Thin Film Bulk Acoustic Resonator and Method for Manufacturing the Same

Abstract

The present invention relates to a thin film bulk acoustic wave resonator and a manufacturing method thereof. The thin film bulk acoustic wave resonator includes: stacked lead electrodes, a piezoelectric layer, and an external electrode. The effective resonance region includes the region where the lead electrodes, the piezoelectric layer, and the external electrode overlap with each other in the direction perpendicular to the surface of the piezoelectric layer. The outside of the effective resonance region is an ineffective region; a first dielectric layer, with a first gap provided between the surface of the first dielectric layer and the surface of the lead electrode; the part of the lead electrode extending out of the first gap from the effective resonance region is a first lead portion; a second dielectric layer, with a second gap provided between the surface of the second dielectric layer and the surface of the external electrode; the external electrode is located within the region surrounded by the second gap or their boundaries coincide; a conductive column, one end of which is connected to the external electrode, and the other end is connected with a second lead portion, and the second lead portion extends out of the second gap from the effective resonance region; one of the lead electrode and the external electrode is located above the other.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor device manufacturing, and particularly to a thin film bulk acoustic resonator and a manufacturing method thereof. Background Art

[0002] Since the analog radio frequency communication technology was developed in the early 1990s, the radio frequency front-end module has gradually become the core component of communication devices. Among all radio frequency front-end modules, the filter has become the component with the strongest growth momentum and the greatest development prospect. With the rapid development of wireless communication technology and the increasing maturity of the 5G communication protocol, the market has put forward more stringent standards for all aspects of the performance of radio frequency filters. The performance of the filter is determined by the resonator units that make up the filter. In existing filters, the thin film bulk acoustic resonator (FBAR) has become one of the most suitable filters for 5G applications due to its small size, low insertion loss, large out-of-band rejection, high quality factor, high operating frequency, large power capacity, and good anti-electrostatic shock ability.

[0003] Generally, the thin film bulk acoustic resonator includes two thin film electrodes, and a piezoelectric thin film layer is provided between the two thin film electrodes. Its working principle is to utilize the piezoelectric thin film layer to generate vibrations under an alternating electric field, and the vibrations excite body acoustic waves propagating along the thickness direction of the piezoelectric thin film layer. These acoustic waves are reflected back at the air interfaces of the upper and lower electrodes and then reflect back and forth inside the thin film to form oscillations. When the propagation of the acoustic waves in the piezoelectric thin film layer is exactly an odd multiple of half a wavelength, a standing wave oscillation is formed.

[0004] However, for the cavity-type thin film bulk acoustic resonators currently fabricated, their quality factor (Q) cannot be further improved, so they cannot meet the requirements of high-performance radio frequency systems. Summary of the Invention

[0005] The purpose of the present invention is to provide a thin film bulk acoustic resonator and a manufacturing method thereof, which can improve the quality factor of the thin film bulk acoustic resonator and thus improve the device performance.

[0006] To achieve the above purpose, the present invention provides a thin film bulk acoustic resonator, comprising:

[0007] Stacked lead-out electrodes, a piezoelectric layer, and an external electrode. The effective resonance region includes the region where the lead-out electrodes, the piezoelectric layer, and the external electrode overlap with each other in the direction perpendicular to the surface of the piezoelectric layer, and the outside of the effective resonance region is the ineffective region;

[0008] A first dielectric layer, and a first gap is provided between the surface of the first dielectric layer and the surface of the lead-out electrode;

[0009] The part of the lead-out electrode extending out of the first gap from the effective resonance region is the first lead-out part;

[0010] A second dielectric layer, with a second gap provided between the surface of the second dielectric layer and the surface of the external electrode;

[0011] The external electrode is located within the region surrounded by the second gap or their boundaries coincide;

[0012] A conductive post, with one end connected to the external electrode and the other end connected to a second lead-out portion, and the second lead-out portion extends out of the second gap from the effective resonance region;

[0013] One of the lead-out electrode and the external electrode is located above the other.

[0014] The present invention also provides a manufacturing method of a thin-film bulk acoustic wave resonator, including:

[0015] Forming a first structure, the first structure includes: a lead-out electrode, a first sacrificial layer that at least covers the lead-out electrode and avoids the region where the first lead-out portion is located, and a first dielectric layer that at least surrounds the first sacrificial layer on the side of the first sacrificial layer;

[0016] Forming a piezoelectric layer;

[0017] Forming a second structure, the second structure includes: an external electrode, a second sacrificial layer that at least covers the external electrode, and a second dielectric layer that at least surrounds the second sacrificial layer on the side of the second sacrificial layer;

[0018] Forming a conductive post, penetrating through the second sacrificial layer and connecting the external electrode;

[0019] Forming a second lead-out portion, with one end connected to the conductive post and the other end extending out of the effective resonance region; removing the first sacrificial layer and the second sacrificial layer to form the first gap and the second gap.

[0020] The beneficial effects of the present invention are as follows:

[0021] By connecting the external electrode to an external signal through the conductive post and the second lead-out portion, the export area and impedance of the external electrode can be increased, while the coupling effect between electrodes is suppressed and heat conduction is enhanced; the first gap and the second gap serve as acoustic wave reflection structures to improve the quality factor of the resonator; the region where the conductive post is located forms an acoustic impedance mismatch region, which can cause the acoustic impedance at the boundary of the effective resonance region to mismatch with the acoustic impedance inside the effective resonance region, facilitating the improvement of the quality factor of the resonator.

[0022] Furthermore, the projection of the conductive post on the surface of the carrier substrate is a closed or gapped ring, which can further suppress the loss of transverse acoustic wave energy and improve the quality factor of the resonator.

[0023] Furthermore, all side edges of the external electrode and partial side edges of the lead-out electrode are exposed in the cavity, which can suppress the transverse wave loss at the side edges of the electrode.

[0024] Furthermore, the edge of the piezoelectric layer is exposed in the cavity, which can further suppress the transverse wave loss.

[0025] Furthermore, the piezoelectric layer is a complete film layer, which can ensure the piezoelectric properties of the piezoelectric layer.

[0026] Furthermore, the piezoelectric layer is formed on a flat electrode layer, which can enable the piezoelectric layer to have a good lattice orientation, improve the piezoelectric properties of the piezoelectric layer, and thus improve the overall performance of the resonator. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0028] Figure 1 The structural schematic diagram of a thin film bulk acoustic wave resonator according to Embodiment 1 of the present invention is shown.

[0029] Figure 2 The structural schematic diagram of a thin film bulk acoustic wave resonator according to Embodiment 2 of the present invention is shown.

[0030] Figure 3 The structural schematic diagram of a thin film bulk acoustic wave resonator according to Embodiment 3 of the present invention is shown.

[0031] Figures 4 to 13 The corresponding structural schematic diagrams in different steps of the manufacturing method of a thin film bulk acoustic wave resonator according to Embodiment 4 of the present invention are shown.

[0032] Figures 14 to 19 The corresponding structural schematic diagrams in different steps of the manufacturing method of a thin film bulk acoustic wave resonator according to Embodiment 5 of the present invention are shown.

[0033] Figures 20 to 27 The corresponding structural schematic diagrams in different steps of the manufacturing method of a thin film bulk acoustic wave resonator according to Embodiment 6 of the present invention are shown.

[0034] Figures 28 to 33 The corresponding structural schematic diagrams in different steps of the manufacturing method of a thin film bulk acoustic wave resonator according to Embodiment 7 of the present invention are shown.

[0035] Description of the Reference Numerals:

[0036] 100 - Carrier substrate; 101A - Dielectric layer surrounding the first sacrificial layer at least on the side of the first sacrificial layer; 101B - First passivation layer; 101 - First dielectric layer; 102A - Dielectric layer surrounding the second sacrificial layer at least on the side of the second sacrificial layer; 102B - Second passivation layer; 102 - Second dielectric layer; 200 - Temporary substrate; 201’ - Lead-out electrode layer; 201 - Lead-out electrode; 202 - Piezoelectric layer; 203’ - External electrode layer; 203 - External electrode; 210 - First sacrificial layer; 220 - Second sacrificial layer; 211 - First gap; 221 - Second gap; 401 - Conductive pillar; 402 - Second lead-out portion; 403 - First lead-out portion; 10 - First cavity; 2021 - Resonating portion; 2022 - Overlapping portion. Detailed implementation manners

[0037] For the cavity-type thin film bulk acoustic wave resonator fabricated currently, there is a problem of transverse wave loss, which makes it impossible to further improve the quality factor (Q), so it cannot meet the requirements of high-performance radio frequency systems.

