High-performance Lamb wave acoustic device structure

Abstract

The invention discloses a high-performance Lamb wave acoustic device structure, which comprises an electrode finger strip structure layer, a piezoelectric film layer, a functional film layer and a supporting substrate layer, and is characterized in that the electrode finger strip structure layer comprises a plurality of electrode finger strip assemblies arranged along the axial direction, and the electrode finger strip assemblies are positioned on the surface of the piezoelectric film layer; and a part of the piezoelectric film layer is embedded in the piezoelectric film layer. According to the Lamb wave acoustic device, a high-sound-velocity and large-electromechanical-coupling-coefficient sound wave mode can be excited on the premise that the relative bandwidth and low loss are guaranteed, the high frequency band and the large bandwidth of the Lamb wave acoustic device are achieved, and the requirements of high-speed mobile communication for the high frequency band and the large bandwidth are met.

Description

Technical Field

[0001] The invention relates to the technical field of high-performance Lamb wave acoustic device structures, and in particular to a high-performance Lamb wave acoustic device structure. Background Art

[0002] As the foundation and key of mobile communications, the RF front end is the core component of radar, satellite communication electronics and mobile terminal products. RF front-end filters are used to filter out various parasitic clutter, noise and other interference signals, mainly including device units such as filters / duplexers, power amplifiers and tags. Due to the characteristics of small size, good consistency, high reliability, low loss and good filtering performance, surface acoustic wave (SAW) filters have become the most mainstream RF front-end filters for radar, satellite communication electronics and mobile terminals. With the increasing demand for high-frequency band and large-bandwidth Lamb wave acoustic devices in high-speed mobile communications in the 5G era, it is also very important to stimulate high-speed sound and large electromechanical coupling coefficient acoustic wave modes to achieve high-frequency band and large-bandwidth Lamb wave acoustic devices.

[0003] Traditional Lamb wave acoustic devices generally have a sound velocity of around 3800m / s and a relative bandwidth of around 4%, which limits their application in high frequency bands and large bandwidths. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: how to provide a high-speed acoustic wave mode with a large electromechanical coupling coefficient while ensuring relative bandwidth and low loss, thereby realizing a high-performance Lamb wave acoustic device structure with a high frequency band and a large bandwidth.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A high-performance Lamb wave acoustic device structure includes an electrode finger structure layer, a piezoelectric film layer, a functional film layer and a supporting substrate layer. The electrode finger structure layer includes a plurality of electrode finger assemblies arranged along the axial direction. The electrode finger assemblies are located on the surface of the piezoelectric film layer and are partially embedded in the piezoelectric film layer.

[0006] Preferably, the electrode finger assembly comprises a first electrode finger portion located on the surface of the piezoelectric film layer and a second electrode finger portion embedded in the piezoelectric film layer, and both the first electrode finger portion and the second electrode finger portion are arranged obliquely.

[0007] Preferably, the first electrode finger portion and the second electrode finger portion are symmetrically arranged on two vertical sides of the surface of the piezoelectric film layer.

[0008] Preferably, the inclination directions of two adjacent first electrode finger portions are opposite to each other, and the inclination directions of two adjacent second electrode finger portions are opposite to each other.

[0009] Preferably, the inclination angles of two adjacent first electrode finger strip portions are equal, and the inclination angles of two adjacent second electrode finger strip portions are equal.

[0010] Preferably, the inclination directions of two adjacent first electrode finger strip portions are the same, and the inclination directions of two adjacent second electrode finger strip portions are the same.

[0011] Preferably, the inclination angles of two adjacent first electrode finger strip portions are equal, and the inclination angles of two adjacent second electrode finger strip portions are equal.

[0012] Preferably, the angle between the first electrode finger portion and the axial direction is a first angle, the first angle ranges from 0° to 180°, and the angle between the second electrode finger portion and the axial direction is a second angle, the second angle ranges from 0° to 180°.

[0013] Preferably, the piezoelectric film layer is a single-layer or multi-layer structure, and the functional film layer is a single-layer or multi-layer structure.

[0014] Preferably, the supporting substrate layer includes two supporting substrates arranged along the axial direction, and the two supporting substrates are respectively arranged on both sides of the axial direction of the functional film layer, and there is a gap between the two supporting substrates, so that the corresponding position of the functional film layer is designed to be suspended.

[0015] Compared with the prior art, the present invention has the following advantages: 1. The present invention adopts a finger-strip inclined structure. Compared with the traditional finger-strip, the thickness of the finger-strip in different areas is different, resulting in different propagation speeds of sound waves. This difference in sound speed causes sound wave reflection, which can constrain the main mode in the IDT area, reduce the leakage of sound waves, and stimulate a high sound speed and large electromechanical coupling coefficient sound wave mode under the premise of ensuring relative bandwidth and low loss, thereby realizing the high frequency band of more than 3G and a large bandwidth of more than 20% of the Lamb wave acoustic device, meeting the requirements of high frequency band and large bandwidth for high-speed mobile communication.

