Structure of surface acoustic wave device on basis of flexible substrate and manufacturing method of surface acoustic wave device

Abstract

The invention relates to a surface acoustic wave (Surface Acoustic Wave, SAW) device on the basis of a flexible substrate and a preparation method thereof. The SAW device comprises a substrate, a bottom electrode layer, a piezoelectric layer and a top electrode layer. A working area is formed by the bottom electrode layer, the piezoelectric layer and the top electrode layer. The SAW device is characterized in that the flexible substrate is arranged below the bottom electrode layer; and the flexible substrate is provided with an opening. The SAW device and the preparation method thereof have the characteristics that 1, due to the adoption of the flexible substrate, the obtained device is light, can be mounted on a curved surface, can be continuously produced in a roll-to-roll mode, and has simple manufacturing process and low cost; and 2, the flexible substrate is subjected to reverse side body deep etching to form the opening so that sound waves are spread in the piezoelectric layer in a plate wave mode, a high resonant frequency can be obtained, and meanwhile, the energy of the sound waves is limited in the working area so that a high device Q value can be obtained. Moreover, when a plate wave mode resonator is applied to a liquid sensor, the Q value cannot be reduced due to the radiation of the energy into the liquid.

Description

technical field [0001] The invention relates to the technical field of surface acoustic wave devices, in particular to a structure of a surface acoustic wave device based on a flexible substrate and a manufacturing method thereof. Background technique [0002] Surface Acoustic Wave (SAW) is an elastic wave that propagates along the surface or interface of an elastic solid, and a SAW device is a device that uses SAW to complete various complex signal processing. With the rapid development of semiconductor planar technology, material science, micromachining technology (MEMS), microelectronics technology and computer technology, SAW devices are being used for their miniaturization, multi-function, high frequency, high reliability and digital output. It is widely used in various military and civilian electronic systems such as mobile communication, aerospace, radar, electronic countermeasures, remote control telemetry, radio and television, sensors, etc. [0003] Traditional su...

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Problems solved by technology

In these published patents, all the substrates are rigid materials with high mass and cannot be bent, so the roll-to-roll continuous production cannot be performed during the preparation process, and the prepared devices cannot be installed on curved surfaces. , which greatly limits the production and application of surface acoustic wave devices

[0004]Traditional piezoelectric thin film SAW devices use piezoelectric thin films to excite Rayleigh waves. Since the sound velocity of Rayleigh waves is lower than that of symmetrical plate waves, the The resonant frequency of the prepared device is relatively low, and it is difficult to adapt to high-frequency wireless communication applications in integrated circuits; in addition, when the sensor based on the Rayleigh wave mode is applied to a liquid sensor, due to the longitudinal movement of the particles, energy will radiate into the liquid , leading to lower Q

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