Multi-level stacked acoustic wave (AW) filter packages and related fabrication methods

Abstract

A multilayer stacked AW filter package, comprising a first AW filter stacked on a second AW filter, employs a semiconductor manufacturing method and structure, including a metallization layer containing interconnects for coupling contact surfaces to the second AW filter. Each AW filter includes AW filter circuitry on a semiconductor substrate. A second substrate disposed on a frame on the substrate protects the AW filter circuitry. In the multilayer AW filter package, the second substrate of the first AW filter comprises a glass substrate having a coefficient of thermal expansion similar to that of the semiconductor substrate. Interconnects coupling the second AW filter to the contact surfaces are disposed on an insulator on the sidewall surface of the semiconductor substrate of the first AW filter for isolation. In a stacked AW filter package comprising a single AW filter, the interconnects couple the contact surface to that AW filter.

Description

Technical Field

[0001] This case relates to acoustic wave (AW) filter packaging, including an AW filter having AW filter circuitry on a substrate and a substrate stacked including AW filter circuitry. Prior Technology

[0002] Manufacturers of mobile wireless devices can make new devices attractive to buyers by enhancing the functionality of each generation. Enhancing device capabilities typically requires adding more circuitry, which occupies more space, but the size of handheld devices, such as those based on the size of a human hand, remains constant. Methods for achieving functional enhancements without increasing device size include reducing the size of the circuitry providing the functionality, allowing more circuitry to fit into the device's internal space. Reducing the area of ​​transistors and wires increases circuit density, making it possible to reduce the size of semiconductor wafers or place more circuitry on a given size semiconductor wafer. Another method for increasing the number of integrated circuits (ICs) in a package is three-dimensional (3D) IC stacking. With this method, the area previously occupied by two ICs placed side-by-side can be reduced (e.g., halved) by vertically stacking one IC onto another in the same horizontal area, resulting in only a small increase in package height. The active circuitry in stacked ICs is encased in layers of metal, dielectric material, insulator, and / or molding compound, and stacking ICs in a package may not significantly interfere with their operation.

[0003] Handheld devices also include wireless devices containing radio frequency (RF) circuitry. RF circuitry includes analog filters conventionally configured as AW (Audio Wave) filter circuits. Examples of AW filter circuits include surface acoustic wave (SAW) filter circuits and bulk acoustic wave (BAW) filter circuits. AW filter circuits convert electrical input signals into acoustic waves in a piezoelectric material. In one example, a SAW filter circuit includes a first interdigital transducer (IDT) on the surface of the piezoelectric material configured to receive an RF signal and a second IDT on the same surface configured to generate a filtered RF signal. The RF signal is converted into acoustic waves that propagate through the surface of the piezoelectric material from the first IDT to the second IDT. The acoustic waves in the SAW filter circuit need to be protected from physical contact, which could interfere with wave propagation. This protection is provided by providing a cavity or gap above the surface of the substrate. Because such cavities are necessary for protecting the AW filter circuitry and are not required in stacked ICs, AW filter devices are not stacked using conventional methods used in 3D IC stacking. Summary of the Invention

[0004] The exemplary embodiments disclosed in the detailed description include multilayer stacked acoustic wave (AW) filter packages, which include structures for supporting stacked AW filters. Related manufacturing methods are also disclosed. Certain structures and manufacturing methods for supporting multilayer stacked AW filter packages disclosed herein can also be used in AW filter packages that include only a single AW filter. In this regard, the AW filter package disclosed herein includes one or more AW filters, each AW filter including a first substrate, the first substrate including a first surface (e.g., piezoelectric material) on which at least one AW filter circuit is disposed. Each AW filter circuit includes first and second interdigitated transducers (IDTs) to provide radio frequency (RF) signal filtering. Each AW filter also includes a frame coupled to the first substrate and surrounding at least one AW filter circuit. A second substrate (e.g., a cover substrate) disposed on the frame surrounds an air cavity within the frame between the first substrate and the second substrate. In one exemplary embodiment, the AW filter package includes a multilayer AW filter package comprising a plurality of AW filters stacked vertically in a stacked arrangement to include a plurality of filter circuits for filtering a plurality of frequencies or frequency bands. A multilayer AW filter package includes a first top AW filter (including at least a first AW filter circuit) disposed on a first substrate and a second substrate disposed on a first frame on the first substrate. The first substrate disposed on the second frame on a third substrate surrounds a second bottom AW filter including at least a second AW filter circuit to form a multilayer AW filter package. The first substrate and the third substrate may be formed of semiconductor material to serve as semiconductor substrates. Manufacturing the first substrate and the third substrate as semiconductor substrates allows the use of semiconductor manufacturing processes and technologies used to manufacture semiconductor die packages to manufacture the AW filter package.

