Method of manufacturing film bulk acoustic resonator on flexible substrate

Abstract

The invention discloses a method of manufacturing a film bulk acoustic resonator on a flexible substrate. The method comprises the following steps: selecting a silicon substrate, and orderly coating a water soluble polymer film layer and a polyimide film layer on the silicon substrate; manufacturing the film bulk acoustic resonator above the polyimide film layer; manufacturing a metal post at the top face of an upper electrode of the film bulk acoustic resonator; coating a polymethyl methacrylate film layer at the at the top face of the upper electrode of the film bulk acoustic resonator; coating glue of a used flexible substrate on the silicon substrate and curing the glue; placing the whole finished structure in water to separate the polyimide film layer from the silicon substrate; using corrosive liquid to remove the metal post; placing the above structure into an acetone solution, dissolving the polymethyl methacrylate film layer, and forming an air gap; and removing the polyimide film layer below the film bulk acoustic resonator. By using the method of the invention to manufacture the film bulk acoustic resonator on the flexible substrate, the resonance performance of a device can be enhanced and the processing quality of the device can be guaranteed.

Description

technical field [0001] The invention belongs to the technical field of micro-electromechanical systems, and in particular relates to a method for manufacturing a film bulk acoustic wave resonator on a flexible substrate. Background technique [0002] Thin film bulk acoustic resonator is a new type of MEMS device developed in recent years. The basic structure of thin film bulk acoustic resonator is composed of piezoelectric film and electrodes, and its working frequency reaches several gigahertz. The working principle of the device is to use the piezoelectric effect of the piezoelectric film in the device to convert the input electrical energy into mechanical energy, and form a standing wave resonance in the piezoelectric film in the form of sound waves. Thin film bulk acoustic resonator has the advantages of lower insertion loss, larger power capacity, higher Q value, integration and miniaturization. Thus, thin-film bulk acoustic resonators exhibit enormous performance adv...

AI Technical Summary

Problems solved by technology

[0006] The main disadvantage of the above technical solution is that the manufactured thin film bulk acoustic resonator has one side directly contacting the flexible substrate

Due to the viscous damping characteristics of the flexible material itself to mechanical vibration, the bulk acoustic wave in the piezoelectric film will be severely lost in the flexible substrate, resulting in attenuation of device performance

In addition, for the first type of method, the hardness of the flexible substrate is poor, and the device manufacturing is directly performed on the flexible substrate, and its processing accuracy and film quality are affected.

For the second type of method, the device preparation after coating polyimide on the silicon substrate can solve the problems of processing accuracy and film quality, but the types of flexible substrates that can be used are limited

For example, dimethylsiloxane (PDMS), which is commonly used and has good biocompatibility, has a large difference in thermal expansion coefficient from the deposited material, which easily leads to excessive residual stress of the film.

The process of peeling the device from the silicon substrate is also prone to damage to some devices

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