Tunable film bulk acoustic resonator

Abstract

The invention belongs to microelectronic technology and in particular to a tunable film bulk acoustic resonator (FBAR) comprising a substrate, a cavity, a bottom electrode layer, a tuning layer and apiezoelectric oscillation stack. The piezoelectric oscillation stack comprises an intermediate electrode layer, a piezoelectric layer, and a top electrode layer. A DC bias voltage is applied to the intermediate electrode layer and the bottom electrode layer. The FBAR DC bias voltage is applied to the bottom electrode and the intermediate electrode, the tuning layer has a piezoelectric characteristic, and the bottom electrode layer is in an annular shape. Thus, under a low DC bias voltage, the FBAR can produce a large offset displacement, resulting in a large change in characteristic frequency.Therefore, the large resonance frequency adjustment of the FBAR can be realized at a low voltage, thereby greatly expanding the application range of the FBAR.

Description

technical field [0001] The invention belongs to the technical field of microelectronics, and in particular relates to a tuneable film bulk acoustic wave resonator. Background technique [0002] With the rapid development of wireless communication, wireless signals are becoming more and more crowded, and new requirements such as integration, miniaturization, low power consumption, high performance, and low cost are put forward for filters working in the radio frequency band. Traditional surface acoustic wave filters will be increasingly unable to meet such standards due to limitations in frequency and power. Film bulk acoustic resonator (FBAR) has gradually become a hot spot in the research of radio frequency filters due to its characteristics of CMOS process compatibility, high quality factor Q value, low loss, low temperature coefficient, and high power carrying capacity. [0003] The resonant frequency of FBAR is determined by its thickness, and its thickness must be prec...

AI Technical Summary

Problems solved by technology

However, when tuning with external components, the value of capacitance and inductance of the external components has a great influence on the performance of FBAR

In the patent CN103326692 A of Dong Shurong et al., an electrically tuned thin film bulk acoustic resonator is proposed. Although the external discrete components are avoided, the resonant frequency of the FBAR is adjusted by applying a DC bias voltage, but it uses a single-layer laminate. The electric layer, the tuning is not enough and the circuit is more complicated

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