CN116298385A

CN116298385A - Single-chip six-axis sensor and accelerometer thereof

Info

Publication number: CN116298385A
Application number: CN202310092141.XA
Authority: CN
Inventors: 刘尧; 凌方舟; 蒋乐跃; 苏云鹏
Original assignee: Memsic Semiconductor Wuxi Co Ltd
Current assignee: Memsic Semiconductor Wuxi Co Ltd
Priority date: 2022-12-30
Filing date: 2023-02-09
Publication date: 2023-06-23
Also published as: CN219758288U

Abstract

The invention provides a single-chip six-axis sensor and an accelerometer thereof. The Z-axis accelerometer includes: a Z-axis mass defining a first space and a second space therein; an anchor point structure located within the first space; the rotating shaft is positioned in the first space and is parallel to the X/Y axis, the rotating shaft is connected with the anchor point structure and the Z-axis mass block, and the mass of the Z-axis mass block positioned on one side of the rotating shaft is different from that of the Z-axis mass block positioned on the other side of the rotating shaft, so that the Z-axis mass block can perform seesaw type motion by taking the rotating shaft as an axis; the air damping unit is located in the second space and comprises 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, wherein the fixed damping comb teeth and the movable damping comb teeth are distributed in an interdigital mode. Compared with the prior art, the air damping structure is designed, the limiters with different rigidities are used for enhancing the reliability of the accelerometer in the low-pressure cavity, reducing the production cost and improving the integration level.

Description

Single-chip six-axis sensor and accelerometer thereof

[ field of technology ]

The invention relates to the technical field of micro-mechanical systems, in particular to a single-chip six-axis sensor and an accelerometer thereof.

[ background Art ]

MEMS (Micro-Electro-Mechanical System, i.e. Micro-electromechanical system) capacitive accelerometers are widely used in consumer electronics, internet of things, and industrial measurement fields due to their small size, low cost, and excellent performance. Consumer electronics competition is increasingly stronger, new requirements are put on cost and integration level, in order to achieve the purpose, the current six-axis product (3-axis acceleration+3-axis gyroscope) is changed from an original accelerometer, the gyroscopes are respectively positioned on two independent chips to a mode of processing the gyroscopes and the accelerometers on the same chip, in the process, people encounter a problem that air pressure is that the air pressure is high, the accelerometer needs high air pressure to increase air damping, generally about 400mBar, the reliability of the device in an impact environment is improved, and the gyroscope needs low air pressure, generally <5mBar, and the smaller the better. Because these two cavities are simultaneously formed by processing, the internal pressure is increased and reduced simultaneously, the strong pressure difference of the two cavities is improved, and how to control the cavity pressure is a problem encountered in the current process, the problem is solved by adopting a special packaging process and matching with the use of a getter, so that the production cost can be greatly increased.

Therefore, a new solution is needed to solve the above problems.

[ invention ]

The invention aims to provide a single-chip six-axis sensor and an accelerometer thereof, which can solve the problems of small air damping and poor shock resistance of the accelerometer under a low pressure condition.

According to one aspect of the present invention there is provided an accelerometer comprising a Z-axis accelerometer capable of sensing Z-axis acceleration, the Z-axis accelerometer comprising: a Z-axis mass defining a first space and a second space therein; an anchor point structure located within the first space; the rotating shaft is positioned in the first space and is parallel to the X axis, the rotating shaft is connected with the anchor point structure and the Z-axis mass block, the mass of the Z-axis mass block positioned on one side of the rotating shaft is different from the mass of the Z-axis mass block positioned on the other side of the rotating shaft, and the Z-axis mass block can perform seesaw type movement by taking the rotating shaft as an axis; the air damping unit is positioned in the second space and comprises 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, wherein the fixed damping comb teeth and the movable damping comb teeth are distributed in an interdigital manner to form a plurality of air damping pairs; wherein the X-axis and the Y-axis are perpendicular to each other and define a plane in which the substrate of the Z-accelerometer lies, and the Z-axis is perpendicular to the plane defined by the X-axis and the Y-axis.

