A micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect

Abstract

The present invention discloses a micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect, which is characterized in that it includes a semiconductor thin film horizontally placed and capable of vibrating vertically and freely, and a metal thin film is provided on the first surface of the semiconductor thin film; the second surface of the semiconductor thin film is connected to a convex structure combining a peninsula-end cross beam and an arc-lobe-shaped island through a buried oxide layer and a substrate layer; the periphery of the semiconductor thin film is connected to the fixed part of the device layer; a metal electrode region and four arc-shaped short beams are provided on the device layer, and the metal thin film is connected to the metal electrode region through the arc-shaped short beams; multiple ion implantation regions are embedded in the arc-shaped short beams, and a trench structure is provided between the ion implantation regions; the ion implantation regions form a Wheatstone bridge structure through the metal electrode region. The micro electric field sensor device of the present invention has the characteristics of high sensitivity, high resolution, wide linear range and high structural stability while meeting the requirements of small volume, low cost and low power consumption, 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, power transmission, power transformation, power distribution, and power 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, it can collect electrical data of the power grid and serve metering, control, measurement, and protection devices. On the other hand, it is arranged inside electrical equipment such as transformers, insulator strings, and lightning arresters to diagnose faults that are difficult to detect manually. Traditional field mill type 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 nanomanufacturing technology, micro sensors with characteristics such as 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] Current micro electric field sensors can be divided into four types according to the working principle: induced charge principle, inverse piezoelectric effect principle, electro-optic effect principle, and electrostatic force principle. However, for micro electric field sensors based on the electrostatic force principle, problems such as low sensitivity, small measurement range, poor linearity, low processing yield, and poor stability have always been faced. Summary of the Invention

[0004] 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 structure electric field sensor based on the coupling of electrostatic force and piezoresistive effect, which has the characteristics of high sensitivity, high resolution, wide linear range, and high structural stability while meeting the requirements of small volume, low cost, and low power consumption.

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

[0006] A micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect, including a semiconductor thin film placed horizontally and vibrating vertically freely. A metal thin film is provided on the first surface of the semiconductor thin film; the second surface of the semiconductor thin film is connected to a convex structure combined with a peninsula-end cross beam and an arc-lobe island through a buried oxide layer and a substrate layer; the periphery of the semiconductor thin film is connected to the fixed part of the device layer;

[0007] The device layer is provided with a metal electrode region and four arc-shaped short beams, and the metal thin film is connected to the metal electrode region through the arc-shaped short beams; multiple ion implantation regions are embedded in the arc-shaped short beams, and a trench structure is arranged between the ion implantation regions; the ion implantation regions form a Wheatstone bridge structure through the metal electrode region.

[0008] Further, the metal thin film covers the top of the semiconductor thin film in a deposited form.

[0009] Further, a hole structure is arranged between the edge of the semiconductor thin film and the boss structure.

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

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

[0012] Further, the boss structure combined by the peninsula-end cross beam and the arc-lobe-shaped island is four short beams with a peninsula at the front end connected by an arc-lobe-shaped island at the center.

[0013] Further, 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 thin film are electrically connected through the metal electrode region and an external circuit.

[0014] Further, the ion implantation regions are located at the connection between the fixed regions around the semiconductor thin film and the arc-shaped short beams.

[0015] Further, the shape of the ion implantation regions is W-shaped (longitudinal) or dry-shaped (transverse).

[0016] Further, the ion implantation regions include an ion implantation lightly doped region and an ion implantation heavily doped region.

[0017] Further, the areas of the ion implantation lightly doped region and the ion implantation 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 indirectly measures the electrostatic force received by the metal thin film by using a semiconductor thin film with piezoresistive effect fixed around, improves the structural stability of the device, has a strong anti-overload ability, and can effectively reduce the non-linear component in a single direction.

