Bulk acoustic wave resonance apparatus and forming method therefor, and filtering apparatus

Abstract

A bulk acoustic wave resonance apparatus and a forming method therefor, and a filtering apparatus. The resonance apparatus comprises: an acoustic reflection layer; a first electrode layer, which comprises a first resonance portion, a first attenuation portion and a first limiting portion; a piezoelectric layer, which comprises a first side and a second side, wherein the first electrode layer is located on the first side; a second electrode layer, which is located on the second side, and comprises a second resonance portion; a first dielectric layer, which is located on the first side; a first load layer, which is located on the first side; a first attenuation region, which comprises the first attenuation portion and a first dielectric portion; and a first limiting region, which comprises the first limiting portion, a second dielectric portion and the first load layer. By means of rationally setting the width of a first attenuation region, high-order transverse parasitic modes can be fully attenuated in a first attenuation region, and only a small number or even no higher-order transverse parasitic modes enter a first limiting region, such that the situation where the high-order transverse parasitic modes are reflected back to a resonance region and are coupled to a transverse master mode is prevented, and thus a parallel impedance value and a corresponding Q value can be increased.

Description

Bulk acoustic wave resonator device, forming method thereof, and filtering device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on February 9, 2024, with application number 202410178605.3 and invention name “Bulk Acoustic Wave Resonator Device, Formation Method Thereof, and Filtering Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to the field of semiconductor technology, and in particular to a bulk acoustic wave resonator device, a forming method thereof, and a filtering device. Background Art

[0003] The radio frequency (RF) front-end chips for wireless communication devices include power amplifiers, antenna switches, RF filters, multiplexers including duplexers, and low-noise amplifiers. RF filters include surface acoustic wave (SAW) filters, bulk acoustic wave (BAW) filters, micro-electro-mechanical system (MEMS) filters, and integrated passive device (IPD) filters.

[0004] BAW resonators have a high quality factor (Q value). RF filters made from BAW resonators offer low insertion loss and high out-of-band rejection, making them one of the mainstream RF filters used in wireless communication devices such as mobile phones and base stations. The Q value is the resonator's quality factor, defined as the center frequency divided by the resonator's 3dB bandwidth. BAW filters typically operate in the 0.7GHz to 7GHz range.

[0005] As wireless communication technology evolves, more and more frequency bands are being used. Simultaneously, with the application of frequency-band overlapping technologies like carrier aggregation, mutual interference between wireless frequency bands has become increasingly severe. High-performance bulk acoustic wave (BAW) technology can address this inter-band interference problem. With the advent of 5G, wireless mobile networks are introducing higher frequency bands. Currently, only BAW technology can address the filtering issues in these high-frequency bands.

[0006] However, BAW resonator devices still have many problems. Summary of the Invention

[0007] The technical problem solved by the present invention is to provide a bulk acoustic wave resonator device and a forming method thereof, and a filtering device, so as to further improve the Q of the acoustic wave resonator device.

[0008] In order to solve the above problems, the technical solution of the present invention provides a bulk acoustic wave resonance device, comprising: an acoustic reflection layer; a first electrode layer, the first electrode layer comprising a first resonance part, a first attenuation part located outside the first resonance part, the first attenuation part surrounding the first resonance part, and a first restriction part located outside the first attenuation part, the first restriction part surrounding the first attenuation part; a piezoelectric layer, the piezoelectric layer comprising a first side and a second side opposite to the first side, the first electrode layer being located on the first side, the acoustic reflection layer being located on the first side or the second side; a second electrode layer, the second electrode layer being located on the second side, the second electrode layer corresponding to the first electrode layer, the second electrode layer comprising a second resonance part, the second resonance part corresponding to the first resonance part; a resonance region, the resonance region comprising the first resonance part, the second resonance part, and a second resonance part located on the first side. The piezoelectric layer between the resonating part and the second resonating part; a first dielectric layer, the first dielectric layer is located on the first side, the first dielectric layer includes a first dielectric part and a second dielectric part, the first dielectric part is located between part of the first attenuation part and the piezoelectric layer, and the second dielectric part is located between the first limiting part and the piezoelectric layer; a first load layer, the first load layer is located on the first side, the first load layer corresponds to the first limiting part and the second dielectric part; a first attenuation zone located outside the resonating zone, suitable for attenuating sound waves, the first attenuation zone surrounds the resonating zone, the first attenuation zone includes the first attenuation part and the first dielectric part; a first limiting zone located outside the first attenuation zone, suitable for reflecting sound waves, the first limiting zone surrounds the first attenuation zone, the first limiting zone includes the first limiting part, the second dielectric part and the first load layer.

[0009] Optionally, the first attenuation section includes a first sub-section and a second sub-section, the second sub-section is located outside the first sub-section; the angle between the first sub-section and the first resonant section is greater than or equal to 90° and less than 180°; the angle between the first sub-section and the second sub-section is greater than or equal to 90° and less than 180°.

[0010] Optionally, the first dielectric portion is located between the second sub-portion and the piezoelectric layer; and the first dielectric portion is located outside the first sub-portion.

[0011] Optionally, the first dielectric portion is also located between part of the first sub-portion and the piezoelectric layer.

[0012] Optionally, the thickness range of the first dielectric layer includes: 0.1t to 2t, where t represents the thickness of the first electrode layer; the width range of the first dielectric part includes: 0.2s to 6s, where s represents the thickness of the resonant region stacked structure.

[0013] Optionally, the thickness range of the first load layer includes: 0.1t to 3t, where t represents the thickness of the first electrode layer; the width range of the first load layer includes: 0.2s to 6s, where s represents the thickness of the resonant region stacked structure.

[0014] Optionally, the material density of the first support layer is greater than or equal to the material density of the first electrode layer.

[0015] Optionally, the first load-bearing layer is located between the second medium portion and the first limiting portion.

[0016] Optionally, the first limiting portion is located between the second dielectric portion and the first load-bearing layer.

[0017] Optionally, the distance between the outer edge of the first electrode layer and the outer edge of the first load layer ranges from -2s to 2s, where s represents the thickness of the resonant region stacked structure.

[0018] Optionally, the first electrode layer further includes a second attenuation portion located outside the first limiting portion, and the second attenuation portion surrounds the first limiting portion; the first dielectric layer further includes a third dielectric portion, and the third dielectric portion is located between the piezoelectric layer and the second attenuation portion.

[0019] Optionally, it further includes: a second attenuation zone located outside the first restriction zone, suitable for attenuating sound waves, the second attenuation zone surrounds the first restriction zone, and the second attenuation zone includes a second attenuation portion and the third dielectric portion.

[0020] Optionally, the sound reflection layer includes: a cavity or a Bragg reflection layer.

[0021] Optionally, the acoustic reflection layer is a Bragg reflection layer, the Bragg reflection layer is located on the second side, the second electrode layer is located between the Bragg reflection layer and the piezoelectric layer, the second electrode layer also includes a first non-resonant portion, the first non-resonant portion is located outside the second resonant portion and surrounds the second resonant portion, the first non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes the first non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the first non-resonant portion corresponding to the first limiting portion.

[0022] Optionally, the sound reflecting layer is a cavity, the cavity is located on the second side, the second electrode layer is located between the cavity and the piezoelectric layer and covers the cavity, the second electrode layer also includes a second non-resonant portion, the second non-resonant portion is located outside the second resonant portion and surrounds the second resonant portion, the second non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes the second non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the second non-resonant portion corresponding to the first limiting portion.

[0023] Optionally, the sound reflection layer is a cavity, the cavity is located on the second side, the second electrode layer is located between the cavity and the piezoelectric layer, the second electrode layer is located in the cavity, the second electrode layer also includes a third non-resonant portion, the third non-resonant portion is located outside the second resonant portion and surrounds the second resonant portion, the third non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes the third non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the third non-resonant portion corresponding to the first limiting portion.

[0024] Optionally, the sound reflection layer is a cavity, the cavity is located on the first side, the first electrode layer, the first dielectric layer and the first load layer are located between the cavity and the piezoelectric layer, and the first electrode layer, the first dielectric layer and the first load layer are located in the cavity.

[0025] Optionally, the second electrode layer also includes a fourth non-resonant portion, which is located outside the second resonant portion and surrounds the second resonant portion, and the fourth non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes the fourth non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the fourth non-resonant portion corresponding to the first limiting portion.

[0026] Optionally, the second electrode layer further includes a third attenuation portion located outside the second resonating portion, the third attenuation portion surrounding the second resonating portion, and a second limiting portion located outside the third attenuating portion, the second limiting portion surrounding the third attenuating portion.

[0027] Optionally, it also includes: a second dielectric layer, the second dielectric layer is located on the second side, the second dielectric layer includes a fourth dielectric portion and a fifth dielectric portion, the fourth dielectric portion is located between part of the third attenuation portion and the piezoelectric layer, and the fifth dielectric portion is located between the second limiting portion and the piezoelectric layer; a second load layer, the second load layer is located on the second side, and the second load layer corresponds to the second limiting portion and the fifth dielectric portion.

[0028] Optionally, the first attenuation zone further includes a third attenuation portion and the fourth dielectric portion; the first restriction zone further includes a second restriction portion, the fifth dielectric portion and the second load layer.

[0029] Correspondingly, the technical solution of the present invention also provides a method for forming a bulk acoustic wave resonator device, including: forming an acoustic reflection layer; forming a first electrode layer, the first electrode layer including a first resonant part, a first attenuation part located outside the first resonant part, the first attenuation part surrounding the first resonant part, and a first limiting part located outside the first attenuation part, the first limiting part surrounding the first attenuation part; forming a piezoelectric layer, the piezoelectric layer including a first side and a second side opposite to the first side, the first electrode layer is formed on the first side, and the acoustic reflection layer is formed on the first side or the second side; forming a second electrode layer located on the second side, the second electrode layer corresponding to the first electrode layer, the second electrode layer including a second resonant part, the second resonant part corresponding to the first resonant part; forming a resonance zone, the resonance zone including the first resonant part, the second resonant part, and the piezoelectric layer formed between the first resonating part and the second resonating part; forming a first dielectric layer, located on the first side, the first dielectric layer including a first dielectric part and a second dielectric part, the first dielectric part being located between part of the first attenuation part and the piezoelectric layer, and the second dielectric part being located between the first limiting part and the piezoelectric layer; forming a first load layer, located on the first side, the first load layer corresponding to the first limiting part and the second dielectric part; forming a first attenuation zone outside the resonance zone, suitable for attenuating sound waves, the first attenuation zone surrounding the resonance zone, the first attenuation zone including the first attenuation part and the first dielectric part; forming a first limiting zone outside the first attenuation zone, suitable for reflecting sound waves, the first limiting zone surrounding the first attenuation zone, the first limiting zone including the first limiting part, the second dielectric part and the first load layer.

[0030] Optionally, the first attenuation section includes a first sub-section and a second sub-section, the second sub-section is located outside the first sub-section; the angle between the first sub-section and the first resonant section is greater than or equal to 90° and less than 180°; the angle between the first sub-section and the second sub-section is greater than or equal to 90° and less than 180°.

[0031] Optionally, the first dielectric portion is located between the second sub-portion and the piezoelectric layer; and the first dielectric portion is located outside the first sub-portion.

[0032] Optionally, the first dielectric portion is also located between part of the first sub-portion and the piezoelectric layer.

