Aluminum nitride-based piezoelectric layer structure and manufacturing method

Abstract

The invention provides an aluminum nitride-based piezoelectric layer structure and a manufacturing method, the aluminum nitride-based piezoelectric layer structure comprises a substrate and a piezoelectric layer, and the piezoelectric layer comprises a first aluminum nitride-based piezoelectric film layer and a second aluminum nitride-based piezoelectric film layer which are laminated; in the horizontal direction, the piezoelectric layer is divided into a first area and a second area, in the first area, the second aluminum nitride-based piezoelectric film layer is in direct contact with the first aluminum nitride-based piezoelectric film layer, the polarity of the second aluminum nitride-based piezoelectric film layer is the same as that of the first aluminum nitride-based piezoelectric film layer, and in the second area, the polarity of the second aluminum nitride-based piezoelectric film layer is the same as that of the first aluminum nitride-based piezoelectric film layer. An interface modulation layer is arranged between the second aluminum nitride-based piezoelectric film layer and the first aluminum nitride-based piezoelectric film layer; the polarity of the second aluminum nitride-based piezoelectric film layer is opposite to that of the first aluminum nitride-based piezoelectric film layer. According to the aluminum nitride-based piezoelectric layer structure and the manufacturing method thereof, the piezoelectric layer has the areas with the same polarity and the areas with the opposite polarities at the same time, different resonance can be excited, and different requirements can be met.

Description

Technical Field

[0001] This invention belongs to the field of microelectronics technology and relates to an aluminum nitride-based piezoelectric layer structure and its fabrication method. Background Technology

[0002] Currently, wireless data transmission requires radio frequency (RF) filters with operating frequencies of 5 GHz or higher. The filters used in 5G communication are mainly bulk acoustic wave (BAW) filters and surface acoustic wave (SAW) filters. BAW devices have extremely high Q values ​​(above 4000), operate in frequency bands from 100 MHz to 20 GHz, and offer advantages such as high operating frequency, low insertion loss, high frequency selectivity, high power capacity, and strong electrostatic discharge (ESD) immunity, making them the best solution for future RF front-ends.

[0003] AlN materials possess advantages such as high sound velocity, low loss, and low temperature coefficient, and are widely used in bulk acoustic wave filters. When an alternating voltage is applied to both sides of an AlN piezoelectric film, the piezoelectric effect causes the film to vibrate mechanically, thereby generating bulk acoustic waves. Current technologies use a single-layer AlN piezoelectric layer, resulting in a single resonant frequency that can only meet the application requirements of a specific frequency band, thus limiting its application.

[0004] Therefore, how to provide an aluminum nitride-based piezoelectric layer structure and fabrication method so that the piezoelectric layer has two resonant frequencies at the same time has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an aluminum nitride-based piezoelectric layer structure and a method for fabricating it, so as to solve the problem of the single resonant frequency of single-layer piezoelectric thin films in the prior art.

[0006] To achieve the above and other related objectives, the present invention provides an aluminum nitride-based piezoelectric layer structure, comprising:

[0007] Substrate;

[0008] A piezoelectric layer is located above the substrate, the piezoelectric layer comprising a first aluminum nitride-based piezoelectric thin film layer and a second aluminum nitride-based piezoelectric thin film layer, the second aluminum nitride-based piezoelectric thin film layer being located above the first aluminum nitride-based piezoelectric thin film layer;

[0009] In the horizontal direction, the piezoelectric layer is divided into a first region and a second region. In the first region, the second aluminum nitride-based piezoelectric thin film layer and the first aluminum nitride-based piezoelectric thin film layer are in direct contact. In the second region, an interface modulation layer is provided between the second aluminum nitride-based piezoelectric thin film layer and the first aluminum nitride-based piezoelectric thin film layer.