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

[0022] (3) By setting a new structure combining a peninsula cross beam and arc lobe-shaped islands at the bottom of the semiconductor thin film, while enhancing the stiffness of the central area of the semiconductor thin film, the sensitivity and resolution of the sensor device are further improved. Compared with square and circular diaphragms, the arc lobe-shaped diaphragm area increases the electric field induction 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 achieve non-invasive measurement of AC and DC electric fields, has low static power consumption and high signal-to-noise ratio by itself, and can intelligently monitor electrical data without affecting the normal operation of the device. It can be combined with multiple backend modules to achieve an integrated design at the sensing node level. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

[0028] Reference numerals: 1, device layer; 2, buried oxide layer; 3, substrate layer; 4, metal thin film region; 5, ion implanted lightly doped region; 6, metal electrode region; 7, ion implanted heavily doped region; 8, boss formed by the combination of a peninsula end cross beam and an arc-shaped lobe island; 9, arc-shaped short beam region; 10, hole region; 11, trench region; 12, semiconductor thin film region. Detailed implementation manners

[0029] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention. For the step numbers in the following embodiments, they are only set for the convenience of explanation and description, and no limitation is imposed on the order between the steps. The execution order of each step in the embodiments 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 for the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 construed as a limitation of the present invention.

[0031] In the description of the present invention, the meaning of several is one or more, the meaning of multiple is two or more, greater than, less than, exceeding, etc. are understood as not including the present number, above, below, within, etc. are understood as including the present number. If the first and second are described only for the purpose of distinguishing technical features, they should not be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0032] In the description of the present invention, unless otherwise clearly defined, words such as setting, installing, connecting, etc. should be understood in a broad sense. Those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with 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 a further optional embodiment, a hole structure is provided between the edge of the semiconductor thin film and the horizontal direction of the central boss. The number and radius of the hole structure affect the local stiffness of the sensor device and the strain sensitivity of the piezoresistive region, and need to be adjusted according to specific requirements.

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

[0041] As an embodiment, 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 thin film are electrically connected through the metal electrode region and the external circuit.

[0042] As an embodiment, the shapes of the ion implantation regions are W-shaped (longitudinal) and dry-shaped (transverse), aiming to maximize the conversion of strain energy in the strain concentration region of the sensor device. The longitudinal piezoresistive region and the transverse piezoresistive region follow the symmetry principle to ensure that the resistance changes of the arms of the formed Wheatstone relative bridge are the same, the resistance changes of adjacent arms are opposite, and differential amplification output is realized.

[0043] Further preferably, the lightly doped regions of the W-shaped longitudinal strain-sensitive regions of the ion implantation regions are three strip-shaped regions perpendicular to the film edge, with fewer folds and more suitable for converting longitudinal strain changes with favorable length.

[0044] Further preferably, the lightly doped regions of the dry-shaped longitudinal strain-sensitive regions of the ion implantation regions are five strip-shaped regions parallel to the film edge, with more folds and more suitable for converting transverse strain changes with favorable width.

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

[0046] As an embodiment, the areas of the lightly doped and heavily doped regions of the ion implantation regions serving as the four arms of the Wheatstone bridge are the same, theoretically making the change amounts of the resistances of the four arms the same while avoiding the zero-drift problem.

[0047] As an implementation manner, the length and width of the trench structure should match the lengths 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 implementation manners, the boss structure formed by the combination of the peninsula-ended cross beam and the arc-lobe-shaped island is four short beams with a front end of a peninsula connected by an arc-lobe-shaped island at the center. According to the Euler-Bernoulli beam principle, the side length of the structure is much smaller than the side length of the membrane. Assuming 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 thin film edges can be regarded as rigid bodies, and each beam structure generates a distributed reaction force along the length direction of the beam to maintain force balance. When an electrostatic force is applied to the front surface of the membrane, this reaction force can be simplified into a concentrated load and a 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 magnitude and direction are determined by the cross-section that bears the deformation. The designed 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 adjusted according to specific requirements.