According to another aspect of the present invention, there is provided a single chip six axis sensor comprising: a gyroscope; and the packaging pressure of the accelerometer is 40mBar to 200mBar. The accelerometer includes a Z-axis accelerometer capable of sensing a Z-axis acceleration, the Z-axis accelerometer including: a Z-axis mass defining a first space and a second space therein; an anchor point structure located within the first space; the rotating shaft is positioned in the first space and is parallel to the X/Y axis, the rotating shaft is connected with the anchor point structure and the Z-axis mass block, the mass of the Z-axis mass block positioned on one side of the rotating shaft is different from the mass of the Z-axis mass block positioned on the other side of the rotating shaft, and the Z-axis mass block can perform seesaw type movement by taking the rotating shaft as an axis; the air damping unit is positioned in the second space and comprises 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, wherein the fixed damping comb teeth and the movable damping comb teeth are distributed in an interdigital manner to form a plurality of air damping pairs; wherein the X-axis and the Y-axis are perpendicular to each other and define a plane in which the substrate of the Z-accelerometer lies, and the Z-axis is perpendicular to the plane defined by the X-axis and the Y-axis.

Compared with the prior art, the air damping structure is designed, the limiters with different rigidities are used for enhancing the reliability of the accelerometer in the low-pressure cavity, reducing the production cost and improving the integration level.

[ description of the drawings ]

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:

FIG. 1 is a schematic cross-sectional view of most MEMS six-axis sensors currently on the market;

FIG. 2 is a schematic cross-sectional view of a novel MEMS six-axis sensor;

FIG. 3 is a schematic diagram of the overall structure of a Z-axis accelerometer in one embodiment of the invention;

FIG. 4 is a schematic cross-sectional view of the Z-axis accelerometer of FIG. 3 in one embodiment of the invention;

fig. 5 is an enlarged schematic view of the anchor structure of fig. 3 in one embodiment of the present invention.

[ detailed description ] of the invention

In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.

Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic may be included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Unless specifically stated otherwise, the terms connected, or connected herein denote an electrical connection, either directly or indirectly.

In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the present invention, unless specifically stated and limited otherwise, the terms "mounted," "connected," "secured," "coupled," and the like are to be construed broadly; for example, the two parts can be fixedly connected, detachably connected or integrated; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

Referring to fig. 1, which is a schematic cross-sectional view of most MEMS six-axis sensors currently on the market, the MEMS six-axis sensor 1 shown in fig. 1, that is, a three-axis accelerometer and a 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, and further includes a signal processing circuit 4, and finally, the three chips are assembled together by using a molding compound 5 through injection molding, so as to form a final product.

The discrete accelerometer 2 and gyroscope 3 have larger chips than the single-chip integrated MEMS six-axis chip in area, and require additional assembly steps such as multiple die attach and multiple wire bonding. In environments where consumer electronics are highly competitive, their competitiveness is gradually lost.

Instead, the novel MEMS six-axis sensor 6 shown in fig. 2 adopts a single-chip integrated MEMS six-axis chip 7, and an accelerometer 10, a gyroscope 12 and a corresponding air cavity which are processed simultaneously are arranged inside the chip 7, so that in order to make the internal pressure of a cavity 9 of the accelerometer be greater than that of a cavity 11 of the gyroscope, the cavity 9 is often smaller than the cavity 11, and how to raise the internal pressure of the cavity 9 without increasing the pressure of the cavity 11 is an urgent problem encountered in the current industry. In order to control the cavity 11 at a relatively low level, the pressure of the cavity 9 has to be sacrificed, and the pressure in the cavity 9 is usually only 40-200 mBar, which is far smaller than the packaging pressure of the accelerometer in the market currently, and is usually 400mBar.

For accelerometer 2, because the mass of the Z axis is 3 times greater than that of X, Y axis, usually X, Y axis, and the rotational stiffness in the Z axis plane is small, it is easy to collide with surrounding fixed structures under the action of external impact, and chips are generated, which results in the structure being blocked, or sensitivity and zero point being greatly changed.

