Micro electric field sensing device based on electrostatic force and piezoresistive effect coupling

Abstract

The invention discloses a micro electric field sensing device based on electrostatic force and piezoresistive effect coupling, which is characterized in that the micro electric field sensing device comprises a semiconductor film which is horizontally placed and can vertically and freely vibrate, and a metal film is arranged on the first surface of the semiconductor film; the second surface of the semiconductor film is connected with a boss structure and a substrate layer through a buried oxide layer, wherein the boss structure is formed by combining the peninsula-end cross beam and the arc-petal-shaped island; the periphery of the semiconductor film is connected with the fixed part of the device layer; the device layer is provided with a metal electrode area and four arc-shaped short beams, and the metal film is connected to the metal electrode area through the arc-shaped short beams; a plurality of ion implantation areas are embedded in the arc-shaped short beam, and groove structures are arranged among the ion implantation areas; and the ion implantation region forms a Wheatstone bridge structure through the metal electrode region. The miniature electric field sensing device has the advantages of being small in size, low in cost and power consumption, high in sensitivity, high in resolution, wide in linear range, high in structural stability and the like, and can be widely applied to the field of electric field sensing.

Description

Technical Field

[0001] The present invention relates to the field of electric field sensing, and in particular to a micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect. Background Art

[0002] The power Internet of Things includes five parts: power generation, transmission, transformation, distribution and consumption. In order to obtain more real-time and comprehensive data, a large number of distributed electric field sensors need to be deployed. On the one hand, they can collect electrical data of the power grid and serve metering, control, measurement and protection devices. On the other hand, they are arranged inside electrical equipment such as transformers, insulator strings and lightning arresters to diagnose faults that are difficult to detect manually. Traditional field mill electric field measuring instruments and current transformers are large and bulky, and their application scenarios are severely limited. With the development of micro-electromechanical system (MEMS) technology and nano-processing technology, micro sensors with the characteristics of intelligence, multi-parameters, miniaturization, high precision and low power consumption are more suitable for distributed power grids. In addition, micro electric field sensors can play a key role in meteorological monitoring and lightning warning, space launch and electrical warning in the petrochemical industry.

[0003] At present, micro electric field sensors can be divided into four types according to their working principles: inductive charge principle, inverse piezoelectric effect principle, electro-optical effect principle and electrostatic force principle. Micro electric field sensors based on the electrostatic force principle have always faced problems such as low sensitivity, small measurement range, poor linearity, low processing yield and poor stability. Summary of the invention

[0004] In order to solve at least one of the technical problems existing in the prior art to a certain extent, the purpose of the present invention is to provide a new type of structural electric field sensor based on the coupling of electrostatic force and piezoresistive effect, which has the characteristics of small size, low cost and low power consumption while having the characteristics of high sensitivity, high resolution, wide linear range and high structural stability.

[0005] The technical solution adopted by the present invention is:

[0006] A micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect, comprising a horizontally placed semiconductor film capable of vertical free vibration, a metal film being arranged on the first surface of the semiconductor film; a second surface of the semiconductor film being connected to a convex platform structure combining a peninsula end cross beam and an arc-shaped island and a substrate layer through a buried oxide layer; the periphery of the semiconductor film being connected to a fixed part of a device layer;

[0007] A metal electrode area and four arc-shaped short beams are provided on the device layer, and the metal film is connected to the metal electrode area through the arc-shaped short beams; the arc-shaped short beams are inlaid with multiple ion implantation areas, and groove structures are provided between the ion implantation areas; the ion implantation areas form a Wheatstone bridge structure through the metal electrode area.

[0008] Furthermore, the metal film is deposited on top of the semiconductor film.

[0009] Furthermore, a hole structure is provided between the edge of the semiconductor film and the boss structure.

[0010] Further, the semiconductor film is an arc-shaped semiconductor film, comprising four outer arc-shaped valves;

[0011] The shape of the metal film matches the shape of the semiconductor film.

