Comb tooth capacitance type micro electro mechanical system angular acceleration sensor

Abstract

The invention provides a comb tooth capacitance type micro-electromechanical angular acceleration sensor, which comprises an upper substrate (1), a lower substrate (1), a control circuit (2), a sensitive structure layer (3), a conduction band layer (4) and a peripheral mounting shell (5), and is characterized in that at least four mass block fixing anchor points (7) are arranged on the same circumference or are arranged in a central symmetry manner; the flexible support beam (10) is used for hanging the mass block and transmitting an electric signal of the mass block (8); the mass block (8) is connected with the mass block anchor point (7) through the flexible supporting beam (10) and is used for sensing angular acceleration; the mass block (8) is provided with movable teeth of the detector (6) and the actuator (11), and the movable teeth are fixedly connected with the mass block (8) to move. According to the invention, the comb tooth capacitance detection actuator is adopted to realize the realization of the MEMS angular acceleration sensor, the device range and the sensitivity.

Description

Technical Field

[0001] This invention relates to the field of microelectromechanical systems (MEMS), specifically to a comb-tooth capacitive MEMS angular acceleration sensor, applicable to inertial navigation, attitude control, vehicle systems, and aerospace. Background Technology

[0002] With the rapid development of microelectromechanical systems (MEMS) technology, miniaturized, low-cost, and high-sensitivity sensors have been widely adopted in various applications. Currently, MEMS accelerometers mainly focus on linear acceleration detection, while their ability to detect angular acceleration is relatively weak. Traditional angular acceleration detection methods are mostly based on mechanical shafts or gyroscope structures, which are large in size, consume high power, and are difficult to integrate.

[0003] Existing MEMS angular acceleration sensors typically employ a seesaw structure, sensing angular acceleration by detecting the displacement of a mass block along a plane perpendicular to the structure under angular acceleration. However, because the angular acceleration sensitive structure layer and the electrical feedback structure are not on the same layer, there is a large alignment error, resulting in certain deficiencies in accuracy and poor product consistency.

[0004] Therefore, there is an urgent need for a new type of angular acceleration sensor. Summary of the Invention This invention provides a comb-tooth capacitive microelectromechanical angular acceleration sensor that can achieve high-sensitivity detection of angular acceleration on the MEMS scale, while also having the advantages of compact structure, low power consumption, easy integration, and high consistency. The first aspect of this invention provides a comb-tooth capacitive microelectromechanical angular acceleration sensor, comprising: upper and lower substrates 1, a control circuit 2, a sensitive structure layer 3, a conductive strip layer 4, and an outer mounting housing 5, wherein: The sensitive structural layer 3 includes: a comb-tooth capacitance detector 6, a mass block fixing anchor point 7, a mass block 8, a sealing bonding area 9, a flexible support beam 10, and a comb-tooth capacitance actuator 12. At least four mass block fixing anchor points 7 are fixed at both ends on the upper and lower base plates 1 and are arranged on the same circumference and centrally symmetrically. Mass blocks 8 are arranged in the circumference formed by the mass block fixing anchor points 7 and are suspended on the mass block fixing anchor points 7 by flexible support beams 10. The moving teeth of the comb-type capacitor detector 6 are connected to the periphery of the mass block 8. The fixed teeth of the comb-type capacitor detector 6 are fixed on the upper and lower substrates 1 and connected to the conductor layer 4 for sensing angular acceleration. The mass block 8 is equipped with the moving teeth of the comb-tooth capacitor actuator 12. The fixed teeth of the comb-tooth capacitor actuator 12 are fixed on the upper and lower substrates 1 and connected to the guide strip layer 4. It is used to receive control signals and execute feedback to pull the mass block 8 to the neutral position. A sealing bonding area 9 is provided around the comb-tooth capacitance detector 6, and the sealing bonding area 9 is fixed on the upper and lower substrates 1.

[0005] Optionally, the flexible support structure 10 is an n-shaped beam structure, a U-shaped beam structure, or an overlapping beam structure.

[0006] Optionally, the periphery of the mass block 8 is provided with a fan-shaped or rectangular structure, located between two adjacent mass block fixed anchor points 7, and suspended on the mass block fixed anchor points 7 by a flexible support beam 10.

[0007] Optionally, the fixed anchor point 7 of the mass block includes two axially symmetrical sub-anchor points, with the axis of symmetry passing through the centroid of the mass block 8; the sub-anchor points are respectively suspended from the mass block 8 by flexible support beams 10, and the direction of movement of the flexible support beams 10 is tangential to the centroid of the mass block 8.

