Bulk acoustic wave resonance device

Abstract

A bulk acoustic wave resonance device includes: an acoustic reflection layer; the first electrode layer comprises a first resonance part, a first attenuation part and a first limiting part; a piezoelectric layer; a second electrode layer including a second resonance portion; the resonance area comprises a first resonance part, a second resonance part and a piezoelectric layer between the first resonance part and the second resonance part; the first dielectric layer comprises a first dielectric part and a second dielectric part; the first load layer corresponds to the first limiting part and the second medium part; a first attenuation region outside the resonance region; a first confinement region outside the first attenuation region; and the distance between the edge of the first load layer and the edge of the first medium part is 0.5-5 microns. The first-order transverse mode can pass through the first attenuation area without being affected, and then is fully reflected back to the resonance area in the first limiting area, so that transverse leaky waves are reduced; the high-order lateral parasitic mode entering the first attenuation region is attenuated, and only a small number or even no high-order lateral parasitic mode enters the first confinement region, so that the parallel impedance value and the corresponding Q value can be improved.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor technology, and in particular to a bulk acoustic wave resonator. Background Technology

[0002] Radio frequency (RF) front-end chips in wireless communication devices include power amplifiers, antenna switches, RF filters, multiplexers (including duplexers), and low-noise amplifiers. Among these, 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.

[0003] Bulk acoustic wave (BAW) resonators have a high quality factor (Q value). Low insertion loss and high out-of-band rejection radio frequency (RF) filters made from BAW resonators, known as BAW filters, are among the mainstream RF filters used in mobile phones, base stations, and other wireless communication devices. The Q value is the quality factor of the resonator, defined as the center frequency divided by the resonator's 3dB bandwidth. BAW filters are typically used in frequencies ranging from 0.7GHz to 7GHz.

[0004] As wireless communication technology evolves, the number of frequency bands used increases. Simultaneously, with the application of technologies such as carrier aggregation and frequency band overlay, mutual interference between wireless frequency bands becomes increasingly severe. High-performance bulk acoustic wave technology can solve the problem of mutual interference between frequency bands. With the advent of the 5G era, wireless mobile networks have introduced higher communication frequency bands, and currently only bulk acoustic wave technology can solve the filtering problem of high-frequency bands.

[0005] However, bulk acoustic resonator devices still have many problems. Utility Model Content

[0006] The technical problem solved by this utility model is to provide a bulk acoustic resonator to further improve the Q of the acoustic resonator.

[0007] To address the aforementioned problems, this utility model provides a bulk acoustic resonator, comprising: an acoustic reflection layer; a first electrode layer, the first electrode layer including a first resonant portion, a first attenuation portion located outside the first resonant portion, the first attenuation portion surrounding the first resonant portion, and a first limiting portion located outside the first attenuation portion, the first limiting portion surrounding the first attenuation portion; a piezoelectric layer including 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 either 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 resonant region, the resonant region including the first resonant portion, the second resonant portion, and the piezoelectric layer located between the first resonant portion and the second resonant portion; and a first dielectric layer. Located on the first side, the first dielectric layer includes 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 confinement portion and the piezoelectric layer; a first load layer, located on the first side, corresponding to the first confinement portion and the second dielectric portion; a first attenuation region located outside the resonant region for attenuating sound waves, the first attenuation region surrounding the resonant region, the first attenuation region including the first attenuation portion and the first dielectric portion; a first confinement region located outside the first attenuation region for reflecting sound waves, the first confinement region surrounding the first attenuation region, the first confinement region including the first confinement portion, the second dielectric portion and the first load layer; wherein, there is a first spacing dimension between the edge of the first load layer near the resonant region and the edge of the first dielectric portion near the resonant region, the first spacing dimension ranging from 0.5 micrometers to 5 micrometers.

[0008] Optionally, the material of the first electrode layer is molybdenum.

[0009] Optionally, the thickness of the first electrode layer ranges from 200 nanometers to 350 nanometers.

[0010] Optionally, the material of the second electrode layer is molybdenum.

[0011] Optionally, the thickness of the second electrode layer ranges from 200 nanometers to 350 nanometers.

[0012] Optionally, the material of the piezoelectric layer includes aluminum nitride or scandium-doped aluminum nitride.

[0013] Optionally, the thickness of the piezoelectric layer ranges from 900 nanometers to 1100 nanometers.

[0014] Optionally, the material of the first load layer is metal, and the material density of the first load layer is greater than the material density of the first electrode layer and the second electrode layer.

[0015] Optionally, the material of the first load layer is platinum.

[0016] Optionally, the thickness of the first load layer ranges from 80 nanometers to 120 nanometers.

[0017] Optionally, the material of the first dielectric layer is silicon dioxide.

[0018] Optionally, the thickness of the first dielectric layer ranges from 80 nanometers to 120 nanometers.

[0019] Optionally, the first load layer is located between the second medium portion and the first limiting portion.

[0020] Optionally, the first limiting portion is located between the second medium portion and the first load layer.

[0021] Optionally, the first electrode layer further includes a second attenuation portion located outside the first limiting portion, the second attenuation portion surrounding the first limiting portion; the first dielectric layer further includes a third dielectric portion located between the piezoelectric layer and the second attenuation portion.

[0022] Optionally, there is a second spacing dimension between the edge of the first load layer away from the resonant region and the edge of the second attenuation portion away from the resonant region, the second spacing dimension ranging from 0.5 micrometers to 3 micrometers.

[0023] Optionally, it further includes: a second attenuation region located outside the first restriction region for attenuating sound waves, the second attenuation region surrounding the first restriction region, the second attenuation region including a second attenuation portion and the third dielectric portion.

[0024] Optionally, the acoustic reflective layer may include a cavity or a Bragg reflective layer.

[0025] Optionally, the operating frequency range of the bulk acoustic resonator is 2300MHz~2500MHz.