[0012] Furthermore, the boss structure combining the cross beam at the end of the peninsula and the arc-petal-shaped island is four short beams with a peninsula at the front end connected by an arc-petal-shaped island in the center.

[0013] Furthermore, the number of the ion implantation regions is four, including two transverse strain-sensitive piezoresistive regions and two longitudinal strain-sensitive piezoresistive regions; the four ion implantation regions and the metal film are electrically connected to an external circuit via a metal electrode region.

[0014] Furthermore, the ion implantation region is located at the connection between the surrounding fixed region of the semiconductor film and the arc-shaped short beam.

[0015] Furthermore, the shape of the ion implantation region is W-shaped (vertical) or cross-shaped (horizontal).

[0016] Furthermore, the ion implantation region includes an ion implantation lightly doped region and an ion implantation heavily doped region.

[0017] Furthermore, the areas of the ion-implanted lightly doped region and the ion-implanted heavily doped region are the same;

[0018] The length and width of the trench structure match the length and width of the ion implantation lightly doped region and the ion implantation heavily doped region.

[0019] The beneficial effects of the present invention include:

[0020] (1) The device of the present invention utilizes a semiconductor film with piezoresistive effect fixed on all sides to indirectly measure the electrostatic force exerted on the metal film, thereby improving the structural stability of the device, having a strong overload resistance, and being able to effectively reduce the nonlinear component in a single direction.

[0021] (2) By setting four arc-shaped short beams on the semiconductor film to form a stress concentration area, the sensitivity and resolution are improved. At the same time, the ion implantation area is set in the upper half of the short beam to improve the linearity of the output.

[0022] (3) By setting a new structure combining peninsula cross beams and arc-shaped islands at the bottom of the semiconductor film, the rigidity of the central area of ​​the semiconductor film is enhanced while further improving the sensitivity and resolution of the sensor device. Compared with square and circular diaphragms, the arc-shaped diaphragm area increases the electric field sensing area, thereby increasing the equivalent stress in the ion implantation area and improving the sensitivity of the sensor device. It is compatible with micro-nano processing technology, has low production cost, high yield, and is easy to integrate on a large scale. It can realize non-invasive measurement of AC and DC electric fields, has low static power consumption and high signal-to-noise ratio, and can intelligently monitor electrical data without affecting the normal operation of the equipment. It can be combined with multiple back-end modules to realize integrated design at the sensor node level. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the embodiments of the present invention or the drawings of related technical solutions in the prior art are introduced below. It should be understood that the drawings introduced below are only for the convenience of clearly describing some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 Schematic diagram of the cross-sectional structure of a novel micro electric field sensor device based on electrostatic force-piezoresistive effect coupling proposed in an embodiment of the present invention;

[0025] Figure 2 1 is a schematic diagram of a top view of a novel micro electric field sensor device based on electrostatic force-piezoresistive effect coupling proposed in an embodiment of the present invention;

[0026] Figure 3 1 is a schematic diagram of a bottom-up structure of a novel micro electric field sensor device based on electrostatic force-piezoresistive effect coupling proposed in an embodiment of the present invention;

[0027] Figure 4 It is a schematic diagram of displacement distribution of a novel structure micro electric field sensor device based on electrostatic force-piezoresistive effect coupling proposed in an embodiment of the present invention during operation.

[0028] Figure numerals: 1. Device layer; 2. Buried oxide layer; 3. Substrate layer; 4. Metal film area; 5. Ion implantation lightly doped area; 6. Metal electrode area; 7. Ion implantation heavily doped area; 8. Boss combining the cross beam at the end of the peninsula and the arc-shaped island; 9. Arc-shaped short beam area; 10. Hole area; 11. Groove area; 12. Semiconductor film area. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limitations of the present invention. For the step numbers in the following embodiments, they are only provided for the convenience of explanation, and the order between the steps is not limited in any way, and the execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0030] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0031] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0032] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0033] In response to the existing technical problems, the present application proposes a novel micro electric field sensor device with a combination of an arc-shaped short beam-arc-shaped membrane-peninsula cross beam and an island. In an AC or DC electric field, a large number of free charges inside a uniform metal conductor film move freely under the action of the electric field force, so that the conductor material is in an electrostatic equilibrium state. When one end of the conductor is grounded, the electrostatic balance of the metal film is broken, and the net force it receives is not zero. Under the action of the electrostatic force, the metal film deforms the semiconductor film underneath it, and the piezoresistive material area of ​​the semiconductor film converts part of the strain into a change in body resistance. By connecting the piezoresistive area with metal as a Wheatstone bridge, the resistance value can be measured, and then the electric field change can be inverted.

