KR102528214B1 - 3-axis MEMS acceleration sensor based on single mass - Google Patents

Abstract

A three-axis MEMS acceleration sensor based on a single mass is disclosed.
A three-axis MEMS acceleration sensor based on a single mass according to an embodiment of the present invention uses capacitance change between a single mass body integrally formed and supported by a substrate and an electrode provided on the substrate to measure the X-axis, Y-axis and An acceleration sensor for sensing acceleration in the Z-axis direction, wherein the mass body includes: a first side plate located in the -X region, a second side plate located in the +X region, and a first plate structure having a connecting plate portion connecting an end portion of the first side plate portion in the +Y direction and an end portion of the second side plate portion in the +Y direction; A center plate portion located in the center region surrounded by the first side plate portion, the second side plate portion, and the connecting plate portion of the first plate structure, and an extension plate portion extending from the end of the center plate portion in the -Y direction but extending outside the center region. A second plate structure having a; and integrally formed and located in the central region, but located between the first plate structure and the second plate structure, so that one part is integrally connected to the first plate structure and the other part is integrally connected to the second plate structure. It includes a composite elastic structure connected to.

Description

3-axis MEMS acceleration sensor based on single mass}

The present invention relates to a single-mass-based 3-axis MEMS acceleration sensor, and more particularly, to a single-mass-based accelerometer that senses accelerations in the X-, Y-, and Z-axis directions using a single integrally formed mass. It is about a 3-axis MEMS accelerometer.

In general, MEMS (Micro Electro Mechanical Systems) refers to a system combining an integrated circuit and a micromechanical structure. Recently, with the development of semiconductor manufacturing technology and SoC (System on Chip) technology, a number of MEMS acceleration sensors for sensing acceleration using the MEMS have been introduced.

However, as disclosed in Korean Patent Registration No. 10-1184549, the existing technology is a plurality of masses (FIG. 4, Since 110 and 110' in FIG. 7 are used, there is a problem in that miniaturization and weight reduction of the acceleration sensor are difficult and manufacturing cost is increased.

In addition, as disclosed in Korean Patent Registration No. 10-1697828, in the existing technology, since springs of different structures that move the mass body in various directions are independently configured and asymmetrically distributed based on the mass body, the acceleration The complexity of the sensor increases, and when acceleration occurs, unintended torque or deformation occurs in the mechanical structure of the acceleration sensor, thereby degrading the accuracy of the acceleration measurement result.

The technical problem to be solved by the present invention is a single-mass-based 3-axis MEMS acceleration sensor that measures acceleration in all 3-axis directions, while miniaturization and weight are easy, manufacturing cost is reduced, and the accuracy and reliability of the acceleration measurement result are improved. is to provide

A three-axis MEMS acceleration sensor based on a single mass according to an embodiment of the present invention uses capacitance change between a single mass body integrally formed and supported by a substrate and an electrode provided on the substrate to measure the X-axis, Y-axis and An acceleration sensor for sensing acceleration in the Z-axis direction, wherein the mass body includes: a first side plate located in the -X region, a second side plate located in the +X region, and a first plate structure having a connecting plate portion connecting an end portion of the first side plate portion in the +Y direction and an end portion of the second side plate portion in the +Y direction; A center plate portion located in the center region surrounded by the first side plate portion, the second side plate portion, and the connecting plate portion of the first plate structure, and an extension plate portion extending from the end of the center plate portion in the -Y direction but extending outside the center region. A second plate structure having a; and integrally formed and located in the central region, but located between the first plate structure and the second plate structure, so that one part is integrally connected to the first plate structure and the other part is integrally connected to the second plate structure. The composite elastic structure is elastically deformed in a first pattern when acceleration in the X-axis direction occurs, and the first plate structure and the second plate structure are translated together in a first direction, and , When acceleration in the Y-axis direction is elastically deformed in a second pattern, the first plate structure and the second plate structure are translated together in the second direction, and when acceleration in the Z-axis direction is elastically deformed in a third pattern It is configured to rotate only the second plate structure around the X-axis.