[0008] Optionally, there are multiple fixed tooth electrodes and multiple moving tooth electrodes, which are arranged in a symmetrical staggered manner.

[0009] Optionally, the upper and lower substrates 1 are made of silicon-based materials and are processed using standard MEMS manufacturing processes, including photolithography, deposition, dry etching, and sacrificial layer release processes.

[0010] Optionally, the signal processing circuit 2 includes a differential bridge capacitance detection circuit, an amplifier, and a filter, used to convert the change in capacitance value detected by the fixed tooth into an angular acceleration electrical signal output. The signal processing circuit 2 also includes an ADC conversion module and a microprocessor for digitizing the detection signal and calculating the angular acceleration value.

[0011] Optionally, the conductive strip layer 4 is processed on the upper substrate 1 by a coating process to electrically connect the sensitive structure layer 3 and the control circuit 2; the angular accelerometer chip and the control circuit 2 are fixed in the mounting housing 5 by adhesive to connect with the application system.

[0012] Optionally, a sensitive structure layer 3 is disposed within the upper and lower substrates 1 to form a sensor chip; The outer casing 5 is used to fix the sensor chip and control circuit 2. The control circuit 2 is mounted on the outer mounting housing 5 and is electrically connected to the sensor chip.

[0013] The second aspect of the present invention provides a comb-type capacitive microelectromechanical angular acceleration sensor, which uses a central fixed anchor point 11 instead of the mass block fixed anchor point 7 in the angular acceleration sensor based on the comb-type capacitive structure as described in any one of the first aspects; The central anchor point 11 is set at the center of the mass block 8.

[0014] The beneficial effects of this invention are as follows: (I) Compared with existing angular accelerometer products, the present invention can adjust the range and accuracy of the present invention by changing the structural parameters of the flexible support beam, increasing or decreasing the number of anchor points, or changing the comb structure, thus forming a series of products.

[0015] (II) Compared with flexible angular accelerometers, the present invention improves product reliability and consistency by using MEMS process for deep etching and integral molding, and significantly reduces product power consumption and size.

[0016] (III) Compared to seesaw-type angular accelerometers, this invention, through the fine processing of a single-layer silicon wafer, ensures that the sensitive structure layer 3 and the electromechanical conversion structure are both arranged on the same silicon wafer. The accuracy is not affected by the alignment and bonding of multiple silicon wafers, significantly improving process consistency and yield. By adjusting the circuit, the active resistance damping system only provides feedback on vibrations near its resonant frequency, suppressing the vibration amplitude. This solves the problems of large comb area and high voltage required for damping systems that provide feedback across the entire frequency range at high vibration energy levels. The advantages of this invention are: it can effectively improve sensor production efficiency and product consistency, reduce process difficulty, increase the survival rate, and make it easy to design the range threshold according to requirements. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the external structure of a comb-tooth capacitive microelectromechanical angular acceleration sensor according to the present invention; Figure 2 This is a schematic diagram of the sensitive structure layer of a comb-tooth capacitive microelectromechanical angular acceleration sensor according to the present invention; Figure 3 Three structures for flexible supported beams; Explanation of reference numerals in the attached figures: 1. Upper and lower substrates, 2. Control circuit, 3. Sensitive structure layer, 4. Conductor layer, 5. Peripheral mounting housing, 6. Comb-type capacitor detector, 7. Peripheral anchor point, 8. Mass block, 9. Sealed bonding area, 10. Flexible support beam, 11. Center anchor point, 12. Comb-type capacitor actuator, an-type beam, bu-type beam, c-overlapping beam. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0020] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0021] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited from each other.

[0022] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] like Figure 1-3 As shown, this invention provides a comb-type capacitive microelectromechanical angular accelerometer (MEMS) sensor, which is sensitive to the external angular acceleration signal. The sensory structure layer 3 is fabricated on a silicon wafer, sealed and fixed by upper and lower substrates 1, electrically connected to the outside of the chip via a conductive strip layer 4, and finally controlled by a control circuit module 2 for feedback control of the mass block 8 and output of the angular acceleration signal. In this invention, the sensitive layer includes the mass block 8, a comb-type capacitive detector 6, a comb-type capacitive actuator 12, anchor points 7, and a flexible support structure 10, used for sensing and actuating feedback of the angular acceleration signal.