[0005] In a first exemplary configuration of a multilayer AW filter package, the metal interconnects provided for the first AW filter are separate from the metal interconnects provided for the second AW filter to provide separate signal paths for receiving RF signals from contact pads on the contact surface of the second substrate in their respective AW filter circuits and for providing their respective filtered RF signals to the contact pads on the contact surface. In this configuration, the first metal interconnect, in the form of a metallized vertical interconnect channel (via), is configured to pass through the second substrate to the surface of the first substrate to provide an interconnect path for the first top AW filter. Furthermore, a metallization layer including a second metal interconnect is formed on the outer peripheral wall of the stacked AW filter to provide a physically and electrically separate interconnect path from the interconnect path of the first top AW filter for the AW filter circuit of the second bottom AW filter. The second metal interconnect of this metallization layer provides an interconnect path between the first contact pads on the contact surface of the second substrate of the second bottom AW filter circuit and the first top AW filter. Forming the interconnect path of the AW filter in the AW filter package as a metal interconnect in a metallization layer (such as a redistribution layer (RDL)) allows the AW filter package to be manufactured using a metallization layer manufacturing process (e.g., an RDL manufacturing process). Metal interconnects in the metallization layer can be used to provide metal interconnects for interconnect paths of AW filters, even in AW filter packages that include only a single AW filter and not stacked AW filters. Furthermore, in an example of a multilayer AW filter package, the sidewall surfaces of the second, first, and third substrates can be staggered in the horizontal direction to support the formation of a metallization layer on the outer peripheral wall of the stacked AW filter to provide interconnect paths from contact pads on the contact surface of the second substrate to the second bottom AW filter circuitry. The staggered sidewall surfaces create a shoulder region extending outward from the second substrate on the first substrate, and in the multilayer AW filter package, a lower shoulder region extending outward from the first substrate of the AW filter package is created on the third substrate. The staggered sidewall surfaces support the formation of metal interconnects on the outer peripheral wall of the stacked AW filter and avoid overlap of "negative exposure" areas where metal interconnects cannot be formed.

[0006] In another exemplary embodiment of a multilayer AW filter package, metal interconnects (e.g., RDL interconnects) are formed on the outer peripheral wall of the stacked AW filter to provide an interconnect path from the contact surface of the second substrate to the second bottom AW filter. This interconnect path necessarily extends to the outer wall of the first substrate of the first top AW filter and then downwards to the third substrate of the second bottom AW filter. The first substrate of the first top AW filter is disposed between the second substrate and the third substrate of the second bottom AW filter. Therefore, electrical signals carried in the second metal interconnects in the interconnect path from the contact pads on the second substrate down to the third substrate of the second AW filter can form electrical contacts with the first substrate of the first top AW filter, resulting in a leakage current path between the second metal interconnects and at least one AW filter circuit of the first top AW filter. The leakage current can interfere with the performance of the AW filter circuits on the first and third substrates. In another exemplary embodiment, one or more insulating layers are disposed on the outer peripheral wall of the stacked AW filter between the first substrate and the second metal interconnect. The second metal interconnect is formed on top of one or more insulating layers disposed on the outer peripheral wall of the stacked AW filter. In this way, the electrical signals carried by the second metal interconnect are isolated and insulated from the first substrate of the first top AW filter.