In one embodiment, the composite elastic structure, a fixing portion fixed to the substrate; a first elastic body unit having an elastic deformation structure that expands and contracts in the Y-axis direction and integrally connected to the fixing unit; a second elastic body unit having an elastically deformable structure that expands and contracts in the X-axis direction and integrally connected to the first elastic body unit; a connecting beam part having one part integrally connected to the second elastic body part and the other part integrally connected to the first plate structure to support the first plate structure; and extending along the X axis, one end integrally connected to the connecting beam portion and the other end integrally connected to the central plate portion of the second plate structure to support the second plate structure, clockwise about the X axis. Alternatively, it may include a torsion beam portion capable of elastic deformation twisted in a counterclockwise direction.

In one embodiment, the first elastic body part includes a beam structure extending in a zigzag or meander form along the Y-axis direction as an elastically deformable structure that expands and contracts in the Y-axis direction, and the 2 The elastic body unit may include a ring-shaped beam structure as an elastic deformation structure that expands and contracts in the X-axis direction.

In one embodiment, the connecting beam unit has a predetermined width and extends in parallel with the Y-axis, the first connecting beam unit integrally connected to the one end of the torsion beam unit; a second connecting beam part having a predetermined width and extending from the first connecting beam part and integrally connected to the first plate structure; and a third connecting beam portion having a predetermined width and extending from the first connecting beam portion or the second connecting beam portion and integrally connected to the second elastic body portion, wherein the first connecting beam portion is connected to the torsion beam portion, It may be configured with a wider width than the second connecting beam part and the third connecting beam part.

In one embodiment, the center plate portion of the second plate structure and the composite elastic structure each have an X-axis symmetric structure, and the extension plate portion of the second plate structure is based on the origin of the second plate structure. It may be configured to have a mass that locates the center of gravity of the -Y region and places the center of gravity of the entire mass on the X axis.

In one embodiment, the central plate portion of the second plate structure has a structure that is symmetrical to the X-axis and symmetrical to the Y-axis, and the extension plate portions of the first plate structure and the second plate structure are each symmetrical to the Y-axis. A first composite elastic structure positioned between the first side plate portion of the first plate structure and the center plate portion of the second plate structure; and a second composite elastic structure positioned between the second side plate portion of the first plate structure and the center plate portion of the second plate structure and having a structure symmetrical to the first composite elastic structure with respect to the Y-axis. there is.

According to the present invention, a MEMS structure capable of measuring all accelerations in the X-, Y-, and Z-axis directions using only a single mass body formed integrally is provided, thereby facilitating miniaturization and lightening of the three-axis acceleration sensor and manufacturing You can cut costs.

In addition, the mass body located on the XY plane includes a first plate structure, a second plate structure, and a composite elastic structure integrally connected to each other, and the composite elastic structure corresponds to acceleration in the X-axis, Y-axis, and Z-axis directions, respectively to be elastically deformed but elastically deformed in different patterns according to the direction of acceleration, so that the first plate structure and the second plate structure are translated together on the XY plane or only the second plate structure is rotated around the X axis As a result, space utilization of the mass body may be increased and complexity of the 3-axis acceleration sensor may be reduced.

In addition, the first plate structure, the second plate structure, and the composite elastic structure of the mass body are configured in different shapes, and the +Y area portion and -Y area portion of the mass body are mutually related to each other based on the origin located at the center of the mass body. Since the +X area portion and -X area portion of the mass body are configured to have the same mass and have the same mass based on the origin, torque unintended to the mass body when acceleration in the X-axis direction or Y-axis direction occurs. It is possible to prevent deformation and improve the accuracy and reliability of acceleration measurement results.

Furthermore, those skilled in the art to which the present invention belongs will be able to clearly understand from the following description that various embodiments according to the present invention can solve various technical problems not mentioned above.

1 is a plan view illustrating a 3-axis MEMS acceleration sensor according to an embodiment of the present invention.
FIG. 2 is a vertical cross-sectional view of the 3-axis MEMS acceleration sensor shown in FIG. 1 taken along line AA'.
FIG. 3 is a view showing a composite elastic structure of the mass shown in FIG. 1 .
FIG. 4 is a view showing elastic deformation patterns according to acceleration in the X-axis direction of the composite elastic structure shown in FIG. 3 .
5 is a view showing elastic deformation patterns according to acceleration in the Y-axis direction of the composite elastic structure shown in FIG. 3 .
6 is a view showing a composite elastic structure according to another embodiment of the present invention.
FIG. 7 is a vertical cross-sectional view of the 3-axis MEMS acceleration sensor shown in FIG. 1 taken along line BB'.
FIG. 8 is a view showing an elastic deformation pattern according to acceleration in the Z-axis direction of the mass body shown in FIG. 7 .

