CN109682364B - Piezoelectric MEMS Decoupling Structure and MEMS Gyroscope - Google Patents

Abstract

The invention discloses a piezoelectric MEMS decoupling structure and an MEMS gyroscope, wherein the piezoelectric MEMS decoupling structure comprises: a T type beam structure, including crossbeam and the longeron of integration, this T type beam structure includes from bottom to top in proper order: a substrate, a lower electrode layer and a piezoelectric material layer; the second upper electrode is used as a detection electrode, is T-shaped, is positioned on the T-shaped beam structure, and is symmetrical about the central line of the longitudinal beam; and the first upper electrode and the third upper electrode are used as driving electrodes, are positioned on the longitudinal beam, are symmetrically distributed on two sides of the central line of the longitudinal beam, and are mutually independent from the part of the second upper electrode positioned on the longitudinal beam. The decoupling structure is provided with the T-shaped beam structure comprising the integrated cross beam and the integrated longitudinal beam in the whole shape, and the T-shaped detection electrodes which are symmetrical about the central line of the longitudinal beam and the two driving electrodes which are symmetrically distributed on the longitudinal beam are arranged on the T-shaped beam structure, so that complete decoupling is realized, and the detection precision of the gyroscope can be effectively improved.

Description

Piezoelectric MEMS Decoupling Structure and MEMS Gyroscope

technical field

The present disclosure belongs to the technical field of microelectronics, and relates to a piezoelectric MEMS decoupling structure and a MEMS gyroscope.

Background technique

Micro-electromechanical systems (MEMS, Micro-electro Mechanical Systems) devices are widely used in the field of consumer electronics due to their advantages of small size, low power consumption, low cost, and easy integration. MEMS gyroscope is the core device in inertial navigation, which can detect the angular velocity of rotating body according to the principle of Coriolis effect. According to the basic principle of MEMS gyroscope, MEMS gyroscope includes two mutually orthogonal resonance modes, namely: driving mode and detection mode. Under the excitation of the drive signal, the gyroscope structure will resonate. When there is an angular velocity, due to the Coriolis effect, there will be a detection signal output on the detection electrode under the action of the Coriolis force.

However, due to the coupling effect on the structure, when the gyroscope works in the driving mode, without the action of the external angular velocity, the gyroscope structure will also have a displacement change in the detection direction, and there will still be signal output on the detection electrode. The phenomenon is the orthogonal coupling effect of the MEMS gyroscope. The orthogonal coupling phenomenon of the gyroscope will seriously affect the detection accuracy and other characteristics of the gyroscope, so it is necessary to suppress the orthogonal coupling in the structural design. Common methods for suppressing orthogonal coupling include: electrostatic tuning, single-degree-of-freedom design of driving modes, and single-degree-of-freedom design of detection modes. However, since the gyroscope based on the Coriolis effect itself relies on coupling to realize the angular velocity detection, it is difficult to achieve complete decoupling.

SUMMARY OF THE INVENTION

(1) Technical problems to be solved

The present disclosure provides a piezoelectric MEMS decoupling structure and a MEMS gyroscope to at least partially solve the above technical problems.

(2) Technical solutions

According to an aspect of the present disclosure, a piezoelectric MEMS decoupling structure is provided, comprising: a T-beam structure 1 including an integrated cross beam 11 and a longitudinal beam 12 , the T-beam structure 1 sequentially includes from bottom to top : the substrate 101, the lower electrode layer 102 and the piezoelectric material layer 103; the second upper electrode 142, serving as a detection electrode, is T-shaped, is located on the T-shaped beam structure 1, and is symmetrical about the longitudinal beam centerline 120; and the first The upper electrode 141 and the third upper electrode 143, as driving electrodes, are located on the longitudinal beam 12, symmetrically distributed on both sides of the longitudinal beam centerline 120, and are independent from the part of the second upper electrode 142 located on the longitudinal beam 12.

In some embodiments of the present disclosure, the longitudinal beam 12 acts as a driving beam, and the cross beam 11 acts as a detection beam.

In some embodiments of the present disclosure, in the driving mode, the first upper electrode 141 and the third upper electrode 143 are connected to a pair of differential driving signals to drive the T-beam structure 1 to vibrate in-plane.

In some embodiments of the present disclosure, the first upper electrode 141 and the third upper electrode 143 have the same shape and size.

