CN216595182U

CN216595182U - Z-axis accelerometer

Info

Publication number: CN216595182U
Application number: CN202121928408.7U
Authority: CN
Inventors: 凌方舟; 丁希聪; 蒋乐跃; 刘尧
Original assignee: Memsic Semiconductor Wuxi Co Ltd
Current assignee: Memsic Semiconductor Wuxi Co Ltd
Priority date: 2021-08-17
Filing date: 2021-08-17
Publication date: 2022-05-24
Anticipated expiration: 2031-08-17

Abstract

The utility model provides a Z-axis accelerometer, comprising: a substrate; and the mass block is suspended above the substrate and is divided into a first area and a second area by a boundary line, wherein the first area and the second area of the mass block are symmetrically distributed around the boundary line, and the thicknesses of the first area and the second area of the mass block are different, so that the masses of the first area and the second area of the mass block are different, and the mass block generates seesaw-like motion by taking the boundary line as an axis. Compared with the prior art, the utility model not only effectively saves the chip area and reduces the cost, but also greatly improves the external interference resistance, thereby improving the Z-axis detection precision.

Description

Z-axis accelerometer

[ technical field ] A

The utility model relates to the technical field of micro-mechanical systems, in particular to a Z-axis accelerometer based on a surface silicon process.

[ background ] A method for producing a semiconductor device

A Micro-electromechanical accelerometer is an inertial device based on MEMS (Micro-Electro-Mechanical systems) technology, and is used to measure linear motion acceleration of an object motion. The novel high-voltage switch has the characteristics of small volume, high reliability, low cost, suitability for mass production and the like, so that the novel high-voltage switch has a wide market prospect, and the application fields of the novel high-voltage switch comprise consumer electronics, aerospace, automobiles, medical equipment, weapons and the like. However, the accelerometer in the prior art has the problems of large occupied chip area and poor external interference resistance.

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

[ Utility model ] A method for manufacturing a semiconductor device

One of the objectives of the present invention is to provide a Z-axis accelerometer, which not only effectively saves chip area and reduces cost, but also greatly improves the external interference resistance, thereby improving the Z-axis detection accuracy.

According to one aspect of the utility model, there is provided a Z-axis accelerometer comprising:

a substrate;

and the mass block is suspended above the substrate and is divided into a first area and a second area by a boundary line, wherein the first area and the second area of the mass block are symmetrically distributed around the boundary line, and the thicknesses of the first area and the second area of the mass block are different, so that the masses of the first area and the second area of the mass block are different, and the mass block generates seesaw-like motion by taking the boundary line as an axis.

Compared with the prior art, the Z-axis accelerometer provided by the utility model has the advantages that the first area and the second area of the mass block are completely symmetrical about the boundary line; the thickness of the first area and the thickness of the second area of the mass block are different through a sacrificial layer process by adopting a surface silicon technology, so that the mass of the first area and the mass of the second area of the mass block are different, and the symmetrical and unequal mass of the Z-axis accelerometer is further realized. Therefore, the Z-axis accelerometer designed by the utility model is symmetrically distributed, so that the external interference resistance is greatly improved, the Z-axis detection precision is further improved, the chip area is effectively saved, and the cost is reduced.

[ description of the drawings ]

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:

FIG. 1 is a schematic diagram of the overall structure of a Z-axis accelerometer according to a first embodiment of the utility model;

FIG. 2 is a schematic cross-sectional view of the Z-axis accelerometer shown in FIG. 1 taken along B-B in one embodiment of the utility model;

FIG. 3 is a schematic cross-sectional view of the Z-axis accelerometer of FIG. 1 taken along B-B in another embodiment of the present invention;

FIG. 4 is a schematic cross-sectional view of a Z-axis accelerometer taken along line B-B in a second embodiment of the utility model;

FIG. 5 is a schematic cross-sectional view of a Z-axis accelerometer taken along B-B in a third embodiment of the utility model;

FIG. 6 is a schematic cross-sectional view taken along B-B of a Z-axis accelerometer of a fourth embodiment of the utility model;

figure 7 is a schematic cross-sectional view of a Z-axis accelerometer taken along B-B in a fifth embodiment of the utility model.

Wherein, 1-mass block; 1 a-a first region of mass; 1 b-a second region of mass; 2-anchor point; 3 a-a first torsion beam; 3 b-a second twist beam; 4 a-a first sensing electrode; 4 b-a second sensing electrode; 5-a substrate; the central axis of the AA-Y axis; a central axis of BB-X axis; 6-a first space; 7-a through hole; 8-blind holes; 9-a groove; 10-opening.

