A bandwidth adjustment device for a MEMS accelerometer
By adding an adjustment block between the structural layer and the wiring layer of the MEMS accelerometer to form a sliding film damper, the problems of damping adjustment affecting performance and increasing cost in the prior art are solved, and the bandwidth and stability of the accelerometer are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- MT MICROSYST
- Filing Date
- 2024-01-24
- Publication Date
- 2026-06-26
AI Technical Summary
Existing technologies for adjusting the damping of MEMS accelerometers have issues that affect performance and increase costs, especially when adding damping comb teeth, which leads to a reduction in effective mass and capacitance.
An adjustment block is added between the structural layer and the wiring layer of the MEMS accelerometer. The distribution and gap of the adjustment block form a sliding damping, thereby adjusting the damping and thus adjusting the bandwidth characteristics of the accelerometer without affecting its performance.
Without increasing the chip area, the bandwidth and stability of the accelerometer were improved and the cost was reduced by adjusting the damping through the adjustment block.
Smart Images
Figure CN117929781B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of MEMS accelerometers, and more specifically, relates to a bandwidth adjustment device for MEMS accelerometers. Background Technology
[0002] MEMS accelerometers are chips that measure the acceleration of moving objects. They have advantages such as small size, light weight, low power consumption, high reliability, and low cost. This technology is playing an increasingly important role in military fields such as weaponry and navigation and control, as well as in civilian fields such as industry and the Internet.
[0003] MEMS accelerometers work by detecting external acceleration through the movement of the effective mass within the chip. A MEMS accelerometer can be considered a simple damped second-order system, where damping and frequency are key factors affecting the dynamic characteristics of the system. Once the accelerometer frequency is fixed, its bandwidth can be adjusted by regulating the damping.
[0004] Currently, in some countries with advanced MEMS technology, the only way to adjust structural damping during MEMS structure design is by adding damping combs to the accelerometer structure layer. This method reduces the effective mass and capacitance of the MEMS sensing structure, thus affecting accelerometer performance. To avoid impacting performance, the chip area must be increased, thereby increasing cost. This method has drawbacks in both performance and cost aspects. Summary of the Invention
[0005] The purpose of this invention is to provide a bandwidth adjustment device for MEMS accelerometers to solve the technical problem of the drawbacks of existing damping adjustment methods.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a bandwidth adjustment device for a MEMS accelerometer is provided. The MEMS accelerometer includes a cover layer, a structural layer, a wiring layer and a substrate layer connected in sequence, with a gap between the structural layer and the wiring layer. The bandwidth adjustment device includes a plurality of adjustment blocks located between the structural layer and the wiring layer. The adjustment blocks are all fixed at the unwired positions on the wiring layer, and the plurality of adjustment blocks are evenly distributed on the wiring layer.
[0007] In one possible implementation, based on the above technical solutions, the end face heights of all adjustment blocks are consistent.
[0008] In one possible implementation, based on the above technical solutions, the gap between the structural layer and the wiring layer is 1.5-1.7 μm.
[0009] In one possible implementation, based on the above technical solutions, the height of the adjustment block is 0.1-0.2 μm.
[0010] In one possible implementation, based on the above technical solutions, the height of the adjustment block is 0.15 μm.
[0011] In one possible implementation, based on the above technical solutions, a C-shaped groove and a wiring slot located in the middle of the C-shaped groove are formed on the wiring layer. The two side openings of the C-shaped groove and the side opening of the wiring slot are located on the same side of the wiring layer. An upper electrode wiring and a lower electrode wiring are provided in the C-shaped groove. One end of the upper electrode wiring is located in the C-shaped groove, and the other end extends out from the side opening of the C-shaped groove. One end of the lower electrode wiring is located in the C-shaped groove, and the other end extends out from the other side opening of the C-shaped groove. Quality wiring is provided in the wiring slot. The area on the wiring layer located in the C-shaped groove is the internal area, and the area located outside the C-shaped groove is the external area. Adjustment blocks are all set on the internal area and the external area and are symmetrically distributed in the wiring slot.
[0012] In one possible implementation, based on the above technical solutions, the adjustment block is a columnar body.
[0013] In one possible implementation, based on the above technical solutions, the planar shape of the end face of the adjustment block is a symmetrical shape.