In some embodiments of the present disclosure, the portion of the second upper electrode 142 on the beam is elongated, meandering, or a combination thereof.

In some embodiments of the present disclosure, the material of the substrate 101 includes one or a combination of the following materials: silicon, silicon dioxide, and SOI.

In some embodiments of the present disclosure, the material of the piezoelectric material layer 103 includes one or a combination of the following materials: piezoelectric single crystal, piezoelectric polycrystalline thin film, polycrystalline piezoelectric ceramic, polymer piezoelectric material, and polymer Matter-piezoceramic composites.

In some embodiments of the present disclosure, the piezoelectric MEMS decoupling structure further includes: an anchor point 15 located at the end point of the stringer 12 .

According to another aspect of the present disclosure, there is provided a MEMS gyroscope including the piezoelectric MEMS decoupling structure mentioned in any one of the present disclosure.

In some embodiments of the present disclosure, the MEMS gyroscope further includes: a mass block 2, wherein the mass block 2 includes an accommodating space, and the accommodating space is used for placing the beam 11 and the vertical beam of the piezoelectric MEMS decoupling structure. Beam 12.

(3) Beneficial effects

It can be seen from the above technical solutions that the piezoelectric MEMS decoupling structure and the MEMS gyroscope provided by the present disclosure have the following beneficial effects:

The overall shape of the decoupling structure is set as a T-beam structure including an integrated cross beam and a longitudinal beam. The first upper electrode and the third upper electrode are symmetrically distributed on both sides of the center line of the longitudinal beam. It is a T-shaped electrode that is symmetrical about the center line of the longitudinal beam as a detection electrode; in the driving mode, based on the piezoelectric effect of the piezoelectric material, by applying a voltage to the upper and lower electrodes, the entire structure can be driven to generate in-plane detection. Resonance, the longitudinal beam is used as the driving beam, and the transverse beam is used as the detection beam. Due to the structural coupling, there will still be displacement deformation on the transverse beam of the T-beam, that is, the vibration of the driving mode will be coupled to the detection beam, causing displacement and deformation of the detection beam. Since the second upper electrode is left-right symmetrical with respect to the center line of the longitudinal beam, the deformation of the detection beam caused by the orthogonal coupling will polarize the same amount of opposite-sign charges at the second upper electrode. The second upper electrode achieves mutual neutralization. Therefore, the arrangement of the T-beam structure and the second upper electrode makes the structure as a whole show that there is no coupled signal output on the detection electrode, that is, complete decoupling is realized, which can effectively improve the detection accuracy of the gyroscope. .

Description of drawings

FIG. 1 is a schematic diagram of a piezoelectric MEMS decoupling structure according to an embodiment of the present disclosure.

FIG. 2 is a schematic structural diagram of a MEMS gyroscope with two piezoelectric MEMS decoupling structures according to an embodiment of the present disclosure.

3 is a schematic diagram of decoupling achieved by a piezoelectric MEMS decoupling structure in a driving mode according to an embodiment of the present disclosure, wherein (a) is the corresponding charge detection positions A, B, F, C, D in the detection electrodes Schematic diagram, (b) is a schematic diagram of the distribution of positive and negative charges on the detection electrode.

【Symbol Description】

1-T beam structure;

11 - beam; 12 - longitudinal beam;

101-substrate; 102-lower electrode layer;

103-piezoelectric material layer;

141-first upper electrode; 142-second upper electrode;

143 - the third upper electrode;

120- stringer center line; 15- anchor point;

2- Mass block.

Detailed ways

In order to solve the problems that the detection accuracy of the gyroscope is reduced due to the orthogonal coupling phenomenon, and the existing methods for suppressing the orthogonal coupling cannot achieve complete decoupling, the present disclosure proposes a piezoelectric MEMS decoupling structure and a MEMS gyroscope. The overall shape of the decoupling structure is set as a T-beam structure including integrated beams and longitudinal beams, and T-shaped detection electrodes symmetrical about the center line of the longitudinal beam and symmetrically distributed on the longitudinal beam are arranged on the T-shaped beam structure. Two drive electrodes are used to achieve complete decoupling, which can effectively improve the detection accuracy of the gyroscope.