[0038] The thin film bulk acoustic wave resonator and its manufacturing method of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. According to the following description and drawings, the advantages and features of the present invention will be clearer. However, it should be noted that the concept of the technical solution of the present invention can be implemented in various different forms and is not limited to the specific embodiments described herein. The accompanying drawings are all in very simplified forms and use non-precise scales, only for facilitating and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0039] The terms "first", "second", etc. in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a specific order or time sequence. It should be understood that, under appropriate circumstances, these terms can be replaced, for example, so that the embodiments of the present invention described herein can be operated in an order different from that described or shown herein. Similarly, if the method described herein includes a series of steps, and the order of these steps presented herein is not necessarily the only order in which these steps can be executed, and some of the described steps can be omitted and / or some other steps not described herein can be added to the method. If the components in a certain drawing are the same as those in other drawings, although these components can be easily recognized in all drawings, for the sake of clearer description of the drawings, this specification will not label the reference numerals of all the same components in each drawing.

[0040] Example 1

[0041] Embodiment 1 of the present invention provides a thin film bulk acoustic wave resonator. Figure 1 For the structural schematic diagram of the thin film bulk acoustic wave resonator of Embodiment 1 of the present invention, please refer to Figure 1, the thin film bulk acoustic resonator includes:

[0042] Stacked lead-out electrodes 201, a piezoelectric layer 202, and an external electrode 203. The effective resonance region includes the region where the lead-out electrodes 201, the piezoelectric layer 202, and the external electrode 203 overlap with each other in the direction perpendicular to the surface of the piezoelectric layer 202. The outside of the effective resonance region is the invalid region;

[0043] A first dielectric layer 101, with a first gap 211 provided between the surface of the first dielectric layer 101 and the surface of the lead-out electrode 201;

[0044] A second dielectric layer 102, with a second gap 221 provided between the surface of the second dielectric layer 102 and the surface of the external electrode 203;

[0045] The external electrode 203 is located within the region surrounded by the second gap 221 or their boundaries coincide;

[0046] A conductive column 401, with one end connected to the external electrode 203 and the other end connected to a second lead-out portion 402. The second lead-out portion 402 extends out of the second gap 221 from the effective resonance region;

[0047] One of the lead-out electrode 201 and the external electrode 203 is located above the other.

[0048] Reference Figure 1 , in this embodiment, it further includes a carrier substrate 100. The first dielectric layer 101 and the carrier substrate 100 can be bonded or deposited. The material of the bonding layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, or ethyl silicate. In this embodiment, the first dielectric layer 101 is formed on the carrier substrate 100 by deposition. The first dielectric layer can be a single-layer structure or a laminated structure. The material of the first dielectric layer can include, but is not limited to, one of materials such as silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, etc., but the technology of the present invention is not limited thereto.

[0049] The material of the carrier substrate 100 can be any suitable substrate well-known to those skilled in the art. For example, it can be at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon germanium carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III / V compound semiconductors.

[0050] Above the first dielectric layer 101, there are sequentially arranged, from bottom to top, a lead-out electrode 201, a piezoelectric layer 202, and an external connection electrode 203 which are stacked. The external connection electrode 203 and the lead-out electrode 201 can use any suitable conductive material or semiconductor material well-known to those skilled in the art. Among them, the conductive material can be a metal material with conductive properties. For example, it can be made of one of metals such as molybdenum (Mo), aluminum (Al), copper (Cu), tungsten (W), tantalum (Ta), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), chromium (Cr), titanium (Ti), gold (Au), osmium (Os), rhenium (Re), palladium (Pd), etc., or a stack formed by the above metals. The semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, etc. The material of the piezoelectric layer 202 can use piezoelectric materials with a wurtzite crystal structure such as aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), quartz, potassium niobate (KNbO3), or lithium tantalate (LiTaO3), and their combinations. When the piezoelectric layer 202 includes aluminum nitride (AlN), the piezoelectric layer 202 may further include rare earth metals, such as at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, when the piezoelectric layer 202 includes aluminum nitride (AlN), the piezoelectric layer 202 may further include transition metals, such as at least one of zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). Any suitable method well-known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition, can be used to deposit and form the piezoelectric layer 202.

[0051] In this embodiment, the middle of the upper surface of the first dielectric layer 101 is sunken, and the outer periphery is convex. There is a first gap 211 between the lower surface of the lead-out electrode 201 and the upper surface of the sunken area of the first dielectric layer 101. In this embodiment, the lead-out electrode 201 includes two parts. One part is located within the first gap 211, and the other part is located outside the first gap 211. The two parts are an integral structure. The part located outside the first gap 211 is the first lead-out part 403 for connecting an external signal. The edge of the part located within the first gap 211 is exposed in the first gap 211. The bottom surface of the piezoelectric layer 202 at the outer periphery of the edge of the lead-out electrode 201 is also exposed in the first gap 211. The piezoelectric layer 202 is a horizontally complete film layer, and extends around to above the surface of the convex area of the first dielectric layer 101. The partial edge of the lead-out electrode 201 being exposed in the first gap 211 can make the edge of the lead-out electrode 201 form a reflection interface with the air, cause acoustic impedance mismatch, suppress the leakage of transverse waves, and thus improve the quality factor (Q value) of the resonator.

[0052] The second dielectric layer 102 is located above the first dielectric layer 101. The material of the second dielectric layer 102 may include, but is not limited to, one of materials such as silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, etc. The second dielectric layer may be a single-layer structure or a stacked structure. In this embodiment, the lower surface of the second dielectric layer 102 is recessed in the middle and protrudes on the outer periphery. A second gap 221 is provided between the upper surface of the external connection electrode 203 and the lower surface of the recessed area of the second dielectric layer 102. In this embodiment, the boundary of the second gap 221 is larger than the boundary of the external connection electrode 203, so that the outer periphery of the edge of the external connection electrode 203 is exposed in the second gap 221. The edge of the external connection electrode 203 is completely exposed in the second gap 221, which can form a reflection interface between the edge of the external connection electrode 203 and the air, cause acoustic impedance mismatch, suppress the leakage of transverse waves, and thus improve the quality factor (Q value) of the resonator.

[0053] In this embodiment, the recessed area of the second dielectric layer 102 and the second gap 221 are disposed opposite to the recessed area of the first dielectric layer 101 and the first gap 211, and the protruding area of the second dielectric layer 102 is disposed opposite to the protruding area of the first dielectric layer 101. The area between the two recessed areas is the area where the effective resonance area of the resonator is located. The effective resonance area includes the area where the lead-out electrode 201, the piezoelectric layer 202, and the external connection electrode 203 overlap with each other in the direction perpendicular to the surface of the piezoelectric layer 202. In this embodiment, the boundaries of the projections of the first gap 211 and the second gap 221 in the direction of the piezoelectric layer 202 surround the boundary of the projection of the effective resonance area in the direction of the piezoelectric layer 202. The meaning of "surround" here is that the boundary of the effective resonance area is within the first gap 211 and the second gap 221, or the boundary of the effective resonance area coincides with the boundary of the first gap 211 and / or the second gap 221. Figure 1 The situation shown is that the boundary of the effective resonance area is within the first gap 211 and the second gap 221. In this embodiment, the boundaries of the projections of the first gap 211 and the second gap 221 in the direction of the piezoelectric layer 202 surround the boundaries of the projections of the lead-out electrode 201 and the external connection electrode 203 in the direction of the piezoelectric layer 202. The meaning of "surround" is the same as that described above.

[0054] In this embodiment, the piezoelectric layer 202 includes a resonant portion 2021 and a lapping portion 2022 located on the outer periphery of the resonant portion. The resonant portion 2021 is located in the effective resonance region, and the lapping portion 2022 is located outside the effective resonance region. Specifically, in this embodiment, the piezoelectric layer 202 is a complete film layer, and the resonant portion 2021 and the lapping portion 2022 are of an integral structure. The first gap 305 and the second gap 306 are isolated from each other by the piezoelectric layer 202. In another embodiment, the first gap and the second gap can be connected through a plurality of through holes distributed in the invalid region. For example, the through holes penetrate the piezoelectric layer in the invalid region (or penetrate the piezoelectric layer and the lead-out electrode simultaneously). Or the first gap and the second gap are connected through a non-closed annular through hole surrounding the effective region. At this time, the inner wall of the non-closed annular through hole can form the boundary of the effective resonance region, and its inner wall can also be located outside the boundary of the effective resonance region.

