CN113625064A

CN113625064A - Electric field sensor

Info

Publication number: CN113625064A
Application number: CN202010389820.XA
Authority: CN
Inventors: 彭春荣; 王子龙; 毋正伟; 夏善红
Original assignee: Aerospace Information Research Institute of CAS
Current assignee: Aerospace Information Research Institute of CAS
Priority date: 2020-05-09
Filing date: 2020-05-09
Publication date: 2021-11-09
Anticipated expiration: 2040-05-09
Also published as: CN113625064B

Abstract

An electric field sensor comprising: a substrate (1); the resonators (2) are arranged on a plane parallel to the surface outside the surface of the substrate (1) through the supporting structure (3), the resonators (2) are arranged from one end of the plane to the other end opposite to the end, the side walls of the resonators (2) are opposite to each other and are mutually coupled, and the resonators (2) can vibrate along the direction parallel to the plane; the induction electrodes (4) are arranged on the outer side walls of the two resonators (2) on the two ends of the plane; the driving structure (5) is arranged on the outer side of at least one resonator (2) of the two resonators (2) on the two ends of the plane, and the driving structure (4) is disconnected from the resonators (2); and the polarized medium layer (6) is arranged on one resonator (2) of the two resonators (2) at the two ends of the plane. The electric field sensor has high sensitivity, is small in size, is beneficial to realizing batch manufacturing and system integration, and reduces the cost.

Description

Electric field sensor

Technical Field

The invention relates to the field of sensors and Micro-Electro-Mechanical systems (MEMS for short), in particular to a torque type Micro electric field sensor based on modal localization.

Background

The MEMS-based electric field sensor is a device for measuring the electric field intensity, and has very important functions in aspects of meteorological detection, aerospace, industrial production, smart power grids, national defense and military and scientific research. And the sensitivity requirement is higher in the directions of target detection, high-sensitivity electrostatic measurement and the like.

According to different working principles, electric field sensors can be divided into two categories, namely a charge induction type and an optical type, and the most prominent problems of the early traditional electric field sensors based on the charge induction principle, such as a double-ball type and a rotary-vane type, are that the size is large and the cost is high; with the development of MEMS technology, an electric field sensor based on MEMS technology is proposed, and for example, a torsional electric field sensor with excellent performance is smaller, easier to manufacture and integrate than a conventional electric field sensor, but is limited by the limitation of the working principle, and also has a disadvantage of insufficient sensitivity.

Disclosure of Invention

Technical problem to be solved

In view of the prior art, the present invention provides a torque type micro electric field sensor based on mode localization, which is used to at least partially solve the above technical problems.

(II) technical scheme

The present invention provides an electric field sensor comprising: a substrate 1; at least two resonators 2 arranged on a plane parallel to the surface outside the surface of the substrate 1 through a support structure 3, wherein the resonators 2 are arranged from one end of the plane to the other end opposite to the end, the side walls of the resonators 2 are opposite to each other and are mutually coupled, and the resonators 2 can vibrate along the direction parallel to the plane; the induction electrodes 4 are arranged on the outer side walls of the two resonators 2 at the two ends of the plane; the driving structure 5 is arranged on the outer side of at least one resonator 2 in the two resonators 2 at the two ends of the plane, and the driving structure 4 is disconnected from the resonators 2; and the polarized medium layer 6 is arranged on one resonator 2 of the two resonators 2 at the two ends of the plane.

Optionally, the resonator 2 includes a mass 21 and a strut 22; the polarization medium layer 6 is arranged on the mass block 21, one end of the support beam 22 is fixed with the mass block 21, and the other end is fixed on the substrate 1 through the support structure 3.

Optionally, the sensing electrode 4 includes a movable portion 41 and an immovable portion 42, the movable portion 41 is disposed on an outer sidewall of the resonator 2, and the immovable portion 42 is fixed on the substrate 1 through the support structure 4.

Alternatively, the resonators 2 are directly coupled to each other through an electrostatic coupling connection or a mechanical beam.

Optionally, at least one pair of the sensing electrodes 4 is disposed on an outer sidewall of each of the two resonators 2 at two end positions of the plane.

Optionally, the driving structure 5 comprises an electrostatic driving structure, a piezoelectric driving structure, a thermal driving structure or a magnetic driving structure.

Optionally, the material of the polarization medium layer 6 includes silicon nitride, or an insulating material with a dielectric constant higher than a preset value, or an electret, or a piezoelectric material.

Optionally, the resonator 2 includes at least 2N of the support beams 22 and N of the masses 21, where N is a positive integer. .

Optionally, the sensing electrode 4 is a strip structure, and the driving structure 5 is a flat plate structure.

