Surface acoustic wave (SAW) device having high electromechanical coupling coefficient and high centre frequency

A surface acoustic wave device, electromechanical coupling technology, applied in electrical components, impedance networks, etc., can solve the problems of poor frequency stability of center frequency and electromechanical coupling coefficient, and achieve the effect of improving comprehensive performance, improving stability and expanding application fields

Inactive Publication Date: 2017-09-15
TIANJIN UNIVERSITY OF TECHNOLOGY
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  • Description
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AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the existing "ZnO / diamond", "AlN / diamond" and "ZnO / AlN / diamond" (or "AlN / ZnO / diamond") structure SAW device central frequency and electromechanical coupling coefficient increase The problems of mutual constraints and poor frequency stability provide a method based on "(AlN / ZnO) N SAW device with high frequency and high electromechanical coupling coefficient of / diamond" structure

Method used

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  • Surface acoustic wave (SAW) device having high electromechanical coupling coefficient and high centre frequency

Examples

Experimental program
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Effect test

Embodiment 1

[0015] Such as figure 1 Shown based on "IDT / (AlN / ZnO) N A high-frequency surface acoustic wave device with a " / diamond" structure, which sequentially includes a base layer, a piezoelectric layer, and an interdigital transducer on the upper surface; the surface acoustic wave device uses a diamond film as a substrate, and uses AlN and ZnO thin films to be periodically laminated The structure of (AlN / ZnO) N As a piezoelectric layer, the period N of the laminated structure ranges from 2 to 5, and the thickness ratio R of the AlN film and the ZnO film is h ranges from 0.2 to 5, both AlN and ZnO thin films are c-axis preferentially oriented, and their c-axis is along the normal direction of the substrate, and the thickness of the periodic stacked structure of AlN and ZnO thin films is less than one wavelength.

[0016] The fabrication process of the surface acoustic wave device is as follows:

[0017] 1. A polished CVD diamond film is used as a substrate, the thickness of the sub...

Embodiment 2

[0022] The structure of the high-frequency surface acoustic wave device is the same as in Example 1, and its preparation process is as follows:

[0023] 1. A polished CVD diamond film is used as a substrate, the thickness of the substrate is 50 μm, and the surface roughness is 5 nm.

[0024] 2. Prepare AlN and ZnO piezoelectric films with c-axis preferential orientation by magnetron sputtering, the thicknesses of which are about 133nm and 266nm respectively, the thickness ratio of AlN and ZnO films is 0.5, and the number of cycles is 3. The thickness is 1.2 μm.

[0025] 3. An Al film with a thickness of 150 nm was prepared by vapor deposition, and an interdigital transducer with an interdigital width and spacing of 500 nm was prepared by photolithography. The IDT can be placed on the upper surface of the piezoelectric layer, or between the piezoelectric layer and the diamond substrate.

[0026] 4. The center frequency of the SAW device is 3.0GHz, and the electromechanical co...

Embodiment 3

[0028] The structure of the high-frequency surface acoustic wave device is the same as in Example 1, and its preparation process is as follows:

[0029] 1. A polished CVD diamond film is used as a substrate, the thickness of the substrate is 50 μm, and the surface roughness is 5 nm.

[0030] 2. The AlN and ZnO piezoelectric films with c-axis preferred orientation are prepared by magnetron sputtering, the thicknesses of which are 120nm and 120nm respectively, the thickness ratio of AlN and ZnO films is 1, and the number of cycles is 5, then the total The thickness is 1.2 μm.

[0031] 3. An Al film with a thickness of 150 nm was prepared by vapor deposition, and an interdigital transducer with an interdigital width and spacing of 500 nm was prepared by photolithography. The IDT can be placed on the upper surface of the piezoelectric layer, or between the piezoelectric layer and the diamond substrate.

[0032] 4. The center frequency of the SAW device is 3.5GHz, and the electro...

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Abstract

The invention relates to a surface acoustic wave (SAW) device having high electromechanical coupling coefficient and high centre frequency. The SAW device adopts a diamond film as the substrate, and adopts an AlN and ZnO film periodically stacked structure (AlN/ZnO)<N> as the piezoelectric layer; the period N of the stacked structure is 2-5; and the thickness ratio of R<h> of an AlN film to a ZnO film is 0.2-5. According to the SAW device disclosed by the invention, respective advantages and disadvantages of two piezoelectric materials including AlN and ZnO are considered; the cooperative effect of the two is utilized, so that the comprehensive performance of the device is improved; under the same interdigital width, compared with the ZnO and AlN double-piezoelectric-layer structure, the structure has the advantages that: the electromechanical coupling coefficient of the device can be maximally increased by two times; furthermore, the centre frequency cannot be reduced; simultaneously, the temperature stability of the device is also improved; the frequency temperature coefficient is reduced; in addition, when the SAW device is designed, more adjustable parameters of the structure exist; the performance parameter adjusting range of the device is relatively wide; and thus, the application field of the device is enlarged.

Description

technical field [0001] The present invention relates to a surface acoustic wave device, in particular to a device based on "(AlN / ZnO) N "High-frequency surface acoustic wave devices with periodic structure piezoelectric layers and diamond substrates belong to the field of thin film electronic devices. Background technique [0002] Surface acoustic wave (SAW) devices are widely used in radar, electronic warfare, sonar, wireless communication, optical fiber communication and broadcast television systems due to their advantages of miniaturization, high reliability, multi-function and good consistency. With the rapid development of mobile communication, the application frequency continues to increase, making the radio communication frequency band a limited and precious resource. The frequency band below 2.5 GHz has been fully occupied, and high-frequency SAW devices are urgently needed. [0003] The center frequency of the SAW device is determined by the electrode width of the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03H9/02H03H9/58H03H3/02
CPCH03H3/02H03H9/02543H03H9/02637H03H9/582H03H2003/023
Inventor 李翠平钱莉荣李明吉李红姬曹菲菲季来运杨保和
Owner TIANJIN UNIVERSITY OF TECHNOLOGY
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