[ detailed description ] embodiments

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

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 utility model. 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 otherwise specified, the terms connected, and connected as used herein mean electrically connected, directly or indirectly.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in 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, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," "coupled," and the like are to be construed broadly; for example, the connection can be fixed, detachable or integrated; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other suitable relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Aiming at the problems in the prior art, the utility model provides a Z-axis accelerometer. Fig. 1 is a schematic view of an overall structure of a Z-axis accelerometer according to a first embodiment of the utility model; FIG. 2 is a cross-sectional view of the Z-axis accelerometer shown in FIG. 1 taken along line B-B according to an embodiment of the utility model. Referring to FIG. 3, a cross-sectional view of the Z-axis accelerometer of FIG. 1 taken along B-B is shown in another embodiment of the present invention. The Z-axis accelerometer shown in figures 1, 2 and 3 comprises a proof mass 1 and a substrate 5. The mass block 1 is suspended above the substrate 5, the mass block 1 is divided into a first area 1a and a second area 1b by a boundary A-A, and the masses of the first area 1a and the second area 1b of the mass block 1 are different, so that the mass block 1 generates seesaw-like motion by taking the boundary A-A as an axis.

To better illustrate the structure of the Z-axis accelerometer of the present invention, a three-dimensional rectangular coordinate system can be established, in the embodiment shown in fig. 1, the X-axis and the Y-axis are perpendicular to each other and define the plane of the substrate 1 of the Z-axis accelerometer, 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 represented in fig. 1, wherein the X-axis is along the left-right direction, the Y-axis is along the up-down direction, and the Z-axis is along the direction perpendicular to the paper.

In the embodiment shown in fig. 1, 2 and 3, the first area 1a and the second area 1B of the mass 1 are completely symmetrical about the dividing line a-a (or the mass 1 is completely symmetrical about the dividing line a-a), where a-a is a Y-axis central axis of the mass 1 and B-B is an X-axis central axis of the mass 1; according to the utility model, a surface silicon technology is adopted, and the thicknesses of the first region 1a and the second region 1b of the mass block 1 are different through a sacrificial layer process (for example, etching after sacrificial layer deposition), so that the masses of the first region 1a and the second region 1b of the mass block 1 are different, and further the symmetrical and unequal masses of the Z-axis accelerometer are realized. The Z-axis accelerometer designed by the utility model is symmetrically distributed, so that the external interference resistance is greatly improved, the Z-axis detection precision is further improved, the chip area is effectively saved, and the cost is reduced.

It is to be noted in particular that the first region 1a and the second region 1b of the mass 1 are completely symmetrical with respect to the dividing line a-a. The perfect symmetry here means that the frame shape of the first area 1a and the frame shape of the second area 1b are symmetrical regardless of whether other structures are provided in the first area 1a and the second area 1 b. When the frame shape of the first region 1a and the frame shape of the second region 1b are symmetrical with respect to the boundary a-a, the phenomenon that the charge distribution is asymmetrical at the edges of the first region 1a and the second region 1b can be avoided, and the reliability of the device can be improved.

In the embodiment shown in fig. 2, the thickness of the second region 1b of the mass 1 is greater than the thickness of the first region 1a, so that the mass of the second region 1b of the mass 1 is greater than the mass of the first region 1 a. In the embodiment shown in fig. 3, the thickness of the second region 1b of the mass 1 is smaller than the thickness of the first region 1a, so that the mass of the second region 1b of the mass 1 is smaller than the mass of the first region 1 a.

In the embodiment shown in fig. 1, 2 and 3, the Z-axis accelerometer further includes a first sensitive electrode 4a and a second sensitive electrode 4b, and the first sensitive electrode 4a and the second sensitive electrode 4b are respectively disposed below the first region 1a and the second region 1b of the proof mass 1 and symmetrically disposed on two sides of the dividing line a-a. When the input of the Z-axis acceleration is sensed, the mass block 1 is enabled to be twisted or pivoted (or perform seesaw-like motion) by taking the boundary line a-a as an axis, the first sensitive electrode 4a detects the change of the distance from the first area 1a of the mass block 1, the second sensitive electrode 4b detects the change of the distance from the second area 1b of the mass block 1, specifically, after the Z-axis acceleration rate is sensed, the capacitance of the first sensitive electrode 4a and the capacitance of the second sensitive electrode 4b are increased and decreased, the difference between the two is used for obtaining the capacitance change caused by the Z-axis acceleration, and further obtaining the magnitude of the input Z-axis acceleration rate. It should be noted that, when the Z-axis acceleration input is not sensed, the distance between the first sensing electrode 4a and the first region 1a of the proof mass 1 directly above the first sensing electrode is equal to the distance between the second sensing electrode 4b and the second region 1b of the proof mass 1 directly above the second sensing electrode 4a, so as to ensure that the capacitance signal of the first sensing electrode 4a and the capacitance signal of the second sensing electrode 4b are different.