[0024] The technical solution adopted by this invention to solve its technical problem is: a comb-type capacitive microelectromechanical angular acceleration sensor, including a substrate 1, a mass block 8, a comb-type capacitive detector 6, a comb-type capacitive actuator 12, an anchor point 7, a flexible support structure 10, a conductive strip layer 4, and a control circuit 2. The fixed and movable comb-type electrodes are arranged alternately to form a comb-type capacitive structure; the movable comb-type electrode is rigidly connected to the mass block 8 and connected to the substrate 1 through a cantilever beam or flexible hinge structure, allowing the mass block 8 to deflect around a rotation axis under angular acceleration; when the sensor is subjected to angular acceleration, the mass block 8 undergoes angular displacement due to inertial force, driving the movable comb-type electrode to move, thereby changing its relative position with the fixed comb-type detector 6 electrode, causing a change in capacitance; after detecting the change in capacitance of the detector 6 by the control circuit 2, the comb-type actuator 12 applies an electromagnetic force to the mass block 8 to pull it to a neutral position; the magnitude of the angular acceleration can be calculated by the magnitude of the voltage applied by the actuator 12. The comb-type structure located on the silicon structure layer is integrally formed by deep etching using MEMS technology.

[0025] Preferably, the mass block is fixed at 8 anchor points 7 along the central symmetrical direction to constrain the movement in multiple directions, and at the same time, an anchor point 11 is arranged at the center to constrain the displacement of the mass block 8 in the Z direction.

[0026] Preferably, the mass block-supported flexible beam is used in pairs of U-shaped beams.

[0027] Preferably, the detection comb tooth structure is located on the outer ring, and the feedback comb tooth structure is located on the inner ring to improve detection sensitivity and reduce signal interference.

[0028] Preferably, the detection comb structure adopts a variable area comb structure to improve the detection linearity.

[0029] Preferably, the feedback comb teeth adopt a variable pitch comb tooth structure to improve the overall measuring range.

[0030] Preferably, the control circuit 2 is an ASIC circuit, and it is sealed in the same housing 5 as the angular accelerometer chip module and connected by gold wire bonding.

[0031] Preferably, the upper and lower substrates 1 are made of monocrystalline silicon, which results in better overall product temperature performance. Optionally, the present invention also includes a limiting mechanism that conforms to the configuration of the mass block structure 8 and limits its displacement along the sensitive direction.

[0032] Optionally, the flexible support beam 10 may be designed as an n-beam to improve the centering of the support structure 10.

[0033] Optionally, the detection comb teeth adopt a variable spacing design to improve detection sensitivity.

[0034] Optionally, the control circuit 2 adopts a discrete component circuit, with only the angular accelerometer chip module installed inside the mounting housing.

[0035] Optionally, the upper and lower substrates 1 are made of glass, which reduces the difficulty of the process and improves the bonding reliability.

[0036] Figure 1 A schematic diagram of a comb-type capacitive microelectromechanical angular acceleration sensor provided by the present invention includes a sensitive layer structure, upper and lower substrates 1, a conductive strip module, a control circuit 2 module, and a mounting housing 5, wherein: The sensitive layer structure is divided into five parts: anchor point 7, flexible support structure 10, comb tooth detector structure 6, comb tooth actuator structure 12, and mass block structure 8. The anchor point structure 7 is located in the middle of the mass block structure 8 and is connected by the flexible rib 5. The comb tooth detector structure 6 and the comb tooth actuator structure 12 have their moving teeth fixed in the middle of the mass block structure 8 and rigidly connected to the mass block 8; the two moving tooth structures are arranged symmetrically along the center, and the centroid of the set of all anchor point structures 7 coincides with the centroid of the mass block 8; The conductive strip module is electrically connected via the fixed tooth anchor point of the actuator 12 through bonding, and its electrical signal is led out of the sensitive structure layer 3 and connected to the control circuit 2 through gold wire bonding; The moving tooth part of the comb actuator structure 12 is fixed in the middle of the mass block structure 8 and is rigidly connected to the mass block 8; the two moving tooth structures are arranged symmetrically along the center, and the centroid of all anchor point structures coincides with the centroid of the mass block. The sensitive structural layer 3 is obtained by deep silicon etching process; The substrate 1 is manufactured using an all-silicon process; The optional upper and lower substrates 1 can be made of glass to reduce production costs and process complexity; The sensitive structure layer 3 is fabricated using a dry etching technique based on MEMS technology. Optionally, the range and threshold of the sensitive structural layer 3 can be adjusted by adjusting the stiffness of the supporting beam; Optionally, the range and threshold can be adjusted by the number of comb detectors 6 and comb actuators 12 and their distance from the center.