[0055] In this embodiment, a conductive column 401 is provided on the upper surface of the external electrode 203. The conductive column 401 can be a single or multiple discontinuous columnar shapes. In this embodiment, the conductive column 401 is arranged at the edge of the effective resonance region, and its projection in the surface direction of the piezoelectric layer 202 is annular, where the annular shape includes a discontinuous or closed ring. The shape of the ring can be circular, elliptical, polygonal, or an irregular shape composed of arcs and straight edges. A closed ring means that the conductive column 401 is continuous, and an unclosed ring means that the conductive column 401 is discontinuous. The region where the conductive column 401 is located forms an acoustic impedance mismatch with the effective resonance region, so as to be able to reflect the outward-propagating transverse acoustic wave back into the effective resonance region, suppress the leakage of transverse clutter, reduce energy loss, and improve the quality factor (Q value) of the resonator. When the projection of the conductive column 401 on the surface of the piezoelectric layer 302 is a closed ring, it is more beneficial to prevent the transverse leakage of acoustic waves.

[0056] The other end of the conductive column 401 is connected with a second lead-out portion 402. In this embodiment, the second lead-out portion 402 is buried in the second dielectric layer 102. In other embodiments, the second lead-out portion 402 can also be located on the lower surface of the recessed region of the second dielectric layer 102. Figure 1 As can be seen, the second lead-out portion 402 is led out from the side where the effective resonance region is located to the outside. The second lead-out portion 402 can be used as a signal input end to introduce an electrical signal into the external electrode 203 in the effective resonance region, or as a signal output end to output the electrical signal on the external electrode 203. When the first lead-out portion 403 is used as a signal input end, the second lead-out portion 402 is used as a signal output end, and vice versa.

[0057] In this embodiment, the projections of the first lead-out portion 403 and the second lead-out portion 402 in the direction of the piezoelectric layer are staggered from each other. This can avoid high-frequency coupling caused by potential floating and prevent the parasitic capacitance effect.

[0058] The material of the conductive pillar 401 is a conductive material, such as materials with low resistivity like gold, silver, tungsten, platinum, aluminum, copper, etc. The material of the second lead-out part 402 can refer to the material of the conductive pillar, and the material of the conductive pillar can be the same as or different from the material of the second lead-out part.

[0059] Example 2

[0060] Embodiment 2 of the present invention provides a thin film bulk acoustic wave resonator. Figure 2 It is a schematic structural diagram of the thin film bulk acoustic wave resonator of Embodiment 2 of the present invention. The difference between this embodiment and Embodiment 1 is that in this embodiment, the resonant part 2021 of the piezoelectric layer 202 is located in the effective resonance region, and the overlapping part 2022 is located outside the effective resonance region, and the resonant part 2021 and the overlapping part 2022 are separated from each other. Please refer to Figure 2 , and the specific structure is as follows:

[0061] The first gap 211 and the second gap 221 communicate with each other to form a cavity. The resonant part 2021 is completely located inside the cavity, and the overlapping part 2022 is located outside the cavity. The overlapping part 2022 and the resonant part 2021 are completely separated, so that the outer periphery of the resonant part 2021 is exposed in the cavity. Figure 2 As shown in , the edge of the resonant part 2021 of the piezoelectric layer coincides with the edge of the lead-out electrode 201 and part of the edge of the external connection electrode 203, constituting the edge of the effective resonance region. At this time, the resonant part 2021 is entirely located in the effective resonance region. In another embodiment, there are both connected parts and separated parts between the resonant part 2021 and the overlapping part 2022. The edge of the resonant part 2021 exposed in the cavity forms a reflection interface with the air, causing acoustic impedance mismatch and suppressing the leakage of transverse waves, thereby improving the quality factor (Q value) of the resonator. When the resonant part 2021 and the overlapping part are completely separated, so that the edge of the resonant part 2021 is completely exposed in the cavity, the effect of preventing the leakage of transverse waves is the best. When there are both connected parts and separated parts between the resonant part 2021 and the overlapping part 2022, the structural strength of the resonator can be improved. Other structural parts of this embodiment refer to Embodiment 1 and will not be elaborated here.

[0062] Example 3

[0063] Embodiment 3 of the present invention provides a thin film bulk acoustic wave resonator. Figure 3Schematic diagram of the structure of the thin film bulk acoustic resonator according to Embodiment 3 of the present invention. The difference between this embodiment and Embodiment 1 is that: the piezoelectric layer 202 is a complete film layer, the overlapping portion 2022 and the resonant portion 2021 are connected together and are an integral structure. A part of the conductive column 401 is in contact with the second dielectric layer 102 at the edge of the second gap 221, and a part is located in the second gap 221, and there is a distance from the boundary of the second gap 221. The conductive column 401 can also be entirely located at the edge of the second gap 221, or the conductive column 401 is not in contact with the edge of the second gap 221.

[0064] In the above Embodiments 1 to 3, the external electrode is located above the lead-out electrode. However, in these embodiments, it is also possible that the external electrodes are all located below the lead-out electrode.

[0065] The manufacturing method for forming a thin film bulk acoustic resonator in the present invention includes:

[0066] Step S1, forming a first structure, the first structure includes: a lead-out electrode, a first sacrificial layer that at least covers the lead-out electrode and avoids the region where the first lead-out portion is located, and a dielectric layer that at least surrounds the first sacrificial layer on the side of the first sacrificial layer;

[0067] Step S2, forming a piezoelectric layer;

[0068] Step S3, forming a second structure, the second structure includes: an external electrode, a second sacrificial layer that at least covers the external electrode, and a dielectric layer that at least surrounds the second sacrificial layer on the side of the second sacrificial layer;

[0069] Step S4, forming a conductive column that penetrates the second sacrificial layer and connects the external electrode;

[0070] Step S5, forming a second lead-out portion, one end of which is connected to the conductive column and the other end extends out of the effective resonance region;

[0071] Step S6, removing the first sacrificial layer and the second sacrificial layer to form the first gap and the second gap.

[0072] The order between the above steps can be carried out sequentially, or may not be carried out sequentially.

[0073] In one solution (corresponding to Embodiment 4, refer to Figures 4 to 13 ): providing a temporary substrate; performing Step S1 on the temporary substrate to form a first structure. Bonding a carrier substrate on the first structure and removing the temporary substrate; then sequentially performing Steps S3 - S5 on the carrier substrate to sequentially form a second structure, a conductive column, and a second lead-out portion.

[0074] In another solution (which can correspond to Embodiment 5, refer to Figures 14 to 19: Provide a temporary substrate; perform step S3 on the temporary substrate to form a second structure, then perform step S2 to form a piezoelectric layer, and then perform step S1 to form a first structure. Bond a carrier substrate to the first structure. After removing the temporary substrate, sequentially perform step S4 and step S5 to form a conductive pillar and a second lead-out portion.

[0075] In another solution (which can correspond to Embodiment 6, refer to Figures 20 - 27 ): Provide a carrier; perform step S5 on the carrier substrate to form a second lead-out portion, then perform step S4 to form a conductive pillar, then perform step S3 to form a second structure, then perform step S2 to form a piezoelectric layer to cover the second structure, and finally perform step S1 to form a first structure on the second structure.

[0076] In yet another solution (which can correspond to Embodiment 7, refer to Figures 28 - 33 ): Provide a temporary substrate; sequentially perform step S3, step S4, and step S5 on the temporary substrate to sequentially form a second structure, a conductive pillar, and a second lead-out portion. Bond a carrier substrate to the side where the second lead-out portion is located. Remove the temporary substrate and perform step S1 on the carrier substrate to form a first structure.

[0077] In the above several solutions, for step S2 of forming the piezoelectric layer: it can be formed 1) before performing step S1. For example, first form an external electrode layer and a piezoelectric layer on the temporary substrate, and then perform step S1 to form a first structure. It can also be formed 2) after performing step S1 and before performing step S3. For example, perform step S1 on the temporary substrate to form a first structure, perform step S2 on the first structure to form a piezoelectric layer, and then perform step S3 on the piezoelectric layer to form a second structure. The piezoelectric layer is a film layer with both an effective resonance region and an ineffective region distributed, or it can also be a film layer that is only located in the effective resonance region after being patterned.

[0078] The following is a detailed description of each embodiment with reference to the accompanying drawings:

[0079] Example 4

[0080] Figures 4 to 13 It is a schematic diagram of the structures corresponding to different steps in the manufacturing method of a thin film bulk acoustic resonator according to Embodiment 4 of the present invention. Hereinafter, reference will be made to Figures 4 to 13 to describe this embodiment in detail.

[0081] Refer to Figures 4 - 7 , provide a temporary substrate 200, and form a first structure on the temporary substrate. The first structure includes: a lead-out electrode 201, a first sacrificial layer 210 that at least covers the lead-out electrode 201 and avoids the region where the first lead-out portion 403 is located, and a dielectric layer 101A that at least surrounds the first sacrificial layer 210 on the side of the first sacrificial layer 210.

