CN111510100A - A piezoelectric resonator based on gallium oxide thin film and its preparation method - Google Patents

Abstract

The invention discloses a piezoelectric resonator based on a gallium oxide film and a preparation method thereof, and relates to semiconductor technology. Aiming at the problem that the electromechanical coupling coefficient is not high in the prior art, this solution is proposed, including a substrate with a hollow in the middle, and a piezoelectric film fixed on the substrate. The piezoelectric film is provided with electrodes at the corresponding positions of the hollow of the substrate. Yes, the electrode pair is electrically connected to the piezoelectric film, and the piezoelectric film is made of gallium oxide material. The advantage is that the piezoelectric resonator has a high electromechanical coupling coefficient by utilizing the extremely strong piezoelectric properties of gallium oxide. Further, the use of ε-phase gallium oxide single crystal film can not only avoid energy absorption caused by grain boundaries and defects, reduce losses, but also greatly improve device stability. In addition, the thin film piezoelectric resonator of the present invention has a simple structure and good processing repeatability, which is favorable for industrial production.

Description

A piezoelectric resonator based on gallium oxide thin film and its preparation method

technical field

The invention relates to semiconductor technology, which is a new generation of information technology, in particular to a piezoelectric resonator based on a gallium oxide film and a preparation method thereof.

Background technique

Piezoelectric resonators are widely used to construct RF filters and oscillators, and are one of the important devices in the field of RF communications; in addition, piezoelectric resonators can also be used to implement sensors. With the rapid development of communication technology, the era of big data and the Internet of Things has arrived, and the development direction of piezoelectric resonators is bound to be high frequency, low power consumption, miniaturization, integration and low cost. Thin-film piezoelectric resonators have unmatched frequency, power capacity, volume, and cost advantages over traditional ceramic dielectric resonators. The thin film piezoelectric resonator is usually composed of a piezoelectric film and an electrode. Its working principle is that a radio frequency electrical signal excites an acoustic wave in the piezoelectric film through the electrode to achieve resonance at a specific frequency. Therefore, the electromechanical coupling coefficient of the piezoelectric film is the key to determine the performance of the resonator. Existing piezoelectric thin films are usually prepared by magnetron sputtering process, such as ZnO, AlN, etc. The piezoelectric properties of the materials themselves are not strong enough and they are polycrystalline structures, and there are a large number of grain boundaries and defects, which cause the absorption of acoustic wave oscillation energy. , increasing the loss, resulting in a low electromechanical coupling coefficient. In addition, the large number of grain boundaries and defects in polycrystalline piezoelectric films can also lead to problems such as poor stability and high temperature resistance of the resonator.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned problems in the prior art, the present invention aims to provide a piezoelectric resonator based on a gallium oxide film and a preparation method thereof.

A piezoelectric resonator based on a gallium oxide film according to the present invention includes a substrate hollowed out in the middle, and a piezoelectric film fixed on the substrate. An electrode pair, the electrode pair is electrically connected with the piezoelectric film, and the piezoelectric film is a gallium oxide film.

The gallium oxide film is an ε-phase gallium oxide single crystal film.

The thickness of the gallium oxide film is 0.1um to 20um.

The electrode pair includes a first electrode and a second electrode, the first electrode is arranged on the upper surface of the gallium oxide film, and the second electrode is arranged on the lower surface of the gallium oxide film.

The electrode pair includes a first electrode and a second electrode, and the first electrode and the second electrode are both arranged on the upper surface of the gallium oxide film and form an interdigitated electrode structure.

The method for preparing a piezoelectric resonator based on a gallium oxide film according to the present invention includes the steps of growing the piezoelectric film on the substrate, the step of etching the substrate and hollowing out, and the step of making electrode pairs; The electric thin film is made of gallium oxide material.

The piezoelectric film is an ε-phase gallium oxide single crystal film.

The thickness of the piezoelectric film is 0.1 um to 20 um.

The piezoelectric thin film is epitaxially grown by metal organic chemical vapor deposition or molecular beam epitaxy.

The step of etching and hollowing out the substrate is specifically: forming a patterned mask on the lower surface of the substrate by a photolithography process, and using a dry or wet etching process to etch the substrate, exposing the piezoelectric in the middle position. film.

The piezoelectric resonator based on a gallium oxide film and its preparation method according to the present invention have the advantages that the piezoelectric resonator has a high electromechanical coupling coefficient by utilizing the extremely strong piezoelectric properties of gallium oxide. Further, the use of ε-phase gallium oxide single crystal film can not only avoid energy absorption caused by grain boundaries and defects, reduce losses, but also greatly improve device stability. In addition, the thin-film piezoelectric resonator of the present invention has a simple structure and good processing repeatability, which is favorable for industrial production.

Description of drawings

1 is a schematic structural diagram of Embodiment 1 of the piezoelectric resonator according to the present invention;

FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1 .

3 is a schematic structural diagram of Embodiment 2 of the piezoelectric resonator according to the present invention;

FIG. 4 is a sectional view taken along the line B-B in FIG. 1 .

Reference numerals: 101-substrate, 102-gallium oxide film, 103-first electrode, 104-second electrode.

