A MEMS structure

Abstract

The present application discloses a MEMS structure, comprising: a substrate having a cavity; a piezoelectric composite vibration layer formed on the substrate and covering the cavity, wherein the piezoelectric composite vibration layer has a first region located above the substrate and a second region located above the cavity, and a groove in the first region extends from the upper surface of the piezoelectric composite vibration layer to the lower surface of the piezoelectric composite vibration layer. The present application improves the sensitivity of the MEMS structure by setting the groove to surround the second region.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a MEMS (abbreviation for MicroelectroMechanical Systems) structure. Background Art

[0002] MEMS microphones mainly include capacitive and piezoelectric types. MEMS piezoelectric microphones are microphones made using micro-electromechanical system technology and piezoelectric film technology. Due to the use of semiconductor planar technology and bulk silicon processing technology, they are small in size, small in volume, and have good consistency. At the same time, compared with capacitive microphones, they also have the advantages of not requiring bias voltage, a wide operating temperature range, and being dustproof and waterproof. However, their sensitivity is relatively low, which restricts the development of MEMS piezoelectric microphones.

[0003] With regard to the problem of how to improve the sensitivity of the piezoelectric MEMS structure in the related technology, no effective solution has been proposed yet. Summary of the invention

[0004] In view of the problem of low sensitivity of MEMS structures in related technologies, the present application proposes a MEMS structure that can improve sensitivity.

[0005] The technical solution of this application is implemented as follows:

[0006] According to one aspect of the present application, a MEMS structure is provided, comprising:

[0007] a substrate having a cavity;

[0008] A piezoelectric composite vibration layer is formed above the substrate and covers the cavity, wherein the piezoelectric composite vibration layer has a first area located above the substrate and a second area located above the cavity, and within the first area a groove extends from the upper surface of the piezoelectric composite vibration layer to the lower surface of the piezoelectric composite vibration layer.

[0009] Wherein, from a top-down view of the MEMS structure, the groove continuously surrounds the second region in a circumferential direction, and the groove includes a plurality of circumferentially evenly arranged zigzag grooves or wavy grooves.

[0010] Wherein, from a top view of the MEMS structure, the groove includes a plurality of radial grooves evenly arranged in a circumferential direction.

[0011] Wherein, the piezoelectric composite vibration layer comprises:

[0012] a vibration support layer formed above the substrate and covering the cavity;

[0013] A first electrode layer formed above the vibration support layer;

[0014] a first piezoelectric layer formed above the first electrode layer;

[0015] A second electrode layer is formed on the first piezoelectric layer.

[0016] Wherein, the piezoelectric composite vibration layer comprises:

[0017] a third electrode layer formed on the substrate;

[0018] a second piezoelectric layer formed above the third electrode layer;

[0019] a fourth electrode layer formed on the second piezoelectric layer;

[0020] a third piezoelectric layer formed above the fourth electrode layer;

[0021] A fifth electrode layer is formed on the third piezoelectric layer.

[0022] In the MEMS structure of the above embodiment, a groove is provided to surround the second region, thereby improving the sensitivity of the MEMS structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] When read in conjunction with the accompanying drawings, various aspects of the present application can be better understood from the following detailed description. It should be emphasized that, in accordance with standard industry practice, the various components are not drawn to scale and are only used for illustrative purposes. In fact, the size of the various components can be arbitrarily increased or reduced for clear discussion.

[0025] Figure 1 shows a cross-sectional view of a MEMS structure according to some embodiments;

[0026] Figure 2 A perspective view of a MEMS structure according to some embodiments is shown, wherein: Figure 1 yes Figure 2 AA cross-sectional diagram of ;

[0027] Figure 3 A perspective view of a MEMS structure according to some embodiments is shown. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0029] See also Figure 1 and Figure 2 , shows a MEMS structure according to an embodiment of the present application, which is used for sensors such as microphones or other actuators. The MEMS structure will be described in detail below.

[0030] The MEMS structure comprises a substrate 10 having a cavity 11. The substrate 10 comprises silicon or any suitable silicon-based compound or derivative (eg, silicon wafer, SOI, polysilicon on SiO2 / Si).

[0031] The piezoelectric composite vibration layer 20 is formed on the substrate 10 and covers the cavity 11. The piezoelectric composite vibration layer 20 has a first region 31 located above the substrate 10 and a second region 32 located above the cavity 11, and a groove 33 in the first region 31 extends from the upper surface of the piezoelectric composite vibration layer 20 to the lower surface of the piezoelectric composite vibration layer 20.

