A MEMS gyroscope and its manufacturing method

Abstract

The present invention discloses a MEMS gyroscope and a preparation method thereof. The gyroscope comprises: electrodes comprising a plurality of inner electrodes, a plurality of inter-ring electrodes and a plurality of outer electrodes; at least two vibration rings surround the plurality of inner electrodes; a plurality of inter-ring electrodes are arranged between adjacent vibration rings, and the plurality of inter-ring electrodes are evenly arranged along the circumference of the vibration ring; a plurality of outer electrodes are arranged between the vibration ring and the anchoring area, and the plurality of outer electrodes are arranged in sequence along the circumference of the vibration ring; a plurality of connecting beams are arranged between the anchoring area and the outer electrodes, and the plurality of connecting beams are arranged in sequence along the circumference of the vibration ring; the anchoring area, the inter-ring electrodes and the inner electrodes are fixedly arranged on a substrate, and a cavity is provided between the connecting beam, the vibration ring and the outer electrode and the substrate; there are gaps between the connecting beam and the anchoring area, between the connecting beam and the outer electrode, between the outer electrode and the vibration ring, between the vibration ring and the inter-ring electrodes, between adjacent inter-ring electrodes, and between the vibration ring and the inner electrode. The present invention improves the sensitivity of the gyroscope.

Description

Technical Field

[0001] The present invention relates to the technical field of gyroscopes, and in particular to a MEMS gyroscope and a preparation method thereof. Background Art

[0002] As a key sensor, gyroscopes play an important role in many fields. By measuring angular velocity and direction, they provide accurate attitude and position data to support efficient and reliable operation of various applications. Gyroscopes are mainly divided into mechanical gyroscopes and micro-electro-mechanical system (MEMS) gyroscopes. MEMS gyroscopes are widely used in aerospace, autonomous driving, consumer electronics and other fields due to their miniaturization, low cost and high reliability.

[0003] Most MEMS gyroscopes are vibratory gyroscopes, whose basic working principle is based on the energy transfer caused by the Coriolis force between two vibration modes of the vibrating element. According to the structure of the vibrating element, vibratory gyroscopes can be mainly divided into linear vibration type and vibratory ring type. Vibratory ring gyroscopes have the following advantages over linear vibration gyroscopes: Since its mass is evenly distributed on the axisymmetric structure, it can effectively resist external shocks. The sensing mode and the driving mode have approximately the same frequency, so its sensitivity can be increased in proportion to the quality factor (Q factor). In addition, since the structure is uniformly affected by the thermal environment, the vibratory ring gyroscope is less sensitive to temperature. The frequency mismatch caused by the asymmetric distribution of mass and stiffness can be electrically compensated by the balancing electrode.

[0004] Existing vibrating ring gyroscopes are mainly divided into three driving modes: electrostatic drive, electromagnetic drive and piezoelectric drive. Although the existing electrostatic ring gyroscopes are superior to other types of gyroscopes in terms of simple design, sensitivity and low power consumption, their sensitivity still cannot meet application requirements. Summary of the invention

[0005] The invention provides a MEMS gyroscope and a preparation method thereof, so as to improve the sensitivity of the gyroscope.

[0006] According to one aspect of the present invention, a MEMS gyroscope is provided, comprising: a substrate and a device layer arranged on one side of the substrate; the device layer comprises an anchoring region, an electrode, a plurality of connecting beams and at least two vibration rings; the anchoring region surrounds the electrode, the plurality of connecting beams and the at least two vibration rings.

[0007] The electrodes include a plurality of inner electrodes, a plurality of inter-ring electrodes and a plurality of outer electrodes; the at least two vibration rings surround the plurality of inner electrodes, and the plurality of inner electrodes are evenly arranged around the center of the gyroscope; the plurality of inter-ring electrodes are arranged between adjacent vibration rings, and the plurality of inter-ring electrodes are evenly arranged along the circumference of the vibration ring; the plurality of outer electrodes are arranged between the vibration ring and the anchoring area, and the plurality of outer electrodes are arranged in sequence along the circumference of the vibration ring; the plurality of connecting beams are arranged between the anchoring area and the outer electrodes, and the plurality of connecting beams are arranged in sequence along the circumference of the vibration ring.

[0008] The anchoring area, the inter-ring electrode and the inner electrode are fixedly arranged on the substrate, and a cavity is provided between the connecting beam, the vibration ring and the outer electrode and the substrate; there are gaps between the connecting beam and the anchoring area, between the connecting beam and the outer electrode, between the outer electrode and the vibration ring, between the vibration ring and the inter-ring electrode, between adjacent inter-ring electrodes, and between the vibration ring and the inner electrode; adjacent vibration rings are connected by a plurality of straight beams, which are arranged in sequence along the circumference of the vibration ring, and both ends of each straight beam are connected to two adjacent vibration rings; one end of each connecting beam is connected to the vibration ring, and the other end is connected to the anchoring area; one end of each outer electrode is connected to the anchoring area.

[0009] Optionally, a plurality of first inter-ring electrodes and a plurality of second inter-ring electrodes are arranged between each two adjacent vibration rings; the plurality of first inter-ring electrodes are arranged in sequence along the circumference of the vibration ring, and the plurality of second inter-ring electrodes are arranged in sequence along the circumference of the vibration ring; the second inter-ring electrodes are arranged on a side of the first inter-ring electrodes adjacent to the inner electrode.