[0010] In the first region, the second aluminum nitride-based piezoelectric thin film layer and the first aluminum nitride-based piezoelectric thin film layer have the same polarity, while in the second region, the second aluminum nitride-based piezoelectric thin film layer and the first aluminum nitride-based piezoelectric thin film layer have opposite polarities.

[0011] Optionally, the material of the interface modulation layer includes at least one of TiN, Ti2O3, SiO2, SiC, SiN, AlN, Al2O3, AlON, SiON, HfO2, Mo, Mg, MgO, W, and Pt, and the thickness of the interface modulation layer ranges from 0.1 to 100 nm.

[0012] Optionally, the material of the first aluminum nitride-based piezoelectric thin film layer includes aluminum nitride and / or doped aluminum nitride, and the material of the second aluminum nitride-based piezoelectric thin film layer includes aluminum nitride and / or doped aluminum nitride, wherein the doping element in the doped aluminum nitride includes one or more of Ga, Sc, Mg, Hf, Zr, B, Er, Be, Ce, Ti, Si, Ge, Li, As, Nb, Sb, Sn, and Sr.

[0013] Optionally, the thickness of the first aluminum nitride-based piezoelectric thin film layer ranges from 0.01 to 2 μm, and the thickness of the second aluminum nitride-based piezoelectric thin film layer ranges from 0.01 to 2 μm.

[0014] Optionally, the substrate includes a Si substrate, a SiC substrate, a Ge substrate, a sapphire substrate, and a diamond substrate.

[0015] The present invention also provides a method for fabricating the aluminum nitride-based piezoelectric layer structure according to any one of the above claims, comprising the following steps:

[0016] A substrate is provided, and a first aluminum nitride-based piezoelectric thin film layer is formed on the substrate;

[0017] An interface modulation layer is formed on the first aluminum nitride-based piezoelectric thin film layer, and the interface modulation layer exposes the first aluminum nitride-based piezoelectric thin film layer in a predetermined area;

[0018] A second aluminum nitride-based piezoelectric thin film layer covering the interface modulation layer is formed on the first aluminum nitride-based piezoelectric thin film layer.

[0019] Optionally, the step of forming the interface modulation layer includes:

[0020] An interface modulation material layer is formed on the first aluminum nitride-based piezoelectric thin film layer;

[0021] A photoresist layer is formed and patterned on the interface modulation material layer. Using the patterned photoresist layer as a mask, the interface modulation material layer at a preset position is removed, and the remaining interface modulation material layer constitutes the interface modulation layer.

[0022] Remove the photoresist layer.

[0023] Optionally, the method for removing the interface modulation material layer at the preset location includes at least one of dry etching and wet etching.

[0024] Optionally, the step of forming the interface modulation layer includes:

[0025] A hard mask layer is formed and patterned on the first aluminum nitride-based piezoelectric thin film layer, and the patterned hard mask layer exposes the first aluminum nitride-based piezoelectric thin film layer at a predetermined position.

[0026] An interface modulation material layer covering the hard mask layer is formed on the first aluminum nitride-based piezoelectric thin film layer;

[0027] The hard mask layer is stripped away, wherein, during the stripping away of the hard mask layer, the interface modulation material layer located above the hard mask layer is removed, and the remaining interface modulation material layer constitutes the interface modulation layer.

[0028] Optionally, the hard mask layer may be a dielectric mask layer or a metal mask layer.

[0029] As described above, in the aluminum nitride-based piezoelectric layer structure and fabrication method of the present invention, the second aluminum nitride-based piezoelectric thin film layer in the first region has the same polarity as the first aluminum nitride-based piezoelectric thin film layer, and the second aluminum nitride-based piezoelectric thin film layer in the second region has opposite polarities as the first aluminum nitride-based piezoelectric thin film layer. This allows the piezoelectric layer to simultaneously contain regions with the same polarity and regions with opposite polarities, enabling the excitation of different resonances and satisfying different requirements. Attached Figure Description

[0030] Figure 1 The diagram shown is a schematic diagram of the aluminum nitride-based piezoelectric layer structure according to Embodiment 1 of the present invention.

