacent electrode pads 14, the second isolation groove 17 being used to electrically isolate two adjacent electrode pads 14.

[0043] For example, device layer 4 can be based on SOI (silicon-on-insulator) top silicon, insulating layer 5 can be SOI buried oxide layer, and substrate layer 6 can be SOI bottom silicon.

[0044] The electric field sensor with a field-enhancing package cover according to the embodiments of this application can extract the vibration signal of the shielding electrode 7 and the induced charge change of the sensing electrode 8 through the symmetrically arranged electrode pads 14, so as to realize the independent transmission of the two signals, avoid signal crosstalk, and improve the accuracy of electric field strength detection. The symmetrical layout makes the electrode lead-out structure regular, which is compatible with the micro-electro-mechanical systems (MEMS) microfabrication process, simplifies the packaging and testing process, and improves the integration and working stability of the device.

[0045] Figure 4 A schematic cross-sectional view of a field-enhanced encapsulation cover according to an embodiment of this application is shown; Figure 5 A schematic cross-sectional view of a conductor layer according to an embodiment of this application is shown.

[0046] like Figure 4 and Figure 5 As shown, the field enhancement package cover also includes: a plurality of first lead holes 11 that penetrate the conductor layer 1 vertically and are the same number as the electrode pads 14, the plurality of first lead holes 11 being symmetrically distributed along the central axis of the electric field sensing region; a plurality of second lead holes 12 that penetrate the isolation layer 3 vertically, and the plurality of second lead holes 12 being opened on the isolation layer 3 at positions corresponding to the plurality of first lead holes 11.

[0047] In the embodiments of this application, the diameter of any second lead hole 12 is not less than the diameter of the corresponding first lead hole 11, and the central axis of any second lead hole 12, the central axis of the first lead hole 11 corresponding to the second lead hole 12, and the central axis of the electrode pad 14 corresponding to the second lead hole 12 are coaxial.

[0048] For example, the diameter of the first lead hole 11 can be the same as the diameter of the second lead hole 12.

[0049] The electric field sensor with a field-enhancing encapsulation cover according to the embodiments of this application avoids poor contact and open circuit risk caused by misalignment by coaxially setting lead holes (first lead hole and second lead hole) and electrode pads, thereby improving the reliability of electrical connection; the diameter of the second lead hole is not less than the diameter of the corresponding first lead hole, which can reduce stress concentration and prevent interlayer cracking.

[0050] In the embodiments of this application, the area of ​​each second lead hole 12 exposed on the surface of the device layer 4 falls on the upper surface of an electrode pad 14, and the second isolation groove 17 outside any electrode pad 14 is located outside the area of ​​the corresponding second lead hole 12 exposed on the surface of the device layer 4.

[0051] In embodiments of this application, the field enhancement package cover further includes a metal electrode 15 disposed in the area of ​​each second lead hole 12 exposed on the surface of the device layer 4, the metal electrode 15 being electrically connected to the conductor layer 1.

[0052] Figure 6 A schematic cross-sectional view of the isolation layer and field-enhanced conductive structure according to an embodiment of this application is shown.

[0053] like Figure 6 As shown, the field-enhancing conductive structure 2 includes: an inner layer structure, which is a conductor extending downward from a portion of the lower surface of the conductor silicon 1; and an outer layer structure, which covers the outer surface of the inner layer structure; wherein, the inner layer structure is used to conduct an external electric field to the outer layer structure, and the outer layer structure is used to enhance the conducted external electric field.

[0054] The electric field sensor with a field-enhancing encapsulation cover according to the embodiments of this application achieves efficient conduction of the external electric field through the encapsulation design of the inner and outer layer structures, improves the enhancement efficiency and uniformity of the external electric field, and enhances the sensing sensitivity of the electric field sensor to weak electric fields.

[0055] In the embodiments of this application, the conductor layer 1 and the isolation layer 3 are integrated by anodizing bonding process; the isolation layer 3 and the device layer 4 are integrated by anodizing bonding process.

[0056] Heterogeneous integration of conductor layer 1, isolation layer 3 and device layer 4 is achieved through anodic bonding.

[0057] Figure 7 A schematic diagram illustrating the structure of the second cavity according to an embodiment of this application is shown. Figure 7 (a) schematically illustrates the structure of the insulating layer before treatment according to an embodiment of this application; Figure 7 (b) schematically illustrates the structure after the insulation layer has been treated according to an embodiment of this application.

[0058] like Figure 7 As shown in (a), a shielding electrode 7, an induction electrode 8, and a plurality of electrode pads 14 are prepared on an insulating layer 5, and a specified electric field induction area is reserved between the plurality of electrode pads 14.