[0010] Optionally, there is a gap between adjacent inner electrodes, and the straight beam is arranged opposite to the gap; at least one of the first inter-ring electrodes and at least one of the second inter-ring electrodes are arranged between every two straight beams.

[0011] Along the radial direction of the vibration ring, each of the inner electrodes is correspondingly provided with at least one outer electrode and at least one connecting beam.

[0012] Optionally, the straight beams and the gaps between two adjacent vibration rings are arranged in one-to-one correspondence, and a first inter-ring electrode and a second inter-ring electrode are arranged between every two straight beams.

[0013] Two outer electrodes and two connecting beams are arranged corresponding to each inner electrode. The two outer electrodes are symmetrical with respect to the symmetry axis of the corresponding inner electrode, and the two connecting beams are corresponding with respect to the symmetry axis of the corresponding inner electrode.

[0014] Optionally, the device layer is centrally symmetrical, and the device layer is symmetrical relative to a gap between any two inner electrodes.

[0015] Optionally, the connecting beam includes a main body, a first connecting portion and a second connecting portion; the first connecting portion and the second connecting portion extend in a radial direction of the vibration ring.

[0016] One end of the first connection portion is connected to the anchoring area, and the other end is connected to the first end of the main body.

[0017] One end of the second connection portion is connected to the second end of the main body, and the other end of the second connection portion is connected to the vibration ring.

[0018] The main body includes at least one folded strip structure, which extends along the circumference of the vibration ring. The folded strip structure includes a first section, a second section and a third section. The first section, the second section and the third section are connected in sequence, and the first section and the third section extend along the circumference of the vibration ring.

[0019] Optionally, the shape of the first segment is at least one of a straight line, a broken line, a wavy line and a square wave; and / or the shape of the third segment is at least one of a straight line, a broken line, a wavy line and a square wave.

[0020] Optionally, the edge of the anchoring region adjacent to the outer electrode is polygonal or circular; the inter-ring electrode is arc-shaped, and the inner electrode is fan-shaped.

[0021] According to another aspect of the present invention, there is provided a method for preparing a MEMS gyroscope, which is used to form the MEMS gyroscope described in any embodiment of the present invention, and the method comprises: patterning a first surface of a device material layer to form a cavity; forming a barrier layer at the bottom of the cavity; bonding the first surface of the device material layer to a substrate; patterning a second surface of the device material layer to form a device layer having an anchoring region, an electrode, a plurality of connecting beams and at least two vibration rings; and removing the barrier layer.

[0022] Optionally, the second surface of the device material layer is patterned to form a device layer having an anchoring area, an electrode, a plurality of connecting beams and at least two vibration rings, including: thinning the device material layer; forming a pad on a surface of the thinned device material layer away from the substrate; and etching the thinned device material layer to form a device layer having an anchoring area, an electrode, a plurality of connecting beams and at least two vibration rings.

[0023] The device layer of the MEMS gyroscope of the embodiment of the present invention comprises an anchoring region, an electrode, a plurality of connecting beams and at least two vibration rings; the anchoring region surrounds the electrode, the plurality of connecting beams and the at least two vibration rings; the electrode comprises a plurality of inner electrodes, a plurality of inter-ring electrodes and a plurality of outer electrodes; at least two vibration rings surround the plurality of inner electrodes, and the plurality of inner electrodes are evenly arranged around the center of the gyroscope; the plurality of inter-ring electrodes are arranged between adjacent vibration rings, and the plurality of inter-ring electrodes are evenly arranged along the circumference of the vibration ring; the plurality of outer electrodes are arranged between the vibration ring and the anchoring region, and the plurality of outer electrodes are arranged along the The circumference of the vibration ring is arranged in sequence; multiple connecting beams are arranged between the anchoring area and the outer electrode, and the multiple connecting beams are arranged in sequence along the circumference of the vibration ring; there are gaps between the connecting beam and the anchoring area, between the connecting beam and the outer electrode, between the outer electrode and the vibration ring, between the vibration ring and the inter-ring electrode, between adjacent inter-ring electrodes, and between the vibration ring and the inner electrode; capacitors are formed between the outer electrode and the vibration ring, between the inter-ring electrode and the adjacent vibration ring, and between the inner electrode and the vibration ring, which increases the capacitance by at least four times compared with the traditional unilateral detection, thereby improving the detection sensitivity. In addition, the MEMS gyroscope implemented by the present invention can adopt differential capacitance detection, which can effectively reduce the influence of temperature changes on the measurement results, reduce the influence of noise in the circuit, and improve the accuracy of measurement.

[0024] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 It is a top view of a MEMS gyroscope provided by an embodiment of the present invention.

[0027] Figure 2 yes Figure 1 Cross-sectional view of the MEMS gyroscope along section line AA'.

[0028] Figure 3 yes Figure 1 Cross-sectional view of the MEMS gyroscope along section line BB'.

[0029] Figure 4 It is a schematic diagram of a driving mode simulation of a MEMS gyroscope provided by the present invention.