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to clarify solutions to the technical problems of the present invention. However, in the description of the present invention, if the description of the related known technology makes the gist of the present invention unclear, the description thereof will be omitted. In addition, the terms used in this specification are terms defined in consideration of functions in the present invention, and they may vary according to the intention or custom of a designer or manufacturer. Therefore, the definitions of the terms to be described below will have to be made based on the content throughout this specification.

1 shows a three-axis MEMS acceleration sensor 10 according to an embodiment of the present invention in a plan view.

As shown in FIG. 1, the 3-axis MEMS acceleration sensor 10 according to an embodiment of the present invention includes a single mass body 200 integrally formed and supported by a substrate 100, and the substrate 100 It is configured to sense all accelerations in the X-axis, Y-axis, and Z-axis directions by using capacitance change between the electrodes 102 and 104 provided on ).

To this end, the mass body 200 may include a first plate structure 210, a second plate structure 220, and a composite elastic structure 230 integrally connected to each other and positioned on the XY plane.

The first plate structure 210 may have a plate shape having a certain thickness and having one side edge concave toward the center. For example, the first plate structure 210 includes a first side plate part 212 located in the -X region and a second side plate part located in the +X region based on the origin O, which is the intersection of the X and Y axes 214), and a connection plate portion 216 connecting the +Y direction end of the first side plate portion 212 and the +Y direction end of the second side plate portion 214.

The second plate structure 220 has a predetermined thickness and is molded in a central region surrounded by the first side plate portion 212, the second side plate portion 214, and the connection plate portion 216 of the first plate structure 210 as a whole. It can be configured in the form of a combined plate. For example, the second plate structure 220 includes a center plate portion 222 positioned in a central area surrounded by the first side plate portion 212 , the second side plate portion 214 , and the connection plate portion 216 of the first plate structure 210 . ), and an extension plate portion 224 extending from the end of the center plate portion 222 in the -Y direction and extending to the outside of the center region.

The composite elastic structure 230 is formed integrally and is located in the central region, but is located between the first plate structure 210 and the second plate structure 220, so that a portion of the first plate structure 210 and integrally connected, and the other part may be integrally connected with the second plate structure 220 .

As will be described later, the composite elastic structure 230 is elastically deformed in a first pattern when acceleration in the X-axis direction occurs, and the first plate structure 210 and the second plate structure 220 are translated together in the first direction. When acceleration in the Y-axis direction occurs, it is elastically deformed in a second pattern to translate the first plate structure 210 and the second plate structure 220 together in the second direction, and when acceleration in the Z-axis direction occurs, the first plate structure 210 and the second plate structure 220 move It may be elastically deformed in three patterns to rotate only the second plate structure 220 around the X-axis.

These composite elastic structures 230 may be configured as a pair. That is, the composite elastic structure 230 may include a first composite elastic structure and a second composite elastic structure having mutually symmetric structures based on the Y-axis passing through the origin (O). In this case, the first composite elastic structure is located between the first side plate portion 212 of the first plate structure 210 and the center plate portion of the second plate structure 220, and the second composite elastic structure is the first composite elastic structure. It may be positioned between the second side plate portion 214 of the plate structure 210 and the center plate portion of the second plate structure 220 .

As described above, the mass body 200 is configured by integrally connecting the first plate structure 210, the second plate structure 220, and the composite elastic structure 230 having different shapes, but the mass body 200 Since the mass of the mass body 200 is configured to be symmetrically distributed with respect to the X-axis and Y-axis passing through the center of gravity, unintended torque or deformation when acceleration in the X-axis direction and Y-axis direction occurs ( deformation) can be prevented.

To this end, the center plate portion 222 of the second plate structure 220 and the composite elastic structure 230 may each have an X-axis symmetrical structure with respect to the X-axis passing through the origin (O). In addition, the extension plate portion 224 of the second plate structure 220 locates the center of gravity of the second plate structure 220 itself in the -Y region based on the origin (O), and the second plate structure 220 ) together with the first plate structure 210 and the composite elastic structure 230 may be configured to have a mass that positions the center of gravity of the entire mass body 200 on the X axis.