[0059] like Figure 7 As shown in (b), the area corresponding to the electric field sensing area is removed from the insulating layer 5, so that there is a gap 10 between the insulating layer 5 and the shielding electrode 7 and the sensing electrode 8. The gap 10 and the first isolation groove 9 together form the second cavity 16.

[0060] Based on the above-mentioned electric field sensor with a field-enhancing encapsulation cover, this application also provides a method for fabricating an electric field sensor with a field-enhancing encapsulation cover, which is described below in conjunction with... Figure 8 This method will be described in detail.

[0061] Figure 8 A flowchart illustrating a method for fabricating an electric field sensor with a field-enhancing encapsulation cover according to an embodiment of this application is shown.

[0062] like Figure 8 As shown, the method for fabricating an electric field sensor with a field-enhancing encapsulation cover in this embodiment includes steps S110 to S150.

[0063] In step S110, a conductor layer 1, an isolation layer 3, and a substrate layer 6 are provided.

[0064] For example, the isolation layer 3 can be glass, and the glass material can be BF33 glass (special borosilicate glass) or Pyrex glass, which are suitable for anodic bonding processes, so that it can achieve high-strength and high-hermeticity bonding and encapsulation with the conductor layer 1.

[0065] In step S120A, the lower surface of the conductor layer 1 is anodicly bonded to the isolation layer 3, and a field-enhanced conductive structure 2 is formed on the lower surface of the conductor layer 1.

[0066] Heterogeneous integration of conductor layer 1 and isolation layer 3 can be achieved through anodic bonding.

[0067] For example, the field-enhanced conductive structure 2 includes an inner layer structure and an outer layer structure. The outer layer structure can be obtained by hydrofluoric acid wet etching or laser etching, and the material of the outer layer structure can be a metal material compatible with semiconductor processes, such as Cr, Cu, Al, Au, Ti, or Ta. The outer layer structure is electrically connected to the conductor layer 1.

[0068] In step S130A, a second cavity 13 is formed on the isolation layer 3, and the second cavity 13 is used to accommodate the field-enhancing conductive structure 2 to obtain a field-enhancing encapsulation cover.

[0069] For example, a second cavity 13 can be formed by etching on the isolation layer 3.

[0070] In step S120B, an insulating layer 5 and a device layer 4 are formed sequentially from bottom to top on the substrate layer 6.

[0071] In step S130B, a shielding electrode 7 that is vibrating relative to the device layer 4 and a sensing electrode 8 that is fixed relative to the device layer 4 are formed in the electric field sensing region specified in the device layer 4, and a first isolation groove 9 is formed between the shielding electrode 7 and the sensing electrode 8.

[0072] For example, shielding electrode 7, sensing electrode 8 and first isolation trench 9 can be fabricated on the surface of device layer 4 by photolithography and deep silicon etching processes to achieve electrical isolation between shielding electrode 7 and sensing electrode 8.

[0073] In step S140B, a first cavity 16 corresponding to the position of the electric field sensing region is formed on the insulating layer 5 to obtain the sensitive structure.

[0074] For example, the sensitive structure can be fabricated using SOI wafers, forming a pair of sensing electrodes 8 and shielding electrodes 7.

[0075] For example, the insulating layer 5 can be treated by gaseous hydrogen fluoride corrosion or hydrofluoric acid wet corrosion combined with carbon dioxide critical point drying to form a first cavity 16 corresponding to the position of the electric field induction region.

[0076] In step S150, the field enhancement encapsulation cover and the sensitive structure are anodicly bonded so that the position of the second cavity 13 corresponds to the position of the electric field sensing area, thus obtaining the electric field sensor.

[0077] For example, by changing the thickness of the isolation layer 3, the distance between the sensing electrode 8 and the field enhancement packaging cover in the sensitive structure can be flexibly changed.

[0078] The bonded electric field sensor can establish a stable electric field enhancement sensing channel.

[0079] In this embodiment, an electric field sensor is obtained by anodic bonding of a field enhancement package cover and a sensitive structure. This includes: forming a plurality of symmetrically arranged electrode pads 14 on both sides of the electric field sensing region of the sensitive structure, and forming a second isolation groove 17 between two adjacent electrode pads 14; forming a plurality of first lead holes 11 perpendicularly penetrating the conductor layer 1 and having the same number as the electrode pads 14 on the field enhancement package cover, and a plurality of second lead holes 12 perpendicularly penetrating the isolation layer 3; anodic bonding of the sensitive structure with the plurality of electrode pads 14 to the field enhancement package cover with the plurality of first lead holes 11 and the plurality of second lead holes 12, such that the central axis of any second lead hole 12, the central axis of the first lead hole 11 corresponding to the second lead hole 12, and the central axis of the electrode pad 14 corresponding to the second lead hole 12 are coaxial, thus obtaining the electric field sensor.