[0031] Figure 2 The diagram shows a substrate provided in Embodiment 2 of the present invention, on which a first aluminum nitride-based piezoelectric thin film layer is formed.

[0032] Figure 3 The diagram shows an interface modulation material layer formed on a first aluminum nitride-based piezoelectric thin film layer in Embodiment 2 of the present invention.

[0033] Figure 4 This is a schematic diagram showing the formation and patterning of a photoresist layer on an interface modulation material layer in Embodiment 2 of the present invention.

[0034] Figure 5 The diagram shown is a schematic diagram of the etched interface modulation material layer in Embodiment 2 of the present invention.

[0035] Figure 6 The diagram shown is a schematic diagram of removing the photoresist layer in Embodiment 2 of the present invention.

[0036] Figure 7 This is a schematic diagram showing the formation of a second aluminum nitride-based piezoelectric thin film layer in Embodiment 2 of the present invention.

[0037] Figure 8 The diagram shows a substrate provided in Embodiment 3 of the present invention, on which a first aluminum nitride-based piezoelectric thin film layer is formed.

[0038] Figure 9 This is a schematic diagram illustrating the formation of a hard mask layer on a first aluminum nitride-based piezoelectric thin film layer in Embodiment 3 of the present invention.

[0039] Figure 10 The diagram shown is a schematic diagram of the formation of the interface modulation material layer in Embodiment 3 of the present invention.

[0040] Figure 11 The diagram shown is a schematic of the removal of the hard mask layer in Embodiment 3 of the present invention.

[0041] Figure 12 This is a schematic diagram of the formation of a second aluminum nitride-based piezoelectric thin film layer in Embodiment 3 of the present invention.

[0042] Component designation explanation

[0043] 1 Substrate

[0044] 2 Piezoelectric layer

[0045] 20 First aluminum nitride-based piezoelectric thin film layer

[0046] 21 Second aluminum nitride-based piezoelectric thin film layer

[0047] 3 Interface Modulation Layer

[0048] 4 Interface Modulation Material Layer

[0049] 5. Photoresist layer

[0050] 6 Hard mask layer Detailed Implementation

[0051] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0052] Please see Figures 1 to 12It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0053] Example 1

[0054] This embodiment provides an aluminum nitride-based piezoelectric layer structure. Please refer to [link / reference]. Figure 1 The aluminum nitride-based piezoelectric layer structure includes a substrate 1 and a piezoelectric layer 2. The piezoelectric layer 2 is located above the substrate 1. The piezoelectric layer 2 includes a first aluminum nitride-based piezoelectric thin film layer 20 and a second aluminum nitride-based piezoelectric thin film layer 21. The second aluminum nitride-based piezoelectric thin film layer 21 is located above the first aluminum nitride-based piezoelectric thin film layer 20. In the horizontal direction, the piezoelectric layer 2 is divided into a first region and a second region. In the first region, the second aluminum nitride-based piezoelectric thin film layer 21 and the first aluminum nitride-based piezoelectric thin film layer 20 are in direct contact. In the second region, an interface modulation layer 3 is disposed between the second aluminum nitride-based piezoelectric thin film layer 21 and the first aluminum nitride-based piezoelectric thin film layer 20. In the first region, the second aluminum nitride-based piezoelectric thin film layer 21 and the first aluminum nitride-based piezoelectric thin film layer 20 have the same polarity. In the second region, the second aluminum nitride-based piezoelectric thin film layer 21 and the first aluminum nitride-based piezoelectric thin film layer 20 have opposite polarities.

[0055] As an example, the substrate 1 can be a Si substrate, SiC substrate, Ge substrate, sapphire substrate, diamond substrate, or any other suitable substrate, selected according to requirements.

