Air cavity type film bulk acoustic resonator and manufacturing method thereof

Abstract

The invention discloses an air cavity type film bulk acoustic resonator and a manufacturing method thereof. The air cavity type film bulk acoustic resonator comprises a substrate, a SiC support layer,a graphene bottom electrode, a piezoelectric layer and a top electrode, wherein the substrate comprises a first surface and a second surface which are back to each other, the SiC support layer is arranged on the first surface of the substrate, the graphene bottom electrode directly grows on the SiC support layer, at least a local area of the piezoelectric layer covers the graphene bottom electrode, the top electrode is arranged on the piezoelectric layer, and an air cavity is formed on the second surface of the substrate. Compared with the prior art, structure of the air cavity type film bulkacoustic resonator is optimized by the method provided by the invention, thus, stability and reliability of devices can be guaranteed while performance of the devices are improved significantly, andthe manufacturing method of the air cavity type film bulk acoustic resonator is simple and easy to implement in large scale.

Description

technical field [0001] The invention relates to an air cavity type thin film bulk acoustic wave resonator, in particular to an air cavity type thin film bulk acoustic wave resonator and a preparation method thereof. Background technique [0002] Resonators are the core components of duplexers and filters that are widely used in mobile phone RF front-ends. And with the development of communication, the communication bands that need to be simultaneously compatible in mobile phones are constantly increasing, and the number of resonators required is also gradually increasing. The development trend of multifunctional and integrated wireless communication systems and the increase in the number of components have put forward requirements for resonators such as miniaturization, integration, high frequency, and high performance. Traditional microwave resonators, because electromagnetic waves are used as the carrier, require a very large resonator size in the current application comm...

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Problems solved by technology

[0004] The traditional thin film bulk acoustic resonator uses metal as the electrode, which has a large loss. At the same time, since the piezoelectric film is sputtered on the lower electrode, the quality of the film has requirements for the lattice orientation and thickness of the lower electrode, but the thickness of the lower electrode is too large. will affect the effective electromechanical coupling coefficient of the device

[0005] In order to improve the performance of thin film bulk acoustic resonator, some researchers try to use graphene as the bottom electrode to reduce the device loss, but the formed device still has the following problems, for example: (1) There is no support layer in the device, which will seriously reduce the reliability of the device (2) The quality of graphene transferred or directly grown on the sacrificial layer is too poor to meet the needs of electrodes; (3) the quality of AlN grown on poor-quality graphene is also difficult to meet the device requirements; (4) ) when patterning AlN, single-layer or multi-layer graphene is easily over-etched

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