[0080] For example, multiple first lead holes 11 can be etched on the conductor layer 1 by wet etching, laser etching, or photolithography patterning-assisted deep silicon etching. Patterning assistance includes, but is not limited to, using hard mask protection. Multiple second lead holes 12 can be etched on the isolation layer 3 by laser etching or hydrofluoric acid wet etching, such that the diameter of each second lead hole 12 is not less than the diameter of the first lead hole 11.

[0081] For example, the central axis of any second lead hole 12, the central axis of the first lead hole 11 corresponding to the second lead hole 12, and the central axis of the electrode pad 14 corresponding to the second lead hole 12 can be made coaxial by using an auxiliary microscope or wafer alignment equipment.

[0082] In embodiments of this application, a metal electrode 15 is grown at the bottom of each second lead hole 12.

[0083] For example, a metal electrode 15 can be grown at the bottom of the second lead hole 12 using thermal evaporation or electron beam evaporation processes. The metal electrode 15 can be made of a material with good conductivity, such as gold, aluminum, or copper.

[0084] For example, a blind trench can be etched in the insulating layer 3, and the depth of the blind trench is not less than the thickness of the insulating layer 3; a cylindrical boss can be retained in the middle of the blind trench, and the height of the boss is less than the thickness of the insulating layer 3. The material of the boss can be the same as that of the insulating layer 3, and the boss can be formed in the middle of the blind trench by laser processing or wet etching.

[0085] For example, the metal electrode 15 can be covered on the boss to achieve electrical communication with the conductor layer 1. The metal electrode 15 can be coated on the boss by evaporation or magnetron sputtering.

[0086] In summary, the embodiments of this application provide an electric field sensor with a field-enhancing encapsulation cover and a method for fabricating the same, which has the following beneficial effects:

[0087] (1) By setting a field-enhancing conductive structure on the lower surface of the conductor layer and opening a second cavity on the isolation layer to accommodate the field-enhancing conductive structure, the field-enhancing conductive structure can effectively enhance the external electric field received by the conductor layer without obstruction. The enhanced external electric field can drive the shielding electrode to vibrate more efficiently, amplify the change in induced charge of the sensing electrode, realize the accurate capture of the external electric field, and improve the sensitivity of the electric field sensor.

[0088] (2) By changing the thickness of the isolation layer, the distance between the device layer and the conductor layer can be flexibly changed, so as to achieve precise control of the enhancement of the external electric field, adapt to the detection requirements of external electric fields of different intensities, and effectively broaden the electric field detection range of the electric field sensor.

[0089] (3) Through secondary anodic bonding, electrical connection with the field enhancement packaging cover is achieved, which makes the process compatibility of the sensitive structure in the electric field sensor good, and the packaging cost of the electric field sensor is low and the packaging efficiency is high.

[0090] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined or combined in various ways without departing from the spirit and teachings of this application. All such combinations or combinations fall within the scope of this application.

[0091] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Without departing from the scope of this application, those skilled in the art can make various substitutions and modifications, all of which should fall within the scope of this application.

Claims

1. An electric field sensor with a field-enhancing encapsulation cover, characterized in that, include: The field-enhanced encapsulation cover includes a conductor layer (1) located on the top layer, and a field-enhanced conductive structure (2) and an isolation layer (3) respectively disposed on the lower surface of the conductor layer (1). The electric field sensor also includes a device layer (4), an insulating layer (5) and a substrate layer (6) sequentially disposed on the lower surface of the isolation layer (3); The electric field sensing region specified in the device layer (4) is provided with a shielding electrode (7) that is vibrating relative to the device layer (4) and a sensing electrode (8) that is fixed relative to the device layer (4). A first isolation groove (9) is left between the shielding electrode (7) and the sensing electrode (8) for electrically isolating the shielding electrode (7) and the sensing electrode (8). A first cavity (16) is provided on the insulating layer (5) at the position corresponding to the electric field sensing area, for providing vibration space for the shielding electrode (7); A second cavity (13) is provided on the isolation layer (3) at the position corresponding to the electric field sensing region, for accommodating the field-enhancing conductive structure (2); The conductor layer (1) is used to receive an external electric field, the field-enhancing conductive structure (2) is used to enhance the external electric field, the electric field sensor is used to drive the shielding electrode (7) to vibrate through the enhanced external electric field to form a shield for the sensing electrode (8), and the electric field strength of the external electric field is measured by monitoring the change in induced charge of the sensing electrode (8).

