A MEMS optical electric field sensor based on luminous flux detection

Abstract

The present invention discloses a MEMS optical electric field sensor based on luminous flux detection. A silicon microstructure grid layer and a glass chrome-plated grid layer are arranged up and down to form a sensitive structure. The lower silicon microstructure is connected to the underlying silicon structure by a spring, and the upper glass chrome-plated layer is fixed to the silicon microstructure by bonding. The upper structure is fixed and the lower silicon microstructure deforms with changes in the electric field. A light source is incident vertically from directly above and is received after passing through the two-layer structure. The deformation of the lower silicon microstructure causes the overlapping area of ​​the grid and the upper grid to change, thereby realizing a change in the received luminous flux. It can realize the measurement of electric field strength in a strong electromagnetic environment, and the preparation and packaging method is simple, easy to install and use, and low in cost. It can be applied to electric field measurement in multiple scenarios such as power system status monitoring and space electric field detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and in particular relates to a MEMS optical electric field sensor based on light flux detection. Background Art

[0002] Electric field measurement is of great significance in many scientific research and engineering fields, especially in power systems, electromagnetic compatibility, and microwave technology. For example, in electromagnetic science research, electric field measurement can be used as an effective means to verify the accuracy of electric field theory calculations, providing measurement values ​​for many difficult-to-calculate electric field environments. In the power industry, electric field measurement can be used for power system status monitoring, measuring the electric field distribution inside and outside electrical equipment, high voltage testing, and corona discharge phenomenon research. In electromagnetic compatibility research, electric field measurement can be used to detect external electromagnetic radiation and interference from electrical and electronic equipment, as well as to study the impact of environmental electric fields on the operation of electronic instruments. In microwave technology, it is necessary to measure the electric field around microwave transmitting and receiving equipment. In addition, space electric field sensors are also needed in nuclear physics and aerospace science and technology research. The detection of electric fields is of great significance to people's lives, production, and scientific research.

[0003] There are four main types of sensors currently circulating on the market:

[0004] (1) Field mill electric field sensor based on the principle of electric induction;

[0005] (2) Micro electric field sensor using MEMS technology;

[0006] (3) Fiber Bragg Grating Electric Field Sensor Based on Wavelength Modulation

[0007] (4) Optical electric field sensor based on phase demodulation.

[0008] Among them, the field grinding type DC electric field sensor has good performance and can measure the electric field of the transmission line, but the sensor is made of metal and is large in size. The metal structure has a large interference on the measured electric field, and it needs to be grounded, which is inconvenient to use; the most advanced MEMS-based electric field sensor is the torsional resonant electric field sensor proposed by the University of Science and Technology of China. The torsional resonant MEMS electric field sensor is small in size, has low power consumption, and is easy to mass produce. However, a small amount of charge will generate a large electric field between the sensing electrodes, so the problem of electric field distortion caused by the charge needs to be solved; the fiber Bragg grating electric field sensor is not easily affected by external electromagnetic interference, but because the photoelectric crystal is easily affected by factors such as temperature, it will interfere with the measured electric field; the rotational optical electric field sensor based on the basic principle of the Pockels effect eliminates the influence caused by space charge by rotation, but the sensor requires components such as fiber collimator, polarizer, electro-optical crystal, analyzer, etc., the structure is relatively complex, and it is inconvenient to use in practice. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned existing technologies and provide a MEMS optical electric field sensor based on luminous flux detection, which is used to solve the technical problems that similar sensors have complex installation methods, high costs, always have internal interference, and are difficult to adapt to complex industrial electrical measurement environments.

[0010] The present invention adopts the following technical solutions:

[0011] A MEMS optical electric field sensor based on luminous flux detection includes a glass chrome-plated layer, a grid-shaped metal chromium sputtered array on the surface of the glass chrome-plated layer, the glass chrome-plated layer is arranged on a device layer, and the device layer is arranged on a bottom silicon layer. An insulating layer is provided between the device layer and the bottom silicon layer. The grid-shaped metal chromium and the silicon microstructure grid on the device layer are arranged in an upper and lower manner to form a sensitive structure. The change in the received luminous flux is achieved by utilizing the change in the overlapping area of ​​the silicon microstructure grid and the grid-shaped metal chromium after deformation.

[0012] Specifically, the thickness of the grid-shaped metal chromium is 0.5 to 1 μm.

[0013] Specifically, the device layer is a suspended structure with a minimum precision of 20 μm.

[0014] Furthermore, the silicon microstructure grid is fixedly connected to the device layer via a spring, and the spring has a width of 40 μm±10% and a length of 280 μm±10%.

