A surface acoustic wave filter based on periodic ferroelectric domains and a method for implementing the same

Abstract

This invention discloses a surface acoustic wave (SAW) filter based on periodic ferroelectric domains and its implementation method. The invention employs a ferroelectric domain polarizer to cause polarization reversal in a ferroelectric semiconductor thin film. Multiple concentric ring-shaped narrow ferroelectric domains with alternating ferroelectric polarization directions are formed beneath the ferroelectric semiconductor thin film between two adjacent polarization electrodes, resulting in a periodic ferroelectric domain thin film. A sheet-like filter input electrode is formed on the periodic ferroelectric domain thin film. Upon receiving an in-phase voltage, the ferroelectric domains with opposite polarization directions automatically generate oscillations in opposite directions, forming a surface acoustic wave standing wave. The operating frequency of the filter is determined by the width of the narrow ferroelectric domains, which is modulated by the voltage and frequency of the applied amplitude-modulated alternating current. Narrow ferroelectric domains with smaller widths are easier to fabricate; therefore, the operating frequency of the filter in this invention is not limited and can operate at higher frequencies. This invention has applications in fields such as radio frequency communication and 6G network transmission, high-precision radar, and remote sensing monitoring.

Description

Technical Field

[0001] This invention relates to semiconductor device fabrication technology, specifically to a surface acoustic wave filter based on periodic ferroelectric domains and its implementation method. Background Technology

[0002] Surface acoustic wave (SAW) filters are crucial components in wireless communication technology. With the development of 5G and 6G technologies, there is an urgent need for a high-frequency SAW filter that is easy to fabricate and has stable performance. Currently, traditional SAW filters input radio frequency signals to a piezoelectric semiconductor thin film via interdigitated electrodes, subsequently generating SAW waves on the film surface. The operating frequency of traditional SAW filters is inversely proportional to the minimum linewidth of the interdigitated electrodes. Therefore, the operating frequency of these devices is limited by the fabrication precision of the interdigitated electrodes, making it difficult to exceed 3 GHz. Furthermore, reducing the linewidth of the interdigitated electrodes to achieve higher operating frequencies leads to decreased device stability and power tolerance.

[0003] Ferroelectric materials are piezoelectric materials with spontaneous polarization properties. Ferroelectric semiconductor thin films not only exhibit the piezoelectric effect but also spontaneously polarize without an applied external electric field. The direction of this spontaneous polarization can be reversed and reoriented under the influence of an external electric field. Within the ferroelectric semiconductor thin film, regions with consistent spontaneous ferroelectric polarization directions are called ferroelectric domains. Applying a designed external electric field to the surface of the ferroelectric semiconductor thin film can form a special ferroelectric domain structure both on the surface and inside the film. If the piezoelectric semiconductor thin film in a traditional surface acoustic wave (SAW) filter can be replaced with a ferroelectric semiconductor thin film with a special ferroelectric domain structure, and the electrode structure of the SAW filter can be redesigned, it will be possible to completely abandon the traditional interdigitated electrode structure and break the limitation of the interdigitated electrode linewidth on the device's operating frequency. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention proposes a method for implementing a surface acoustic wave filter based on periodic ferroelectric domains.

[0005] One objective of this invention is to provide a method for implementing a surface acoustic wave filter based on periodic ferroelectric domains.

[0006] The implementation method of the surface acoustic wave filter based on periodic ferroelectric domains of the present invention includes the following steps:

[0007] 1) Fabrication of ferroelectric domain polarizers:

[0008] The ferroelectric domain polarizer comprises multiple concentric ring-shaped polarization electrodes; adjacent polarization electrodes are separated by an insulating layer.

