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 comprises the following steps: providing a first substrate and a second substrate; forming a first groove in the first substrate; forming at least one group of longitudinal Bragg reflection gratings on the second substrate, wherein each group of longitudinal Bragg reflection gratings comprises at least two thin film material layers with different acoustic impedances; bonding the side, provided with the longitudinal Bragg reflection grating, of the second substrate with the side, provided with the first groove, of the first substrate; forming a piezoelectric stacking structure on one side, deviating from the first substrate, of the second substrate; and forming at least one group of transverse reflection grids in the edge area of the piezoelectric stack structure to complete the preparation of the film bulk acoustic wave resonator. The prepared film bulk acoustic resonator is provided with reflecting gates in the transverse direction and the longitudinal direction, acoustic energy can be limited in an effective area of a device, the energy trapping effect can be achieved, the Q value of the device can be further improved, and therefore the resonator has high frequency stability.

Description

technical field [0001] The invention relates to a resonator, in particular to a film bulk acoustic wave resonator and a preparation method thereof. Background technique [0002] At present, the most mainstream implementation methods of radio frequency filters are Surface Acoustic Wave (Surface Acoustic Wave, SAW) filters and filters based on Film Bulk Acoustic Resonator (Film Bulk Acoustic Resonator, FBAR) technology. Due to its own limitations, the SAW filter is more suitable for use below 1.5GHz. However, the current wireless communication protocol has long used a frequency band greater than 2.5GHz, and at this time a filter based on FBAR technology must be used. [0003] There are many structures and preparation methods of FBAR devices. In the past structures and preparation methods, silicon is often used as the support structure, PSG is used as the sacrificial layer material, and finally an air gap is formed by etching the PSG sacrificial layer. In an ideal situation, ...

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Problems solved by technology

Since the acoustic impedance mismatch formed in this way is not complete, although the leakage of acoustic energy can be reduced to a certain extent, there will still be acoustic energy leaking horizontally and vertically

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