In the embodiment shown in figures 1, 2 and 3, the Z-axis accelerometer further comprises an anchor point 2 and

torsion beams

3a, 3 b; a first space 6 is defined in the mass block 1, and the anchor point 2 and the

torsion beams

3a and 3b are arranged in the first space 6; the

torsion beams

3a, 3b connect the anchor point 2 and the mass 1. The mass of the first area 1a and the mass of the second area 1b of the mass block 1 are different, so that the mass block 1 generates seesaw-like motion by taking the

torsion beams

3a and 3b as axes.

In the specific embodiment shown in fig. 1, 2 and 3, the anchor point 2 is located at the center point of the mass 1; the number of the

torsion beams

3a and 3b is two, and the torsion beams are respectively a first torsion beam 3a and a second torsion beam 3b, wherein the first torsion beam 3a and the second torsion beam 3b are positioned on the upper side and the lower side of the anchor point 2 and are arranged along a boundary line A-A; the first torsion beam 3a and the second torsion beam 3b are both connected to the anchor point 2 and the mass 1. The proof-mass 1 is supported by the

beam structures

3a, 3b and the anchor point 2 such that the proof-mass 1 is suspended above the substrate 5.

In the particular embodiment shown in fig. 1, 2 and 3, the anchor points 2 are fixedly arranged on the substrate 5; the first sensitive electrode 4a and the second sensitive electrode 4b are fixedly arranged on the substrate 5; the mass 1 and the

torsion beams

3a, 3b are suspended above the substrate 5; the first torsion beam 3a and the second torsion beam 3b are symmetrically distributed about the X-axis, or the first torsion beam 3a and the second torsion beam 3b are arranged along the dividing line a-a and symmetrically distributed about the anchor point 2.

Please refer to fig. 4, which is a cross-sectional view of a Z-axis accelerometer along B-B according to a second embodiment of the utility model. The structure of the Z-axis accelerometer shown in fig. 4 is substantially identical to the structure of the Z-axis accelerometer shown in fig. 1 and 2, and the main difference is that a through hole 7 is further provided in the first region 1a of the mass 1 of the Z-axis accelerometer of fig. 4. That is, the Z-axis accelerometer shown in fig. 4 not only makes the thicknesses of the first region 1a and the second region 1b of the proof mass 1 inconsistent through the sacrificial layer process, but also can make the masses of the first region 1a and the second region 1b of the proof mass 1 different by providing a plurality of through holes 7 in the first region 1a and/or the second region 1b of the proof mass 1.

FIG. 5 is a cross-sectional view taken along line B-B of a Z-axis accelerometer according to a third embodiment of the utility model. The structure of the Z-axis accelerometer shown in fig. 5 is substantially identical to the structure of the Z-axis accelerometer shown in fig. 1 and 2, and the main difference is that the first region 1a of the mass 1 of the Z-axis accelerometer of fig. 5 is further provided with a blind hole 8. That is, the Z-axis accelerometer shown in fig. 5 not only makes the thicknesses of the first region 1a and the second region 1b of the proof mass 1 inconsistent through the sacrificial layer process, but also can make the masses of the first region 1a and the second region 1b of the proof mass 1 different by providing a plurality of blind holes 8 in the first region 1a and/or the second region 1b of the proof mass 1. In one embodiment, material may be added inside or above the through holes 7 and the blind holes 8 of the mass 1, so that the first area 1a and the second area 1b have different masses.

FIG. 6 is a cross-sectional view taken along line B-B of a Z-axis accelerometer according to a fourth embodiment of the utility model. The structure of the Z-axis accelerometer shown in fig. 6 is substantially the same as that of the Z-axis accelerometer shown in fig. 1 and 2, and the main difference is that the Z-axis accelerometer of fig. 6 is subjected to large-area etching on the first region 1a of the mass block 1 to form a groove 9 (or a semi-hollow structure 9). That is, the Z-axis accelerometer shown in fig. 6 not only makes the thicknesses of the first region 1a and the second region 1b of the proof mass 1 inconsistent through the sacrificial layer process, but also makes the masses of the first region 1a and the second region 1b of the proof mass 1 different by performing large-area etching on a single-sided region (i.e., within the first region 1a or the second region 1 b) of the proof mass 1 to form the recess 9.

