A single-chip six-axis sensor and its accelerometer

Abstract

The application provides a single-chip six-axis sensor and an accelerometer thereof, and the accelerometer comprises a Z-axis accelerometer. The Z-axis accelerometer comprises a Z-axis mass block, a first space and a second space are defined in the Z-axis mass block, an anchor point structure is located in the first space, a rotating shaft is located in the first space and is arranged parallel to the X / Y axis, the rotating shaft is connected with the anchor point structure and the Z-axis mass block, the mass on one side of the rotating shaft is different from the mass on the other side of the rotating shaft, so that the Z-axis mass block performs seesaw movement with the rotating shaft as the axis, and an air damping unit is located in the second space, the air damping unit comprises a first anchor point, a plurality of fixed damping comb teeth connected with the first anchor point, a plurality of movable damping comb teeth connected with the Z-axis mass block, and the fixed damping comb teeth and the movable damping comb teeth are arranged in an interdigital mode. Compared with the prior art, the reliability of the accelerometer in the low-pressure cavity is enhanced, the production cost is reduced, and the integration degree is improved by designing the air damping structure and the limiters with different stiffnesses.

Description

[Technical Field]

[0001] This invention relates to the field of micromechanical systems technology, and in particular to a single-chip six-axis sensor and its accelerometer. [Background Technology]

[0002] MEMS (Micro-Electro-Mechanical System) capacitive accelerometers are widely used in consumer electronics, the Internet of Things (IoT), and industrial measurement due to their small size, low cost, and excellent performance. Intensifying competition in the consumer electronics market has placed new demands on cost and integration. To achieve this, current six-axis products (3-axis accelerometer + 3-axis gyroscope) are shifting from having the accelerometer and gyroscope on separate chips to fabricating both on a single chip. This process encounters a challenge: air pressure. Accelerometers require higher air pressure to increase air damping, typically around 400 mBar, improving reliability in shock environments. Gyroscopes, on the other hand, require lower air pressure, typically <5 mBar, the lower the better. Since these two chambers are fabricated simultaneously, their internal pressures increase and decrease simultaneously, increasing the pressure difference between the two chambers. Controlling this chamber pressure is a current manufacturing challenge. This is currently addressed by employing special packaging processes and using getters, but this significantly increases production costs.

[0003] Therefore, there is an urgent need to propose a new technical solution to address the above problems. [Summary of the Invention]

[0004] One of the objectives of this invention is to provide a single-chip six-axis sensor and its accelerometer, which can solve the problems of low air damping and poor shock resistance of accelerometers under low pressure conditions.

[0005] According to one aspect of the present invention, an accelerometer is provided, comprising a Z-axis accelerometer capable of sensing Z-axis acceleration. The Z-axis accelerometer includes: a Z-axis mass block defining a first space and a second space; an anchor structure located within the first space; and a rotating shaft located within the first space and placed parallel to the X-axis. The rotating shaft connects the anchor structure and the Z-axis mass block, wherein the mass of the Z-axis mass block on one side of the rotating shaft is different from the mass of the Z-axis mass block on the other side of the rotating shaft. The Z-axis mass block can perform a seesaw motion around the rotation axis; an air damping unit, located in the second space, includes a first anchor point, a plurality of fixed damping comb teeth connected to the first anchor point, and a plurality of movable damping comb teeth connected to the Z-axis mass block. The plurality of fixed damping comb teeth and the plurality of movable damping comb teeth are arranged in an interdigitated manner to form a plurality of air damping pairs; wherein, the X-axis and Y-axis are perpendicular to each other and define the plane on which the base of the Z-accelerometer is located, and the Z-axis is perpendicular to the plane defined by the X-axis and Y-axis.