[0034] Based on the above objectives, the design ideas of this application are:

[0035] This application concentrates a variety of new structures on a single chip, amplifies the strain of the ion-doped area of ​​the semiconductor film with piezoresistive effect, and improves the local stiffness of the large deformation area of ​​the diaphragm. According to the principle of small deflection, the thinner diaphragm will reduce the nonlinearity and reliability of stress transfer due to the large deflection generated when it is stressed. The serpentine piezoresistive area of ​​the semiconductor film can be divided into a lightly doped area and a heavily doped area according to the ion doping concentration. The lightly doped area contains multiple wrinkles, which can ensure the overall good resistance and stress level of the piezoresistor. The heavily doped area can be used as a connecting arm of the lightly doped area to reduce the impact of the negative piezoresistive effect. The presence of the heavily doped area will reduce the sensitivity of the sensor, and the degree of reduction is proportional to the proportion of the body resistance of the heavily doped area to the total resistance of the piezoresistive area. In addition, the number of folds in the lightly doped area will also affect the performance of the sensor device. In summary, the size design, doping ion type, doping concentration and number of folds of the piezoresistive area need to be coordinated with the main structure of the device.

[0036] Based on the above design ideas, this embodiment designs a micro electric field sensor device with high sensitivity and wide linear range, specifically:

[0037] A novel structural electric field sensor with an arc-shaped short beam-arc-petal membrane-peninsula cross beam and island combination, comprising a horizontally placed semiconductor film that can vibrate vertically freely, a structure combining a peninsula end cross beam and an arc-petal island and a substrate layer are provided below the semiconductor film, the semiconductor film and the boss structure combining the peninsula end cross beam and the arc-petal island and the substrate layer are connected through a buried oxide layer, four arc-shaped short beams and a metal film are provided above the semiconductor film, the upper half of the four arc-shaped short beams are inlaid with ion implantation areas, groove structures are provided between the ion implantation areas of the arc-shaped short beams, and metal electrode areas are provided above the fixed areas around the semiconductor film.

[0038] As an implementation mode, the metal film and the metal electrode region are covered on the top of the semiconductor film by deposition.

[0039] As an optional implementation, a hole structure is provided between the edge of the semiconductor film and the central boss in the horizontal direction. The number and radius of the hole structure affect the local stiffness of the sensor device and the strain sensitivity of the piezoresistive area, and need to be adjusted according to specific needs.

[0040] In some embodiments, the semiconductor film is an arc-shaped semiconductor film, including four outer arc-shaped valves, and the arc radius affects the deformation deflection of the center of the diaphragm and the average strain of the ion implantation area, which needs to be regulated according to actual needs. The shape of the metal film is similar to the shape of the semiconductor film. In other embodiments, the semiconductor film can be square or quasi-circular, etc. This application does not limit the shape of the semiconductor film, and semiconductor films of other shapes also fall within the protection scope of this application.

[0041] As an implementation method, the number of the ion implantation regions is four, including two transverse strain-sensitive piezoresistive regions and two longitudinal strain-sensitive piezoresistive regions. The four ion implantation regions and the top metal film are electrically connected to an external circuit via a metal electrode region.