[0014] In one possible implementation, based on the above technical solutions, the planar shape of the end face of the adjustment block is a polygon, a circle, or a near-circular shape.
[0015] The beneficial effects of the bandwidth adjustment device for MEMS accelerometers provided by this invention are as follows: Compared with the prior art, this invention adds an adjustment block between the structural layer and the wiring layer. When the movable structure of the structural layer and the wiring layer undergo parallel displacement, the gas will undergo shear deformation, thereby forming a sliding film damping. By changing the gap between the structural layer and the wiring layer or changing the distribution density of the adjustment block, the magnitude of the damping can be adjusted, thereby realizing the adjustment of the accelerometer bandwidth characteristics. Without affecting the performance of the accelerometer, chip area is saved, thereby reducing costs. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, 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.
[0017] Figure 1 This is a schematic diagram of a bandwidth adjustment device for a MEMS accelerometer provided in an embodiment of the present invention;
[0018] Figure 2 This is a plan view showing the structural layers in an embodiment of the present invention;
[0019] Figure 3 This is a plan view showing the wiring layer in an embodiment of the present invention;
[0020] Figure 4 This is a bandwidth curve of the accelerometer without a bandwidth adjustment device in this embodiment;
[0021] Figure 5 This is a bandwidth curve of the accelerometer with a bandwidth adjustment device in this embodiment;
[0022] Figure 6 This is a planar view for displaying the shape of the adjustment block in an embodiment of the present invention. Figure 1 ;
[0023] Figure 7 This is a planar view for displaying the shape of the adjustment block in an embodiment of the present invention. Figure 2 ;
[0024] Figure 8 This is a planar view for displaying the shape of the adjustment block in an embodiment of the present invention. Figure 3 .
[0025] The labels for the attached figures are as follows:
[0026] 1. Cover plate layer; 2. Structural layer; 21. Effective mass; 22. Structural beam; 23. Connection structure; 24. Anchor point structure; 3. Wiring layer; 31. C-groove; 32. Wiring groove; 33. Upper electrode wiring; 34. Lower electrode wiring; 35. Mass wiring; 36. Internal area; 37. External area; 4. Substrate layer; 5. Adjustment block. Detailed Implementation
[0027] To make the technical problems, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are only a part of the embodiments of this application, not all of them. The specific embodiments described herein are only used to explain the invention and are not intended to limit the invention. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0028] It should be further noted that the accompanying drawings and embodiments of the present invention mainly describe the concept of the present invention. Based on this concept, some specific forms and arrangements of connection relationships, positional relationships, power mechanisms, power supply systems, hydraulic systems and control systems may not be fully described. However, under the premise that those skilled in the art understand the concept of the present invention, they can implement the above-mentioned specific forms and arrangements in a well-known manner.
[0029] When a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.
[0030] The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself. The terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.
[0031] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways, and the spatial relative descriptions used herein will be interpreted accordingly.
[0032] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, and "several" means one or more, unless otherwise explicitly specified.
[0033] The present invention will now describe a bandwidth adjustment device for a MEMS accelerometer.
[0034] like Figure 1 and Figure 3 As shown, one embodiment of the present invention provides a bandwidth adjustment device for a MEMS accelerometer. The MEMS accelerometer includes a cover layer 1, a structural layer 2, a wiring layer 3, and a substrate layer 4 connected in sequence. There is a gap between the structural layer 2 and the wiring layer 3. The bandwidth adjustment device includes a plurality of adjustment blocks 5 located between the structural layer 2 and the wiring layer 3. The adjustment blocks 5 are all fixed at the unwired positions on the wiring layer 3, and the plurality of adjustment blocks 5 are evenly distributed on the wiring layer 3.
[0035] This embodiment provides a bandwidth adjustment device for MEMS accelerometers. Compared with the prior art, by adding an adjustment block 5 between the structural layer 2 and the wiring layer 3, when the movable structure of the structural layer 2 and the wiring layer 3 undergo parallel displacement, the gas will generate shear deformation, thereby forming a sliding film damping. By changing the gap between the structural layer 2 and the wiring layer 3 or changing the distribution density of the adjustment block 5, the magnitude of the damping can be adjusted, thereby realizing the adjustment of the accelerometer bandwidth characteristics. Without affecting the accelerometer performance, chip area is saved, thereby reducing costs.