[0056] As an example, the direction of the arrows in the diagram indicates the polarization direction. Same polarity means same polarization direction, and opposite polarity means opposite polarization direction. In the first region, the second aluminum nitride-based piezoelectric thin film layer 21 and the first aluminum nitride-based piezoelectric thin film layer 20 have the same polarity. When an alternating voltage is applied to both sides of the piezoelectric layer 2 in the first region, a first-order resonance of the basic structure is excited, resulting in a low resonant frequency. In the second region, the second aluminum nitride-based piezoelectric thin film layer 21 and the first aluminum nitride-based piezoelectric thin film layer 20 have opposite polarities. When an alternating voltage is applied to both sides of the piezoelectric layer 2 in the second region, due to the opposite polarities of the two layers, there is a 180° phase difference in the piezoelectric response to the electrical signal. The inverse piezoelectric effect causes one layer of the second aluminum nitride-based piezoelectric thin film layer 21 and the first aluminum nitride-based piezoelectric thin film layer 20 to be subjected to compressive stress, while the other layer is subjected to tensile stress, thereby suppressing the first-order resonance and exciting higher-order resonances, resulting in a high resonant frequency. That is, the piezoelectric layer 2 simultaneously contains regions with the same polarity and regions with opposite polarities, which can excite different resonances to meet different needs.

[0057] As an example, the first aluminum nitride-based piezoelectric thin film layer 20 is made of aluminum nitride and / or doped aluminum nitride, and the second aluminum nitride-based piezoelectric thin film layer 21 is made of aluminum nitride and / or doped aluminum nitride. In the case of doped aluminum nitride, the doping element includes one or more of Ga, Sc, Mg, Hf, Zr, B, Er, Be, Ce, Ti, Si, Ge, Li, As, Nb, Sb, Sn, and Sr, and the doping concentration is ≤50%.

[0058] As an example, in the first region, the first aluminum nitride-based piezoelectric thin film layer 20 is an N-polar AlN layer, and the second aluminum nitride-based piezoelectric thin film layer 21 is an N-polar AlN layer; in the second region, the first aluminum nitride-based piezoelectric thin film layer 20 is an N-polar AlN layer, and the second aluminum nitride-based piezoelectric thin film layer 21 is an Al-polar AlN layer.

[0059] As an example, the thickness of the first aluminum nitride-based piezoelectric thin film layer 20 ranges from 0.01 to 2 μm, and the thickness of the second aluminum nitride-based piezoelectric thin film layer 21 ranges from 0.01 to 2 μm.

[0060] As an example, the material of the interface modulation layer 3 includes one or more of TiN, Ti2O3, SiO2, SiC, SiN, AlN, Al2O3, AlON, SiON, HfO2, Mo, Mg, MgO, W, and Pt. Due to the presence of the interface modulation layer 3, the surface chemical bond state of the first aluminum nitride-based piezoelectric thin film layer 20 can be changed, resulting in the second aluminum nitride-based piezoelectric thin film layer 21 located in the second region having the opposite polarity to the first aluminum nitride-based piezoelectric thin film layer 20. The thickness of the interface modulation layer 3 ranges from 0.1 to 100 nm, preferably 2 to 5 nm.

[0061] As an example, the number of the first region can be one or more, and the number of the second region can be one or more, depending on the actual needs.

[0062] As described above, in the aluminum nitride-based piezoelectric layer structure of this embodiment, the second aluminum nitride-based piezoelectric thin film layer in the first region has the same polarity as the first aluminum nitride-based piezoelectric thin film layer, and the second aluminum nitride-based piezoelectric thin film layer in the second region has opposite polarities as the first aluminum nitride-based piezoelectric thin film layer. This allows the piezoelectric layer to simultaneously contain regions with the same polarity and regions with opposite polarities, enabling the excitation of different resonances and satisfying different needs.