In order to make the objectives, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below with reference to the specific embodiments and the accompanying drawings. In the present disclosure, "T-shaped" means that the shape includes a transverse direction and a longitudinal direction that intersect.

In a first exemplary embodiment of the present disclosure, a piezoelectric MEMS decoupling structure is provided.

FIG. 1 is a schematic diagram of a piezoelectric MEMS decoupling structure according to an embodiment of the present disclosure.

1, the piezoelectric MEMS decoupling structure of the present disclosure includes:

A T-beam structure 1 includes an integrated cross beam 11 and a longitudinal beam 12. The T-beam structure 1 sequentially includes from bottom to top: a substrate 101, a lower electrode layer 102 and a piezoelectric material layer 103;

The second upper electrode 142, serving as a detection electrode, is T-shaped, is located on the T-shaped beam structure 1, and is symmetrical about the centerline 120 of the longitudinal beam; and

The first upper electrode 141 and the third upper electrode 143, as driving electrodes, are located on the longitudinal beam 12, symmetrically distributed on both sides of the longitudinal beam centerline 120, and are independent of the part of the second upper electrode 142 on the longitudinal beam 12.

In this embodiment, the piezoelectric MEMS decoupling structure further includes: an anchor point 15 located at the end point of the longitudinal beam 12 for fixing the piezoelectric MEMS decoupling structure.

In this embodiment, the shapes of the substrate 101 , the lower electrode layer 102 and the piezoelectric material layer 103 are all T-shaped, and together form a T-shaped beam structure 1 , and the T-shaped beam structure 1 and the T-shaped beam structure 1 are located on top of the T-shaped beam structure 1 . The three independent upper electrodes - the first upper electrode 141, the second upper electrode 142 and the third upper electrode 143 form a piezoelectric MEMS decoupling structure as a whole. In the driving mode, based on the piezoelectric effect of the piezoelectric material, the Applying a voltage to the upper and lower electrodes can drive the entire structure to generate in-plane resonance.

Each part of the piezoelectric MEMS decoupling structure of this embodiment will be described in detail below.

In this embodiment, the material of the substrate 101 includes one or more of the following materials: silicon, silicon dioxide, and SOI (silicon-on-insulator, also known as silicon-on-insulator, which includes a layer between the top layer silicon and the insulating substrate silicon. buried oxide layer).

In this embodiment, the material of the piezoelectric material layer 103 includes one or more of the following materials: piezoelectric single crystal, piezoelectric polycrystalline film, polycrystalline piezoelectric ceramic, polymer piezoelectric material, and polymer-piezoelectric Ceramic composite materials, such as: aluminum nitride, quartz, piezoelectric ceramics, etc.

In this embodiment, the first upper electrode 141 and the third upper electrode 143, as driving electrodes, are located on the longitudinal beam 12 and are symmetrically distributed on both sides of the longitudinal beam center line 120 . In the driving mode, when the first upper electrode 141 and the third upper electrode 143 are connected to a pair of differential driving signals, the T-beam structure 1 can be driven to generate in-plane vibration.

In this embodiment, the corresponding longitudinal beams 12 are used as driving beams, and the transverse beams 11 are used as detection beams. The second upper electrode 142, serving as a detection electrode, is T-shaped, is located on the T-shaped beam structure 1, and is symmetrical with respect to the centerline 120 of the longitudinal beam.

In some embodiments of the present disclosure, the first upper electrode 141 and the third upper electrode 143 have the same shape and size.

For example, in this embodiment, the first upper electrode 141 and the third upper electrode 143 are both rectangular, and the length and width of the first upper electrode 141 and the third upper electrode 143 are the same. Of course, in other embodiments, the first upper electrode 141 and the third upper electrode 143 may also have other shapes.

In some embodiments of the present disclosure, the portion of the second upper electrode 142 on the beam is elongated, meandering, or a combination thereof.

For example, in this embodiment, the portion of the second upper electrode 142 on the beam is serpentine.

In a second exemplary embodiment of the present disclosure, there is provided a MEMS gyroscope including the piezoelectric MEMS decoupling structure described above.

FIG. 2 is a schematic structural diagram of a MEMS gyroscope with two piezoelectric MEMS decoupling structures according to an embodiment of the present disclosure.

