Filter and method for forming the same, and electronic device

Abstract

A filter and a forming method thereof, and an electronic device, the filter comprising: a piezoelectric layer comprising a first side and a second side arranged oppositely, a first electrode located on the first side, and a second electrode located on the second side, the piezoelectric layer comprising a plurality of resonant units in a direction perpendicular to a thickness direction of the piezoelectric layer structure; and a heat dissipation structure located at a boundary between adjacent resonant units and in contact with any one of the first electrode and the second electrode, or the heat dissipation structure is in contact with the first electrode and the second electrode, respectively. By arranging the heat dissipation structure at the boundary between the adjacent resonant units, heat generated by vibration of the piezoelectric layer can be effectively promoted to conduct laterally along the extension direction of the piezoelectric layer, the heat conduction effect of the heat conduction path of the resonant unit away from the edge position of the piezoelectric layer structure is enhanced, thereby improving the heat dissipation efficiency of the filter, and further improving the performance and reliability of the filter.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing, and more particularly to a filter, a method for forming the same, and an electronic device. Background Technology

[0002] Since the development of analog radio frequency (RF) communication technology, RF front-end modules have gradually become core components of communication equipment. Among all RF front-end modules, filters have become the fastest-growing and most promising component. With the rapid development of wireless communication technology, the market has also placed more stringent standards on the performance of RF filters in various aspects. Among existing filters, thin-film bulk acoustic resonators (FBARs) are widely used due to their small size, low insertion loss, high out-of-band rejection, high quality factor, high operating frequency, large power capacity, and good ESD resistance.

[0003] Among numerous radio frequency filters, thin-film bulk acoustic resonators (FBARs) are widely used due to their small size, low insertion loss, high out-of-band rejection, high quality factor, high operating frequency, large power capacity, and good ESD resistance. The working principle of a FBAR is based on the vibration of a piezoelectric thin film layer under an alternating electric field, which excites bulk acoustic waves propagating along the thickness of the piezoelectric thin film layer, forming standing wave oscillations, thereby achieving selective signal filtering.

[0004] However, the heat dissipation performance of the filters still needs to be improved. Summary of the Invention

[0005] The problem addressed by the embodiments of this disclosure is to provide a filter and a method for forming the same, as well as an electronic device, which is beneficial for improving the heat dissipation efficiency of the filter.

[0006] To address the aforementioned problems, this disclosure provides a filter comprising: a piezoelectric stacked structure including a first electrode, a piezoelectric layer, and a second electrode stacked together, the piezoelectric layer including a first side and a second side disposed opposite to each other, the first electrode located on the first side, the second electrode located on the second side, and the piezoelectric stacked structure including a plurality of resonant units along a plane perpendicular to the thickness direction of the piezoelectric stacked structure; and a heat dissipation structure located at the junction of adjacent resonant units, and the heat dissipation structure being in contact with either the first electrode or the second electrode, or the heat dissipation structure being in contact with both the first electrode and the second electrode.

[0007] Accordingly, this disclosure also provides a method for forming a filter, comprising: providing a piezoelectric stack structure, the piezoelectric stack structure including a first electrode, a piezoelectric layer and a second electrode stacked thereon, the piezoelectric layer including a first side and a second side disposed opposite to each other, the first electrode being located on the first side and the second electrode being located on the second side, the piezoelectric stack structure including a plurality of resonant units along a plane direction perpendicular to the thickness direction of the piezoelectric stack structure; forming a heat dissipation structure at the junction of adjacent resonant units, the heat dissipation structure being in contact with either the first electrode or the second electrode, or the heat dissipation structure being in contact with both the first electrode and the second electrode.

[0008] Accordingly, this disclosure also provides an electronic device, including: the filter described in any embodiment of this disclosure.

[0009] Compared with the prior art, the technical solution of the present disclosure has the following advantages:

[0010] This disclosure provides a filter, including: a piezoelectric stacked structure, comprising a first electrode, a piezoelectric layer, and a second electrode stacked together, the piezoelectric layer including a first side and a second side disposed opposite to each other, the first electrode located on the first side, the second electrode located on the second side, and the piezoelectric stacked structure including a plurality of resonant units along a plane direction perpendicular to the thickness direction of the piezoelectric stacked structure; and a heat dissipation structure located at the junction of adjacent resonant units, and the heat dissipation structure being in contact with either the first electrode or the second electrode, or the heat dissipation structure being in contact with both the first electrode and the second electrode. In this disclosure, by providing a heat dissipation structure at the junction of adjacent resonant units, the heat generated by the vibration of the piezoelectric layer in the resonant units can be effectively promoted to be quickly conducted laterally along the extension direction of the piezoelectric layer, enhancing the heat conduction effect of the heat conduction path of the resonant units far from the edge of the piezoelectric stacked structure, thereby improving the heat dissipation efficiency of the filter, and thus improving the performance and reliability of the filter.

[0011] This disclosure also provides a method for forming a filter, comprising: providing a piezoelectric stack structure, the piezoelectric stack structure including a first electrode, a piezoelectric layer, and a second electrode stacked together, the piezoelectric layer including a first side and a second side disposed opposite to each other, the first electrode being located on the first side, the second electrode being located on the second side, and the piezoelectric stack structure including a plurality of resonant units along a plane direction perpendicular to the thickness direction of the piezoelectric stack structure; forming a heat dissipation structure at the junction of adjacent resonant units, the heat dissipation structure being in contact with either the first electrode or the second electrode, or the heat dissipation structure being in contact with both the first electrode and the second electrode; in some embodiments, by providing a heat dissipation structure at the junction of adjacent resonant units, the heat generated by the vibration of the piezoelectric layer in the resonant units can be effectively promoted to be quickly conducted laterally along the extension direction of the piezoelectric layer, enhancing the heat conduction effect of the heat conduction path of the resonant units far from the edge of the piezoelectric stack structure, thereby improving the heat dissipation efficiency of the filter, and thus improving the performance and reliability of the filter. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of a filter structure;

[0013] Figure 2 This is a schematic diagram of the structure of an embodiment of the filter disclosed herein;

[0014] Figures 3 to 14 This is a schematic diagram of the structure corresponding to each step in one embodiment of the filter formation method disclosed herein. Detailed Implementation

[0015] As the background technology shows, the heat dissipation performance of filters still needs improvement. This paper analyzes the reasons why the heat dissipation performance of filters still needs improvement, using a schematic diagram of a filter structure as an example.

[0016] Figure 1 This is a schematic diagram of a filter structure.

[0017] refer to Figure 1The filter includes: a piezoelectric stack structure 10, comprising a first electrode 11, a piezoelectric layer 12, and a second electrode 13 stacked together; the piezoelectric layer 12 includes a first side 14 and a second side 15 disposed opposite to each other; the first electrode 11 is located on the first side 14; the second electrode 13 is located on the second side 15; and along a plane perpendicular to the thickness direction of the piezoelectric stack structure 10, the piezoelectric stack structure 10 includes a plurality of resonant units i; and a first support layer 16 located on the surface of the second electrode 13 facing away from the piezoelectric layer 12. On the surface, and at the edge of the piezoelectric stacked structure 10 and the junction of the adjacent resonant unit i, the first support layer 16 and the piezoelectric stacked structure 10 form a first cavity 17; a first substrate 18 is located on the side of the first support layer 16 away from the piezoelectric layer 12, and the first substrate 18 seals the first cavity 17; at the edge of the piezoelectric stacked structure 10, a signal electrode 19 is formed that penetrates the first support layer 16 and the first substrate 18, and the signal electrode 19 is in contact with the second electrode 13.

[0018] Typically, the first support layer 16 is made of silicon dioxide. For some resonant units i, especially those not directly connected to the signal electrode 19 (such as...), Figure 1 (The part marked with a dashed box in the image) The heat generated during operation first needs to pass through the piezoelectric stack structure 10 of other resonant units i, then through the first support layer 16, and finally through the signal electrode 19 to be conducted away (e.g., Figure 1 The heat conduction paths 1 and 4 shown in the diagram); or first through the first support layer 16, then through the first substrate 18, and finally through the signal electrode 19 (as shown in the diagram). Figure 1 The heat conduction paths 2 and 3 shown in the diagram are ineffective due to the poor thermal conductivity of silicon dioxide. This can easily lead to heat accumulation in the resonator, which in turn affects the performance and reliability of the filter.

[0019] To address the aforementioned technical problems, this disclosure provides a filter comprising: a piezoelectric stacked structure, including a first electrode, a piezoelectric layer, and a second electrode stacked together, the piezoelectric layer including a first side and a second side disposed opposite to each other, the first electrode located on the first side, the second electrode located on the second side, and the piezoelectric stacked structure including a plurality of resonant units along a plane perpendicular to the thickness direction of the piezoelectric stacked structure; and a heat dissipation structure located at the junction of adjacent resonant units, and the heat dissipation structure being in contact with either the first electrode or the second electrode, or the heat dissipation structure being in contact with both the first electrode and the second electrode.

[0020] In the scheme disclosed in this embodiment, by setting a heat dissipation structure at the junction of adjacent resonant units, the heat generated by the vibration of the piezoelectric layer of the resonant unit can be effectively promoted to be quickly conducted laterally along the extension direction of the piezoelectric layer, thereby enhancing the heat conduction effect of the heat conduction path of the resonant unit far from the edge of the piezoelectric stack structure, thereby improving the heat dissipation efficiency of the filter, and thus improving the performance and reliability of the filter.

[0021] To make the above-mentioned objects, features and advantages of this disclosure more apparent and understandable, specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings.

[0022] Figure 2 This is a schematic diagram of the structure of the first embodiment of the filter disclosed herein.

[0023] refer to Figure 2 The filter includes: a piezoelectric stack structure 100, comprising a first electrode 101, a piezoelectric layer 102, and a second electrode 103 stacked together; the piezoelectric layer 102 includes a first side 104 and a second side 105 disposed opposite to each other; the first electrode 101 is located on the first side 104; the second electrode 103 is located on the second side 105; and along a plane perpendicular to the thickness direction of the piezoelectric stack structure 100, the piezoelectric stack structure 100 includes a plurality of resonant units i'; and a heat dissipation structure 107 located at the junction of adjacent resonant units i', and the heat dissipation structure 107 is in contact with either the first electrode 101 or the second electrode 103, or the heat dissipation structure 107 is in contact with both the first electrode 101 and the second electrode 103.

[0024] The piezoelectric stack structure 100 is used to prepare for the subsequent formation of a filter. The corresponding piezoelectric stack structure 100 is used to realize the mutual conversion between electrical signals and acoustic signals, so that the filter can filter the signals.

[0025] The first electrode 101 and the second electrode 103 are both made of conductive materials. The conductive materials can be metallic materials with conductive properties, such as one or more of the following: molybdenum (Mo), aluminum (Al), copper (Cu), platinum (Pt), gold (Au), iridium (Ir), osmium (Os), rhenium (Re), palladium (Pd), rhodium (Rh), ruthenium (Ru), and tungsten (W).

[0026] It is understood that in other embodiments, the materials of the first electrode and the second electrode may also be other electrode materials suitable for forming a piezoelectric stack structure.

[0027] The piezoelectric layer 102 can be made of piezoelectric crystals, piezoelectric ceramics, or piezoelectric polymers. Specifically, the piezoelectric crystal can be aluminum nitride, lead zirconate titanate, quartz crystal, lithium gallium oxide, lithium germanate, titanium germanate, lithium niobate, or lithium tantalate, etc., and the piezoelectric polymer can be polyvinylidene fluoride, vinylidene fluoride-trifluoroethylene copolymer, nylon-11, or vinylidene dicyanide-vinyl acetate alternating copolymer, etc. In some embodiments, the piezoelectric layer 102 is made of aluminum nitride.