[0033] Optionally, the first load-bearing layer is formed between the second dielectric portion and the first limiting portion.

[0034] Optionally, after forming the first electrode layer, the first load layer is formed, and the first limiting portion is located between the second dielectric portion and the first load layer.

[0035] Optionally, the first electrode layer further includes a second attenuation portion located outside the first limiting portion, and the second attenuation portion surrounds the first limiting portion; the first dielectric layer further includes a third dielectric portion, and the third dielectric portion is located between the piezoelectric layer and the second attenuation portion.

[0036] Optionally, it further includes: a second attenuation zone formed outside the first restriction zone, suitable for attenuating sound waves, the second attenuation zone surrounds the first restriction zone, and the second attenuation zone includes a second attenuation portion and the third dielectric portion.

[0037] Optionally, forming the sound reflection layer includes forming a cavity or forming a Bragg reflection layer.

[0038] Optionally, the Bragg reflection layer is formed on the second side, the second electrode layer is formed between the Bragg reflection layer and the piezoelectric layer, the second electrode layer also includes a first non-resonant portion, the first non-resonant portion is located outside the second resonant portion and surrounds the second resonant portion, the first non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes the first non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the first non-resonant portion corresponding to the first limiting portion.

[0039] Optionally, the cavity is formed on the second side, the second electrode layer is formed between the cavity and the piezoelectric layer and covers the cavity, the second electrode layer also includes a second non-resonant portion, the second non-resonant portion is located outside the second resonant portion and surrounds the second resonant portion, the second non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes the second non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the second non-resonant portion corresponding to the first limiting portion.

[0040] Optionally, the cavity is formed on the second side, the second electrode layer is formed between the cavity and the piezoelectric layer, the second electrode layer is formed in the cavity, the second electrode layer also includes a third non-resonant portion, the third non-resonant portion is located outside the second resonant portion and surrounds the second resonant portion, the third non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes the third non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the third non-resonant portion corresponding to the first limiting portion.

[0041] Optionally, the cavity is formed on the first side, the first electrode layer, the first dielectric layer and the first load layer are formed between the cavity and the piezoelectric layer, and the first electrode layer, the first dielectric layer and the first load layer are formed in the cavity.

[0042] Optionally, the second electrode layer also includes a fourth non-resonant portion, which is located outside the second resonant portion and surrounds the second resonant portion, and the fourth non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes a fourth non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the fourth non-resonant portion corresponding to the first limiting portion.

[0043] Optionally, the second electrode layer further includes a third attenuation portion located outside the second resonating portion, the third attenuation portion surrounding the second resonating portion, and a second limiting portion located outside the third attenuating portion, the second limiting portion surrounding the third attenuating portion.

[0044] Optionally, it also includes: forming a second dielectric layer located on the second side, the second dielectric layer including a fourth dielectric portion and a fifth dielectric portion, the fourth dielectric portion being located between part of the third attenuation portion and the piezoelectric layer, and the fifth dielectric portion being located between the second limiting portion and the piezoelectric layer; forming a second load layer located on the second side, the second load layer corresponding to the second limiting portion and the fifth dielectric portion.

[0045] Optionally, the first attenuation zone further includes a third attenuation portion and the fourth dielectric portion; the first restriction zone further includes a second restriction portion, the fifth dielectric portion and the second load layer.

[0046] Correspondingly, the technical solution of the present invention further provides a filtering device, characterized in that it includes the bulk acoustic wave resonator device as described in any of the above technical solutions.

[0047] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0048] In the bulk acoustic wave resonator device of the technical solution of the present invention, the first dielectric layer is located between the first attenuation portion, the first limiting portion and the piezoelectric layer. Therefore, the first attenuation region and the first limiting region corresponding to the first dielectric layer do not undergo acoustic-to-electrical conversion, and thus do not excite additional parasitic resonances. Since the cutoff frequency of the first attenuation region matches (for example, is equal to or less than) the cutoff frequency of the resonance region, and the acoustic impedance of the first limiting region is mismatched with the acoustic impedance of the first attenuation region, that is, the impedance difference is large, the main transverse mode can first pass through the first attenuation region without being affected, and then be fully reflected back to the resonance region in the first limiting region, thereby significantly reducing transverse leakage waves; however, high-order transverse parasitic modes entering the first attenuation region will experience attenuation. By reasonably setting the width of the first attenuation region, the high-order transverse parasitic modes can be fully attenuated in the first attenuation region, and only a small amount or even no high-order transverse parasitic modes enter the first limiting region, thereby preventing the high-order transverse parasitic modes from reflecting back to the resonance region and coupling with the main transverse mode, thereby improving the parallel impedance value and the corresponding Q value.

[0049] In the method for forming a bulk acoustic wave resonator device according to the technical solution of the present invention, the first dielectric layer is located between the first attenuation portion, the first limiting portion, and the piezoelectric layer. Therefore, the first attenuation region and the first limiting region corresponding to the first dielectric layer do not undergo acoustic-to-electrical conversion, and thus do not excite additional parasitic resonances. Since the cutoff frequency of the first attenuation region matches (e.g., is equal to or less than) the cutoff frequency of the resonance region, and the acoustic impedance of the first limiting region is mismatched with the acoustic impedance of the first attenuation region, that is, the impedance difference is large, the main transverse mode can first pass through the first attenuation region without being affected, and then be fully reflected back to the resonance region in the first limiting region, thereby significantly reducing transverse leakage waves; however, high-order transverse parasitic modes entering the first attenuation region will experience attenuation. By reasonably setting the width of the first attenuation region, the high-order transverse parasitic modes can be fully attenuated in the first attenuation region, with only a small amount or even no high-order transverse parasitic modes entering the first limiting region, thereby preventing the high-order transverse parasitic modes from reflecting back to the resonance region and coupling with the main transverse mode, thereby improving the parallel impedance value and the corresponding Q value. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG1 is a schematic structural diagram of a bulk acoustic wave resonance device;

[0051] 2 to 8 are schematic structural diagrams of various steps of a method for forming a bulk acoustic wave resonator device according to an embodiment of the present invention;

[0052] 9 is a schematic structural diagram of a bulk acoustic wave resonator device in another embodiment of the present invention;

[0053] 10 is a schematic structural diagram of a bulk acoustic wave resonator device according to another embodiment of the present invention;

[0054] 11 is a schematic structural diagram of a bulk acoustic wave resonator device according to another embodiment of the present invention;

[0055] 12 is a schematic structural diagram of a bulk acoustic wave resonator device in another embodiment of the present invention;

[0056] 13 to 26 are schematic structural diagrams of various steps of a method for forming a bulk acoustic wave resonator device according to another embodiment of the present invention;

[0057] FIG27 is a schematic structural diagram of a bulk acoustic wave resonator device according to another embodiment of the present invention;

[0058] 28 to 41 are schematic structural diagrams of various steps of a method for forming a bulk acoustic wave resonator device according to another embodiment of the present invention;

[0059] FIG42 is a schematic structural diagram of a bulk acoustic wave resonator device according to another embodiment of the present invention;

[0060] FIG43 is a schematic structural diagram of the steps of a method for forming a bulk acoustic wave resonator device according to another embodiment of the present invention;

[0061] FIG44 is a comparison diagram of the real part amplitude of impedance and the quality factor varying with frequency between the present invention and the prior art. DETAILED DESCRIPTION

[0062] As described in the background art, BAW resonator devices still have many problems, which will be described in detail below with reference to the accompanying drawings.

[0063] FIG1 is a schematic structural diagram of a bulk acoustic wave resonance device.

[0064] Please refer to Figure 1. A bulk acoustic wave resonator device includes: a substrate 100, wherein the substrate 100 has a cavity 101, and the surface of the substrate 100 exposes the cavity 101; a lower electrode layer 102 located on the substrate 100, covering the cavity 101; a piezoelectric layer 103 located on the lower electrode layer 102; an upper electrode layer 104 located on the piezoelectric layer 103, wherein the projections of the upper electrode layer 104 and the lower electrode layer 102 toward the substrate 100 have an overlapping area, and the overlapping area constitutes a resonance area; a raised edge structure 105 located on the piezoelectric layer 103, wherein the raised edge structure 105 surrounds the upper electrode layer 104; a reflection area, located laterally outside the resonance area and surrounding the resonance area, wherein the reflection area includes the raised edge structure 105, and the acoustic impedance of the reflection area is out of sync with the acoustic impedance of the resonance area, that is, the acoustic impedance difference is large.

[0065] There are two main factors that reduce the quality factor at the parallel resonance point of a bulk acoustic wave resonator: (1) the acoustic wave propagates laterally from the resonance region to areas outside the resonance region, causing acoustic energy leakage; and (2) the coupling of high-order transverse parasitic modes with the transverse main mode.

[0066] In the above-described embodiment, the formation of the reflective region laterally outside the resonant region by the raised edge structure 105 can suppress the effects of the first factor, reflecting the first-order transverse mode (the main mode) back into the resonant region, thereby preventing the leakage of most acoustic energy. However, this does not alleviate the second factor. Furthermore, reflecting the first-order transverse mode also reflects higher-order transverse parasitic modes, increasing their coupling with the main mode and preventing further improvement in the Q of the BAW resonator.

[0067] On this basis, the present invention provides a bulk acoustic wave resonator device, a method for forming the same, and a filtering device. The first dielectric layer is located between the first attenuation portion, the first limiting portion, and the piezoelectric layer. Therefore, the first attenuation region and the first limiting region corresponding to the first dielectric layer do not undergo acoustic-to-electrical conversion, thereby not exciting additional parasitic resonances. Because the cutoff frequency of the first attenuation region matches (e.g., is equal to or less than) the cutoff frequency of the resonance region, while the acoustic impedance of the first limiting region is mismatched with the acoustic impedance of the first attenuation region, i.e., the impedance difference is large, the main transverse mode can first pass through the first attenuation region unaffected and then be fully reflected back to the resonance region in the first limiting region, thereby significantly reducing transverse leakage waves. However, high-order transverse parasitic modes that enter the first attenuation region will experience attenuation. By properly setting the width of the first attenuation region, the high-order transverse parasitic modes can be fully attenuated within the first attenuation region, with only a small amount or even no high-order transverse parasitic modes entering the first limiting region. This prevents the high-order transverse parasitic modes from reflecting back to the resonance region and coupling with the main transverse mode, thereby improving the parallel impedance value and the corresponding Q value.

[0068] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0069] 2 to 8 are schematic structural diagrams of various steps of a method for forming a bulk acoustic wave resonator according to an embodiment of the present invention; FIG. 9 is a schematic structural diagram of a bulk acoustic wave resonator according to another embodiment of the present invention.

[0070] Please refer to FIG. 2 , where a sound reflecting layer is formed.

[0071] In this embodiment, forming the sound reflection layer includes forming a cavity 201 .

[0072] In this embodiment, forming the sound reflection layer further includes: providing a substrate 200 , the cavity 201 being formed in the substrate 200 , and the cavity 201 being exposed on a surface of the substrate 200 .

[0073] Referring to FIG. 3 , a sacrificial layer 202 is formed in the cavity 201 .

[0074] The sacrificial layer 202 provides temporary support for the device structure subsequently formed on the substrate 200 . After the device structure on the substrate 200 is formed, the sacrificial layer 202 needs to be removed.