[0026] Compared with the prior art, the technical solution of this utility model has the following advantages:

[0027] In the bulk acoustic resonator of this invention, the first dielectric layer is located between the first attenuation section, the first confinement section, and the piezoelectric layer. Therefore, the first attenuation region and the first confinement region corresponding to the first dielectric layer will not excite significant parasitic resonances. Since the acoustic impedance of the first attenuation region matches (e.g., is equal to or less than) the acoustic impedance of the resonant region, while the acoustic impedance of the first confinement region is mismatched with that of the first attenuation region (i.e., the impedance difference is large), the first-order transverse mode can pass through the first attenuation region unaffected and then be fully reflected back to the resonant region from the first confinement region, thereby significantly reducing transverse leakage. However, higher-order transverse parasitic modes entering the first attenuation region will experience attenuation. By reasonably setting the width of the first attenuation region, higher-order transverse parasitic modes can be fully attenuated within the first attenuation region, with only a small number or even no higher-order transverse parasitic modes entering the first confinement region. This prevents higher-order transverse parasitic modes from reflecting back to the resonant region and coupling with the first-order transverse mode, thereby increasing the parallel impedance value and the corresponding Q value. Furthermore, the first spacing dimension ranges from 0.5 micrometers to 5 micrometers. When the first spacing dimension is less than 0.5 micrometers, it is smaller than half the wavelength of the transmitted wave, resulting in an insignificant attenuation effect. Moreover, the small spacing dimension makes it difficult to achieve precise alignment in photolithography. When the first spacing dimension is greater than 5 micrometers, it is too large, generating a large parasitic capacitance, which can easily lead to a decrease in the electromechanical coupling coefficient of the resonator. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a bulk acoustic resonator;

[0029] Figure 2 This is a schematic diagram of the structure of a bulk acoustic resonator device in one embodiment of this utility model;

[0030] Figure 3 This is a comparison chart of the real part amplitude of impedance and the quality factor as a function of frequency between the present invention and existing technologies.

[0031] Figure 4 This is a schematic diagram of the structure of a bulk acoustic resonator device in another embodiment of this utility model;

[0032] Figure 5 This is a schematic diagram of the structure of a bulk acoustic resonator device in another embodiment of this utility model;

[0033] Figure 6 This is a schematic diagram of the structure of a bulk acoustic resonator device in another embodiment of this utility model;

[0034] Figure 7 This is a schematic diagram of the structure of a bulk acoustic resonator device in another embodiment of this utility model;

[0035] Figure 8 This is a schematic diagram of the structure of a bulk acoustic resonator device in another embodiment of this utility model;

[0036] Figure 9 This is a schematic diagram of the structure of a bulk acoustic resonator device in another embodiment of this utility model;

[0037] Figure 10 This is a schematic diagram of the structure of a bulk acoustic resonator device in another embodiment of this utility model;

[0038] Figure 11 This is a schematic diagram of the structure of a bulk acoustic resonator device in another embodiment of this utility model;

[0039] Figure 12 This is a schematic diagram of the structure of a bulk acoustic resonator in another embodiment of the present invention. Detailed Implementation

[0040] As described in the background section, bulk acoustic resonator devices still have many problems. These will be explained in detail below with reference to the accompanying drawings.

[0041] Figure 1 This is a schematic diagram of a bulk acoustic resonator.

[0042] Please refer to Figure 1 A bulk acoustic wave resonant device includes: a substrate 100 having a cavity 101 within it, with the cavity 101 exposed on the surface of the substrate 100; a lower electrode layer 102 on the substrate 100, covering the cavity 101; a piezoelectric layer 103 on the lower electrode layer 102; an upper electrode layer 104 on the piezoelectric layer 103, the projections of the upper electrode layer 104 and the lower electrode layer 102 toward the substrate 100 having an overlapping region, the overlapping region constituting a resonant region; a raised edge structure 105 on the piezoelectric layer 103 surrounding the upper electrode layer 104; and a reflection region located laterally outside the resonant region, surrounding the resonant region, the reflection region including the raised edge structure 105, the acoustic impedance of the reflection region being mismatched with the acoustic impedance of the resonant region, i.e., a large difference in acoustic impedance.

[0043] There are two main factors that reduce the quality factor at the parallel resonant point of the bulk acoustic resonator: (1) the sound wave propagates laterally from the resonant region to the region outside the resonant region, causing acoustic energy leakage; (2) the higher-order transverse parasitic mode is coupled with the first-order transverse mode.

[0044] In the above embodiments, the reflection zone formed by the protruding edge structure 105 on the lateral outer side of the resonant region can suppress the influence of the first factor, reflecting the first-order lateral mode back to the resonant region and preventing most of the acoustic energy leakage, but it cannot improve the second influencing factor. The protruding edge structure 105 reflects the first-order lateral mode while also reflecting higher-order lateral parasitic modes.

[0045] Based on this, the present invention provides a bulk acoustic resonator, wherein the first dielectric layer is located between the first attenuation section, the first confinement section, and the piezoelectric layer. Therefore, the first attenuation region and the first confinement region corresponding to the first dielectric layer will not excite significant parasitic resonances. Since the acoustic impedance of the first attenuation region is matched (e.g., equal to or less than) the acoustic impedance of the resonant region, while the acoustic impedance of the first confinement region is mismatched with that of the first attenuation region, i.e., the impedance difference is large, the first-order transverse mode can pass through the first attenuation region unaffected, and then be fully reflected back to the resonant region in the first confinement region, thereby significantly reducing transverse leakage. However, higher-order transverse parasitic modes entering the first attenuation region will undergo attenuation. By reasonably setting the width of the first attenuation region, the higher-order transverse parasitic modes can be fully attenuated within the first attenuation region, with only a small number or even no higher-order transverse parasitic modes entering the first confinement region, thereby preventing the higher-order transverse parasitic modes from reflecting back to the resonant region and coupling with the first-order transverse mode. This can improve the parallel impedance value and the corresponding Q value.

[0046] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0047] Figure 2 This is a schematic diagram of the structure of a bulk acoustic resonator device in one embodiment of this utility model; Figure 3 This is a comparison chart of the real part amplitude of impedance and the quality factor as a function of frequency between the present invention and existing technologies.