[0028] The first side 104 is used to provide a process platform for forming the first electrode 101; the second side 105 is used to provide a process platform for forming the second electrode 103.

[0029] It should be noted that the first electrode 101 is located on the first side 104, and the second electrode 103 is located on the second side 105. When an electrical signal from an external circuit is applied to the second electrode 103 at the edge of the piezoelectric stack structure 100, an electric field is generated between the first electrode 101 and the second electrode 103 at the edge of the piezoelectric stack structure 100. This electric field acts on the piezoelectric layer 102, causing the piezoelectric layer 102 to produce a piezoelectric effect. Consequently, the piezoelectric layer 102 generates mechanical vibration and generates an electrical signal in the opposite direction. Since the first electrode 101 or the second electrode 103 at the junction of adjacent resonant units i' is connected to the first electrode 101 or the second electrode 103 at the edge, the electrical signal generated by the piezoelectric layer 102 can be transmitted through the first electrode 101 or the second electrode 103 at the edge to the first electrode 101 or the second electrode 103 at the junction of adjacent resonant units i', thereby realizing the cross-unit transmission of the electrical signal.

[0030] The heat dissipation structure 107 is used to facilitate the rapid transverse conduction of the heat generated by the vibration of the piezoelectric layer 102 in the resonant unit i' along the extension direction of the piezoelectric layer 102.

[0031] It should be noted that by setting a heat dissipation structure 107 at the junction of adjacent resonant units i', the heat generated by the vibration of the piezoelectric layer 102 in the resonant unit i' can be effectively promoted to be quickly conducted laterally along the extension direction of the piezoelectric layer 102. This enhances the heat conduction effect of the heat conduction path of the resonant unit i' located away from the edge of the piezoelectric stack structure 100, thereby improving the heat dissipation efficiency of the filter and thus improving the performance and reliability of the filter.

[0032] The heat dissipation structure 107 includes one or both of a first heat dissipation structure 110 and a second heat dissipation structure 111; wherein, the first heat dissipation structure 110 is located on the first electrode 101 or the second electrode 103 on either side of the piezoelectric layer 102, and the first heat dissipation structure 110 is in contact with the first electrode 101 or the second electrode 103 located on the same side of the piezoelectric layer 102; the second heat dissipation structure 111 penetrates the piezoelectric layer 102 from either side of the piezoelectric layer 102, and is in contact with the surface of the second electrode 103 or the first electrode 101 on the other side of the piezoelectric layer 102 facing the piezoelectric layer 102.

[0033] In some embodiments, when the heat dissipation structure 107 includes a first heat dissipation structure 110, the material of the first heat dissipation structure 110 includes one or more of metallic materials, silicon carbide, diamond, and graphene.

[0034] It should be noted that metallic materials, silicon carbide, diamond, and graphene all have good thermal conductivity, which can quickly conduct the heat generated by the vibration of the piezoelectric layer 102 in the resonant unit i' laterally along the extension direction of the piezoelectric layer 102.

[0035] As an example, when the heat dissipation structure 107 includes a first heat dissipation structure 110, the material of the first heat dissipation structure 110 is a metallic material.

[0036] Specifically, the metallic material includes one or more of aluminum, titanium copper, molybdenum, tungsten, and gold. Aluminum, titanium copper, molybdenum, tungsten, and gold all have high thermal conductivity, thus they can rapidly conduct the heat generated by the vibration of the piezoelectric layer 102 in the resonant unit i' laterally along the extension direction of the piezoelectric layer 102.

[0037] The first heat dissipation structure 110 is located on the first electrode 101 or the second electrode 103 on either side of the piezoelectric layer 102. On the one hand, it conducts the heat generated by the piezoelectric layer 102 during operation from the first electrode 101 or the second electrode 103 to the first heat dissipation structure 110, thereby achieving the heat dissipation function. On the other hand, the first heat dissipation structure 110 is located on the first electrode 101 or the second electrode 103, which helps to increase the thickness of the electrode layer at the junction of adjacent resonant units i', thereby reducing the resistance value at the junction of adjacent resonant units i'.

[0038] The second heat dissipation structure 111 penetrates the piezoelectric layer 102 from either side and contacts the surface of the second electrode 103 or the first electrode 101 on the other side of the piezoelectric layer 102 facing the piezoelectric layer 102. This enables rapid heat conduction between the two sides of the piezoelectric layer 102 and prevents heat from accumulating inside the piezoelectric layer 102.

[0039] Specifically, the heat dissipation structure 107 may include only the first heat dissipation structure 110, or the heat dissipation structure 107 may include only the second heat dissipation structure 111, or the heat dissipation structure 107 may include both the first heat dissipation structure 110 and the second heat dissipation structure 111.

[0040] More specifically, when the heat dissipation structure 107 includes only the first heat dissipation structure 110, the first heat dissipation structure 110 is located on the first electrode 101 on the first side 104 of the piezoelectric layer 102; or, the first heat dissipation structure 110 is located on the second electrode 103 on the second side 105 of the piezoelectric layer 102; or, the first heat dissipation structure 110 is located on the first electrode 101 and the second electrode 103 on both sides of the piezoelectric layer 102.

[0041] When the heat dissipation structure 107 includes only the second heat dissipation structure 111, the second heat dissipation structure 111 extends through the piezoelectric layer 102 from the first side 104 of the piezoelectric layer 102 and contacts the surface of the second electrode 103 on the second side 105 of the piezoelectric layer 102 facing the surface of the piezoelectric layer 102; or, the second heat dissipation structure 111 extends through the piezoelectric layer 102 from the second side 105 of the piezoelectric layer 102 and contacts the surface of the first electrode 101 on the first side 104 of the piezoelectric layer 102 facing the surface of the piezoelectric layer 102; or, the second heat dissipation structure 111 extends through the piezoelectric layer 102 from both sides and contacts the surfaces of the second electrode 103 and the first electrode 101 on the piezoelectric layer 102 facing the surface of the piezoelectric layer 102, respectively.

[0042] When the heat dissipation structure 107 includes a first heat dissipation structure 110 and a second heat dissipation structure 111, the first heat dissipation structure 110 is located on the first electrode 101 on the first side 104 of the piezoelectric layer 102, and the second heat dissipation structure 111 extends from the first side 104 of the piezoelectric layer 102 through the piezoelectric layer 102 and contacts the second electrode 103 on the second side 105 of the piezoelectric layer 102 facing the surface of the piezoelectric layer 102; or, the first heat dissipation structure 110 is located on the first electrode 101 on the first side 104 of the piezoelectric layer 102, and the second heat dissipation structure 111 extends from the second side 104 of the piezoelectric layer 102 through the first electrode 101 on the first side 104 of the piezoelectric layer 102. 05 penetrates the piezoelectric layer 102 and contacts the surface of the first electrode 101 on the first side 104 of the piezoelectric layer 102 facing the piezoelectric layer 102; or, the first heat dissipation structure 110 is located on the first electrode 101 on the first side 104 of the piezoelectric layer 102, and the second heat dissipation structure 111 penetrates the piezoelectric layer 102 from both sides, respectively contacting the surfaces of the second electrode 103 and the first electrode 101 on the piezoelectric layer 102 facing the piezoelectric layer 102; or, the first heat dissipation structure 110 is located on the second electrode 103 on the second side 105 of the piezoelectric layer 102, and the second... A heat dissipation structure 111 extends through the piezoelectric layer 102 from its first side 104 and contacts the surface of the piezoelectric layer 102 with the second electrode 103 on its second side 105 facing the piezoelectric layer 102; or, a first heat dissipation structure 110 is located on the second electrode 103 on the second side 105 of the piezoelectric layer 102, and a second heat dissipation structure 111 extends through the piezoelectric layer 102 from its second side 105 and contacts the surface of the piezoelectric layer 102 with the first electrode 101 on its first side 104 facing the piezoelectric layer 102; or, a first heat dissipation structure 110 is located on the second side of the piezoelectric layer 102. On the second electrode 103 of 105, a second heat dissipation structure 111 extends through the piezoelectric layer 102 from both sides and contacts the surfaces of the second electrode 103 and the first electrode 101 of the piezoelectric layer 102 facing the piezoelectric layer 102, respectively; or, the first heat dissipation structure 110 is located on the first electrode 101 and the second electrode 103 on both sides of the piezoelectric layer 102, and the second heat dissipation structure 111 extends through the piezoelectric layer 102 from the first side 104 and contacts the surface of the second electrode 103 of the second side 105 of the piezoelectric layer 102 facing the piezoelectric layer 102;Alternatively, the first heat dissipation structure 110 is located on the first electrode 101 and the second electrode 103 on both sides of the piezoelectric layer 102, and the second heat dissipation structure 111 penetrates the piezoelectric layer 102 from the second side 105 and contacts the surface of the first electrode 101 on the first side 104 of the piezoelectric layer 102 facing the piezoelectric layer 102; or, the first heat dissipation structure 110 is located on the first electrode 101 and the second electrode 103 on both sides of the piezoelectric layer 102, and the second heat dissipation structure 111 penetrates the piezoelectric layer 102 from both sides and contacts the surfaces of the second electrode 103 and the first electrode 101 on the piezoelectric layer 102 facing the piezoelectric layer 102, respectively.

[0043] As an example, in the case where the heat dissipation structure 107 includes a first heat dissipation structure 110 and a second heat dissipation structure 111, the first heat dissipation structure 110 is located on the first electrode 101 on the first side 104 of the piezoelectric layer 102, and the second heat dissipation structure 111 extends through the first side 104 of the piezoelectric layer 102 and contacts the second electrode 103 on the second side 105 of the piezoelectric layer 102 facing the surface of the piezoelectric layer 102.

[0044] In some embodiments, when the heat dissipation structure 107 includes the second heat dissipation structure 111, the piezoelectric stack structure 100 further includes: a dummy electrode 112, located on either side of the piezoelectric layer 102 or on both sides of the piezoelectric layer 102, wherein the dummy electrode 112 and the first electrode 101 or the second electrode 103 located on the same side of the piezoelectric layer 102 are made of the same material and are disposed in the same layer, and the dummy electrode 112 and the first electrode 101 or the second electrode 103 on the same side are spaced apart.

[0045] It should be noted that since the material of the dummy electrode 112 is the same as that of the first electrode 101 or the second electrode 103, that is, the material of the dummy electrode 112 is a conductive material, the thermal conductivity of the dummy electrode 112 is better than that of the piezoelectric layer 102. When the second heat dissipation structure 111 is subsequently formed through the dummy electrode 112 and the piezoelectric layer 102, it can further promote the rapid transfer of heat generated by the vibration of the piezoelectric layer 102 of the resonant unit i' to the second heat dissipation structure 111 through the dummy electrode 112, which is beneficial to further increase the heat dissipation efficiency.

[0046] It should also be noted that the dummy electrode 112 is spaced apart from the first electrode 101 or the second electrode 103 on the same side. When a second heat dissipation structure 111 is formed that penetrates the dummy electrode 112 and the piezoelectric layer 102, it is beneficial to reduce the risk of short circuit between the first electrode 101 or the second electrode 103 on the same side as the dummy electrode 112 and the second electrode 103 or the first electrode 101 on the other side due to the second heat dissipation structure 111.

[0047] Specifically, the dummy electrode 112 is located on the first side 104 of the piezoelectric layer 102; or, the dummy electrode 112 is located on the second side 105 of the piezoelectric layer 102; or, the dummy electrode 112 is located on both sides of the piezoelectric layer 102.

[0048] As an example, the dummy electrode 112 is located on the first side 104 of the piezoelectric layer 102.