[0075] The method for forming the sacrificial layer 202 includes: forming the initial sacrificial layer (not shown) in the cavity 201 and on the surface of the substrate 200 ; and planarizing the initial sacrificial layer until the surface of the substrate 200 is exposed, thereby forming the sacrificial layer 202 .

[0076] Referring to FIG. 4 , a second electrode layer 203 is formed. The second electrode layer 203 includes a second resonant portion 203 a.

[0077] In this embodiment, the second electrode layer 203 further includes a second non-resonant portion 203 b , which is located outside the second resonant portion 203 a (ie, on one side of the transverse periphery) and surrounds the second resonant portion 203 a .

[0078] In this embodiment, the second electrode layer 203 is located on the substrate 200 .

[0079] In this embodiment, both ends of the second electrode layer 203 are located outside the sacrificial layer 202 , that is, the second electrode layer 203 covers the sacrificial layer 202 .

[0080] It should be noted that the material of the second electrode layer 203 includes: molybdenum, tungsten, copper, platinum, rhenium, osmium, iridium, tantalum, gold or hafnium.

[0081] In this embodiment, the second electrode layer 203 is made of molybdenum.

[0082] 5 , a piezoelectric layer 204 is formed. The piezoelectric layer 204 includes a first side 2041 and a second side 2042 opposite to the first side 2041 . The acoustic reflection layer is formed on the second side 2042 .

[0083] In this embodiment, the second electrode layer 203 is located on the second side 2042, the piezoelectric layer 204 is located on the second electrode layer 203 and in contact with the second electrode layer 203, and the second electrode layer 203 is formed between the sacrificial layer 202 and the piezoelectric layer 204 and covers the sacrificial layer 202, that is, the second electrode layer 203 is the lower electrode layer of the bulk acoustic wave resonator device.

[0084] It should be noted that the material of the piezoelectric layer 204 includes: lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate, aluminum nitride, aluminum nitride alloy, gallium nitride or zinc oxide.

[0085] In this embodiment, the material of the piezoelectric layer 204 is aluminum nitride or aluminum nitride alloy.

[0086] Referring to FIG. 6 , a first dielectric layer 205 is formed and located on the first side 2041 . The first dielectric layer 205 includes a first dielectric portion 205 a and a second dielectric portion 205 b .

[0087] It should be noted that the material of the first dielectric layer 205 includes: silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride or air.

[0088] In this embodiment, the material of the first dielectric layer 205 is silicon oxide.

[0089] In this embodiment, the first dielectric layer 205 is formed on the piezoelectric layer 204 and contacts the piezoelectric layer 204 .

[0090] The method for forming the first dielectric layer 205 includes: forming a first dielectric material layer (not shown) on the piezoelectric layer 204 ; and patterning the first dielectric material layer to form the first dielectric layer 205 .

[0091] 7 , a first load layer 206 is formed and located on the first side 2041 . The first load layer 206 corresponds to the second dielectric portion 205 b .

[0092] In this embodiment, the first load layer 206 is located on the second dielectric portion 205 b and is in contact with the second dielectric portion 205 b.

[0093] It should be noted that the material of the first load layer 206 includes: molybdenum, tungsten, platinum, palladium, gold, chromium, tantalum or iridium.

[0094] Please refer to Figure 8, a first electrode layer 207 is formed, which includes a first resonant portion 207a, a first attenuation portion 207b located outside the first resonant portion 207a, the first attenuation portion 207b surrounding the first resonant portion 207a, and a first limiting portion 207c located outside the first attenuation portion 207b, the first limiting portion 207c surrounding the first attenuation portion 207b.

[0095] In this embodiment, the first electrode layer 207 is formed on the first side 2041 , and the first resonant portion 207 a contacts the piezoelectric layer 204 . That is, the first electrode layer 207 is the upper electrode layer of the BAW resonator.

[0096] In this embodiment, the second electrode layer 203 corresponds to the first electrode layer 207 , and the second resonant portion 203 a corresponds to the first resonant portion 207 a .

[0097] In this embodiment, the first dielectric portion 205a is located between a portion of the first attenuation portion 207b and the piezoelectric layer 204, and the second dielectric portion 205b is located between the first limiting portion 207c and the piezoelectric layer 204. In this embodiment, the first load layer 206 corresponds to the first limiting portion 207c. Specifically, the first load layer 206 is formed between the second dielectric portion 205b and the first limiting portion 207c. It should be noted that the first attenuation portion 207b includes a first sub-portion 207b1 and a second sub-portion 207b2, with the second sub-portion 207b2 located outside the first sub-portion 207b1. The angle between the first sub-portion 207b1 and the first resonant portion 207a is greater than or equal to 90° and less than 180°. The angle between the first sub-portion 207b1 and the second sub-portion 207b2 is greater than or equal to 90° and less than 180°.

[0098] 8 , in this embodiment, the angle between the first sub-portion 207b1 and the first resonant portion 207a is equal to 90°, and the angle between the first sub-portion 207b1 and the second sub-portion 207b2 is equal to 90°.

[0099] In this embodiment, the first dielectric portion 205 a is located between the second sub-portion 207 b 2 and the piezoelectric layer 204 ; the first dielectric portion 205 a is located outside the first sub-portion 207 b 1 .

[0100] Please refer to Figure 9. In other embodiments, the angle between the first sub-section 207b1 and the first resonant section 207a is greater than 90° and less than 180°, and the angle between the first sub-section 207b1 and the second sub-section 207b2 is greater than 90° and less than 180°; the first dielectric section 205a is also located between part of the first sub-section 207b1 and the piezoelectric layer 204.

[0101] In this embodiment, the method further includes forming a resonance region 208 , wherein the resonance region 208 includes the first resonance portion 207 a , the second resonance portion 203 a , and the piezoelectric layer 204 formed between the first resonance portion 207 a and the second resonance portion 203 a .

[0102] In this embodiment, the second non-resonant portion 203 b corresponds to the first attenuation portion 207 b and the first limiting portion 207 c.

[0103] In this embodiment, the present invention further includes: a first attenuation zone 209 formed outside the resonance zone 208, suitable for attenuating sound waves, the first attenuation zone 209 surrounds the resonance zone 208, and the first attenuation zone 209 includes a first attenuation portion 207b, the first dielectric portion 205a, and the second non-resonant portion 203b corresponding to the first attenuation portion 207b; a first restriction zone 210 formed outside the first attenuation zone 209, suitable for reflecting sound waves, the first restriction zone 210 surrounds the first attenuation zone 209, and the first restriction zone 210 includes a first restriction portion 207c, the second dielectric portion 205b, the first load layer 206, and the second non-resonant portion 203b corresponding to the first restriction portion 207c.

[0104] It should be noted that the thickness range of the first dielectric layer 205 includes: 0.1t to 2t, where t represents the thickness of the first electrode layer 207; the width range of the first dielectric portion 205a includes: 0.2s to 6s, where s represents the thickness of the stacked structure of the resonance zone 208 (for example, the sum of the thicknesses of the first resonance portion 207a, the second resonance portion 203a and the piezoelectric layer 204).

[0105] It should be noted that the thickness range of the first load layer 206 includes: 0.1t to 3t, where t represents the thickness of the first electrode layer 207; the width range of the first load layer 206 includes: 0.2s to 6s, where s represents the thickness of the stacked structure of the resonance zone 208.

[0106] In this embodiment, the material density of the first load layer 206 is greater than or equal to the material density of the first electrode layer 207, so as to increase the overall mass of the first restriction zone 210, thereby increasing the difference between the acoustic impedance of the first restriction zone 210 and the acoustic impedance of the resonance zone 208, thereby forming an acoustic impedance mismatch.

[0107] It should be noted that the spacing between the outer edge of the first electrode layer 207 and the outer edge of the first load layer 206 ranges from -2s to 2s, where s represents the thickness of the stacked structure of the resonant region 208. A negative spacing value indicates that the outer edge of the first electrode layer 207 is located inside the outer edge of the first load layer 206 (i.e., the first load layer 206 is not covered by the first electrode layer 207); a positive spacing value indicates that the outer edge of the first electrode layer 207 is located outside the outer edge of the first load layer 206 (i.e., the first load layer 206 is covered by the first electrode layer 207). In this embodiment, the spacing between the outer edges of the first electrode layer 207 and the outer edges of the first load layer 206 is 0 (i.e., they are flush).

[0108] The first dielectric layer 205 is located between the first attenuation portion 207b, the first limiting portion 207c and the piezoelectric layer 204. Therefore, the first attenuation area 209 and the first limiting area 210 corresponding to the first dielectric layer 205 do not undergo acoustic-to-electrical conversion, and thus do not excite additional parasitic resonances. Since the cutoff frequency of the first attenuation zone 209 matches (for example, is equal to or less than) the cutoff frequency of the resonance zone 208, and the acoustic impedance of the first restriction zone 210 is mismatched with the acoustic impedance of the first attenuation zone 209, that is, the impedance difference is relatively large, the main transverse mode can first pass through the first attenuation zone 209 without being affected, and then be fully reflected back to the resonance zone in the first restriction zone 210, thereby significantly reducing the transverse leakage wave; however, the high-order transverse parasitic modes entering the first attenuation zone 209 will experience attenuation. By reasonably setting the width of the first attenuation zone 209, the high-order transverse parasitic modes can be fully attenuated in the first attenuation zone 209, and only a small amount or even no high-order transverse parasitic modes can enter the first restriction zone 210, thereby preventing the high-order transverse parasitic modes from being reflected back to the resonance zone 208 and coupling with the main transverse mode, thereby improving the parallel impedance value and the corresponding Q value.

[0109] Please refer to Figure 44, in which the horizontal axis is frequency, the vertical axis on the left is the amplitude of the real part of impedance, and the vertical axis on the right is the quality factor (BodeQ) that changes with frequency. The solid line with triangle symbols in the figure represents the amplitude of the real part of impedance of the bulk acoustic wave resonator in the present invention, and the dotted line with triangle symbols represents the amplitude of the real part of impedance of the bulk acoustic wave resonator in the prior art. The frequency corresponding to the highest point represents the parallel resonant frequency of the resonator. The solid line in the figure represents the BodeQ curve of the bulk acoustic wave resonator in the present invention, and the dotted line represents the BodeQ curve of the bulk acoustic wave resonator in the prior art. The maximum vertical value point of the curve is the Qmax value, and the BodeQ of the bulk acoustic wave resonator corresponding to the parallel resonant frequency is the parallel resonance Q value of the bulk acoustic wave resonator. It can be seen from the figure that the Qmax value and the parallel resonance Q value of the bulk acoustic wave resonator provided by the embodiment of the present invention are significantly better than those of the prior art.

[0110] Continuing to refer to FIG. 8 , after the first electrode layer 207 is formed, the sacrificial layer 202 is removed.

[0111] In this embodiment, after the sacrificial layer 202 is removed, the second electrode layer 203 is formed between the cavity 201 and the piezoelectric layer 204 and covers the cavity 201 .

