Thin film bulk acoustic resonator and manufacturing method thereof

Abstract

The invention discloses a thin-film bulk acoustic resonator (FBAR); a cavity is formed in a substrate; a lower electrode, an upper electrode, and a piezoelectric layer positioned between the two electrodes are further arranged above the cavity; the cavity is obtained by firstly filling a sacrificial layer and then removing the sacrificial layer, and the sacrificial layer is made of a material which can be removed with an oxygen plasma etching process; and the lower electrode, the upper electrode and / or the electrode leading-out end adopt one or multiple of aluminum, copper or copper aluminum alloy. The invention further discloses a manufacturing method of the FBAR; the aluminum, the copper or the copper aluminum alloy are adopted as an interconnected metal to form the electrode leading-out end; and the oxygen plasma etching (O<2> Plasma) process is adopted to remove the sacrificial layer to form an air gap of the FBAR. According to the invention, the manufacturing cost is reduced, the reliability of the thin-film bulk acoustic resonator is improved, and the environmental friendliness is embodied.

Description

technical field [0001] The present application relates to a thin-film bulk acoustic resonator (FBAR or TFBAR, Thin-film bulk acoustic resonator), in particular to an air-gap type FBAR. Background technique [0002] Currently, filters used in mobile communications mainly include surface acoustic wave (SAW, surface acoustic wave, also called surface acoustic wave) filters and bulk acoustic wave (BAW, bulk acoustic wave) filters. SAW filters are mainly made of 4-inch and 6-inch lithium niobate (LiNiO 3 ) or lithium tantalate (LiTaO 3 ) wafers, BAW filters are mainly produced on 6-inch and 8-inch silicon wafers. Generally, the larger the wafer size, the more integrated circuits can be produced on the same wafer, and the lower the cost. The material cost of the surface acoustic wave filter and the bulk acoustic wave filter is basically the same, but the overall manufacturing cost of the bulk acoustic wave filter is much higher than that of the surface acoustic wave filter, whi...

AI Technical Summary

Problems solved by technology

Generally, air-gap FBARs cannot use low-cost aluminum (Al) and copper (Cu) as the interconnection metal, but use high-cost gold (Au) as the interconnection metal, which greatly increases its material cost

Moreover, while using hydrofluoric acid to remove the sacrificial layer, other structures of the FBAR device will also be corroded to varying degrees by hydrofluoric acid, resulting in poor reliability of the device

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