[0049] In some embodiments, the second heat dissipation structure 111 extends sequentially through the dummy electrode 112 and the piezoelectric layer 102 from the side where the dummy electrode 112 is located, and is in contact with the dummy electrode 112. Accordingly, the dummy electrode 112 is connected to the first electrode 101 or the second electrode 103 on the other side through the second heat dissipation structure 111, so that the dummy electrode 112 and the first electrode 101 or the second electrode 103 on the other side are at the same potential. Therefore, no electric field is generated between the dummy electrode 112 and the first electrode 101 or the second electrode 103 on the other side, thereby reducing the probability of parasitic resonance between the dummy electrode 112 and the first electrode 101 or the second electrode 103 on the other side.

[0050] In some embodiments, when the heat dissipation structure 107 includes a second heat dissipation structure 111, and the second heat dissipation structure 111 sequentially penetrates the dummy electrode 112 and the piezoelectric layer 102, the material of the second heat dissipation structure 111 includes a metallic material.

[0051] It should be noted that metallic materials have good electrical conductivity. Therefore, when the second heat dissipation structure 111 passes through the dummy electrode 112 and the piezoelectric layer 102 sequentially from the side where the dummy electrode 112 is located, the dummy electrode 112 can be electrically connected to the first electrode 101 or the second electrode 103 on the other side through the second heat dissipation structure 111, thereby making the dummy electrode 112 and the first electrode 101 or the second electrode 103 on the other side at the same potential.

[0052] In other embodiments, dummy electrodes may be omitted, depending on actual needs.

[0053] It should be noted that, when the heat dissipation structure includes a second heat dissipation structure, and the second heat dissipation structure only penetrates the piezoelectric layer, the material of the heat dissipation structure includes one or more of the following: metallic materials, silicon carbide, diamond, and graphene.

[0054] In some embodiments, when the material of the heat dissipation structure 107 is a metal material, the heat dissipation structure 107 includes a heat dissipation main structure 108 and an adhesion seed layer 109 located between the heat dissipation main structure 108 and the piezoelectric stack structure 100, wherein the adhesion seed layer 109 is in contact with the first electrode 101 or the second electrode 103.

[0055] The adhesion seed layer 109 is used to enhance the adhesion between the heat dissipation body structure 108 and the piezoelectric stack structure 100. At the same time, the adhesion seed layer 109 is also used to provide a growth basis for the formation of the heat dissipation body structure 108 and to provide a uniform starting surface.

[0056] Therefore, in some embodiments, the adhesion seed layer 109 adopts a stacked structure of titanium and copper.

[0057] In some embodiments, the filter further includes: a first support layer 113 located on the surface of the second electrode 103 facing away from the piezoelectric layer 102, and located at the edge of the piezoelectric stack structure 100 and the junction of the adjacent resonant unit i', the first support layer 113 and the piezoelectric stack structure 100 forming a first cavity 114; and a first substrate 115 located on the side of the first support layer 113 away from the piezoelectric layer 102, the first substrate 115 sealing the first cavity 114.

[0058] The first support layer 113 is used to prepare for bonding the first substrate 115.

[0059] Specifically, the material of the first support layer 113 includes one or a combination of tetraethyl orthosilicate (TEOS), silicon oxide, silicon nitride, aluminum oxide, and aluminum nitride. In some embodiments, the material of the first support layer 113 is silicon oxide.

[0060] The first substrate 115 can be any suitable substrate known to those skilled in the art, such as at least one of the following materials: silicon, germanium, silicon germanium, silicon carbide, silicon germanium carbide, indium arsenide, gallium arsenide, indium phosphide, or other III / V compound semiconductors, including multilayer structures composed of these semiconductors, or silicon on insulator, silicon on insulator, silicon on insulator, silicon on insulator with a germanium layer, silicon with a trap-rich layer, and germanium on insulator, or it can be a double-side polished wafer (DSP), or a ceramic substrate such as alumina, a quartz or glass substrate, etc.

[0061] The first cavity 114 helps reduce the vibration energy loss of the filter and improves the acoustic-electric conversion performance of the filter.

[0062] In some embodiments, the surface of the second electrode 103 located at the edge of the first cavity 114 has a protrusion structure 116 for lateral reflection of sound waves, which helps to increase the residence time of sound waves in the first cavity 114 and thereby reduce energy dissipation.

[0063] In some embodiments, the protrusion structure 116 is made of the same material as the second electrode 103. In other embodiments, the material of the protrusion structure may be different from the material of the second electrode.

[0064] As an example, when the protrusion structure 116 and the second electrode 103 are made of the same material, the protrusion structure 116 and the second electrode 103 can be formed by etching the same material, and the corresponding protrusion structure 116 and the second electrode 103 are an integral structure.

[0065] In other embodiments, the protrusion structure and the second electrode may not be an integral structure, depending on actual needs.

[0066] In some embodiments, the filter further includes a protective layer 117 located between the first substrate 115 and the first support layer 113, on the sidewall of the first support layer 113 facing the first cavity 114, and on the second electrode 103 and the piezoelectric layer 102 between adjacent first support layers 113, and the protective layer 117 is also located on the protrusion structure 116.

[0067] The protective layer 117 is used to provide a good bonding surface for the bonding between the first substrate 115 and the first support layer 113. At the same time, the protective layer 117 is also used to block the second electrode 103 between adjacent first support layers 113 from external moisture, so that the surface of the second electrode 103 is not easily oxidized.

[0068] The protective layer 117 is made of one or more of silicon oxide, silicon nitride, and silicon oxynitride. As an example, the protective layer 117 is made of silicon oxide.

[0069] In some embodiments, the filter further includes a first passivation layer 128 covering the surface of the heat dissipation structure 107 and the electrode layer surface of the piezoelectric layer 102 on the side opposite to the first substrate 115.

[0070] The first passivation layer 128 is used to protect the heat dissipation structure 107 and the electrode layer, which helps to prevent the heat dissipation structure 107 and the electrode layer from being exposed to the air, thereby reducing the probability of moisture and pollutants in the air adhering to the heat dissipation structure 107 and the electrode layer.

[0071] In some embodiments, the material of the first passivation layer 128 is silicon oxide.

[0072] In some embodiments, the filter further includes a heat dissipation electrode 118 located at the junction of adjacent resonant units i', the heat dissipation electrode 118 penetrating the first substrate 115 and the first support layer 113.

[0073] It should be noted that the heat generated by the vibration of the piezoelectric layer 102 in the resonant unit i' can be transferred to the heat dissipation electrode 118 through the second electrode 103 and the heat dissipation structure 107. Then, the heat dissipation electrode 118 transfers the heat to the external environment, further enhancing the heat conduction effect of the resonant unit i' located away from the edge of the piezoelectric stack structure 100.

[0074] Specifically, the heat dissipation electrode 118 is in contact with the second electrode 103.

[0075] It should be noted that the heat dissipation electrode 118 is in contact with the second electrode 103, and the second electrode 103 is in contact with the heat dissipation structure 107. Therefore, the heat generated by the vibration of the piezoelectric layer 102 in the resonant unit i' can be quickly transferred to the heat dissipation electrode 118 through the second electrode 103 and the heat dissipation structure 107.

[0076] In other embodiments, the heat dissipation electrode may not be in contact with the second electrode.

[0077] In some embodiments, the heat dissipation electrode 118 includes: a heat dissipation electrode body 119 located at the junction of adjacent resonant units i', the heat dissipation electrode body 119 penetrating the first substrate 115 and the first support layer 113; a first seed layer 120 covering the bottom and sidewalls of the heat dissipation electrode body 119, the first seed layer 120 being in contact with the second electrode 103; a first solder ball 121 located on the surface of the first substrate 115 facing away from the piezoelectric layer 102, in contact with the heat dissipation electrode body 119; and a second seed layer 122 located between the heat dissipation electrode body 119 and the first solder ball 121.

[0078] The heat dissipation electrode body 119 serves as the main part of the heat dissipation electrode 118 and is used to transfer the heat generated by the vibration of the piezoelectric layer 102 of the resonant unit i' to the external environment through the first solder ball 121.

[0079] In some embodiments, the heat dissipation electrode body 119 is made of a metallic material. The metallic material has good thermal conductivity, allowing the heat generated by the vibration of the piezoelectric layer 102 in the resonant unit i' to be quickly transferred to the heat dissipation electrode body 119 via the second electrode 103 and the heat dissipation structure 107. The heat dissipation electrode body 119 then transfers the heat to the external environment via the first solder ball 121.

[0080] The first seed layer 120 is used to enhance the adhesion between the heat dissipation electrode body 119 and the first substrate 115, between the heat dissipation electrode body 119 and the first support layer 113, and between the heat dissipation electrode body 119 and the second electrode 103. At the same time, the first seed layer 120 is also used to provide a growth basis for the formation of the heat dissipation electrode body 119 and to provide a uniform starting surface.

[0081] Therefore, in some embodiments, the first seed layer 120 adopts a stacked structure of titanium and copper.

[0082] The second seed layer 122 is used to enhance the adhesion between the first solder ball 121 and the heat dissipation electrode body 119. At the same time, the second seed layer 122 is also used to provide a growth basis for the formation of the first solder ball 121 and to provide a uniform starting surface.

[0083] The second seed layer 122 also adopts a stacked structure of titanium and copper.

[0084] The first solder ball 121 serves as the connection point between the heat dissipation electrode 118 and the package structure, and is responsible for conducting heat to the external environment.

[0085] In some embodiments, along the thickness direction of the piezoelectric stack structure 100, the position of the heat dissipation electrode 118 corresponds one-to-one with the position of the heat dissipation structure 107.

[0086] It should be noted that since the position of the heat dissipation electrode 118 corresponds one-to-one with the position of the heat dissipation structure 107, the heat generated by the vibration of the piezoelectric layer 102 in the resonant unit i' can be directly conducted from the heat dissipation structure 107 to the heat dissipation electrode 118 without going through an extra heat conduction path, thereby improving the heat dissipation efficiency.

[0087] In other embodiments, depending on actual needs, the position of the heat dissipation electrode and the position of the heat dissipation structure may not correspond one-to-one along the thickness direction of the piezoelectric stack structure.

[0088] In some embodiments, the filter further includes a signal electrode 127 located at the edge of the piezoelectric stack structure 100 and penetrating the first support layer 113 and the first substrate 115.

[0089] During the operation of the filter, the signal electrode 127 is used as the input or output of the signal.

[0090] The signal electrode 127 includes: a signal electrode body 135 located at the edge of the piezoelectric stack structure 100, the signal electrode body 135 penetrating the first substrate 115 and the first support layer 113; a third seed layer 129 covering the bottom and sidewalls of the signal electrode body 135, the third seed layer 129 being in contact with the second electrode 103; a second solder ball 130 located on the surface of the first substrate 115 facing away from the piezoelectric layer 102, in contact with the signal electrode body 135; and a fourth seed layer 131 located between the signal electrode body 135 and the second solder ball 130.

[0091] Specifically, the signal electrode 127 and the heat dissipation electrode 118 are formed in the same step, which helps to simplify the process complexity and improve work efficiency.

[0092] In some embodiments, the filter further includes: an interconnect structure 132 located at the edge of the piezoelectric stack structure 100, the interconnect structure 132 being located on the same side of the piezoelectric stack structure 100 as the heat dissipation structure 107, and the position of the interconnect structure 132 corresponding to the position of the signal electrode 127, the interconnect structure 132 being in contact with either or both of the first electrode 101 and the second electrode 103.

[0093] The interconnect structure 132 is used to electrically connect to the signal electrode 127, and the signal electrode 127 applies an electrical signal to the piezoelectric stack structure 100 through the interconnect structure 132.