[0009] 2) Preparation of periodic ferroelectric domain thin films:

[0010] A bottom electrode is deposited on the back side of the ferroelectric semiconductor thin film;

[0011] The ferroelectric semiconductor thin film is flipped onto the ferroelectric domain polarizer, that is, the front side of the ferroelectric semiconductor thin film faces down and is directly opposite the concentric ring-shaped polarization electrodes; the bottom electrode of the ferroelectric semiconductor thin film is connected to the ground wire; each polarization electrode is connected in parallel to an external power supply through polarization electrode leads;

[0012] An external power source applies amplitude-modulated alternating current to the surface of a ferroelectric semiconductor thin film through polarization electrodes. Under the action of the amplitude-modulated alternating current, the polarization of the ferroelectric semiconductor thin film reverses to a set depth on the front side. Multiple concentric ring-shaped narrow ferroelectric domains with alternating ferroelectric polarization directions are formed in the ferroelectric semiconductor thin film between two adjacent polarization electrodes, resulting in a periodic ferroelectric domain thin film. The width of the narrow ferroelectric domains is on the order of micrometers.

[0013] 3) Preparing the groove:

[0014] A circular groove is fabricated on the front side of a periodic ferroelectric domain thin film, and the depth of the circular groove is less than the depth at which the ferroelectric domains are formed.

[0015] Within a circular groove, a cylindrical groove is formed at the center of the circular groove, and an annular groove is formed at the edge of the circular groove. The cylindrical groove and the annular groove together constitute a reflective groove.

[0016] The retained portion forms a ring-shaped periodic ferroelectric domain thin film;

[0017] 4) Electrode preparation:

[0018] A filter output electrode and a filter input electrode are formed on a ring-shaped periodic ferroelectric domain thin film, respectively; the filter output electrode is a ring-shaped interdigitated electrode located on the inner side; multiple centrally symmetrical sheet-shaped filter input electrodes are formed between the filter output electrode and the ring groove of the reflector, and the width of the filter input electrode is on the order of centimeters.

[0019] 5) Sealed packaging:

[0020] The surface of the above structure is encapsulated using an encapsulation shell;

[0021] 6) Generate surface acoustic wave standing waves for filtering:

[0022] The radio frequency signal is input from the filter input electrode. The surface acoustic wave standing wave generated on the surface of the periodic ferroelectric domain thin film is used to filter the radio frequency signal. The filter output electrode is connected to an external circuit to transmit the filtered radio frequency signal.

[0023] In step 1), the polarization electrodes are made of metal, and the insulating layer is made of insulating material. Each polarization electrode has the same width, which is an integer multiple of the wavelength of the surface acoustic wave corresponding to the filter's operating frequency. This generates resonant amplification and enhancement of the surface acoustic wave, improving the energy conversion efficiency of the filter, reducing energy consumption, and thus improving the device's quality factor. The width of the insulating layer, i.e., the spacing between adjacent polarization electrodes, is the same for each insulating layer, ranging from 10 to 30 μm, and is an integer multiple of the width of the polarization electrode. The thickness of the polarization electrodes is 20 to 500 nm. The planar dimensions of the ferroelectric domain polarizer are circular with a diameter of 2 to 5 cm, consistent with the dimensions of a standard wafer.

[0024] In step 2), the thickness of the bottom electrode is 150~500nm, and the material is metal.

[0025] The frequency of the amplitude-modulated alternating current remains unchanged, but the peak voltage of the alternating current changes; the maximum value range of the peak voltage is 31~35V, the minimum value range is 0~10V, and the frequency is 10kHz~20kHz.