[0030] Figure 5It is a schematic diagram of detection mode simulation of a MEMS gyroscope provided by the present invention.

[0031] Figure 6 It is a schematic diagram of the capacitance formed between the local oscillation ring and the local electrode provided by the present invention.

[0032] Figure 7 It is a cross-sectional schematic diagram of another MEMS gyroscope provided by an embodiment of the present invention.

[0033] Figure 8 It is a schematic diagram of a connecting beam provided in an embodiment of the present invention.

[0034] Fig. 9 It is a schematic diagram of another connecting beam provided by an embodiment of the present invention.

[0035] Fig.10 It is a schematic diagram of another connecting beam provided by an embodiment of the present invention.

[0036] Fig.11 It is a flow chart of a method for preparing a MEMS gyroscope provided by an embodiment of the present invention.

[0037] Fig.12 is a schematic diagram of the device material layers after the cavity is formed.

[0038] Fig.13 It is a schematic diagram after forming a barrier layer.

[0039] Fig.14 It is a schematic diagram after the device material layer is bonded to the substrate.

[0040] Fig.15 This is a schematic diagram after the pad is formed.

[0041] Fig.16 It is a schematic diagram after forming the device layer and removing the barrier layer. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme 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 only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0043] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0044] An embodiment of the present invention provides a MEMS gyroscope. Figure 1 is a top view of a MEMS gyroscope provided by an embodiment of the present invention, Figure 2 yes Figure 1 The cross-sectional view of the MEMS gyroscope along the section line AA', Figure 3 yes Figure 1 Cross-sectional view of the MEMS gyroscope along section line BB'. Figure 1-Figure 3 The MEMS gyroscope includes: a substrate 10 and a device layer 20 arranged on one side of the substrate 10; the device layer 20 includes an anchoring area 21, an electrode 30, a plurality of connecting beams 22 and at least two vibration rings 23; the anchoring area 21 surrounds the electrode 30, the plurality of connecting beams 22 and the at least two vibration rings 23.

[0045] The electrode 30 includes a plurality of inner electrodes 33, a plurality of inter-ring electrodes 32 and a plurality of outer electrodes 31; at least two vibration rings 23 surround the plurality of inner electrodes 33, and the plurality of inner electrodes 33 are evenly arranged around the center of the gyroscope; a plurality of inter-ring electrodes 32 are arranged between adjacent vibration rings 23, and the plurality of inter-ring electrodes 32 are evenly arranged along the circumference of the vibration ring 23; a plurality of outer electrodes 31 are arranged between the vibration ring 23 and the anchoring area 21, and the plurality of outer electrodes 31 are arranged in sequence along the circumference of the vibration ring 23; a plurality of connecting beams 22 are arranged between the anchoring area 21 and the outer electrodes 31, and the plurality of connecting beams 22 are arranged in sequence along the circumference of the vibration ring 23.

[0046] Adjacent vibration rings 23 are connected by a plurality of straight beams 40, and the plurality of straight beams 40 are arranged in sequence along the circumference of the vibration ring 23, and the two ends of each straight beam 40 are connected to two adjacent vibration rings; the anchoring area 21, the inter-ring electrode 32 and the inner electrode 33 are fixedly arranged on the substrate 10, and a cavity 41 is provided between the connecting beam 22, the vibration ring 23, the outer electrode 31 and the substrate 10; there are gaps 42 between the connecting beam 22 and the anchoring area 21, between the connecting beam 22 and the outer electrode 31, between the outer electrode 31 and the vibration ring 23, between the vibration ring 23 and the inter-ring electrode 32, between adjacent inter-ring electrodes 32, and between the vibration ring 23 and the inner electrode 33.

[0047] One end of each connection beam 22 is connected to the vibration ring 23 , and the other end is connected to the anchoring area 21 ; one end of each external electrode 31 is connected to the anchoring area 21 .

[0048] The device layer 20 is etched to form a cavity 41 and a gap 42, and the cavity 41 and the gap 42 divide the device layer 20 into an anchoring area 21, a connecting beam 22, a vibration ring 23, and an electrode 30. The cavity 41 is located in the lower half of the device layer 20 (i.e., located between the connecting beam 22, the vibration ring 23, the external electrode 31 and the substrate 10), and the gap 42 runs through the upper half of the device layer 20 (i.e., the gap 42 is located between the connecting beam 22 and the external electrode 31, between the external electrode 31 and the vibration ring 23, between the vibration ring 23 and the inter-ring electrode 32, between adjacent inter-ring electrodes 32, and between the vibration ring 23 and the inner electrode 33). The area where the vertical projections of the cavity 41 and the gap 42 overlap on the substrate 10 completely runs through the device layer 20. The vertical projections of the connecting beam 22, the vibration ring 23, and the external electrode 31 on the substrate 10 are located in the cavity 41.