[0082] Specifically, referring to Figure 4 , a temporary substrate 200 is provided, and an external electrode layer 203', a piezoelectric layer 202, and a lead-out electrode layer 201' are formed on the temporary substrate 200.

[0083] The material of the temporary substrate 200 can be at least one of the materials mentioned below: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon germanium carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III / V compound semiconductors.

[0084] In addition, for facilitating the subsequent peeling of the temporary substrate 200, an isolation layer can also be formed on the temporary substrate 200. The isolation layer is located between the temporary substrate 200 and the external electrode layer 203'. In the subsequent peeling process, the temporary substrate 200 can be separated from the subsequently formed external electrode layer 203' by etching the isolation layer, which helps to quickly peel the temporary substrate and improve the process manufacturing efficiency. If no isolation layer is formed between the temporary substrate 200 and the external electrode layer 203', the temporary substrate can be removed by mechanical grinding or other means subsequently. The materials of the isolation layer include but are not limited to at least one of silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3), and aluminum nitride (AlN). The isolation layer can be formed by chemical vapor deposition, magnetron sputtering, evaporation, or other methods.

[0085] First, the external electrode layer 203' is deposited on the temporary substrate 200, then the piezoelectric layer 202 is deposited on the external electrode layer 203', and finally the lead-out electrode layer 201' is deposited on the piezoelectric layer 202. Forming the piezoelectric layer 202 on a flat external electrode layer 203' can enable the piezoelectric layer 202 to have a better lattice orientation, improve the piezoelectric properties of the piezoelectric layer 202, and further improve the overall performance of the resonator.

[0086] The material of the piezoelectric layer 202 refers to the description of the previous structural embodiment. Any suitable method well-known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition, can be used to deposit and form the piezoelectric layer 202. The materials of the lead-out electrode layer 201' and the external electrode layer 203' refer to the introduction of the materials of the lead-out electrode and the external electrode in the previous structural embodiment. The lead-out electrode layer 201' or the external electrode layer 203' can be formed by physical vapor deposition methods such as magnetron sputtering and evaporation, or chemical vapor deposition methods.

[0087] Referring to Figure 5, after forming the lead-out electrode layer 201', the lead-out electrode layer 201' is patterned to form the lead-out electrode 201. The method of patterning the lead-out electrode layer 201' can etch the lead-out electrode layer 201' using an etching process, which can be a wet etching process or a dry etching process. Preferably, a dry etching process is used. Dry etching includes, but is not limited to, reactive ion etching (RIE), ion beam etching, plasma etching, or laser cutting. In this embodiment, the lead-out electrode 201 includes two parts, one part is located in the first gap formed subsequently, and the other part is located outside the first gap. The part extending outside the first gap is the first lead-out part, and the two parts are an integral structure.

[0088] Reference Figure 6 , a first sacrificial layer material is formed to cover the lead-out electrode 201 and the piezoelectric layer 202. The first sacrificial material is patterned to form the first sacrificial layer 210. In this embodiment, the first sacrificial layer 210 covers a part of the lead-out electrode 201 and the piezoelectric layer outside the lead-out electrode 210, covering the edges of a part of the lead-out electrode. The part of the lead-out electrode not covered by the first sacrificial layer constitutes the first lead-out part for connecting to an external electrical signal. The first sacrificial layer 210 forms the first gap after being released in a subsequent process. The position of the first sacrificial layer 210 determines the position of the first gap, and the height of the first sacrificial layer 210 determines the height of the first gap. The first sacrificial layer material includes phosphosilicate glass, low-temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide, or photoresist, and can be formed by chemical vapor deposition.

[0089] Reference Figure 7 , a dielectric layer 101A is formed to surround the first sacrificial layer at least on the side of the first sacrificial layer, covering the first sacrificial layer 210 and the lead-out electrode 201 and the piezoelectric layer outside the first sacrificial layer 210. The material of the dielectric layer 101A that surrounds the first sacrificial layer at least on the side of the first sacrificial layer can be one or a combination of silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3), and aluminum nitride. It can be formed by physical vapor deposition or chemical vapor deposition.

[0090] Reference Figure 8, a release hole 212 is formed in the dielectric layer 101A that is at least on the side of the first sacrificial layer and surrounds the first sacrificial layer above the first sacrificial layer, and the first sacrificial layer is removed through the release hole 212. To completely release the first sacrificial layer, the number of release holes can be multiple, and they are distributed in different regions above the first sacrificial layer. According to the selected material of the first sacrificial layer, a corresponding removal method is adopted. For example, when the material of the first sacrificial layer is polyimide or photoresist, an ashing method is used for removal. The specific ashing method is that at a temperature of 250 degrees Celsius, oxygen passes through the release hole 212 to chemically react with the material of the first sacrificial layer, generating gaseous substances that volatilize. When the material of the first sacrificial layer is low-temperature silicon dioxide, it is removed by reacting with a hydrofluoric acid solvent. After removing the first sacrificial layer, a first gap 211 is formed between the surface of the lead electrode 201 and the first dielectric layer 101A of the first layer.

[0091] Reference Figure 9 , in this embodiment, it further includes forming a carrier substrate 100 on the upper surface of the dielectric layer 101A that is at least on the side of the first sacrificial layer and surrounds the first sacrificial layer. The carrier substrate 100 can be bonded to the dielectric layer 101A that is at least on the side of the first sacrificial layer and surrounds the first sacrificial layer by a bonding method. The material of the bonding layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, or ethyl silicate. The purpose of forming the carrier substrate 100 is to provide support strength, so that the thickness of the dielectric layer 101A that is at least on the side of the first sacrificial layer and surrounds the first sacrificial layer can be made thinner, saving process time.

[0092] Reference Figure 10 , the temporary substrate 200 is removed. When an isolation layer is formed on the temporary substrate 200, the temporary substrate 200 can be removed by etching the isolation layer. If no isolation layer is formed between the temporary substrate 200 and the external electrode layer 203', the temporary substrate 200 can be removed by mechanical grinding or other means.

[0093] Reference Figure 11 , the external electrode layer is patterned to form the external electrode 203. In this embodiment, the edge of the external electrode 203 is located above the region surrounded by the first gap 211. In this embodiment, the edge of the external electrode 203 is also located within the region surrounded by the second gap formed in the subsequent process. Reference Figure 2, in another embodiment, after forming the external electrode 203, the piezoelectric layer 202 above the first gap 211 and on the outer periphery of the external electrode may also be etched, so that the piezoelectric layer 202 is divided into a resonant portion 2021 and an overlapping portion 2022 located on the outer periphery of the resonant portion 2021. All or part of the edge of the resonant portion 2021 is exposed in the cavity. When all the edges of the resonant portion 2021 are exposed in the cavity, the first gap and the second gap formed in the subsequent process are interconnected. The function of the edge of the resonant portion 2021 exposed in the cavity refers to the relevant description of the previous structural embodiment.

[0094] Reference Figure 12 , a second sacrificial layer material is formed to cover the external electrode 203 and the piezoelectric layer 202. The second sacrificial material is patterned to form a second sacrificial layer 220, and the second sacrificial layer 220 at least covers the external electrode 203. In this embodiment, the second sacrificial layer 220 also covers the piezoelectric layer 202 on the outer periphery of the external electrode 201. The second sacrificial layer 220 forms a second gap after being released in the subsequent process. The second sacrificial layer material and the forming method refer to the first sacrificial layer material and the forming method. After forming the second sacrificial layer 220, a dielectric layer 102A is formed that at least surrounds the second sacrificial layer on the side of the second sacrificial layer, covering the second sacrificial layer 220 and the piezoelectric layer 202 on the outer periphery of the second sacrificial layer. The material and the forming method of the dielectric layer 102A that at least surrounds the second sacrificial layer on the side of the second sacrificial layer refer to the material and the forming method of the first dielectric layer. After forming the dielectric layer 102A that at least surrounds the second sacrificial layer on the side of the second sacrificial layer, a conductive column 401 is formed on the surface of the external electrode 203.

[0095] Continue to refer to Figure 12 , a conductive column 401 is formed on the surface of the external electrode. Specifically, a first through hole is formed, penetrating the second sacrificial layer 220 and the dielectric layer 102A that at least surrounds the second sacrificial layer above the second sacrificial layer, and a conductive material is formed in the first through hole to form the conductive column 401. The first through hole can be formed by an etching process or a drilling process. The conductive material can be formed in the first through hole by a deposition or electroplating method, and the conductive material includes materials with low resistivity such as gold, silver, tungsten, platinum, aluminum, and copper. In this embodiment, the conductive column 401 is formed at the edge of the effective resonance region, and its position, structure, and function refer to the relevant description of the previous structural embodiment.

