阅读说明：本技术 一种高频声波谐振器及其制备方法 (High-frequency acoustic wave resonator and preparation method thereof ) 是由 欧欣 郑鹏程 张师斌 周鸿燕 黄凯 于 2020-03-31 设计创作，主要内容包括：本申请提供一种高频声波谐振器及其制备方法,该高频声波谐振器包括：高声速支撑衬底；绝缘介质层,绝缘介质层位于高声速支撑衬底的上表面；压电膜,压电膜位于绝缘介质层的上表面；叉指电极,叉指电极位于压电膜的上表面。通过在压电膜下方设置高声速支撑衬底可以增大压电膜中所激发传播的目标弹性波的声速,并可有效约束目标弹性波的传播,提高高频声波谐振器的谐振频率；通过在压电膜与高声速支撑衬底之间设置绝缘介质层,可以有效降低压电膜中电场能量的泄露,可增强高频声波谐振器的机电耦合系数；通过选择合适的绝缘介质层,可以对高频声波谐振器进行温度补偿,降低高频声波谐振器的温漂,提高高频声波谐振器的温度稳定性。(The application provides a high-frequency acoustic wave resonator and a preparation method thereof, and the high-frequency acoustic wave resonator comprises: a high acoustic velocity support substrate; the insulating medium layer is positioned on the upper surface of the high-sound-velocity support substrate; the piezoelectric film is positioned on the upper surface of the insulating medium layer; and the interdigital electrode is positioned on the upper surface of the piezoelectric film. The sound velocity of the target elastic wave excited and propagated in the piezoelectric film can be increased by arranging the high-sound-velocity supporting substrate below the piezoelectric film, the propagation of the target elastic wave can be effectively restrained, and the resonance frequency of the high-frequency acoustic wave resonator is improved; by arranging the insulating medium layer between the piezoelectric film and the high-sound-velocity support substrate, the leakage of electric field energy in the piezoelectric film can be effectively reduced, and the electromechanical coupling coefficient of the high-frequency sound wave resonator can be enhanced; by selecting a proper insulating medium layer, the temperature compensation can be carried out on the high-frequency acoustic wave resonator, the temperature drift of the high-frequency acoustic wave resonator is reduced, and the temperature stability of the high-frequency acoustic wave resonator is improved.)

1. A high frequency acoustic wave resonator, comprising:

a high acoustic speed support substrate (1);

the insulating medium layer (2), the insulating medium layer (2) is positioned on the upper surface of the high-sound-velocity support substrate (1);

the piezoelectric film (3), the piezoelectric film (3) is positioned on the upper surface of the insulating medium layer (2);

the interdigital electrodes (4), the interdigital electrodes (4) are positioned on the upper surface of the piezoelectric film (3);

the ratio of the thickness of the piezoelectric film (3) to the wavelength lambda of a target elastic wave excited by the piezoelectric film (3) is between 0.05 and 0.5;

the resistivity of the insulating medium layer (2) is more than 10¹²Omega cm, the thickness of the insulating medium layer (2) is between 0.01 lambda and lambda.

2. The high frequency acoustic wave resonator according to claim 1, characterized in that the target elastic waves excited by the piezoelectric film (3) include S-waves, SH-waves, Rayleigh (Rayleigh) waves, and a-waves.

3. The high frequency acoustic resonator according to claim 1, characterized in that the material of the high speed support substrate (1) comprises silicon carbide, diamond or sapphire;

the material of the insulating medium layer (2) comprises silicon dioxide, silicon nitride or aluminum oxide;

the material of the piezoelectric film (3) comprises lithium niobate, lithium tantalate, aluminum nitride, quartz or zinc oxide;

the material of the piezoelectric film (3) and the material of the insulating medium layer (2) can be matched and form temperature compensation.

4. The high frequency acoustic wave resonator according to claim 1, characterized in that a ratio of a thickness of the piezoelectric film (3) to a wavelength λ of a target elastic wave excited by the piezoelectric film (3) is between 0.1 and 0.35.

5. The high frequency acoustic wave resonator according to claim 1, characterized in that an acoustic velocity of a bulk wave propagating in the high acoustic velocity support substrate (1) is larger than an acoustic velocity of a target elastic wave propagating in the piezoelectric film (3).

6. A preparation method of a high-frequency acoustic wave resonator is characterized by comprising the following steps:

obtaining a high acoustic velocity support substrate (1);

preparing and forming an insulating medium layer (2) on the upper surface of the high-sound-velocity support substrate (1);

preparing and forming a piezoelectric film (3) on the upper surface of the insulating medium layer (2);

and preparing and forming an interdigital electrode (4) on the upper surface of the piezoelectric film (3).