In this case, the first plate structure 210 and the second plate structure 220 are composed of plate structures having the same thickness, but the first plate structure portion is located in the +Y region with respect to the origin O. The sum of the area of and the area of the second plate structure portion located in the +Y region is equal to the sum of the area of the first plate structure portion located in the -Y region and the area of the second plate structure portion located in the -Y region can be configured. That is, of the total area of the first plate structure 210, the area of the +Y region of the first side plate part 212, the area of the +Y region of the second side plate part 214, and the area of the connection plate part 216 The sum of the areas of the +Y region of the center plate portion 222 out of the total area of the two-plate structure 220 is the area of the -Y region of the first side plate portion 212 out of the total area of the first plate structure 210 and The area of the -Y region of the second side plate 214 and the total area of the second plate structure 220 are equal to the sum of the area of the -Y region of the center plate 222 and the area of the extension plate 224 It can be.

In addition, the mass body 200 may be configured to have a rectangular or circular outline as a whole on the XY plane. In this case, the first plate structure 210 and the second plate structure 220 of the mass body 200 have the shortest distance from the origin O to the edge of the first plate structure 210 in the +Y direction, and the The shortest distance from the origin O to the edge of the second plate structure 220 in the -Y direction may be the same. As a result, torque generated in the mass body 200 due to acceleration in the X-axis direction can be minimized.

Furthermore, the center plate portion 222 of the second plate structure 220 may have a structure that is symmetrical to the X axis and symmetrical to the Y axis, respectively, with respect to the X axis and the Y axis passing through the origin O. In addition, the extension plate portion 224 of the first plate structure 210 and the second plate structure 220 may each have a Y-axis symmetrical structure with respect to the Y-axis. As a result, the center of gravity of the mass body 200 is located on the origin O, and the mass of the mass body 200 is symmetrically distributed with respect to the X axis and the Y axis passing through the center of gravity.

As such, the first plate structure 210, the second plate structure 220, and the composite elastic structure 230 of the mass body 200 are configured in different shapes, but the origin (located at the center of the mass body 200) O), the +Y area part and -Y area part of the mass body 200 have the same mass, and the +X area part and -X area part of the mass body 200 based on the origin (O) By being configured to have the same mass and a symmetrical structure, it is possible to prevent unintended torque or deformation from occurring in the mass body 200 when acceleration occurs in the Y-axis direction as well as the X-axis direction, and the acceleration measurement result accuracy and reliability can be improved.

Meanwhile, a plurality of electrode holes 202 and 204 in which the electrodes 102 and 104 provided on the substrate 100 are positioned in the inner space may be formed in the first plate structure 210 of the mass body 200. there is.

FIG. 2 is a vertical cross-sectional view of the 3-axis MEMS acceleration sensor 10 shown in FIG. 1 taken along line A-A'.

As shown in FIG. 2, the substrate 100 of the 3-axis MEMS acceleration sensor 10 includes a first electrode 102 for detecting a change in capacitance when acceleration in the X-axis direction occurs, and acceleration in the Y-axis direction A second electrode 104 for sensing a change in capacitance may be provided. The substrate 100 may be made of a material such as silicon, glass or crystal. Also, the electrodes 102 and 104 may be made of a conductive material such as doped polysilicon or metal. As will be described again below, a third electrode for detecting a change in capacitance when acceleration in the Z-axis direction is generated may be further provided on the substrate 100 .

The mass body 200 may be configured to be supported by the substrate 100 . To this end, a portion of the composite elastic structure 230 of the mass body 200 may be fixed to the substrate 100 . In this case, an insulating layer 110 made of an insulating material such as an oxide film, a nitride film, or a polymer resin film may be interposed between the portion of the composite elastic structure 230 fixed to the substrate 100 and the substrate 100. there is. The first plate structure 210 and the second plate structure 220 of the mass body 200 may be integrally connected to and supported by the composite elastic structure 230 . The mass body 200 may be made of a conductive material such as doped polysilicon or metal.

As mentioned above, the first electrode hole 202 and the second electrode hole 204 may be formed in the first plate structure 210 of the mass body 200 . In this case, the first electrode 102 may be positioned in the inner space of the first electrode hole 202 , and the second electrode 104 may be positioned in the inner space of the second electrode hole 204 .