2. The electric field sensor according to claim 1, characterized in that, The device layer (4) further includes: Multiple electrode pads (14) are symmetrically arranged on both sides of the electric field sensing area. Each electrode pad (14) is electrically connected to the shielding electrode (7) and the sensing electrode (8) respectively, and is used to extract the vibration signal generated by the shielding electrode (7) due to vibration and the change in induced charge of the sensing electrode (8). In the plurality of electrode pads (14), a second isolation groove (17) is provided between two adjacent electrode pads (14), the second isolation groove (17) is used to electrically isolate the two adjacent electrode pads (14).

3. The electric field sensor according to claim 2, characterized in that, The field-enhanced encapsulation cover also includes: A plurality of first lead holes (11) perpendicularly penetrate the conductor layer (1) and are the same number as the electrode pads (14), the plurality of first lead holes (11) being symmetrically distributed along the central axis of the electric field sensing region; Multiple second lead holes (12) are perpendicularly penetrating the isolation layer (3), and the multiple second lead holes (12) are opened on the isolation layer (3) at positions corresponding to the multiple first lead holes (11).

4. The electric field sensor according to claim 3, characterized in that, The area of ​​each second lead hole (12) exposed on the surface of the device layer (4) falls on the upper surface of one of the electrode pads (14), and the second isolation groove (17) outside any of the electrode pads (14) is located outside the area of ​​the corresponding second lead hole (12) exposed on the surface of the device layer (4).

5. The electric field sensor according to claim 3, characterized in that, The diameter of any second lead hole (12) is not less than the diameter of the corresponding first lead hole (11), and the central axis of any second lead hole (12), the central axis of the first lead hole (11) corresponding to the second lead hole (12), and the central axis of the electrode pad (14) corresponding to the second lead hole (12) are coaxial.

6. The electric field sensor according to claim 3, characterized in that, The field-enhanced encapsulation cover also includes: Each of the second lead holes (12) has a metal electrode (15) disposed in the area exposed on the surface of the device layer (4), and the metal electrode (15) is electrically connected to the conductor layer (1).

7. The electric field sensor according to claim 1, characterized in that, The field-enhanced conductive structure (2) includes: The inner layer structure is a conductor extending downward from a portion of the lower surface of the conductor silicon (1); An outer layer structure, which covers the outer surface of the inner layer structure; The inner layer structure is used to conduct the external electric field to the outer layer structure, and the outer layer structure is used to enhance the conducted external electric field.

8. The electric field sensor according to claim 1, characterized in that, The conductor layer (1) and the isolation layer (3) are integrated by anodizing; the isolation layer (3) and the device layer (4) are integrated by anodizing.

9. A method for fabricating an electric field sensor with a field-enhancing encapsulation cover according to claim 1, characterized in that, include: Provides a conductor layer (1), an isolation layer (3), and a substrate layer (6); The lower surface of the conductor layer (1) is anodicly bonded to the isolation layer (3), and a field-enhanced conductive structure (2) is formed on the lower surface of the conductor layer (1). A second cavity (13) is formed on the isolation layer (3), and the second cavity (13) accommodates the field-enhanced conductive structure (2) to obtain the field-enhanced encapsulation cover plate; An insulating layer (5) and a device layer (4) are formed sequentially from bottom to top on the substrate layer (6). In the electric field sensing region specified in the device layer (4), a shielding electrode (7) that is vibrating relative to the device layer (4) and a sensing electrode (8) that is fixed relative to the device layer (4) are formed, and a first isolation groove (9) is formed between the shielding electrode (7) and the sensing electrode (8). A first cavity (16) corresponding to the position of the electric field sensing region is formed on the insulating layer (5) to obtain a sensitive structure; The field-enhancing encapsulation cover and the sensitive structure are anodicly bonded so that the position of the second cavity (13) corresponds to the position of the electric field sensing region, thereby obtaining the electric field sensor.

10. The preparation method according to claim 9, characterized in that, The electric field sensor is obtained by anodic bonding of the field-enhancing encapsulation cover and the sensitive structure, comprising: Multiple electrode pads (14) are symmetrically arranged on both sides of the electric field sensing region of the sensitive structure, and a second isolation groove (17) is formed between two adjacent electrode pads (14). A plurality of first lead holes (11) perpendicularly penetrating the conductor layer (1) and having the same number as the electrode pads (14) are formed on the field enhancement package cover plate, and a plurality of second lead holes (12) perpendicularly penetrating the isolation layer (3). The sensitive structure forming the plurality of electrode pads (14) is anodicly bonded to the field enhancement package cover forming the plurality of first lead holes (11) and the plurality of second lead holes (12), so that the central axis of any second lead hole (12), the central axis of the first lead hole (11) corresponding to the second lead hole (12), and the central axis of the electrode pad (14) corresponding to the second lead hole (12) are coaxial, thereby obtaining the electric field sensor.

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