[0112] Accordingly, an embodiment of the present invention further provides a bulk acoustic wave resonator device, which, please continue to refer to FIG8 , includes: an acoustic reflection layer; a first electrode layer 207, wherein the first electrode layer 207 includes a first resonating portion 207a, a first attenuation portion 207b located outside the first resonating portion 207a, the first attenuation portion 207b surrounding the first resonating portion 207a, and a first limiting portion 207c located outside the first attenuation portion 207b, the first limiting portion 207c surrounding the first attenuation portion 207b; a piezoelectric layer 204, wherein the piezoelectric layer 204 includes a first side 2041 and a first side 2042 adjacent to the first side 2043. 041, the first electrode layer 207 is located on the first side 2041, and the sound reflection layer is located on the second side 2042; the second electrode layer 203, the second electrode layer 203 is located on the second side 2042, the second electrode layer 203 corresponds to the first electrode layer 207, the second electrode layer 203 includes a second resonant portion 203a, and the second resonant portion 203a corresponds to the first resonant portion 207a; the resonant region 208, the resonant region 208 includes the first resonant portion 207a, the second resonant portion 203a, and the first resonant portion 207a. 07a and the piezoelectric layer 204 between the second resonant portion 203a; a first dielectric layer 205, the first dielectric layer 205 is located on the first side 2041, the first dielectric layer 205 includes a first dielectric portion 205a and a second dielectric portion 205b, the first dielectric portion 205a is located between a portion of the first attenuation portion 207b and the piezoelectric layer 204, and the second dielectric portion 205b is located between the first limiting portion 207c and the piezoelectric layer 204; a first load layer 206, the first load layer 206 is located on the first side 2041, and the first load layer 206 corresponds to The first limiting portion 207c and the second dielectric portion 205b; a first attenuation zone 209 located outside the resonance zone 208, suitable for attenuating sound waves, the first attenuation zone 209 surrounds the resonance zone 208, the first attenuation zone 209 includes the first attenuation portion 207b and the first dielectric portion 205a; a first limiting zone 210 located outside the first attenuation zone 209, suitable for reflecting sound waves, the first limiting zone 210 surrounds the first attenuation zone 209, the first limiting zone 210 includes the first limiting portion 207c, the second dielectric portion 205b and the first load layer 206.

[0113] The first dielectric layer 205 is located between the first attenuation portion 207b, the first limiting portion 207c and the piezoelectric layer 204. Therefore, the first attenuation area 209 and the first limiting area 210 corresponding to the first dielectric layer 205 do not undergo acoustic-to-electrical conversion, and thus do not excite additional parasitic resonances. Since the cutoff frequency of the first attenuation zone 209 matches (for example, is equal to or less than) the cutoff frequency of the resonance zone 208, and the acoustic impedance of the first restriction zone 210 is mismatched with the acoustic impedance of the first attenuation zone 209, that is, the impedance difference is relatively large, the main transverse mode can first pass through the first attenuation zone 209 without being affected, and then be fully reflected back to the resonance zone 208 in the first restriction zone 210, thereby significantly reducing the transverse leakage wave; however, the high-order transverse parasitic modes entering the first attenuation zone 209 will experience attenuation. By reasonably setting the width of the first attenuation zone 209, the high-order transverse parasitic modes can be fully attenuated in the first attenuation zone 209, and only a small amount or even no high-order transverse parasitic modes can enter the first restriction zone 210, thereby preventing the high-order transverse parasitic modes from being reflected back to the resonance zone 208 and coupling with the main transverse mode, thereby improving the parallel impedance value and the corresponding Q value.

[0114] In this embodiment, the sound reflection layer includes a cavity 201 , and the second electrode layer 203 is located between the piezoelectric layer 204 and the cavity 201 , and covers the cavity 201 .

[0115] In this embodiment, the BAW resonator further includes a substrate 200 , in which the cavity 201 is embedded.

[0116] In this embodiment, the second electrode layer 203 further includes a second non-resonant portion 203 b , which is located outside the second resonant portion 203 a and surrounds the second resonant portion 203 a .

[0117] In this embodiment, the second non-resonant portion 203 b corresponds to the first attenuation portion 207 b and the first limiting portion 207 c.

[0118] In this embodiment, the first attenuation zone 209 further includes: a second non-resonant portion 203 b corresponding to the first attenuation portion 207 b.

[0119] In this embodiment, the first limiting region 210 further includes: a second non-resonant portion 203 b corresponding to the first limiting portion 207 c .

[0120] It should be noted that the first attenuation portion 207b includes a first sub-portion 207b1 and a second sub-portion 207b2, and the second sub-portion 207b2 is located outside the first sub-portion 207b1; the angle between the first sub-portion 207b1 and the first resonant portion 207a is greater than or equal to 90° and less than 180°; the angle between the first sub-portion 207b1 and the second sub-portion 207b2 is greater than or equal to 90° and less than 180°.

[0121] 8 , in this embodiment, the angle between the first sub-portion 207b1 and the first resonant portion 207a is equal to 90°, and the angle between the first sub-portion 207b1 and the second sub-portion 207b2 is equal to 90°.

[0122] In this embodiment, the first dielectric portion 205 a is located between the second sub-portion 207 b 2 and the piezoelectric layer 204 ; the first dielectric portion 205 a is located outside the first sub-portion 207 b 1 .

[0123] Please continue to refer to Figure 9. In other embodiments, the angle between the first sub-section 207b1 and the first resonant section 207a is greater than 90° and less than 180°, and the angle between the first sub-section 207b1 and the second sub-section 207b2 is greater than 90° and less than 180°; the first dielectric section 205a is also located between part of the first sub-section 207b1 and the piezoelectric layer 204.

[0124] It should be noted that the thickness range of the first dielectric layer 205 includes: 0.1t to 2t, where t represents the thickness of the first electrode layer 207; the width range of the first dielectric portion 205a includes: 0.2s to 6s, where s represents the thickness of the stacked structure of the resonance zone 208.

[0125] It should be noted that the thickness of the first load layer 206 ranges from 0.1t to 3t, where t represents the thickness of the first electrode layer 207. The width of the first load layer 206 ranges from 0.2s to 6s, where s represents the thickness of the stacked structure of the resonant region 208. In this embodiment, the material density of the first load layer 206 is greater than or equal to the material density of the first electrode layer 207.

[0126] In this embodiment, the first load layer 206 is located between the second dielectric portion 205 b and the first limiting portion 207 c .

[0127] It should be noted that the distance between the outer edge of the first electrode layer 207 and the outer edge of the first load layer 206 ranges from -2s to 2s, where s represents the thickness of the stacked structure of the resonant region 208. In this embodiment, the distance between the outer edge of the first electrode layer 207 and the outer edge of the first load layer 206 is 0.

[0128] FIG10 is a schematic structural diagram of a bulk acoustic wave resonator device according to another embodiment of the present invention.

[0129] This embodiment further describes the method for forming the bulk acoustic wave resonator device based on the above embodiment. The rest of the method is the same as the above embodiment, except that forming the acoustic reflection layer includes forming a Bragg reflection layer. This will be described in detail below with reference to the accompanying drawings.

[0130] Please refer to FIG10 , where a sound reflecting layer is formed.

[0131] In this embodiment, forming the acoustic reflection layer includes forming a Bragg reflection layer 301 .

[0132] In this embodiment, forming the acoustic reflection layer further includes: providing a substrate 300 , and the Bragg reflection layer 301 is formed on the substrate 300 .

[0133] In this embodiment, the second electrode layer 203 further includes a first non-resonant portion, which is located outside and surrounds the second resonant portion 203a. The first non-resonant portion corresponds to the first attenuation portion 207b and the first limiting portion 207c. The first attenuation region 209 further includes the first non-resonant portion corresponding to the first attenuation portion 207b, and the first limiting region 210 further includes the first non-resonant portion corresponding to the first limiting portion 207c. It should be noted that in this embodiment, the first non-resonant portion of the second electrode layer 203 is the same as the second non-resonant portion 203b of the second electrode layer 203 in the aforementioned embodiment ( FIG. 8 ).

[0134] Please continue to refer to FIG10 . After the sound reflection layer is formed, the formation process of the bulk acoustic wave resonator is consistent with the above embodiment. For details, please refer to FIG3 to FIG8 , which will not be described again here.

[0135] Correspondingly, a bulk acoustic wave resonance device is also provided in an embodiment of the present invention. Please continue to refer to Figure 10. The rest is the same as the above embodiment (Figure 8), except that the acoustic reflection layer includes the Bragg reflection layer 301 located on the substrate 300.

[0136] FIG11 is a schematic structural diagram of a bulk acoustic wave resonator device in another embodiment of the present invention.

[0137] This embodiment further describes the method for forming the BAW resonator device based on the above embodiment. The remaining details are the same as those of the above embodiment, with the exception that the first limiting portion is located between the second dielectric portion and the first load layer. This will be described in detail below with reference to the accompanying drawings.

[0138] Referring to FIG. 11 , after the first electrode layer 207 is formed, the first support layer 206 is formed.

[0139] In this embodiment, the first electrode layer 207 is formed after the first dielectric layer 205 is formed (please continue to refer to Figure 6), and the first load layer 206 is formed after the first electrode layer 207 is formed, that is, the first limiting portion 207c is located between the second dielectric portion 205b and the first load layer 206.

[0140] In this embodiment, the material relationship between the first load layer 206 and the first electrode layer 207, the area division of the first electrode layer 207, etc. are the same as those in the above embodiment (please continue to refer to Figure 8). Please refer to Figures 2 to 8 for details and will not be repeated here.

[0141] Correspondingly, a bulk acoustic wave resonance device is also provided in an embodiment of the present invention. Please continue to refer to Figure 11. The rest is the same as the above embodiment (Figure 8), except that the first limiting portion 207c is located between the second dielectric portion 205b and the first load layer 206.

[0142] FIG12 is a schematic structural diagram of a bulk acoustic wave resonator device in another embodiment of the present invention.

[0143] This embodiment further describes the method for forming the bulk acoustic wave resonator device based on the above embodiment, and is otherwise the same as the above embodiment except that it further includes forming a second attenuation zone.

[0144] Please refer to Figure 12. The first electrode layer 207 also includes a second attenuation portion 207d located outside the first limiting portion 207c, and the second attenuation portion 207d surrounds the first limiting portion 207c; the first dielectric layer 205 also includes a third dielectric portion 205c, and the third dielectric portion 205c is located between the piezoelectric layer 204 and the second attenuation portion 207d.

[0145] In this embodiment, it also includes: a second attenuation zone 211 formed outside the first restriction zone 210, suitable for attenuating high-order lateral sound waves that are not reflected, the second attenuation zone 211 surrounds the first restriction zone 210, and the second attenuation zone 211 includes a second attenuation portion 207d and the third dielectric portion 205c.

[0146] It should be noted that the distance between the outer edge of the first electrode layer 207 and the outer edge of the first load layer 206 ranges from -2s to 2s, where s represents the thickness of the stacked structure of the resonant region 208. In this embodiment, the distance between the outer edge of the first electrode layer 207 and the outer edge of the first load layer 206 is a positive value.

[0147] Correspondingly, a bulk acoustic wave resonance device is also provided in an embodiment of the present invention. Please continue to refer to Figure 12. The rest is the same as the above embodiment (Figure 8), except that the first electrode layer 207 also includes a second attenuation portion 207d located outside the first limiting portion 207c, and the second attenuation portion 400a surrounds the first limiting portion; the first dielectric layer 205 also includes a third dielectric portion 205c, and the third dielectric portion 205c is located between the piezoelectric layer 204 and the second attenuation portion 207d; the bulk acoustic wave resonance device also includes: a second attenuation zone 211 located outside the first limiting zone 210, suitable for attenuating high-order transverse sound waves that are not reflected, the second attenuation zone 211 surrounds the first limiting zone 210, and the second attenuation zone 211 includes the second attenuation portion 400a and the third dielectric portion 205c.