[0049] The vibration ring 23 is connected to the anchoring area 21 through a connecting beam 22. The vibration ring 23 is circular. At least two vibration rings 23 are arranged in sequence along the radial direction of the vibration ring 23, and the at least two vibration rings 23 can be two vibration rings 23, three vibration rings 23 or four vibration rings 23, etc. Exemplarily, the at least two vibration rings 23 include a first vibration ring 231 and a second vibration ring 232, the diameter of the second vibration ring 232 is smaller than that of the first vibration ring 231, and the first vibration ring 231 and the second vibration ring 232 are connected by a straight beam 40. The inter-ring electrode 32 is between the first vibration ring 231 and the second vibration ring 232, and the inter-ring electrode 32 can include a first inter-ring electrode 321 close to the first vibration ring 231 and a second inter-ring electrode 322 close to the second vibration ring 232.

[0050] The inner electrode 33 is fan-shaped and distributed along the circumference of the vibration ring 23. The number can be an integer multiple of 8 or an integer multiple of 12. The inter-ring electrodes 32 are arc-shaped and distributed along the circumference of the vibration ring 23. The number can be an integer multiple of 8 or an integer multiple of 12. The connecting beam 22 can include a folded strip structure. A plurality of connecting beams 22 are symmetrically arranged and distributed along the circumference of the vibration ring 23. The number of connecting beams 22 can be an integer multiple of 8 or an integer multiple of 12. The angle of the symmetry axis of the plurality of connecting beams 22 is 45° or 30°. The connecting beam 22 with a folded strip structure can provide displacement space for the deformation of the vibration ring 23.

[0051] Figure 4 is a schematic diagram of a driving mode simulation of a MEMS gyroscope provided by the present invention, Figure 5 This is a schematic diagram of a detection mode simulation of a MEMS gyroscope provided by the present invention, referring to Figure 4When alternating current is applied to the electrodes and vibration ring in the X or Y direction, the vibration ring will stretch or shrink to the maximum along the X or Y direction under the action of electrostatic force, and the vibration direction of the driving mode is along the X or Y direction. When the MEMS gyroscope rotates circumferentially, the vibration ring of the MEMS gyroscope will generate Coriolis force, and the direction of this force is perpendicular to the vibration direction. This force will cause the vibration mode of the vibration ring to change, causing the vibration ring to vibrate in a new mode, which is the detection mode. When the MEMS gyroscope works in the n=2 mode, the vibration direction of the detection mode vibration ring is 45° to the vibration direction of the driving mode vibration ring, refer to Figure 5 , the vibrating ring stretches or contracts in a direction 45° to the Y direction. The vibration form of the n=2 mode is relatively simple and easy to detect, and is often used in the basic working mode of the vibrating ring gyroscope. It has good sensitivity and stability in angular velocity detection. In an embodiment of the present invention, the frequency of the driving mode is 14.441kHz, the frequency of the detection mode is 14.444kHz, and the frequency resolution is only 3Hz. The close frequencies of the driving mode and the detection mode can maximize the response to the Coriolis effect, thereby enhancing the sensitivity and measurement accuracy of the gyroscope. When the MEMS gyroscope operates in the n=3 mode, the vibration direction of the detection mode is 30° to the vibration direction of the driving mode. The n=3 mode is generally used for higher precision measurements or specific research applications due to its higher characteristic frequency and more complex vibration form.

[0052] When the MEMS gyroscope is working, a driving signal is applied to the vibrating ring and the outer electrode, or to the vibrating ring, the outer electrode and the inner electrode. When the MEMS gyroscope does not rotate circumferentially, the vibrating ring stretches and contracts in the direction of the electrode to which the driving signal is applied. When the MEMS gyroscope rotates circumferentially, the stretching and contraction direction of the vibrating ring is 45° (n=2 mode) or 30° (n=3 mode) compared to the stretching and contraction direction when there is no circumferential rotation. The circumferential angular velocity is detected by detecting the change in capacitance between the vibrating ring and the electrode.

[0053] Figure 6 is a schematic diagram of a capacitor formed between a local vibration ring and a local electrode provided by the present invention, with reference to Figure 3 and Figure 6 , arc-shaped capacitors are formed between the first vibration ring 231 and the outer electrode 31, the first inter-ring electrode 321 and the first vibration ring 231, the second vibration ring 232 and the second inter-ring electrode 322, and the inner electrode 33 and the second vibration ring 232. The capacitance calculation formula is: .

[0054] C is the capacitance, the unit is Farad (F). 0 is the vacuum permittivity, which is the electrical constant. ris the relative dielectric constant, which depends on the dielectric material between the two plates. A is the area of ​​the parallel plates. Here, it is the product of the length L and the height H of the arc electrode. d is the distance between the two plates, which is the spacing between the vibration ring 23 and the electrode. For an electrostatic MEMS gyroscope of a certain size, the increase in its length L and height H is limited, and the reduction in spacing d is subject to process limitations. In a conventional electrostatic MEMS gyroscope, a capacitor is formed only between the vibration ring 23 and the electrode on one side (the electrode on one side of the vibration ring 23). At this time, the change in capacitance is small and the detection sensitivity is low. The embodiment of the present invention designs an outer electrode 31, an inter-ring electrode 32, and an inner electrode 33. Capacitors are formed between the outer electrode 31 and the vibration ring 23, between the inter-ring electrode 32 and the adjacent vibration ring 23, and between the inner electrode 33 and the vibration ring 23. Compared with the capacitance of conventional unilateral detection, the capacitance is increased by four times, which greatly increases the detection sensitivity.