[0036] like Figure 1 As shown, based on the above embodiments, the present invention provides another specific embodiment as follows:
[0037] All adjustment blocks 5 have the same end face height. This ensures more uniform damping between structural layer 2 and wiring layer 3, improving the operational stability of the MEMS accelerometer.
[0038] like Figure 1 As shown, based on the above embodiments, the present invention provides another specific embodiment as follows:
[0039] The gap between structural layer 2 and wiring layer 3 is 1.5-1.7 μm. The height of adjustment block 5 is 0.1-0.2 μm.
[0040] Specifically, in this embodiment, the gap between the wiring positions of the structural layer 2 and the wiring layer 3 is 1.6 μm, and the gap between the unwiring positions of the structural layer 2 and the wiring layer 3 is 1.75 μm; the height of the adjustment block 5 and the wiring layer 3 are the same, both being 0.15 μm.
[0041] like Figures 1 to 2 As shown, based on the above embodiments, the present invention provides another specific embodiment as follows:
[0042] Structural layer 2 includes effective mass 21, structural beam 22, connecting structure 23 and anchor point structure 24. The connecting structure 23 is used to connect structural beam 22 and anchor point structure 24.
[0043] like Figures 1 to 3 As shown, based on the above embodiments, the present invention provides another specific embodiment as follows:
[0044] The wiring layer 3 has a C-shaped groove 31 and a wiring groove 32 located in the middle of the C-shaped groove 31. The two side openings of the C-shaped groove 31 and the side opening of the wiring groove 32 are located on the same side of the wiring layer 3. The C-shaped groove 31 has an upper electrode plate wiring 33 and a lower electrode plate wiring 34. One end of the upper electrode plate wiring 33 is located in the C-shaped groove 31, and the other end extends out from the side opening of the C-shaped groove 31. One end of the lower electrode plate wiring 34 is located in the C-shaped groove 31, and the other end extends out from the other side opening of the C-shaped groove 31. The wiring groove 32 has a mass wiring 35. The area in the wiring layer 3 located in the C-shaped groove 31 is the inner area 36, and the area outside the C-shaped groove 31 is the outer area 37. The adjustment blocks 5 are all set on the inner area 36 and the outer area 37, and are symmetrically distributed in the wiring groove 32.
[0045] Specifically, the upper electrode wiring 33 is used to connect the upper electrode of the structural layer 2, the lower electrode wiring 34 is used to connect the lower electrode of the structural layer 2, and the mass wiring 35 is used to connect the effective mass 21 of the structural layer 2. The inner region 36 and the outer region 37 are the unwired areas of the wiring layer 3.
[0046] The adjustment blocks 5 in the inner region 36 and the adjustment blocks 5 in the outer region 37 are symmetrically arranged in the wiring groove 32, which can make the sliding film damping generated between the structural layer 2 and the wiring layer 3 more uniform, make the shear deformation of the airflow more stable, and thus improve the working stability of the MEMS accelerometer.
[0047] like Figures 4 to 5 As shown, when there is no structure in the outer region 37 and the inner region 36, the sliding damping between the MEMS accelerometer and the wiring layer 3 is very small, resulting in a rapid rise in the dynamic characteristic curve of the accelerometer and a large amplification factor of the structure. When the outer region 37 and the inner region 36 are equipped with the adjustment block 5, it can be calculated that the sliding damping of the accelerometer is greatly increased, thereby effectively reducing the amplification factor of the structure and lowering the Q value of the structure, thus suppressing the dynamic characteristic curve of the accelerometer. From the perspective of accelerometer performance, this means improving the bandwidth characteristic curve. The bandwidth of the accelerometer is adjusted by utilizing the structure of the wiring layer 3, thereby improving the in-band flatness.
[0048] Specifically, the magnitude of the sliding damping is related to the gas gap between the structural layer 2 and the wiring layer 3, and the density of the adjustment blocks 5. The smaller the gas gap between the structural layer 2 and the wiring layer 3, the greater the damping; the denser the adjustment blocks 5 are, the greater the damping.
[0049] from Figure 4 and Figure 5 The comparison shows that after adding the bandwidth adjustment device, the damping of the accelerometer increased from 0.36 to 0.58, the Q value of the structure was greatly reduced, and the bandwidth of the accelerometer was optimized from 360Hz (+3dB) to 586Hz (-3dB), which greatly improved the bandwidth of the accelerometer and optimized the in-band flatness, with remarkable results.