[0026] The peak voltage of the amplitude-modulated alternating current (AM) gradually decreases, creating a periodic electric field within the ferroelectric semiconductor thin film. The polarization reversal voltage of the ferroelectric semiconductor is a rated value. By gradually reducing the peak voltage of the AM AC, polarization reversal occurs on the front side of the ferroelectric semiconductor thin film to a predetermined depth, forming ferroelectric domains. Below the polarization electrode, the ferroelectric semiconductor thin film forms ring-shaped wide ferroelectric domains with the same width as the polarization electrode. The polarization directions of these concentric ring-shaped wide ferroelectric domains are consistent. Between adjacent polarization electrodes, the ferroelectric semiconductor thin film forms periodically alternating ring-shaped narrow ferroelectric domains with opposite polarization directions. These narrow ferroelectric domains are multiple concentric rings, with adjacent ring-shaped narrow ferroelectric domains having opposite polarization directions. The width of each narrow ferroelectric domain is half the wavelength of the surface acoustic wave corresponding to the filter's operating frequency. The thickness and width of the ring-shaped narrow ferroelectric domains with the same polarization direction are modulated by the applied AM AC voltage and frequency: the width of the narrow ferroelectric domain... ,in The threshold voltage constant of the ferroelectric semiconductor thin film material. For the frequency of amplitude-modulated alternating current, The rate of change of the peak voltage of amplitude-modulated alternating current; the depth of narrow ferroelectric domains. ,in and Iron

[0027] Threshold voltage constant and frequency response constant of electro-semiconductor thin film materials This is the maximum value of the peak voltage of the amplitude-modulated alternating current. The kinetic index is 1.7. The duration of voltage application for amplitude-modulated alternating current is related to both frequency and voltage. The thickness of the ferroelectric domains formed in the ferroelectric semiconductor thin film ranges from 100 nm to 300 nm. The higher the voltage, the deeper the ferroelectric domains are formed. The polarization reversal depth is directly related to the voltage of the amplitude-modulated alternating current (AM AC), and the polarization reversal width is directly related to the frequency of the AM AC. By setting the voltage and frequency of the AM AC, periodic ferroelectric domain films with a set period and width can be prepared on the ferroelectric semiconductor thin film. The width of these ferroelectric domains is not limited by the width of the polarization electrode but is controlled by the voltage and frequency of the AM AC, thus enabling the formation of periodic ferroelectric domains with linewidths on the nm scale.

[0028] In step 3), the depth of the circular groove is less than the depth of the ferroelectric domains. The depth of the circular groove is 30~80nm, and the thickness of the retained ferroelectric domains is 20~270nm. The depth of the reflective groove is 300~500nm, which is greater than that of the circular groove.

[0029] In step 4), the filter output electrode and filter input electrode are made of metal. Each filter input electrode is fan-shaped or partially fan-shaped, and each filter input electrode is centrally symmetrical and covers as much of the periodic ferroelectric domain film surface as possible. Multiple centrally symmetrical filter input electrodes are used instead of a single ring electrode to prevent excessive stress on the underlying ferroelectric domains, which could lead to breakage and damage to the periodic ferroelectric domain film. A gap of 500–2000 μm is left between adjacent filter input electrodes to reduce the stress on the semiconductor film during filter operation.

[0030] In step 5), the encapsulation shell is filled with inert gas; the encapsulation shell is made of alumina ceramic, epoxy resin or iron-nickel-cobalt alloy; the encapsulation shell has openings at corresponding positions of the filter output electrode and the filter input electrode to lead out the filter output electrode and multiple parallel filter input electrodes.

[0031] In step 6), traditional filter input electrodes use interdigitated electrodes formed on piezoelectric materials. An alternating RF voltage signal is input to the piezoelectric material, causing periodic vibrations that generate surface acoustic waves (SAWs), limiting the operating frequency. This invention uses a sheet-like filter input electrode formed on a periodic ferroelectric domain film. The characteristic width of the filter input electrode is 1-2 cm, while the characteristic width of the ferroelectric domains is 2 μm, a difference of 1000 times. The planar dimension of the sheet-like filter input electrode is much larger than the width of the annular narrow ferroelectric domains. The periodically alternating narrow ferroelectric domains with opposite polarization directions automatically generate opposite oscillations upon receiving in-phase voltage, forming a standing wave of SAW. The wavelength of the SAW is twice the width L of the ferroelectric domains. The filter's operating frequency... Similar to surface acoustic waves (SAWs), the operating frequency of the filter is determined by the width of the periodic narrow ferroelectric domains. Signals in the input RF signal that operate at the same frequency as the filter are amplified while other signals are suppressed, resulting in a filtered RF signal that operates at the same frequency as the filter. The operating frequency of the filter in this invention is consistent with SAWs due to the width of the periodic narrow ferroelectric domains. The fabrication process of these periodic narrow ferroelectric domains is much simpler than that of interdigitated electrodes. Furthermore, the higher the operating frequency, the narrower the width of the narrow ferroelectric domains. The width of the narrow ferroelectric domains is modulated by the voltage and frequency of the applied amplitude-modulated alternating current. Narrow ferroelectric domains with smaller widths are easier to fabricate, while the corresponding widths of traditional interdigitated electrodes are extremely difficult to fabricate. Therefore, the operating frequency of the filter in this invention is not limited and can operate at higher frequencies.