Referring to FIG. 2 , the MEMS gyroscope of this embodiment includes: two piezoelectric MEMS decoupling structures, and a mass block 2 . The mass block 2 includes an accommodating space for placing two The beams 11 and the longitudinal beams 12 of the piezoelectric MEMS decoupling structure.

In this embodiment, as shown in FIG. 2 , the anchor points 15 of the two piezoelectric MEMS decoupling structures are located at the end points of the longitudinal beams 12 .

In order to conveniently describe the decoupling principle and characteristics of the piezoelectric MEMS decoupling structure, the following description will be given in conjunction with the complete structure of the specific gyroscope.

In this embodiment, the MEMS gyroscope in FIG. 2 includes two piezoelectric MEMS decoupling structures and a mass 2 , and the two anchor points 15 are respectively arranged at the end points of the longitudinal beams 12 of the two T-beam structures 1 . The first upper electrode 141 and the third upper electrode 143 are used as a pair of differential driving electrodes to drive the entire structure to generate in-plane vibration, which is the driving mode of the MEMS gyroscope. The MEMS gyroscope (hereinafter referred to as the gyroscope) is used for Detect the angular velocity in the z-axis direction (ie, perpendicular to the gyroscope plane). When the angular velocity of the z-axis acts on the gyroscope, a Coriolis force will be generated. Under the action of the Coriolis force, the structure of the gyroscope will vibrate in the direction of the x-axis. This vibration mode is the detection mode. , the signal of the detection mode can be detected by the second upper electrode 142 . The above is the basic principle of the working of the gyroscope.

Orthogonal coupling refers to the magnitude of the signal coupled to the detection structure by the driving mode of the gyroscope when there is no external angular velocity. In the MEMS gyroscope including the piezoelectric MEMS decoupling structure shown in the present disclosure, the sensitive component is a T-beam structure 1 , the longitudinal beam 12 of the T-beam structure 1 is used as a driving beam, and the cross beam 11 is used as a detection beam. When the gyroscope works in the driving mode, due to the structural coupling, there will still be displacement deformation on the beam 11 of the T-beam structure 1, that is, the vibration of the driving mode will be coupled to the detection beam, causing displacement and deformation of the detection beam. However, the second upper electrode 142 in the present disclosure is symmetrical about the center line 120 of the longitudinal beam, and the deformation of the detection beam caused by the orthogonal coupling will polarize the second upper electrode 142 with equal charges of opposite signs. The same amount of opposite-sign charges will neutralize each other on the second upper electrode 142, so the arrangement of the T-beam structure and the second upper electrode makes the structure as a whole appear as the detection electrode - the second upper electrode 142 has no coupled signal output, That is, complete decoupling is achieved.

3 is a schematic diagram of a piezoelectric MEMS decoupling structure in a driving mode according to an embodiment of the present disclosure to achieve decoupling, wherein (a) is the positions A, B, F, C, and D of the detection electrodes corresponding to the detection charges Schematic diagram, (b) is a schematic diagram of the distribution of positive and negative charges on the detection electrode.

In an example, as shown in FIG. 3( a ), in the driving mode, the portion of the detection electrode (the second upper electrode 142 ) located on the beam 11 is provided with several symmetrically distributed charge detection positions A, B, F (located in the center), C (symmetrical to A), and D (symmetrical to B), and their charge distributions correspond to those shown in (b) in FIG. Left and right symmetry, corresponding to the points A and B on the left side of the center point F, showing different amounts of positive charge, corresponding to the symmetrical distribution of points A and B, the positions C (symmetric to A) and D (symmetric to B) appear respectively with A and B. The negative charges of the same amount at point B and point B, in this way, the same amount of opposite-sign charges will neutralize each other on the detection electrode.