[0096] Reference Figure 13, a release hole is formed in the dielectric layer 102A that is above the second sacrificial layer and surrounds the second sacrificial layer at least on the side of the second sacrificial layer, and the second sacrificial layer is removed through the release hole. A second gap 221 is formed between the surface of the external electrode 203 and the dielectric layer 102A that surrounds the second sacrificial layer at least on the side of the second sacrificial layer. After removing the second sacrificial layer, a second lead-out portion 402 is formed, including: forming a second passivation layer 102B; etching the second passivation layer 102B to form a groove; forming a conductive material layer in the groove as the second lead-out portion 402; or, forming a conductive material layer and patterning the conductive material layer to form the second lead-out portion 402; forming a second passivation layer 102B to cover the second lead-out portion 402; the dielectric layer that surrounds the second sacrificial layer at least on the side of the second sacrificial layer includes the second passivation layer 102B. When the second passivation layer 102B is formed first and then the second lead-out portion 402 is formed, the surfaces of the second passivation layer 102B and the second lead-out portion 402 are flush, and then a dielectric layer can be formed on this flush surface, which is convenient for subsequent bonding of the carrier substrate; when the second lead-out portion 402 is formed first and then the second passivation layer 102B is formed, the surfaces of the second passivation layer 102B and the second lead-out portion 402 are flush or the second passivation layer 102B covers the second lead-out portion 402. If they are flush, a dielectric layer is formed on this flush surface, which is convenient for subsequent bonding of the carrier substrate.

[0097] The second lead-out portion 402 extends out of the region where the second gap 221 is located. In this embodiment, the second lead-out portion 402 is strip-shaped and extends outwards from the side where the second gap 221 is located. In another embodiment, the second lead-out portion 402 is planar. It should be understood that the function of the second lead-out portion 402 is to connect external signals and play an electrical connection role, and its shape and area can be flexibly selected according to the situation.

[0098] In this embodiment, outside the effective resonance region, the projections of the first lead-out portion 403 and the second lead-out portion 402 in the direction of the piezoelectric layer 202 are staggered from each other.

[0099] In the present invention, the release hole can also be formed to remove the second sacrificial layer after the second lead-out portion is formed.

[0100] Variant Example 1 of Embodiment 4:

[0101] In Embodiment 4, an external connection electrode layer, a piezoelectric layer, and a lead-out electrode layer are sequentially formed on a temporary substrate; then, the lead-out electrode layer is patterned to form the lead-out electrode; after forming the first structure, when the carrier substrate is bonded and the temporary substrate is removed, the external connection electrode layer is patterned to form the external connection electrode; then, the second structure, the conductive column, and the second lead-out portion are formed. When etching to form the lead-out electrode or the external connection electrode, the piezoelectric layer is never etched, the integrity of the piezoelectric layer is retained, and the piezoelectric layer is distributed in both the effective region and the ineffective region. The first gap and the second gap are separated from each other by the piezoelectric layer. Therefore, the first sacrificial layer and the second sacrificial layer are not connected to each other and need to be removed separately.

[0102] In Variant Example 1, after forming the lead-out electrode or after forming the external connection electrode, the piezoelectric layer can be patterned to remove the piezoelectric layer in the ineffective region or form an air gap around the piezoelectric layer in the effective resonance region. For the advantages of this case, please refer to the corresponding part in the structural embodiment.

[0103] Correspondingly, in this Variant Example 1, after forming the second sacrificial layer, the first sacrificial layer still exists, and the second sacrificial layer also fills the periphery of the patterned piezoelectric layer. At this time, the first sacrificial layer and the second sacrificial layer are connected to each other, and the first sacrificial layer and the second sacrificial layer can be removed simultaneously.

[0104] Variant Example 2 of Embodiment 4:

[0105] In this Variant Example 2, a piezoelectric layer and a lead-out electrode layer are sequentially formed on a temporary substrate; the lead-out electrode layer is patterned to form the lead-out electrode. Then, referring to the method of Embodiment 4, the first sacrificial layer and a dielectric layer surrounding at least the side surface of the first sacrificial layer are formed. The first sacrificial layer covers the top surface and the side surface of the lead-out electrode; after removing the temporary substrate, bonding the carrier substrate, and turning it over, an external connection electrode layer is formed, and the external connection electrode layer is patterned to form the external connection electrode. Then, continuing to refer to the method of Embodiment 4, a conductive column, a second lead-out portion, a second sacrificial layer, and a dielectric layer surrounding at least the side surface of the second sacrificial layer are formed.

[0106] In this Variant Example 2, the piezoelectric layer can be maintained to be distributed in both the ineffective region and the effective resonance region. At this time, since the first sacrificial layer and the second sacrificial layer are separated from each other, the first sacrificial layer and the second sacrificial layer need to be removed separately.

[0107] In the second modification example, it is also possible that after forming the lead-out electrode or after forming the external connection electrode, the piezoelectric layer is patterned to remove the piezoelectric layer in the inactive region or to form an air gap around the piezoelectric layer in the active resonance region. In this case, after forming the second sacrificial layer, the first sacrificial layer still exists, and the second sacrificial layer also fills the periphery of the patterned piezoelectric layer. At this time, the first sacrificial layer and the second sacrificial layer are interconnected, and the first sacrificial layer and the second sacrificial layer can be removed simultaneously.

[0108] Modification example three of Embodiment 4

[0109] In the third modification example, the external connection electrode layer, the piezoelectric layer, and the lead-out electrode layer are not sequentially formed on the temporary substrate. In this embodiment, a lead-out electrode and a planarization layer are formed on the temporary substrate, and the lead-out electrode and the planarization layer are flush with each other; then, referring to the method of Embodiment 4, a first sacrificial layer and a dielectric layer that surrounds the first sacrificial layer at least on the side thereof are formed.

[0110] Then, the carrier substrate is bonded, the temporary substrate is removed, and a piezoelectric layer is formed on the flush surface of the lead-out electrode and the planarization layer on the carrier substrate.

[0111] Next, referring to the method of Embodiment 4, an external connection electrode layer is formed on the piezoelectric layer; the external connection electrode layer is patterned to form an external connection electrode; and a dielectric layer, a second sacrificial layer, a conductive pillar, and a second lead-out portion that surround the second sacrificial layer at least on the side thereof are formed.

[0112] In the third modification example, the piezoelectric layer can be located in the active resonance region and the inactive region. At this time, the first sacrificial layer and the second sacrificial layer are separated from each other and need to be removed separately.

[0113] In the third modification example, it is also possible to pattern the piezoelectric layer before or after patterning the external connection electrode layer to remove the piezoelectric layer in the inactive region or to form an air gap around the piezoelectric layer in the active resonance region. In this case, after forming the second sacrificial layer, the first sacrificial layer still exists, and the second sacrificial layer also fills the periphery of the patterned piezoelectric layer. At this time, the first sacrificial layer and the second sacrificial layer are interconnected, and the first sacrificial layer and the second sacrificial layer can be removed simultaneously.

[0114] Example 5

[0115] Embodiment 5 of the present invention provides a method for manufacturing a thin film bulk acoustic resonator. Figures 14 to 19 is a schematic structural diagram corresponding to different steps in the method for manufacturing a thin film bulk acoustic resonator according to Embodiment 5 of the present invention. Hereinafter, reference will be made to Figures 14 to 19 This embodiment will be described in detail.

[0116] In Example 4, a first structure is formed on a temporary substrate. In this example, a second structure is formed on the temporary substrate first.

[0117] Reference Figure 14 and Figure 15 , a temporary substrate 200 is provided, and a second structure is formed on the temporary substrate 200. Specifically, a second sacrificial layer 220 and a dielectric layer 102A that surrounds the second sacrificial layer at least on the side thereof are formed first, and then an external electrode 203 is formed. The second sacrificial layer only covers the top surface (the surface close to the temporary substrate 200) of the external electrode 203 or covers the top surface and the side surface of the external electrode. Among them, the dielectric layer 102A that surrounds the second sacrificial layer at least on the side thereof covers the side surface of the second sacrificial layer and the side surface of the external electrode or covers the side surface, the top surface of the second sacrificial layer and the side surface of the external electrode.

[0118] Specific methods for forming the external electrode include: Reference Figure 15 , the second sacrificial layer 220 is etched to form a groove, and a conductive material is filled in the groove as the external electrode. If the conductive material is formed outside the groove, the conductive material outside the groove needs to be removed, which can be removed by chemical mechanical polishing or etching.