[0063] Example 2

[0064] This embodiment provides a method for fabricating an aluminum nitride-based piezoelectric layer structure, used to fabricate the aluminum nitride-based piezoelectric layer structure described in Embodiment 1, including the following steps:

[0065] S1: Provide a substrate, and form a first aluminum nitride-based piezoelectric thin film layer on the substrate;

[0066] S2: An interface modulation layer is formed on the first aluminum nitride-based piezoelectric thin film layer, wherein the interface modulation layer exposes a predetermined area of ​​the first aluminum nitride-based piezoelectric thin film layer;

[0067] S3: A second aluminum nitride-based piezoelectric thin film layer covering the interface modulation layer is formed on the first aluminum nitride-based piezoelectric thin film layer.

[0068] The fabrication method of the aluminum nitride-based piezoelectric layer structure of this embodiment will be described in detail below with reference to the specific accompanying drawings.

[0069] First, please refer to Figure 2 Step S1: Provide a substrate 1 and form a first aluminum nitride-based piezoelectric thin film layer 20 on the substrate 1.

[0070] As an example, the substrate 1 can be a Si substrate, SiC substrate, Ge substrate, sapphire substrate, diamond substrate, or any other suitable substrate, selected according to requirements.

[0071] As an example, the material of the first aluminum nitride-based piezoelectric thin film layer 20 includes aluminum nitride and / or doped aluminum nitride. In the case of doped aluminum nitride, the doping element includes one or more of Ga, Sc, Mg, Hf, Zr, B, Er, Be, Ce, Ti, Si, Ge, Li, As, Nb, Sb, Sn, and Sr, and the doping concentration is ≤50%.

[0072] Specifically, in this embodiment, the first aluminum nitride-based piezoelectric thin film layer 20 is an N-polar AlN layer.

[0073] Next, please refer to Figure 6 Step S2: An interface modulation layer 3 is formed on the first aluminum nitride-based piezoelectric thin film layer 20, and the interface modulation layer 3 exposes the first aluminum nitride-based piezoelectric thin film layer 20 in a preset area.

[0074] Specifically, the interface modulation layer 3 exposes the first aluminum nitride-based piezoelectric thin film layer 20 in the first region, and the step of forming the interface modulation layer 3 includes:

[0075] (a) such as Figure 3 As shown, an interface modulation material layer 4 is formed on the first aluminum nitride-based piezoelectric thin film layer 20. The material of the interface modulation material layer 4 includes one or more of TiN, Ti2O3, SiO2, SiC, SiN, AlN, Al2O3, AlON, SiON, HfO2, Mo, Mg, MgO, W, and Pt. The thickness of the interface modulation material layer 4 ranges from 0.1 to 100 nm, preferably 2 to 5 nm.

[0076] (ii) Figure 4 As shown, a photoresist layer 5 is formed and patterned on the interface modulation material layer 4;

[0077] (III) Figure 5 As shown, using the patterned photoresist layer 5 as a mask, the interface modulation material layer 4 located in the first region is removed by dry etching or wet etching, and the remaining interface modulation layer 4 constitutes the interface modulation layer 3.

[0078] (iv) such as Figure 6 As shown, the photoresist layer 5 is removed, and the step of forming the interface modulation layer 3 on the first aluminum nitride-based piezoelectric thin film layer 20 is completed.

[0079] Next, please refer to Figure 7 Step S3: A second aluminum nitride-based piezoelectric thin film layer 21 covering the interface modulation layer 3 is formed on the first aluminum nitride-based piezoelectric thin film layer 20.

[0080] As an example, the material of the second aluminum nitride-based piezoelectric thin film layer 21 includes aluminum nitride and / or doped aluminum nitride. When doped aluminum nitride is used, the doping element includes one or more of Ga, Sc, Mg, Hf, Zr, B, Er, Be, Ce, Ti, Si, Ge, Li, As, Nb, Sb, Sn, and Sr, and the doping concentration is ≤50%. Specifically, in this embodiment, the second aluminum nitride-based piezoelectric thin film layer 21 is an AlN layer.