[0148] 13 to 26 are schematic structural diagrams of various steps of a method for forming a bulk acoustic wave resonator device in another embodiment of the present invention.

[0149] Referring to FIG. 13 , a sacrificial substrate 400 is provided.

[0150] 14 , a piezoelectric layer 401 is formed on one side of the sacrificial substrate 400 to cover the sacrificial substrate 400 . The piezoelectric layer 401 includes a first side 4011 and a second side 4012 opposite to the first side 4011 . The sacrificial substrate 400 is located on the first side 4011 .

[0151] It should be noted that the material of the piezoelectric layer 401 includes: lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate, aluminum nitride, aluminum nitride alloy, gallium nitride or zinc oxide.

[0152] In this embodiment, the material of the piezoelectric layer 401 is aluminum nitride or aluminum nitride alloy.

[0153] Referring to FIG. 15 , a second electrode layer 402 is formed and located on the second side 4012 . The second electrode layer 402 includes a second resonant portion 402 a .

[0154] In this embodiment, the second electrode layer 402 is located on the second side 4012 and contacts the piezoelectric layer 401 , that is, the second electrode layer 402 is the lower electrode layer of the BAW resonator.

[0155] In this embodiment, the second electrode layer 402 further includes a third non-resonant portion 402 b . The third non-resonant portion 402 b is located outside the second resonant portion 402 a and surrounds the second resonant portion 402 a .

[0156] Referring to FIG. 16 , a sacrificial layer 403 is formed on the second side 4012 .

[0157] In this embodiment, the sacrificial layer 403 covers the second electrode layer 402 . After the sacrificial layer 403 is subsequently removed to form a cavity, the second electrode layer 402 is located in the cavity.

[0158] Referring to FIG. 17 , an intermediate layer 404 is formed on the second side 4012 . The intermediate layer 404 covers the sacrificial layer 403 and the piezoelectric layer 401 .

[0159] Referring to FIG. 18 , a first sub-bonding layer 405 is formed and located on the second side 4012 . The first sub-bonding layer 405 covers the intermediate layer 404 .

[0160] In this embodiment, the material of the first sub-bonding layer 405 is the same as the material of the intermediate layer 404. In other embodiments, the material of the first sub-bonding layer 405 and the material of the intermediate layer 404 may be different.

[0161] Referring to FIG. 19 , a device substrate 406 is provided.

[0162] Referring to FIG. 20 , a second sub-bonding layer 407 is formed on one side of the device substrate 406 to cover the device substrate 406 .

[0163] In this embodiment, the material of the second sub-bonding layer 407 is the same as that of the first sub-bonding layer 405. In other embodiments, the material of the second sub-bonding layer 407 may be different from that of the first sub-bonding layer 405.

[0164] Please refer to FIG. 21 , the first sub-bonding layer 405 and the second sub-bonding layer 407 are bonded.

[0165] In this embodiment, after the first sub-bonding layer 405 and the second sub-bonding layer 407 are bonded, the device substrate 406 and the second sub-bonding layer are located on the second side 4012 .

[0166] Referring to FIG. 22 , after bonding the first sub-bonding layer 405 and the second sub-bonding layer 407 , the sacrificial substrate 400 is removed.

[0167] Since the sacrificial substrate 400 only provides temporary support for forming the piezoelectric layer 401 , the second electrode layer 402 , the sacrificial layer 403 and the intermediate layer 404 and is not a final retained structure, it can be removed after bonding.

[0168] 23 , a first dielectric layer 408 is formed on the first side 4011 . The first dielectric layer 408 includes a first dielectric portion 408 a and a second dielectric portion 408 b .

[0169] It should be noted that the material of the first dielectric layer 408 includes silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride or air.

[0170] In this embodiment, the first dielectric layer 408 is made of silicon oxide.

[0171] In this embodiment, the first dielectric layer 408 is formed on one side of the piezoelectric layer 401 and contacts the piezoelectric layer 401 .

[0172] It should be noted that the method for forming the first dielectric layer 408 includes: forming a first dielectric material layer (not shown) on one side of the piezoelectric layer 401 ; and patterning the first dielectric material layer to form the first dielectric layer 408 .

[0173] Referring to FIG. 24 , a first load layer 409 is formed and located on the first side 4011 . The first load layer 409 corresponds to the second dielectric portion 408 b .

[0174] In this embodiment, the first load layer 409 is located on one side of the second dielectric portion 408 b and is in contact with the second dielectric portion 408 b.

[0175] It should be noted that the material of the first load layer 409 includes: molybdenum, tungsten, platinum, palladium, gold, chromium, tantalum or iridium.

[0176] Please refer to Figure 25, a first electrode layer 410 is formed, which includes a first resonating portion 410a, a first attenuation portion 410b located outside the first resonating portion 410a, the first attenuation portion 410b surrounds the first resonating portion 410a, and a first limiting portion 410c located outside the first attenuation portion 410b, the first limiting portion 410c surrounds the first attenuation portion 410b.

[0177] In this embodiment, the first electrode layer 410 is formed on the first side 4011 , and the first resonator 410 a contacts the piezoelectric layer 401 , that is, the first electrode layer 410 is an upper electrode layer of the BAW resonator.

[0178] In this embodiment, the second electrode layer 402 corresponds to the first electrode layer 410 , and the second resonant portion 402 a corresponds to the first resonant portion 410 a .

[0179] In this embodiment, the first dielectric portion 408 a is located between a portion of the first attenuation portion 410 b and the piezoelectric layer 401 , and the second dielectric portion 408 b is located between the first limiting portion 410 c and the piezoelectric layer 401 .

[0180] In this embodiment, the first load layer 409 corresponds to the first limiting portion 410 c . Specifically, the first load layer 409 is formed between the second dielectric portion 408 b and the first limiting portion 410 c .

[0181] In other embodiments, the first load layer 409 may be formed after the first electrode layer 410 is formed, that is, the first limiting portion 410 c is located between the second dielectric portion 408 b and the first load layer 409 .

[0182] It should be noted that the first attenuation portion 410b includes a first sub-portion 410b1 and a second sub-portion 410b2, and the second sub-portion 410b1 is located outside the first sub-portion 410b1; the angle between the first sub-portion 410b1 and the first resonant portion 410a is greater than or equal to 90° and less than 180°; the angle between the first sub-portion 410b1 and the second sub-portion 410b2 is greater than or equal to 90° and less than 180°.

[0183] 25 , in this embodiment, the angle between the first sub-portion 410b1 and the first resonant portion 410a is equal to 90°, and the angle between the first sub-portion 410b1 and the second sub-portion 410b2 is equal to 90°.

[0184] In this embodiment, the first dielectric portion 408a is located between the second sub-portion 410b2 and the piezoelectric layer 401; the first dielectric portion 408a is located outside the first sub-portion 410b1.

[0185] In other embodiments, the angle between the first sub-section 410b1 and the first resonant section 410a is greater than 90° and less than 180°, and the angle between the first sub-section 410b1 and the second sub-section 410b2 is greater than 90° and less than 180°; the first dielectric section 408a is also located between part of the first sub-section 410b1 and the piezoelectric layer 401.

[0186] In this embodiment, the method further includes forming a resonance region 411 , wherein the resonance region 411 includes the first resonance portion 410 a , the second resonance portion 402 a , and the piezoelectric layer 401 formed between the first resonance portion 410 a and the second resonance portion 402 a .

[0187] In this embodiment, the third non-resonant portion 402 b corresponds to the first attenuation portion 410 b and the first limiting portion 410 c .

[0188] In this embodiment, it also includes: a first attenuation zone 412 formed outside the resonance zone 411, suitable for attenuating sound waves, the first attenuation zone 412 surrounds the resonance zone 411, the first attenuation zone 412 includes a first attenuation portion 410b, the first dielectric portion 408a, and the third non-resonant portion 402b corresponding to the first attenuation portion 410b; a first restriction zone 413 formed outside the first attenuation zone 412, suitable for reflecting sound waves, the first restriction zone 413 surrounds the first attenuation zone 412, the first restriction zone 413 includes a first restriction portion 410c, the second dielectric portion 408b, the first load layer 409, and the third non-resonant portion 402b corresponding to the first restriction portion 410c.

[0189] It should be noted that the thickness range of the first dielectric layer 408 includes: 0.1t to 2t, where t represents the thickness of the first electrode layer 410; the width range of the first dielectric portion 408a includes: 0.2s to 6s, where s represents the thickness of the stacked structure of the resonance zone 411 (for example, the sum of the thicknesses of the first resonance portion 410a, the second resonance portion 402a and the piezoelectric layer 401).

[0190] It should be noted that the thickness range of the first load layer 409 includes: 0.1t to 3t, where t represents the thickness of the first electrode layer 410; the width range of the first load layer 409 includes: 0.2s to 6s, where s represents the thickness of the stacked structure of the resonance zone 411.

[0191] In this embodiment, the material density of the first load layer 409 is greater than or equal to the material density of the first electrode layer 410, which is used to increase the overall mass of the first restriction area 413, thereby increasing the difference between the acoustic impedance of the first restriction area 413 and the acoustic impedance of the resonance area 411, thereby forming an acoustic impedance mismatch.

[0192] It should be noted that the spacing between the outer edge of the first electrode layer 410 and the outer edge of the first load layer 409 ranges from -2s to 2s, where s represents the thickness of the stacked structure of the resonant region 411. A negative spacing value indicates that the outer edge of the first electrode layer 410 is located inside the outer edge of the first load layer 409 (i.e., the first load layer 409 is not covered by the first electrode layer 410); a positive spacing value indicates that the outer edge of the first electrode layer 410 is located outside the outer edge of the first load layer 409 (i.e., the first load layer 409 is covered by the first electrode layer 410). In this embodiment, the spacing between the outer edges of the first electrode layer 410 and the outer edges of the first load layer 409 is 0 (i.e., flush).

[0193] The first dielectric layer 408 is located between the first attenuation portion 410b, the first limiting portion 410c and the piezoelectric layer 401. Therefore, the first attenuation area 412 and the first limiting area 413 corresponding to the first dielectric layer 408 do not undergo acoustic-to-electrical conversion, and thus do not excite additional parasitic resonances. Since the cutoff frequency of the first attenuation zone 412 matches (for example, is equal to or less than) the cutoff frequency of the resonance zone 411, and the acoustic impedance of the first restriction zone 413 is mismatched with the acoustic impedance of the first attenuation zone 412, that is, the impedance difference is large, the main transverse mode can first pass through the first attenuation zone 412 without being affected, and then be fully reflected back to the resonance zone 411 in the first restriction zone 413, thereby greatly reducing the transverse leakage wave; however, the high-order transverse parasitic modes entering the first attenuation zone 412 will experience attenuation. By reasonably setting the width of the first attenuation zone 412, the high-order transverse parasitic modes can be fully attenuated in the first attenuation zone 412, and only a small amount or even no high-order transverse parasitic modes enter the first restriction zone 413, thereby preventing the high-order transverse parasitic modes from being reflected back to the resonance zone 411 and coupling with the main transverse mode, thereby improving the parallel impedance value and the corresponding Q value.

