High-reliability FBAR (thin-film bulk acoustic resonator) and manufacturing method thereof

Abstract

The invention discloses a high-reliability FBAR (thin-film bulk acoustic resonator), which is characterized in that an isolation layer is arranged on the whole substrate, and an air cavity, which sinks downward from the upper surface of the substrate, is arranged between the substrate and the isolation layer; a lower electrode, a piezoelectric layer and an upper electrode are arranged on the isolation layer, and a passivation layer, which at least covers an exposed portion of the whole upper electrode and/or the lower electrode, is arranged on the upper electrode. Compared with an existing FBAR, the FBAR disclosed by the invention is additionally provided with the isolation layer, which is identical to the substrate in size, on the substrate. On the one hand, requirements for a substrate material in the aspect of resistivity can be reduced, thereby reducing the cost of the substrate; and on the other hand, isolation between the substrate and a device can be improved under the premise of not changing the substrate material, thereby improving the open-circuit impedance of the resonator. The FBAR disclosed by the invention is further additionally provided with the passivation layer on the exposed portion of the upper electrode and/or the lower electrode, thereby being capable of effectively preventing influences brought to the device performance and the long-term reliability by modification such as oxidation and the like of the upper electrode and/or the lower electrode.

Description

technical field [0001] The present application relates to a thin-film bulk acoustic resonator (FBAR or TFBAR, thin-filmbulkacousticresonator). Background technique [0002] FBAR is a semiconductor device that mainly includes a piezoelectric material sandwiched between two electrodes, and the three form a sandwich structure. FBAR is often used to make radio frequency filters in wireless devices such as mobile phones. The filter is composed of a group of FBARs, such as half-ladder, full-ladder, lattice, stacked ( stack) and other topological structures, which are used to filter out unwanted frequencies while allowing specific frequencies to pass. FBAR is also used to make duplexers to partially replace early surface acoustic wave (SAW, surfaceacousticwave) devices. Its advantages lie in small size, advanced technology, and improved efficiency. In addition, FBAR is also used to make microwave oscillators, sensors, power amplifiers, low noise amplifiers, etc. [0003] see fi...

AI Technical Summary

Problems solved by technology

Therefore, a small part of the overlapping area between the lower electrode 3 and the upper electrode 5 is not above the air cavity 2, which will cause leakage of sound waves and affect the quality factor of FBAR

[0016] Third, the upper electrode 5 is exposed in the air, which is easy to oxidize, deteriorate, etc., thereby affecting the parameters such as the frequency of the FBAR

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