[0119] A modified method for forming the external electrode can also be: an external electrode layer is formed on the surface of the second sacrificial layer and the dielectric layer that surrounds the second sacrificial layer at least on the side thereof, and then the external electrode layer is patterned to form the external electrode. At this time, the external electrode is located on the second sacrificial layer rather than embedded in the second sacrificial layer.

[0120] Among them, the method for forming the second sacrificial layer 220 and the dielectric layer 102A that surrounds the second sacrificial layer at least on the side thereof can refer to Example 4.

[0121] Reference Figure 16 , after forming the first structure, a piezoelectric layer 202 is formed on the temporary substrate. The specific formation method can refer to the relevant content of forming the piezoelectric layer in Example 4.

[0122] Continue to refer to Figure 16 , after forming the piezoelectric layer 202, a first structure is formed on the temporary substrate. The specific method includes: forming a lead-out electrode layer, and patterning the lead-out electrode layer to form a lead-out electrode 201.

[0123] Reference Figure 17 , then a first sacrificial layer 210 and a dielectric layer 101A that surrounds the first sacrificial layer at least on the side thereof are formed. The relevant content in Example 4 can be cited here.

[0124] In this embodiment, the dielectric layer 101A that surrounds the first sacrificial layer at least on the side of the first sacrificial layer also covers the surface of the first sacrificial layer 210. After forming the first structure, it further includes bonding the carrier substrate 100 to the dielectric layer 101A that surrounds the first sacrificial layer at least on the side of the first sacrificial layer.

[0125] Reference Figure 18 , after bonding the carrier substrate 100, flip the formed structure, remove the temporary substrate, and sequentially form the conductive column 401 and the second lead-out portion 402. The method for forming the conductive column 401 and the second lead-out portion 402 refers to Embodiment 4. During the process of forming the second lead-out portion 402, the second passivation layer 102B is also formed. The relevant content in Embodiment 4 can be cited here.

[0126] The method for removing the first sacrificial layer and the second sacrificial layer in Embodiment 4 can be cited in Embodiment 5.

[0127] Variant Example 1 of Embodiment 5

[0128] In Embodiment 5, the piezoelectric layer is never etched, maintaining the integrity of the piezoelectric layer, and the piezoelectric layer is distributed in both the active region and the inactive region. The first gap and the second gap are separated from each other by the piezoelectric layer. Therefore, the first sacrificial layer and the second sacrificial layer are not connected to each other and need to be removed separately.

[0129] In Variant Example 1, after forming the piezoelectric layer or after forming the lead-out electrode, the piezoelectric layer can be patterned to remove the piezoelectric layer in the inactive region or form an air edge gap around the piezoelectric layer in the active resonance region. For the advantages of this case, please refer to the corresponding part in the structural embodiment.

[0130] Correspondingly, in this Variant Example 1, after forming the first sacrificial layer, the second sacrificial layer still exists, and the first sacrificial layer also fills the periphery of the patterned piezoelectric layer. At this time, the first sacrificial layer and the second sacrificial layer are connected to each other, and the first sacrificial layer and the second sacrificial layer can be removed simultaneously.

[0131] Variant Example 2 of Embodiment 5

[0132] In Variant Example 2, after forming the dielectric layer 102A that surrounds the second sacrificial layer at least on the side of the second sacrificial layer and the second sacrificial layer on the temporary substrate, an external electrode and a planar layer are formed on the temporary substrate (the external electrode is not embedded in the second sacrificial layer), and the surface of the external electrode and the planar layer are flush; then, referring to the method of Embodiment 5, a piezoelectric layer is formed. The formation steps and methods of each subsequent structure refer to Embodiment 5.

[0133] In the second modification example, the piezoelectric layer may be located in the effective resonance region and the ineffective region. At this time, the first sacrificial layer and the second sacrificial layer are separated from each other and need to be removed separately.

[0134] In the second modification example, the piezoelectric layer may also be patterned before or after patterning the lead-out electrode layer to remove the piezoelectric layer in the ineffective region or form an air gap around the piezoelectric layer in the effective resonance region. In this case, after forming the first sacrificial layer, the second sacrificial layer still exists, and the first sacrificial layer also fills the periphery of the patterned piezoelectric layer. At this time, the first sacrificial layer and the second sacrificial layer are connected to each other, and the first sacrificial layer and the second sacrificial layer can be removed simultaneously.

[0135] Example 6

[0136] Embodiment 6 of the present invention provides a method for manufacturing a thin film bulk acoustic resonator. Figures 20 to 27 FIG. is a schematic structural diagram corresponding to different steps in the method for manufacturing a thin film bulk acoustic resonator according to Embodiment 6 of the present invention. The following will refer to Figures 20 to 27 for a detailed description of this embodiment.

[0137] Referring to Figure 20 , a carrier substrate 100 is provided, and a second lead-out portion 402 is formed on the carrier substrate 100. The material of the second lead-out portion 402 refers to Embodiment 1, and a conductive material layer can be formed by physical vapor deposition, and then the conductive material layer is patterned to form the second lead-out portion 402. The relevant content in Embodiment 4 can be cited here.

[0138] Referring to Figure 21 and Figure 22 , a dielectric layer 102A and a second sacrificial layer 220 that surround the second sacrificial layer at least on the side thereof are formed. Specifically:

[0139] A dielectric layer 102A that surrounds the second sacrificial layer at least on the side thereof is formed on the outer periphery and above the second lead-out portion 402, and the dielectric layer 102A that surrounds the second sacrificial layer at least on the side thereof is etched to form a second gap 221, so that one end of the second lead-out portion 402 is located in the second gap 221 and the other end is located outside the second gap 221.

[0140] Referring to Figure 22 , the second sacrificial layer 220 is filled in the second gap. The material and formation method of the second sacrificial layer refer to Embodiment 4, and the upper surface of the second sacrificial layer 210 is flush with the upper surface of the dielectric layer 102A that surrounds the second sacrificial layer at least on the side thereof. It is also possible to first form the second sacrificial layer and then form the dielectric layer that surrounds the second sacrificial layer at least on the side thereof. The relevant content in Embodiment 4 can be cited here.

[0141] Continue to refer to Figure 22 In the second sacrificial layer, a conductive pillar 401 is formed, and the lower end of the conductive pillar 401 is connected to the second lead-out portion 402. The relevant N content of the structure, shape, and position of the conductive pillar in Embodiment 4 can be cited here.

[0142] Refer to Figure 23 On the second sacrificial layer 220 and at least on the dielectric layer 102A surrounding the second sacrificial layer on the side of the second sacrificial layer, an external electrode layer is sequentially formed, and the external electrode layer is patterned to form an external electrode 203. In this embodiment, the external electrode 203 is completely located within the region surrounded by the second sacrificial layer. A sacrificial material is formed on the second sacrificial layer outside the external electrode, and the top surface of the newly formed sacrificial material is flush with the top surface of the external electrode. The material and formation method of the external electrode layer refer to Embodiment 4.

[0143] Refer to Figure 24 On the external electrode 203 and the periphery of the external electrode 203, a piezoelectric layer 202 is formed, and a lead-out electrode layer 201' is formed on the upper surface of the piezoelectric layer 202. The materials and formation methods of the lead-out electrode layer 201' and the piezoelectric layer 202 refer to Embodiment 4.

[0144] Refer to Figure 25 The lead-out electrode layer is etched to form a lead-out electrode 201. In this embodiment, a part of the edge of the lead-out electrode 201 is located above the region surrounded by the first sacrificial layer 220, and the other part of the edge extends out of the region where the second sacrificial layer 220 is located. Among them, the lead-out electrode 201 extending out of the region where the second sacrificial layer 220 is located constitutes the first lead-out portion 403. A first sacrificial layer 210 is formed, and the first sacrificial layer 210 covers the surface of the lead-out electrode 201 except for the first lead-out portion 403 and the surface of the piezoelectric layer on the periphery of the lead-out electrode opposite to the first lead-out portion 403. After the first sacrificial layer is released in the later process, a first gap is formed. In this embodiment, the first sacrificial layer and the second sacrificial layer are almost oppositely arranged.

[0145] Refer to Figure 26 On the periphery of the first sacrificial layer 210, a dielectric layer 101A that surrounds the first sacrificial layer at least on the side of the first sacrificial layer is formed.

[0146] Refer to Figure 27 The first sacrificial layer and the second sacrificial layer are removed to form a first gap 211 and a second gap 221. A communication hole can be formed in the piezoelectric layer outside the external electrode to connect the first sacrificial layer and the second sacrificial layer, and a release hole is formed on the second dielectric layer 102 above the second sacrificial layer. The first sacrificial layer and the second sacrificial layer are removed at one time through the through-hole release hole. In other embodiments, the first sacrificial layer can also be removed first and then the second sacrificial layer.