[0194] Referring to FIG. 26 , after forming the first electrode layer 410 , the sacrificial layer 403 is removed to form a cavity 414 . The cavity 414 is embedded in the intermediate layer 404 , and an opening of the cavity 414 is located at the second side 4012 .

[0195] In this embodiment, the cavity 414 is formed on the second side 4012 , the second electrode layer 402 is formed between the cavity 414 and the piezoelectric layer 401 , and the second electrode layer 402 is formed in the cavity 414 .

[0196] It should be noted that, in this embodiment, the sound reflection layer includes the cavity 414 .

[0197] 26 , a BAW resonator is also provided in the embodiment of the present invention. The structure of the BAW resonator can be specifically described with reference to the previous descriptions of FIG. 13 to FIG. 26 , and will not be further elaborated here.

[0198] FIG27 is a schematic structural diagram of a bulk acoustic wave resonator device in another embodiment of the present invention.

[0199] This embodiment further describes the method for forming the BAW resonator based on the above embodiment ( FIG. 26 ), and is otherwise identical to the above embodiment except that it further includes forming a second attenuation region. This will be described in detail below with reference to the accompanying drawings.

[0200] Please refer to Figure 27. The first electrode layer 410 also includes a second attenuation portion 410d located outside the first limiting portion 410c, and the second attenuation portion 410d surrounds the first limiting portion 410c; the first dielectric layer 408 also includes a third dielectric portion 408c, and the third dielectric portion 408c is located between the piezoelectric layer 204 and the second attenuation portion 410d.

[0201] In this embodiment, it also includes: a second attenuation zone 415 formed outside the first restriction zone 413, suitable for attenuating high-order lateral sound waves that are not reflected, the second attenuation zone 415 surrounds the first restriction zone 413, and the second attenuation zone 415 includes a second attenuation portion 410d and the third dielectric portion 408c.

[0202] It should be noted that the distance between the outer edge of the first electrode layer 410 and the outer edge of the first load layer 409 ranges from -2s to 2s, where s represents the thickness of the stacked structure of the resonant region 411. In this embodiment, the distance between the outer edge of the first electrode layer 410 and the outer edge of the first load layer 409 is a positive value.

[0203] Correspondingly, a bulk acoustic wave resonance device is also provided in an embodiment of the present invention. Please continue to refer to Figure 27. The rest is the same as the above embodiment (Figure 26), except that the first electrode layer 410 also includes a second attenuation portion 410d located outside the first limiting portion 410c, and the second attenuation portion 400a surrounds the first limiting portion; the first dielectric layer 408 also includes a third dielectric portion 408c, and the third dielectric portion 408c is located between the piezoelectric layer 204 and the second attenuation portion 410d; the bulk acoustic wave resonance device also includes: a second attenuation zone 415 located outside the first limiting zone 413, suitable for attenuating high-order transverse sound waves that are not reflected, the second attenuation zone 415 surrounds the first limiting zone 413, and the second attenuation zone 415 includes the second attenuation portion 400a and the third dielectric portion 408c.

[0204] 28 to 41 are schematic structural diagrams of various steps of a method for forming a bulk acoustic wave resonator device in another embodiment of the present invention.

[0205] Referring to FIG. 28 , a sacrificial substrate 500 is provided.

[0206] Please refer to Figure 29. A piezoelectric layer 501 is formed on one side of the sacrificial substrate 500 to cover the sacrificial substrate 500. The piezoelectric layer 501 includes a first side 5011 and a second side 5012 opposite to the first side 5011. The sacrificial substrate 500 is located on the second side 5012.

[0207] It should be noted that the material of the piezoelectric layer 501 includes: lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate, aluminum nitride, aluminum nitride alloy, gallium nitride or zinc oxide.

[0208] In this embodiment, the material of the piezoelectric layer 501 is aluminum nitride or aluminum nitride alloy.

[0209] Referring to FIG. 30 , a first dielectric layer 502 is formed and located on the first side 5011 . The first dielectric layer 502 includes a first dielectric portion 502 a and a second dielectric portion 502 b .

[0210] It should be noted that the material of the first dielectric layer 502 includes: silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride or air.

[0211] In this embodiment, the material of the first dielectric layer 502 is silicon oxide.

[0212] In this embodiment, the first dielectric layer 502 is formed on one side of the piezoelectric layer 501 and is in contact with the piezoelectric layer 501 .

[0213] The method for forming the first dielectric layer 502 includes: forming a first dielectric material layer (not shown) on one side of the piezoelectric layer 501 ; and patterning the first dielectric material layer to form the first dielectric layer 502 .

[0214] Referring to FIG. 31 , a first load layer 503 is formed and located on the first side 5011 . The first load layer 503 corresponds to the second dielectric portion 502 b .

[0215] In this embodiment, the first load layer 503 is located on one side of the second dielectric portion 502 b and is in contact with the second dielectric portion 502 b.

[0216] It should be noted that the material of the first load layer 503 includes: molybdenum, tungsten, platinum, palladium, gold, chromium, tantalum or iridium.

[0217] Please refer to Figure 32, a first electrode layer 504 is formed, which includes a first resonant portion 504a, a first attenuation portion 504b located outside the first resonant portion 504a, the first attenuation portion 504b surrounds the first resonant portion 504a, and a first limiting portion 504c located outside the first attenuation portion 504b, the first limiting portion 504c surrounds the first attenuation portion 504b.

[0218] In this embodiment, the first electrode layer 504 is formed on the first side 5011 , and the first resonant portion 504 a contacts the piezoelectric layer 501 , that is, the first electrode layer 504 is the lower electrode layer of the BAW resonator.

[0219] In this embodiment, the first dielectric portion 502 a is located between a portion of the first attenuation portion 504 b and the piezoelectric layer 501 , and the second dielectric portion 502 b is located between the first limiting portion 504 c and the piezoelectric layer 501 .

[0220] In this embodiment, the first load layer 503 corresponds to the first limiting portion 504 c . Specifically, the first load layer 503 is formed between the second dielectric portion 502 b and the first limiting portion 504 c .

[0221] In other embodiments, the first load layer 503 may also be formed after the first electrode layer 504 is formed, that is, the first limiting portion 504 c may also be located between the first load layer 503 and the second dielectric portion 502 b .

[0222] It should be noted that the first attenuation portion 504b includes a first sub-portion 504b1 and a second sub-portion 504b2, and the second sub-portion 504b2 is located outside the first sub-portion 504b1; the angle between the first sub-portion 504b1 and the first resonant portion 504a is greater than or equal to 90° and less than 180°; the angle between the first sub-portion 504b1 and the second sub-portion 504b2 is greater than or equal to 90° and less than 180°.

[0223] Continuing to refer to FIG. 32 , in this embodiment, the angle between the first sub-portion 504 b 1 and the first resonant portion 504 a is equal to 90 degrees, and the angle between the first sub-portion 504 b 1 and the second sub-portion 504 b 2 is equal to 90 degrees.

[0224] In this embodiment, the first dielectric portion 502a is located between the second sub-portion 504b2 and the piezoelectric layer 501; the first dielectric portion 502a is located outside the first sub-portion 504b1.

[0225] In other embodiments, the angle between the first sub-section 504b1 and the first resonant section 504a is greater than 90° and less than 180°, and the angle between the first sub-section 504b1 and the second sub-section 504b2 is greater than 90° and less than 180°; the first dielectric section 502a is also located between part of the first sub-section 504b1 and the piezoelectric layer 501.

[0226] Referring to FIG. 33 , a sacrificial layer 505 is formed on the first side 5011 .

[0227] In this embodiment, the sacrificial layer 505 covers the first electrode layer 504, the first dielectric layer 502 and the first load layer 503. After the sacrificial layer 505 is subsequently removed to form a cavity, the first electrode layer 504, the first dielectric layer 502 and the first load layer 503 are formed between the cavity and the piezoelectric layer 501, and the first electrode layer 504, the first dielectric layer 502 and the first load layer 503 are formed in the cavity.

[0228] Referring to FIG. 34 , an intermediate layer 506 is formed on the first side 5011 . The intermediate layer 506 covers the sacrificial layer 505 and the piezoelectric layer 501 .

[0229] Referring to FIG. 35 , a first sub-bonding layer 507 is formed and located on the first side 5011 . The first sub-bonding layer 507 covers the intermediate layer 506 .

[0230] In this embodiment, the material of the first sub-bonding layer 507 is the same as that of the intermediate layer 506. In other embodiments, the material of the first sub-bonding layer 507 may be different from that of the intermediate layer 506. Referring to FIG36 , a device substrate 508 is provided.

[0231] Referring to FIG. 37 , a second sub-bonding layer 509 is formed on one side of the device substrate 508 .

[0232] In this embodiment, the material of the second sub-bonding layer 509 is the same as that of the first sub-bonding layer 507. In other embodiments, the material of the second sub-bonding layer 509 may be different from that of the first sub-bonding layer 507.

[0233] Please refer to FIG. 38 , the first sub-bonding layer 507 and the second sub-bonding layer 509 are bonded.

[0234] In this embodiment, after the first sub-bonding layer 507 and the second sub-bonding layer 509 are bonded, the device substrate 508 and the second sub-bonding layer 509 are located on the first side 5011 .

[0235] Please refer to FIG. 39 , after bonding the first sub-bonding layer 507 and the second sub-bonding layer 509 , the sacrificial substrate 500 is removed.

[0236] Since the sacrificial substrate 500 only provides temporary support for forming the piezoelectric layer 501 , the first electrode layer 504 , the sacrificial layer 505 and the intermediate layer 506 and is not a final retained structure, it can be removed after bonding.

[0237] 40 , after the sacrificial substrate 500 is removed, a second electrode layer 510 is formed on the second side 5012 . The second electrode layer 510 includes a second resonant portion 510 a .

[0238] In this embodiment, the second electrode layer 510 is located on the second side 5012 and contacts the piezoelectric layer 501 , that is, the second electrode layer 510 is the upper electrode layer of the BAW resonator.

[0239] In this embodiment, the second electrode layer 510 further includes a fourth non-resonant portion 510b. The fourth non-resonant portion 510b is located outside the second resonant portion 510a and surrounds the second resonant portion 510a. The fourth non-resonant portion 510b corresponds to the first attenuation portion 504b and the first limiting portion 504c.

[0240] In this embodiment, the second electrode layer 510 corresponds to the first electrode layer 504 , and the second resonant portion 510 a corresponds to the first resonant portion 504 a .

[0241] In this embodiment, the method further includes forming a resonance region 511 , wherein the resonance region 511 includes the first resonance portion 504 a , the second resonance portion 510 a , and the piezoelectric layer 501 formed between the first resonance portion 504 a and the second resonance portion 510 a .

[0242] In this embodiment, the present invention further includes: a first attenuation zone 512 formed outside the resonance zone 511, suitable for attenuating sound waves, the first attenuation zone 512 surrounds the resonance zone 511, and the first attenuation zone 512 includes a first attenuation portion 504b, the first dielectric portion 502a, and the fourth non-resonant portion 510b corresponding to the first attenuation portion 504b; a first restriction zone 513 formed outside the first attenuation zone 512, suitable for reflecting sound waves, the first restriction zone 513 surrounds the first attenuation zone 512, and the first restriction zone 513 includes a first restriction portion 504c, the second dielectric portion 502b, the first load layer 503, and the fourth non-resonant portion 510b corresponding to the first restriction portion 504c.