[0094] Specifically, the interconnect structure 132 includes: a first interconnect structure 133 that penetrates the piezoelectric layer 102 and is connected to the second electrode 103; and a second interconnect structure 134 that penetrates the piezoelectric layer 102, one end of the second interconnect structure 134 being connected to the second electrode 103 and the other end of the second interconnect structure 134 being connected to the first electrode 101.

[0095] It should be noted that the second interconnect structure 134 located at the edge of the piezoelectric stack structure 100 short-circuits the first electrode 101 and the second electrode 103 located on both sides of the piezoelectric layer 102. This is beneficial to ensure that the first electrode 101 and the second electrode 103 located at the edge of the piezoelectric stack structure 100 are at the same potential. Therefore, no electric field is generated between the first electrode 101 and the second electrode 103 located at the edge of the piezoelectric stack structure 100, thereby reducing the probability of parasitic resonance between the first electrode 101 and the second electrode 103 located at the edge of the piezoelectric stack structure 100.

[0096] In some embodiments, when the interconnect structure 132 includes a second interconnect structure 134, the second electrode 103 located at the edge of the piezoelectric stack structure 100 is spaced apart from the second electrode 103 located away from the edge of the piezoelectric stack structure 100, or the first electrode 101 located at the edge of the piezoelectric stack structure 100 is spaced apart from the first electrode 101 located away from the edge of the piezoelectric stack structure 100. When forming the second interconnect structure 134 that penetrates the piezoelectric layer 102, it is beneficial to reduce the risk of short circuits between the first electrode 101 and the second electrode 103 located on both sides of the piezoelectric layer 102 due to the second interconnect structure 134.

[0097] In some embodiments, the filter further includes a second passivation layer 126 covering the surface of the heat dissipation electrode body 119 and the surface of the first substrate 115 on the side away from the piezoelectric layer 102, wherein the second passivation layer 126 exposes a portion of the width of the heat dissipation electrode body 119.

[0098] The second passivation layer 126 is used to protect the heat dissipation electrode body 119, which helps to prevent the heat dissipation electrode body 119 from being exposed to the air, thereby reducing the probability of moisture and pollutants in the air adhering to the heat dissipation electrode body 119.

[0099] It should be noted that the second passivation layer 126 also covers the surface of the signal electrode body 135 and the surface of the first substrate 115 on the side away from the piezoelectric layer 102, and the second passivation layer 126 exposes a portion of the width of the signal electrode body 135.

[0100] In some embodiments, the material of the second passivation layer 126 is photoresist.

[0101] It should be noted that since the heat dissipation electrode body 119 is made of metal, and the second passivation layer 126 needs to expose a portion of the width of the heat dissipation electrode body 119, using photoresist as the second passivation layer 126 can expose the heat dissipation electrode body 119 through exposure and development, without the need for etching, which helps to reduce the probability of metal contamination of the etching equipment.

[0102] In some embodiments, the filter further includes a second support layer 123 located on the first side 104 of the piezoelectric layer 102 and at the edge of the piezoelectric stack structure 100, wherein the second support layer 123 and the piezoelectric stack structure 100 form a second cavity 124.

[0103] The second support layer 123 is used to bond the second substrate 125.

[0104] The second cavity 124 helps reduce the vibration energy loss of the filter and improves the acoustic-electric conversion performance of the filter.

[0105] The material of the second support layer 123 can be an organic material or a metal material with strong adhesion.

[0106] Specifically, if the material of the second support layer 123 is a metal material, the metal material includes gold or copper-tin. Accordingly, the second support layer 123 can be bonded to the first side 104 of the piezoelectric layer 102 by gold-gold bonding or copper-tin bonding.

[0107] In some embodiments, the material of the second support layer 123 is a dry film. In other embodiments, the material of the second support layer may also be other photosensitive materials.

[0108] In some embodiments, the second support layer 123 is also located at the junction of the adjacent resonant unit i' corresponding to the heat dissipation electrode 118, and the second support layer 123 is connected to one or both of the first heat dissipation structure 110 and the second heat dissipation structure 111, and the second support layer 123 and the piezoelectric stack structure 100 form a second cavity 124.

[0109] It should be noted that the second support layer 123 located at the junction of the adjacent resonant unit i' corresponding to the heat dissipation electrode 118 can further enhance the support effect at the position of the adjacent resonant unit i', thereby improving the structural stability of the filter.

[0110] As an example, the second support layer 123 is located at the edge of the piezoelectric stack structure 100 and at the junction of the adjacent resonant unit i' corresponding to the second heat dissipation structure 111.

[0111] In other embodiments, depending on actual needs, the second support layer is located only at the edge of the piezoelectric stacked structure; or, the second support layer is located at the edge of the piezoelectric stacked structure and at the junction of the adjacent resonant units corresponding to the first heat dissipation structure; or, the second support layer is located at the edge of the piezoelectric stacked structure and at the junction of the adjacent resonant units corresponding to the first heat dissipation structure and the second heat dissipation structure, respectively.

[0112] In some embodiments, the filter further includes a second substrate 125 located on the side of the second support layer 123 away from the piezoelectric layer 102, the second substrate 125 sealing the second cavity 124.

[0113] The second substrate 125 can be any suitable substrate known to those skilled in the art, such as at least one of the following materials: silicon, germanium, silicon germanium, silicon carbide, silicon carbide, indium arsenide, gallium arsenide, indium phosphide, or other III / V compound semiconductors, including multilayer structures composed of these semiconductors, or silicon on insulator, silicon on insulator, silicon on insulator, silicon on insulator with germanium, silicon with trap-rich layers, and germanium on insulator, or it can be a double-sided polished silicon wafer, or a ceramic substrate such as alumina, quartz, or glass substrate.

[0114] Accordingly, this disclosure also provides a method for forming a filter. Figures 3 to 14 This is a schematic diagram of the structure corresponding to each step in one embodiment of the filter formation method disclosed herein.

[0115] refer to Figure 3 A piezoelectric stack structure 500 is provided, the piezoelectric stack structure 500 includes a first electrode 501, a piezoelectric layer 502 and a second electrode 503 stacked together. The piezoelectric layer 502 includes a first side 504 and a second side 505 disposed opposite to each other. The first electrode 501 is located on the first side 504 and the second electrode 503 is located on the second side 505. Along a plane direction perpendicular to the thickness direction of the piezoelectric stack structure 500, the piezoelectric stack structure 500 includes a plurality of resonant units I.

[0116] The piezoelectric stack structure 500 is used to prepare for the subsequent formation of a filter. The corresponding piezoelectric stack structure 500 is used to realize the mutual conversion between electrical signals and acoustic signals, so that the filter can filter the signals.

[0117] The first electrode 501 and the second electrode 503 are both made of conductive materials. These conductive materials can be metallic materials with conductive properties, such as one or more of molybdenum, aluminum, copper, platinum, gold, iridium, osmium, rhenium, palladium, rhodium, ruthenium, and tungsten.

[0118] It is understood that in other embodiments, the materials of the first electrode and the second electrode may also be other electrode materials suitable for forming a piezoelectric stack structure.

[0119] The piezoelectric layer 502 can be made of piezoelectric crystal, piezoelectric ceramic, or piezoelectric polymer. Specifically, the piezoelectric crystal can be aluminum nitride, lead zirconate titanate, quartz crystal, lithium gallium oxide, lithium germanate, titanium germanate, lithium niobate, or lithium tantalate, etc., and the piezoelectric polymer can be polyvinylidene fluoride, vinylidene fluoride-trifluoroethylene copolymer, nylon-11, or vinylidene dicyanide-vinyl acetate alternating copolymer, etc. In some embodiments, the piezoelectric layer 502 is made of aluminum nitride.

[0120] The first side 504 is used to provide a process platform for forming the first electrode 501; the second side 505 is used to provide a process platform for forming the second electrode 503.

[0121] It should be noted that the first electrode 501 is located on the first side 504, and the second electrode 503 is located on the second side 505. When an electrical signal from an external circuit is applied to the second electrode 503 at the edge of the piezoelectric stack structure 500, an electric field is generated between the first electrode 501 and the second electrode 503 at the edge of the piezoelectric stack structure 500. This electric field acts on the piezoelectric layer 502, causing the piezoelectric layer 502 to produce a piezoelectric effect. Consequently, the piezoelectric layer 502 generates mechanical vibration and generates an electrical signal in the opposite direction. Since the first electrode 501 or the second electrode 503 at the junction of adjacent resonant units I is connected to the first electrode 501 or the second electrode 503 at the edge, the electrical signal generated by the piezoelectric layer 502 can be transmitted through the first electrode 501 or the second electrode 503 at the edge to the first electrode 501 or the second electrode 503 at the junction of adjacent resonant units I, thereby realizing the cross-unit transmission of the electrical signal.

[0122] Specifically, the method for forming the filter includes: providing a temporary substrate 506 (such as...) Figure 3 (as shown); the steps of providing the piezoelectric stacked structure 500 include: forming a first electrode 501 on a temporary substrate 506; forming a piezoelectric layer 502 on the first electrode 501; and forming a second electrode 503 on the piezoelectric layer 502.

[0123] In some embodiments, the temporary substrate 506 may be any suitable substrate known to those skilled in the art, such as at least one of the following materials: silicon, germanium, silicon germanium, silicon carbide, silicon carbide, indium arsenide, gallium arsenide, indium phosphide, or other III / V compound semiconductors, including multilayer structures composed of these semiconductors, or silicon on insulator, silicon on insulator, silicon on insulator, silicon on insulator with germanium, silicon with trap-rich layers, and germanium on insulator, or it may be a double-sided polished silicon wafer, or a ceramic substrate such as alumina, a quartz or glass substrate, etc.

[0124] In some embodiments, after providing the temporary substrate 506 and before providing the piezoelectric stack structure 500, the method further includes forming a stop layer 507 on the temporary substrate 506.

[0125] It should be noted that, since the temporary substrate 506 needs to be removed later, the stop layer 507 is used as a stop position in the step of removing the temporary substrate 506, which reduces the difficulty of removing the temporary substrate 506 and helps to prevent the subsequent process of removing the temporary substrate 506 from affecting the first electrode 501.

[0126] The stop layer 507 is made of one or more of silicon oxide, silicon nitride, and silicon oxynitride. In some embodiments, the stop layer 507 is made of silicon oxide. In some embodiments, the stop layer 507 is formed using a deposition process. Specifically, the deposition process may be chemical vapor deposition or atomic layer deposition, etc.

[0127] refer to Figure 4 After providing the piezoelectric stack structure 500, before forming the first support layer on the surface of the second electrode 503 facing away from the piezoelectric layer 502, the method further includes: patterning the second electrode 503 such that the second electrode 503 located at the edge position of the piezoelectric stack structure 500 is spaced apart from the second electrode 503 located away from the edge position of the piezoelectric stack structure 500.

[0128] It should be noted that the second electrode 503 located at the edge of the piezoelectric stack structure 500 is spaced apart from the second electrode 503 located away from the edge of the piezoelectric stack structure 500. When an interconnect structure is subsequently formed at the edge of the piezoelectric stack structure 500, this helps to reduce the risk of short circuits between the first electrode 501 and the second electrode 503 located on both sides of the piezoelectric layer 502 due to the interconnect structure.

[0129] It should also be noted that, compared with the scheme of forming the first support layer on the surface of the second electrode 503 facing away from the piezoelectric layer 502, the scheme of patterning the second electrode 503 before forming the first support layer on the surface of the second electrode 503 facing away from the piezoelectric layer 502 avoids the problem of needing to perform regional patterning processing of the second electrode 503 due to the coverage of the first support layer, thereby reducing the number of steps in patterning the second electrode 503 and reducing the complexity of the process.