[0081] As an example, the second aluminum nitride-based piezoelectric thin film layer 21 and the first aluminum nitride-based piezoelectric thin film layer 20 constitute the piezoelectric layer 2.

[0082] As an example, in the region where the second aluminum nitride-based piezoelectric thin film layer 21 and the first aluminum nitride-based piezoelectric thin film layer 20 are in direct contact, the second aluminum nitride-based piezoelectric thin film layer 21 and the first aluminum nitride-based piezoelectric thin film layer 20 have the same polarity; while in the region located in the interface modulation layer 3, the presence of the interface modulation layer 3 can change the surface chemical bond state of the first aluminum nitride-based piezoelectric thin film layer 20, so that the second aluminum nitride-based piezoelectric thin film layer 21 and the first aluminum nitride-based piezoelectric thin film layer 20 have opposite polarities, that is, the piezoelectric layer 2 simultaneously contains regions with the same polarity and regions with opposite polarities.

[0083] Example 3

[0084] This embodiment provides a method for fabricating an aluminum nitride-based piezoelectric layer structure, used to fabricate the aluminum nitride-based piezoelectric layer structure described in Embodiment 1. The fabrication method of the aluminum nitride-based piezoelectric layer structure of this embodiment will be described in detail below with reference to the specific accompanying drawings.

[0085] (a) such as Figure 8 As shown, a substrate 1 is provided, and a first aluminum nitride-based piezoelectric thin film layer 20 is formed on the substrate 1;

[0086] (ii) Figure 9 As shown, a hard mask layer 6 is formed and patterned on the first aluminum nitride-based piezoelectric thin film layer 20. The patterned hard mask layer 6 exposes the first aluminum nitride-based piezoelectric thin film layer 20 at a preset position (second region). The hard mask layer 6 includes a dielectric mask layer or a metal mask layer.

[0087] (III) Figure 10 As shown, an interface modulation material layer 4 covering the hard mask layer 6 is formed on the first aluminum nitride-based piezoelectric thin film layer 20, wherein a portion of the interface modulation material layer 4 is in contact with the first aluminum nitride-based piezoelectric thin film layer 20, and a portion of the interface modulation material layer 4 is in contact with the hard mask layer 6.

[0088] (iv) such as Figure 11As shown, the hard mask layer 6 is peeled off, wherein, when the hard mask layer 6 is peeled off, the interface modulation material layer 4 located above the hard mask layer 6 is removed, and the remaining interface modulation material layer 4 constitutes the interface modulation layer 3.

[0089] (V) such as Figure 12 As shown, a second aluminum nitride-based piezoelectric thin film layer 21 covering the interface modulation layer 3 is formed on the first aluminum nitride-based piezoelectric thin film layer 20.

[0090] In summary, in the aluminum nitride-based piezoelectric layer structure and fabrication method of the present invention, the second aluminum nitride-based piezoelectric thin film layer in the first region has the same polarity as the first aluminum nitride-based piezoelectric thin film layer, while the second aluminum nitride-based piezoelectric thin film layer in the second region has opposite polarities to the first aluminum nitride-based piezoelectric thin film layer. This allows the piezoelectric layer to simultaneously contain regions with the same polarity and regions with opposite polarities, enabling the excitation of different resonances to meet various needs. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0091] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An aluminum nitride-based piezoelectric layer structure, characterized in that, include: Substrate; A piezoelectric layer is located above the substrate, the piezoelectric layer comprising a first aluminum nitride-based piezoelectric thin film layer and a second aluminum nitride-based piezoelectric thin film layer, the second aluminum nitride-based piezoelectric thin film layer being located above the first aluminum nitride-based piezoelectric thin film layer; In the horizontal direction, the piezoelectric layer is divided into a first region and a second region. In the first region, the second aluminum nitride-based piezoelectric thin film layer and the first aluminum nitride-based piezoelectric thin film layer are in direct contact. In the second region, an interface modulation layer is provided between the second aluminum nitride-based piezoelectric thin film layer and the first aluminum nitride-based piezoelectric thin film layer. In the first region, the second aluminum nitride-based piezoelectric thin film layer and the first aluminum nitride-based piezoelectric thin film layer have the same polarity, while in the second region, the second aluminum nitride-based piezoelectric thin film layer and the first aluminum nitride-based piezoelectric thin film layer have opposite polarities.