[0042] As an implementation method, the ion implantation area is in the shape of a W-type (vertical) and a stem-type (lateral) to maximize the conversion of strain energy in the strain concentration area of ​​the sensor device. The longitudinal piezoresistive area and the transverse piezoresistive area follow the principle of symmetry to ensure that the resistance changes of the bridge arms of the Wheatstone relative bridge are the same and the resistance changes of adjacent bridge arms are opposite, thereby achieving differential amplification output.

[0043] Further preferably, the lightly doped region of the W-shaped longitudinal strain sensitive region of the ion implantation region is three long strip regions perpendicular to the edge of the film, with a small number of folds, which is more suitable for longitudinal strain changes with favorable conversion length.

[0044] Further preferably, the lightly doped region of the dry-type longitudinal strain sensitive region of the ion implanted region is 5 long strip regions parallel to the edge of the film, having a large number of folds and being more suitable for lateral strain changes with favorable conversion width.

[0045] In some embodiments, the ion implantation region includes a heavily doped region and a lightly doped region of the ion implantation region, wherein the heavily doped region serves as a connecting arm between the lightly doped regions and between the lightly doped regions and the metal electrode regions, and its shape can be diverse, such as a long strip, a rectangular splicing, etc.

[0046] As an implementation mode, the lightly doped and heavily doped ion implanted regions of the four bridge arms of the Wheatstone bridge have the same area, which theoretically makes the resistance changes of the four bridge arms the same while avoiding the zero drift problem.

[0047] As an implementation method, the length and width of the trench structure should match the length of the lightly doped region and the heavily doped region of the ion implantation region, which can further amplify the effective strain change.

[0048] In some embodiments, the boss structure combining the cross beam at the end of the peninsula and the arc-shaped island is four short beams with a peninsula at the front end connected by an arc-shaped island in the center. According to the Euler-Bernukli beam principle, the side length of the structure is much smaller than the side length of the membrane. It is assumed that the cross section of the beam is infinitely rigid in its own plane, that is, the deflection of the same cross section along the width direction remains unchanged. At this time, the four film edges can be regarded as rigid bodies, and each beam structure generates a distributed reaction force along the length of the beam to maintain force balance. When the electrostatic force is loaded to the front surface of the membrane, the reaction force can be simplified to the concentrated load and bending moment at the end of the cross beam. Under the action of the bending moment, the deformation of this section matches the shape of the diaphragm, and its size and direction are determined by the cross section that bears the deformation. The proposed peninsula port transfers it to the piezoresistive sensitive area. The size of the island affects the local stiffness of the sensor device and the strain sensitivity of the piezoresistive area, and needs to be regulated according to specific needs.

[0049] The structure of the above device is described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] like Figure 1 , Figure 2 and Figure 3 As shown, this embodiment provides a novel structure micro electric field sensor device based on electrostatic force-piezoresistive effect coupling, including a device layer 1, a buried oxide layer 2 and a substrate layer 3, wherein the device layer 1 is connected to the substrate layer 3 through the buried oxide layer 2. The device layer is provided with a metal film 4 arranged along the xy direction and can vibrate vertically along the z direction. Below the metal film 4 is a semiconductor film 12 of similar shape and size exposed by micro-nano processing technology, which is connected to the fixed part of the device layer 1 on all sides. A metal electrode region 6 is deposited above the fixed part of the device layer 1, and the metal film 4 is grounded through the metal electrode region 6 to release body charge. An arc-shaped short beam region 9 is provided above the metal film 4, and its surroundings are fixed to the fixed part of the device layer 1. The upper half of the arc-shaped short beam region 9 is provided with ion-implanted light-heavy doping regions 5 and 7, and a groove structure 11 is provided therebetween, and the ion-implanted regions 5 and 7 form a Wheatstone bridge structure through the metal electrode region 6. A boss structure 8 combining a peninsula-end cross beam and an arc-petal-shaped island is provided below the semiconductor film, which is connected to the semiconductor film 12 through the buried oxide layer 2. The hole structure 10 penetrates the semiconductor film 12 and the metal film 4 and is located between the boss structure 8 and the edge of the semiconductor film 12 in the horizontal direction.