[0130] Continue to refer to Figure 4 The step of patterning the second electrode 503 further includes forming a protrusion structure 508 on the surface of the second electrode 503 at the edge of the first cavity to be formed.

[0131] The protruding structure 508 is used to reflect sound waves laterally, which helps to increase the residence time of sound waves in the first cavity and thus reduce energy dissipation.

[0132] In some embodiments, the protrusion structure 508 is made of the same material as the second electrode 503. In other embodiments, the material of the protrusion structure may be different from the material of the second electrode.

[0133] As an example, when the protrusion structure 508 and the second electrode 503 are made of the same material, the protrusion structure 508 and the second electrode 503 can be formed by etching the same material, and the corresponding protrusion structure 508 and the second electrode 503 are an integral structure.

[0134] In other embodiments, the protrusion structure and the second electrode may not be an integral structure, depending on actual needs.

[0135] refer to Figure 5 After providing the piezoelectric stacked structure 500, and before forming a heat dissipation structure on the first side of the piezoelectric layer 502, the method further includes: forming a first support layer 509 on the surface of the second electrode 503 facing away from the piezoelectric layer 502, the first support layer 509 being located at the edge of the piezoelectric stacked structure 500 and at the junction of the adjacent resonant unit I, the first support layer 509 and the piezoelectric stacked structure 500 forming a first cavity 510.

[0136] The first support layer 509 is used to prepare for bonding the first substrate.

[0137] Specifically, the material of the first support layer 509 includes one or more combinations of tetraethyl orthosilicate, silicon oxide, silicon nitride, aluminum oxide, and aluminum nitride. In some embodiments, the material of the first support layer 509 is silicon oxide.

[0138] The first cavity 510 helps reduce the vibration energy loss of the filter and improves the acoustic-electric conversion performance of the filter.

[0139] refer to Figure 6 A protective layer 513 is formed on the top of the first support layer 509, on the side wall of the first support layer 509 facing the first cavity 510, and on the second electrode 503 and piezoelectric layer 502 between adjacent first support layers 509. The protective layer 513 also covers the protruding structure 508.

[0140] The protective layer 513 is used to provide a good bonding surface for subsequent bonding between the first substrate and the first support layer 509. At the same time, the protective layer 513 is also used to isolate the second electrode 503 between adjacent first support layers 509 from external moisture, so that the surface of the second electrode 503 is not easily oxidized.

[0141] The protective layer 513 is made of one or more of silicon oxide, silicon nitride, and silicon oxynitride. As an example, the protective layer 513 is made of silicon oxide.

[0142] Continue to refer to Figure 6 After forming the first support layer 509 on the surface of the second electrode 503 facing away from the piezoelectric layer 502, a first substrate 511 is bonded to the side of the first support layer 509 away from the piezoelectric layer 502, and the first substrate 511 seals the first cavity 510.

[0143] The first substrate 511 can be any suitable substrate known to those skilled in the art, such as at least one of the following materials: silicon, germanium, silicon germanium, silicon carbide, silicon carbide, indium arsenide, gallium arsenide, indium phosphide, or other III / V compound semiconductors, including multilayer structures composed of these semiconductors, or silicon on insulator, silicon on insulator, silicon on insulator, silicon on insulator with germanium, silicon with trap-rich layers, and germanium on insulator, or it can be a double-sided polished silicon wafer, or a ceramic substrate such as alumina, a quartz or glass substrate, etc.

[0144] refer to Figure 7 After the first substrate 511 is bonded to the side of the first support layer 509 away from the piezoelectric layer 502, the method further includes: removing the temporary substrate 506 and the stop layer 507.

[0145] Specifically, a portion of the temporary substrate 506 is removed by a grinding process, and then the remaining thickness of the temporary substrate 506 is removed by a wet etching process or a dry etching process.

[0146] It should be noted that the grinding process can quickly remove most of the thickness of the temporary substrate 506, thereby reducing the thickness of the remaining temporary substrate 506. This shortens the time required for wet etching or dry etching processes to remove the remaining thickness of the temporary substrate 506 and improves process efficiency.

[0147] It should also be noted that wet etching or dry etching processes have the characteristic of high etching selectivity, which enables precise etching stop on the stop layer 507.

[0148] In some embodiments, the stop layer 507 is removed using a dry etching process or a wet etching process.

[0149] refer to Figure 8 After providing the piezoelectric stacked structure 500, before forming the second heat dissipation structure at the junction of adjacent resonant units I, the method further includes: forming a dummy electrode 512 on either side of the piezoelectric layer 502 or on both sides of the piezoelectric layer 502 respectively. The dummy electrode 512 and the first electrode 501 or the second electrode 503 located on the same side of the piezoelectric layer 502 are made of the same material and are in the same layer. The dummy electrode 512 and the first electrode 501 or the second electrode 503 on the same side are spaced apart.

[0150] It should be noted that since the material of the dummy electrode 512 is the same as that of the first electrode 501 or the second electrode 503, that is, the dummy electrode 512 is a conductive material, the thermal conductivity of the dummy electrode 512 is better than that of the piezoelectric layer 502. When a second heat dissipation structure is subsequently formed that penetrates the dummy electrode 512 and the piezoelectric layer 502, the heat generated by the vibration of the piezoelectric layer 502 in the resonant unit I can be quickly transferred to the second heat dissipation structure through the dummy electrode 512, which is beneficial to further increase the heat dissipation efficiency.

[0151] It should also be noted that the dummy electrode 512 is spaced apart from the first electrode 501 or the second electrode 503 on the same side. When a second heat dissipation structure is subsequently formed that penetrates the dummy electrode 512 and the piezoelectric layer 502, it helps to reduce the risk of short circuit between the first electrode 501 or the second electrode 503 on the same side as the dummy electrode 512 and the first electrode 501 or the second electrode 503 on the other side due to the second heat dissipation structure.

[0152] Specifically, the dummy electrode 512 is located on the first side 504 of the piezoelectric layer 502; or, the dummy electrode 512 is located on the second side 505 of the piezoelectric layer 502; or, the dummy electrode 512 is located on both sides of the piezoelectric layer 502.

[0153] As an example, the dummy electrode 512 is located on the first side 504 of the piezoelectric layer 502.

[0154] In some embodiments, when the heat dissipation structure includes a second heat dissipation structure, and the second heat dissipation structure sequentially penetrates the dummy electrode 512 and the piezoelectric layer 502, the material of the heat dissipation structure includes a metallic material.

[0155] It should be noted that metallic materials have good electrical conductivity. Therefore, when the second heat dissipation structure passes through the dummy electrode 512 and the piezoelectric layer 502 sequentially from the side where the dummy electrode 512 is located, the dummy electrode 512 can be electrically connected to the first electrode 501 or the second electrode 503 on the other side through the second heat dissipation structure, thereby making the dummy electrode 512 and the first electrode 501 or the second electrode 503 on the other side at the same potential.

[0156] In other embodiments, dummy electrodes may be omitted depending on actual needs. It should be noted that, in the step of forming the heat dissipation structure at the junction of adjacent resonant units, if the heat dissipation structure includes a second heat dissipation structure that only penetrates the piezoelectric layer, the material of the heat dissipation structure includes one or more of metallic materials, silicon carbide, diamond, and graphene.

[0157] Continue to refer to Figure 8The step of forming a dummy electrode 512 on either side of the piezoelectric layer 502 or on both sides of the piezoelectric layer 502 further includes removing the first electrode 501 at the edge position of the piezoelectric stack structure 500.

[0158] It should be noted that removing the first electrode 501 at the edge of the piezoelectric stack structure 500 and forming an interconnect structure at the edge of the subsequent piezoelectric stack structure 500 helps to reduce the risk of short circuits caused by the interconnect structure with the first electrode 501 or the second electrode 503 located on both sides of the piezoelectric layer 502.

[0159] refer to Figures 9 to 10 A heat dissipation structure 514 is formed at the junction of adjacent resonant units I. The heat dissipation structure 514 is in contact with either the first electrode 501 or the second electrode 503, or the heat dissipation structure 514 is in contact with both the first electrode 501 and the second electrode 503.

[0160] The heat dissipation structure 514 is used to facilitate the rapid transverse conduction of heat generated by the vibration of the piezoelectric layer 502 in the resonant unit I along the extension direction of the piezoelectric layer 502.

[0161] It should be noted that by setting a heat dissipation structure 514 at the junction of adjacent resonant units I, the heat generated by the vibration of the piezoelectric layer 502 in the resonant unit I can be effectively promoted to be quickly conducted laterally along the extension direction of the piezoelectric layer 502. This enhances the heat conduction effect of the heat conduction path of the resonant unit I at a position far from the edge of the piezoelectric stack structure 500, thereby improving the heat dissipation efficiency of the filter and thus improving the performance and reliability of the filter.

[0162] In the step of forming the heat dissipation structure 514 at the junction of adjacent resonant units I, the heat dissipation structure 514 includes one or both of the first heat dissipation structure 517 and the second heat dissipation structure 518.

[0163] In some embodiments, in the step of forming the heat dissipation structure 514 at the junction of adjacent resonant units I, if the heat dissipation structure 514 includes a first heat dissipation structure 517, the material of the first heat dissipation structure 517 includes one or more of metallic materials, silicon carbide, diamond, and graphene.

[0164] It should be noted that metallic materials, silicon carbide, diamond, and graphene all have good thermal conductivity, which can quickly conduct the heat generated by the vibration of the piezoelectric layer 502 in the resonant unit I laterally along the extension direction of the piezoelectric layer 502.

[0165] As an example, in the case where the heat dissipation structure 514 includes a first heat dissipation structure 517, and the material of the first heat dissipation structure 517 is a metal material.

[0166] Specifically, the metallic material includes one or more of aluminum, titanium copper, molybdenum, tungsten, and gold. Aluminum, titanium copper, molybdenum, tungsten, and gold all have high thermal conductivity, thus enabling them to rapidly conduct the heat generated by the vibration of the piezoelectric layer 502 in the resonant unit I laterally along the extension direction of the piezoelectric layer 502.

[0167] It should be noted that the heat dissipation structure 514 may include only the first heat dissipation structure 517, or the heat dissipation structure 514 may include only the second heat dissipation structure 518, or the heat dissipation structure 514 may include both the first heat dissipation structure 517 and the second heat dissipation structure 518.

[0168] In some embodiments, the step of forming the first heat dissipation structure 517 includes: forming the first heat dissipation structure 517 on the first electrode 501 or the second electrode 503 on either side of the piezoelectric layer 502, and the first heat dissipation structure 517 is in contact with the first electrode 501 or the second electrode 503 located on the same side of the piezoelectric layer 502.

[0169] The first heat dissipation structure 517 is located on the first electrode 501 or the second electrode 503 on either side of the piezoelectric layer 502. On the one hand, it conducts the heat generated by the piezoelectric layer 502 during operation from the first electrode 501 or the second electrode 503 to the first heat dissipation structure 517, thereby achieving the heat dissipation function. On the other hand, the first heat dissipation structure 517 is located on the first electrode 501 or the second electrode 503, which helps to increase the thickness of the electrode layer at the junction of adjacent resonant units I, thereby reducing the resistance value at the junction of adjacent resonant units I.

[0170] Specifically, when the heat dissipation structure 514 includes only the first heat dissipation structure 517, the first heat dissipation structure 517 is located on the first electrode 501 on the first side 504 of the piezoelectric layer 502; or, the first heat dissipation structure 517 is located on the second electrode 503 on the second side 505 of the piezoelectric layer 502; or, the first heat dissipation structure 517 is located on the first electrode 501 and the second electrode 503 on both sides of the piezoelectric layer 502.