[0015] Furthermore, the thickness of the device layer is 50 μm±10%.

[0016] Specifically, the device layer includes an additional silicon structure, and the additional silicon structure is arranged on one side of the silicon microstructure grid.

[0017] Furthermore, the distance between the additional silicon structure and the silicon microstructure grid is less than or equal to 10 μm±10%.

[0018] Specifically, the number of pores in the grid-like metal chromium and silicon microstructure grids is 1600±10%, and they correspond one to one.

[0019] Furthermore, the alignment error between the grid-shaped metal chromium and the silicon microstructure grid is less than or equal to 5 μm.

[0020] Specifically, the glass chrome-plated layer and the device layer are connected by high-temperature bonding.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] The present invention discloses a MEMS optical electric field sensor based on light flux detection. Based on the principle of electrostatic induction, a grid-like structure is formed on glass by sputtering metal chromium. The grid is interlaced with the grid of the silicon microstructure below, so that light directly above cannot pass through the two layers of grids. Under the action of electrostatic force, the silicon microstructure below is deformed, resulting in pores at the intersection of the two layers of grids. The spatial electric field is measured by detecting the change in light flux. In order to ensure that the additional silicon structure on the leftmost side of the device layer plays a role in enhancing the local electric field, it is necessary to ensure that the additional silicon structure and the silicon microgrid are separated, but they must also be ensured to be in the same plane. Therefore, an insulating layer is provided between the device layer and the bottom silicon layer, and the two parts of the structure are connected by the insulating layer. The grid-like metal chromium on the glass chromium plating layer is formed by magnetron sputtering of chromium metal. The thin film prepared by magnetron sputtering has a fast film forming speed and high quality, which is conducive to improving the measurement accuracy of the electric field sensor. The selected materials are all semiconductor materials, which will not generate charge distortion themselves and avoid internal interference. The overall structure is small in size and can be applied to measure electric fields in multiple scenarios such as aerospace.

[0023] Furthermore, in order to ensure that the metal layer on the glass can block the passage of light, there are certain requirements for the thickness of the film to avoid the film layer being too thin and failing. If the film is too thick, the metal chromium will form a local electric field under the action of the electric field, interfering with the measurement accuracy. Therefore, the thickness of the grid-shaped metal chromium on the glass chrome plating layer is 0.5 to 1 μm.

[0024] Furthermore, in order to ensure the processing accuracy of the device layer, wet etching is selected. The wet etching equipment is simple, the etching rate is high, and the selectivity is high. Therefore, the device layer is wet-etched to form a suspended structure, and the minimum accuracy can reach 20μm.

[0025] Furthermore, to ensure that the spring deforms under the action of electrostatic force, the spring used to fix the silicon microstructure grid has a width of 40 μm ± 10% and a length of 280 μm ± 10%.

[0026] Furthermore, in order to ensure the deformation ability of the silicon microstructure, there are certain requirements for the thickness of the device layer. A device layer that is too thick will result in too small deformation, and a device layer that is too thin cannot guarantee the etching accuracy. Therefore, the thickness of the device layer is 50μm.

[0027] Furthermore, choosing silicon as the main material of the sensitive structure avoids internal interference. However, since silicon is a semiconductor material and is insensitive to electrostatic forces, the local electric field is enhanced by adding an additional silicon structure on the far left to increase the deformation.

[0028] Furthermore, to ensure that the additional silicon structure plays a role in enhancing the electric field, the distance between the additional silicon structure of the device layer and the silicon microstructure grid should not be too far. However, too close a distance will cause attraction, so the distance should not exceed 10μm±10%.

[0029] Furthermore, the number of pores opened in the upper and lower grids is 1,600. The more pores opened, the greater the change in the light flux passing through the upper and lower grids after the electrostatic force causes the silicon microstructure to deform, and the higher the measurement accuracy of the sensor. The number of pores depends on the area of ​​the sensor's sensitive structure and the processing technology.

[0030] Furthermore, in the absence of electrostatic force, light cannot pass through the upper and lower grid structures to reach the bottom. The alignment accuracy of the two grid structures affects the measurement accuracy of the sensor. Therefore, the alignment error between the grid-shaped metal chromium and the silicon microgrid structure of the device layer does not exceed 5μm.

[0031] Furthermore, the glass chrome-plated structure and the silicon microstructure are processed in two parts, so the glass chrome-plated layer and the device layer are connected together by high-temperature bonding, and the upper and lower layers are connected together by high-temperature bonding. The overall process uses MEMS technology, which can achieve mass production.

[0032] In summary, the present invention has the advantages of miniaturization, simple structure, easy packaging, passive detection and high precision.