Detailed ways

Example 1

As shown in FIGS. 1 and 2 , a gallium oxide-based thin film according to the present invention includes a substrate 101 with a hollow in the middle, and a piezoelectric thin film fixed on the substrate 101 . The piezoelectric film is provided with electrode pairs at corresponding positions of the hollowed-out substrate 101 , and the electrode pairs are electrically connected to the piezoelectric film. The piezoelectric film is a gallium oxide film 102, preferably an ε-phase gallium oxide single crystal film, with a thickness of 0.1 um to 20 um. The electrode pair includes a first electrode 103 and a second electrode 104 . The first electrode 103 is disposed on the upper surface of the gallium oxide film 102 , and the second electrode 104 is disposed on the lower surface of the gallium oxide film 102 .

The working principle is that the input and output of electrical signals are realized by the first electrode 103 and the second electrode 104 respectively arranged on the upper and lower surfaces of the gallium oxide film 102 by using the longitudinal piezoelectric effect. The advantages are that the piezoelectric effect is strong and the loss is small.

The preparation method includes the following detailed steps:

Growth of piezoelectric film: epitaxial growth of ε-phase gallium oxide single crystal film by metal organic chemical vapor deposition MOCVD or molecular beam epitaxy MBE on the substrate 101, the thickness is controlled in the preferred range of 0.1um to 20um;

Making the first electrode 103: the first electrode 103 is prepared on the upper surface of the piezoelectric film by sputtering or electron beam evaporation;

Substrate 101 deep groove etching: a patterned mask is formed on the lower surface of the substrate 101 by a photolithography process, and a dry or wet etching process is used to etch the substrate 101 to expose the piezoelectric film in the middle position ;

Fabrication of the second electrode 104: The second electrode 104 is fabricated on the lower surface of the exposed piezoelectric film by sputtering or electron beam evaporation.

Embodiment 2

As shown in FIGS. 3 and 4 , the main difference between this embodiment and the first embodiment is that the electrode pair is the first electrode 103 and the second electrode 104 which are interdigitated electrode structures, and the electrode pairs are both arranged in the oxidized The horizontal position of the upper surface of the gallium thin film 102 is adapted to the position corresponding to the hollow of the substrate 101 .

The working principle is that the input and output of electrical signals are realized by the electrode pair located on the upper surface of the gallium oxide film 102 by using the lateral piezoelectric effect, which has the advantages of simple structure and few preparation process steps.

The preparation method includes the following detailed steps:

Growth of piezoelectric film: epitaxial growth of ε-phase gallium oxide single crystal film by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) method on the substrate 101, the thickness is controlled in the preferred range of 0.1um to 20um;

Making an electrode pair: the first electrode 103 and the second electrode 104 are respectively prepared on the upper surface of the piezoelectric film by sputtering or electron beam evaporation;

Substrate 101 deep groove etching: a patterned mask is formed on the lower surface of the substrate 101 by a photolithography process, and a dry or wet etching process is used to etch the substrate 101 to expose the piezoelectric film in the middle position . Compared with the first embodiment, the steps of forming the electrode pair are more normalized, so that the structure is simple and the process steps are reduced.

For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims (10)

1. The piezoelectric resonator based on the gallium oxide thin film comprises a substrate (101) with a hollow middle part and a piezoelectric thin film fixedly arranged on the substrate (101), wherein an electrode pair is arranged at the corresponding position of the hollow middle part of the substrate (101) of the piezoelectric thin film and is electrically connected with the piezoelectric thin film, and the piezoelectric thin film is the gallium oxide thin film (102).

2. The piezoelectric resonator based on gallium oxide thin film according to claim 1, characterized in that the gallium oxide thin film (102) is a phase gallium oxide single crystal thin film.

3. The piezoelectric resonator based on a gallium oxide thin film according to claim 1, wherein the thickness of the gallium oxide thin film (102) is 0.1um to 20 um.

4. The piezoelectric resonator based on a gallium oxide thin film according to claim 1, wherein the electrode pair comprises a first electrode (103) and a second electrode (104), the first electrode (103) is disposed on the upper surface of the gallium oxide thin film (102), and the second electrode (104) is disposed on the lower surface of the gallium oxide thin film (102).

5. The piezoelectric resonator based on the gallium oxide thin film according to claim 1, wherein the electrode pair comprises a first electrode (103) and a second electrode (104), and the first electrode (103) and the second electrode (104) are both disposed on the upper surface of the gallium oxide thin film (102) and are in an interdigital electrode structure.

6. A preparation method of a piezoelectric resonator based on a gallium oxide film comprises the steps of growing the piezoelectric film on a substrate (101), etching and hollowing the substrate (101) and manufacturing an electrode pair; the piezoelectric film is characterized in that the piezoelectric film is made of gallium oxide materials.

7. The production method according to claim 6, wherein the piezoelectric thin film is a phase gallium oxide single crystal thin film.

8. The production method according to claim 6, wherein the thickness of the piezoelectric thin film is 0.1um to 20 um.

9. The method according to claim 6, wherein the piezoelectric film is epitaxially grown by metal organic chemical vapor deposition or molecular beam epitaxy.

10. The preparation method according to claim 6, wherein the step of etching the substrate (101) to make a hollow is as follows: a patterned mask is formed on the lower surface of the substrate (101) through a photoetching process, and the substrate (101) is etched through a dry etching process or a wet etching process to expose the piezoelectric film in the middle position.

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