Film bulk acoustic resonator and preparation method thereof

Abstract

The invention provides a film bulk acoustic resonator and a preparation method thereof. The preparation method includes the steps: S101, etching one side of the substrate to form a groove, and forminga first sacrificial layer filling the groove in the groove; S102, enabling a supporting layer which is not covered with the first sacrificial layer to grown on the side, provided with the groove opening, of the substrate, and forming a second sacrificial layer on the side, away from the substrate, of the first sacrificial layer; S103, releasing the first sacrificial layer, forming a bottom electrode covering the second sacrificial layer on one side, far away from the substrate, of the support layer, and forming a piezoelectric film on the bottom electrode far away from the second substrate; and S104, forming a top electrode on one side, far away from the bottom electrode, of the piezoelectric film, and releasing the second sacrificial layer. The two sacrificial layers are formed in the groove, so that interconnection between the substrate and the bottom electrode is avoided, damage of the manufacturing process to a core structure is small, introduction of parasitic capacitance is avoided, controllability is high, meanwhile, the manufacturing process of the film bulk acoustic resonator is reduced, consumption of resources and time is reduced, and the production cost is reduced.

Description

technical field [0001] The invention relates to the technical field of thin-film bulk acoustic resonators, in particular to a thin-film bulk acoustic resonator and a preparation method. Background technique [0002] Film Bulk Acoustic Resonator (FilmBulk Acoustic Resonator, referred to as "FBAR") is a new type of filter. Compared with the surface acoustic wave filter, it is not only small in size, large in power capacity, can be integrated, and has a high operating frequency, but also has more Good out-of-band rejection and insertion loss are widely used in current 5G communications. [0003] When preparing a thin film bulk acoustic resonator, a sacrificial layer needs to be formed in the groove, and the traditional sacrificial layer is a one-step release type. However, if the metal grows directly on the sacrificial layer, when the sacrificial layer is released, due to the pressure difference between the inside and outside, the metal will be easily adsorbed to the groove, m...

AI Technical Summary

Problems solved by technology

However, if the metal grows directly on the sacrificial layer, when the sacrificial layer is released, due to the pressure difference between the inside and outside, the metal will be easily adsorbed to the groove, making the substrate and the bottom electrode form an interconnection, causing damage to the core structure of the product , causing product preparation failure

In order to avoid this situation, it is often necessary to increase the thickness of the film and set up complex structures or processes, consuming a lot of resources and time

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