Adjustable film bulk acoustic wave resonator and preparation method thereof

A thin-film bulk acoustic wave and resonator technology, applied in impedance networks, electrical components, etc., can solve the problems of low tunability and large leakage current density of bulk acoustic wave resonators, and achieve low leakage current, improved leakage current, and suitable mediation. The effect of electric constant

Active Publication Date: 2013-02-27
HUAZHONG UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] Aiming at the defects of the prior art, the object of the present invention is to provide a method for preparing an adjustable thin-film bulk acoustic resonator, aiming at solvin...

Method used

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  • Adjustable film bulk acoustic wave resonator and preparation method thereof
  • Adjustable film bulk acoustic wave resonator and preparation method thereof
  • Adjustable film bulk acoustic wave resonator and preparation method thereof

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preparation example Construction

[0028] figure 1 It shows the implementation process of the preparation method of the tunable thin-film bulk acoustic resonator provided by the embodiment of the present invention, specifically including:

[0029] S1: preparing a barrier layer on a clean Si substrate;

[0030] S2: Fabricate a Bragg reflection grating on the barrier layer, and the Bragg reflection grating is composed of films with different acoustic impedances;

[0031] S3: sequentially prepare an adhesion layer and a bottom electrode on the Bragg reflection grating;

[0032] S4: sequentially prepare BST and BZT thin films on the bottom electrode to form BZT, BST and BZT or BST, BZT and BST multilayer heterostructure, and serve as the piezoelectric layer of the bulk acoustic wave resonator;

[0033] S5: annealing the BST and BZT films to form a crystallized film;

[0034] S6: A tunable thin-film bulk acoustic resonator is obtained after preparing the top electrode on the crystallized thin film.

[0035] In t...

Embodiment 1

[0038] (1) A silicon wafer 1 with a crystal phase selected, with a thickness of 0.5 mm, was ultrasonically cleaned in toluene, acetone and absolute ethanol for 5 minutes, and dried with high-purity N2;

[0039] (2) prepare barrier layer 2 with the method for radio frequency magnetron sputtering, the material of barrier layer selects SiO for use;

[0040] (3) Prepare 3 and 4 thin films sequentially on the barrier layer 2 by radio frequency magnetron sputtering to obtain two pairs of Bragg reflection gratings composed of 3 and 4 epitaxial thin films, wherein 3 and 4 can be SiO2, W, SiO2 respectively , Mo or SiO2, Au, etc., the thickness of 3 and 4 is selected according to different materials;

[0041] (4) Prepare the adhesive layer 5 and the bottom electrode 6 successively on the above-prepared Bragg reflection grating with the method of radio frequency magnetron sputtering, wherein the adhesive layer is selected Ti or TiO2, and the bottom electrode is selected Pt or Au etc., a...

Embodiment 2

[0046] (1) A silicon wafer 1 with a crystal phase selected, with a thickness of 0.5 mm, was ultrasonically cleaned in toluene, acetone and absolute ethanol for 5 minutes, and dried with high-purity N2;

[0047] (2) Prepare barrier layer 2, adhesion layer 5 and bottom electrode 6 successively on 1 with the method of radio frequency magnetron sputtering, wherein barrier layer selects SiO2 for use, adhesion layer can select Ti or TiO2 for use, bottom electrode selects Pt or Au for use etc., whose thicknesses are 300nm, 20nm and 100nm respectively;

[0048] (3) Prepare 7 and 8 thin films successively by radio frequency magnetron sputtering to obtain a piezoelectric layer of a bulk acoustic wave resonator composed of 7, 8 and 7 three-layer epitaxial structures. The piezoelectric layer can be BZT, BST and BZT It can also be BST, BZT and BST. The thicknesses of 7 and 8 are 50nm and 200nm respectively. The sputtering parameters of 7 and 8 are: target base distance 70mm, working press...

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Abstract

The invention discloses an adjustable film bulk acoustic wave resonator and a preparation method thereof. The preparation method comprises the following steps: S1, preparing a blocking layer on a clean Si substrate; S2, preparing a Bragg reflecting grating on the blocking layer, wherein the Bragg reflecting grating consists of different acoustic wave impedance films; S3, preparing an adhesion layer and a bottom electrode on the Bragg reflecting grating sequentially; S4, preparing a multi-layer heterogeneous structure on the bottom electrode to serve as a piezoelectric layer of the bulk acoustic wave resonator, wherein the multi-layer heterogeneous structure consists of a barium strontium titanate (BST) film, a barium zirconate titanate (BZT) film or a bismuth zinc niobate (BZN) film; S5, annealing the multi-layer heterogeneous structure to form a crystallized film; and S6, preparing a top electrode on the crystallized film to obtain the adjustable film bulk acoustic wave resonator. The multi-layer heterogeneous structure serves as the piezoelectric layer, so that the bulk acoustic wave resonator has relatively low dielectric loss and leak current, relatively moderate dielectric constant, relatively high adjustability and large optimum value at room temperature.

Description

technical field [0001] The invention belongs to the technical field of bulk acoustic wave resonators, and more specifically relates to an adjustable film bulk acoustic wave resonator and a preparation method thereof. Background technique [0002] With the development of modern wireless communication technology towards high frequency and high speed, people put forward higher requirements for pre-filters commonly used in high frequency communication, such as high performance and microwave integration. The band-pass filters currently used in radio frequency systems mainly include microwave dielectric ceramic filters and surface acoustic wave (SAW) filters. Although the performance of the dielectric ceramic filter is good, there are problems such as large volume and poor process compatibility, which limit its further development. Although the SAW filter has a high Q value and a relatively small geometric size, because the finger width and finger spacing of the interdigitated el...

Claims

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Application Information

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IPC IPC(8): H03H9/17H03H3/02
Inventor 傅邱云周东祥罗为龚树萍胡云香郑志平刘欢赵俊
Owner HUAZHONG UNIV OF SCI & TECH
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