[0051] like Figure 4 As shown, the schematic diagram of the working displacement distribution of the device in the finite element numerical simulation software of this embodiment is as follows Figure 4 As shown, the center of the film is deformed significantly and can effectively respond to changes in the spatial electric field.

[0052] In summary, the present invention uses a semiconductor film with a piezoresistive effect fixed on all sides to indirectly measure the electrostatic force on the metal film, improves the stability of the device structure, has a strong overload resistance, and can effectively reduce the nonlinear component in a single direction. By setting four arc-shaped short beams on the semiconductor film to form a stress concentration area, the sensitivity and resolution are improved, and the ion implantation area is set in the upper half of the short beam to improve the linearity of the output. By setting a new structure combining a peninsula cross beam and an arc-shaped island at the bottom of the semiconductor film, the rigidity of the central area of ​​the semiconductor film is enhanced while further improving the sensitivity and resolution of the sensor device. Compared with square and circular diaphragms, the arc-shaped diaphragm area increases the electric field sensing area, thereby increasing the equivalent stress of the ion implantation area and improving the sensitivity of the sensor device. It is compatible with micro-nano processing technology, has low production cost, high yield rate, and is easy to integrate on a large scale. It can realize non-invasive measurement of AC and DC electric fields, has low static power consumption and high signal-to-noise ratio, and intelligently monitors electrical data without affecting the normal operation of the equipment. It can be combined with multiple back-end modules to achieve an integrated design at the sensor node level.

[0053] In the above description of this specification, the description with reference to the terms "one embodiment / example", "another embodiment / example" or "certain embodiments / examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

[0055] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the above embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect, characterized in that: It comprises a semiconductor film which is placed horizontally and can vibrate vertically freely, wherein a metal film is arranged on the first surface of the semiconductor film; and a boss structure combining a peninsula end cross beam and an arc-shaped island and a substrate layer are connected to the second surface of the semiconductor film through a buried oxide layer; The periphery of the semiconductor film is connected to the fixed part of the device layer; A metal electrode area and four arc-shaped short beams are provided on the device layer, and the metal film is connected to the metal electrode area through the arc-shaped short beams; the arc-shaped short beams are inlaid with multiple ion implantation areas, and groove structures are provided between the ion implantation areas; the ion implantation areas form a Wheatstone bridge structure through the metal electrode area.

2. A micro electric field sensor device based on coupling of electrostatic force and piezoresistive effect according to claim 1, characterized in that: The metal film is deposited on top of the semiconductor film.

3. The micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect according to claim 1, characterized in that: A hole structure is provided between the edge of the semiconductor film and the boss structure.

4. The micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect according to claim 1, characterized in that: The semiconductor film is an arc-shaped semiconductor film, comprising four outer arc-shaped valves; The shape of the metal film matches the shape of the semiconductor film.

5. The micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect according to claim 1, characterized in that: The boss structure combining the cross beam at the end of the peninsula and the arc-petal-shaped island is composed of four short beams with a peninsula at the front end connected by an arc-petal-shaped island in the center.

6. The micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect according to claim 1, characterized in that: The number of the ion implantation regions is four, including two transverse strain-sensitive piezoresistive regions and two longitudinal strain-sensitive piezoresistive regions; the four ion implantation regions and the metal film are electrically connected to an external circuit via a metal electrode region.

7. The micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect according to claim 1, characterized in that: The ion implantation area is located at the connection between the surrounding fixed area of ​​the semiconductor film and the arc-shaped short beam.

8. The micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect according to claim 1, characterized in that: The shape of the ion implantation area is W-shaped or stem-shaped.

9. The micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect according to claim 1, characterized in that: The ion implantation region includes an ion implantation lightly doped region and an ion implantation heavily doped region.

10. The micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect according to claim 9, characterized in that: The areas of the ion-implanted lightly-doped region and the ion-implanted heavily-doped region are the same; The length and width of the trench structure match the length and width of the ion implantation lightly doped region and the ion implantation heavily doped region.

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