[0016] 2. The present invention can suppress the parasitic of various order noise modes by optimizing the piezoelectric film layer material and its tangent, the number and thickness of piezoelectric layers, the electrode finger layer structure material and size, the electrode finger layer structure shape and offset angle, and the supporting substrate layer structure, while being conducive to achieving the high frequency, large bandwidth, low temperature drift, high rectangularity and other performances of Lamb wave acoustic devices. It meets the requirements of high-performance surface acoustic wave filters for terminals such as high-speed mobile communications and national defense and military industries, and the preparation process used in the structure is easy to implement and easy to promote on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of a high-performance Lamb wave acoustic device in Embodiment 1 of the present invention; Figure 2 It is a structural schematic diagram of a high-performance Lamb wave acoustic device structure in Embodiment 2 of the present invention; Figure 3 It is a structural schematic diagram of a high-performance Lamb wave acoustic device structure in Embodiment 3 of the present invention; Figure 4 It is a structural schematic diagram of the high-performance Lamb wave acoustic device structure in Example 4 of the present invention.

[0018] Explanation of reference numerals: first electrode finger section 1 , second electrode finger section 2 , piezoelectric film layer 3 , functional film layer 4 , supporting substrate layer 5 . DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meaning understood by people with general skills in the field to which the present invention belongs.

[0020] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "a", "an" or "the" and other similar words do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" cover the features, wholes, steps, operations, elements and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] Embodiment 1: As attached Figure 1As shown, a high-performance Lamb wave acoustic device structure includes an electrode finger structure layer, a piezoelectric film layer 3, a functional film layer 4 and a supporting substrate layer 5. The electrode finger structure layer includes a plurality of electrode finger assemblies arranged along the axial direction. The electrode finger assemblies are located on the surface of the piezoelectric film layer 3 and are partially embedded in the piezoelectric film layer 3.

[0022] In this embodiment, the electrode finger assembly includes a first electrode finger portion 1 located on the surface of the piezoelectric film layer 3 and a second electrode finger portion 2 embedded in the piezoelectric film layer 3, and both the first electrode finger portion 1 and the second electrode finger portion 2 are arranged obliquely.

[0023] In this embodiment, the first electrode finger portion 1 and the second electrode finger portion 2 are symmetrically arranged on two vertical sides of the surface of the piezoelectric film layer 3 .

[0024] In this embodiment, the inclination directions of two adjacent first electrode finger strip portions 1 are opposite. Figure 1 As shown, the angle between the leftmost first electrode finger portion 1 and the right side of the axial direction is α, while the angle between the adjacent first electrode finger portion 1 and the left side of the axial direction is α, and the inclination directions of the two adjacent second electrode finger portions 2 are opposite, as shown in the attached figure. Figure 1 As shown, the angle between the leftmost second electrode finger portion 2 and the left side in the axial direction is β, while the angle between the adjacent second electrode finger portion 2 and the right side in the axial direction is β.

[0025] In this embodiment, the inclination angles of two adjacent first electrode finger strip portions 1 are equal. Figure 1 The angles of inclination of two adjacent second electrode finger strips 2 are equal. Figure 1 All shown are β.

[0026] In this embodiment, the angle between the first electrode finger portion 1 and the axial direction is a first angle ranging from 0° to 180°, and the angle between the second electrode finger portion 2 and the axial direction is a second angle ranging from 0° to 180°.

[0027] In this embodiment, the piezoelectric film layer 3 is a single layer, and the functional film layer 4 is a single layer structure.

[0028] In this embodiment, the supporting substrate layer 5 includes two supporting substrates arranged along the axial direction, and the two supporting substrates are respectively arranged on both sides of the axial direction of the functional film layer 4, and there is a gap between the two supporting substrates so that the corresponding position of the functional film layer 4 is suspended.

[0029] In this embodiment, the first electrode finger portion 1 and the second electrode finger portion 2 are both interdigitated electrodes, and the interdigitated electrodes are made of at least one of the following materials: aluminum Al, copper Cu, gold Au, platinum Pt, titanium Ti, chromium Cr and copper-aluminum alloy.

[0030] In this embodiment, the axial width of the piezoelectric film layer 3 is greater than or equal to the axial width of the electrode finger structure layer at the corresponding position.

[0031] In this embodiment, the size of the supporting substrate layer 5 along the axial direction is adapted to the size of the functional film layer 4 along the axial direction.