[0037] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A comb-tooth capacitive microelectromechanical angular acceleration sensor, characterized in that, include: The upper and lower substrates (1), control circuit (2), sensitive structure layer (3), conductive strip layer (4), and peripheral mounting housing (5) are as follows: The sensitive structure layer (3) includes: a comb-tooth capacitance detector (6), a mass block fixing anchor point (7), a mass block (8), a sealing bonding area (9), a flexible support beam (10), and a comb-tooth capacitance actuator (12). At least four mass block fixing anchor points (7) are fixed at both ends on the upper and lower base plates (1) and arranged on the same circumference and symmetrically arranged. The mass block (8) is arranged in the circumference formed by the mass block fixing anchor points (7) and is suspended on the mass block fixing anchor points (7) by a flexible support beam (10). The mass block (8) is connected to the moving teeth of the comb-type capacitance detector (6) on its periphery. The fixed teeth of the comb-type capacitance detector (6) are fixed on the upper and lower substrates (1) and connected to the conductor layer (4) for sensing angular acceleration. The moving teeth of the comb-tooth capacitor actuator (12) are provided inside the mass block (8). The fixed teeth of the comb-tooth capacitor actuator (12) are fixed on the upper and lower substrates (1) and connected to the guide strip layer (4) to receive control signals and execute feedback to pull the mass block (8) to the neutral position. A sealing bonding area (9) is provided around the comb-tooth capacitance detector (6), and the sealing bonding area (9) is fixed on the upper and lower substrates (1).

2. The angular acceleration sensor based on a comb-tooth capacitor structure according to claim 1, characterized in that, The flexible support structure 10 is an n-shaped beam structure, a U-shaped beam structure, or an overlapping beam structure.

3. The angular acceleration sensor based on a comb-tooth capacitor structure according to claim 1, characterized in that, The mass block (8) has a fan-shaped or rectangular structure on its periphery, located between two adjacent mass block fixed anchor points (7), and is suspended on the mass block fixed anchor points (7) by a flexible support beam (10).

4. The angular acceleration sensor based on a comb-type capacitor structure according to claim 1, characterized in that, The fixed anchor point (7) of the mass block includes two axially symmetrical sub-anchor points, the axis of symmetry passing through the centroid of the mass block (8); the sub-anchor points are suspended from the mass block (8) by flexible support beams (10), and the direction of motion of the flexible support beams (10) is tangential to the centroid of the mass block (8).

5. The angular acceleration sensor based on a comb-tooth capacitor structure according to claim 1, characterized in that, The number of fixed tooth electrodes and moving tooth electrodes are both multiple, and they are arranged in a symmetrical staggered manner.

6. The angular acceleration sensor based on a comb-tooth capacitor structure according to claim 1, characterized in that, The upper and lower substrates 1 are made of silicon-based materials and are processed using standard MEMS manufacturing processes, including photolithography, deposition, dry etching, and sacrificial layer release processes.

7. The angular acceleration sensor based on a comb-type capacitor structure according to claim 1, characterized in that, The signal processing circuit (2) includes a differential bridge capacitance detection circuit, an amplifier and a filter, used to convert the change in capacitance value detected by the fixed tooth into an angular acceleration electrical signal output; The signal processing circuit (2) also includes an ADC conversion module and a microprocessor for digitizing the detection signal and calculating the angular acceleration value.

8. The angular acceleration sensor based on a comb-type capacitor structure according to claim 1, characterized in that, The conductive strip layer (4) is processed on the upper substrate (1) by a coating process to electrically connect the sensitive structure layer (3) and the control circuit (2); the angular accelerometer chip and the control circuit (2) are fixed in the mounting housing (5) by adhesive to connect with the application system.

9. The angular acceleration sensor based on a comb-tooth capacitor structure according to claim 8, characterized in that, A sensitive structure layer (3) is disposed within the upper and lower substrates (1) to form a sensor chip; The outer casing (5) is used to fix the sensor chip and control circuit (2); The control circuit (2) is mounted on the outer mounting housing (5) and is electrically connected to the sensor chip.

10. A comb-tooth capacitive microelectromechanical angular acceleration sensor, characterized in that, The mass block fixed anchor point (7) in the angular acceleration sensor based on the comb-tooth capacitor structure as described in any one of claims 1-9 is replaced by a central fixed anchor point (11). The central anchor point (11) is set at the center of the mass block (8).

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