To sum up, the present disclosure provides a piezoelectric MEMS decoupling structure and a MEMS gyroscope. By setting the overall shape of the decoupling structure as a T-beam structure including integrated beams and longitudinal beams, and at the T The beam structure is provided with a T-shaped detection electrode that is symmetrical about the centerline of the longitudinal beam and two drive electrodes that are symmetrically distributed on the longitudinal beam. The first upper electrode and the third upper electrode are symmetrically distributed on both sides of the longitudinal beam centerline. Electrodes, the second upper electrode is a T-shaped electrode symmetrical about the center line of the longitudinal beam, which is used as a detection electrode; in the driving mode, based on the piezoelectric effect of the piezoelectric material, by applying a voltage to the upper and lower electrodes, it can be driven. In-plane resonance occurs in the whole structure, the longitudinal beam is used as the driving beam, and the transverse beam is used as the detection beam. Due to structural coupling, there will still be displacement deformation on the transverse beam of the T-beam, that is, the vibration of the driving mode will be coupled to the detection beam, causing The detection beam is displaced and deformed. Since the second upper electrode is left-right symmetrical with respect to the center line of the longitudinal beam, the deformation of the detection beam caused by the orthogonal coupling will polarize the same amount of opposite-sign charges at the second upper electrode. These etc. The amount of opposite-signal charges are mutually neutralized on the second upper electrode, so the arrangement of the T-beam structure and the second upper electrode makes the structure as a whole show that there is no coupled signal output on the detection electrode, that is, complete decoupling is realized, which can effectively Improve the detection accuracy of the gyroscope.

It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. Also, in the specification and claims, when an element is described as being "connected" to another element, the element can be "directly connected" to the other element or "electrically connected" to the other element through a third element . Moreover, the shapes and sizes of the components in the figures do not reflect the actual size and proportion, but merely illustrate the contents of the embodiments of the present disclosure. Furthermore, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Furthermore, the word "comprising" or "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The ordinal numbers such as "first", "second", "third", etc. used in the description and the claims are used to modify the corresponding elements, which themselves do not mean that the elements have any ordinal numbers, nor do they Representing the order of a certain element and another element, or the order in the manufacturing method, the use of these ordinal numbers is only used to clearly distinguish an element with a certain name from another element with the same name.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above-mentioned specific embodiments are only specific embodiments of the present disclosure, and are not intended to limit the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure should be included within the protection scope of the present disclosure.

Claims (10)

1. a piezoelectric MEMS decoupling structure, is characterized in that, comprises: A T-beam structure (1), comprising an integrated cross beam (11) and a longitudinal beam (12), the T-beam structure (1) sequentially includes from bottom to top: a substrate (101), a lower electrode layer (102) ) and a piezoelectric material layer (103); The second upper electrode (142), serving as a detection electrode, is T-shaped, is located on the T-shaped beam structure (1), and is symmetrical about the centerline (120) of the longitudinal beam; and The first upper electrode (141) and the third upper electrode (143), as driving electrodes, are located on the longitudinal beam (12), symmetrically distributed on both sides of the longitudinal beam center line (120), and are connected with the second upper electrode (120). The parts of the electrodes (142) located on the longitudinal beams (12) are independent of each other. 2. The piezoelectric MEMS decoupling structure according to claim 1, wherein the longitudinal beam (12) is used as a driving beam, and the transverse beam (11) is used as a detection beam. 3. The piezoelectric MEMS decoupling structure according to claim 1, wherein, in a driving mode, the first upper electrode (141) and the third upper electrode (143) are connected to a pair of differential driving signals to The T-beam structure (1) is driven to generate in-plane vibration. 4. The piezoelectric MEMS decoupling structure according to claim 1, wherein the first upper electrode (141) and the third upper electrode (143) have the same shape and size. 5. The piezoelectric MEMS decoupling structure according to claim 1, wherein a portion of the second upper electrode (142) on the beam is elongated, meandering, or a combination thereof. 6. The piezoelectric MEMS decoupling structure according to claim 1, wherein the material of the substrate (101) comprises one or a combination of the following materials: silicon, silicon dioxide, or SOI. 7. The piezoelectric MEMS decoupling structure according to claim 1, wherein the material of the piezoelectric material layer (103) comprises one or a combination of the following materials: piezoelectric single crystal, piezoelectric polycrystalline thin film, polycrystalline Crystalline piezoelectric ceramics, polymeric piezoelectric materials, and polymer-piezoelectric ceramic composites. 8. The piezoelectric MEMS decoupling structure of claim 1, further comprising: Anchor points (15) are located at the end points of the stringers (12). 9 . A MEMS gyroscope, comprising the piezoelectric MEMS decoupling structure according to any one of claims 1 to 8 . 10 . 10. The MEMS gyroscope according to claim 9, further comprising: a mass block (2), wherein the mass block (2) comprises an accommodating space, and the accommodating space is used to place the piezoelectric MEMS decoupling The beams (11) and the longitudinal beams (12) of the structure.

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