[0032] In this embodiment, the piezoelectric film layer 3 is made of at least one of the following materials: lithium niobate LiNbO3, lithium tantalate LiTaO3, quartz, lithium tetraborate, lanthanum gallium silicate, and lanthanum gallium niobate.

[0033] In this embodiment, the functional thin film layer 4 is made of at least one of the following materials: lithium niobate LiNbO3, lithium tantalate LiTaO3, quartz, lithium tetraborate, lanthanum gallium silicate, lanthanum gallium niobate, silicon Si, sapphire Sapphire, silicon carbide SiC, diamond Diamond, spinel.

[0034] In this embodiment, the support substrate layer 5 is made of at least one of the following materials: silicon Si, sapphire Sapphire, silicon carbide SiC, diamond Diamond, spinel.

[0035] Embodiment 2 The difference from the first embodiment is that in this embodiment, as shown in the attached Figure 2 As shown, the piezoelectric film layer 3 and the functional film layer 4 can also be configured as a multi-layer structure.

[0036] Embodiment 3 The difference from the first embodiment is that in this embodiment, as shown in the attached Figure 3 As shown, in this embodiment, the inclination directions of two adjacent first electrode finger strips 1 are the same. Figure 3 As shown in the figure, the angle between the leftmost first electrode finger portion 1 and the right side of the axial direction is θ, and the angle between the adjacent first electrode finger portion 1 and the right side of the axial direction is also θ, and the inclination directions of the two adjacent second electrode finger portions 2 are also the same, as shown in the figure. Figure 3 As shown, the angle between the leftmost second electrode finger portion 2 and the left side in the axial direction is γ, and the angle between the second electrode finger portion 2 adjacent thereto and the left side in the axial direction is also γ.

[0037] In this embodiment, the inclination angles of two adjacent first electrode finger strip portions 1 are equal. Figure 3 The angles of inclination of two adjacent second electrode finger strips 2 are equal. Figure 3 All shown are γ.

[0038] Embodiment 4 The difference from the third embodiment is that in this embodiment, as shown in the attached Figure 4 As shown, the piezoelectric film layer 3 and the functional film layer 4 can also be configured as a multi-layer structure.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A high-performance Lamb wave acoustic device structure, comprising an electrode finger structure layer, a piezoelectric film layer, a functional film layer and a supporting substrate layer, characterized in that: The electrode finger structure layer includes a plurality of electrode finger assemblies arranged along the axial direction. The electrode finger assemblies are located on the surface of the piezoelectric film layer and are partially embedded in the piezoelectric film layer.

2. The high performance Lamb wave acoustic device structure according to claim 1, characterized in that: The electrode finger assembly includes a first electrode finger portion located on the surface of the piezoelectric film layer and a second electrode finger portion embedded in the piezoelectric film layer, and the first electrode finger portion and the second electrode finger portion are both inclined.

3. The high performance Lamb wave acoustic device structure according to claim 2, characterized in that: The first electrode finger portion and the second electrode finger portion are symmetrically arranged on two vertical sides of the surface of the piezoelectric film layer.

4. The high performance Lamb wave acoustic device structure according to claim 2, characterized in that: The inclination directions of two adjacent first electrode finger strips are opposite to each other, and the inclination directions of two adjacent second electrode finger strips are opposite to each other.

5. The high performance Lamb wave acoustic device structure according to claim 4, characterized in that: The inclination angles of two adjacent first electrode finger strips are equal, and the inclination angles of two adjacent second electrode finger strips are equal.

6. The high performance Lamb wave acoustic device structure according to claim 2, characterized in that: The inclination directions of two adjacent first electrode finger strips are the same, and the inclination directions of two adjacent second electrode finger strips are the same.

7. The high performance Lamb wave acoustic device structure according to claim 6, characterized in that: The inclination angles of two adjacent first electrode finger strips are equal, and the inclination angles of two adjacent second electrode finger strips are equal.

8. The high performance Lamb wave acoustic device structure according to claim 2, characterized in that: The angle between the first electrode finger portion and the axial direction is a first angle, which ranges from 0° to 180°. The angle between the second electrode finger portion and the axial direction is a second angle, which ranges from 0° to 180°.

9. The high performance Lamb wave acoustic device structure according to claim 1, characterized in that: The piezoelectric film layer is a single-layer or multi-layer structure, and the functional film layer is a single-layer or multi-layer structure.

10. The high performance Lamb wave acoustic device structure according to claim 1, characterized in that: The supporting substrate layer includes two supporting substrates arranged along the axial direction, and the two supporting substrates are respectively arranged on both sides of the functional film layer in the axial direction, and there is a gap between the two supporting substrates, so that the corresponding position of the functional film layer is designed to be suspended.

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