Wherein the ratio of the thickness of the piezoelectric film (3) to the wavelength λ of a target elastic wave excited by the piezoelectric film (3) is between 0.05 and 0.5;

the resistivity of the insulating medium layer (2) is more than 10¹²Omega cm, the thickness of the insulating medium layer (2) is between 0.01 lambda and lambda.

7. The production method of a high-frequency acoustic wave resonator according to claim 6, characterized in that the target elastic wave excited by the piezoelectric film (3) includes an S wave, an SH wave, a Rayleigh (Rayleigh) wave, and an a wave.

8. The production method for a high frequency acoustic wave resonator according to claim 6, characterized in that the material of the high speed support substrate (1) comprises silicon carbide, diamond or sapphire;

the material of the insulating medium layer (2) comprises silicon dioxide, silicon nitride or aluminum oxide; the forming method of the insulating medium layer comprises a deposition method, an epitaxial method or a thermal oxidation method;

the material of the piezoelectric film (3) comprises lithium niobate, lithium tantalate, aluminum nitride, quartz or zinc oxide;

the piezoelectric film (3) is formed by a deposition method, an epitaxy method, an ion beam stripping method or a bonding method;

the material of the piezoelectric film (3) and the material of the insulating medium layer (2) can be matched and form temperature compensation.

9. The production method of a high frequency acoustic wave resonator according to claim 6, characterized in that the ratio of the thickness of the piezoelectric film (3) to the wavelength λ of the excited target elastic wave is between 0.1 and 0.35.

10. The production method of a high-frequency acoustic wave resonator according to claim 6, characterized in that an acoustic velocity of a bulk wave propagating in the high-acoustic-velocity support substrate (1) is larger than an acoustic velocity of a target elastic wave propagating in the piezoelectric film (3).

Technical Field

The application relates to the technical field of semiconductor preparation, in particular to a high-frequency acoustic wave resonator and a preparation method thereof.

Background

With the development of the internet and 5G technology, the market demand for radio frequency devices continues to grow. The surface acoustic wave filter is widely applied to a radio frequency front end, and the working frequency of the surface acoustic wave filter is mainly determined by the period of an interdigital electrode and the wave velocity of an elastic wave excited in a piezoelectric material. The working frequency of the existing surface acoustic wave filter is generally lower than 3GHz, the FR1 frequency band in 5G communication can reach 6GHz at most, and the existing surface acoustic wave filter has the problems of low resonant frequency, low electromechanical coupling coefficient, temperature drift and the like, so that the requirement of 5G communication cannot be completely met. Although the period of the interdigital electrode is reduced, the working frequency can be improved, the manufacturing cost and the process difficulty are improved, and the performance of the device is also deteriorated.

Disclosure of Invention

The acoustic wave resonator aims to solve the technical problems that in the prior art, the resonant frequency of the acoustic wave resonator is low, the electromechanical coupling coefficient is not high, and temperature drift exists.

In order to solve the above technical problem, an embodiment of the present application discloses a high-frequency acoustic wave resonator, including:

a high acoustic velocity support substrate;

the insulating medium layer is positioned on the upper surface of the high-sound-velocity support substrate;

the piezoelectric film is positioned on the upper surface of the insulating medium layer;

and the interdigital electrode is positioned on the upper surface of the piezoelectric film.

The ratio of the thickness of the piezoelectric film to the wavelength lambda of the target elastic wave excited by the piezoelectric film 3 is between 0.05 and 0.5;

the resistivity of the insulating medium layer is more than 10¹²Omega cm, the thickness of the insulating medium layer is between 0.01 lambda and lambda.

Further, the target elastic waves excited by the piezoelectric film include S waves, SH waves, Rayleigh (Rayleigh) waves, and a waves.

Further, the material of the high-speed support substrate includes silicon carbide, diamond, or sapphire;

the material of the insulating medium layer comprises silicon dioxide, silicon nitride or aluminum oxide;

the material of the piezoelectric film includes lithium niobate, lithium tantalate, aluminum nitride, quartz, or zinc oxide.

The material of the piezoelectric film and the material of the insulating medium layer can be matched and form temperature compensation.

Further, the ratio of the thickness of the piezoelectric film to the wavelength λ of the target elastic wave excited by the piezoelectric film is between 0.1 and 0.35.

Further, the acoustic velocity of a bulk wave propagating in the high acoustic velocity support substrate is greater than the acoustic velocity of a target elastic wave propagating in the piezoelectric film.