Aiming at the problems in the prior art, the invention provides a single-chip six-axis sensor and an accelerometer thereof. Referring to FIG. 3, a schematic diagram of the overall structure of a Z-axis accelerometer according to an embodiment of the invention is shown. The Z-axis accelerometer shown in fig. 3, which is capable of sensing Z-axis acceleration, includes a Z-axis mass (or movable mass) 35, a stationary housing 33, a rotating shaft 13, an air damping unit 23, an anchor point structure 18, a first bump stop structure 22, a second bump stop structure 27, a third bump stop structure 31, and a hard stop 34.

To better illustrate the structure of the Z-axis accelerometer shown in the present invention, a three-dimensional rectangular coordinate system may be established, in the embodiment shown in fig. 3, the X-axis and the Y-axis are perpendicular to each other and define a plane on which the substrate of the Z-axis accelerometer is located, the Z-axis is perpendicular to the plane defined by the X-axis and the Y-axis, and the three-dimensional rectangular coordinate system established by the X-axis, the Y-axis and the Z-axis is shown in fig. 3, where the X-axis is in the left-right direction, the Y-axis is in the up-down direction, and the Z-axis is in the direction perpendicular to the paper surface.

As shown in fig. 3, a first space 36, a second space 37, and a third space 38 are defined in the Z-axis mass (or movable mass) 35. Wherein the anchor point structure 18 is located within the first space 36; the rotation axis 13 is located in the first space 36 and is placed parallel to the X-axis (or the extension direction of the rotation axis 13 is parallel to the Y-axis, which is described herein as an example in which the extension direction of the rotation axis 13 is parallel to the X-axis), and the rotation axis 13 connects the anchor point structure 18 and the Z-axis mass 35. The mass of the Z-axis mass 35 on one side (or above) of the rotation axis 13 (which may be referred to as the mass of the first region 14 of the Z-axis mass 35) is different from the mass of the Z-axis mass 35 on the other side (or below) of the rotation axis 13 (which may be referred to as the mass of the second region 15 of the Z-axis mass 35) so that the Z-axis mass 35 makes a see-saw motion about the rotation axis 13.

Referring to FIG. 4, a schematic cross-sectional view of a Z-axis accelerometer as shown in FIG. 3 according to one embodiment of the invention is shown. As shown in fig. 4, the Z-axis acceleration further includes a first Z-axis detection electrode (e.g., sense negative electrode) 16 and a second Z-axis detection electrode (e.g., sense positive electrode) 17. The first Z-axis detection electrode (or sense negative electrode) 16 and the second Z-axis detection electrode (or sense positive electrode) 17 are positioned below the Z-axis mass 35 and symmetrically disposed on the upper and lower sides of the rotating shaft 13. When the sensing (or sensing) is performed to the input of the Z-axis acceleration, the Z-axis mass block 35 is twisted (or seesaw-type motion) with the rotation shaft 13 as the axis, the first Z-axis detection electrode 16 detects the change of the distance between the sensing electrode and the Z-axis mass block 35 (or the first area 14 of the Z-axis mass block 35), the second Z-axis detection electrode 17 detects the change of the distance between the sensing electrode and the Z-axis mass block 35 (or the second area 15 of the Z-axis mass block 35), specifically, the capacitance of the first Z-axis detection electrode 16 and the capacitance of the second Z-axis detection electrode 17 after sensing the Z-axis acceleration are increased and reduced, and the difference between the two changes the capacitance caused by the Z-axis acceleration, so as to obtain the magnitude of the input Z-axis acceleration, for example, the change of the capacitance is converted into the magnitude of the acceleration in the Z-axis direction by the signal processing circuit 4.

In the embodiment shown in fig. 3, the air damping unit 23 is located in the second space 37 and is distributed near the rotating shaft 13, the air damping unit 23 includes a first anchor point 24, a plurality of fixed damping combs 25 connected to the first anchor point 24 and parallel to the X-axis, a plurality of movable damping combs 26 connected to the Z-axis mass 35 and parallel to the X-axis, and the plurality of fixed damping combs 25 and the plurality of movable damping combs 26 are arranged in an interdigital arrangement to form a plurality of air damping pairs, and the fixed damping combs 25 and the movable damping combs 26 squeeze limited air therebetween when an impact occurs, thereby effectively reducing the speed of the accelerometer during the impact.

