A high-performance film bulk acoustic resonator and its manufacturing method

Abstract

The application discloses a high-performance FBAR (Film Bulk Acoustic Resonator), which has an upwardly raised isolation layer on the entire substrate. A raised air cavity; a lower electrode, a piezoelectric layer and an upper electrode respectively on the isolation layer; a passivation layer covering at least the entire upper electrode and / or the exposed part of the lower electrode on the upper electrode. Compared with the existing FBAR, this application changes the position of the air cavity and the manufacturing process, and also adds an isolation layer with the same size as the substrate on the substrate. This can reduce the requirements on the resistivity of the substrate material, thereby reducing the cost of the substrate; it can also improve the isolation between the substrate and the device without changing the substrate material, thereby increasing the open circuit impedance of the resonator . The present application also adds a passivation layer, which can effectively prevent the influence of the deterioration of the upper electrode and / or the lower electrode on the performance and long-term reliability of the device due to oxidation and the like.

Description

technical field [0001] The present application relates to a thin-film bulk acoustic resonator (FBAR or TFBAR, thin-film bulk acoustic resonator). 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, surface acoustic wave) 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] se...

AI Technical Summary

Problems solved by technology

The contact stress between the substrate 1 and the lower electrode 3 of certain materials is large, which makes the growth structure of the lower electrode 3 poor, resulting in poor performance of the FBAR

[0015] Second, the upper electrode 5 is exposed in the air, which is easy to oxidize, deteriorate, etc., thereby affecting parameters such as the frequency of the FBAR

[0016] Third, in order to form the air cavity 2, a chemical mechanical grinding process is required, which is difficult and expensive

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