[0048] Please refer to Figure 2A bulk acoustic resonator includes: an acoustic reflection layer; a first electrode layer 207, the first electrode layer 207 including 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; and a piezoelectric layer 204, the piezoelectric layer 204 including a first side 2041 and a second side 2042 opposite to the first side 2041, the first electrode layer 207 being located on the first side 2041. An acoustic reflection layer is located on the second side 2042; a second electrode layer 203 is located on the second side 2042, corresponding to the first electrode layer 207, and includes a second resonant portion 203a, which corresponds to the first resonant portion 207a; a resonant region 208 includes the first resonant portion 207a, the second resonant portion 203a, and the piezoelectric layer 204 located between the first resonant portion 207a and the second resonant portion 203a; and a first dielectric layer 205 is located on the first side 2042. 041, the first dielectric layer 205 includes a first dielectric portion 205a and a second dielectric portion 205b, the first dielectric portion 205a being located between a portion of the first attenuation portion 207b and the piezoelectric layer 204, and the second dielectric portion 205b being located between the first limiting portion 207c and the piezoelectric layer 204; a first load layer 206, the first load layer 206 being located on the first side 2041, the first load layer 206 corresponding to the first limiting portion 207c and the second dielectric portion 205b; a first attenuation region 209 located outside the resonant region 208, used for attenuating sound waves, the first attenuation region 209 surrounding the resonant region 208. 08, the first attenuation region 209 includes a first attenuation portion 207b and a first dielectric portion 205a; a first restriction region 210 located outside the first attenuation region 209 is used to reflect sound waves, the first restriction region 210 surrounds the first attenuation region 209, the first restriction region 210 includes a first restriction portion 207c, a second dielectric portion 205b and a first load layer 206; wherein, there is a first spacing dimension d1 between the edge of the first load layer 206 near the resonant region 208 and the edge of the first dielectric portion 205a near the resonant region 208, the first spacing dimension d1 being in the range of 0.5 micrometers to 5 micrometers.

[0049] The first dielectric layer 205 is located between the first attenuation portion 207b, the first restriction portion 207c and the piezoelectric layer 204. Therefore, the first attenuation region 209 and the first restriction region 210 corresponding to the first dielectric layer 205 will not excite obvious parasitic resonances. Because the acoustic impedance of the first attenuation region 209 matches (e.g., equal to or less than) the acoustic impedance of the resonant region 208, while the acoustic impedance of the first confinement region 210 is mismatched with that of the first attenuation region 209 (i.e., the impedance difference is large), the first-order transverse mode can pass through the first attenuation region 209 unaffected, and then be fully reflected back to the resonant region 208 in the first confinement region 210, thereby significantly reducing transverse leakage. However, higher-order transverse parasitic modes entering the first attenuation region 209 will experience attenuation. By reasonably setting the width of the first attenuation region 209, the higher-order transverse parasitic modes can be fully attenuated within the first attenuation region 209, with only a small number or even no higher-order transverse parasitic modes entering the first confinement region 210, thereby preventing the higher-order transverse parasitic modes from reflecting back to the resonant region 208 and coupling with the first-order transverse mode. This can improve the parallel impedance value and the corresponding Q value. Furthermore, the first spacing dimension d1 ranges from 0.5 micrometers to 5 micrometers. When the first spacing dimension d1 is less than 0.5 micrometers, the spacing dimension is smaller than half the wavelength of the transmitted wave, the attenuation effect is not obvious, and the small spacing dimension makes it difficult to achieve the alignment accuracy of photolithography. When the first spacing dimension d1 is greater than 5 micrometers, the spacing dimension is large, resulting in a large parasitic capacitance, which can easily cause the electromechanical coupling coefficient of the resonator to decrease.

[0050] It should be noted that, in this embodiment, the first spacing dimension d1 between the edge of the first load layer 206 near the resonant region 208 and the edge of the first dielectric portion 205a near the resonant region 208 is a positive value, that is, it means that the edge of the first load layer 206 near the resonant region 208 is located outside the edge of the first dielectric portion 205a near the resonant region 208.

[0051] Please refer to Figure 3In the figure, the horizontal axis represents frequency, the left vertical axis represents the amplitude of the real part of the impedance, and the right vertical axis represents the quality factor (BodeQ) as a function of frequency. The solid triangular line in the figure represents the amplitude of the real part of the impedance in the bulk acoustic wave resonator of this invention, while the dashed triangular line represents the amplitude of the real part of the impedance in a prior art bulk acoustic wave resonator. 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 of this invention, and the dashed line represents the BodeQ curve of a prior art bulk acoustic wave resonator. The point with the maximum vertical value is the Qmax value. The BodeQ of the bulk acoustic wave resonator corresponding to the parallel resonant frequency is the parallel resonant Q value of the bulk acoustic wave resonator. It can be seen from the figure that the Qmax value and parallel resonant Q value of the bulk acoustic wave resonator provided by this embodiment are significantly better than those of the prior art.

[0052] In this embodiment, the acoustic 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.

[0053] In this embodiment, the bulk acoustic resonator further includes a substrate 200, and the cavity 201 is embedded in the substrate 200.

[0054] In this embodiment, the first load layer 206 corresponds to the cavity 201.

[0055] In this embodiment, the second electrode layer 203 further includes a second non-resonant portion 203b, which is located outside the second resonant portion 203a and surrounds the second resonant portion 203a.

[0056] In this embodiment, the second non-resonant part 203b corresponds to the first attenuation part 207b and the first limiting part 207c.

[0057] In this embodiment, the first attenuation region 209 further includes a second non-resonant region 203b corresponding to the first attenuation region 207b.

[0058] In this embodiment, the first restriction area 210 further includes a second non-resonant portion 203b corresponding to the first restriction portion 207c.

[0059] It should be noted that the first attenuation part 207b includes a first sub-part 207b1 and a second sub-part 207b2, the second sub-part 207b2 being located outside the first sub-part 207b1; the angle between the first sub-part 207b1 and the first resonant part 207a is greater than or equal to 90° and less than 180°; the angle between the first sub-part 207b1 and the second sub-part 207b2 is greater than or equal to 90° and less than 180°.

[0060] Please continue to refer to this. Figure 2 In this embodiment, the angle between the first sub-part 207b1 and the first resonant part 207a is 90°, and the angle between the first sub-part 207b1 and the second sub-part 207b2 is 90°.

[0061] In this embodiment, the first dielectric portion 205a is located between the second sub-portion 207b2 and the piezoelectric layer 204; the first dielectric portion 205a is located outside the first sub-portion 207b1.

[0062] In this embodiment, the first load layer 206 is located between the second medium portion 205b and the first limiting portion 207c.

[0063] In other embodiments, the first limiting portion 207c may also be located between the second medium portion 205b and the first load layer 206.

[0064] It should be noted that, in this embodiment, there is a second spacing dimension d2 between the outer edge of the first electrode layer 207 (i.e., the edge of the first electrode layer 207 away from the resonant region 208) and the outer edge of the first load layer 206 (i.e., the edge of the first load layer 206 away from the resonant region 208). The range of the second spacing dimension d2 includes -2s to 2s, where s represents the thickness of the stacked structure of the resonant region 208. A negative second spacing dimension d2 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 second spacing dimension d2 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 second spacing dimension d2 between the outer edge of the first electrode layer 207 and the outer edge of the first load layer 206 is 0 (i.e., flush).

