Film layer structure, manufacturing method thereof and filter comprising film layer structure

Abstract

The invention belongs to the technical field of film bulk acoustic wave filter processes, and particularly provides a film layer structure, a manufacturing method thereof and a filter comprising the film layer structure. The film layer structure comprises a substrate, a cavity is formed in the top of the substrate, a composite upper electrode and a composite lower electrode are prepared above thesubstrate, and a piezoelectric layer is arranged between the composite upper electrode and the composite lower electrode; wherein the composite upper electrode comprises an upper electrode, a first temperature compensation layer and an upper electrode insertion layer which are arranged from top to bottom; and the composite lower electrode comprises a lower electrode insertion layer, a second temperature compensation layer and a lower electrode which are arranged from top to bottom. Through the film layer structure provided by the invention, the C-axis preferred orientation growth of the piezoelectric film is facilitated, the piezoelectric film with good orientation and complete crystal grain growth is obtained, and in addition, a filter adopting the film layer structure can be ensured to have relatively low insertion loss and keep bandwidth stable.

Description

technical field [0001] The invention relates to a film layer structure and technology of a high-temperature-stable thin-film bulk acoustic wave filter (TC-FBAR), and belongs to the technical field of thin-film bulk acoustic wave filter technology. Background technique [0002] With the continuous improvement of the operating frequency, sensitivity and integration of military electronic equipment, phased array radar, electronic countermeasures and communication systems have put forward an urgent need for filters with frequency temperature coefficient, high performance and small size. Thin film bulk acoustic wave filter is used in the RF front-end to isolate and gate the RF signal, limit the radiation signal of the transmitter in its operating frequency band, and prevent the interference of the received noise signal. It is a key device in the RF system. It plays a vital role in the competition for control of electromagnetic power. At present, the frequency temperature coeffic...

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Problems solved by technology

However, this approach is not feasible in practical applications

In 2008, Brice Ivira added SiO to the piezoelectric reactor 2 to achieve temperature compensation, but SiO 2 The lattice does not match with the piezoelectric material, and the stress is not easy to control, which will lead to the deterioration of the preferred orientation of the piezoelectric material and affect the insertion loss of the filter

Qiang Zhou et al proposed to embed SiO in the electrode 2 Thin film method, the SiO needed to make the temperature compensation effect good 2 If the thickness is thicker, the effective electromechanical coupling coefficient will drop significantly.

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