[0032] Another objective of this invention is to propose a surface acoustic wave filter based on periodic ferroelectric domains.

[0033] The surface acoustic wave filter based on periodic ferroelectric domains of the present invention includes: a bottom electrode, a periodic ferroelectric domain thin film, a reflective groove, a filter output electrode, a filter input electrode, and a package shell; wherein, the bottom electrode is deposited on the back side of the ferroelectric semiconductor thin film; multiple concentric ring-shaped narrow ferroelectric domains with alternating ferroelectric polarization directions are formed on the front side of the ferroelectric semiconductor thin film through a ferroelectric domain polarizer to obtain a periodic ferroelectric domain thin film; a circular groove is prepared on the front side of the periodic ferroelectric domain thin film, the depth of the circular groove being less than the depth of the ferroelectric domains; a cylindrical groove is formed at the center of the circular groove, and an annular groove is formed at the edge of the circular groove, together forming a... A reflective groove is formed, and the remaining portion forms a ring-shaped periodic ferroelectric domain film. A filter output electrode and a filter input electrode are formed on the ring-shaped periodic ferroelectric domain film, respectively. The filter output electrode is a ring-shaped interdigitated electrode located on the inner side. Multiple centrally symmetrical sheet-like filter input electrodes are formed between the filter output electrode and the ring groove of the reflective groove. The surface of the above structure is encapsulated using a packaging shell. A radio frequency (RF) signal is input from the filter input electrode, and a surface acoustic wave (SAW) standing wave is generated on the surface of the periodic ferroelectric domain film to filter the RF signal. The filter output electrode is connected to an external circuit to transmit the filtered RF signal.

[0034] Advantages of this invention:

[0035] This invention employs a ferroelectric domain polarizer to cause polarization reversal in a ferroelectric semiconductor thin film, forming multiple concentric ring-shaped narrow ferroelectric domains with alternating ferroelectric polarization directions, resulting in a periodic ferroelectric domain thin film. A sheet-like filter input electrode is formed on this periodic ferroelectric domain thin film. Upon receiving an in-phase voltage, the ferroelectric domains with opposite polarization directions automatically generate oscillations in opposite directions, forming surface acoustic wave standing waves. The filter's operating frequency is unrestricted and can operate at higher frequencies. This invention is applicable to fields such as radio frequency communication and 6G network transmission, high-precision radar, and remote sensing monitoring. Attached Figure Description

[0036] Figure 1 This is a top view of a ferroelectric domain polarizer, an embodiment of the surface acoustic wave filter based on periodic ferroelectric domains of the present invention.

[0037] Figure 2 A cross-sectional view of a periodic ferroelectric domain thin film fabricated for an embodiment of the surface acoustic wave filter based on periodic ferroelectric domains of the present invention.

[0038] Figure 3 This is a top view of a periodic ferroelectric domain thin film, representing an embodiment of the surface acoustic wave filter based on periodic ferroelectric domains of the present invention.

[0039] Figure 4 This is a flowchart illustrating the fabrication process of an embodiment of the surface acoustic wave filter based on periodic ferroelectric domains of the present invention, wherein (a) to (e) are cross-sectional views of each step.