[0006] According to another aspect of the present invention, the present invention provides a single-chip six-axis sensor, comprising: a gyroscope; an accelerometer, wherein the packaging pressure is 40 mBar to 200 mBar. The accelerometer includes a Z-axis accelerometer capable of sensing Z-axis acceleration. The Z-axis accelerometer comprises: a Z-axis mass block defining a first space and a second space; an anchor structure located within the first space; a rotating shaft located within the first space and placed parallel to the X / Y axes, the rotating shaft connecting the anchor structure and the Z-axis mass block, the mass of the Z-axis mass block on one side of the rotating shaft being different from the mass of the Z-axis mass block on the other side of the rotating shaft, the Z-axis mass block capable of a seesaw motion around the rotating shaft; and an air damping unit located within the second space, the air damping unit including a first anchor point, several fixed damping combs connected to the first anchor point, and several movable damping combs connected to the Z-axis mass block, the fixed and movable damping combs being arranged in an interdigitated pattern to form several air damping pairs; wherein the X and Y axes are perpendicular to each other and define the plane containing the base of the Z-accelerometer, and the Z-axis is perpendicular to the plane defined by the X and Y axes.

[0007] Compared with existing technologies, this invention enhances the reliability of the accelerometer in a low-pressure cavity by designing an air damping structure and limiters with different stiffnesses, thereby reducing production costs and improving integration. [Attached Image Description]

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments 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. Wherein:

[0009] Figure 1 This is a cross-sectional schematic diagram of most MEMS six-axis sensors currently on the market;

[0010] Figure 2 This is a cross-sectional schematic diagram of a novel MEMS six-axis sensor;

[0011] Figure 3 This is a schematic diagram of the overall structure of the Z-axis accelerometer in one embodiment of the present invention;

[0012] Figure 4 For example, in one embodiment of the present invention Figure 3 The diagram shows a cross-sectional view of the Z-axis accelerometer.

[0013] Figure 5 For example, in one embodiment of the present invention Figure 3 An enlarged schematic diagram of the anchor point structure shown.

Detailed Implementation Methods

[0014] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0015] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments. Unless otherwise specified, the terms "connected," "linked," and "connected" used herein to indicate electrical connection refer to direct or indirect electrical connection.

[0016] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the 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 invention. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0017] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," and "coupling" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0018] Please refer to Figure 1 As shown, this is a cross-sectional schematic diagram of most MEMS six-axis sensors currently on the market. Figure 1 The MEMS six-axis sensor 1 shown, namely the three-axis accelerometer and the three-axis gyroscope, are processed separately and then assembled together. The six-axis sensor 1 includes a discrete accelerometer 2 and a discrete gyroscope 3, as well as a signal processing circuit 4. Finally, the three chips are assembled together by injection molding using a molding compound 5 to form the final product.

[0019] The discrete accelerometer 2 and gyroscope 3 chips are larger in area than the single-chip integrated MEMS six-axis chip. In addition, they require additional assembly steps, such as multiple die-casting and wire bonding. In the highly competitive consumer electronics environment, they are gradually losing their competitiveness.

[0020] Instead, it is like Figure 2 The novel MEMS six-axis sensor 6 shown employs a single-chip integrated MEMS six-axis chip 7. Chip 7 contains an accelerometer 10, a gyroscope 12, and corresponding air chambers, all fabricated simultaneously. To ensure the internal pressure of the accelerometer's chamber 9 is greater than that of the gyroscope's chamber 11, chamber 9 is often smaller than chamber 11. How to increase the internal pressure of chamber 9 without increasing the pressure of chamber 11 is a pressing issue currently facing the industry. Currently, to control chamber 11 at a relatively low level, the pressure of chamber 9 must be sacrificed; typically, the pressure inside chamber 9 is only 40–200 mBar, far lower than the packaging pressure of accelerometers currently on the market, which is typically 400 mBar.

[0021] For accelerometer 2, because the mass of the Z-axis is larger than that of the X and Y axes, usually three times that of the X and Y axes, and the in-plane rotational stiffness of the Z-axis is small, it is often prone to colliding with the surrounding fixed structure under the action of external impact, generating debris, which can cause the structure to jam or cause significant changes in sensitivity and zero point.

[0022] To address the aforementioned problems in the existing technology, this invention provides a single-chip six-axis sensor and its accelerometer. Please refer to... Figure 3As shown, it is a schematic diagram of the overall structure of the Z-axis accelerometer in one embodiment of the present invention. Figure 3 The Z-axis accelerometer shown can sense Z-axis acceleration. The Z-axis accelerometer includes a Z-axis mass block (or movable mass block) 35, a fixed outer frame 33, a rotating shaft 13, an air damping unit 23, an anchor point structure 18, a first collision limiting structure 22, a second collision limiting structure 27, a third collision limiting structure 31, and a rigid limiter 34.