[0055] Figure 7 is a cross-sectional schematic diagram of another MEMS gyroscope provided by an embodiment of the present invention, Figure 7 is a schematic diagram of the vibration ring 23 after being stretched, Figure 7 The middle dotted frame is the position of the vibration ring 23 when it is not compressed and stretched, that is, the original position of the vibration ring 23. Figure 7 When the vibration ring 23 is stretched, the distance between the first vibration ring 231 and the outer electrode 31 decreases, and the distance between the first vibration ring 231 and the first inter-ring electrode 321 increases. The capacitance between the first vibration ring 231 and the outer electrode 31 increases, and the capacitance between the first vibration ring 231 and the first inter-ring electrode 321 decreases, and the two capacitors constitute a differential capacitance. The distance between the second vibration ring 232 and the inner electrode 33 increases, and the distance between the second vibration ring 232 and the second inter-ring electrode 322 decreases. The capacitance between the second vibration ring 232 and the inner electrode 33 increases, and the capacitance between the second vibration ring 232 and the second inter-ring electrode 322 decreases, and the two capacitors constitute a differential capacitance. The MEMS gyroscope of the embodiment of the present invention can adopt differential capacitance detection. The differential capacitance technology has high sensitivity and accuracy and can detect small mechanical changes. Through differential measurement, the influence of temperature changes on the measurement results can be effectively reduced, and the accuracy of the measurement can be improved. At the same time, the increase in capacitance will reduce the noise in the circuit.

[0056] The device layer 20 of the MEMS gyroscope of the embodiment of the present invention includes an anchoring region 21, an electrode 30, a plurality of connecting beams 22 and at least two vibration rings 23; the anchoring region 21 surrounds the electrode 30, the plurality of connecting beams 22 and the at least two vibration rings 23; the electrode 30 includes a plurality of inner electrodes 33, a plurality of inter-ring electrodes 32 and a plurality of outer electrodes 31; at least two vibration rings 23 surround the plurality of inner electrodes 33, and the plurality of inner electrodes 33 are evenly arranged around the center of the gyroscope; the plurality of inter-ring electrodes 32 are arranged between adjacent vibration rings 23, and the plurality of inter-ring electrodes 32 are evenly arranged along the circumference of the vibration ring 23; the plurality of outer electrodes 31 are arranged between the vibration ring 23 and the anchoring region 21, and the plurality of outer electrodes 31 are arranged along the The circumference of the vibration ring 23 is arranged in sequence; a plurality of connecting beams 22 are arranged between the anchoring area 21 and the outer electrode 31, and the plurality of connecting beams 22 are arranged in sequence along the circumference of the vibration ring 23; there are gaps 42 between the connecting beams 22 and the anchoring area 21, between the connecting beams 22 and the outer electrode 31, between the outer electrode 31 and the vibration ring 23, between the vibration ring 23 and the inter-ring electrode 32, between adjacent inter-ring electrodes 32, and between the vibration ring 23 and the inner electrode 33; capacitors are formed between the outer electrode 31 and the vibration ring 23, between the inter-ring electrode 32 and the adjacent vibration ring 23, and between the inner electrode 33 and the vibration ring 23, which are at least four times higher than the capacitance of the traditional unilateral detection, thereby improving the detection sensitivity. In addition, the MEMS gyroscope implemented by the present invention can adopt differential capacitance detection, which can effectively reduce the influence of temperature changes on the measurement results, reduce the influence of noise in the circuit, and improve the accuracy of the measurement.

[0057] Optional, reference Figure 1-Figure 3 A plurality of first inter-ring electrodes 321 and a plurality of second inter-ring electrodes 322 are arranged between each two adjacent vibration rings 23 . The plurality of first inter-ring electrodes 321 are arranged in sequence along the circumference of the vibration ring 23 . The plurality of second inter-ring electrodes 322 are arranged in sequence along the circumference of the vibration ring 23 . The second inter-ring electrodes 322 are arranged on one side of the first inter-ring electrodes 321 adjacent to the inner electrode 33 .

[0058] The first inter-ring electrodes 321 and the second inter-ring electrodes 322 are arranged along the radial direction of the vibration ring 23. Each inner electrode 33 may be provided with one, two or more first inter-ring electrodes 321, and each inner electrode 33 may be provided with one, two or more second inter-ring electrodes 322. A capacitor may be formed between the first inter-ring electrodes 321 and the vibration ring 23, a capacitor may be formed between the second inter-ring electrodes 322 and the vibration ring 23, and a capacitor may be formed between the first inter-ring electrodes 321 and the second inter-ring electrodes 322, which may further increase the detection capacitance and further improve the detection sensitivity of the gyroscope.

[0059] Optionally, there is a gap between adjacent inner electrodes 33 , and the straight beams 40 are arranged opposite to the gap; at least one first inter-ring electrode 321 and at least one second inter-ring electrode 322 are arranged between every two straight beams 40 .

[0060] Along the radial direction of the vibration ring 23 , each inner electrode 33 is correspondingly provided with at least one outer electrode 31 and at least one connecting beam 22 .