[0007] In another exemplary embodiment of the AW filter package, the second substrate of the first top AW filter can be made of a glass material that can be laser-treated to allow precise openings to be formed in the second substrate to form metallized vias for the first metal interconnect to the first AW filter circuitry. The glass second substrate also advantageously provides mechanical robustness and stability to the AW filter package. For example, the coefficient of thermal expansion (CTE) of glass is higher than that of polymer materials conventionally used to form the second substrate. Particularly for stacked multilayer AW filter packages in which multiple AW filter cavities are formed on each substrate in a stacked arrangement, providing mechanical stability to the AW filter package to avoid any breakage of the second or first substrate due to deflection within the filter cavities is important. Furthermore, using a glass second substrate can provide mechanical stability to a substrate with reduced thickness, which is essential to keeping the overall height of the AW filter package within a desired height budget.

[0008] In one exemplary embodiment, a stacked AW filter package is disclosed. The stacked AW filter package includes: a first substrate including a first surface; AW filter circuitry on the first surface of the first substrate; a frame disposed on the first surface of the first substrate; a second substrate including a contact surface and a sidewall surface, the second substrate being disposed on the frame to form a cavity between the AW filter circuitry and the second substrate; and a metallization layer including at least one metal interconnect coupled to the contact surface of the second substrate and the first surface of the first substrate, the at least one metal interconnect being disposed on the sidewall surface of the second substrate.

[0009] In another exemplary embodiment, a method for manufacturing a stacked AW filter package is disclosed. The method includes: forming a first substrate including a first surface; forming an AW filter circuit on the first surface of the first substrate; forming a frame on the first surface of the first substrate; forming a second substrate including a contact surface and a sidewall surface; disposing the second substrate on the frame to form a cavity between the AW filter circuit and the second substrate; and forming a metallization layer including at least one metal interconnect coupled to the contact surface of the second substrate and the first surface of the first substrate, the at least one metal interconnect being disposed on the sidewall surface of the second substrate.

[0010] In another exemplary embodiment, a stacked AW filter package is disclosed. The stacked AW filter package includes: a first substrate including a first surface and a sidewall surface; a first AW filter circuit on the first surface of the first substrate; a first frame disposed on the first surface of the first substrate; a second substrate including a contact surface and a sidewall surface, the second substrate being stacked on the first frame to form a cavity between the first AW filter circuit and the second substrate; a third substrate including a second AW filter circuit on a second surface of the third substrate; a second frame disposed on the second surface of the third substrate; the first substrate disposed on the second frame to form a second cavity between the second AW filter circuit and the first substrate; a metallization layer including at least one metal interconnect coupled to the contact surface of the second substrate and the second surface of the third substrate, the at least one metal interconnect being disposed on the sidewall surface of the first substrate; and an insulator disposed on the sidewall surface of the first substrate and between the sidewall surface of the first substrate and the at least one metal interconnect.

[0011] In another exemplary embodiment, a method for manufacturing a stacked AW filter package is disclosed. The method includes: forming a first substrate including a first surface and a sidewall surface; forming a first AW filter circuit on the first surface of the first substrate; forming a first frame on the first surface of the first substrate; forming a second substrate including a contact surface and a sidewall surface; disposing the second substrate on the first frame to form a first cavity between the first AW filter circuit and the second substrate; forming a third substrate, the third substrate including a second AW filter circuit on a second surface of the third substrate; forming a second frame on the second surface of the third substrate; disposing the first substrate on the second frame to form a second cavity between the second AW filter circuit and the first substrate; forming an insulator on the sidewall surface of the first substrate; and forming a metallization layer including at least one metal interconnect coupled to the contact surface of the second substrate and the second surface of the third substrate, the at least one metal interconnect being disposed on the insulator on the sidewall surface of the first substrate. Simple Explanation of the Diagram

[0012] Figure 1 illustrates an example of a surface acoustic wave (SAW) device that can be used in a stacked acoustic wave (AW) filter package;

[0013] Figures 2A-2C are cross-sectional side views of a multilayer stacked AW filter package, which includes: a first substrate of a first top AW filter, a second substrate stacked on the first substrate, the first substrate stacked on a third substrate of a second bottom AW filter, and metal interconnects in a metallization layer on the outer peripheral wall of the stacked AW filter, the metal interconnects coupling the second bottom AW filter to contact pads on the second substrate.

