A surface acoustic wave device based on diamond material matrix

Abstract

The present invention discloses a surface acoustic wave device based on a diamond material matrix. The device comprises a diamond material matrix, a patterned piezoelectric material and an electrode; the diamond material matrix is ​​used for the transmission of surface acoustic waves; the patterned piezoelectric material is arranged on the diamond material matrix, and the patterned piezoelectric material is used for the conversion between microwave and acoustic waves; the thickness of the patterned piezoelectric material is 1 / 2 of the wavelength of the resonant body acoustic wave; the electrode is arranged on the patterned piezoelectric material, and the electrode is used for the input and output of microwaves; the polarities of adjacent electrodes are opposite. The present invention utilizes diamond material as the main acoustic propagation medium of the device, thereby achieving very low device loss.

Description

Technical Field

[0001] The invention relates to the field of microwave devices, in particular to a surface acoustic wave microwave device based on a diamond material matrix. Background Art

[0002] Surface acoustic wave devices play a vital role in various communication devices, systems, and terminals. Their technical indicators and characteristics are the key to the performance of communication equipment. If the acoustic wave transmission loss of the material can be significantly reduced, the anti-interference ability and power consumption of the communication equipment will be greatly improved. Without changing the design of existing surface acoustic wave devices, it is crucial for modern communication equipment to achieve a significant reduction in transmission loss through the application of new materials. With the increasingly tight spectrum resources today, the demand for technologies such as miniaturization, high integration, low power consumption, and low heat generation is becoming more and more urgent.

[0003] Traditional surface acoustic wave devices are mainly composed of a substrate, a piezoelectric film, and interdigital electrodes. Among them, the interdigital electrodes are formed on the piezoelectric film through thin film deposition, photolithography, and etching using traditional integrated circuit technology. The signal is input into the interdigital electrodes on one side, and the microwave signal is converted into an acoustic wave signal through the piezoelectric material and transmitted in the piezoelectric film. Then, the acoustic wave signal is converted into a microwave signal for output through the inverse piezoelectric effect at the interdigital electrodes on the other side. Through appropriate piezoelectric film and electrode design, acoustic wave signals that meet specific frequency requirements can pass through to achieve resonance and filtering functions. Although traditional surface acoustic wave devices can also achieve filtering functions, there are the following shortcomings that need to be overcome:

[0004] 1. Conventional piezoelectric materials have large acoustic wave losses, and the sensitivity and anti-interference ability of surface acoustic wave devices made of them are significantly reduced.

[0005] 2. The use of other materials makes it incompatible with traditional integrated circuit technology and difficult to achieve large-scale mass production.

[0006] 3. The diamond film under the non-patterned piezoelectric film can only increase the response frequency of the device, but has no obvious improvement on the device loss. Summary of the invention

[0007] In order to overcome the shortcomings of the prior art, the present invention provides a surface acoustic wave device based on a diamond material matrix.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] A surface acoustic wave device based on a diamond material matrix comprises a diamond material matrix, a patterned piezoelectric material and an electrode; the diamond material matrix is ​​used for the transmission of surface acoustic waves; the patterned piezoelectric material is arranged on the diamond material matrix, and the patterned piezoelectric material is used for the conversion between microwaves and acoustic waves; the thickness of the patterned piezoelectric material is 1 / 2 of the wavelength of the acoustic wave of the resonator; the electrode is arranged on the patterned piezoelectric material, and the electrode is used for the input and output of microwaves; the polarities of adjacent electrodes are opposite.

[0010] Optionally, the diamond material matrix is ​​made of single crystal or polycrystalline high-purity diamond.

[0011] Optionally, the patterned piezoelectric material is an interdigitated structure.

[0012] Optionally, the diamond material substrate is prepared by chemical vapor deposition.

[0013] Optionally, the piezoelectric film and the electrode are prepared by PVD deposition method.

[0014] Optionally, a semiconductor process is used to prepare a patterned piezoelectric material through photolithography-ion etching-stripping-protection.

[0015] Compared with the prior art, the present invention has the following technical effects: the present invention maintains the original microwave-acoustic wave conversion and microwave signal selection characteristics of conventional surface acoustic wave devices; uses diamond material as the main sound propagation medium of the device, thereby achieving very low device loss; and the piezoelectric material and electrode forming process are compatible with large-scale integrated circuit processes. Based on the characteristics of device scalability and optimization, easy compatibility with conventional devices, and simple process, the present invention realizes that the surface acoustic wave device uses diamond material to reduce microwave loss, and can be applied to various microwave radio frequency components, equipment and systems as high-frequency, high-power, high-performance frequency selection devices. Different working modes and working frequencies can be realized through piezoelectric materials and electrode circuit design, and the working mode and working frequency can be expanded and changed according to user needs, which enhances the diversity and flexibility of the device working mode and frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention 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 invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 This is a schematic structural diagram of a surface acoustic wave device based on a diamond material matrix according to an embodiment of the present invention;

[0018] Figure 2 Schematic diagram of a circuit of a piezoelectric material and an electrode according to an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of a surface acoustic wave device based on a diamond material matrix after packaging according to an embodiment of the present invention;

[0020] Figure 4 This is a performance curve diagram of a surface acoustic wave device based on a diamond material matrix according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments 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.

[0022] The purpose of the present invention is to provide a surface acoustic wave device based on a diamond material matrix, using the diamond material as the main sound propagation medium of the device, thereby achieving very low device loss.