[0023] To better illustrate the structure of the Z-axis accelerometer shown in this invention, a three-dimensional Cartesian coordinate system can be established. Figure 3 In the illustrated embodiment, the X-axis and Y-axis are perpendicular to each other and define the plane on which the base of the Z-axis accelerometer lies. The Z-axis is perpendicular to the plane defined by the X-axis and Y-axis. A three-dimensional Cartesian coordinate system is established using the X-axis, Y-axis, and Z-axis. Figure 3 This is reflected in the diagram, where the X-axis runs along the left-right direction, the Y-axis runs along the up-down direction, and the Z-axis runs perpendicular to the paper.

[0024] like Figure 3 As shown, the Z-axis mass block (or movable mass block) 35 defines a first space 36, a second space 37, and a third space 38. Anchor structure 18 is located within the first space 36; a rotating shaft 13 is located within the first space 36 and placed parallel to the X-axis (or the extension direction of rotating shaft 13 is parallel to the Y-axis; this paper uses the example of rotating shaft 13 extending parallel to the X-axis). Rotating shaft 13 connects anchor structure 18 and Z-axis mass block 35. The mass of Z-axis mass block 35 located on one side (or above) of rotating shaft 13 (which can be called the mass of the first region 14 of Z-axis mass block 35) is different from the mass of Z-axis mass block 35 located on the other side (or below) of rotating shaft 13 (which can be called the mass of the second region 15 of Z-axis mass block 35), so that Z-axis mass block 35 can perform a seesaw-like movement around rotating shaft 13.

[0025] Please refer to Figure 4 As shown, this is one embodiment of the present invention. Figure 3 The diagram shows a cross-sectional view of the Z-axis accelerometer. Figure 4As shown, the Z-axis acceleration also includes a first Z-axis detection electrode (e.g., a negative sensing electrode) 16 and a second Z-axis detection electrode (e.g., a positive sensing electrode) 17. The first Z-axis detection electrode (or negative sensing electrode) 16 and the second Z-axis detection electrode (or positive sensing electrode) 17 are located below the Z-axis mass block 35 and are symmetrically arranged on the upper and lower sides of the rotating shaft 13. When the Z-axis acceleration input is sensed (or detected), the Z-axis mass block 35 will twist (or move like a seesaw) around the axis 13. The first Z-axis detection electrode 16 detects the change in distance from the Z-axis mass block 35 (or the first region 14 of the Z-axis mass block 35), and the second Z-axis detection electrode 17 detects the change in distance from the Z-axis mass block 35 (or the second region 15 of the Z-axis mass block 35). Specifically, after sensing the Z-axis acceleration, the capacitance of the first Z-axis detection electrode 16 and the second Z-axis detection electrode 17 increases and decreases, respectively. The difference between the two is used to obtain the capacitance change caused by the Z-axis acceleration, and thus the magnitude of the input Z-axis acceleration is obtained. For example, the capacitance change is converted into the magnitude of the acceleration in the Z-axis direction by the signal processing circuit 4.

[0026] exist Figure 3 In the illustrated embodiment, the air damping unit 23 is located within the second space 37 and distributed near the rotating shaft 13. The air damping unit 23 includes a first anchor point 24, a plurality of fixed damping comb teeth 25 connected to the first anchor point 24 and parallel to the X-axis, and a plurality of movable damping comb teeth 26 connected to the Z-axis mass block 35 and parallel to the X-axis. The plurality of fixed damping comb teeth 25 and the plurality of movable damping comb teeth 26 are arranged in an interdigitated manner to form a plurality of air damping pairs. When an impact occurs, the fixed damping comb teeth 25 and the movable damping comb teeth 26 compress the limited air between them, thereby effectively reducing the speed of the accelerometer during the impact process.