[0065] The materials of the first electrode layer 207 and the second electrode layer 203 include: molybdenum, tungsten, copper, platinum, rhenium, osmium, iridium, tantalum, gold or hafnium.

[0066] In this embodiment, the material of the first electrode layer 207 is molybdenum; the thickness of the first electrode layer 207 ranges from 200 nanometers to 350 nanometers.

[0067] In this embodiment, the material of the second electrode layer 203 is molybdenum; the thickness of the second electrode layer 203 ranges from 200 nanometers to 350 nanometers.

[0068] The materials of the piezoelectric layer 204 include: lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate, aluminum nitride, aluminum nitride alloy, gallium nitride, or zinc oxide.

[0069] In this embodiment, the material of the piezoelectric layer 204 includes aluminum nitride or scandium-doped aluminum nitride; the thickness of the piezoelectric layer 204 ranges from 900 nanometers to 1100 nanometers.

[0070] In this embodiment, the material of the first load layer 206 is a metal, including molybdenum, tungsten, platinum, palladium, gold, chromium, tantalum, or iridium. Specifically, platinum can be used. The material density of the first load layer 206 is greater than that of the first electrode layer 207 and the second electrode layer 203, which increases the overall mass of the first confinement region 210, thereby increasing the difference between the acoustic impedance of the first confinement region 210 and the acoustic impedance of the resonant region 208, thus forming an acoustic impedance mismatch.

[0071] In this embodiment, the thickness of the first load layer 206 ranges from 80 nanometers to 120 nanometers.

[0072] The material of the first dielectric layer 205 includes: silicon dioxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, or air.

[0073] In this embodiment, the material of the first dielectric layer 205 is silicon dioxide; the thickness of the first dielectric layer 205 ranges from 80 nanometers to 120 nanometers.

[0074] In this embodiment, the operating frequency range of the bulk acoustic resonator is 2300MHz~2500MHz.

[0075] Figure 4 This is a schematic diagram of the structure of a bulk acoustic resonator in another embodiment of the present invention.

[0076] Please refer to Figure 4 This embodiment is based on the above embodiment ( Figure 2 Based on the above embodiments, the bulk acoustic resonator will continue to be described. The rest is the same as the above embodiments, except that: the angle between the first sub-part 207b1 and the first resonator 207a can be greater than 90° and less than 180°, the angle between the first sub-part 207b1 and the second sub-part 207b2 is greater than 90° and less than 180°; the first dielectric part 205a is also located between part of the first sub-part 207b1 and the piezoelectric layer 204.

[0077] Figure 5 This is a schematic diagram of the structure of a bulk acoustic resonator in another embodiment of the present invention.

[0078] Please refer to Figure 5This embodiment is based on the above embodiment ( Figure 2 Based on the above embodiments, the method for forming the bulk acoustic resonator will be further described. The rest is the same as the above embodiments, except that the acoustic reflection layer includes the Bragg reflection layer 301 located on the substrate 300.

[0079] Figure 6 This is a schematic diagram of the structure of a bulk acoustic resonator in another embodiment of the present invention.

[0080] Please refer to Figure 6 This embodiment is based on the above embodiment ( Figure 2 Based on the above embodiments, the method for forming the bulk acoustic resonator will be further described. The rest is the same as the above embodiments, except that the first limiting part 207c is located between the second dielectric part 205b and the first load layer 206.

[0081] Figure 7 This is a schematic diagram of the structure of a bulk acoustic resonator in another embodiment of the present invention.

[0082] Please refer to Figure 7 This embodiment is based on the above embodiment ( Figure 2 Based on the above embodiments, the method for forming the bulk acoustic resonator will continue to be described. The rest is the same as the above embodiments, except that: the first electrode layer 207 further 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 further 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 resonator further includes: a second attenuation region 211 located outside the first limiting region 210, used to attenuate unreflected high-order transverse acoustic waves, the second attenuation region 211 surrounds the first limiting region 210, and the second attenuation region 211 includes the second attenuation portion 207d and the third dielectric portion 205c.

[0083] In this embodiment, the second spacing dimension d2 between the edge of the first load layer 206 away from the resonant region 208 and the edge of the first electrode layer 207 away from the resonant region 208 (i.e. the edge of the second attenuation portion 207d away from the resonant region 208) is a positive value, and the range of the second spacing dimension d2 is 0.5 micrometers to 3 micrometers.

[0084] In this embodiment, the first load layer 206, the second attenuation portion 207d, and the third medium portion 205c correspond to the cavity 201.

[0085] Figure 8This is a schematic diagram of the structure of a bulk acoustic resonator in another embodiment of the present invention.

[0086] Please refer to Figure 8 A bulk acoustic resonator includes: an acoustic reflection layer; a first electrode layer 410, the first electrode layer 410 including a first resonant portion 410a, a first attenuation portion 410b located outside the first resonant portion 410a, the first attenuation portion 410b surrounding the first resonant portion 410a, and a first limiting portion 410c located outside the first attenuation portion 410b, the first limiting portion 410c surrounding the first attenuation portion 410b; and a piezoelectric layer 401, the piezoelectric layer 401 including a first side 4011 and a second side 4012 opposite to the first side 4011, the first electrode layer 410 being located on the first side 4011. An acoustic reflection layer is located on the second side 4012; a second electrode layer 402 is located on the second side 4012, and the second electrode layer 402 corresponds to the first electrode layer 410. The second electrode layer 402 includes a second resonant portion 402a, which corresponds to the first resonant portion 410a; a resonant region 411 includes the first resonant portion 410a, the second resonant portion 402a, and the piezoelectric layer 401 located between the first resonant portion 410a and the second resonant portion 402a; and a first dielectric layer 408 is located on the first side 4012. 011, the first dielectric layer 408 includes a first dielectric portion 408a and a second dielectric portion 408b, the first dielectric portion 408a being located between a portion of the first attenuation portion 410b and the piezoelectric layer 401, and the second dielectric portion 408b being located between the first limiting portion 410c and the piezoelectric layer 401; a first load layer 409, the first load layer 409 being located on the first side 4011, the first load layer 409 corresponding to the first limiting portion 410c and the second dielectric portion 408b; a first attenuation region 412 located outside the resonant region 411, used for attenuating sound waves, the first attenuation region 412 surrounding the resonant region 4011. 11. The first attenuation region 412 includes a first attenuation portion 410b and a first dielectric portion 408a; a first restriction region 413 located outside the first attenuation region 412 is used to reflect sound waves, the first restriction region 413 surrounds the first attenuation region 412, the first restriction region 413 includes a first restriction portion 410c, a second dielectric portion 408b and a first load layer 409; wherein, there is a first spacing dimension d1 between the edge of the first load layer 409 near the resonant region 411 and the edge of the first dielectric portion 408a near the resonant region 411, the first spacing dimension d1 being in the range of 0.5 micrometers to 5 micrometers.