The embodiment of the application discloses a preparation method of a high-frequency acoustic wave resonator on the other hand, which is characterized by comprising the following steps:

obtaining a high-acoustic-speed support substrate;

preparing and forming an insulating medium layer on the upper surface of the high-sound-velocity support substrate;

preparing and forming a piezoelectric film on the upper surface of the insulating medium layer;

and preparing and forming an interdigital electrode on the upper surface of the piezoelectric film. (ii) a

The ratio of the thickness of the piezoelectric film to the wavelength lambda of a target elastic wave excited by the piezoelectric film is between 0.05 and 0.5;

the resistivity of the insulating medium layer is more than 10¹²Omega cm, the thickness of the insulating medium layer is between 0.01 lambda and lambda.

Further, the target elastic waves excited by the piezoelectric film include S waves, SH waves, Rayleigh (Rayleigh) waves, and a waves.

Further, the material of the high-speed support substrate includes silicon carbide, diamond, or sapphire;

the material of the insulating medium layer comprises silicon dioxide, silicon nitride or aluminum oxide; the forming method of the insulating medium layer comprises a deposition method, an epitaxial method or a thermal oxidation method;

the material of the piezoelectric film comprises lithium niobate, lithium tantalate, aluminum nitride, quartz or zinc oxide; the piezoelectric film is formed by a deposition method, an epitaxial method, an ion beam lift-off method, or a bonding method.

The material of the piezoelectric film and the material of the insulating medium layer can be matched and form temperature compensation.

The ratio of the thickness of the piezoelectric film to the wavelength λ of the excited target elastic wave is between 0.1 and 0.35.

Further, the acoustic velocity of a bulk wave propagating in the high acoustic velocity support substrate is greater than the acoustic velocity of a target elastic wave propagating in the piezoelectric film.

By adopting the technical scheme, the application has the following beneficial effects:

according to the high-frequency acoustic wave resonator provided by the embodiment of the application, the high-sound-velocity supporting substrate is arranged below the piezoelectric film, so that the sound velocity of the target elastic wave excited and propagated in the piezoelectric film can be increased, the propagation of the target elastic wave can be effectively restrained, and the resonance frequency of the high-frequency acoustic wave resonator can be improved; by arranging the insulating medium layer between the piezoelectric film and the high-sound-velocity support substrate, the leakage of electric field energy in the piezoelectric film can be effectively reduced, and the electromechanical coupling coefficient of the high-frequency sound wave resonator can be enhanced; by selecting a proper insulating medium layer, the temperature compensation can be carried out on the high-frequency acoustic wave resonator, the temperature drift of the high-frequency acoustic wave resonator is reduced, and the temperature stability of the high-frequency acoustic wave resonator is improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic device structure diagram of a high-frequency acoustic wave resonator according to an embodiment of the present application;

fig. 2 is a schematic flow chart of a method for manufacturing a high-frequency acoustic wave resonator according to an embodiment of the present disclosure;

fig. 3 is a top view of interdigital electrodes of a high frequency acoustic wave resonator according to an embodiment of the present application;

FIG. 4 is a graph showing the thickness of an insulating dielectric layer and the electromechanical coupling coefficient of a high-frequency acoustic wave resonator according to an embodiment of the present invention;

the following is a supplementary description of the drawings:

1-a high acoustic velocity support substrate; 2-an insulating dielectric layer; 3-a piezoelectric film; 4-interdigital electrodes.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic may be included in at least one implementation of the present application. In the description of the embodiments of the present application, it is to be understood that the terms "upper", "lower", "top", "bottom", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Moreover, the terms "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a high-frequency acoustic wave resonator according to an embodiment of the present application, where the high-frequency acoustic wave resonator in fig. 1 includes:

a high acoustic velocity support substrate 1;

the insulating medium layer 2, the insulating medium layer 2 locates at the upper surface of the high sound velocity supporting substrate 1;

the piezoelectric film 3 is positioned on the upper surface of the insulating medium layer 2;

the interdigital electrode 4 is positioned on the upper surface of the piezoelectric film 3;

the ratio of the thickness of the piezoelectric film 3 to the wavelength λ of the target elastic wave excited by the piezoelectric film 3 is between 0.05 and 0.5;

the resistivity of the insulating medium layer 2 is more than 10¹²Omega cm, the thickness of the insulating medium layer 2 is between 0.01 lambda and lambda.

In the embodiment of the present application, the target elastic waves excited by the piezoelectric film include S waves, SH waves, Rayleigh (Rayleigh) waves, and a waves.