The capacitance (C) between an electrode located inside the electrode hole of the mass body 200 and the mass body 200 may be calculated as in Equation 1 below.

[Equation 1]

Here, d is the distance between the inner surface of the electrode hole and the electrode surface facing each other, A is the width of the electrode surface, ε _r is the relative permittivity between the two surfaces, and ε _o is the permittivity of vacuum.

In addition, when acceleration in a specific direction occurs and the distance between the inner surface of the electrode hole and the electrode surface is changed from d to d+δ, the changed electrode capacitance (C′) can be calculated as in Equation 2 below.

[Equation 2]

Here, d+δ is the distance between the inner surface of the electrode hole and the electrode surface facing each other, A is the width of the electrode surface, ε _r is the relative permittivity between the two surfaces, and ε _o is the permittivity of vacuum.

As such, when elastic deformation occurs in the composite elastic structure 230 of the mass body 200 due to the inertial force acting on the mass body 200 when acceleration in the X-axis direction or Y-axis direction occurs, the inner surface of the electrode hole facing each other and The distance between the electrode surfaces is changed to change the capacitance between the two surfaces, and the corresponding acceleration can be sensed using the change in capacitance.

The 3-axis MEMS acceleration sensor 10 may be implemented by performing a deposition process, a photo process, an etching process, and the like on a silicon substrate.

FIG. 3 shows a composite elastic structure 230 of the mass body 200 shown in FIG. 1 .

As shown in FIG. 3 , the composite elastic structure 230 of the mass body 200 is elastically deformed in a first pattern when acceleration in the X-axis direction occurs, and the first plate structure 210 and the second plate structure 220 are formed. together in the first direction, and when acceleration in the Y-axis direction occurs, it is elastically deformed in a second pattern to translate the first plate structure 210 and the second plate structure 220 together in the second direction, Z When acceleration in the axial direction occurs, it is elastically deformed in a third pattern so that only the second plate structure 220 is rotated around the X axis passing through the origin (O).

To this end, the composite elastic structure 230 may include a fixing part 232, a first elastic body part 234, a second elastic body part 236, a connecting beam part 238 and a torsion beam part 239.

The fixing part 232 is configured to be fixed to and supported by the substrate 100 . As mentioned above, the insulating layer 110 may be interposed between the fixing part 232 and the substrate 100 . The fixing part 232 may have an X-axis symmetrical structure with respect to the X-axis passing through the origin (O).

The first elastic body part 234 may have an elastically deformable structure that expands and contracts in the Y-axis direction and may be integrally connected to the fixing part 232 . The first elastic body part 234 is an elastically deformable structure that expands and contracts in the Y-axis direction, and has a zigzag or meander along the Y-axis direction, such as a 'c', 'd', or 'Z' shape. ) may include a beam structure extending in the form. Here, the 'Y-axis direction' means a direction parallel to the extension direction of the Y-axis passing through the origin (O). In one embodiment, the first elastic body part 234 is a +Y-side elastic body part extending in the +Y direction from the +Y-direction end of the fixing part 232, and the -Y-direction end of the fixing part 232 It may include a -Y-side elastic body portion extending in the -Y direction and having an X-axis symmetrical structure with the +Y-side elastic body portion.

The second elastic body part 236 may have an elastically deformable structure that expands and contracts in the X-axis direction and may be integrally connected to the first elastic body part 234 . The second elastic body part 236 may include a ring-shaped beam structure as an elastically deformable structure that expands and contracts in the X-axis direction. Here, the 'X-axis direction' means a direction parallel to the extension direction of the X-axis passing through the origin (O).

One part of the connecting beam part 238 is integrally connected to the second elastic body part 236 and the other part is integrally connected to the first plate structure 210 to support the first plate structure 210. can be configured to

To this end, the connection beam unit 238 may include a first connection beam unit 238a, a second connection beam unit 238b, and a third connection beam unit 238c. The first connection beam part 238a has a certain width and extends in parallel with the Y-axis passing through the origin O, so as to be integrally connected to one end of the torsion beam part 239. The second connecting beam portion 238b has a predetermined width and extends from the first connecting beam portion 238a to be integrally connected to the first plate structure 210 . The third connection beam part 238c has a certain width and extends from the first connection beam part 238a or the second connection beam part 238b to be integrally connected to the second elastic body part 236 .