[0147] Variant Example 1 of Embodiment 6

[0148] In Embodiment 6, the piezoelectric layer is never etched, the integrity of the piezoelectric layer is retained, and the piezoelectric layer is distributed in both the active region and the inactive region. The first gap and the second gap are separated from each other by the piezoelectric layer. Therefore, the first sacrificial layer and the second sacrificial layer are not connected to each other and need to be removed separately.

[0149] In Variant Embodiment 1, after forming the piezoelectric layer or after leading out the electrodes, the piezoelectric layer can be patterned to remove the piezoelectric layer in the inactive region or to form an air gap around the piezoelectric layer in the active resonance region. For the advantages of this case, please refer to the corresponding part in the structural embodiment.

[0150] Correspondingly, in this Variant Embodiment 1, after forming the first sacrificial layer, the second sacrificial layer still exists, and the first sacrificial layer also fills the periphery of the patterned piezoelectric layer. At this time, the first sacrificial layer and the second sacrificial layer are connected to each other, and the first sacrificial layer and the second sacrificial layer can be removed simultaneously.

[0151] Example 7

[0152] Embodiment 7 of the present invention provides a method for manufacturing a thin film bulk acoustic resonator. Figures 28 to 33 is a schematic structural diagram corresponding to different steps in the method for manufacturing a thin film bulk acoustic resonator according to Embodiment 7 of the present invention. The following will refer to Figures 28 to 33 to describe this embodiment in detail.

[0153] In this embodiment, the external electrode is located below the lead-out electrode, and a second structure, a conductive column, a second lead-out portion, and a first structure are sequentially formed.

[0154] Refer to Figure 28 , a temporary substrate 200 is provided, and a lead-out electrode layer 201', a piezoelectric layer 202, and an external electrode layer 203' are formed on the temporary substrate 200. The content of Embodiment 4 can be cited here.

[0155] Refer to Figure 29 , after forming the external electrode layer 203', the external electrode layer 203' is patterned to form an external electrode 203. A second sacrificial layer material is formed to cover the external electrode 203 and the piezoelectric layer 202. The second sacrificial material is patterned to form a second sacrificial layer 220. In this embodiment, the second sacrificial layer 220 covers the surface and the outer periphery of the external electrode 203.

[0156] Refer to Figure 30 , a dielectric layer 102A is formed to surround the second sacrificial layer at least on the side of the second sacrificial layer, covering the piezoelectric layer 202 on the outer periphery of the second sacrificial layer 220. In this embodiment, the upper surface of the second sacrificial layer 220 is also covered.

[0157] Reference Figure 31 , a conductive column 401 is formed on the surface of the external electrode, the second sacrificial layer is removed to form a second gap, and a second lead-out portion 402 and a second passivation layer 102B are formed above the conductive column 401.

[0158] Reference Figure 32 , in this embodiment, it further includes forming a carrier substrate 100 on the surface of the second passivation layer 102B. The temporary substrate is removed, and the lead-out electrode layer is patterned to form a lead-out electrode 201.

[0159] Reference Figure 33 , a first sacrificial layer material is formed to cover the lead-out electrode 201 and the piezoelectric layer 202. The first sacrificial material is patterned to form a first sacrificial layer. In this embodiment, the first sacrificial layer covers a part of the lead-out electrode 201 and the piezoelectric layer outside the periphery of the lead-out electrode 210, covering the edges of a part of the lead-out electrode. The part of the lead-out electrode not covered by the first sacrificial layer constitutes a first lead-out portion for connecting to an external electrical signal. A dielectric layer 101A is formed to surround the first sacrificial layer at least on the side of the first sacrificial layer, covering the first sacrificial layer and the lead-out electrode 201 and the piezoelectric layer 202 outside the periphery of the first sacrificial layer, and then the first sacrificial layer is removed.

[0160] In this embodiment, the piezoelectric layer is never etched, maintaining the integrity of the piezoelectric layer, and the piezoelectric layer is distributed in both the effective area and the ineffective area. The first gap and the second gap are separated from each other by the piezoelectric layer. Therefore, the first sacrificial layer and the second sacrificial layer are not connected to each other and need to be removed separately.

[0161] In another embodiment, after forming the external electrode or the lead-out electrode, the piezoelectric layer can be patterned to remove the piezoelectric layer in the ineffective area or form an air edge gap around the piezoelectric layer in the effective resonance area. For the advantages of this case, please refer to the corresponding part in the structural embodiment.

[0162] Correspondingly, after forming the first sacrificial layer, the second sacrificial layer still exists, and the first sacrificial layer also fills the periphery of the patterned piezoelectric layer. At this time, the first sacrificial layer and the second sacrificial layer are connected to each other, and the first sacrificial layer and the second sacrificial layer can be removed simultaneously.

[0163] It should be noted that each embodiment in this specification is described in a related manner. The same or similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the method embodiments, since they are basically similar to the structural embodiments, the description is relatively simple, and the related parts can refer to the partial description of the structural embodiments. For the component structure, positional relationship, formation method, etc. in Embodiment 5, Embodiment 6, and Embodiment 7, refer to the related description in Embodiment 4.

[0164] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention based on the above disclosure fall within the scope of protection of the claims.

Claims

1. A thin film bulk acoustic wave resonator, characterized in that, Comprising: Stacked lead-out electrodes, a piezoelectric layer, and an external electrode. The effective resonance region includes the region where the lead-out electrodes, the piezoelectric layer, and the external electrode overlap with each other in the direction perpendicular to the surface of the piezoelectric layer. The outside of the effective resonance region is an ineffective region; A first dielectric layer, with a first gap provided between the surface of the first dielectric layer and the surface of the lead-out electrode; The part of the lead-out electrode extending out of the first gap from the effective resonance region is a first lead-out portion; A second dielectric layer, with a second gap provided between the surface of the second dielectric layer and the surface of the external electrode; The external electrode is located within the region surrounded by the second gap or their boundaries coincide; A conductive post, with one end connected to the external electrode and the other end connected to a second lead-out portion, and the second lead-out portion extends out of the second gap from the effective resonance region; One of the lead-out electrode and the external electrode is located above the other; The piezoelectric layer includes a resonance portion and an overlapping portion located on the periphery of the resonance portion. At least part of the resonance portion is located in the effective resonance region, the overlapping portion is located outside the effective resonance region, and the resonance portion is in contact with or separated from the overlapping portion; The two side surfaces of the piezoelectric layer located at the overlapping portion are respectively in contact with the surfaces of the first dielectric layer and the second dielectric layer; The conductive post is provided at the boundary of the effective resonance region; The conductive post is provided at the boundary of the second gap, or there is a distance between the conductive post and the boundary of the second gap, or part of the conductive post is provided at the boundary of the second gap and the other part of the conductive post has a distance from the boundary of the second gap; The projection of the conductive post in the direction of the piezoelectric layer is a closed or discontinuous ring; The second lead-out portion is buried in the second dielectric layer; Outside the effective resonance region, the projections of the second lead-out portion and the first lead-out portion in the direction of the piezoelectric layer are staggered from each other.

2. The thin film bulk acoustic wave resonator according to claim 1, wherein The boundaries of the projections of the first gap and the second gap in the direction of the piezoelectric layer surround the boundary of the projection of the effective resonance region in the direction of the piezoelectric layer.

3. The thin film bulk acoustic resonator according to claim 1, wherein The first gap and the second gap are connected to each other, or the first gap and the second gap are isolated from each other.

4. The thin film bulk acoustic resonator according to claim 1, characterized in that, The first gap and the second gap are connected through a plurality of through holes distributed in the ineffective region; Or, the first gap and the second gap are connected through a non-closed annular through hole surrounding part of the effective resonance region.

5. The thin film bulk acoustic resonator according to claim 1, wherein The piezoelectric layer extends out of the first gap and the second gap from the effective resonance region; Or, the piezoelectric layer is located in the effective resonance region, and further includes a flat layer of the same layer as the piezoelectric layer, and the flat layer extends around the piezoelectric layer to outside the gap; Or, the piezoelectric layer is only located in the effective resonance region.

6. The thin film bulk acoustic wave resonator according to claim 1, characterized in that, The overlapping portion and the resonance portion are in contact with each other, and the piezoelectric layer is a complete film layer.

7. The thin film bulk acoustic wave resonator according to claim 1, characterized in that, The overlapping portion and the resonance portion are separated from each other, the first gap and the second gap are connected into a cavity, and the periphery of the resonance portion is exposed in the cavity.