According to the high-frequency acoustic wave resonator provided by the embodiment of the application, the high-sound-velocity supporting substrate 1 is arranged below the piezoelectric film 3, so that the sound velocity of a target elastic wave excited and propagated in the piezoelectric film 3 can be increased, the propagation of the target elastic wave can be effectively restrained, and the resonance frequency of the high-frequency acoustic wave resonator can be improved; by arranging the insulating medium layer 2 between the piezoelectric film 3 and the high-sound-velocity support substrate 1, the leakage of electric field energy in the piezoelectric film 3 can be effectively reduced, and the electromechanical coupling coefficient of the high-frequency acoustic wave resonator can be enhanced; by selecting the proper insulating medium layer 2, the temperature compensation can be carried out on the high-frequency acoustic wave resonator, the temperature drift of the high-frequency acoustic wave resonator is reduced, and the temperature stability of the high-frequency acoustic wave resonator is improved.

In the embodiment of the present application, the high-frequency acoustic wave resonator is characterized in that: the high-frequency acoustic wave resonator mainly utilizes S waves; the high-frequency acoustic wave resonator can excite and effectively restrain the propagation of S waves; the high-frequency acoustic wave resonator can also utilize SH waves, Rayleigh waves and A waves; the high-frequency acoustic wave resonator can increase the wave velocity of the excited SH wave or Rayleigh wave or a wave (compared with the wave velocity of the intrinsic SH wave or Rayleigh (Rayleigh) wave or a wave in the piezoelectric film 3).

In another aspect, the embodiment of the present application discloses a method for manufacturing the high-frequency acoustic wave resonator, and fig. 2 is a schematic flow chart of the method for manufacturing the high-frequency acoustic wave resonator, where the method includes the following steps:

s1, obtaining the high sound velocity supporting substrate 1;

s2, preparing and forming an insulating medium layer 2 on the upper surface of the high-sound-speed supporting substrate 1; the forming method of the insulating medium layer comprises a deposition method, an epitaxial method or a thermal oxidation method;

s3, preparing and forming a piezoelectric film 3 on the upper surface of the insulating medium layer 2; the formation method of the piezoelectric film 3 includes a deposition method, an epitaxial method, an ion beam peeling method, or a bonding method.

S4, preparing and forming the interdigital electrode 4 on the upper surface of the piezoelectric film 3, which comprises the following steps:

forming an interdigital material layer on the upper surface of the piezoelectric film 3; and forming the interdigital electrode 4 by adopting photoetching and metal deposition processes.

In the embodiments of the present application, the material of the high-speed support substrate includes, but is not limited to, silicon carbide, diamond, or sapphire; in the present embodiment, the material of the high acoustic velocity support substrate 1 is preferably a material having a large thermal conductivity, for example, silicon carbide or diamond.

The material of the insulating dielectric layer 2 includes, but is not limited to, silicon dioxide (SiO)₂) Silicon nitride (Si)₃N₄) Or aluminum oxide (Al)₂O₃)；

The material of the piezoelectric film 3 includes, but is not limited to, lithium niobate (L iNbO)₃) Lithium tantalate (L iTaO)₃) Aluminum nitride (AlN), Quartz (Quartz), or zinc oxide (ZnO).

In the embodiment of the application, the material of the piezoelectric film 3 and the material of the insulating medium layer 2 can be matched and form temperature compensation. In a first practical scheme, when the sound velocity temperature coefficient (TC1) of the insulating medium layer 2 is greater than 0, the sound velocity temperature coefficient (TC2) of the piezoelectric film 3 is less than 0, so as to form temperature compensation; in a second practical scheme, when the sound velocity temperature coefficient of the insulating medium layer 2 is less than 0, the sound velocity temperature coefficient of the piezoelectric film 3 is greater than 0 to form temperature compensation; in the third practical scheme, both the sound velocity temperature coefficient of the insulating medium layer 2 and the sound velocity temperature coefficient of the piezoelectric film 3 are greater than 0, and the sound velocity temperature coefficient of the insulating medium layer 2 is smaller than the sound velocity temperature coefficient of the piezoelectric film 3, so as to form temperature compensation; in a fourth implementable scenario, both the sound velocity temperature coefficient of the insulating medium layer 2 and the sound velocity temperature coefficient of the piezoelectric film 3 are smaller than 0, and the absolute value of the sound velocity temperature coefficient of the insulating medium layer 2 is smaller than the absolute value of the sound velocity temperature coefficient of the piezoelectric film 3, so as to form temperature compensation.