The torsion beam part 239 extends along the X-axis passing through the origin O, one end is integrally connected to the first connection beam part 238a of the connection beam part 238, and the other end thereof is connected to the second plate structure. It is integrally connected to the central plate portion 222 of 220 to support the second plate structure 220, and can be configured to allow elastic deformation twisted in a clockwise or counterclockwise direction about the X axis.

Meanwhile, the first connection beam part 238a of the connection beam part 238 connected to the torsion beam part 239 may have a wider width than the second connection beam part 238b or the third connection beam part 238c.

Specifically, in order to reduce the overall size of the composite elastic structure 230 as much as possible, it is necessary to minimize the width of the connecting beam part 238 within a range in which durability of the composite elastic structure 230 is guaranteed. This is because the connecting beam part 238 is not a part constituting an elastic deformable structure requiring high durability, but a part constituting a simple support structure.

However, it should be noted that, among the first to third connecting beam parts of the connecting beam part 238, the first connecting beam part 238a connected to the torsion beam part 239 is a second plate structure ( 220), the stress due to torsional deformation of the torsion beam part 239 is relatively greater than that of the second connection beam part 238b or the third connection beam part 238c. Therefore, the first connection beam part 238a of the connection beam parts 238 is formed with a wider width than the second connection beam part 238b or the third connection beam part 238c, thereby minimizing the size of the composite elastic structure 230 and Its durability can be improved.

FIG. 4 shows an elastic deformation pattern according to acceleration in the X-axis direction of the composite elastic structure 230 shown in FIG. 3 .

As shown in FIG. 4 , when acceleration in the X-axis direction occurs, the second elastic body portion 236 of the composite elastic structure 230 is mainly involved in elastic deformation of the composite elastic structure 230 .

That is, when acceleration in the -X direction occurs, as shown in FIG. It extends in the +X direction.

On the other hand, when acceleration in the +X direction occurs, as shown in FIG. It contracts in the -X direction.

FIG. 5 shows an elastic deformation pattern according to acceleration in the Y-axis direction of the composite elastic structure 230 shown in FIG. 3 .

As shown in FIG. 5 , when acceleration in the Y-axis direction occurs, the first elastic body portion 234 of the composite elastic structure 230 is mainly involved in the elastic deformation of the composite elastic structure 230 .

That is, when acceleration in the -Y direction occurs, as shown in FIG. The meander type beam structure is stretched or contracted in the +Y direction. For example, among the first elastic body parts 234, the +Y-side elastic body part connected to the +Y-direction end of the fixing part 232 extends in the +Y-direction, and the -Y-side elastic body connected to the -Y-direction end of the fixing part 232. The portion contracts in the +Y direction.

On the other hand, when acceleration in the +Y direction occurs, as shown in FIG. The meander type beam structure is stretched or contracted in the -Y direction. For example, among the first elastic body parts 234, the +Y-side elastic body part connected to the +Y-direction end of the fixing part 232 is contracted in the -Y-direction, and the -Y-side elastic body connected to the -Y-direction end of the fixing part 232 The portion extends in the -Y direction.

6 shows a composite elastic structure 230' according to another embodiment of the present invention.

As shown in FIG. 6, the composite elastic structure 230' according to another embodiment of the present invention includes a fixing part 232, a first elastic body part 234, a second elastic body part 236a, 236b, a connection A beam unit 238 and a torsion beam unit 239 may be included.

The fixing part 232, the first elastic body part 234, the connection beam part 238, and the torsion beam part 239 of the composite elastic structure 230' are the corresponding components of the composite elastic structure 230 shown in FIG. may be configured in the same way as

It should be noted that the second elastic body parts 236a and 236b of the composite elastic structure 230' are elastically deformable structures that expand and contract in the X-axis direction, each having a ring shape and a plurality of ring shapes connected in series to each other. that includes a beam structure. In this case, the movement range of the mass body 200 in the X-axis direction is increased, so that the sensitivity of the 3-axis MEMS acceleration sensor 10 to the acceleration in the X-axis direction can be improved.

FIG. 7 is a vertical cross-sectional view along line BB' of the 3-axis MEMS acceleration sensor 10 shown in FIG. 1 .