[0032] See also Figure 2 In some embodiments, from a top view of the MEMS structure, the groove 33 continuously surrounds the second region 32 circumferentially, and the groove 33 includes a plurality of circumferentially uniformly arranged zigzag grooves 34 or wavy grooves. Figure 3 In some embodiments, from a top view of the MEMS structure, the groove 33 includes a plurality of radial grooves 35 evenly arranged in the circumferential direction. The groove 33 in the MEMS structure based on this structure improves the sensitivity of the MEMS structure.

[0033] The structure of the piezoelectric composite vibration layer 20 will be described in detail below.

[0034] See also Figure 1 In an embodiment where the piezoelectric composite vibration layer 20 is a single crystal, the piezoelectric composite vibration layer 20 includes a vibration support layer 21, a first electrode layer 22, a first piezoelectric layer 23, and a second electrode layer 24. The vibration support layer 21 is formed above the substrate 10 and covers the cavity 11. The first electrode layer 22 is formed above the vibration support layer 21. The first piezoelectric layer 23 is formed above the first electrode layer 22. The second electrode layer 24 is formed above the first piezoelectric layer 23. In other words, the groove 33 extends from the upper surface of the second electrode layer 24 to the lower surface of the vibration support layer 21. The first piezoelectric layer 23 can convert the applied pressure into a voltage, and the first electrode layer 22 and the second electrode layer 24 can transmit the generated voltage to other integrated circuit devices.

[0035] In an embodiment where the piezoelectric composite vibration layer 20 is a bimorph (not shown in the figure), the third electrode layer is formed above the substrate 10. The second piezoelectric layer is formed above the third electrode layer. The fourth electrode layer is formed above the second piezoelectric layer. The third piezoelectric layer is formed above the fourth electrode layer. The fifth electrode layer is formed above the third piezoelectric layer. In other words, the groove 33 extends from the upper surface of the fifth electrode layer to the lower surface of the third electrode layer.

[0036] In some embodiments, the vibration support layer 21 includes a single layer or multilayer composite film structure composed of silicon nitride (Si3N4), silicon oxide, single crystal silicon, polycrystalline silicon, or other suitable supporting materials. The first piezoelectric layer 23 includes zinc oxide, aluminum nitride, organic piezoelectric film, lead zirconate titanate (PZT), perovskite piezoelectric film, or other suitable materials. The first electrode layer 22 and the second electrode layer 24 include aluminum, gold, platinum, molybdenum, titanium, chromium, and composite films composed thereof, or other suitable materials.

[0037] In summary, in the MEMS structure with the groove 33 of the above technical solution of the present application, the groove 33 continuously surrounds the second area 32 in a circumferential direction when viewed from a top view, or the groove 33 includes a plurality of radial grooves 35 evenly arranged in the circumferential direction. Such a groove 33 is conducive to improving the sensitivity of the MEMS structure.

[0038] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A MEMS structure, characterized in that: include: a substrate having a cavity; a piezoelectric composite vibration layer, formed above the substrate and covering the cavity, wherein the piezoelectric composite vibration layer has a first region located above the substrate and a second region located above the cavity, and within the first region, a groove extends from an upper surface of the piezoelectric composite vibration layer to a lower surface of the piezoelectric composite vibration layer; Wherein, the substrate includes: silicon or silicon-based compounds.

2. The MEMS structure according to claim 1, characterized in that: From a top view of the MEMS structure, the groove continuously circumferentially surrounds the second region, and the groove includes a plurality of circumferentially uniformly arranged zigzag grooves or wavy grooves.

3. The MEMS structure according to claim 1, characterized in that: From a top view of the MEMS structure, the groove includes a plurality of radial grooves evenly arranged in a circumferential direction.

4. The MEMS structure according to claim 1, characterized in that: The piezoelectric composite vibration layer comprises: a vibration support layer formed above the substrate and covering the cavity; A first electrode layer formed above the vibration support layer; a first piezoelectric layer formed above the first electrode layer; A second electrode layer is formed on the first piezoelectric layer.

5. The MEMS structure according to claim 1, characterized in that: The piezoelectric composite vibration layer comprises: a third electrode layer formed on the substrate; a second piezoelectric layer formed above the third electrode layer; a fourth electrode layer formed on the second piezoelectric layer; a third piezoelectric layer formed above the fourth electrode layer; A fifth electrode layer is formed on the third piezoelectric layer.

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