Bottom electrode structure of bulk acoustic wave resonator and process method

Abstract

The invention discloses a bottom electrode structure of a bulk acoustic wave resonator and a process method. A cavity is manufactured on a substrate; a bottom electrode layer is manufactured above thecavity; an insulating material layer is applied around the bottom electrode layer so that the surface of the insulating material layer and the surface of the bottom electrode layer are kept flat; thestress consistency of the piezoelectric layer is improved; piezoelectric layers are manufactured on the surfaces of the insulating material layer and the bottom electrode layer so that the piezoelectric layers are not in contact with the substrate; the stress influence of the piezoelectric layers is reduced; the electromechanical coupling coefficient of the device is controlled within the optimalrange; the quality factor of the resonator, the yield of the device and the consistency and reliability of the finished product of the device are improved; the effective resonance area of the deviceis larger and closer to the cavity and does not exceed the cavity; and the size of the device can be reduced by about 5%.

Description

technical field [0001] The present application relates to the field of communication devices, and mainly relates to a bottom electrode structure and a process method of a bulk acoustic wave resonator. Background technique [0002] With the increasingly crowded electromagnetic spectrum and the increase of frequency bands and functions of wireless communication equipment, the electromagnetic spectrum used by wireless communication has grown rapidly from 500MHz to above 5GHz, and it is also necessary for the RF front-end module with high performance, low cost, low power consumption and small size. The demand is increasing day by day. The filter is one of the RF front-end modules, which can improve the transmitted and received signals, and is mainly composed of multiple resonators connected through a topology network structure. Fbar (Thin film bulk acoustic resonator) is a bulk acoustic resonator. The filter composed of it has the advantages of small size, strong integration ca...

AI Technical Summary

Problems solved by technology

[0006] As mentioned above, the film layer in the resonant area of ​​the bulk acoustic wave resonator is easily affected by external or self-stress, which may cause defects such as cracking, tympanic membrane, collapsed membrane, and bending. The stress change of the piezoelectric layer will cause the electromechanical coupling coefficient of the piezoelectric layer The change of the resonator will change the bandwidth of the filter composed of the resonator, which will lead to the difference in the performance of the device and affect the performance of the resonator.

Images