As shown in FIG. 7 , the substrate 100 of the 3-axis MEMS acceleration sensor 10 may be provided with a third electrode 106 for detecting a change in capacitance when acceleration in the Z-axis direction occurs. The third electrode 106 may be made of a conductive material such as doped polysilicon or metal. The third electrode 106 may be provided below the +Y direction end and below the -Y direction end of the second plate structure 220 , respectively.

The second plate structure 220 has a left-right asymmetric structure and mass with respect to the torsion beam part 239 of the composite elastic structure 230, and is connected to and supported by the corresponding torsion beam part 239. Accordingly, when acceleration in the Z-axis direction occurs, the second plate structure 220 rotates clockwise or counterclockwise around the torsion beam unit 239 by generating torque due to inertial force.

FIG. 8 shows an elastic deformation pattern according to acceleration in the Z-axis direction of the mass body 200 shown in FIG. 7 .

As shown in FIG. 8 , when acceleration in the Z-axis direction occurs, the torsion beam part 239 of the composite elastic structure 230 of the mass body 200 is involved in the elastic deformation of the mass body 200 .

That is, when acceleration in the +Z direction occurs, an inertial force in the -Z direction opposite to the acceleration direction acts on the second plate structure 220 as shown in FIG. 8(a). At this time, among the +Y direction end and the -Y direction end of the second plate structure 220, the extension plate portion 224 is located and a greater inertial force acts on the -Y direction end having a relatively greater mass. A clockwise torque is generated in the plate structure 220 . As a result, the second plate structure 220 is inclined to the right with the torsion beam part 239 of the composite elastic structure 230 as the center.

On the other hand, when acceleration in the -Z direction occurs, an inertial force in the +Z direction opposite to the acceleration direction acts on the second plate structure 220 as shown in FIG. 8(b). At this time, among the +Y direction end and the -Y direction end of the second plate structure 220, the extension plate portion 224 is located and a greater inertial force acts on the -Y direction end having a relatively greater mass. Counterclockwise torque is generated in the plate structure 220 . As a result, the second plate structure 220 is inclined to the left with the torsion beam part 239 of the composite elastic structure 230 as the center.

As such, when the second plate structure 220 of the mass body 200 is tilted by the inertial force acting on the mass body 200 when acceleration in the Z-axis direction occurs, the upper surface of the third electrode 106 facing each other and the second plate structure 220 are tilted. The distance between the bottom surfaces of the plate structure 220 is changed to change the capacitance between the two surfaces, and the corresponding acceleration can be sensed using the change in capacitance.

As described above, according to the present invention, a MEMS structure capable of measuring all accelerations in the X-, Y-, and Z-axis directions using only a single mass body formed integrally is provided, thereby reducing the size and weight of the three-axis acceleration sensor can facilitate and reduce manufacturing costs.

In addition, the mass body located on the XY plane includes a first plate structure, a second plate structure, and a composite elastic structure integrally connected to each other, and the composite elastic structure corresponds to acceleration in the X-axis, Y-axis, and Z-axis directions, respectively to be elastically deformed but elastically deformed in different patterns according to the direction of acceleration, so that the first plate structure and the second plate structure are translated together on the XY plane or only the second plate structure is rotated around the X axis As a result, space utilization of the mass body may be increased and complexity of the 3-axis acceleration sensor may be reduced.

In addition, the first plate structure, the second plate structure, and the composite elastic structure of the mass body are configured in different shapes, and the +Y area portion and -Y area portion of the mass body are mutually related to each other based on the origin located at the center of the mass body. Since the +X area portion and -X area portion of the mass body are configured to have the same mass and have the same mass based on the origin, torque unintended to the mass body when acceleration in the X-axis direction or Y-axis direction occurs. It is possible to prevent deformation and improve the accuracy and reliability of acceleration measurement results.

Furthermore, the embodiments according to the present invention can solve various technical problems other than those mentioned in this specification in the related art as well as in the related art.