In the embodiment shown in fig. 3, there are four air damping units 23, where two air damping units 23 are located on the left side of the anchor point structure 18 and are located on the upper and lower sides of the rotating shaft 13 respectively; the other two air damping units 23 are positioned on the right side of the anchor point structure 18 and are respectively positioned on the upper side and the lower side of the rotating shaft 13; the four air damping units 23 are distributed symmetrically about the X-axis and the Y-axis as a whole.

In the embodiment shown in fig. 3 and 4, first anchor point 24 is fixedly disposed on a substrate (not shown); the first Z-axis detection electrode 16 and the second Z-axis detection electrode 17 are fixedly provided on a substrate (not shown); the Z-axis mass block 35 and the rotating shaft 13 are suspended above the substrate; fixed damping combs 25 and movable damping combs 26 are suspended above the base.

In the embodiment shown in fig. 3, the anchor structure 18 includes a second anchor 19, a bumper beam 20, and a serpentine beam 21. Wherein, the buffer beam 20 connects the second anchor point 19 and the rotating shaft 13, and the buffer beam 20 can reduce the impact stress received by the rotating shaft 13 during the impact process, and in one embodiment, the rigidity of the buffer beam 20 in the X/Y direction is designed to be between 200 and 2000N/m. The serpentine beam 21 is located on a side of the second anchor 19 remote from the axis of rotation 13, and one end of the serpentine beam 21 is connected to the second anchor 19 and the other end is adjacent to the Z-axis mass 35.

Please refer to fig. 5, which is an enlarged schematic diagram of the anchor point structure 18 shown in fig. 3 according to an embodiment of the present invention. In the embodiment shown in fig. 3 and 5, the serpentine beam 21 is provided with a circular first bump stop 22 at the other end near the Z-axis mass 35, and the circular contact surface on the first bump stop 22 is distributed in a decreasing manner in height, which means that the first bump stop 22 is distributed in a decreasing manner in height along the Y-axis near the Z-axis mass 35. The first bump stopper 22 can maintain the stability of the contact and can reduce the contact area in consideration of the deformation of the serpentine beam 21 in order to avoid the occurrence of the sticking phenomenon on the micro scale. In terms of design, the distance between the first collision limiting structure 22 and the surrounding movable structures is the smallest, and the collision distance is usually set to be 1.4-2.5 um according to the process capability, so to speak, 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 um. Through the design of collision interval, when collision happens, first collision limit structure 22 contacts Z axle mass 35 at first, provides reaction force, suppresses the motion of Z axle mass 35, selects 500 ~ 2000N/m on the rigidity design of snake-shaped beam 21, mainly used absorbs the impact in 1500G within range that the most easily meets in falling event.

In the embodiment shown in fig. 3, two anchor structures 18 are distributed on the upper and lower sides of the rotating shaft 13; the two anchor structures 18 are symmetrically distributed about the X-axis; the second anchor point 19 is fixedly arranged on a substrate (not shown); the bumper beam 20 and the serpentine beam 21 are suspended above the substrate.

The second bump stopper 27 is located in the third space 38, which can suppress the impact in the X/Y direction at the same time. In the embodiment shown in fig. 3, the second collision-limiting structure 27 includes a third anchor point 28, and a plurality of cantilever structures 29 located outside the third anchor point 28, one end of the cantilever structures 29 is fixed to the third anchor point 28, and the other end thereof 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 0.2-0.5 um greater 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), which is also referred to as the collision distance between the second collision limiting structure 27 and the Z-axis mass block 35 is greater than the collision distance between the first collision limiting structure 22 and the Z-axis mass block 35. The cantilever beam structure 29 has a stiffness of 2000-4000N/m in design, and is mainly used for absorbing impact events with an impact peak value < 10000G.

In the embodiment shown in fig. 3, the cantilever structure 29 is a Z-shaped right angle structure; the cantilever structures 29 are four and are respectively positioned at the four sides of the third anchor point 28; third anchor point 28 is fixedly disposed on a substrate (not shown); cantilever structure 29 is suspended above the substrate; the two second collision limiting structures 27 are arranged on the same side of the rotating shaft 13 (for example, below the rotating shaft 13).