[0049] The structure of the above-mentioned device will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0050] As Figure 1 、 Figure 2 and Figure 3 shown, this embodiment provides a novel structure micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect, including a device layer 1, a buried oxide layer 2 and a substrate layer 3, wherein the device layer 1 is connected through the buried oxide layer 2 and the substrate layer 3. The device layer is provided with a metal thin film 4 arranged along the xy direction and capable of vibrating vertically along the z direction. Below the metal thin film 4 is a semiconductor thin film 12 with a similar shape and size exposed through micro-nano processing technology, and its periphery is connected to the fixed part of the device layer 1. Above the fixed part of the device layer 1, a metal electrode region 6 is deposited, and the metal thin film 4 is grounded through the metal electrode region 6 to release the body charge. Above the metal thin film 4 is an arc-shaped short beam region 9, and its periphery is 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 implantation lightly-heavily doped regions 5 and 7, and a trench structure 11 is arranged therebetween. The ion implantation regions 5 and 7 form a Wheatstone bridge structure through the metal electrode region 6. Below the semiconductor thin film is a boss structure 8 formed by the combination of a peninsula-ended cross beam and an arc-lobe-shaped island, which is connected to the semiconductor thin film 12 through the buried oxide layer 2. The hole structure 10 penetrates through the semiconductor thin film 12 and the metal thin film 4, and is horizontally located between the boss structure 8 and the edge of the semiconductor thin film 12.

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

[0052] In summary, the present invention indirectly measures the electrostatic force received by the metal thin film by using a semiconductor thin film with piezoresistive effect fixed around, improves the structural stability of the device, has strong anti-overload ability, and can effectively reduce the non-linear component in a single direction. By setting four arc-shaped short beams on the semiconductor thin film to form a stress concentration area, the sensitivity and resolution are improved. At the same time, the ion implantation area is set on the upper half of the short beam, which can improve the linearity of the output. By setting a new structure combining a peninsula cross beam and arc lobe-shaped islands at the bottom of the semiconductor thin film, while enhancing the stiffness of the central area of the semiconductor thin film, the sensitivity and resolution of the sensor device are further improved. Compared with square and circular diaphragms, the arc lobe-shaped diaphragm area increases the electric field induction 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, 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 by itself, and can intelligently monitor electrical data without affecting the normal operation of the device. It can be combined with multiple back-end modules to realize the integrated design at the sensor node level.

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

[0054] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

[0055] The above is a specific description of the preferred embodiment of the present invention, but the present invention is not limited to the above embodiments. Those skilled in the art can also make various equivalent deformations or substitutions without departing from the spirit of the present invention, and these equivalent deformations 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 includes a semiconductor thin film that is horizontally placed and can vibrate vertically freely. A metal thin film is provided on the first surface of the semiconductor thin film; the second surface of the semiconductor thin film is connected to a boss structure combined with a peninsula-ended cross beam and an arc-lobe-shaped island and a substrate layer through a buried oxide layer; The periphery of the semiconductor thin film is connected to the fixed part of the device layer; A metal electrode region and four arc-shaped short beams are provided on the device layer. The metal thin film is connected to the metal electrode region through the arc-shaped short beams; multiple ion implantation regions are embedded in the arc-shaped short beams, and a trench structure is provided between the ion implantation regions; the ion implantation regions form a Wheatstone bridge structure through the metal electrode region; A hole structure is provided between the edge of the semiconductor thin film and the boss structure; The semiconductor thin film is an arc-lobe-shaped semiconductor thin film, including four outer arc-shaped valves; The shape of the metal thin film matches the shape of the semiconductor thin film.

2. The micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect according to claim 1, wherein The metal thin film covers the top of the semiconductor thin film in the form of deposition.

3. A 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 combined with the peninsula-ended cross beam and the arc-lobe-shaped island is four short beams with a peninsula at the front end connected by an arc-lobe-shaped island at the center; 4. A 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 lateral strain-sensitive piezoresistive regions and two longitudinal strain-sensitive piezoresistive regions; the four ion implantation regions and the metal thin film are electrically connected to the external circuit through the metal electrode region.

5. A 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 regions are located at the connection of the fixed region around the semiconductor thin film and the arc-shaped short beams.

6. A 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 regions is W-shaped or dry-character-shaped.

7. A 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 regions include an ion implantation lightly doped region and an ion implantation heavily doped region.

8. A micro electric field sensor device based on the coupling of electrostatic force and piezoresistive effect according to claim 7, characterized in that, The areas of the ion implantation lightly doped region and the ion implantation 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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