[0171] In some embodiments, the step of forming the second heat dissipation structure 518 includes: referencing Figure 9 An opening 519 is formed from either side of the piezoelectric layer 502, penetrating the piezoelectric layer 502, and the opening 519 exposes the surface of the second electrode 503 or the first electrode 501 on the other side of the piezoelectric layer 502 facing the piezoelectric layer 502; Reference Figure 10A second heat dissipation structure 518 is formed in the opening 519, and the second heat dissipation structure 518 is in contact with the second electrode 503 or the first electrode 501 exposed by the opening 519.

[0172] The second heat dissipation structure 518 penetrates the piezoelectric layer 502 from either side and contacts the surface of the second electrode 503 or the first electrode 501 on the other side of the piezoelectric layer 502 facing the piezoelectric layer 502. This enables rapid heat conduction between the two sides of the piezoelectric layer 502 and prevents heat from accumulating inside the piezoelectric layer 502.

[0173] When the heat dissipation structure 514 includes only the second heat dissipation structure 518, the second heat dissipation structure 518 extends through the piezoelectric layer 502 from the first side 504 and contacts the second electrode 503 of the second side 505 of the piezoelectric layer 502 facing the surface of the piezoelectric layer 502; or, the second heat dissipation structure 518 extends through the piezoelectric layer 502 from the second side 505 and contacts the first electrode 501 of the first side 504 of the piezoelectric layer 502 facing the surface of the piezoelectric layer 502; or, the second heat dissipation structure 518 extends through the piezoelectric layer 502 from both sides and contacts the second electrode 503 and the first electrode 501 of the piezoelectric layer 502 facing the surface of the piezoelectric layer 502, respectively.

[0174] As an example, when the heat dissipation structure 514 includes the first heat dissipation structure 517 and the second heat dissipation structure 518, in the step of forming the second heat dissipation structure 518 in the opening 519, the first heat dissipation structure 517 is simultaneously formed on the first electrode 501 or the second electrode 503 on the same side of the piezoelectric layer 502.

[0175] It should be noted that when the heat dissipation structure 514 includes the first heat dissipation structure 517 and the second heat dissipation structure 518, forming the second heat dissipation structure 518 and the first heat dissipation structure 517 in the same step is beneficial to reduce the complexity of the process and improve production efficiency.

[0176] Specifically, when the heat dissipation structure 514 includes a first heat dissipation structure 517 and a second heat dissipation structure 518, the first heat dissipation structure 517 is located on the first electrode 501 of the first side 504 of the piezoelectric layer 502, and the second heat dissipation structure 518 extends from the first side 504 of the piezoelectric layer 502 through the piezoelectric layer 502 and contacts the second electrode 503 of the second side 505 of the piezoelectric layer 502 facing the surface of the piezoelectric layer 502; or, the first heat dissipation structure 517 is located on the first electrode 501 of the first side 504 of the piezoelectric layer 502, and the second heat dissipation structure 518 extends from the second side 504 of the piezoelectric layer 502 through the first electrode 501 of the first side 504 of the piezoelectric layer 502. Side 505 penetrates the piezoelectric layer 502 and contacts the surface of the first electrode 501 of the first side 504 of the piezoelectric layer 502 facing the piezoelectric layer 502; or, a first heat dissipation structure 517 is located on the first electrode 501 of the first side 504 of the piezoelectric layer 502, and a second heat dissipation structure 518 penetrates the piezoelectric layer 502 from both sides and contacts the surfaces of the second electrode 503 and the first electrode 501 of the piezoelectric layer 502 facing the piezoelectric layer 502, respectively; or, a first heat dissipation structure 517 is located on the second electrode 503 of the second side 505 of the piezoelectric layer 502, and... The second heat dissipation structure 518 extends through the piezoelectric layer 502 from the first side 504 and contacts the second electrode 503 on the second side 505 of the piezoelectric layer 502 facing the surface of the piezoelectric layer 502; or, the first heat dissipation structure 517 is located on the second electrode 503 on the second side 505 of the piezoelectric layer 502, and the second heat dissipation structure 518 extends through the piezoelectric layer 502 from the second side 505 and contacts the first electrode 501 on the first side 504 of the piezoelectric layer 502 facing the surface of the piezoelectric layer 502; or, the first heat dissipation structure 517 is located on the second electrode 503 on the second side 505 of the piezoelectric layer 502. On the second electrode 503 of side 505, a second heat dissipation structure 518 extends through the piezoelectric layer 502 from both sides and contacts the surfaces of the second electrode 503 and the first electrode 501 of the piezoelectric layer 502 facing the piezoelectric layer 502, respectively; or, the first heat dissipation structure 517 is located on the first electrode 501 and the second electrode 503 on both sides of the piezoelectric layer 502, and the second heat dissipation structure 518 extends through the piezoelectric layer 502 from the first side 504 and contacts the surface of the second electrode 503 of the second side 505 of the piezoelectric layer 502 facing the piezoelectric layer 502;Alternatively, the first heat dissipation structure 517 is located on the first electrode 501 and the second electrode 503 on both sides of the piezoelectric layer 502, and the second heat dissipation structure 518 penetrates the piezoelectric layer 502 from the second side 505 and contacts the surface of the first electrode 501 on the first side 504 of the piezoelectric layer 502 facing the piezoelectric layer 502; or, the first heat dissipation structure 517 is located on the first electrode 501 and the second electrode 503 on both sides of the piezoelectric layer 502, and the second heat dissipation structure 518 penetrates the piezoelectric layer 502 from both sides and contacts the surfaces of the second electrode 503 and the first electrode 501 of the piezoelectric layer 502 facing the piezoelectric layer 502, respectively.

[0177] In some embodiments, when the heat dissipation structure 514 includes a first heat dissipation structure 517 and a second heat dissipation structure 518, the first heat dissipation structure 517 is located on the first electrode 501 on the first side 504 of the piezoelectric layer 502, and the second heat dissipation structure 518 extends through the first side 504 of the piezoelectric layer 502 and contacts the second electrode 503 on the second side 505 of the piezoelectric layer 502 facing the surface of the piezoelectric layer 502.

[0178] As an example, when the material of the heat dissipation structure 514 is a metallic material, the step of forming the heat dissipation structure 514 at the junction of adjacent resonant units I includes: forming an adhesion seed layer 515 at the junction of adjacent resonant units I, the adhesion seed layer 515 being in contact with the first electrode 501 or the second electrode 503; forming a heat dissipation body structure 516 on the adhesion seed layer 515, thereby forming a heat dissipation structure 514 including the heat dissipation body structure 516 and the adhesion seed layer 515.

[0179] The adhesion seed layer 515 is used to enhance the adhesion between the heat dissipation body structure 516 and the piezoelectric stack structure 500. At the same time, the adhesion seed layer 515 is also used to provide a growth basis for the formation of the heat dissipation body structure 516 and to provide a uniform starting surface.

[0180] Therefore, in some embodiments, the adhesion seed layer 515 adopts a stacked structure of titanium and copper.

[0181] In some embodiments, continue to refer to Figure 9 In the step of forming the opening 519, an opening 519 is formed from either side of the piezoelectric layer 502, sequentially penetrating the dummy electrode 512 and the piezoelectric layer 502.

[0182] Therefore, in the step of forming the second heat dissipation structure 518 in the opening 519, the second heat dissipation structure 518 passes through the dummy electrode 512 and the piezoelectric layer 502 sequentially from the side where the dummy electrode 512 is located, and contacts the dummy electrode 512, so that the dummy electrode 512 is connected to the first electrode 501 or the second electrode 503 on the other side through the second heat dissipation structure 518, thereby making the dummy electrode 512 and the first electrode 501 or the second electrode 503 on the other side at the same potential. Therefore, no electric field is generated between the dummy electrode 512 and the first electrode 501 or the second electrode 503 on the other side, thereby reducing the probability of parasitic resonance between the dummy electrode 512 and the first electrode 501 or the second electrode 503 on the other side.

[0183] In some embodiments, continue to refer to Figure 9 The step of forming the opening 519 further includes forming the opening 519 at the edge of the piezoelectric stack structure 500.

[0184] Therefore, the step of forming the second heat dissipation structure 518 in the opening 519 further includes: forming an interconnect structure 520 in the opening 519 at the edge position of the piezoelectric stack structure 500, wherein the interconnect structure 520 and the heat dissipation structure 514 are located on the same side of the piezoelectric stack structure 500, and the interconnect structure 520 is in contact with either or both of the first electrode 501 and the second electrode 503.

[0185] The interconnect structure 520 is used for electrical connection with the subsequently formed signal electrode, which applies an electrical signal to the piezoelectric stack structure 500 through the interconnect structure 520.

[0186] Specifically, the interconnect structure 520 includes: a first interconnect structure 521 that penetrates the piezoelectric layer 502 and is connected to the second electrode 503; and a second interconnect structure 522 that penetrates the piezoelectric layer 502, one end of which is connected to the second electrode 503 and the other end of which is connected to the first electrode 501.

[0187] It should be noted that the second interconnect structure 522 located at the edge of the piezoelectric stack structure 500 short-circuits the first electrode 501 and the second electrode 503 located on both sides of the piezoelectric layer 502. This is beneficial to ensure that the first electrode 501 and the second electrode 503 located at the edge of the piezoelectric stack structure 500 are at the same potential. Therefore, no electric field is generated between the first electrode 501 and the second electrode 503 located at the edge of the piezoelectric stack structure 500, thereby reducing the probability of parasitic resonance between the first electrode 501 and the second electrode 503 located at the edge of the piezoelectric stack structure 500.

[0188] In some embodiments, when the interconnect structure 520 includes a second interconnect structure 522, the second electrode 503 located at the edge of the piezoelectric stack structure 500 is spaced apart from the second electrode 503 located away from the edge of the piezoelectric stack structure 500, or the first electrode 501 located at the edge of the piezoelectric stack structure 500 is spaced apart from the first electrode 501 located away from the edge of the piezoelectric stack structure 500. When the second interconnect structure 522 penetrating the piezoelectric layer 502 is subsequently formed, it is beneficial to reduce the risk of short circuits between the first electrode 501 and the second electrode 503 located on both sides of the piezoelectric layer 502 due to the second interconnect structure 522.

[0189] refer to Figure 11 After forming a heat dissipation structure 514 at the junction of adjacent resonant units I, the method further includes forming a first passivation layer 523 covering the surface of the heat dissipation structure 514 and the electrode layer surface of the piezoelectric layer 502 on the side away from the first substrate 511.

[0190] The first passivation layer 523 is used to protect the heat dissipation structure 514 and the electrode layer, which helps to prevent the heat dissipation structure 514 and the electrode layer from being exposed to the air, thereby reducing the probability of moisture and pollutants in the air adhering to the heat dissipation structure 514 and the electrode layer.

[0191] In some embodiments, the material of the first passivation layer 523 is silicon oxide.

[0192] Continue to refer to Figure 11 After the heat dissipation structure 514 is formed on the first side 504 of the piezoelectric layer 502, and before the heat dissipation electrode penetrating the first substrate 511 and the first support layer 509 is formed at the junction of the adjacent resonant units I, the method further includes: forming a second support layer 529 on the first side 504 of the piezoelectric layer 502, the second support layer 529 being located at the edge of the piezoelectric stack structure 500 and connected to the first support layer 509, the second support layer 529 and the piezoelectric stack structure 500 forming a second cavity 530.

[0193] The second support layer 529 is used to bond the second substrate 531.