In the embodiment shown in fig. 3, the Z-axis mass 35 is surrounded by a fixed outer frame 33; the third collision limiting structure 31 is distributed between the outer periphery of the Z-axis mass block 35 and the fixed outer frame 33, and 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 um greater than the collision distance between the first collision limiting structure 22 and the Z-axis mass block 35 (or the collision distance between the snake beam 21 and the Z-axis mass block 35), which is also said to be greater than the collision distance between the third collision limiting structure 31 and the fixed outer frame 33 and the cantilever beam 29 or the collision distance between the second collision limiting structure 27 and the Z-axis mass block 35. In design, the rigidity of the third collision limiting structure 31 is 10000-20000N/m, and is mainly used for absorbing impact events with impact peak value < = 20000G.

In order to avoid breakage of the beam structure due to excessive deformation stress in the worst case impact, such as a limit impact of up to 1000kg,1us, in the embodiment shown in fig. 3, a hard stop 34 is placed between the outer side of the Z-axis mass 35 and the stationary outer frame 33.

In the embodiment shown in fig. 3, the number of collision contact points 32 of the third collision limiting structure 31 is 8, and the collision contact points are distributed on the upper, lower, left and right sides of the Z-axis mass block 35; the number of hard limiters 34 is 2, and the hard limiters are distributed on the upper side and the lower side of the Z-axis mass block 35.

According to another aspect of the present invention, there is provided a single chip six axis sensor comprising: a gyroscope; according to the accelerometer provided by the invention, the packaging pressure of the accelerometer is 40-200 mBar.

In summary, the reliability of the Z-axis accelerometer in a low-pressure environment is improved through two ways, firstly, the air damping is increased through the air damping unit 23, so that the speed during collision and the occurrence frequency of collision are reduced, the possibility of collision debris is reduced, and the reliability of devices is improved; and then collision structures with different rigidities (such as a first collision limiting structure 22, a second collision limiting structure 27, a third collision limiting structure 31 and a hard limiter 34) are sequentially collided with the Z-axis mass block 35, so that the stress on the structure in the collision process is reduced. Therefore, the Z-axis accelerometer provided by the invention can normally work under the condition of lower packaging pressure of 40 mBar-200 mBar, and the extra requirement of the single-chip six-axis sensor on the packaging pressure of the packaging process is reduced by improving the reliability of the accelerometer in low vacuum degree, so that the production cost is further reduced.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications and alternatives to the above embodiments may be made by those skilled in the art within the scope of the invention.

Claims

1. An accelerometer, comprising a Z-axis accelerometer capable of sensing a Z-axis acceleration, the Z-axis accelerometer comprising:

a Z-axis mass defining a first space and a second space therein;

an anchor point structure located within the first space;

the rotating shaft is positioned in the first space and is parallel to the X or Y axis, the rotating shaft is connected with the anchor point structure and the Z-axis mass block, the mass of the Z-axis mass block positioned on one side of the rotating shaft is different from the mass of the Z-axis mass block positioned on the other side of the rotating shaft, and the Z-axis mass block can perform seesaw type movement by taking the rotating shaft as an axis;

the air damping unit is positioned in the second space and comprises 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, wherein the fixed damping comb teeth and the movable damping comb teeth are distributed in an interdigital manner to form a plurality of air damping pairs;

wherein the X-axis and the Y-axis are perpendicular to each other and define a plane in which the substrate of the Z-accelerometer lies, and the Z-axis is perpendicular to the plane defined by the X-axis and the Y-axis.

2. The accelerometer of claim 1, wherein the accelerometer is configured to,

the Z-axis accelerometer further includes a first Z-axis sense electrode and a second Z-axis sense electrode,

the first Z-axis detection electrode and the second Z-axis detection electrode are positioned below the Z-axis mass block and are arranged on two sides of the rotating shaft;

when the Z-axis acceleration input is sensed, the Z-axis mass block can be enabled to move in a teeterboard mode by taking the rotating shaft as an axis, the first Z-axis detection electrode detects the distance change between the Z-axis mass block and the second Z-axis detection electrode detects the distance change between the Z-axis mass block and the first Z-axis detection electrode.