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, a surface acoustic wave device based on a diamond material matrix includes a diamond material matrix, a patterned piezoelectric material and an electrode. The diamond material matrix is ​​used for the transmission of surface acoustic waves. The material used for the diamond material matrix is ​​single crystal or polycrystalline high-purity diamond. The length, width and height dimensions can be customized. The typical dimensions are 3*3*0.5mm (sheet crystal) or 3*3*0.03mm (thin film, silicon as the matrix). The impurity N content is at the PPB level, and the surface roughness Ra<5nm. The diamond material matrix is ​​prepared by chemical vapor deposition. Diamond material is used to replace the single piezoelectric material in the traditional thin film surface acoustic wave resonator. Diamond material serves as the main acoustic wave transmission medium, providing the best acoustic wave propagation medium for surface acoustic wave devices.

[0025] The patterned piezoelectric material is arranged on the diamond material substrate, and the patterned piezoelectric material is a forked finger structure, and the thickness of the patterned piezoelectric material is 1 / 2 of the wavelength λ of the resonant body acoustic wave. The patterned piezoelectric material is used for the mutual conversion of microwave-acoustic waves between piezoelectric materials, and excites the body acoustic waves of the corresponding frequency propagating along the thickness direction. The body acoustic waves with opposite phases between different forked fingers excite the surface acoustic waves of the corresponding frequency on the diamond material substrate below, and realize the basic functions of the surface acoustic wave device. The patterned piezoelectric material is prepared by photolithography-ion etching-stripping-protection using semiconductor technology.

[0026] The electrodes are arranged on the patterned piezoelectric material, and the polarities of the adjacent electrodes are opposite. The piezoelectric film and the electrodes are prepared by PVD deposition method. Microwave signals with opposite phases are alternately applied or formed on the electrodes for microwave input and output.

[0027] The surface acoustic wave circuit in this embodiment is as follows Figure 2 The figure shows a typical thin film surface acoustic wave device circuit. The piezoelectric material and the electrode are formed together by photolithography and etching. The interdigital width is also 1.7 microns. The specific circuit can be defined by the customer according to the actual device mode and frequency. The input and output circuits are placed on both sides of the chip. See the packaging effect diagram. Figure 3 .

[0028] The above structure can be designed by designers themselves by adjusting the composition, thickness and shape size of the piezoelectric material to achieve the device's response to microwave spectra of different frequencies, bandwidths, etc.

[0029] The multilayer structure of the surface acoustic wave device based on diamond material matrix can be self-supporting or based on other substrate materials, that is, the above multilayer structure can be self-supporting with diamond as matrix, or the multilayer structure can be formed on other substrate materials such as silicon.

[0030] Using common microwave design, simulation software and microwave test instruments, this structural acoustic surface wave device can be simulated and tested. The performance curve is shown in Figure 4 The positive "n"-shaped curve shows the S21 (transmission coefficient) of the filter, which is the voltage ratio of microwaves transmitted from the input to the output. It is close to 0dB near the middle 1.75GHz (logarithmic mode, the ratio is 1), indicating that microwave signals can pass through completely. The S21 of microwave signals below or above the passband frequency drops significantly to -50dB and below, which is obviously suppressed, indicating that microwave signals cannot pass through.

[0031] The inverted "n" curve shows the S11 (reflection coefficient) of the filter. There are many fluctuations in the passband. The voltage ratio of the microwave reflected from the input end to the input end has a maximum value of less than -20dB in the passband, indicating that almost no signal is reflected to the input end in the passband; the S11 of the microwave signal below or above the passband frequency is 0 (logarithmic mode, the ratio is 1), indicating that all the signals are reflected back to the input end.

[0032] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: the present invention maintains the original microwave-acoustic wave conversion and microwave signal selection characteristics of conventional surface acoustic wave devices; uses diamond material as the main sound propagation medium of the device, thereby achieving very low device loss; and the piezoelectric material and electrode forming process are compatible with large-scale integrated circuit processes. Based on the characteristics of device scalability and optimization, easy compatibility with conventional devices, and simple process, the present invention realizes that the surface acoustic wave device uses diamond material to reduce microwave loss, and can be applied to various microwave radio frequency components, equipment and systems as high-frequency, high-power, high-performance frequency selection devices. Different working modes and working frequencies can be realized through piezoelectric materials and electrode circuit design, and the working mode and working frequency can be expanded and changed according to user needs, which enhances the diversity and flexibility of the device working mode and frequency.

[0033] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0034] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A surface acoustic wave device based on a diamond material matrix, characterized in that: It comprises a diamond material substrate, a patterned piezoelectric material and an electrode; the diamond material substrate is used for the transmission of surface acoustic waves; the patterned piezoelectric material is arranged on the diamond material substrate, and the patterned piezoelectric material is used for the conversion between microwaves and acoustic waves; the thickness of the patterned piezoelectric material is 1 / 2 of the wavelength of the acoustic wave of the resonator; the electrode is arranged on the patterned piezoelectric material, and the electrode is used for the input and output of microwaves; the polarities of adjacent electrodes are opposite; the patterned piezoelectric material is an interdigitated structure; the material used for the diamond material substrate is single crystal or polycrystalline high-purity diamond.

2. The surface acoustic wave device of the diamond material matrix according to claim 1, characterized in that: The diamond material substrate is prepared by chemical vapor deposition.

3. The surface acoustic wave device of the diamond material matrix according to claim 1, characterized in that: The piezoelectric films and electrodes were prepared by PVD deposition method.

4. The surface acoustic wave device of the diamond material matrix according to claim 1, characterized in that: The semiconductor process is adopted to prepare the patterned piezoelectric material through photolithography-ion etching-stripping-protection.

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