[0061] Specifically, when the gyroscope works in the n=2 mode, the number of the inner electrodes 33 is an integer multiple of 8, and the number of the first inter-ring electrodes 321 and the number of the second inter-ring electrodes 322 between two adjacent vibration rings 23 can both be an integer multiple of 8. When the gyroscope works in the n=3 mode, the number of the inner electrodes 33 is an integer multiple of 12, and the number of the first inter-ring electrodes 321 and the number of the second inter-ring electrodes 322 between two adjacent vibration rings 23 can both be an integer multiple of 12. The number of the first inter-ring electrodes 321 and the number of the second inter-ring electrodes 322 between two adjacent vibration rings 23 can be the same as the number of the inner electrodes 33. The number of the straight beams 40 between two adjacent vibration rings 23 can be less than or equal to the number of the gaps between the inner electrodes 33. Each inner electrode 33 can correspond to one outer electrode 31 and one connecting beam 22, and each inner electrode 33 can also correspond to two or more outer electrodes 31 and two or more connecting beams 22. When the inner electrode 33 corresponds to two or more outer electrodes 31 , the two or more outer electrodes 31 can be arranged in sequence along the circumference of the vibration ring 23 ; when the inner electrode 33 corresponds to two or more connecting beams 22 , the two or more connecting beams 22 can be arranged in sequence along the circumference of the vibration ring 23 .

[0062] Since the vibration ring 23 between the straight beams 40 is more likely to deform, the straight beams 40 are arranged opposite to the gaps, so that the vibration ring 23 between the straight beams 40 is arranged opposite to the inner electrode 33, so that when the driving signal is applied to the vibration ring 23 and the electrode, the deformation of the vibration ring 23 opposite to the electrode is larger, and the capacitance changes more, further improving the detection sensitivity. At least one first inter-ring electrode 321 and at least one second inter-ring electrode 322 are arranged between every two straight beams 40; along the radial direction of the vibration ring 23, each inner electrode 33 is correspondingly provided with at least one outer electrode 31 and at least one connecting beam 22, so that along the radial direction of the vibration ring 23, the inner electrode 33, the vibration ring 23, the inter-ring electrode 32, the vibration ring 23 and the outer electrode 31 are arranged in sequence, ensuring that each position along the circumference of the vibration ring 23 has a large capacitance, further improving the detection sensitivity.

[0063] Optionally, the straight beams 40 between two adjacent vibration rings 23 are arranged in one-to-one correspondence with the gaps, and a first inter-ring electrode 321 and a second inter-ring electrode 322 are arranged between every two straight beams 40 .

[0064] Two outer electrodes 31 and two connecting beams 22 are arranged corresponding to each inner electrode 33, the two outer electrodes 31 are symmetrical with respect to the symmetry axis of the corresponding inner electrode 33, and the two connecting beams 22 are arranged corresponding to the symmetry axis of the corresponding inner electrode 33. This arrangement can increase the detection capacitance of the MEMS gyroscope and improve the detection sensitivity while reducing the structural complexity, manufacturing process difficulty and process cost.

[0065] Specifically, there are multiple straight beams 40 between every two adjacent vibration rings 23, and the multiple straight beams 40 are arranged in a one-to-one correspondence with the gaps between the internal electrodes 33, that is, the straight beams 40 divide the vibration rings 23 into multiple sub-regions, and the multiple sub-regions correspond to the internal electrodes 33 one-to-one.

[0066] Optionally, the device layer 20 is centrally symmetrical, and the device layer 20 is symmetrical relative to the gap between any two inner electrodes 33. This arrangement ensures that the vibration characteristics of the vibration ring 23 in all directions are consistent, thereby improving the detection accuracy.

[0067] Figure 8 is a schematic diagram of a connecting beam provided by an embodiment of the present invention, Fig. 9 is a schematic diagram of another connecting beam provided by an embodiment of the present invention, Fig.10 is a schematic diagram of another connecting beam provided by an embodiment of the present invention. Figure 2 , Figure 8-Figure 10 The connecting beam 22 includes a main body portion 223 , a first connecting portion 221 and a second connecting portion 222 ; the first connecting portion 221 and the second connecting portion 222 extend along the radial direction of the vibration ring 23 .

[0068] One end of the first connection portion 221 is connected to the anchoring area 21 , and the other end is connected to the first end of the main body portion 223 .

[0069] One end of the second connection portion 222 is connected to the second end of the main body 223 , and the other end is connected to the vibration ring 23 .

[0070] The main body 223 includes at least one folded strip structure 70, which extends along the circumference of the vibration ring 23. The folded strip structure 70 includes a first section 71, a second section 72 and a third section 73. The first section 71, the second section 72 and the third section 73 are connected in sequence, and the first section 71 and the third section 73 extend along the circumference of the vibration ring 23.

[0071] Specifically, when the main body 223 includes two or more folding strip structures 70, the two or more folding strip structures 70 are connected to each other, for example, the first segment 71 of the first folding strip structure is connected to the second connecting portion 222, the third segment 73 of the first folding strip structure is connected to the first segment 71 of the second folding strip structure, the third segment 73 of the second folding strip structure is connected to the first segment 71 of the next folding strip structure, or is connected to the first connecting portion 221.