[0027] exist Figure 3 In the specific embodiment shown, there are four air damping units 23. Two air damping units 23 are located on the left side of the anchor structure 18 and on the upper and lower sides of the rotating shaft 13, respectively. The other two air damping units 23 are located on the right side of the anchor structure 18 and on the upper and lower sides of the rotating shaft 13, respectively. The four air damping units 23 are symmetrically distributed about the X-axis and Y-axis.

[0028] exist Figure 3 and Figure 4 In the embodiment shown, the first anchor point 24 is fixedly disposed on the substrate (not shown); the first Z-axis detection electrode 16 and the second Z-axis detection electrode 17 are fixedly disposed on the substrate (not shown); the Z-axis mass block 35 and the rotating shaft 13 are suspended above the substrate; the fixed damping comb teeth 25 and the movable damping comb teeth 26 are suspended above the substrate.

[0029] exist Figure 3In the illustrated embodiment, the anchor structure 18 includes a second anchor point 19, a buffer beam 20, and a serpentine beam 21. The buffer beam 20 connects the second anchor point 19 and the rotating shaft 13. The buffer beam 20 reduces the impact stress received by the rotating shaft 13 during impact. In one embodiment, the buffer beam 20 is designed to have a stiffness in the X / Y directions between 200 and 2000 N / m. The serpentine beam 21 is located on the side of the second anchor point 19 away from the rotating shaft 13, with one end connected to the second anchor point 19 and the other end close to the Z-axis mass block 35.

[0030] Please refer to Figure 5 As shown, this is one embodiment of the present invention. Figure 3 An enlarged schematic diagram of the anchor point structure 18 shown. Figure 3 and Figure 5 In the specific embodiment shown, the serpentine beam 21 has a circular first collision limiting structure 22 at the other end near the Z-axis mass block 35. The circular contact surface on the first collision limiting structure 22 exhibits a decreasing height distribution; that is, the height of the first collision limiting structure 22 decreases along the Y-axis direction near the Z-axis mass block 35. Considering the collision contact and deformation of the serpentine beam 21, the first collision limiting structure 22 can maintain contact stability and reduce the contact area to avoid microscale adhesion. In the design, the distance between the first collision limiting structure 22 and the surrounding movable structure is minimized. Depending on the manufacturing capability, the collision distance is typically set to 1.4–2.5 μm; that is, the collision distance between the first collision limiting structure 22 and the Z-axis mass block 35 is designed to be 1.4–2.5 μm. By designing the collision spacing, when a collision occurs, the first collision limiting structure 22 will first contact the Z-axis mass block 35, providing a reaction force to suppress the movement of the Z-axis mass block 35. The stiffness of the serpentine beam 21 is designed to be 500-2000 N / m, mainly used to absorb the impact in the 1500G range most likely to be encountered in a drop event.

[0031] exist Figure 3 In the specific embodiment shown, there are two anchor point structures 18, distributed on the upper and lower sides of the rotating shaft 13; the two anchor point structures 18 are symmetrically distributed about the X-axis; the second anchor point 19 is fixedly set on the base (not shown); the buffer beam 20 and the serpentine beam 21 are suspended above the base.

[0032] The second collision limiting structure 27 is located within the third space 38, and it can simultaneously suppress impacts in the X / Y directions. Figure 3In the illustrated embodiment, the second collision limiting structure 27 includes a third anchor point 28 and a plurality of cantilever beam structures 29 located outside the third anchor point 28. One end of each cantilever beam structure 29 is fixed to the third anchor point 28, and the other end is close to the Z-axis mass block 35. In one embodiment, the collision distance between the collision contact point 30 at the other end of the cantilever beam 29 and the Z-axis mass block 35 (i.e., the collision distance between the cantilever beam 29 or the second collision limiting structure 27 and the Z-axis mass block 35) is 0.2 to 0.5 μm larger than the collision distance between the first collision limiting structure 22 and the Z-axis mass block 35 (i.e., the collision distance between the serpentine beam 21 and the Z-axis mass block 35). In other words, the collision distance between the second collision limiting structure 27 and the Z-axis mass block 35 is larger than the collision distance between the first collision limiting structure 22 and the Z-axis mass block 35. In design, the stiffness of the cantilever beam structure 29 is 2000–4000 N / m, mainly used to absorb impact events with a peak impact value <10000G.

