Embedded electrode lateral field excitation-based film bulk acoustic resonator (FBAR) and manufacturing method thereof

Abstract

The invention discloses an embedded electrode lateral field excitation-based film bulk acoustic resonator (FBAR), which comprises a substrate and a substrate layer consisting of a mask layer laid at the bottom of the substrate. A support film layer is laid on the top of the substrate. A through hole is reserved in the substrate layer. A piezoelectric film layer is laid on the support film layer. At least a pair of metal electrodes is embedded into the piezoelectric film layer. The invention also discloses a manufacturing method for the FBAR. According to the FBAR, a parasitic mode spectrum can be displaced, so that the FBAR has a high quality factor and pure shear wave mode resonance, has high sensitivity and high resolution in specific application, can maintain a high Q value in a liquid phase environment, and is particularly applied to the field of biosensing.

Description

technical field [0001] The invention belongs to the technical field of piezoelectric sensing, and in particular relates to an FBAR based on embedded electrode lateral field excitation and a manufacturing method thereof. Background technique [0002] Film Bulk Acoustic Resonator (FBAR) is a popular piezoelectric resonance and piezoelectric sensing technology in recent years. Its working principle is similar to that of a quartz crystal oscillator, except that the piezoelectric layer is prepared by a thin film deposition process instead of the crystal oscillator. Quartz sheet cutting and thinning technology. FBAR is prepared by radio-frequency micro-mechanical technology and can be used in fields such as radio-frequency filters and radio-frequency sensors. FBAR can be divided into longitudinal wave mode and shear wave mode according to the working mode. The longitudinal wave mode is often used in radio frequency filter applications, while the shear wave mode is often used in r...

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Problems solved by technology

The Chinese patent whose publication number is CN101257287A discloses a piezoelectric crystal resonator electrode shape design method and the Chinese patent whose publication number is CN101520436A discloses a piezoelectric bulk acoustic wave sensor with elliptical electrodes. In this mode, the quality factor has been improved by optimizing the design of the electrodes; however, it is still unable to solve the problem of excessive spurious interference caused by clutter such as upper surface waves, subsurface waves, and spurious longitudinal waves generated by the spurious vibrations excited by the shear mode lateral field. question

[0005] The Chinese patent with the publication number CN101800524A discloses a shear mode FBAR with an asymmetric interdigitated structure. This structure reduces the spurious interference to a certain extent, but it still cannot completely eliminate the spurious interference, and the main resonance frequency is still suppressed by the spurious Mode interference, main shear wave, longitudinal wave and other parasitic waves exist simultaneously to make the resonance mode impure and the frequency resolution poor. The existence of these problems seriously affects the Q value of the device and the accuracy of frequency detection. In the design of a resonant sensor as a sensitive element, the above two indicators are key parameters that affect the performance of the sensor; and this complex structure is not conducive to production

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