[0087] The first dielectric layer 408 is located between the first attenuation portion 410b, the first restriction portion 410c and the piezoelectric layer 401. Therefore, the first attenuation region 412 and the first restriction region 413 corresponding to the first dielectric layer 408 will not excite obvious parasitic resonances. Because the acoustic impedance of the first attenuation region 412 matches (e.g., equal to or less than) the acoustic impedance of the resonant region 411, while the acoustic impedance of the first confinement region 413 is mismatched with that of the first attenuation region 412 (i.e., the impedance difference is large), the first-order transverse mode can pass through the first attenuation region 412 unaffected, and then be fully reflected back to the resonant region 411 in the first confinement region 413, thereby significantly reducing transverse leakage. However, higher-order transverse parasitic modes entering the first attenuation region 412 will experience attenuation. By reasonably setting the width of the first attenuation region 412, the higher-order transverse parasitic modes can be fully attenuated within the first attenuation region 412, with only a small number or even no higher-order transverse parasitic modes entering the first confinement region 413, thereby preventing the higher-order transverse parasitic modes from reflecting back to the resonant region 411 and coupling with the first-order transverse mode. This can improve the parallel impedance value and the corresponding Q value. Furthermore, the first spacing dimension d1 ranges from 0.5 micrometers to 5 micrometers. When the first spacing dimension d1 is less than 0.5 micrometers, the spacing dimension is smaller than half the wavelength of the transmitted wave, the attenuation effect is not obvious, and the small spacing dimension makes it difficult to achieve the alignment accuracy of photolithography. When the first spacing dimension d1 is greater than 5 micrometers, the spacing dimension is large, resulting in a large parasitic capacitance, which can easily cause the electromechanical coupling coefficient of the resonator to decrease.

[0088] It should be noted that, in this embodiment, the first spacing dimension d1 between the edge of the first load layer 409 near the resonant region 411 and the edge of the first dielectric portion 408a near the resonant region 411 is a positive value, that is, it means that the edge of the first load layer 409 near the resonant region 411 is located outside the edge of the first dielectric portion 408a near the resonant region 411.

[0089] In this embodiment, the second electrode layer 402 further includes a third non-resonant portion 402b, which is located outside the second resonant portion 402a and surrounds the second resonant portion 402a. The third non-resonant portion 402b corresponds to the first attenuation portion 410b and the first limiting portion 410c.

[0090] In this embodiment, the first attenuation region 412 further includes the third non-resonant portion 402b corresponding to the first attenuation portion 410b, and the first restriction region 413 further includes the third non-resonant portion 402b corresponding to the first restriction portion 410c.

[0091] In this embodiment, the bulk acoustic wave resonator further includes: an intermediate layer 404 located on the second side 4012; a device substrate 406 located on the second side 4012; a first sub-bonding layer 405 located on the second side 4012; and a second sub-bonding layer 407 located on the second side 4012, wherein the first sub-bonding layer 405 and the second sub-bonding layer 407 are bonded together; the first sub-bonding layer 405 and the second sub-bonding layer 407 are located between the intermediate layer 404 and the device substrate 406, wherein the first sub-bonding layer 405 is located between the second sub-bonding layer 407 and the intermediate layer 407, and the second sub-bonding layer 407 is located between the first sub-bonding layer 405 and the device substrate 406.

[0092] It should be noted that the first attenuation part 410b includes a first sub-part 410b1 and a second sub-part 410b2, the second sub-part 410b2 being located outside the first sub-part 410b1; the angle between the first sub-part 410b1 and the first resonant part 410a is greater than or equal to 90° and less than 180°; the angle between the first sub-part 410b1 and the second sub-part 410b2 is greater than or equal to 90° and less than 180°.

[0093] In this embodiment, the angle between the first sub-part 410b1 and the first resonant part 410a is 90°, and the angle between the first sub-part 410b1 and the second sub-part 410b2 is 90°.

[0094] 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.

[0095] In other embodiments, the angle between the first sub-part 410b1 and the first resonant part 410a is greater than 90° and less than 180°, and the angle between the first sub-part 410b1 and the second sub-part 410b2 is greater than 90° and less than 180°; the first dielectric part 408a is also located between a portion of the first sub-part 410b1 and the piezoelectric layer 401.

[0096] In this embodiment, the first load layer 409 is located between the second medium portion 408b and the first limiting portion 410c.

[0097] In other embodiments, the first limiting portion 410c may also be located between the second medium portion 408b and the first load layer 409.

[0098] It should be noted that there is a second spacing dimension d2 between the outer edge of the first electrode layer 410 and the outer edge of the first load layer 409. The range of the second spacing dimension d2 includes -2s to 2s, where s represents the thickness of the stacked structure of the resonant region 411. A negative second spacing dimension d2 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 second spacing dimension d2 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 second spacing dimension d2 between the outer edge of the first electrode layer 410 and the outer edge of the first load layer 409 is 0 (i.e., flush).

[0099] In this embodiment, the acoustic reflection layer includes a cavity 414, which is located on the second side 4012 and embedded in the intermediate layer 404. The second electrode layer 402 is located between the cavity 414 and the piezoelectric layer 401, and the second electrode layer 402 is located within the cavity 414.

[0100] The materials of the first electrode layer 410 and the second electrode layer 402 include: molybdenum, tungsten, copper, platinum, rhenium, osmium, iridium, tantalum, gold or hafnium.

[0101] In this embodiment, the material of the first electrode layer 410 is molybdenum; the thickness of the first electrode layer 410 ranges from 200 nanometers to 350 nanometers.

[0102] In this embodiment, the material of the second electrode layer 402 is molybdenum; the thickness of the second electrode layer 402 ranges from 200 nanometers to 350 nanometers.

[0103] The materials of the piezoelectric layer 401 include: lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate, aluminum nitride, aluminum nitride alloy, gallium nitride, or zinc oxide.

[0104] In this embodiment, the material of the piezoelectric layer 401 includes aluminum nitride or scandium-doped aluminum nitride; the thickness of the piezoelectric layer 401 ranges from 900 nanometers to 1100 nanometers.