[0243] It should be noted that the thickness range of the first dielectric layer 502 includes: 0.1t to 2t, where t represents the thickness of the first electrode layer 504; the width range of the first dielectric portion 502a includes: 0.2s to 6s, where s represents the thickness of the stacked structure of the resonance zone 511 (for example, the sum of the thicknesses of the first resonance portion 504a, the second resonance portion 510a and the piezoelectric layer 501).

[0244] It should be noted that the thickness range of the first load layer 503 includes: 0.1t to 3t, where t represents the thickness of the first electrode layer 504; the width range of the first load layer 503 includes: 0.2s to 6s, where s represents the thickness of the stacked structure of the resonance zone 511.

[0245] In this embodiment, the material density of the first load layer 503 is greater than or equal to the material density of the first electrode layer 504, which is used to increase the overall mass of the first restriction area 513, thereby increasing the difference between the acoustic impedance of the first restriction area 513 and the acoustic impedance of the resonance area, thereby forming an acoustic impedance mismatch.

[0246] It should be noted that the spacing between the outer edge of the first electrode layer 504 and the outer edge of the first load layer 503 ranges from -2s to 2s, where s represents the thickness of the stacked structure of the resonant region 511. A negative spacing value indicates that the outer edge of the first electrode layer 504 is located inside the outer edge of the first load layer 503 (i.e., the first load layer 503 is not covered by the first electrode layer 504); a positive spacing value indicates that the outer edge of the first electrode layer 504 is located outside the outer edge of the first load layer 503 (i.e., the first load layer 503 is covered by the first electrode layer 504). In this embodiment, the spacing between the outer edges of the first electrode layer 504 and the outer edges of the first load layer 503 is 0 (i.e., flush).

[0247] The first dielectric layer 502 is located between the first attenuation portion 504b, the first limiting portion 504c and the piezoelectric layer 501. Therefore, the first attenuation area 512 and the first limiting area 513 corresponding to the first dielectric layer 502 do not undergo acoustic-to-electrical conversion, and thus do not excite additional parasitic resonances. Since the cutoff frequency of the first attenuation zone 512 matches (for example, is equal to or less than) the cutoff frequency of the resonance zone 511, and the acoustic impedance of the first restriction zone 513 is mismatched with the acoustic impedance of the first attenuation zone 512, that is, the impedance difference is large, the main transverse mode can first pass through the first attenuation zone 512 without being affected, and then be fully reflected back to the resonance zone in the first restriction zone 513, thereby greatly reducing the transverse leakage wave; however, the high-order transverse parasitic modes entering the first attenuation zone 512 will experience attenuation. By reasonably setting the width of the first attenuation zone 512, the high-order transverse parasitic modes can be fully attenuated in the first attenuation zone 512, and only a small amount or even no high-order transverse parasitic modes enter the first restriction zone 513, thereby preventing the high-order transverse parasitic modes from being reflected back to the resonance zone 511 and coupling with the main transverse mode, thereby improving the parallel impedance value and the corresponding Q value.

[0248] Please refer to FIG. 41 . After forming the second electrode layer 510 , the sacrificial layer 505 is removed to form a cavity 514 . The cavity 514 is embedded in the intermediate layer 506 . The opening of the cavity 514 is located at the first side 5011 .

[0249] In this embodiment, the cavity 514 is formed on the first side 5011 , and the first electrode layer 504 , the first dielectric layer 502 , and the first load layer 503 are formed in the cavity 514 .

[0250] It should be noted that, in this embodiment, the sound reflection layer includes the cavity 514 .

[0251] 41 , a BAW resonator is also provided in the embodiment of the present invention. The structure of the BAW resonator can be specifically described with reference to the previous descriptions of FIG. 28 to FIG. 41 , and will not be further elaborated here.

[0252] FIG42 is a schematic structural diagram of a bulk acoustic wave resonator device in another embodiment of the present invention.

[0253] This embodiment further describes the method for forming the BAW resonator based on the above embodiment ( FIG. 41 ). The rest of the method is the same as the above embodiment, except that it also includes forming a second attenuation zone. This will be described in detail below with reference to the accompanying drawings.

[0254] Please refer to Figure 42. The first electrode layer 504 also includes a second attenuation portion 504d located outside the first limiting portion 504c, and the second attenuation portion 504d surrounds the first limiting portion 504c; the first dielectric layer 502 also includes a third dielectric portion 502c, and the third dielectric portion 502c is located between the piezoelectric layer 501 and the second attenuation portion 504d.

[0255] In this embodiment, it also includes: a second attenuation zone 515 formed outside the first restriction zone 513, suitable for attenuating high-order lateral sound waves that are not reflected, the second attenuation zone 515 surrounds the first restriction zone 513, and the second attenuation zone 515 includes a second attenuation portion 504d and the third dielectric portion 502c.

[0256] It should be noted that the distance between the outer edge of the first electrode layer 504 and the outer edge of the first load layer 503 ranges from -2s to 2s, where s represents the thickness of the stacked structure of the resonant region 511. In this embodiment, the distance between the outer edge of the first electrode layer 504 and the outer edge of the first load layer 503 is a positive value.

[0257] Correspondingly, a bulk acoustic wave resonance device is also provided in an embodiment of the present invention. Please continue to refer to Figure 42. The rest is the same as the above embodiment (Figure 41), except that the first electrode layer 504 also includes a second attenuation portion 504d located outside the first limiting portion 504c, and the second attenuation portion 400a surrounds the first limiting portion; the first dielectric layer 502 also includes a third dielectric portion 502c, and the third dielectric portion 502c is located between the piezoelectric layer 501 and the second attenuation portion 504d; the bulk acoustic wave resonance device also includes: a second attenuation zone 515 located outside the first limiting zone 513, suitable for attenuating high-order transverse sound waves that are not reflected, the second attenuation zone 515 surrounds the first limiting zone 513, and the second attenuation zone 515 includes the second attenuation portion 400a and the third dielectric portion 502c.

[0258] FIG43 is a schematic structural diagram of each step of a method for forming a bulk acoustic wave resonator device in another embodiment of the present invention.

[0259] This embodiment further illustrates the method for forming a bulk acoustic wave resonator device based on the above embodiment ( FIG. 40 ). The remaining aspects are the same as those of the above embodiment, with the exception that the second electrode layer 510 further includes a third attenuation portion and a second limiting portion. This will be described in detail below with reference to the accompanying drawings.

[0260] 43 , a second dielectric layer 600 is formed and located on the second side 5012 . The second dielectric layer 600 includes a fourth dielectric portion 600 a and a fifth dielectric portion 600 b , forming a second load layer 601 and located on the second side 5012 .

[0261] In this embodiment, the formation process and materials of the second dielectric layer 600 and the second load layer 601 can be specifically referred to the relevant descriptions of the first dielectric layer 502 and the first load layer 503 in Figures 30 and 31, and will not be repeated here.

[0262] Please continue to refer to Figure 43 to form a second electrode layer 510. The second electrode layer 510 also includes a third attenuation portion 510c located outside the second resonant portion 510a, the third attenuation portion 510c surrounds the second resonant portion 510a, and a second limiting portion 510d located outside the third attenuation portion 510c, the second limiting portion 510d surrounds the third attenuation portion 510c.

[0263] It should be noted that, in this embodiment, the second electrode layer 510 does not have the fourth non-resonant portion 510 b as described in FIG. 40 and related descriptions.

[0264] In this embodiment, the fourth dielectric portion 600a is located between part of the third attenuation portion 510c and the piezoelectric layer 501, and the fifth dielectric portion 600b is located between the second limiting portion 510d and the piezoelectric layer 501; the second load layer 601 corresponds to the second limiting portion 510d and the fifth dielectric portion 600b.

[0265] In this embodiment, the remaining area division of the second electrode layer 510 and its positional relationship with other structures can be specifically described in Figure 40 and related descriptions, and will not be repeated here.

[0266] In this embodiment, the first attenuation zone 512 further includes a third attenuation portion 510 c and the fourth dielectric portion 600 a ; the first restriction zone 513 further includes a second restriction portion 510 d , the fifth dielectric portion 600 b and the second load layer 601 .

[0267] Continuing to refer to FIG. 43 , after forming the second electrode layer 510 , the sacrificial layer 505 is removed to form a cavity 514 . The cavity 514 is embedded in the intermediate layer 506 , and an opening of the cavity 514 is located at the first side 5011 .

[0268] In this embodiment, the positional relationship among the first electrode layer 504 , the first dielectric layer 502 , the first load layer 503 and the cavity 514 is specifically described in FIG41 and related descriptions, which will not be further elaborated here.

[0269] 43 , a BAW resonator is also provided in the embodiment of the present invention. The structure of the BAW resonator can be specifically described with reference to the previous descriptions of FIG. 28 to FIG. 41 and FIG. 43 , and will not be further elaborated here.

[0270] Correspondingly, the technical solution of the present invention further provides a filtering device, comprising the bulk acoustic wave resonator device as described in any of the above embodiments.

[0271] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A bulk acoustic wave resonator device, characterized in that: include: Sound reflecting layer; a first electrode layer, the first electrode layer including a first resonating portion, a first attenuation portion located outside the first resonating portion, the first attenuation portion surrounding the first resonating portion, and a first limiting portion located outside the first attenuation portion, the first limiting portion surrounding the first attenuation portion; a piezoelectric layer, the piezoelectric layer comprising a first side and a second side opposite to the first side, the first electrode layer being located on the first side, and the acoustic reflection layer being located on the first side or the second side; a second electrode layer, the second electrode layer being located on the second side, the second electrode layer corresponding to the first electrode layer, the second electrode layer including a second resonant portion, the second resonant portion corresponding to the first resonant portion; a resonance region, the resonance region including the first resonance portion, the second resonance portion, and the piezoelectric layer located between the first resonance portion and the second resonance portion; a first dielectric layer, the first dielectric layer being located on the first side, the first dielectric layer comprising a first dielectric portion and a second dielectric portion, the first dielectric portion being located between a portion of the first attenuation portion and the piezoelectric layer, and the second dielectric portion being located between the first limiting portion and the piezoelectric layer; a first load-bearing layer, the first load-bearing layer being located on the first side and corresponding to the first restricting portion and the second dielectric portion; a first attenuation zone located outside the resonance zone, adapted to attenuate sound waves, the first attenuation zone surrounding the resonance zone, the first attenuation zone comprising a first attenuation portion and the first dielectric portion; The first restriction zone located outside the first attenuation zone is suitable for reflecting sound waves. The first restriction zone surrounds the first attenuation zone and includes a first restriction portion, the second dielectric portion, and the first load layer.

2. The bulk acoustic wave resonator device according to claim 1, wherein The first attenuation section includes a first sub-section and a second sub-section, the second sub-section is located outside the first sub-section; the angle between the first sub-section and the first resonant section is greater than or equal to 90° and less than 180°; the angle between the first sub-section and the second sub-section is greater than or equal to 90° and less than 180°.

3. The bulk acoustic wave resonator device according to claim 2, wherein: The first dielectric portion is located between the second sub-portion and the piezoelectric layer; and the first dielectric portion is located outside the first sub-portion.

4. The bulk acoustic wave resonator device according to claim 3, wherein: The first dielectric portion is also located between a portion of the first sub-portion and the piezoelectric layer.

