Bulk acoustic wave resonator and manufacturing method thereof

Abstract

The invention relates to a bulk acoustic wave resonator. The bulk acoustic wave resonator comprises a substrate, wherein the substrate comprises a cavity, an opening of the cavity is located in an upper surface of the substrate, and the bottom of the cavity is sealed by the substrate; a piezoelectric film above the substrate and the cavity; and two groups of interdigital electrodes which are positioned on an upper surface of the piezoelectric film and are staggered with each other. The invention also relates to a preparation method of a bulk acoustic wave resonator.

Description

Technical field [0001] The present invention relates to the field of microelectromechanical, and in particular to a body acoustic resonator and a method of manufacturing the same. Background technique [0002] The filter is used as a radio filter device, directly determines the operating frequency band and bandwidth of the communication device, playing a raised role in the RF front end. [0003] In the 3G / 4G filter market, the filter based on the body acoustic wave (BAW) has the advantages of low insertion loss, high rectangular coefficient, high power capacity, and therefore widely used in contemporary wireless communication systems. However, the emergence of 5G communications, the acoustic filter proposed higher requirements: [0004] (1) 5G NR (New Radio) uses a higher frequency band, the acoustic wave (BAW) filter acoustic and ohmic loss As the operating frequency rises sharply, the increase in the insertion loss of the filter is increased; [0005] (2) 5G NR band N78, N79 ...

AI Technical Summary

Problems solved by technology

[0004] (1) 5G NR (New Radio) uses a frequency band with a higher frequency, and the acoustic and ohmic loss of the bulk acoustic wave (BAW) filter increases sharply with the operating frequency, resulting in an increase in the filter insertion loss;

[0005] (2) 5G NR frequency bands N78, N79, and N77 require bandwidths of 500, 600, and 900MHz, respectively, which are difficult to achieve for mainstream aluminum nitride (AlN)-based bulk acoustic wave (BAW) filters on the market, so Its bandwidth is limited by the electromechanical coupling coefficient of aluminum nitride (AlN)

[0009] However, because the lithium niobate film is very thin, and there is a cavity on the back of the resonator structure that communicates with the outside, resulting in poor structural stability, the lithium niobate film is easily damaged during the packaging and assembly process, affecting performance

In addition, the existing bulk acoustic wave resonator adopts the effective resonance area overlapped with the immovable base area, and the acoustic wave will leak to the substrate, so that the energy will be dissipated to the substrate

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