CN217502402U

CN217502402U - Spring design structure for reducing error influence of MEMS (micro-electromechanical system) resonant device

Info

Publication number: CN217502402U
Application number: CN202221023865.6U
Authority: CN
Inventors: 黄向向; 杨敏; 亚历桑德罗·罗基; 关健; 张晓磊
Original assignee: Hanking Electronics Liaoning Co ltd
Current assignee: Hanking Electronics Liaoning Co ltd
Priority date: 2022-04-29
Filing date: 2022-04-29
Publication date: 2022-09-27
Anticipated expiration: 2032-04-29

Abstract

Reduce spring design structure of MEMS resonance device error influence, its characterized in that: the spring design structure for reducing the error influence of the MEMS resonance device comprises end points, a rigid body, a rigid connection module, a flexible beam and a fixed point; wherein: the upper end of the rigid body is an end point structure, a rigid connection module is arranged between the flexible beams parallel to the displacement direction, a fixed point is arranged below the rigid body, and a fixed point is arranged below the rigid body. The rigid body is a split structural part with an upper part and a lower part. The utility model has the advantages that: all of the aforementioned limitations are overcome by solving the problem directly in MEMS design, resulting in a device that is insensitive to etch errors. A plurality of compliant beams deflected in an alternating manner are arranged so that they achieve a self-compensating effect against etching errors. The present invention addresses the errors directly caused by non-vertical etched walls in the mechanical field without the need to implement additional and expensive electronics in the MEMS mating ASIC.

Description

Spring design structure for reducing error influence of MEMS (micro-electromechanical system) resonant device

Technical Field

The utility model relates to a microfabrication field, in particular to reduce spring design structure of MEMS resonance device error influence.

Background

MEMS structures are typically realized by cutting trenches from the surface of a structural layer, typically made of silicon or oxide, following a defined 2D geometry. Thus, the resulting device is characterized by a uniform thickness equal to the thickness of the build layer, and a typical fabrication process for cutting the trenches is deep reactive ion etching.

In the ideal case, the sidewalls of the trench are perfectly orthogonal to the structure surface: this property allows perfect separation between motion occurring in a plane parallel to the surface of the structure and motion occurring in a direction orthogonal to the surface. However, in a practical production environment, it is not possible to ensure that the desired trenches are formed throughout the MEMS wafer; thus, some devices are implemented with non-vertical trench walls, and functional motion that must occur in-plane can also be affected by unwanted out-of-plane displacement.

This phenomenon is the basis for the so-called "quadrature error" in MEMS gyroscopes, i.e. the drive motion inevitably leads to spurious displacements of the sensing mass. This displacement results in a significant degradation of the gyroscope performance. To limit yield loss while achieving acceptable device performance, designers must implement countermeasures in the companion ASIC of the MEMS.

SUMMERY OF THE UTILITY MODEL

The purpose of the invention is to solve the errors directly caused by non-vertical etched walls in the mechanical field without the need to implement extra and expensive electronics in the MEMS companion ASIC.

The utility model provides a reduce spring design structure of MEMS resonance device error influence, its characterized in that: the spring design structure for reducing the error influence of the MEMS resonant device comprises an end point 2, a rigid body 3, a rigid connection module 4, a flexible beam 5 and a fixed point 6;

wherein: the upper end of the rigid body 3 is of an end point 2 structure, a rigid connecting module 4 is arranged between flexible beams 5 parallel to the displacement direction, a fixed point 6 is arranged below the rigid body 3, and the fixed point 6 is arranged below the rigid body 3.

The rigid body 3 is a split structural member with an upper part and a lower part.

The flexible beams 5 are parallel to the displacement direction, and the flexible parts are symmetrically arranged along the length of the spring.

The flexible beam 5 has a multi-tip structure.

The flexible structure of the MEMS, which is a device insensitive to etching errors, arranges a plurality of flexible beams 5 deflected in an interactive manner, and the flexible beams 5 can realize the self-compensation effect for the etching errors.

The spring has the same function as a conventional folded beam spring, and is characterized by a flexible beam parallel to the displacement direction along the X-axis, and a rigid body coupling the flexible beam 5 to the spring tip.

Fig. 2 shows how the spring deflects when a force is applied in the displacement direction.

The flexible beam 5 deflects in an anti-symmetric manner, any plane of the flexible beam 5 is self-compensating, and even if non-vertical sidewalls of the spring are present, the spring tip does not deflect in the Z-direction when a force is applied in the X-direction.

The principle of having a flexible beam 5 parallel to the displacement direction and a rigid body 3 as a lever can be realized in various ways.

The illustrated fig. 3 shows how a conventional linear drive gyroscope can be modified to be insensitive to non-vertical trench walls.

The springs are replaced by flexible beams 5 as described in this scheme, allowing the central mass to oscillate precisely along the X-axis, even if there are etching errors, and to deflect along the Z-axis only when angular rate is applied, eliminating spurious motion along the Z-axis can give the gyroscope excellent performance.