So far, the present invention has been described with reference to specific examples. However, those skilled in the art will clearly understand that various modified embodiments can be implemented within the technical scope of the present invention. Therefore, the embodiments disclosed above should be considered from a descriptive point of view rather than a limiting point of view. That is, the scope of the true technical idea of the present invention is shown in the claims, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

100: substrate 200: mass body
210: first plate structure 212: first side plate portion
214: second side plate part 216: connection plate part
220: second plate structure 222: center plate portion
224: extension plate 230: composite elastic structure
232: fixing part 234: first elastic body part
236: second elastic body part 238: connecting beam part
239: torsion beam unit

Claims (6)

In a 3-axis MEMS acceleration sensor based on a single mass that senses acceleration in the X-, Y-, and Z-axis directions by using capacitance change between a single mass body integrally formed and supported by a substrate and an electrode provided on the substrate ,
The mass body,
Based on the origin, which is the intersection of the X and Y axes, the first side plate located in the -X region, the second side plate located in the +X region, and the +Y direction end of the first side plate and the second side plate + a first plate structure having connecting plate portions connecting ends in the Y direction;
A center plate portion located in the center region surrounded by the first side plate portion, the second side plate portion, and the connecting plate portion of the first plate structure, and an extension plate portion extending from the end of the center plate portion in the -Y direction but extending outside the center region. A second plate structure having a; and
It is integrally formed and located in the central region, but is located between the first plate structure and the second plate structure, so that one part is integrally connected to the first plate structure and the other part is integrally connected to the second plate structure. Including a complex elastic structure that is connected,
The composite elastic structure is elastically deformed into a first pattern when acceleration in the X-axis direction is generated, so that the first plate structure and the second plate structure are translated together in the first direction, and when acceleration in the Y-axis direction is generated, the second plate structure is elastically deformed. It is elastically deformed in a pattern to cause both the first plate structure and the second plate structure to translate together in a second direction, and when acceleration in the Z-axis direction occurs, it is elastically deformed in a third pattern to cause only the second plate structure to center on the X-axis. rotate with
The composite elastic structure,
a fixing unit fixed to the substrate;
a first elastic body unit having an elastic deformation structure that expands and contracts in the Y-axis direction and integrally connected to the fixing unit;
a second elastic body unit having an elastic deformation structure that expands and contracts in the X-axis direction and integrally connected to the first elastic body unit;
a connecting beam part having one part integrally connected to the second elastic body part and the other part integrally connected to the first plate structure to support the first plate structure; and
It extends along the X-axis and has one end integrally connected to the connecting beam part and the other end integrally connected to the center plate part of the second plate structure to support the second plate structure, clockwise or A single mass-based three-axis MEMS acceleration sensor comprising a torsion beam capable of elastic deformation twisted in a counterclockwise direction. delete According to claim 1,
The first elastic body part includes a beam structure extending in a zigzag or meander form along the Y-axis direction as an elastic deformation structure that expands and contracts in the Y-axis direction,
The second elastic body part comprises a ring-shaped beam structure as an elastic deformation structure that expands and contracts in the X-axis direction. According to claim 1,
The connecting beam part,
a first connecting beam part having a predetermined width and extending parallel to the Y-axis and integrally connected to the one end of the torsion beam part;
a second connecting beam part having a predetermined width and extending from the first connecting beam part and integrally connected to the first plate structure; and
A third connecting beam portion having a predetermined width and extending from the first connecting beam portion or the second connecting beam portion and integrally connected to the second elastic body portion;
The 3-axis MEMS acceleration sensor based on a single mass, characterized in that the first connecting beam part connected to the torsion beam part has a wider width than the second connecting beam part and the third connecting beam part. According to claim 1,
The center plate portion of the second plate structure and the composite elastic structure are each configured in an X-axis symmetrical structure,
The extension plate part of the second plate structure is configured to have a mass that locates the center of gravity of the second plate structure in the -Y region based on the origin and locates the center of gravity of the entire mass body on the X axis. A 3-axis MEMS acceleration sensor based on a single mass. According to claim 5,
The center plate portion of the second plate structure has a structure that is symmetrical to the X-axis and symmetrical to the Y-axis,
The extension plate portions of the first plate structure and the second plate structure are each configured in a Y-axis symmetrical structure,
The composite elastic structure includes: a first composite elastic structure positioned between the first side plate portion of the first plate structure and the center plate portion of the second plate structure; and a second composite elastic structure positioned between the second side plate portion of the first plate structure and the center plate portion of the second plate structure and having a structure symmetrical to the first composite elastic structure with respect to the Y-axis. A 3-axis MEMS acceleration sensor based on a single mass.

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