Preparation method for film bulk acoustic wave resonator

Abstract

The invention relates to the technical field of a film bulk acoustic wave resonator and specifically relates to a preparation method for the film bulk acoustic wave resonator. According to the method, wafer bonding is carried out through adoption of polymer; SiO<2> hydrophilic bonding frequently used by a traditional ion injection stripping method is replaced; an electrode covered by the polymer can be patterned according to a design of the film bulk acoustic wave resonator. The polymer has fluidity, so the polymer can be flattened under the effect of pressure in a wafer bonding process; and the patterned electrode can be nested into the polymer and the stripping of LiNbO<3> single crystal film is not influenced, so the problem that the electrode is difficult to pattern in a bonding transfer process of the single crystal film is solved. The polymer is taken as an acoustic reflection layer of the film bulk acoustic wave resonator, the problem that an air resonant cavity is low in structure strength and a Bragg acoustic reflection cavity is high in preparation difficulty is solved, a preparation technology of a device is simple, and the prepared device is high in structure strength.

Description

technical field [0001] The invention relates to the technical field of thin-film bulk acoustic wave resonators, in particular to a method for preparing a single-crystal piezoelectric thin-film type bulk acoustic wave resonator with a solid-state acoustic reflection layer. Background technique [0002] A film bulk acoustic resonator (FBAR) is a piezoelectric thin film resonator. The basic structure of the film bulk acoustic resonator is a laminated structure consisting of an upper electrode, a piezoelectric layer and a lower electrode on the substrate; in order to suppress the dissipation of vibration energy, a cavity or a Bragg reflection layer is provided below the laminated structure. There are two methods for preparing the cavity: one is to etch the substrate area under the stacked structure, and the etching is carried out from the back of the substrate; the other is to make a patterned surface sacrificial layer on the surface of the substrate, and after preparing the sta...

AI Technical Summary

Problems solved by technology

[0006] However, due to the hydrophilic bonding to SiO 2 The surface flatness of the bonding layer is very high, so it is difficult to pattern the bottom electrode in the bulk acoustic wave resonator stack structure, otherwise the SiO grown on the patterned bottom electrode 2 The bonding layer will show large surface fluctuations, which is difficult to meet the needs of hydrophilic bonding

And due to SiO 2 The thickness of the bonding layer is usually less than 2μm, if the SiO 2 Layer chemical mechanical polishing (CMP), it is easy to cause damage to the lower electrode

Since the lower electrode pattern of the thin film bulk acoustic resonator needs to be specially designed to achieve the effect of suppressing clutter, but the preparation of LiNbO by hydrophilic bond transfer 3 Piezoelectric layer technology is difficult to prepare patterned thin film bulk acoustic resonator stack structure

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