[0050] like Figures 6 to 8 As shown, based on the above embodiments, the present invention provides another specific embodiment as follows:
[0051] Adjusting block 5 is a columnar body. The planar shape of the end face of adjusting block 5 is a symmetrical figure.
[0052] Specifically, in this embodiment, the planar shape of the end face of the adjustment block 5 is a polygon, a circle, or a near-circular shape.
[0053] Specifically, in this embodiment, the planar shape of the end face of the adjustment block 5 is rectangular.
[0054] Alternatively, in another embodiment, the planar shape of the end face of the adjusting block 5 is circular.
[0055] The conventional symmetrical pattern setting facilitates both the production and manufacturing of adjustment block 5 and the installation of the array of adjustment block 5 onto wiring layer 3.
[0056] Alternatively, in another embodiment, the planar shape of the end face of the adjustment block 5 may also be an irregular shape.
[0057] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
[0058] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0059] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.
Claims
1. A bandwidth adjustment device for a MEMS accelerometer, characterized in that, The MEMS accelerometer includes a cover plate layer (1), a structural layer (2), a wiring layer (3), and a substrate layer (4) connected in sequence. There is a gap between the structural layer (2) and the wiring layer (3). The bandwidth adjustment device includes a plurality of adjustment blocks (5) located between the structural layer (2) and the wiring layer (3). The adjustment blocks (5) are all fixed at the unwired positions on the wiring layer (3), and the plurality of adjustment blocks (5) are evenly distributed on the wiring layer (3). When the movable structure of the structural layer (2) and the wiring layer (3) undergo parallel displacement, the gas in the gap undergoes shear deformation, and a sliding film damping is formed on the surface of the adjusting block (5); the magnitude of the sliding film damping is adjusted by changing the gap between the structural layer (2) and the wiring layer (3) or by changing the distribution density of the adjusting block (5).
2. The bandwidth adjustment device for a MEMS accelerometer as described in claim 1, characterized in that, All the adjusting blocks (5) have the same end face height.
3. The bandwidth adjustment device for a MEMS accelerometer as described in claim 1, characterized in that, The gap between the structural layer (2) and the wiring layer (3) is 1.5-1.8 μm.
4. A bandwidth adjustment device for a MEMS accelerometer as described in any one of claims 1-3, characterized in that, The height of the adjustment block (5) is 0.1-0.2 μm.
5. The bandwidth adjustment device for a MEMS accelerometer as described in claim 4, characterized in that, The height of the adjustment block (5) is 0.15 μm.
6. The bandwidth adjustment device for a MEMS accelerometer as described in claim 1, characterized in that, The wiring layer (3) has a C-shaped groove (31) and a wiring groove (32) located in the middle of the C-shaped groove (31). The two side openings of the C-shaped groove (31) and the side opening of the wiring groove (32) are located on the same side of the wiring layer (3). The C-shaped groove (31) has an upper electrode wiring (33) and a lower electrode wiring (34). One end of the upper electrode wiring (33) is located in the C-shaped groove (31), and the other end extends from the side opening of the C-shaped groove (31). The lower electrode wiring (34) has a C-shaped groove (31) and a wiring groove (32) located in the middle of the C-shaped groove (31). 34) One end is located in the C-shaped groove (31), and the other end extends from the other side of the C-shaped groove (31); the wiring groove (32) is provided with quality wiring (35); the area on the wiring layer (3) located in the C-shaped groove (31) is the inner area (36), and the area located outside the C-shaped groove (31) is the outer area (37). The adjustment blocks (5) are all set on the inner area (36) and the outer area (37), and are symmetrically distributed in the wiring groove (32).
7. The bandwidth adjustment device for a MEMS accelerometer as described in claim 1, characterized in that, The adjusting block (5) is a columnar body.
8. The bandwidth adjustment device for a MEMS accelerometer as described in claim 1, characterized in that, The planar shape of the end face of the adjustment block (5) is a symmetrical figure.
9. A bandwidth adjustment device for a MEMS accelerometer as described in claim 8, characterized in that, The planar shape of the end face of the adjustment block (5) is polygonal, circular or near-circular.