3. The accelerometer of claim 1, wherein the accelerometer is configured to,

the air damping units are distributed adjacent to the rotating shaft, the fixed damping comb teeth and the movable damping comb teeth are parallel to the rotating shaft,

the air damping units are four, wherein two air damping units are positioned at one side of the anchor point structure in the X-axis direction and are respectively positioned at two sides of the rotating shaft in the Y-axis direction; the other two air damping units are positioned on the other side of the anchor point structure in the X-axis direction and are respectively positioned on the two sides of the rotating shaft in the Y-axis direction;

the four air damping units are symmetrically distributed on the X axis and the Y axis as a whole.

4. The accelerometer of claim 1, wherein the accelerometer is configured to,

the anchor point structure comprises a second anchor point, a buffer beam and a snake beam,

the buffer beam is connected with the second anchor point and the rotating shaft;

the snake-shaped beam is located at one side, far away from the rotating shaft, of the second anchor point, one end of the snake-shaped beam is connected with the second anchor point, and the other end of the snake-shaped beam is close to the Z-axis mass block.

5. The accelerometer of claim 4, wherein the accelerometer is configured to,

the other end of the serpentine beam, which is close to the Z-axis mass block, is provided with a first collision limiting structure;

the first collision limiting structure has descending distribution of the heights in the direction along the Y axis, which is close to the Z-axis mass block, and the top end of the first collision limiting structure is circular.

6. The accelerometer of claim 4, wherein the accelerometer is configured to,

the anchor point structures are two and distributed on two sides of the Y-axis direction of the rotating shaft;

the two anchor structures are symmetrically distributed about the X-axis.

7. The accelerometer of claim 4, wherein the accelerometer is configured to,

a third space is also defined in the Z-axis mass block,

the Z-axis accelerometer further comprises a second collision limiting structure positioned in the third space, which can simultaneously inhibit the impact in the X/Y direction,

the second collision limiting structure comprises a third anchor point and a plurality of cantilever structures positioned outside the third anchor point, one end of each cantilever structure is fixed on the third anchor point, and the other end of each cantilever structure is close to the Z-axis mass block.

8. The accelerometer of claim 7, wherein the accelerometer is configured to,

the cantilever beam structure is a Z-shaped right-angle structure;

the cantilever beam structures are four and are respectively positioned on four sides of the third anchor point.

9. The accelerometer of claim 7, wherein the accelerometer is configured to,

the Z-axis accelerometer further comprises:

the Z-axis mass block is surrounded by the fixed outer frame;

and the third collision limiting structure is arranged between the periphery of the outer side of the Z-axis mass block and the fixed outer frame.

10. The accelerometer of claim 9, wherein the accelerometer is configured to,

the Z-axis accelerometer also includes a hard stop,

the hard limiter is arranged between the outer side of the Z-axis mass block and the fixed outer frame.

11. The accelerometer of claim 9, wherein the accelerometer is configured to,

the collision distance between the second collision limiting structure and the Z-axis mass block is larger than that 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 that between the second collision limiting structure and the Z-axis mass block.

12. The accelerometer of claim 9, wherein the accelerometer is configured to,

the collision distance between the first collision structure and the Z-axis mass block is designed to be 1.4-2.5 um, and the rigidity is as follows: 500-2000N/m;

the collision distance between the second collision structure and the Z-axis mass block is 0.2-0.5 um larger than that between the first collision limit structure and the Z-axis mass block; the rigidity is as follows: 2000-4000N/m;

the collision distance between the third collision limiting structure and the fixed outer frame is 0.5-0.8 um larger than that between the first collision limiting structure and the Z-axis mass block, and the rigidity is as follows: 10000-20000N/m.

13. A single chip six axis sensor, comprising:

a gyroscope;

an accelerometer according to any of claims 1-12.

14. The accelerometer of claim 13, wherein the accelerometer has a package pressure of 40mBar to 200mBar.