[0033] exist Figure 3 In the specific embodiment shown, the cantilever beam structure 29 is a Z-shaped right-angle structure; there are four cantilever beam structures 29, which are located on the four sides of the third anchor point 28 respectively; the third anchor point 28 is fixedly set on the base (not shown); the cantilever beam structure 29 is suspended above the base; there are two second collision limiting structures 27, and both second collision limiting structures 27 are set on the same side of the rotating shaft 13 (for example, below the rotating shaft 13).

[0034] exist Figure 3 In the illustrated embodiment, the Z-axis mass block 35 is surrounded by a fixed outer frame 33. A third collision limiting structure 31 is distributed around the outer perimeter of the Z-axis mass block 35 and between the fixed outer frame 33. The collision distance between the collision contact point 32 of the third collision limiting structure 31 and the fixed outer frame 33 (i.e., the collision distance between the third collision limiting structure 31 and the fixed outer frame 33) is 0.5–0.8 μm larger than the collision distance between the first collision limiting structure 22 and the Z-axis mass block 35 (or the collision distance between the serpentine beam 21 and the Z-axis mass block 35). In other words, the collision distance between the third collision limiting structure 31 and the fixed outer frame 33 is larger than the collision distance between the cantilever beam 29 or the second collision limiting structure 27 and the Z-axis mass block 35. In design, the stiffness of the third collision limiting structure 31 is designed to be 10,000–20,000 N / m, primarily for absorbing impact events with a peak impact value <= 20,000 G.

[0035] To prevent beam structures from fracturing due to excessive deformation stress under the worst impact conditions, such as ultimate impacts of up to 1000 kg and 1 µs, in Figure 3 In the embodiment shown, a rigid limiter 34 is placed between the outer side of the Z-axis mass block 35 and the fixed outer frame 33.

[0036] exist Figure 3In the specific embodiment shown, the third collision limiting structure 31 has 8 collision contact points 32, which are distributed on the four sides of the Z-axis mass block 35 (up, down, left, and right); and there are 2 rigid limiters 34, which are distributed on the upper and lower sides of the Z-axis mass block 35.

[0037] According to another aspect of the present invention, the present invention provides a single-chip six-axis sensor, comprising: a gyroscope; and an accelerometer as provided in the present invention, wherein the accelerometer is packaged under a pressure of 40 mBar to 200 mBar.

[0038] In summary, this invention improves the reliability of the Z-axis accelerometer in low-pressure environments through two approaches. First, the air damping unit 23 increases air damping, reducing the velocity and frequency of collisions, thus decreasing the likelihood of debris generation and improving device reliability. Second, collision structures with different stiffnesses (e.g., the first collision limiting structure 22, the second collision limiting structure 27, the third collision limiting structure 31, and the hard limiter 34) sequentially collide with the Z-axis mass block 35 to reduce the stress on the structure during collisions. Thus, the Z-axis accelerometer provided by this invention can operate normally under relatively low packaging pressures of 40 mBar to 200 mBar. By improving the reliability of the accelerometer in low vacuum conditions, the additional requirements for packaging pressure in the single-chip six-axis sensor are reduced, further lowering production costs.

[0039] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0040] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications and variations to the above embodiments within the scope of the present invention.

Claims

1. An accelerometer, characterized in that, It includes a Z-axis accelerometer, which is capable of sensing Z-axis acceleration, and the Z-axis accelerometer includes: The Z-axis mass block has a first space and a second space defined within it. An anchor point structure, which is located within the first space; A pivot is located within the first space and placed parallel to the X or Y axis. The pivot connects the anchor point structure and the Z-axis mass block. The mass of the Z-axis mass block on one side of the pivot is different from the mass of the Z-axis mass block on the other side of the pivot. The Z-axis mass block can perform a seesaw motion around the pivot. An air damping unit is located in the second space. The air damping unit includes a first anchor point, a plurality of fixed damping comb teeth connected to the first anchor point, and a plurality of movable damping comb teeth connected to the Z-axis mass block. The plurality of fixed damping comb teeth and the plurality of movable damping comb teeth are arranged in an interdigitated manner to form a plurality of air damping pairs. The X-axis and Y-axis are perpendicular to each other and define the plane on which the base of the Z-axis accelerometer is located. The Z-axis is perpendicular to the plane defined by the X-axis and Y-axis. The anchor point structure includes a second anchor point, a buffer beam, and a serpentine beam. The buffer beam connects the second anchor point and the rotating shaft; The serpentine beam is located on the side of the second anchor point away from the axis of rotation, with one end connected to the second anchor point and the other end close to the Z-axis mass block. The serpentine beam has a first collision limiting structure at the other end near the Z-axis mass block; A third space is also defined within the Z-axis mass block. The Z-axis accelerometer also includes a second collision limiting structure located in the third space, which can simultaneously suppress impacts in the X / Y directions. The second collision limiting structure includes a third anchor point and several cantilever beam structures located outside the third anchor point. One end of each cantilever beam structure is fixed to the third anchor point, and the other end is close to the Z-axis mass block. The cantilever beam structure is a Z-shaped right-angle structure.