Optionally, the polarization dielectric layer 6 is polarized with a probe gap or with an applied electrode.

(III) advantageous effects

The invention provides a torque type micro electric field sensor based on modal localization, which is characterized in that energy is localized in a local part in the working process of the sensor by the aid of the layout of structures such as a resonator, an induction electrode and a polarized medium layer by means of the modal localization principle, electric field intensity is converted into rigidity disturbance, the rigidity disturbance is converted into an amplitude ratio to measure the intensity of the electric field, and accordingly sensitivity of the sensor is improved. Moreover, the electric field sensor with the structure can be manufactured by adopting the MEMS technology, thereby being beneficial to realizing batch manufacturing and system integration and simultaneously reducing the cost.

Drawings

FIG. 1 is a schematic diagram illustrating a torque-type micro electric field sensor provided in an embodiment of the present invention;

FIG. 2 schematically illustrates a top view of a torque-based micro-electric field sensor provided by an embodiment of the present invention;

FIG. 3 schematically illustrates a detailed block diagram of a mechanically coupled resonator of an electric field sensor provided by an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating a manufacturing flow chart of a torque-based micro electric field sensor based on mode localization provided by an embodiment of the invention;

FIG. 5A is a schematic diagram showing a structure of a probe used in the space polarization method of the probe according to the embodiment of the present invention;

FIG. 5B is a flow chart that schematically illustrates a method for polarizing an applied electrode, in accordance with an embodiment of the present invention;

FIG. 6 is a flow chart schematically illustrating a method for polarizing an additional electrode provided by an embodiment of the present invention.

[ reference numerals ]

1-substrate, 2-resonator, 21-mass block, 22-corbel, 3-supporting structure, 4-induction electrode, 41-movable part, 42-immovable part, 5-driving structure, 6-polarization medium layer, 7-mechanical beam and 8-probe.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings.

The embodiment of the invention provides a torque type micro electric field sensor which comprises a substrate, wherein a driving structure, an induction electrode, a polarized medium layer and a plurality of resonators are fixed on the substrate through a supporting structure (fixed anchor point). The electric field sensor can utilize the principle of modal localization to enable energy to be localized in the working process of the sensor, the electric field intensity is converted into rigidity disturbance, and then the rigidity disturbance is converted into amplitude ratio, so that the sensitivity of the sensor is improved. This is done by way of specific examples.

Fig. 1 schematically shows a structural view of a torque type micro electric field sensor provided in the present embodiment, and as shown in fig. 1, the electric field sensor may include, for example:

a substrate 1, on which at least two resonators 2 are arranged, the resonators 2 are arranged on a plane parallel to the surface outside the surface of the substrate 1 through a support structure 3, the resonators 2 are arranged from one end of the plane to the other end (as shown in the direction of fig. 1) opposite to the end, the side walls of the resonators 2 are opposite to each other and are coupled with each other, and the resonators 2 can vibrate along the direction parallel to the plane. In a feasible manner of this embodiment, the number of the resonators 2 is three, one resonator 2 is respectively disposed at the left end and the right end, one resonator 2 is disposed in the middle, and the sidewalls of the three resonators 2 are opposite to each other, so that the resonators can perform reciprocating vibration.

In a possible manner of the present embodiment, each resonator 2 includes a mass 21 and a strut 22. The beams 22 are fixed to the mass 21 at one end and to the substrate 1 at the other end via the support structure 3, whereby the resonator 2 is fixed so that the resonator 2 can vibrate in the horizontal direction in the direction shown in fig. 1. The resonator 2 may include at least 2N corbels 22 and N masses 21, where N is a positive integer, in this embodiment, the masses 21 are configured as square masses or rectangular masses, the number of the corbels 21 is one, the number of the corbels 22 is 4, and the 4 corbels 22 are symmetrical with respect to the center of the masses, so that the stress of the masses 21 during the vibration process is uniform. The number and the positions of the mass blocks and the support beams in the resonator 2 are not limited, and the horizontal vibration of the resonator 2 can be met.

And the induction electrodes 4 are arranged on the outer side walls of the two resonators 2 at two ends of the plane. As shown in fig. 1, the outer sidewalls of the left and right resonators 2 are provided with the inductive electrodes 4. The sensing electrode 4 may comprise a movable portion 41 and an immovable portion 42, the movable portion 41 being provided on an outer sidewall of the resonator 2, and the immovable portion 42 being fixed on the substrate 1 through the support structure 3. In a feasible mode of the present embodiment, at least one pair of sensing electrodes 4 is disposed on the outer side wall of each resonator 2 of the two resonators 2 at the left and right ends. As shown in fig. 1, in this embodiment, a pair of sensing electrodes 4 is disposed on the outer sidewall of the resonator 2, and the specific number of pairs can be set according to the actual number, which is not limited in the present invention. The sensing electrode 4 may be a strip structure, and the specific structure of the sensing electrode is not limited in the present invention and may be set according to actual requirements.