[0194] The second cavity 530 helps reduce the vibration energy loss of the filter and improves the acoustic-electric conversion performance of the filter.

[0195] The material of the second support layer 529 can be an organic material or a metal material with strong adhesion.

[0196] Specifically, if the material of the second support layer 529 is a metal material, the metal material includes gold or copper-tin. Accordingly, the second support layer 529 can be bonded to the first side 504 of the piezoelectric layer 502 by gold-gold bonding or copper-tin bonding.

[0197] In some embodiments, the material of the second support layer 529 is a dry film. In other embodiments, the material of the second support layer may also be other photosensitive materials.

[0198] In some embodiments, the step of forming a second support layer 529 on the first side 504 of the piezoelectric layer 502 further includes: forming a second support layer 529 at the junction of adjacent resonant units I corresponding to the heat dissipation structure 514, and the second support layer 529 is connected to one or both of the first heat dissipation structure 517 and the second heat dissipation structure 518, and the second support layer 529 and the piezoelectric stack structure 500 form a second cavity 530.

[0199] It should be noted that the second support layer 529 at the junction of the adjacent resonant unit I corresponding to the heat dissipation structure 514 can further enhance the support effect at the position of the adjacent resonant unit I, thereby improving the structural stability of the filter.

[0200] As an example, the second support layer 529 is located at the edge of the piezoelectric stack structure 500 and at the junction of the adjacent resonant unit I corresponding to the second heat dissipation structure 517.

[0201] In other embodiments, depending on actual needs, the second support layer is located only at the edge of the piezoelectric stacked structure; or, the second support layer is located at the edge of the piezoelectric stacked structure and at the junction of the adjacent resonant units corresponding to the first heat dissipation structure; or, the second support layer is located at the edge of the piezoelectric stacked structure and at the junction of the adjacent resonant units corresponding to the first heat dissipation structure and the second heat dissipation structure, respectively.

[0202] Continue to refer to Figure 11 After the second support layer 529 is formed on the first side 504 of the piezoelectric layer 502, and before a heat dissipation electrode penetrating the first substrate 511 and the first support layer 509 is formed at the junction of adjacent resonant units I, the method further includes: bonding a second substrate 531 to the side of the second support layer 529 away from the piezoelectric layer 502, wherein the second substrate 531 seals the second cavity 530.

[0203] The second substrate 531 can be any suitable substrate known to those skilled in the art, such as at least one of the following materials: silicon, germanium, silicon germanium, silicon carbide, silicon carbide, indium arsenide, gallium arsenide, indium phosphide, or other III / V compound semiconductors, including multilayer structures composed of these semiconductors, or silicon on insulator, silicon on insulator, silicon on insulator, silicon on insulator with germanium, silicon with trap-rich layers, and germanium on insulator, or it can be a double-sided polished silicon wafer, or a ceramic substrate such as alumina, quartz, or glass substrate.

[0204] refer to Figures 12 to 14 After the first substrate 511 is bonded to the side of the first support layer 509 away from the piezoelectric layer 502, the method further includes: forming a heat dissipation electrode 524 penetrating the first substrate 511 and the first support layer 509 at the junction of adjacent resonant units I.

[0205] It should be noted that the heat generated by the vibration of the piezoelectric layer 502 in the resonant unit I can be transferred to the heat dissipation electrode 524 through the second electrode 503 and the heat dissipation structure 514. Then, the heat dissipation electrode 524 transfers the heat to the external environment, further enhancing the heat conduction effect of the resonant unit I located far from the edge of the piezoelectric stack structure 500.

[0206] Specifically, in the step of forming a heat dissipation electrode 524 that penetrates the first substrate 511 and the first support layer 509, the heat dissipation electrode 524 is in contact with the second electrode 503.

[0207] It should be noted that the heat dissipation electrode 524 is in contact with the second electrode 503, and the second electrode 503 is in contact with the heat dissipation structure 514. Therefore, the heat generated by the vibration of the piezoelectric layer 502 in the resonant unit I can be quickly transferred to the heat dissipation electrode 524 through the second electrode 503 and the heat dissipation structure 514.

[0208] In other embodiments, the heat dissipation electrode may not be in contact with the second electrode.

[0209] In some embodiments, the heat dissipation electrode 524 includes: a heat dissipation electrode body 525 located at the junction of adjacent resonant units I, the heat dissipation electrode body 525 penetrating the first substrate 511 and the first support layer 509; a first seed layer 526 covering the bottom and sidewalls of the heat dissipation electrode body 525, the first seed layer 526 being in contact with the second electrode 503; a first solder ball 527 located on the surface of the first substrate 511 facing away from the piezoelectric layer 502, corresponding to the heat dissipation electrode body 525; and a second seed layer 528 located between the heat dissipation electrode body 525 and the first solder ball 527.

[0210] The heat dissipation electrode body 525 serves as the main part of the heat dissipation electrode 524 and is used to transfer the heat generated by the vibration of the piezoelectric layer 502 in the resonant unit I to the external environment through the first solder ball 527.

[0211] In some embodiments, the heat dissipation electrode body 525 is made of a metallic material. The metallic material has good thermal conductivity, allowing the heat generated by the vibration of the piezoelectric layer 502 in the resonant unit I to be quickly transferred to the heat dissipation electrode body 525 via the second electrode 503 and the heat dissipation structure 514. The heat dissipation electrode body 525 then transfers the heat to the external environment via the first solder ball 527.

[0212] The first seed layer 526 is used to enhance the adhesion between the heat dissipation electrode body 525 and the first substrate 511, between the heat dissipation electrode body 525 and the first support layer 509, and between the heat dissipation electrode body 525 and the second electrode 503. At the same time, the first seed layer 526 is also used to provide a growth basis for the formation of the heat dissipation electrode body 525 and to provide a uniform starting surface.

[0213] Therefore, in some embodiments, the first seed layer 526 adopts a stacked structure of titanium and copper.

[0214] The second seed layer 528 is used to enhance the adhesion between the first solder ball 527 and the heat dissipation electrode body 525. At the same time, the second seed layer 528 is also used to provide a growth basis for the formation of the first solder ball 527 and to provide a uniform starting surface.

[0215] The second seed layer 528 also adopts a stacked structure of titanium and copper.

[0216] The first solder ball 527 serves as the connection point between the heat dissipation electrode 524 and the package structure, and is responsible for conducting heat to the external environment.

[0217] In some embodiments, in the step of forming a heat dissipation electrode 524 penetrating the first substrate 511 and the first support layer 509 at the junction of adjacent resonant units I, the position of the heat dissipation electrode 524 corresponds one-to-one with the position of the heat dissipation structure 514 along the thickness direction of the piezoelectric stack structure 500.

[0218] It should be noted that since the position of the heat dissipation electrode 524 corresponds one-to-one with the position of the heat dissipation structure 514, the heat generated by the vibration of the piezoelectric layer 502 in the resonant unit I can be directly conducted from the heat dissipation structure 514 to the heat dissipation electrode 524 without going through an extra heat conduction path, thereby improving the heat dissipation efficiency.

[0219] In other embodiments, depending on actual needs, the position of the heat dissipation electrode and the position of the heat dissipation structure may not correspond one-to-one along the thickness direction of the piezoelectric stack structure.

[0220] In some embodiments, the step of forming a heat dissipation electrode 524 penetrating the first substrate 511 and the first support layer 509 at the junction of adjacent resonant units I further includes: forming a signal electrode 532 penetrating the first support layer 509 and the first substrate 511 at the edge of the piezoelectric stack structure 500, wherein the signal electrode 532 is in contact with the second electrode 503.

[0221] During the operation of the filter, the signal electrode 532 is used as the input or output of the signal.

[0222] Specifically, the signal electrode 532 and the heat dissipation electrode 524 are formed in the same step, which helps to simplify the process complexity and improve work efficiency.

[0223] The signal electrode 532 includes: a signal electrode body 533 located at the edge of the piezoelectric stack structure 500, the signal electrode body 533 penetrating the first substrate 511 and the first support layer 509; a third seed layer 534 covering the bottom and sidewalls of the signal electrode body 533, the third seed layer 534 being in contact with the second electrode 503; a second solder ball 538 located on the surface of the first substrate 511 facing away from the piezoelectric layer 502, in contact with the signal electrode body 533; and a fourth seed layer 535 located between the signal electrode body 533 and the second solder ball 538.

[0224] Specifically, the steps for forming the heat dissipation electrode 524 and the signal electrode 532 include: (Refer to...) Figure 12 A groove 536 is formed at the edge of the piezoelectric stack structure 500 and at the junction of adjacent resonant units I, penetrating the first substrate 511 and the first support layer 509; Reference Figure 13 A third seed layer 534 is formed on the sidewall and bottom of the groove 536 at the edge of the piezoelectric stack structure 500. A signal electrode body 533 is formed on the third seed layer 534. A first seed layer 526 is formed on the sidewall and bottom of the groove 536 at the junction of adjacent resonant units I. A heat dissipation electrode body 525 is formed on the first seed layer 526. (Reference) Figure 14 A fourth seed layer 535 is formed on the surface of the first substrate 511 at the edge of the piezoelectric stack structure 500 on the side facing away from the piezoelectric layer 502, and a second seed layer 528 is formed on the surface of the first substrate 511 at the junction of the adjacent resonant units I on the side facing away from the piezoelectric layer 502; Continuing to refer to Figure 14A second solder ball 538 is formed on the fourth seed layer 535, and a first solder ball 527 is formed on the second seed layer 528.

[0225] It should be noted that after forming the signal electrode body 533 and the heat dissipation electrode body 525, a fourth seed layer 535 is formed on the surface of the first substrate 511 away from the piezoelectric layer 502 at the edge of the piezoelectric stack structure 500, and before forming the second seed layer 528 on the surface of the first substrate 511 away from the piezoelectric layer 502 at the junction of the adjacent resonant units I, the process further includes: forming a second passivation layer 537 covering the surface of the heat dissipation electrode body 525 and the surface of the first substrate 511 away from the piezoelectric layer 502, wherein the second passivation layer 537 exposes a portion of the width of the heat dissipation electrode body 525 and the signal electrode body 533.

[0226] The second passivation layer 537 is used to protect the heat dissipation electrode body 525 and the signal electrode body 533, which helps to prevent the heat dissipation electrode body 525 and the signal electrode body 533 from being exposed to the air, thereby reducing the probability of moisture and pollutants in the air adhering to the heat dissipation electrode body 525 and the signal electrode body 533.

[0227] In some embodiments, the material of the second passivation layer 537 is photoresist.

[0228] It should be noted that since the heat dissipation electrode body 525 and the signal electrode body 533 are made of metal, and the second passivation layer 537 needs to expose a portion of the width of the heat dissipation electrode body 525 and the signal electrode body 533, using photoresist as the second passivation layer 537 can expose the heat dissipation electrode body 525 and the signal electrode body 533 through exposure and development, without the need for etching, which helps to reduce the probability of metal contamination of the etching equipment.

[0229] The filter structure of this embodiment can be formed using the filter structure formation method of the aforementioned embodiment, or it can be formed using other filter structure formation methods, which will not be described again in this embodiment.

[0230] Accordingly, embodiments of the present invention also provide an electronic device, which includes the filter described in any embodiment of the present invention.

[0231] For a detailed description of the filter structure, please refer to the detailed description of the foregoing embodiments, which will not be repeated in this embodiment.

[0232] Filters can be integrated into various electronic devices. As the foregoing analysis shows, filters offer high performance, which in turn enables high-performance electronic devices. These electronic devices can include personal computers, smartphones and other mobile terminals, media players, navigation devices, video game consoles, game controllers, tablet computers, wearable devices, security access control systems, POS terminals, medical devices, flight simulators, and more.

