Bulk acoustic wave resonator and manufacturing method thereof

Abstract

The application discloses a bulk acoustic wave resonator, which includes a substrate and a resonant functional layer arranged on the substrate. The resonant functional layer and the substrate are surrounded to form a resonant cavity. The resonant functional layer includes a bottom electrode layer formed on the substrate in turn. , a piezoelectric layer and a top electrode layer, and also includes a release cavity formed around the resonant cavity, the release cavity and the resonant cavity are located on different planes and communicate with each other in dislocation. Also disclosed is a method for making a bulk acoustic wave resonator, making one or more grooves on the surface of a substrate, depositing a sacrificial material to fill the grooves and forming a liner covering at least between the grooves on the surface of the substrate Bottom surface and part of the groove sacrificial layer, forming the bottom electrode, piezoelectric layer and top electrode layer in sequence, using the release liquid to release the sacrificial material through the piezoelectric layer from the uncovered area of ​​the bottom electrode layer to the release hole corresponding to the groove . The present application avoids the problem of stress mutation during the release process of the sacrificial layer, and the stability of the cavity structure and the consistency of the resonance performance of the device are significantly improved.

Description

technical field [0001] The present application relates to the field of communication devices, and mainly relates to a bulk acoustic wave resonator and a manufacturing method thereof. Background technique [0002] With the increasingly crowded electromagnetic spectrum, the continuous increase of frequency bands and functions of wireless communication equipment, and the rapid growth of wireless communication electromagnetic spectrum from 500MHz to above 5GHz, people are demanding RF front-end modules with high performance, low cost, low power consumption, and small size. demand is increasing day by day. As one of the RF front-end modules, the filter has the function of improving the transmitted and received signals, and plays a pivotal role in the RF front-end module. FBAR (Thin film bulk acoustic cresonator) is a bulk acoustic wave resonator. It is a filter composed of multiple FBARs connected in a topological network structure. Strong and other characteristics to meet the ...

AI Technical Summary

Problems solved by technology

[0008] The current preparation method of air-gap FBAR cavity will cause a series of problems in the process, especially the release process, such as the collapse of the deposited film on the upper part of the cavity due to poor mechanical stability, energy loss caused by uneven stress distribution of the film layer or tympanic membrane, etc. The problem will greatly reduce the performance of the device or even damage the device

Moreover, most of the new frequency bands of 5G are high-frequency bands above 2.5GHz. In high-frequency bands, the electrode thickness and piezoelectric film thickness of the resonator will be further thinned, and the film stress will be more difficult due to the release of the sacrificial layer during cavity preparation. control, resulting in degraded resonator performance, lower yield, or reliability issues

[0009] With the popularization of 5G frequency bands, the performance requirements of filter devices are higher, and the piezoelectric film doping process has been adopted on a large scale, such as AlN film doped with scandium Sc element (Scandium). The stress becomes larger and more difficult to control, requiring better control of the cavity release process to control the film stress and achieve better resonator performance

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