[0072] The main body 223 includes at least one folded strip structure 70, so that the connecting beam 22 is more easily deformed, the vibration ring 23 is more easily stretched or compressed, the deformation of the vibration ring 23 is increased, the detection capacitance is increased, and the detection sensitivity of the gyroscope is improved.

[0073] Optionally, the shape of the first section 71 is at least one of a straight line, a broken line, a wavy line and a square wave; and / or the shape of the third section 73 is at least one of a straight line, a broken line, a wavy line and a square wave.

[0074] This arrangement makes it easier for the connection beam 22 to deform and the vibration ring 23 to stretch or compress, thereby further improving the detection sensitivity of the gyroscope.

[0075] Optional, reference Figure 1 The edge of the anchoring region 21 adjacent to the outer electrode 31 is polygonal or circular; the inter-ring electrode 32 is arc-shaped, and the inner electrode 33 is fan-shaped.

[0076] Specifically, the edge of the anchoring region 21 adjacent to the outer electrode 31 may be an octagon (when n=2 mode) or a dodecagon (when n=3 mode), or may be a circle. When the gyroscope operates in n=2 mode, when the number of inner electrodes 33 is 8, the sector angle of the inner electrode 33 is equal to 45°, and when the number of inner electrodes 33 is 16, the sector angle of the inner electrode 33 is equal to 22.5°. When the gyroscope operates in n=3 mode, when the number of inner electrodes 33 is 12, the sector angle of the inner electrode 33 is equal to 30°, and when the number of inner electrodes 33 is 24, the sector angle of the inner electrode 33 is equal to 15°.

[0077] The embodiment of the present invention further provides a method for preparing a MEMS gyroscope, which is used to form the MEMS gyroscope described in any embodiment of the present invention. Fig.11 is a flowchart of a method for preparing a MEMS gyroscope provided by an embodiment of the present invention, with reference to Fig.11 , the preparation method of the MEMS gyroscope includes the following steps.

[0078] S110, patterning the first surface of the device material layer to form a cavity.

[0079] Fig.12This is a schematic diagram of the device material layer after the cavity is formed. Fig.12 The device material layer 201 may be a silicon wafer, which is a highly doped silicon wafer having the characteristics of strong conductivity and low resistivity. The cavity 41 may be formed by etching the device material layer 201. Exemplarily, the device material layer 201 is a double-sided polished single crystal silicon wafer, and the cavity 41 is made by deep silicon etching.

[0080] S120, forming a barrier layer at the bottom of the cavity.

[0081] in, Fig.13 is a schematic diagram after the barrier layer is formed, refer to Fig.13 , a barrier layer 50 is formed by depositing a layer of barrier material at the bottom of the cavity 41. The barrier layer 50 is used as a reaction stop layer for subsequent deep silicon etching, that is, the etching material for etching the device material layer 201 cannot etch the barrier layer 50. The barrier layer 50 is used as a reaction stop layer for subsequent etching of the device material layer 201. The material used for the barrier layer 50 can be metal or other materials.

[0082] S130, bonding the first surface of the device material layer to the substrate.

[0083] Fig.14 This is a schematic diagram of the device material layer and the substrate after bonding, refer to Fig.14 , the device material layer 201 with the cavity 41 is reversed, the cavity 41 is located at the bottom, and the device material layer 201 is bonded to the substrate 10; the material of the substrate 10 can be glass or the like.

[0084] S140, patterning the second surface of the device material layer to form a device layer having an anchoring region, an electrode, a plurality of connecting beams and at least two vibration rings.

[0085] Specifically, Fig.15 This is a schematic diagram after the pad is formed. Fig.16 This is a schematic diagram after forming the device layer and removing the barrier layer. Fig.15 The device material layer 201 can be thinned to form the pad 60, and then the device material layer 201 is etched to form the device layer 20. The thickness of the device material layer 201 after thinning minus the depth of the cavity 41 is the height of the external electrode, the connecting beam and the vibration ring.

[0086] S150, removing the barrier layer.

[0087] Specifically, the barrier layer may be removed by an etching process.

[0088] The method for preparing the MEMS gyroscope provided in the embodiment of the present invention belongs to the same inventive concept as the MEMS gyroscope provided in any embodiment of the present invention, and has corresponding beneficial effects. For technical details not detailed in this embodiment, please refer to the MEMS gyroscope provided in any embodiment of the present invention.

[0089] Optionally, the second surface of the device material layer is patterned to form a device layer having an anchoring area, an electrode, a plurality of connecting beams and at least two vibration rings, including: thinning the device material layer; forming a pad on a surface of the thinned device material layer away from the substrate; and etching the thinned device material layer to form a device layer having an anchoring area, an electrode, a plurality of connecting beams and at least two vibration rings.

[0090] Specifically, refer to Fig.15 , the device material layer 201 can be thinned by chemical mechanical polishing (CMP), and then a pad layer is deposited and patterned to form independent pads 60 on the vibration ring and the electrode to play the role of electrical connection. Fig.16 , a gap 42 is formed by deep silicon etching and stopped at the barrier layer 50, and then the barrier layer 50 is removed to release the vibration ring and the electrode structure.