In the embodiment of the present application, the ratio of the thickness of the piezoelectric film 3 to the wavelength of the target elastic wave excited by the piezoelectric film 3 is between 0.05 and 0.5; preferably, the ratio of the thickness of the piezoelectric film 3 to the wavelength of the target elastic wave excited by the piezoelectric film 3 is between 0.1 and 0.35, and in an application scenario, a technician of the thickness of the piezoelectric film 3 may adjust the thickness according to actual needs.

The thickness of the insulating medium layer 2 is between 0.01 lambda and lambda, where lambda is the wavelength of the target elastic wave excited by the piezoelectric film 3. The thickness of the insulating medium layer 2 is related to the thickness of the piezoelectric film 3, the sound velocity temperature coefficient of the piezoelectric film 3 and other factors, and the whole frequency Temperature Coefficient (TCF) and the electromechanical coupling coefficient of the high-frequency acoustic wave resonator can be effectively enhanced by adding the insulating medium layer 2 and adjusting the thickness of the insulating medium layer 2. By selecting the proper insulating medium layer 2, the temperature compensation can be carried out on the high-frequency acoustic wave resonator, the temperature drift of the high-frequency acoustic wave resonator is reduced, and the temperature stability of the high-frequency acoustic wave resonator is improved.

In the embodiment of the present application, the piezoelectric film 3 is a single crystal thin film; the acoustic velocity of a bulk wave propagating in the high-acoustic-velocity support substrate 1 is greater than that of a target elastic wave propagating in the piezoelectric film 3. When the sound velocity of the target elastic wave excited by the piezoelectric film 3 in the high-frequency acoustic wave resonator is slightly larger than the sound velocity of the bulk wave propagating in the high-sound-velocity support substrate 1, the sound velocity of the target elastic wave propagating in the piezoelectric film 3 can be ensured to be smaller than the sound velocity of the bulk wave propagating in the high-sound-velocity support substrate 1 by selecting the piezoelectric film 3 with different cut shapes or changing the propagation direction of the target elastic wave in the piezoelectric film 3.

In the embodiment of the present application, the elastic wave excited by the piezoelectric film 3 may include an S wave (symmetric lamb wave), an SH wave (horizontally polarized transverse wave), a Rayleigh (Rayleigh) wave, or an a wave (anti-symmetric lamb wave).

Fig. 3 is a schematic top view of an interdigital electrode 4 according to an embodiment of the present application, and as shown in fig. 3, the interdigital electrode 4 includes a first fixed portion 41, a first interdigital 42, a first dummy interdigital 45, a second fixed portion 43, a second interdigital 44, and a second dummy interdigital 46, wherein the first fixed portion 41 and the second fixed portion 43 are arranged in parallel and spaced apart; the first finger 42, the first dummy finger 45, the second finger 44 and the second dummy finger 46 are all located between the first fixed portion 41 and the second fixed portion 43, the first finger 42 and the first dummy finger 45 are vertically fixed on the first fixed portion 41 and are arranged at intervals along the extending direction of the first fixed portion 41, and the second finger 44 and the second dummy finger 46 are vertically fixed on the second fixed portion 43 and are arranged at intervals along the extending direction of the second fixed portion 43; first finger 42 is disposed in one-to-one correspondence with second dummy finger 46, second finger 44 is disposed in one-to-one correspondence with first dummy finger 45, and first finger 42 is spaced apart from second dummy finger 46, and second finger 44 is spaced apart from first dummy finger 45. By providing the first and second dummy fingers 45 and 46 in the interdigital electrode 4, the electric field distribution in the piezoelectric film 3 can be changed, and the stray waves formed by resonance in the first and second fixed portions 41 and 42 can be suppressed.

In the embodiment of the present application, the distance between the first finger 42 and the second dummy finger 46 can be set according to actual needs, and the distance between the second finger 44 and the first dummy finger 45 can be set according to actual needs.

In the embodiment of the present application, the ratio of the effective length L1 of the first finger 42 to the width L of the finger electrode 4 may be between 0.4 and 0.8, and the ratio of the effective length of the second finger 44 to the width L of the finger electrode 4 may be between 0.4 and 0.8, it should be noted that the effective length L1 of the first finger 42 refers to the length of the portion where the projection of the first finger 42 along the extending direction of the first fixed portion 41 and the second fixed portion 43 coincides with the projection of the second finger 44 along the extending direction of the first fixed portion 41 and the second fixed portion 43, and the effective length L1 of the second finger 44 refers to the length of the portion where the projection of the second finger 44 along the extending direction of the first fixed portion 41 and the second fixed portion 43 coincides with the projection of the first finger 42 along the extending direction of the first fixed portion 41 and the second fixed portion 43.

An embodiment is described below by way of example based on the above scheme.