8. The thin film bulk acoustic resonator according to claim 1, wherein The material of the conductive post or the second lead-out portion includes: gold, silver, tungsten, platinum, aluminum, or copper.

9. A method for manufacturing a thin film bulk acoustic resonator according to any one of claims 1, 2, 5, and 8, characterized in that, Comprising: Form a first structure, the first structure comprising: a lead-out electrode, a first sacrificial layer covering at least the lead-out electrode and avoiding the region where the first lead-out portion is located, and a dielectric layer surrounding the first sacrificial layer at least on the side of the first sacrificial layer; Form a piezoelectric layer; Form a second structure, the second structure comprising: an external connection electrode, a second sacrificial layer covering at least the external connection electrode, and a dielectric layer surrounding the second sacrificial layer at least on the side of the second sacrificial layer; Form a conductive pillar, penetrating the second sacrificial layer and connecting the external connection electrode; Form a second lead-out portion, with one end connected to the conductive pillar and the other end extending out of the effective resonance region; remove the first sacrificial layer and the second sacrificial layer to form the first gap and the second gap.

10. The manufacturing method of the thin film bulk acoustic resonator according to claim 9, characterized in that, The manufacturing method includes: Provide a temporary substrate; Form the first structure on the temporary substrate; Bond a carrier substrate on the first structure and remove the temporary substrate; Form the second structure, the conductive pillar, and the second lead-out portion on the carrier substrate in sequence.

11. The manufacturing method of the thin film bulk acoustic resonator according to claim 9, characterized in that, The manufacturing method includes: Provide a temporary substrate; Form the second structure on the temporary substrate; Form a piezoelectric layer to cover the second structure; Form the first structure on the piezoelectric layer; Bond a carrier substrate on the first structure, remove the temporary substrate, and form the conductive pillar and the second lead-out portion.

12. The manufacturing method of the thin film bulk acoustic resonator according to claim 9, characterized in that, The manufacturing method includes: Provide a carrier substrate; Form the second lead-out portion on the carrier substrate, and then form the conductive pillar and the second structure; Form a piezoelectric layer to cover the second structure; Form the first structure on the second structure.

13. The manufacturing method of the thin film bulk acoustic resonator according to claim 9, characterized in that, The manufacturing method includes: Provide a temporary substrate; Form the second structure, the conductive pillar, and the second lead-out portion on the temporary substrate in sequence; Bond a carrier substrate on the side where the second lead-out portion is located and remove the temporary substrate; Form the first structure on the carrier substrate.

14. The manufacturing method of a thin film bulk acoustic wave resonator according to any one of claims 10-13, characterized in that Form an external connection electrode layer, a piezoelectric layer, and a lead-out electrode layer in sequence; Pattern the lead-out electrode layer to form the lead-out electrode; After forming the first structure, pattern the external connection electrode layer to form an external connection electrode; Preserve the integrity of the piezoelectric layer, and the first gap and the second gap are separated from each other by the piezoelectric layer; Or, Form an external connection electrode layer, a piezoelectric layer, and a lead-out electrode layer in sequence; Pattern the lead-out electrode layer to form the lead-out electrode; After forming the first structure, pattern the external connection electrode layer to form an external connection electrode; After patterning the lead-out electrode or after patterning the external connection electrode, pattern the piezoelectric layer to remove the piezoelectric layer in the invalid region or form an air edge gap around the piezoelectric layer in the effective resonance region; Or, Form a lead-out electrode layer, a piezoelectric layer, and an external connection electrode layer; Pattern the lead-out electrode layer, the piezoelectric layer, and the external connection electrode layer, and remove the portions of the lead-out electrode layer, the piezoelectric layer, and the external connection electrode layer located in the invalid region to form the lead-out electrode, the external connection electrode, and the piezoelectric layer; After that, the first sacrificial layer and the first dielectric layer are formed, and the first sacrificial layer covers the top surface and side surfaces of the lead-out electrode, the external electrode, and the piezoelectric layer; Or, A lead-out electrode layer, a piezoelectric layer, and an external electrode layer are formed; The lead-out electrode layer is patterned to form the lead-out electrode; After that, the first sacrificial layer and the dielectric layer that at least surrounds the first sacrificial layer on the side of the first sacrificial layer are formed, and the first sacrificial layer covers the top surface and side surfaces of the lead-out electrode, the external electrode, and the piezoelectric layer; After patterning the lead-out electrode or after patterning the external electrode, the piezoelectric layer is patterned to remove the piezoelectric layer in the invalid area or to form an air gap around the piezoelectric layer in the effective resonance area; Or, A lead-out electrode and a planar layer are formed, and the lead-out electrode is flush with the surface of the planar layer; A piezoelectric layer is formed on the flush surface; An external electrode layer is formed on the piezoelectric layer; The external electrode layer is patterned to form the external electrode; Before or after patterning the external electrode layer, the piezoelectric layer is patterned to remove the piezoelectric layer in the invalid area or to form an air gap around the piezoelectric layer in the effective resonance area.

15. The manufacturing method of the thin film bulk acoustic resonator according to claim 9, characterized in that, The method for forming the second structure includes: An external electrode layer is formed, and the external electrode layer is patterned to form the external electrode; A second sacrificial layer is formed, and the second sacrificial layer only covers the top surface of the external electrode or covers the top surface and side surfaces of the external electrode; A dielectric layer that at least surrounds the second sacrificial layer on the side of the second sacrificial layer is formed, covering the side surface of the second sacrificial layer and the side surface of the external electrode or covering the side surface, top surface of the second sacrificial layer and the side surface of the external electrode; Or, An external electrode layer is formed, and the external electrode layer is patterned to form the external electrode; A dielectric layer that at least surrounds the second sacrificial layer on the side of the second sacrificial layer is formed, covering the external electrode and the surrounding area; The dielectric layer that at least surrounds the second sacrificial layer on the side of the second sacrificial layer is etched to form a second gap, and the second sacrificial layer is formed in the second gap.

16. The manufacturing method of the thin film bulk acoustic resonator according to claim 9, characterized in that The method for forming the conductive column includes: The film layer between the external electrode and the second lead-out portion is patterned to form a through hole; The through hole is filled with a conductive material to form the conductive column.

17. The manufacturing method of the thin film bulk acoustic resonator according to claim 9, characterized in that, The method for forming the second lead-out portion includes: A second passivation layer is formed; The second passivation layer is etched to form a groove; A conductive material layer is formed in the groove as the second lead-out portion; Or, A conductive material layer is formed, and the conductive material layer is patterned to form the second lead-out portion; A second passivation layer is formed to cover the second lead-out portion; The dielectric layer that at least surrounds the second sacrificial layer on the side of the second sacrificial layer includes the second passivation layer.

18. The manufacturing method of the thin film bulk acoustic resonator according to claim 9, characterized in that, The method for forming the first structure includes: A lead-out electrode layer is formed, and the lead-out electrode layer is patterned to form the lead-out electrode; A first sacrificial layer is formed, and the first sacrificial layer at least covers the lead-out electrode and avoids the area of the first lead-out portion; A dielectric layer that at least surrounds the first sacrificial layer on the side of the first sacrificial layer is formed, covering the side surface of the first sacrificial layer or covering the side surface, top surface of the first sacrificial layer and the side surface of the lead-out electrode; Or, Form an extraction electrode layer and pattern the extraction electrode layer to form the extraction electrode; Form a dielectric layer that surrounds the first sacrificial layer at least on the side of the first sacrificial layer, covering the extraction electrode and the surrounding area; Etch the dielectric layer that surrounds the first sacrificial layer at least on the side of the first sacrificial layer to form a first gap above the extraction electrode other than the first extraction portion, and form the first sacrificial layer in the first gap.

19. The manufacturing method of the thin film bulk acoustic resonator according to claim 9, characterized in that, The first sacrificial layer is formed before the second sacrificial layer. Removing the first sacrificial layer and the second sacrificial layer includes: Removing the first sacrificial layer before forming the second sacrificial layer or removing the first sacrificial layer and the second sacrificial layer after forming the second sacrificial layer; Or, The first sacrificial layer is formed after the second sacrificial layer. Removing the first sacrificial layer and the second sacrificial layer includes: Removing the second sacrificial layer before forming the first sacrificial layer or removing the first sacrificial layer and the second sacrificial layer after forming the first sacrificial layer.

20. The manufacturing method of the thin film bulk acoustic resonator according to claim 9, characterized in that, The material of the first sacrificial layer or the second sacrificial layer includes: phosphosilicate glass, low-temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide or photoresist.

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