5. The bulk acoustic wave resonator device according to claim 1, wherein The thickness of the first dielectric layer ranges from 0.1t to 2t, where t represents the thickness of the first electrode layer; the width of the first dielectric portion ranges from 0.2s to 6s, where s represents the thickness of the resonant region stacked structure.

6. The bulk acoustic wave resonator device according to claim 1, wherein The thickness range of the first load layer includes: 0.1t to 3t, where t represents the thickness of the first electrode layer; the width range of the first load layer includes: 0.2s to 6s, where s represents the thickness of the resonant region stacked structure.

7. The bulk acoustic wave resonator device according to claim 1, wherein The material density of the first support layer is greater than or equal to the material density of the first electrode layer.

8. The bulk acoustic wave resonator device according to claim 1, wherein: The first load-bearing layer is located between the second dielectric portion and the first restriction portion.

9. The bulk acoustic wave resonator device according to claim 1, wherein: The first limiting portion is located between the second dielectric portion and the first load-bearing layer.

10. The bulk acoustic wave resonator device according to claim 1, wherein The distance between the outer edge of the first electrode layer and the outer edge of the first load layer ranges from -2s to 2s, where s represents the thickness of the resonant region stacked structure.

11. The bulk acoustic wave resonator device according to claim 1, wherein The first electrode layer further includes a second attenuation portion located outside the first limiting portion, and the second attenuation portion surrounds the first limiting portion; the first dielectric layer further includes a third dielectric portion, and the third dielectric portion is located between the piezoelectric layer and the second attenuation portion.

12. The bulk acoustic wave resonator device according to claim 11, wherein: Also includes: The second attenuation zone located outside the first restriction zone is suitable for attenuating sound waves. The second attenuation zone surrounds the first restriction zone and includes a second attenuation portion and the third dielectric portion.

13. The bulk acoustic wave resonator device according to claim 1, wherein The sound reflection layer includes: a cavity or a Bragg reflection layer.

14. The bulk acoustic wave resonator device according to claim 13, wherein: The acoustic reflection layer is a Bragg reflection layer, which is located on the second side. The second electrode layer is located between the Bragg reflection layer and the piezoelectric layer. The second electrode layer also includes a first non-resonant portion, which is located outside the second resonant portion and surrounds the second resonant portion. The first non-resonant portion corresponds to the first attenuation portion and the first limiting portion. The first attenuation zone also includes the first non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the first non-resonant portion corresponding to the first limiting portion.

15. The bulk acoustic wave resonator device according to claim 13, wherein: The sound reflection layer is a cavity, which is located on the second side. The second electrode layer is located between the cavity and the piezoelectric layer and covers the cavity. The second electrode layer also includes a second non-resonant portion, which is located outside the second resonant portion and surrounds the second resonant portion. The second non-resonant portion corresponds to the first attenuation portion and the first limiting portion. The first attenuation zone also includes the second non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the second non-resonant portion corresponding to the first limiting portion.

16. The bulk acoustic wave resonator device according to claim 13, wherein: The sound reflection layer is a cavity, which is located on the second side, the second electrode layer is located between the cavity and the piezoelectric layer, and the second electrode layer is located in the cavity. The second electrode layer also includes a third non-resonant portion, which is located outside the second resonant portion and surrounds the second resonant portion. The third non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes the third non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the third non-resonant portion corresponding to the first limiting portion.

17. The bulk acoustic wave resonator device according to claim 13, wherein: The acoustic reflection layer is a cavity located on the first side. The first electrode layer, the first dielectric layer, and the first load layer are located between the cavity and the piezoelectric layer. The first electrode layer, the first dielectric layer, and the first load layer are located in the cavity.

18. The bulk acoustic wave resonator device according to claim 17, wherein: The second electrode layer also includes a fourth non-resonant portion, which is located outside the second resonant portion and surrounds the second resonant portion, and the fourth non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes the fourth non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the fourth non-resonant portion corresponding to the first limiting portion.

19. The bulk acoustic wave resonator device according to claim 17, wherein: The second electrode layer further includes a third attenuation portion located outside the second resonating portion, the third attenuation portion surrounding the second resonating portion, and a second limiting portion located outside the third attenuation portion, the second limiting portion surrounding the third attenuation portion.

20. The bulk acoustic wave resonator device according to claim 19, wherein: Also includes: a second dielectric layer, the second dielectric layer being located on the second side, the second dielectric layer comprising a fourth dielectric portion and a fifth dielectric portion, the fourth dielectric portion being located between a portion of the third attenuation portion and the piezoelectric layer, and the fifth dielectric portion being located between the second limiting portion and the piezoelectric layer; A second load-bearing layer is located on the second side, and corresponds to the second limiting portion and the fifth dielectric portion.

21. The bulk acoustic wave resonator device according to claim 20, wherein: The first attenuation zone further includes a third attenuation portion and the fourth dielectric portion; the first restriction zone further includes a second restriction portion, the fifth dielectric portion and the second load layer.

22. A method for forming a bulk acoustic wave resonator device, characterized in that: include: forming a sound reflecting layer; forming a first electrode layer, the first electrode layer including a first resonating portion, a first attenuation portion located outside the first resonating portion, the first attenuation portion surrounding the first resonating portion, and a first limiting portion located outside the first attenuation portion, the first limiting portion surrounding the first attenuation portion; forming a piezoelectric layer, the piezoelectric layer including a first side and a second side opposite to the first side, the first electrode layer being formed on the first side, and the acoustic reflection layer being formed on the first side or the second side; forming a second electrode layer located on the second side, the second electrode layer corresponding to the first electrode layer, the second electrode layer including a second resonant portion, the second resonant portion corresponding to the first resonant portion; forming a resonance region, the resonance region including the first resonance portion, the second resonance portion, and the piezoelectric layer formed between the first resonance portion and the second resonance portion; forming a first dielectric layer located on the first side, the first dielectric layer comprising a first dielectric portion and a second dielectric portion, the first dielectric portion being located between a portion of the first attenuation portion and the piezoelectric layer, and the second dielectric portion being located between the first limiting portion and the piezoelectric layer; forming a first load-bearing layer located on the first side, wherein the first load-bearing layer corresponds to the first limiting portion and the second dielectric portion; a first attenuation zone formed outside the resonance zone, adapted to attenuate sound waves, the first attenuation zone surrounding the resonance zone, the first attenuation zone comprising a first attenuation portion and the first dielectric portion; The first restriction zone formed outside the first attenuation zone is suitable for reflecting sound waves. The first restriction zone surrounds the first attenuation zone and includes a first restriction portion, the second dielectric portion, and the first load layer.

23. The method for forming a bulk acoustic wave resonator device according to claim 22, wherein: The first attenuation section includes a first sub-section and a second sub-section, the second sub-section is located outside the first sub-section; the angle between the first sub-section and the first resonant section is greater than or equal to 90° and less than 180°; the angle between the first sub-section and the second sub-section is greater than or equal to 90° and less than 180°.

24. The method for forming a bulk acoustic wave resonator device according to claim 23, wherein: The first dielectric portion is located between the second sub-portion and the piezoelectric layer; and the first dielectric portion is located outside the first sub-portion.

25. The method for forming a bulk acoustic wave resonator device according to claim 24, wherein: The first dielectric portion is also located between a portion of the first sub-portion and the piezoelectric layer.

26. The method for forming a bulk acoustic wave resonator device according to claim 22, wherein: The first load layer is formed between the second dielectric portion and the first restriction portion.

27. The method for forming a bulk acoustic wave resonator device according to claim 22, wherein: After forming the first electrode layer, the first load layer is formed, and the first limiting portion is located between the second dielectric portion and the first load layer.

28. The method for forming a bulk acoustic wave resonator device according to claim 22, wherein: The first electrode layer further includes a second attenuation portion located outside the first limiting portion, and the second attenuation portion surrounds the first limiting portion; the first dielectric layer further includes a third dielectric portion, and the third dielectric portion is located between the piezoelectric layer and the second attenuation portion.

29. The method for forming a bulk acoustic wave resonator device according to claim 28, wherein: Also includes: The second attenuation zone formed outside the first restriction zone is suitable for attenuating sound waves. The second attenuation zone surrounds the first restriction zone and includes a second attenuation portion and the third dielectric portion.

30. The method for forming a bulk acoustic wave resonator device according to claim 22, wherein: Forming the sound reflection layer includes forming a cavity or forming a Bragg reflection layer.

31. The method for forming a bulk acoustic wave resonator device according to claim 30, wherein: The Bragg reflection layer is formed on the second side, the second electrode layer is formed between the Bragg reflection layer and the piezoelectric layer, the second electrode layer also includes a first non-resonant portion, the first non-resonant portion is located outside the second resonant portion and surrounds the second resonant portion, the first non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes the first non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the first non-resonant portion corresponding to the first limiting portion.

32. The method for forming a bulk acoustic wave resonator device according to claim 30, wherein: The cavity is formed on the second side, the second electrode layer is formed between the cavity and the piezoelectric layer and covers the cavity, the second electrode layer also includes a second non-resonant portion, the second non-resonant portion is located outside the second resonant portion and surrounds the second resonant portion, the second non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes the second non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the second non-resonant portion corresponding to the first limiting portion.

33. The method for forming a bulk acoustic wave resonator device according to claim 30, wherein: The cavity is formed on the second side, the second electrode layer is formed between the cavity and the piezoelectric layer, the second electrode layer is formed in the cavity, the second electrode layer also includes a third non-resonant portion, the third non-resonant portion is located outside the second resonant portion and surrounds the second resonant portion, the third non-resonant portion corresponds to the first attenuation portion and the first limiting portion; the first attenuation zone also includes the third non-resonant portion corresponding to the first attenuation portion, and the first limiting zone also includes the third non-resonant portion corresponding to the first limiting portion.

34. The method for forming a bulk acoustic wave resonator device according to claim 30, wherein: The cavity is formed on the first side, the first electrode layer, the first dielectric layer, and the first load layer are formed between the cavity and the piezoelectric layer, and the first electrode layer, the first dielectric layer, and the first load layer are formed in the cavity.

35. The method for forming a bulk acoustic wave resonator device according to claim 34, wherein: The first attenuation region further includes a fourth non-resonant portion corresponding to the first attenuation portion, and the first restriction region further includes the fourth non-resonant portion corresponding to the first restriction portion.

36. The method for forming a bulk acoustic wave resonator device according to claim 34, wherein: The second electrode layer further includes a third attenuation portion located outside the second resonating portion, the third attenuation portion surrounding the second resonating portion, and a second limiting portion located outside the third attenuation portion, the second limiting portion surrounding the third attenuation portion.

37. The method for forming a bulk acoustic wave resonator device according to claim 36, wherein: Also includes: A second dielectric layer is formed and located on the second side, the second dielectric layer includes a fourth dielectric portion and a fifth dielectric portion, the fourth dielectric portion is located between a portion of the third attenuation portion and the piezoelectric layer, and the fifth dielectric portion is located between the second limiting portion and the piezoelectric layer; a second load layer is formed and located on the second side, the second load layer corresponds to the second limiting portion and the fifth dielectric portion.

38. The method for forming a bulk acoustic wave resonator device according to claim 37, wherein: The first attenuation zone further includes a third attenuation portion and the fourth dielectric portion; the first restriction zone further includes a second restriction portion, the fifth dielectric portion and the second load layer.

39. A filtering device, characterized in that: include: A bulk acoustic wave resonator device according to any one of claims 1 to 21.

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