FIG. 7 is a cross-sectional view taken along line B-B of a Z-axis accelerometer according to a fifth embodiment of the utility model. The structure of the Z-axis accelerometer shown in figure 7 is substantially identical to that of the Z-axis accelerometer shown in figures 1 and 2, with the main difference that the Z-axis accelerometer of figure 7 has a large area etched into the first region 1a of the mass 1 to form an opening 10 therethrough. That is, the Z-axis accelerometer shown in fig. 7 not only makes the thicknesses of the first region 1a and the second region 1b of the proof mass 1 inconsistent through the sacrificial layer process, but also can make the masses of the first region 1a and the second region 1b of the proof mass 1 different by performing large-area etching on a single-side region (i.e., in the first region 1a or the second region 1 b) of the proof mass 1 to form through openings 10 (or hollow structures 10).

In summary, the present invention provides a Z-axis accelerometer, which includes: a substrate 5; a mass 1 suspended above the substrate 5, the mass 1 being divided into a first region 1a and a second region 1b by a boundary line, the first region 1a and the second region 1b of the mass 1 being symmetrically distributed about the boundary line a-a; according to the utility model, a surface silicon technology is adopted, and the thicknesses of the first region 1a and the second region 1b of the mass block 1 are different through a sacrificial layer process, so that the masses of the first region 1a and the second region 1b of the mass block 1 are different, and further the symmetrical and unequal masses of the Z-axis accelerometer are realized. The Z-axis accelerometer designed by the utility model is symmetrically distributed, so that the external interference resistance is greatly improved, the Z-axis detection precision is further improved, the chip area is effectively saved, and the cost is reduced.

In addition, the sensitivity of the Z-axis accelerometer extended by the frame (mass block) is high under the same area.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example" or "some examples" or the like are intended to mean 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 utility model. In this specification, the schematic representations of the terms used above are not necessarily intended to refer 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. Furthermore, various embodiments or examples described in this specification can be combined and combined by one skilled in the art.

While embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that changes, modifications and variations may be made therein by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A Z-axis accelerometer, comprising:

a substrate;

2. The Z-axis accelerometer of claim 1,

the thickness of a partial area of the second area of the mass block is larger than that of the first area; or

The thickness of the partial area of the second area of the mass block is smaller than that of the first area.

3. The Z-axis accelerometer of claim 1, further comprising first and second sensing electrodes disposed below the first and second regions of the proof mass, respectively, and symmetrically disposed on either side of the dividing line.

4. The Z-axis accelerometer of claim 3,

it also includes anchor points and torsion beams;

a first space is defined in the mass block, and the anchor point and the torsion beam are arranged in the first space;

the torsion beam is connected with the anchor point and the mass block;

the mass of the first area and the mass of the second area of the mass block are different, so that the mass block generates seesaw-like motion by taking the torsion beam as an axis.

5. The Z-axis accelerometer of claim 4,

the number of the torsion beams is two, namely a first torsion beam and a second torsion beam,

the first torsion beam and the second torsion beam are positioned on two sides of the anchor point and are arranged along the boundary line;

the first torsion beam and the second torsion beam are connected with the anchor point and the mass block.

6. The Z-axis accelerometer of claim 5,

the anchor points are fixedly arranged on the substrate;

the first sensitive electrode and the second sensitive electrode are fixedly arranged on the substrate;

the mass block and the torsion beam are suspended above the substrate;

the first and second twist beams are disposed along the dividing line and symmetrically distributed about the anchor point.

7. The Z-axis accelerometer of claim 1,

a through hole is formed in the first area or the second area of the mass block; or

And a blind hole is arranged in the first area or the second area of the mass block.

8. The Z-axis accelerometer of claim 7,

and materials are added in or above the through holes or the blind holes, so that the quality of the first area is different from that of the second area.

9. The Z-axis accelerometer of claim 1,

etching the first region or the second region of the mass block to form a groove; or

The first region or the second region of the proof mass is etched to form a through opening.

10. The Z-axis accelerometer of claim 3,

when the input of Z-axis acceleration is not sensed, the distance between the first sensing electrode and the first area right above the first sensing electrode is equal to the distance between the second sensing electrode and the second area right above the second sensing electrode.