[0105] In this embodiment, the material of the first load layer 409 is a metal, including molybdenum, tungsten, platinum, palladium, gold, chromium, tantalum, or iridium. Specifically, platinum can be used. The material density of the first load layer 409 is greater than that of the first electrode layer 410 and the second electrode layer 402, which increases the overall mass of the first confinement region 413, thereby increasing the difference between the acoustic impedance of the first confinement region 413 and the acoustic impedance of the resonant region 411, thus forming an acoustic impedance mismatch.

[0106] In this embodiment, the thickness of the first load layer 409 ranges from 80 nanometers to 120 nanometers.

[0107] The material of the first dielectric layer 408 includes: silicon dioxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, or air.

[0108] In this embodiment, the material of the first dielectric layer 408 is silicon dioxide; the thickness of the first dielectric layer 408 ranges from 80 nanometers to 120 nanometers.

[0109] In this embodiment, the operating frequency range of the bulk acoustic resonator is 2300MHz~2500MHz.

[0110] Figure 9 This is a schematic diagram of the structure of a bulk acoustic resonator in another embodiment of the present invention.

[0111] Please refer to Figure 9 This embodiment is based on the above embodiment ( Figure 8 Based on the above embodiments, the method for forming the bulk acoustic resonator will continue to be described. The rest is the same as the above embodiments, except that: the first electrode layer 410 further 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 further includes a third dielectric portion 408c, and the third dielectric portion 408c is located between the piezoelectric layer 401 and the second attenuation portion 410d; the bulk acoustic resonator further includes: a second attenuation region 415 located outside the first limiting region 413, used to attenuate unreflected high-order transverse acoustic waves, the second attenuation region 415 surrounds the first limiting region 413, and the second attenuation region 415 includes the second attenuation portion 410d and the third dielectric portion 408c.

[0112] It should be noted that the second spacing dimension d2 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.

[0113] In this embodiment, the second spacing dimension d2 between the outer edge of the first electrode layer 410 and the outer edge of the first load layer 409 is a positive value. Specifically, the second spacing dimension d2 is between the edge of the first load layer 409 away from the resonant region 411 (i.e., the outer edge of the first load layer 409) and the edge of the second attenuation portion 410d away from the resonant region 411 (i.e., the outer edge of the first electrode layer 410), and the second spacing dimension d2 ranges from 0.5 micrometers to 3 micrometers.

[0114] In this embodiment, the second attenuation region 415 further includes the third non-resonant region 402b corresponding to the second attenuation region 410d.

[0115] Figure 10 This is a schematic diagram of the structure of a bulk acoustic resonator in another embodiment of the present invention.

[0116] Please refer to Figure 10A bulk acoustic resonator includes: an acoustic reflection layer; a first electrode layer 504, the first electrode layer 504 including a first resonant portion 504a, a first attenuation portion 504b located outside the first resonant portion 504a, the first attenuation portion 504b surrounding the first resonant portion 504a, and a first limiting portion 504c located outside the first attenuation portion 504b, the first limiting portion 504c surrounding the first attenuation portion 504b; a piezoelectric layer 501, the piezoelectric layer 501 including a first side 5011 and a second side 5012 opposite to the first side 5011, the first electrode layer 504 being located on the first side 5011, and the first electrode layer 504 being located on the first side 5011. An acoustic reflection layer is located on the first side 5011; a second electrode layer 510 is located on the second side 5012, corresponding to the first electrode layer 504, and includes a second resonant portion 510a, corresponding to the first resonant portion 504a; a resonant region 511 includes the first resonant portion 504a, the second resonant portion 510a, and the piezoelectric layer 501 located between the first resonant portion 504a and the second resonant portion 510a; and a first dielectric layer 502 is located on the first side 5012. 011, the first dielectric layer 502 includes a first dielectric portion 502a and a second dielectric portion 502b, the first dielectric portion 502a being located between a portion of the first attenuation portion 504b and the piezoelectric layer 501, and the second dielectric portion 502b being located between the first limiting portion 504c and the piezoelectric layer 501; a first load layer 503, the first load layer 503 being located on the first side 5011, the first load layer 503 corresponding to the first limiting portion 504c and the second dielectric portion 502b; a first attenuation region 512 located outside the resonant region 511, used for attenuating sound waves, the first attenuation region 512 surrounding the resonant region 5011. 11. The first attenuation region 512 includes a first attenuation portion 504b and a first dielectric portion 502a; a first restriction region 513 located outside the first attenuation region 512 is used to reflect sound waves, the first restriction region 513 surrounds the first attenuation region 512, and the first restriction region 513 includes a first restriction portion 504c, a second dielectric portion 502b and a first load layer 503; wherein, there is a first spacing dimension d1 between the edge of the first load layer 503 near the resonant region 511 and the edge of the first dielectric portion 502a near the resonant region 511, the first spacing dimension d1 being in the range of 0.5 micrometers to 5 micrometers.

[0117] The first dielectric layer 502 is located between the first attenuation portion 504b, the first restriction portion 504c and the piezoelectric layer 501. Therefore, the first attenuation region 512 and the first restriction region 513 corresponding to the first dielectric layer 502 will not excite obvious parasitic resonances. Because the acoustic impedance of the first attenuation region 512 matches (e.g., equal to or less than) the acoustic impedance of the resonant region 511, while the acoustic impedance of the first confinement region 513 is mismatched with that of the first attenuation region 512 (i.e., the impedance difference is large), the first-order transverse mode can pass through the first attenuation region 512 unaffected, and then be fully reflected back to the resonant region 511 in the first confinement region 513, thereby significantly reducing transverse leakage. However, higher-order transverse parasitic modes entering the first attenuation region 512 will experience attenuation. By reasonably setting the width of the first attenuation region 512, the higher-order transverse parasitic modes can be fully attenuated within the first attenuation region 512, with only a small number or even no higher-order transverse parasitic modes entering the first confinement region 513, thereby preventing the higher-order transverse parasitic modes from reflecting back to the resonant region 511 and coupling with the first-order transverse mode. This can improve the parallel impedance value and the corresponding Q value. Furthermore, the first spacing dimension d1 ranges from 0.5 micrometers to 5 micrometers. When the first spacing dimension d1 is less than 0.5 micrometers, the spacing dimension is smaller than half the wavelength of the transmitted wave, the attenuation effect is not obvious, and the small spacing dimension makes it difficult to achieve the alignment accuracy of photolithography. When the first spacing dimension d1 is greater than 5 micrometers, the spacing dimension is large, resulting in a large parasitic capacitance, which can easily cause the electromechanical coupling coefficient of the resonator to decrease.