[0233] While the above disclosure is provided, it is not limited thereto. Any person skilled in the art may make various alterations and modifications without departing from the spirit and scope of this disclosure; therefore, the scope of protection of this disclosure shall be determined by the scope defined in the claims.

Claims

1. A filter, characterized in that, include: A piezoelectric stack structure includes a first electrode, a piezoelectric layer, and a second electrode stacked together. The piezoelectric layer includes a first side and a second side disposed opposite to each other. The first electrode is located on the first side, and the second electrode is located on the second side. Along a plane direction perpendicular to the thickness direction of the piezoelectric stack structure, the piezoelectric stack structure includes a plurality of resonant units. A heat dissipation structure is located at the junction of adjacent resonant units, and the heat dissipation structure is in contact with either the first electrode or the second electrode, or the heat dissipation structure is in contact with both the first electrode and the second electrode; the heat dissipation structure includes a first heat dissipation structure and a second heat dissipation structure; wherein, the first heat dissipation structure is located on the first electrode or the second electrode on either side of the piezoelectric layer, and the first heat dissipation structure is in contact with the first electrode or the second electrode located on the same side of the piezoelectric layer; the second heat dissipation structure penetrates the piezoelectric layer from either side of the piezoelectric layer and is in contact with the surface of the second electrode or the first electrode on the other side of the piezoelectric layer facing the piezoelectric layer; The piezoelectric stack structure further includes: a dummy electrode located on either side of the piezoelectric layer or on both sides of the piezoelectric layer, wherein the dummy electrode and the first electrode or second electrode located on the same side of the piezoelectric layer are made of the same material and are in the same layer, and the dummy electrode and the first electrode or second electrode on the same side are spaced apart; a second heat dissipation structure passes through the dummy electrode and the piezoelectric layer sequentially from the side where the dummy electrode is located, and is in contact with the dummy electrode; thereby connecting the dummy electrode to the first electrode or second electrode on the other side through the second heat dissipation structure, so that the dummy electrode and the first electrode or second electrode on the other side are at the same potential.

2. The filter as described in claim 1, characterized in that, When the heat dissipation structure includes a second heat dissipation structure, and the second heat dissipation structure only penetrates the piezoelectric layer, the material of the heat dissipation structure includes one or more of the following: metallic materials, silicon carbide, diamond, and graphene. Alternatively, if the heat dissipation structure includes a second heat dissipation structure, and the second heat dissipation structure sequentially penetrates the dummy electrode and the piezoelectric layer, the material of the heat dissipation structure includes a metallic material.

3. The filter as described in claim 1, characterized in that, When the heat dissipation structure includes a first heat dissipation structure, the material of the heat dissipation structure includes one or more of the following: metallic materials, silicon carbide, diamond, and graphene.

4. The filter as described in claim 2 or 3, characterized in that, When the material of the heat dissipation structure is a metallic material, the metallic material includes one or more of aluminum, titanium copper, molybdenum, tungsten, and gold.

5. The filter as described in claim 2 or 3, characterized in that, When the material of the heat dissipation structure is a metallic material, the heat dissipation structure includes a heat dissipation main structure and an adhesion seed layer located between the heat dissipation main structure and the piezoelectric stack structure, wherein the adhesion seed layer is in contact with the first electrode or the second electrode.

6. The filter as described in claim 1, characterized in that, The filter further includes: a first support layer located on the surface of the second electrode facing away from the piezoelectric layer, and located at the edge of the piezoelectric stack structure and the junction of adjacent resonant units, the first support layer and the piezoelectric stack structure forming a first cavity; and a first substrate located on the side of the first support layer away from the piezoelectric layer, the first substrate sealing the first cavity. The filter further includes a heat dissipation electrode located at the junction of adjacent resonant units, the heat dissipation electrode penetrating the first substrate and the first support layer.

7. The filter as described in claim 6, characterized in that, The heat dissipation electrode is in contact with the second electrode.

8. The filter as described in claim 6, characterized in that, Along the thickness direction of the piezoelectric stack, the position of the heat dissipation electrode corresponds one-to-one with the position of the heat dissipation structure.

9. The filter as described in claim 6, characterized in that, The filter further includes: a second support layer located on the first side of the piezoelectric layer and at the edge of the piezoelectric stack structure, wherein the second support layer is connected to the first support layer, and the second support layer and the piezoelectric stack structure form a second cavity.

10. The filter as described in claim 9, characterized in that, The second support layer is also located at the junction of the adjacent resonant units corresponding to the heat dissipation structure, and the second support layer is connected to one or both of the first heat dissipation structure and the second heat dissipation structure. The second support layer and the piezoelectric stack structure form a second cavity.

11. The filter as described in claim 9 or 10, characterized in that, The filter further includes a second substrate located on the side of the second support layer away from the piezoelectric layer, the second substrate sealing the second cavity.

12. A method for forming a filter, characterized in that, include: A piezoelectric stack structure is provided, the piezoelectric stack structure includes a first electrode, a piezoelectric layer and a second electrode stacked together, the piezoelectric layer includes a first side and a second side disposed opposite to each other, the first electrode is located on the first side and the second electrode is located on the second side, and the piezoelectric stack structure includes a plurality of resonant units along a plane direction perpendicular to the thickness direction of the piezoelectric stack structure; A heat dissipation structure is formed at the junction of adjacent resonant units, and the heat dissipation structure is in contact with either the first electrode or the second electrode, or the heat dissipation structure is in contact with both the first electrode and the second electrode. In the step of forming the heat dissipation structure at the junction of adjacent resonant units, the heat dissipation structure includes one or both of a first heat dissipation structure and a second heat dissipation structure. The step of forming the first heat dissipation structure includes: forming the first heat dissipation structure on the first electrode or the second electrode on either side of the piezoelectric layer, and the first heat dissipation structure is in contact with the first electrode or the second electrode located on the same side of the piezoelectric layer; The step of forming the second heat dissipation structure includes: forming an opening through the piezoelectric layer from either side of the piezoelectric layer, the opening exposing the surface of the second electrode or the first electrode facing the piezoelectric layer on the other side of the piezoelectric layer; forming a second heat dissipation structure in the opening, the second heat dissipation structure being in contact with the second electrode or the first electrode exposed by the opening; After providing the piezoelectric stacked structure, before forming the second heat dissipation structure at the junction of adjacent resonant units, the method further includes: forming a dummy electrode on either side of the piezoelectric layer or on both sides of the piezoelectric layer, wherein the dummy electrode and the first electrode or the second electrode located on the same side of the piezoelectric layer are made of the same material as the first electrode or the second electrode located on the same side of the piezoelectric layer, and the dummy electrode and the first electrode or the second electrode on the same side are spaced apart. In the step of forming the opening, an opening is formed from either side of the piezoelectric layer, sequentially penetrating the dummy electrode and the piezoelectric layer, so that the dummy electrode is connected to the first electrode or the second electrode on the other side through the second heat dissipation structure, thereby making the dummy electrode and the first electrode or the second electrode on the other side at the same potential.

13. The method for forming a filter as described in claim 12, characterized in that, In the case where the heat dissipation structure includes the first heat dissipation structure and the second heat dissipation structure, in the step of forming the second heat dissipation structure in the opening, the first heat dissipation structure is simultaneously formed on the first electrode or the second electrode on the same side of the piezoelectric layer.

14. The method for forming a filter as described in claim 12, characterized in that, In the step of forming the heat dissipation structure at the junction of adjacent resonant units, if the heat dissipation structure includes a second heat dissipation structure and the second heat dissipation structure only penetrates the piezoelectric layer, the material of the heat dissipation structure includes one or more of metallic materials, silicon carbide, diamond, and graphene. Alternatively, if the heat dissipation structure includes a second heat dissipation structure, and the second heat dissipation structure sequentially penetrates the dummy electrode and the piezoelectric layer, the material of the heat dissipation structure includes a metallic material.

15. The method for forming a filter as described in claim 12, characterized in that, In the step of forming the heat dissipation structure at the junction of adjacent resonant units, if the heat dissipation structure includes a first heat dissipation structure, the material of the heat dissipation structure includes one or more of metallic materials, silicon carbide, diamond, and graphene.

16. The method for forming a filter as described in claim 14 or 15, characterized in that, The metallic material includes one or more of aluminum, titanium copper, molybdenum, tungsten, and gold.

17. The method for forming a filter as described in claim 14 or 15, characterized in that, When the material of the heat dissipation structure is a metallic material, the step of forming the heat dissipation structure at the junction of adjacent resonant units includes: forming an adhesion seed layer at the junction of adjacent resonant units, the adhesion seed layer being in contact with the first electrode or the second electrode; forming a heat dissipation body structure on the adhesion seed layer, thus forming a heat dissipation structure including the heat dissipation body structure and the adhesion seed layer.

18. The method for forming a filter as described in claim 12, characterized in that, After providing the piezoelectric stacked structure, and before forming a heat dissipation structure on the first side of the piezoelectric layer, the method further includes: forming a first support layer on the surface of the second electrode facing away from the piezoelectric layer, the first support layer being located at the edge of the piezoelectric stacked structure and at the junction of adjacent resonant units, the first support layer and the piezoelectric stacked structure forming a first cavity; after forming the first support layer on the surface of the second electrode facing away from the piezoelectric layer, bonding a first substrate to the side of the first support layer away from the piezoelectric layer, the first substrate sealing the first cavity; After bonding the first substrate to the side of the first support layer away from the piezoelectric layer, the method further includes: forming a heat dissipation electrode penetrating the first substrate and the first support layer at the junction of adjacent resonant units.

19. The method for forming a filter as described in claim 18, characterized in that, In the step of forming a heat dissipation electrode that penetrates the first substrate and the first support layer, the heat dissipation electrode is in contact with the second electrode.

20. The method for forming a filter as described in claim 18, characterized in that, The step of forming a heat dissipation electrode penetrating the first support layer and the first substrate at the junction of adjacent resonant units further includes: forming a signal electrode penetrating the first support layer and the first substrate at the edge of the piezoelectric stack structure, wherein the signal electrode is in contact with the second electrode.

21. The method for forming a filter as described in claim 18, characterized in that, After the heat dissipation structure is formed on the first side of the piezoelectric layer, and before the heat dissipation electrode penetrating the first substrate and the first support layer is formed at the junction of adjacent resonant units, the method further includes: forming a second support layer on the first side of the piezoelectric layer, the second support layer being located at the edge of the piezoelectric stack structure and connected to the first support layer, the second support layer and the piezoelectric stack structure forming a second cavity.

22. The method for forming a filter as described in claim 21, characterized in that, The step of forming the second support layer on the first side of the piezoelectric layer further includes: forming the second support layer at the junction of the adjacent resonant units corresponding to the heat dissipation structure, and the second support layer is connected to one or both of the first heat dissipation structure and the second heat dissipation structure, and the second support layer and the piezoelectric stack structure form a second cavity.

23. The method for forming a filter as described in claim 21 or 22, characterized in that, After the step of forming the second support layer on the first side of the piezoelectric layer, and before forming a heat dissipation electrode penetrating the first substrate and the first support layer at the junction of adjacent resonant units, the method further includes: bonding a second substrate to the side of the second support layer away from the piezoelectric layer, wherein the second substrate seals the second cavity.

24. The method for forming a filter as described in claim 18, characterized in that, In the step of forming a heat dissipation electrode penetrating the first substrate and the first support layer at the junction of adjacent resonant units, the position of the heat dissipation electrode corresponds one-to-one with the position of the heat dissipation structure.

25. An electronic device, characterized in that, Includes the filter as described in any one of claims 1 to 11.

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