[0033] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the oblique two-dimensional structure of the present invention;

[0035] Figure 2 It is a front view structural schematic diagram of the present invention;

[0036] Figure 3 It is a schematic diagram of the top view of the structure of the present invention;

[0037] Figure 4 It is a schematic diagram of the device layer oblique two-dimensional structure of the present invention.

[0038] Among them: 1. Glass chrome plating layer; 2. Grid-shaped metal chromium; 3. Device layer; 4. Insulation layer; 5. Bottom silicon layer; 6. Additional silicon structure; 7. Spring; 8. Silicon microstructure grid. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0040] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "one side," "one end," and "one side" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, in the description of the present invention, unless otherwise specified, "a plurality" means two or more.

[0041] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0042] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0043] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0044] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0045] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0046] The present invention provides a MEMS optical electric field sensor based on luminous flux detection. A silicon microstructure grid 8 and a glass chrome-plated layer 1 are arranged up and down to form a sensitive structure. The lower silicon microstructure grid 8 is connected to the bottom silicon layer 5 by a spring 7, and the upper glass chrome-plated layer 1 is fixed to the silicon microstructure grid 8 by bonding. The upper structure is fixed, and the lower silicon microstructure grid 8 deforms with changes in the electric field. Light source is incident vertically from directly above and is received after passing through the two-layer structure. The deformation of the lower silicon microstructure grid 8 causes the overlapping area of ​​the grid and the upper grid-shaped metal chromium 2 to change, thereby realizing a change in the received light flux. It can realize the measurement of electric field strength in a strong electromagnetic environment. The preparation and packaging method is simple, easy to install and use, and low in cost. It can be applied to electric field measurement in multiple scenarios such as power system status monitoring and space electric field detection.

[0047] See also Figure 1 The present invention provides a MEMS optical electric field sensor based on light flux detection, comprising a glass chrome-plated layer 1, a grid-shaped metal chrome 2, a device layer 3, an insulating layer 4, and a bottom silicon layer 5; the device layer 3 is arranged on the bottom silicon layer 5, the insulating layer 4 is located between the device layer 3 and the bottom silicon layer 5, the glass chrome-plated layer 1 is arranged on the device layer 3, and the grid-shaped metal chrome 2 is arranged on the surface of the glass chrome-plated layer 1.

[0048] The surface of the glass chrome-plated layer 1 is sputtered to form a grid-like metal chromium 2, which overlaps with the silicon microstructure grid 8 of the underlying silicon microstructure device layer 3, so that no light can pass directly above it when no deformation occurs.

[0049] The number of pores in the grid-shaped metal chromium 2 and the upper and lower grids of the device layer 3 is 1600±10%, and one-to-one correspondence is ensured.

[0050] The grid-shaped metal chromium 2 on the glass chromium plating layer 1 is attached to the glass chromium plating layer 1 by sputtering, and the thickness of the grid-shaped metal chromium 2 is 0.5 to 1 μm.

[0051] See also Figure 2 and Figure 3 There is an insulating layer 4 between the device layer 3 and the bottom silicon layer 5, wherein the device layer 3 and the bottom silicon layer 5 are both made of silicon material, which is a semiconductor. The insulating layer 4 is made of silicon dioxide material, which is an insulating material and has excellent insulation performance, which can ensure that the sensor can work stably in a strong electromagnetic environment.

[0052] The grid-shaped metal chromium 2 on the glass chromium plating layer 1 is formed by magnetron sputtering of chromium metal and is part of the overall structure of the sensitive element.

[0053] The glass chrome-plated layer 1 and the device layer 3 are connected together by high-temperature bonding.

[0054] The device layer 3 is the main part of the overall structure sensitive element, and is formed into a suspended structure by wet etching with a minimum accuracy of 20μm.

[0055] The thickness of the device layer 3 is 50 μm±10%.

[0056] The purpose of enhancing the local electric field is achieved by adding an additional silicon structure 6 on the leftmost side of the device layer 3, so that the silicon microstructure produces a greater deformation under the action of the electrostatic force.

[0057] See also Figure 4 A silicon microstructure grid 8 is provided on the device layer 3 corresponding to the grid-shaped metal chromium 2. The spacing between the additional silicon structure 6 of the device layer 3 and the silicon microstructure grid 8 does not exceed 10μm±10%. The spring 7 used to fix the silicon microstructure grid 8 has a width of 40μm±10% and a length of 280um±10%.

[0058] The alignment error between the grid-shaped metal chromium 2 and the silicon microstructure grid 8 of the device layer 3 does not exceed 5 μm.

[0059] The electric field sensor is mostly made of semiconductor materials, and there is no interference with the electric field in space. Its sensitivity to electric field measurement is over 120V / m.