[0118] It should be noted that, in this embodiment, the first spacing dimension d1 between the edge of the first load layer 503 near the resonant region 511 and the edge of the first dielectric portion 502a near the resonant region 511 is a positive value, that is, it means that the edge of the first load layer 503 near the resonant region 511 is located outside the edge of the first dielectric portion 502a near the resonant region 511.

[0119] In this embodiment, the first load layer 503 is located on one side of the second medium portion 502b and is in contact with the second medium portion 502b.

[0120] In this embodiment, the first electrode layer 504 is located on the first side 5011, and the first resonant part 504a is in contact with the piezoelectric layer 501, that is, the first electrode layer 504 is the lower electrode layer of the bulk acoustic wave resonator.

[0121] In this embodiment, the first load layer 503 is located between the second medium portion 502b and the first limiting portion 504c.

[0122] 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 504c may also be located between the first load layer 503 and the second dielectric portion 502b.

[0123] It should be noted that the first attenuation part 504b includes a first sub-part 504b1 and a second sub-part 504b2, the second sub-part 504b2 being located outside the first sub-part 504b1; the angle between the first sub-part 504b1 and the first resonant part 504a is greater than or equal to 90° and less than 180°; the angle between the first sub-part 504b1 and the second sub-part 504b2 is greater than or equal to 90° and less than 180°.

[0124] In this embodiment, the angle between the first sub-part 504b1 and the first resonant part 504a is 90°, and the angle between the first sub-part 504b1 and the second sub-part 504b2 is 90°.

[0125] 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.

[0126] In other embodiments, the angle between the first sub-part 504b1 and the first resonant part 504a is greater than 90° and less than 180°, and the angle between the first sub-part 504b1 and the second sub-part 504b2 is greater than 90° and less than 180°; the first dielectric part 502a is also located between a portion of the first sub-part 504b1 and the piezoelectric layer 501.

[0127] In this embodiment, the bulk acoustic wave resonator further includes: an intermediate layer 506 located on the first side 5011; a device substrate 508 located on the first side 5011; a first sub-bonding layer 507 located on the first side 5011; and a second sub-bonding layer 509 located on the first side 5011, wherein the first sub-bonding layer 507 and the second sub-bonding layer 509 are bonded together; the first sub-bonding layer 507 and the second sub-bonding layer 509 are located between the intermediate layer 506 and the device substrate 508, wherein the first sub-bonding layer 507 is located between the second sub-bonding layer 509 and the intermediate layer 506, and the second sub-bonding layer 509 is located between the first sub-bonding layer 507 and the device substrate 508.

[0128] In this embodiment, the second electrode layer 510 is located on the second side 5012 and is in contact with the piezoelectric layer 501, that is, the second electrode layer 510 is the upper electrode layer of the bulk acoustic resonator.

[0129] In this embodiment, the second electrode layer 510 further includes a fourth non-resonant portion 510b, which 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.

[0130] In this embodiment, the first attenuation region 512 further includes the fourth non-resonant portion 510b corresponding to the first attenuation portion 504b, and the first restriction region 513 further includes the fourth non-resonant portion 510b corresponding to the first restriction portion 504c.

[0131] It should be noted that there is a second spacing dimension d2 between the outer edge of the first electrode layer 504 and the outer edge of the first load layer 503. The range of the second spacing dimension d2 includes -2s to 2s, where s represents the thickness of the stacked structure of the resonant region 511. A negative second spacing dimension d2 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 second spacing dimension d2 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 second spacing dimension d2 between the outer edge of the first electrode layer 504 and the outer edge of the first load layer 503 is 0 (i.e., flush).

[0132] In this embodiment, the acoustic reflection layer includes a cavity 514, which is embedded in the intermediate layer 506. The cavity 514 is located on the first side 5011, and the first electrode layer 504, the first dielectric layer 502, and the first load layer 503 are located in the cavity 514.

[0133] The materials of the first electrode layer 504 and the second electrode layer 510 include: molybdenum, tungsten, copper, platinum, rhenium, osmium, iridium, tantalum, gold or hafnium.

[0134] In this embodiment, the material of the first electrode layer 504 is molybdenum; the thickness of the first electrode layer 504 ranges from 200 nanometers to 350 nanometers.

[0135] In this embodiment, the material of the second electrode layer 510 is molybdenum; the thickness of the second electrode layer 510 ranges from 200 nanometers to 350 nanometers.

[0136] The materials of the piezoelectric layer 501 include: lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate, aluminum nitride, aluminum nitride alloy, gallium nitride, or zinc oxide.

[0137] In this embodiment, the material of the piezoelectric layer 501 includes aluminum nitride or scandium-doped aluminum nitride; the thickness of the piezoelectric layer 501 ranges from 900 nanometers to 1100 nanometers.

[0138] In this embodiment, the material of the first load layer 503 is a metal, including: molybdenum, tungsten, platinum, palladium, gold, chromium, tantalum, or iridium. Specifically, platinum can be used. The material density of the first load layer 503 is greater than that of the first electrode layer 504 and the second electrode layer 510, which increases the overall mass of the first confinement region 513, thereby increasing the difference between the acoustic impedance of the first confinement region 513 and the acoustic impedance of the resonant region 511, thus forming an acoustic impedance mismatch.

[0139] In this embodiment, the thickness of the first load layer 503 ranges from 80 nanometers to 120 nanometers.

[0140] The material of the first dielectric layer 502 includes: silicon dioxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, or air.

[0141] In this embodiment, the material of the first dielectric layer 502 is silicon dioxide; the thickness of the first dielectric layer 502 ranges from 80 nanometers to 120 nanometers.

[0142] In this embodiment, the operating frequency range of the bulk acoustic resonator is 2300MHz~2500MHz.

[0143] Figure 11 This is a schematic diagram of the structure of a bulk acoustic resonator in another embodiment of the present invention.

[0144] This embodiment is based on the above embodiment ( Figure 10 Based on the above embodiments, the method for forming the bulk acoustic resonator will continue to be described. The rest is the same as the above embodiments, except that: the first electrode layer 504 further 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 further 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 resonator further includes: a second attenuation region 515 located outside the first limiting region 513, used to attenuate unreflected high-order transverse acoustic waves, the second attenuation region 515 surrounds the first limiting region 513, and the second attenuation region 515 includes the second attenuation portion 504d and the third dielectric portion 502c.

[0145] It should be noted that the second spacing dimension d2 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.