And the driving structure 5 is arranged on the outer side of at least one resonator 2 in the two resonators 2 at the two ends of the plane, the driving structure 4 is disconnected from the resonators 2, and the driving structure 5 is used for horizontal vibration of the resonators 2. As shown in fig. 1, the driving structure 5 is disposed on the side of the resonator 2 at the rightmost end, and the driving structure 5 may be disposed on the side of the resonator 2 at the leftmost end (not shown). The driving structure 5 includes an electrostatic driving structure, a piezoelectric driving structure, a thermal driving structure, or a magnetic driving structure. In the present embodiment, the electrostatic drive structure is selected to drive the resonator 2. The drive structure 5 may be a strip structure.

And the polarized medium layer 6 is arranged on one resonator 2 of the two resonators 2 at the two ends of the plane. As shown in fig. 1, the polarization medium layer 6 is attached to the mass block 21 of the rightmost resonator 2, and the polarization medium layer 6 is attached to the mass block 21 of the leftmost resonator 2 (not shown). The material of the polarization medium layer 6 includes silicon nitride, or any other insulating material with a dielectric constant higher than a predetermined value, or electret or piezoelectric material. The shape of the polarized medium layer 6 can be cuboid, cylinder, strip, ring or other shapes, the specific shape can be set according to the actual requirement, and the specific structure is not limited in the invention.

In a possible manner of the present embodiment, the resonators 2 are directly coupled to each other through an electrostatic coupling connection or a mechanical beam. As shown in fig. 2, the electrostatic coupling connection means that a direct current voltage (V shown in fig. 2) is applied to the resonator 2 at the middle position, the two resonators 2 at the both end positions are grounded (Gnd shown in fig. 2), and the connection is achieved by a weak coupling effect generated by the direct current coupling voltage. As shown in fig. 3, the mechanical beam direct coupling connection means that the resonators 2 are connected by using an elongated mechanical beam 7, and the arrangement is such that the three resonators are coupled together by means of mechanical coupling. The electrostatic coupling is that three syntonizers are not continuous each other, and mechanical roof beam direct coupling connects that three syntonizers are direct to be connected, but no matter connect with the mode, electric field sensor can both produce the mode localization phenomenon, and then utilizes this phenomenon to measure electric field strength.

In a feasible manner of this embodiment, the substrate 1 may include two or more sets of the electric field sensor structures described above.

With continued reference to fig. 2, a polarized medium layer 6 is disposed on the mass block 21 of the resonator 2 at the lowermost end in the direction shown in fig. 2, and a driving structure 5 is disposed under the resonator 2 at the lowermost end, and the resonators 2 are electrostatically coupled. The working principle of the torque type electric field sensor is as follows:

application of an alternating voltage to the drive structure 5 generates an alternating electrostatic force on the lowermost resonator 2, thereby generating a cyclic amplitude of reciprocation of the resonator 5. Since the resonators 2 at the intermediate positions are electrostatically coupled by applying a dc coupling voltage, the uppermost resonator 2 and the lowermost resonator 2 are also vibrated in the same amplitude and in opposite directions. When an external electric field (electric field to be measured) exists, the polarized medium layer 6 generates torque on the resonator 2 at the lowest end, so that the resonator 2 at the lowest end generates rigidity disturbance, and a mode localization phenomenon is generated, so that the vibration amplitude of the resonator 2 at the lowest end is increased, the vibration amplitude of the resonator 2 at the highest end is decreased, and the amplitude change causes different induced currents of the two groups of induction electrodes 4, therefore, the different ratios of the induced currents of the two groups of induction electrodes 4 can be utilized to determine the electric field intensity of the electric field to be measured.

In addition, the direction of the induced electric field of the electric field sensor is a horizontal electric field, and a three-position electric field sensor can be formed by assembling three sensors.

The electric field sensor provided by the embodiment can be manufactured by adopting a micro-nano processing technology, a Micro Electro Mechanical System (MEMS) technology, an SOI MEMS, a bulk silicon process, a surface process or a precision machining technology. A manufacturing process flow based on MEMS technology is provided below.

As shown in fig. 4, the method includes the following steps:

and S1, plating a silicon nitride film on the substrate (SOI silicon wafer) by adopting PECVD, photoetching the silicon nitride layer, and removing the silicon nitride and the photoresist.