2. The accelerometer according to claim 1, characterized in that, The Z-axis accelerometer also includes a first Z-axis detection electrode and a second Z-axis detection electrode. The first Z-axis detection electrode and the second Z-axis detection electrode are located below the Z-axis mass block and are disposed on both sides of the rotating shaft; When a Z-axis acceleration input is sensed, the Z-axis mass block will move in a seesaw motion around the rotation axis. The first Z-axis detection electrode detects the change in distance from the Z-axis mass block, and the second Z-axis detection electrode detects the change in distance from the Z-axis mass block.

3. The accelerometer according to claim 1, characterized in that, The air damping units are distributed near the rotating shaft, and the fixed damping comb teeth and the movable damping comb teeth are parallel to the rotating shaft. There are four air damping units, two of which are located on one side of the anchor point structure in the X-axis direction and on both sides of the rotating shaft in the Y-axis direction; the other two air damping units are located on the other side of the anchor point structure in the X-axis direction and on both sides of the rotating shaft in the Y-axis direction. The four air damping units are symmetrically distributed about the X and Y axes.

4. The accelerometer according to claim 1, characterized in that, The height of the first collision limiting structure decreases along the Y-axis direction close to the Z-axis mass block, and the top is rounded.

5. The accelerometer according to claim 1, characterized in that, The anchor point structure consists of two points, distributed on both sides of the Y-axis direction of the rotating shaft; The two anchor point structures are symmetrically distributed about the X-axis.

6. The accelerometer according to claim 1, characterized in that, There are four cantilever beam structures, located on the four sides of the third anchor point.

7. The accelerometer according to claim 1, characterized in that, The Z-axis accelerometer also includes: A fixed outer frame surrounds the Z-axis mass block. The third collision limiting structure is disposed around the outer perimeter of the Z-axis mass block and between the fixed outer frame.

8. The accelerometer according to claim 7, characterized in that, The Z-axis accelerometer also includes a rigid limiter. The rigid limiter is disposed between the outer side of the Z-axis mass block and the fixed outer frame.

9. The accelerometer according to claim 8, characterized in that, The collision distance between the second collision limiting structure and the Z-axis mass block is larger than the collision distance between the first collision limiting structure and the Z-axis mass block. The collision distance between the third collision limiting structure and the fixed outer frame is larger than the collision distance between the second collision limiting structure and the Z-axis mass block.

10. The accelerometer according to claim 7, characterized in that, The collision distance between the first collision limiting structure and the Z-axis mass block is designed to be 1.4~2.5um, and its stiffness is 500~2000N / m; The collision distance between the second collision limiting structure and the Z-axis mass block is 0.2~0.5um larger than the collision distance between the first collision limiting structure and the Z-axis mass block; Its stiffness is 2000~4000 N / m; The collision distance between the third collision limiting structure and the fixed outer frame is 0.5~0.8um larger than the collision distance between the first collision limiting structure and the Z-axis mass block, and its stiffness is 10000~20000N / m.

11. A single-chip six-axis sensor, characterized in that, It includes: Gyroscope; The accelerometer as described in any one of claims 1-10.

12. The single-chip six-axis sensor according to claim 11, characterized in that, The accelerometer is packaged under a pressure of 40 mBar to 200 mBar.

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