[0060] The working principle of the MEMS optical electric field sensor based on light flux detection of the present invention is as follows:

[0061] The electric field affects the device layer 3 of the electric field sensor in the form of electrostatic force, causing it to deform slightly. The additional silicon structure 6 on the left side of the device layer 3 enhances the local electric field strength, causing the deformation of the silicon microgrid to increase. When the grid of the device layer 3 moves as a whole to the left, the light incident vertically from directly above passes through the glass chrome-plated layer 1, is partially shielded by the grid-shaped metal chromium 2, and then irradiates the silicon microstructure grid 8 of the device layer 3. The silicon microstructure grid 8 performs a secondary shielding on the light, so that only part of the light passes through the two layers of grids to reach the bottom. Finally, the electric field strength in space is calculated based on the size of the light flux reaching the bottom.

[0062] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0063] Place the electric field sensor in an environment with a strong electromagnetic field, align its overall plane with the direction of the electric field strength, and attach it to any plane to avoid minor interference such as noise; the receiving light source is led out through the optical fiber, and the hole is sealed with a sealing ring.

[0064] Compared with traditional field-grinding electric field sensors, the present invention has the advantages of miniaturization and micro-miniaturization, with the main structure size less than 1cm×1cm×0.2cm; compared with ordinary MEMS electric field sensors, no bias voltage is required, and a passive design is achieved, avoiding internal interference. The minimum detection field strength of the sensor can reach 342V / m; compared with traditional optical fiber electric field sensors, the light flux conversion method is used instead of the original electro-optical crystal solution, avoiding the detection error caused by the heating of the photoelectric crystal, and the sensor sensitivity can reach 50V / m.

[0065] To sum up, the present invention provides a MEMS optical electric field sensor based on luminous flux detection. The MEMS optical electric field sensor can realize the measurement of instantaneous electromagnetic pulses in a strong electromagnetic field environment. The preparation and packaging method is simple, easy to install and use, and has low cost. It can be used for electric field measurement in multiple scenarios such as power system status monitoring and space electric field detection.

[0066] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A MEMS optical electric field sensor based on light flux detection, characterized in that: The invention comprises a glass chrome-plated layer (1), a sputtered array of grid-shaped metal chrome (2) is arranged on the surface of the glass chrome-plated layer (1), the glass chrome-plated layer (1) is arranged on a device layer (3), the device layer (3) is arranged on a bottom silicon layer (5), an insulating layer (4) is arranged between the device layer (3) and the bottom silicon layer (5), the grid-shaped metal chrome (2) and the silicon microstructure grid (8) on the device layer (3) are arranged up and down to form a sensitive structure, and the change of the received light flux is achieved by utilizing the change of the overlapping area of ​​the silicon microstructure grid (8) and the grid-shaped metal chrome (2) after deformation.

2. The MEMS optical electric field sensor based on light flux detection according to claim 1, characterized in that: The thickness of the grid-shaped metal chromium (2) is 0.5 to 1 μm.

3. The MEMS optical electric field sensor based on light flux detection according to claim 1, characterized in that: The device layer (3) is a suspended structure with a minimum precision of 20 μm.

4. The MEMS optical electric field sensor based on light flux detection according to claim 3, characterized in that: The silicon microstructure grid (8) is fixedly connected to the device layer (3) via a spring (7), wherein the width of the spring (7) is 40 μm±10% and the length is 280 μm±10%.

5. The MEMS optical electric field sensor based on light flux detection according to claim 1 or 3, characterized in that: The thickness of the device layer (3) is 50 μm±10%.

6. The MEMS optical electric field sensor based on light flux detection according to claim 1, characterized in that: The device layer (3) includes an additional silicon structure (6) which is arranged on one side of the silicon microstructure grid (8).

7. The MEMS optical electric field sensor based on light flux detection according to claim 6, characterized in that: The spacing between the additional silicon structure (6) and the silicon microstructure grid (8) is less than or equal to 10 μm±10%.

8. The MEMS optical electric field sensor based on light flux detection according to claim 1, characterized in that: The number of pores in the grid-shaped metal chromium (2) and the silicon microstructure grid (8) is 1600±10%, and they correspond one to one.

9. The MEMS optical electric field sensor based on light flux detection according to claim 8, characterized in that: The alignment error between the grid-shaped metal chromium (2) and the silicon microstructure grid (8) is less than or equal to 5 μm.

10. The MEMS optical electric field sensor based on light flux detection according to claim 1, characterized in that: The glass chrome plating layer (1) and the device layer (3) are connected by high-temperature bonding.

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