[0091] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0092] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A MEMS gyroscope, characterized in that: include: A substrate and a device layer disposed on one side of the substrate; The device layer comprises an anchoring region, an electrode, a plurality of connecting beams and at least two vibration rings; the anchoring region surrounds the electrode, the plurality of connecting beams and the at least two vibration rings; The electrodes include a plurality of inner electrodes, a plurality of inter-ring electrodes and a plurality of outer electrodes; The at least two vibration rings surround the plurality of inner electrodes, and the plurality of inner electrodes are uniformly arranged around the center of the gyroscope; the plurality of inter-ring electrodes are arranged between adjacent vibration rings, and the plurality of inter-ring electrodes are uniformly arranged along the circumference of the vibration ring; the plurality of outer electrodes are arranged between the vibration ring and the anchoring area, and the plurality of outer electrodes are arranged in sequence along the circumference of the vibration ring; the plurality of connecting beams are arranged between the anchoring area and the outer electrodes, and the plurality of connecting beams are arranged in sequence along the circumference of the vibration ring; The anchoring area, the inter-ring electrode and the inner electrode are fixedly arranged on the substrate, and a cavity is provided between the connecting beam, the vibration ring and the outer electrode and the substrate; there are gaps between the connecting beam and the anchoring area, between the connecting beam and the outer electrode, between the outer electrode and the vibration ring, between the vibration ring and the inter-ring electrode, between adjacent inter-ring electrodes, and between the vibration ring and the inner electrode; adjacent vibration rings are connected by a plurality of straight beams, which are arranged in sequence along the circumference of the vibration ring, and both ends of each straight beam are connected to two adjacent vibration rings; one end of each connecting beam is connected to the vibration ring, and the other end is connected to the anchoring area; one end of each outer electrode is connected to the anchoring area.

2. The MEMS gyroscope according to claim 1, characterized in that: A plurality of first inter-ring electrodes and a plurality of second inter-ring electrodes are arranged between each two adjacent vibration rings; the plurality of first inter-ring electrodes are arranged in sequence along the circumference of the vibration ring, and the plurality of second inter-ring electrodes are arranged in sequence along the circumference of the vibration ring; the second inter-ring electrodes are arranged on a side of the first inter-ring electrodes adjacent to the inner electrode.

3. The MEMS gyroscope according to claim 2, characterized in that: There is a gap between adjacent inner electrodes, and the straight beam is arranged opposite to the gap; At least one of the first inter-ring electrodes and at least one of the second inter-ring electrodes are arranged between every two straight beams; Along the radial direction of the vibration ring, each of the inner electrodes is correspondingly provided with at least one outer electrode and at least one connecting beam.

4. The MEMS gyroscope according to claim 3, characterized in that: The straight beams and the gaps between two adjacent vibration rings are arranged one by one, and a first inter-ring electrode and a second inter-ring electrode are arranged between every two straight beams; Two outer electrodes and two connecting beams are arranged corresponding to each inner electrode. The two outer electrodes are symmetrical with respect to the symmetry axis of the corresponding inner electrode, and the two connecting beams are corresponding with respect to the symmetry axis of the corresponding inner electrode.

5. The MEMS gyroscope according to claim 1, characterized in that: The device layer is centrally symmetrical, and the device layer is symmetrical relative to a gap between any two inner electrodes.

6. The MEMS gyroscope according to claim 1, characterized in that: The connecting beam comprises a main body, a first connecting portion and a second connecting portion; the first connecting portion and the second connecting portion extend along the radial direction of the vibration ring; One end of the first connecting portion is connected to the anchoring area, and the other end is connected to the first end of the main body; One end of the second connecting portion is connected to the second end of the main body, and the other end is connected to the vibration ring; The main body includes at least one folded strip structure, which extends along the circumference of the vibration ring. The folded strip structure includes a first section, a second section and a third section. The first section, the second section and the third section are connected in sequence, and the first section and the third section extend along the circumference of the vibration ring.

7. The MEMS gyroscope according to claim 6, characterized in that: The shape of the first segment is at least one of a straight line, a broken line, a wavy line and a square wave; and / or the shape of the third segment is at least one of a straight line, a broken line, a wavy line and a square wave.

8. The MEMS gyroscope according to claim 1, characterized in that: The edge of the anchoring region adjacent to the outer electrode is polygonal or circular; The inter-ring electrodes are arc-shaped, and the inner electrodes are fan-shaped.

9. A method for preparing a MEMS gyroscope, characterized in that: For forming the MEMS gyroscope according to any one of claims 1 to 8, the method comprising: patterning the first surface of the device material layer to form a cavity; forming a barrier layer at the bottom of the cavity; bonding the first surface of the device material layer to the substrate; Patterning the second surface of the device material layer to form a device layer having an anchoring region, an electrode, a plurality of connecting beams and at least two vibration rings; The barrier layer is removed.

10. The preparation method according to claim 9, characterized in that: The second surface of the device material layer is patterned to form a device layer having an anchoring region, an electrode, a plurality of connecting beams and at least two vibration rings, including: Performing a thinning process on the device material layer; Forming a pad on a surface of the thinned device material layer away from the substrate; The thinned device material layer is etched to form a device layer having an anchoring region, an electrode, a plurality of connecting beams and at least two vibration rings.

Images