[0146] In this embodiment, the second spacing dimension d2 between the outer edge of the first electrode layer 504 and the outer edge of the first load layer 503 is a positive value. Specifically, there is a second spacing dimension d2 between the edge of the first load layer 503 away from the resonant region 511 (i.e., the outer edge of the first load layer 503) and the edge of the second attenuation portion 504d away from the resonant region 511 (i.e., the outer edge of the first electrode layer 504), and the second spacing dimension d2 ranges from 0.5 micrometers to 3 micrometers.

[0147] Figure 12 This is a schematic diagram of the structure of a bulk acoustic resonator in another embodiment of the present invention.

[0148] This embodiment is based on the above embodiment ( Figure 10 Based on the above, the method for forming the bulk acoustic resonator will continue to be described. The rest is the same as the above embodiment, except that: the second electrode layer 510 further includes a third attenuation part 510c located outside the second resonant part 510a, the third attenuation part 510c surrounding the second resonant part 510a, and a second limiting part 510d located outside the third attenuation part 510c, the second limiting part 510d surrounding the third attenuation part 510c.

[0149] In this embodiment, the bulk acoustic resonator further includes: a second dielectric layer 600 located on the second side 5012, the second dielectric layer 600 including a fourth dielectric portion 600a and a fifth dielectric portion 600b; and a second load layer 601 located on the second side 5012.

[0150] It should be noted that, in this embodiment, the second electrode layer 510 does not have the following... Figure 10 The fourth non-resonant part 510b as described in the relevant description.

[0151] In this embodiment, the fourth dielectric portion 600a is located between a portion 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.

[0152] In this embodiment, the division of the remaining region of the second electrode layer 510 and its positional relationship with other structures can be specifically referred to... Figure 10As mentioned in the relevant explanations, they will not be repeated here.

[0153] In this embodiment, the first attenuation region 512 further includes a third attenuation portion 510c and a fourth dielectric portion 600a; the first restriction region 513 further includes a second restriction portion 510d, a fifth dielectric portion 600b and a second load layer 601.

[0154] In other embodiments, the first electrode layer 504 may also employ, for example... Figure 11 The structure shown, the second electrode layer 510 can also be adopted as... Figure 9 The first electrode layer 410 structure shown is illustrated.

[0155] Accordingly, the present invention also provides a filtering device, including the bulk acoustic resonator as described in any of the above embodiments.

[0156] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A bulk acoustic resonant device, characterized in that, include: Acoustic reflector layer; A first electrode layer, the first electrode layer including a first resonant portion, a first attenuation portion located outside the first resonant portion, the first attenuation portion surrounding the first resonant 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 including 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 is located on the second side and corresponds to the first electrode layer. The second electrode layer includes a second resonant portion, which corresponds to the first resonant portion. The resonant region includes a first resonant portion, a second resonant portion, and the piezoelectric layer located between the first resonant portion and the second resonant portion; A first dielectric layer is located on the first side. The first dielectric layer includes a first dielectric portion and a second dielectric portion. The first dielectric portion is located between a portion of the first attenuation portion and the piezoelectric layer, and the second dielectric portion is located between the first limiting portion and the piezoelectric layer. A first load layer is located on the first side, and the first load layer corresponds to the first limiting part and the second medium part; A first attenuation region located outside the resonant region is used to attenuate sound waves. The first attenuation region surrounds the resonant region and includes a first attenuation part and a first dielectric part. A first confinement region located outside the first attenuation region is used to reflect sound waves. The first confinement region surrounds the first attenuation region and includes a first confinement portion, a second dielectric portion, and a first load layer; wherein... The first load layer has a first spacing dimension between its edge near the resonant region and the edge of the first dielectric portion near the resonant region, the first spacing dimension ranging from 0.5 micrometers to 5 micrometers.

2. The bulk acoustic resonator as described in claim 1, characterized in that, The material of the first electrode layer is molybdenum.

3. The bulk acoustic resonator as described in claim 1, characterized in that, The thickness of the first electrode layer ranges from 200 nanometers to 350 nanometers.

4. The bulk acoustic resonator as described in claim 1, characterized in that, The material of the second electrode layer is molybdenum.

5. The bulk acoustic resonator as described in claim 1, characterized in that, The thickness of the second electrode layer ranges from 200 nanometers to 350 nanometers.

6. The bulk acoustic resonator as described in claim 1, characterized in that, The material of the piezoelectric layer includes aluminum nitride or scandium-doped aluminum nitride.

7. The bulk acoustic resonator as described in claim 1, characterized in that, The thickness of the piezoelectric layer ranges from 900 nanometers to 1100 nanometers.

8. The bulk acoustic resonator as described in claim 1, characterized in that, The first load layer is made of metal, and the material density of the first load layer is greater than that of the first electrode layer and the second electrode layer.

9. The bulk acoustic resonator as described in claim 8, characterized in that, The material of the first load layer is platinum.

10. The bulk acoustic resonator as described in claim 8, characterized in that, The thickness of the first load layer ranges from 80 nanometers to 120 nanometers.

11. The bulk acoustic resonator as described in claim 1, characterized in that, The material of the first dielectric layer is silicon dioxide.

12. The bulk acoustic resonator as described in claim 1, characterized in that, The thickness of the first dielectric layer ranges from 80 nanometers to 120 nanometers.

13. The bulk acoustic resonator as described in claim 1, characterized in that, The first load layer is located between the second medium portion and the first limiting portion.

14. The bulk acoustic resonator as described in claim 1, characterized in that, The first limiting portion is located between the second medium portion and the first load layer.

15. The bulk acoustic resonator as described in claim 1, characterized in that, The first electrode layer further includes a second attenuation portion located outside the first limiting portion, the second attenuation portion surrounding the first limiting portion; the first dielectric layer further includes a third dielectric portion located between the piezoelectric layer and the second attenuation portion.

16. The bulk acoustic resonator as described in claim 15, characterized in that, The first load layer has a second spacing dimension between its edge away from the resonant region and the edge of the second attenuation portion away from the resonant region, the second spacing dimension ranging from 0.5 micrometers to 3 micrometers.

17. The bulk acoustic resonator as described in claim 15, characterized in that, Also includes: A second attenuation region located outside the first restriction region is used to attenuate sound waves. The second attenuation region surrounds the first restriction region and includes a second attenuation part and the third dielectric part.

18. The bulk acoustic resonator as described in claim 1, characterized in that, The acoustic reflection layer includes: a cavity or a Bragg reflection layer.

19. The bulk acoustic resonator as described in claim 1, characterized in that, The operating frequency range of the bulk acoustic resonator is 2300MHz~2500MHz.

Images