[0040] Figure 5 This is a top view of the filter input and output electrodes of an embodiment of the surface acoustic wave filter based on periodic ferroelectric domains of the present invention.

[0041] Figure 6 This is a cross-sectional view of an embodiment of the surface acoustic wave filter based on periodic ferroelectric domains of the present invention.

[0042] Figure 7 This is a top view of an embodiment of the surface acoustic wave filter based on periodic ferroelectric domains of the present invention. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0044] In this embodiment, the operating frequency of the filter corresponds to a surface acoustic wave wavelength of 2μm, the operating frequency is 5GHz, and the sound velocity of the ferroelectric semiconductor thin film is 10000m / s.

[0045] The implementation method of the surface acoustic wave filter based on periodic ferroelectric domains in this embodiment includes the following steps:

[0046] 1) Fabrication of ferroelectric domain polarizers:

[0047] Concentric ring-shaped polarization electrode patterns were drawn on a ceramic insulating layer using photolithography, followed by the fabrication of gold polarization electrodes using vapor deposition. Adjacent polarization electrodes were separated by insulating layers of the same width, 60 μm. Figure 1 As shown, the plane in which the polarization electrodes are located is the XY plane. Each polarization electrode has the same width of 20μm and a thickness of 200nm. The material is a Ti / Al / Ni / Au multilayer alloy, and the diameter is 4 inches.

[0048] 2) Preparation of periodic ferroelectric domain thin films:

[0049] A 200nm thick gold or titanium bottom electrode is deposited on the back of a 4-inch diameter sapphire-based aluminum nitride ferroelectric semiconductor thin film, such as... Figure 4 As shown in (a);

[0050] A ferroelectric semiconductor thin film is inverted and placed on a ferroelectric domain polarizer, with the front side of the ferroelectric semiconductor thin film facing down and directly opposite the annular and concentric polarization electrodes; the bottom electrode of the ferroelectric semiconductor thin film is connected to ground; each polarization electrode is connected in parallel to an external power supply through polarization electrode leads, such as... Figure 2 As shown, the XZ plane is perpendicular to the plane containing the polarization electrode;

[0051] An external power source applies an amplitude-modulated alternating current (AM) to the surface of the ferroelectric semiconductor thin film through polarization electrodes. The maximum voltage is set to 30V and the frequency to 10kHz. Under the influence of the AM, polarization reversal occurs on the front side of the ferroelectric semiconductor thin film up to a depth of 200nm, resulting in a periodic ferroelectric domain thin film, such as... Figure 4 As shown in (b); the ferroelectric semiconductor thin film directly below the polarization electrode forms concentric ring-shaped wide ferroelectric domains with the same width as the polarization electrode. The polarization direction of each concentric ring-shaped wide ferroelectric domain directly below the polarization electrode is consistent. Between two adjacent polarization electrodes, the ferroelectric semiconductor thin film below forms periodically alternating concentric ring-shaped narrow ferroelectric domains with positive polarization and narrow ferroelectric domains with negative polarization. Narrow ferroelectric domains with the same ferroelectric polarization direction are multiple concentric rings, and the ferroelectric polarization directions of two adjacent ring-shaped narrow ferroelectric domains are opposite, such as... Figure 3 As shown, the plane in which the periodic ferroelectric domain film is located is the XY plane; the width of the narrow ferroelectric domain is 1 μm, which is half the wavelength of the surface acoustic wave corresponding to the operating frequency of the filter;

[0052] 3) Preparing the groove:

[0053] A 50 nm deep circular groove was fabricated on the front side of a periodic ferroelectric domain thin film;

[0054] Within a circular groove, a cylindrical groove is formed at the center, and an annular groove is formed at the edge of the circular groove. The cylindrical and annular grooves together constitute a reflective groove with a depth of 300 nm. Figure 4 As shown in (c);

[0055] The portion retained by the circular groove forms a ring-shaped periodic ferroelectric domain film with a thickness of 150 nm;

[0056] 4) Electrode preparation:

[0057] Filter output electrodes and filter input electrodes are formed on a ring-shaped periodic ferroelectric domain thin film. The filter output electrode is a ring-shaped interdigitated electrode located on the inner side, with a width of 0.5 μm, a thickness of 200 nm, and a spacing of 0.5 μm. Multiple centrally symmetrical, partially ring-shaped filter input electrodes are formed between the filter output electrode and the annular groove of the reflector. Each filter input electrode is centrally symmetrical and covers as much of the surface of the periodic ferroelectric domain thin film as possible, with a width of 3 cm and a thickness of 200 nm. Figure 4 As shown in (d); the top view of the filter output electrode and the filter input electrode is as shown in (d). Figure 5 As shown;

[0058] 5) Sealed packaging:

[0059] The surface of the above structure is encapsulated using a 4-inch diameter, 500μm thick alumina ceramic housing. Figure 4 As shown in (e); the package is filled with inert gas; the package has openings with a diameter of 20 μm and a depth of 500 μm at the corresponding positions of the filter output electrode and the filter input electrode, leading out the filter output electrode and connecting the filter input electrode; the cross-sectional view of the surface acoustic wave filter after packaging is shown in Figure 1. Figure 6 As shown, the top view is as follows Figure 7 As shown;

[0060] 6) Generate surface acoustic wave standing waves for filtering:

[0061] The radio frequency (RF) signal is input through the filter's input electrode. The planar dimension of the sheet-like filter input electrode is much larger than the width of the annular narrow ferroelectric domains. The periodically alternating narrow ferroelectric domains with opposite polarization directions automatically generate opposite oscillations upon receiving an in-phase voltage, forming a surface acoustic wave (SAW) standing wave. The wavelength of the SAW is twice the width L of the narrow ferroelectric domains. The filter's operating frequency is consistent with the SAW. Signals in the input RF signal that are consistent with the filter's operating frequency are amplified while other signals are suppressed, thus filtering the RF signal. The filtered RF signal is output, consistent with the filter's operating frequency. The filter's output electrode is connected to an external circuit to transmit the filtered RF signal. The filter of this invention has no limitation on its operating frequency and can operate at higher frequencies.

[0062] Finally, it should be noted that the purpose of disclosing the embodiments is to help further understand the present invention. However, those skilled in the art will understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the scope of protection of the present invention is defined by the claims.

Claims

1. A method for implementing a surface acoustic wave filter based on periodic ferroelectric domains, characterized in that, The implementation method includes the following steps: 1) Fabrication of ferroelectric domain polarizers: The ferroelectric domain polarizer comprises multiple concentric ring-shaped polarization electrodes; adjacent polarization electrodes are separated by an insulating layer. 2) Preparation of periodic ferroelectric domain thin films: A bottom electrode is deposited on the back side of the ferroelectric semiconductor thin film; A ferroelectric semiconductor thin film is flipped onto a ferroelectric domain polarizer; the bottom electrode of the ferroelectric semiconductor thin film is connected to ground, and each polarization electrode is connected in parallel to an external power supply; An external power source applies amplitude-modulated alternating current to the surface of a ferroelectric semiconductor thin film through polarization electrodes. The polarization of the front side of the ferroelectric semiconductor thin film is reversed, and multiple concentric ring-shaped narrow ferroelectric domains with alternating ferroelectric polarization directions are formed in the ferroelectric semiconductor thin film between adjacent polarization electrodes, resulting in a periodic ferroelectric domain thin film. 3) Preparing the groove: A circular groove is fabricated on the front side of a periodic ferroelectric domain thin film; a cylindrical groove is formed at the center of the circular groove, and an annular groove is formed at the edge, together forming a reflective groove; The retained portion forms a ring-shaped periodic ferroelectric domain thin film; 4) Electrode preparation: A filter output electrode and a filter input electrode are formed on a ring-shaped periodic ferroelectric domain thin film, respectively; the filter output electrode is located on the inner side; a plurality of centrally symmetrical sheet-shaped filter input electrodes are formed between the filter output electrode and the annular groove of the reflector. 5) Sealed packaging: The surface of the above structure is encapsulated using an encapsulation shell; 6) Generate surface acoustic wave standing waves for filtering: The radio frequency signal is input from the filter input electrode. The surface acoustic wave standing wave generated on the surface of the periodic ferroelectric domain thin film is used to filter the radio frequency signal. The filter output electrode is connected to an external circuit to transmit the filtered radio frequency signal.