Two tip flexible structures having a thickness in a plane XY in which one tip has a primary motion relative to the second tip, the primary motion being linear or curvilinear; where the tangency to the main movement at the remaining points of the flexible structure is called the "main displacement direction", the flexible structure is optimized to avoid manufacturing defects that cause its tip to generate unnecessary displacements orthogonal to the plane XY also when performing the main movement, the optimization being achieved by arranging the flexible structure as a combination of one or more rigid bodies and one or more flexible beams, characterized in that the direction of the flexible beams is parallel to the main displacement direction.

A general method for designing etch error insensitive flexible structures that can be applied to any conventional MEMS resonator, gyroscope, time reference, etc. is presented.

Even if non-vertical sidewalls of the spring are present, the spring tip will not deflect in the Z direction when a force is applied in the X direction.

Figure 1 shows a top view of a spring designed according to the method of the present invention. The spring has the same function as the previously shown folded beam spring, which is characterized in that now the flexible beam is parallel to the displacement direction along the X-axis, and there is also a rigid body coupling the flexible beam to the spring tip.

Fig. 2 shows how the spring deflects when a force is applied in the displacement direction. The beam deflects in an anti-symmetric manner, so any out-of-plane contribution of the beam is self-compensating, and even with the non-vertical sidewalls of the spring, the spring tip does not deflect in the Z-direction when a force is applied in the X-direction.

The principle of having a flexible beam parallel to the displacement direction and a rigid body as a lever can be implemented in many different embodiments:

figure 2 shows a spring similar to that of figure 1 in which the flexible portions are symmetrically arranged along the length of the spring.

Figure 5 shows how a conventional linear drive gyroscope can be modified to be insensitive to non-vertical trench walls.

The conventional spring is replaced by a flexible design as described in this patent, modified to allow the center mass to oscillate precisely along the X-axis, even if there is an etch error, and to deflect along the Z-axis only when angular rate is applied. Eliminating spurious motion along the Z-axis can provide superior performance to the gyroscope.

The utility model has the advantages that:

reduce spring design structure of MEMS resonance device error influence, through direct solution problem in the MEMS design, overcome all restrictions of aforementioned, can realize MEMS flexible construction's specific design to obtain the device insensitive to the etching error. The key to achieving this goal is to arrange a plurality of compliant beams that deflect in an alternating manner so that they achieve a self-compensating effect against etch errors. The present invention addresses the errors directly caused by non-vertical etched walls in the mechanical field without the need to implement additional and expensive electronics in the MEMS mating ASIC.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and embodiments:

FIG. 1 is a top view of a spring design structure for reducing the error effect of a MEMS resonator device, wherein 1 is a displacement direction;

FIG. 2 is a schematic view of how the spring deflects when a force is applied in the displacement direction;

FIG. 3 is a schematic view of the symmetrical arrangement of the flexible portions along the length of the spring;

FIG. 4 is a second schematic view of the flexible portion being symmetrically disposed along the length of the spring;

figure 5 is a schematic diagram of a linear drive mass-spring resonator.

Detailed Description

Example 1

The utility model provides a reduce spring design structure of MEMS resonance device error influence, its characterized in that: the spring design structure for reducing the error influence of the MEMS resonance device comprises an end point 2, a rigid body 3, a rigid connection module 4, a flexible beam 5 and a fixed point 6;

The spring is replaced by a flexible beam 5 as described in this solution, allowing the central mass to oscillate precisely along the X-axis, even in the presence of etching errors, and to deflect along the Z-axis only when angular rate is applied, eliminating spurious motion along the Z-axis allowing superior performance of the gyroscope.

Two tip flexible structures of a given thickness designed in a plane XY in which one tip has a primary motion relative to the second tip, the primary motion being either linear or curvilinear, wherein the primary motion at the remaining points of the flexible structure is tangential, called the "primary displacement direction", the flexible structure being optimized to avoid manufacturing defects causing its tip to also produce an unnecessary displacement orthogonal to the plane XY when performing the primary motion, the optimization being achieved by arranging the flexible structure as a combination of one or more rigid bodies and one or more flexible beams, characterized by the direction of the flexible beams being parallel to the primary displacement direction.

Example 2

The flexible beam 5 has a multi-tip structure. The remainder is made up of any combination of the flexible structures described in example 1.

The utility model is not the best known technology.

The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose of the embodiments is to enable people skilled in the art to understand the contents of the present invention and to implement the present invention, which cannot limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.

Claims

1. Reduce spring design structure of MEMS resonance device error influence, its characterized in that: the spring design structure for reducing the error influence of the MEMS resonant device comprises an end point (2), a rigid body (3), a rigid connection module (4), a flexible beam (5) and a fixed point (6);

wherein: the upper end of the rigid body (3) is of an end point (2) structure, a rigid connecting module (4) and a fixed point (6) are arranged between the flexible beams (5) parallel to the displacement direction, and the fixed point (6) is arranged below the rigid body (3).

2. The spring design structure for reducing the error impact of the MEMS resonator device of claim 1, wherein: the rigid body (3) is a split structural member with an upper part and a lower part.

3. The spring design structure for reducing the error impact of the MEMS resonator device of claim 1, wherein: and the flexible beams (5) are parallel to the displacement direction, and the flexible parts are symmetrically arranged along the length of the spring.

4. The spring design structure for reducing the error impact of the MEMS resonator device of claim 1, wherein: the flexible beam (5) has a multi-tip structure.