And S2, plating a metal aluminum layer by using CVD, and photoetching and removing the aluminum and the photoresist.

And S3, photoetching the device layer of the SOI silicon wafer, etching the device layer by adopting DRIE, and utilizing the over-etching stage of the DRIE and adopting a notching effect to facilitate the release of the subsequent device layer.

And S4, removing the photoresist, and etching the oxide layer by adopting an HF wet method to finally release the device layer.

And S5, polarizing the dielectric layer to obtain the polarized dielectric layer.

In S5, the dielectric layer may be polarized by probe gap polarization or by external electrode polarization.

The cylinder in FIG. 5A is a probe to which a high voltage V is applied from the outside to the probe 8₁And applied to the resonator, a polarizing effect can be achieved on the dielectric layer. FIG. 5B is a schematic diagram of a structure of a probe polarization method. The electrode layer is kept grounded, and the dielectric layer is polarized in a non-contact manner by applying a high voltage to the probe.

FIG. 6 is a process diagram of an applied electrode polarization scheme. Specifically, a dielectric layer (including a resonator beam) is sputtered or deposited on the resonator, electrode layers are respectively led out on the device layer and the dielectric layer, and finally the dielectric layer can be polarized by applying high voltage to the two electrode layers, so that the polarized dielectric layer is obtained.

According to the torque type micro electric field sensor based on the modal localization, the layout of the structures such as the resonator, the induction electrode and the polarized medium layer is adopted, the modal localization principle is utilized to enable the energy in the working process of the sensor to be localized locally, the electric field intensity is converted into the rigidity disturbance, the rigidity disturbance is converted into the amplitude ratio to measure the electric field intensity, and therefore the sensitivity of the sensor is improved. Moreover, the electric field sensor with the structure has small volume, can be manufactured by adopting the MEMS technology, is beneficial to realizing batch manufacturing and system packaging integration, simultaneously reduces the cost, and is beneficial to the wide application of the electric field sensor in the aspects of meteorological detection, aerospace, industrial production, smart grid, national defense military, scientific research and the like.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electric field sensor, comprising:

a substrate (1);

at least two resonators (2) arranged on a plane parallel to the surface of the substrate (1) outside the surface through a supporting structure (3), wherein the resonators (2) are arranged from one end of the plane to the other end opposite to the end, the side walls of the resonators (2) are opposite to each other and are mutually coupled, and the resonators (2) can vibrate along the direction parallel to the plane;

the induction electrodes (4) are arranged on the outer side walls of the two resonators (2) at the two ends of the plane;

the driving structure (5) is arranged on the outer side of at least one resonator (2) in the two resonators (2) at the two ends of the plane, and the driving structure (4) is disconnected from the resonators (2);

and the polarized medium layer (6) is arranged on one resonator (2) of the two resonators (2) at the two ends of the plane.

2. Electric field sensor according to claim 1, characterized in that the resonator (2) comprises a mass (21) and a corbel (22);

the polarization medium layer (6) is arranged on the mass block (21), one end of the support beam (22) is fixed with the mass block (21), and the other end of the support beam is fixed on the substrate (1) through the support structure (3).

3. Electric field sensor according to claim 1, characterized in that the sensing electrode (4) comprises a movable part (41) and an immovable part (42), the movable part (41) being provided at an outer side wall of the resonator (2), the immovable part (42) being fixed to the substrate (1) by the support structure (4).

4. Electric field sensor according to claim 1, characterized in that the resonators (2) are directly coupled to each other by means of an electrostatic coupling connection or a mechanical beam.

5. The electric field sensor according to claim 1, characterized in that at least one pair of said sensing electrodes (4) is provided on the outer side wall of each of said two resonators (2) in the two end positions of said plane.

6. Electric field sensor according to claim 1, characterized in that the actuation structure (5) comprises an electrostatic actuation structure, a piezoelectric actuation structure, a thermal actuation structure or a magnetic actuation structure.

7. Electric field sensor according to claim 1, characterized in that the material of said layer of polarization medium (6) comprises silicon nitride, or an insulating material with a dielectric constant higher than a preset value, or an electret, or a piezoelectric material.

8. Electric field sensor according to claim 2, characterized in that the resonator (2) comprises at least 2N of said corbels (22) and N of said masses (21), where N is a positive integer.

9. Electric field sensor according to claim 1, characterized in that the sensing electrode (4) is a strip structure and the driving structure (5) is a plate structure.

10. Electric field sensor according to claim 1, characterized in that the polarizing dielectric layer (6) is polarized with a probe gap or with an applied electrode.