2. The implementation method as described in claim 1, characterized in that, In step 1), the width of each polarization electrode is the same and is an integer multiple of the wavelength of the surface acoustic wave corresponding to the operating frequency of the filter; the width of each insulating layer is the same and is an integer multiple of the width of the polarization electrode.

3. The implementation method as described in claim 1, characterized in that, In step 2), the thickness of the bottom electrode is 150~500nm, and the material is metal.

4. The implementation method as described in claim 1, characterized in that, In step 2), the frequency of the amplitude-modulated alternating current is 10kHz~20kHz.

5. The implementation method as described in claim 1, characterized in that, In step 2), a ring-shaped wide ferroelectric domain with the same width as the polarizing electrode is formed on the ferroelectric semiconductor thin film directly below the polarizing electrode, and the polarization direction of each concentric ring-shaped wide ferroelectric domain is consistent; between adjacent wide ferroelectric domains are periodically alternating narrow ferroelectric domains with opposite polarization directions; the width of the narrow ferroelectric domain is half the wavelength of the surface acoustic wave corresponding to the operating frequency of the filter, and the thickness and width of the narrow ferroelectric domain are modulated by the voltage and frequency of the applied amplitude-modulated alternating current.

6. The implementation method as described in claim 1, characterized in that, In step 3), the depth of the circular groove is 30~80nm; the depth of the reflective groove is 300~500nm.

7. A surface acoustic wave filter based on periodic ferroelectric domains, characterized in that, The surface acoustic wave filter, manufactured using the method described in any one of claims 1 to 6, comprises: a bottom electrode, a periodic ferroelectric domain thin film, a reflective groove, a filter output electrode, a filter input electrode, and a package housing; wherein, the bottom electrode is deposited on the back side of the ferroelectric semiconductor thin film; multiple concentric ring-shaped narrow ferroelectric domains with alternating ferroelectric polarization directions are formed on the front side of the ferroelectric semiconductor thin film using a ferroelectric domain polarizer to obtain a periodic ferroelectric domain thin film; a circular groove is prepared on the front side of the periodic ferroelectric domain thin film; a cylindrical groove is formed at the center of the circular groove, and an annular groove is formed at the edge of the circular groove, together... A reflective groove is formed, and the remaining portion forms a ring-shaped periodic ferroelectric domain film. A filter output electrode and a filter input electrode are formed on the ring-shaped periodic ferroelectric domain film, with the filter output electrode located on the inner side. Multiple centrally symmetrical sheet-like filter input electrodes are formed between the filter output electrode and the ring-shaped groove of the reflective groove. The surface of the above structure is encapsulated using a packaging shell. A radio frequency (RF) signal is input from the filter input electrode, and a surface acoustic wave (SAW) standing wave is generated on the surface of the periodic ferroelectric domain film to filter the RF signal. The filter output electrode is connected to an external circuit to transmit the filtered RF signal.

8. The surface acoustic wave filter as described in claim 7, characterized in that, Each polarization electrode has the same width, which is an integer multiple of the surface acoustic wave wavelength corresponding to the operating frequency of the filter; each insulating layer has the same width, which is an integer multiple of the width of the polarization electrode.

9. The surface acoustic wave filter as described in claim 7, characterized in that, The thickness of the ferroelectric semiconductor thin film forming ferroelectric domains is 100nm~300nm.

10. The surface acoustic wave filter as described in claim 7, characterized in that, The depth of the circular groove is 30~80nm; the depth of the reflective groove is 300~500nm.

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