2. The aluminum nitride-based piezoelectric layer structure according to claim 1, characterized in that: The material of the interface modulation layer includes at least one of TiN, Ti2O3, SiO2, SiC, SiN, AlN, Al2O3, AlON, SiON, HfO2, Mo, Mg, MgO, W, and Pt, and the thickness of the interface modulation layer ranges from 0.1 to 100 nm.

3. The aluminum nitride-based piezoelectric layer structure according to claim 1, characterized in that: The first aluminum nitride-based piezoelectric thin film layer is made of aluminum nitride and / or doped aluminum nitride, and the second aluminum nitride-based piezoelectric thin film layer is made of aluminum nitride and / or doped aluminum nitride, wherein the doped aluminum nitride includes one or more of Ga, Sc, Mg, Hf, Zr, B, Er, Be, Ce, Ti, Si, Ge, Li, As, Nb, Sb, Sn, and Sr.

4. The aluminum nitride-based piezoelectric layer structure according to claim 1, characterized in that: The thickness of the first aluminum nitride-based piezoelectric thin film layer ranges from 0.01 to 2 μm, and the thickness of the second aluminum nitride-based piezoelectric thin film layer ranges from 0.01 to 2 μm.

5. The aluminum nitride-based piezoelectric layer structure according to claim 1, characterized in that: The substrates include Si substrates, SiC substrates, Ge substrates, sapphire substrates, and diamond substrates.

6. A method for fabricating an aluminum nitride-based piezoelectric layer structure as described in any one of claims 1-5, characterized in that, Includes the following steps: A substrate is provided, and a first aluminum nitride-based piezoelectric thin film layer is formed on the substrate; An interface modulation layer is formed on the first aluminum nitride-based piezoelectric thin film layer, and the interface modulation layer exposes the first aluminum nitride-based piezoelectric thin film layer in a predetermined area; A second aluminum nitride-based piezoelectric thin film layer covering the interface modulation layer is formed on the first aluminum nitride-based piezoelectric thin film layer.

7. The method for fabricating an aluminum nitride-based piezoelectric layer structure according to claim 6, characterized in that, The steps for forming the interface modulation layer include: An interface modulation material layer is formed on the first aluminum nitride-based piezoelectric thin film layer; A photoresist layer is formed and patterned on the interface modulation material layer. Using the patterned photoresist layer as a mask, the interface modulation material layer at a preset position is removed, and the remaining interface modulation material layer constitutes the interface modulation layer. Remove the photoresist layer.

8. The method for fabricating an aluminum nitride-based piezoelectric layer structure according to claim 7, characterized in that: The method for removing the interface modulation material layer at a preset location includes at least one of dry etching and wet etching.

9. The method for fabricating an aluminum nitride-based piezoelectric layer structure according to claim 6, characterized in that, The steps for forming the interface modulation layer include: A hard mask layer is formed and patterned on the first aluminum nitride-based piezoelectric thin film layer, and the patterned hard mask layer exposes the first aluminum nitride-based piezoelectric thin film layer at a predetermined position. An interface modulation material layer covering the hard mask layer is formed on the first aluminum nitride-based piezoelectric thin film layer; The hard mask layer is stripped away, wherein, during the stripping away of the hard mask layer, the interface modulation material layer located above the hard mask layer is removed, and the remaining interface modulation material layer constitutes the interface modulation layer.

10. The method for fabricating an aluminum nitride-based piezoelectric layer structure according to claim 9, characterized in that: The hard mask layer is either a dielectric mask layer or a metal mask layer.

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