[0014] Figure 3 illustrates an AW filter in a stacked AW filter package, which includes a second substrate stacked on a frame on a first surface of a substrate to form a cavity over the AW filter circuitry on the substrate.

[0015] Figure 4 is a flowchart illustrating the process of manufacturing the stacked AW filter package shown in Figure 3, including stacking a second substrate on a first frame on a first substrate to form a cavity over the AW filter circuit on the first substrate;

[0016] Figures 5A and 5B are flowcharts illustrating the process of manufacturing the stacked AW filter package shown in Figures 2A-2C, including forming an insulator between the outer peripheral wall of the stacked AW filter and the metal interconnects extending between the contact pads on the third and second substrates to prevent leakage current;

[0017] Figure 6 is a top view of the frame on the surface of the substrate in the AW filter package shown in Figures 2A-2C and 3;

[0018] Figure 7 is a top perspective view of an example of the AW filter circuit illustrated in Figures 2A-2C;

[0019] Figure 8 is a block diagram of an exemplary wireless communication device, including a radio frequency (RF) module comprising an AW filter package. The AW filter package includes a first AW filter circuitry on the first substrate protected within a cavity by a second substrate stacked on a frame on a first substrate, and also includes an insulator between the first substrate and a metal interconnect extending from contact pads on the second substrate to a third substrate stacked on the back side of the first substrate, as illustrated in Figures 2A-2C, 3, and 7; and

[0020] Figure 9 is a block diagram of an exemplary processor-based system that may include an AW filter package including a first AW filter circuit on the substrate protected within a cavity by a second substrate on a frame stacked on a first substrate, and also including an insulator between the first substrate and a metal interconnect extending from contact pads on the second substrate to a third substrate stacked on the back side of the substrate, as illustrated in Figures 2A-2C, 3 and 7 and according to any of the configurations disclosed herein. Implementation

[0021] Now, with reference to the accompanying drawings, several exemplary forms of this case are described. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any form described herein as "exemplary" is not necessarily to be construed as superior to or better than other forms.

[0022] Before discussing an exemplary configuration of a stacked AW filter package having one or more surface acoustic wave (SAW) filters (each AW filter comprising at least one AW filter on a first substrate and a second substrate (e.g., a cover substrate) disposed on a frame to provide a protective cavity over the AW filter circuitry) as illustrated in Figures 2A-2C, let’s discuss Figure 1. Figure 1 is an illustration of a surface acoustic wave (SAW) filter circuitry 100 on a first substrate 102 that may be employed in an AW filter 104 within a stacked AW filter package. Although not shown here, the AW filter 104 will include a second substrate disposed on a frame on the first substrate 102 to form a cavity to protect the AW filter circuitry 100 from acoustic interference, as disclosed herein. In this regard, Figure 1 is a perspective view of the AW filter 104 configured to allow certain frequency ranges of an input radio frequency (RF) signal to pass through while simultaneously blocking other frequencies. For example, the AW filter 104 may be included in another integrated circuit (IC) package comprising an RF transmit / receive circuitry system and an antenna, wherein the SAW filter circuitry 100 is used to filter the transmitted and / or received RF signals. In this example, the first substrate 102 includes a piezoelectric material 106 forming a first surface 108. A first interdigital transducer (IDT) 110(1) is disposed on the first surface 108 of the first substrate 102 as an input circuit. A second IDT 110(2) is also disposed on the first surface 108 of the first substrate 102 as an output circuit adjacent to the first IDT 110(1). The first IDT 110(1) is configured to receive an input RF signal 112 via first metal interconnects 114A and 114B coupled to first metal contacts 116A and 116B, respectively. The first metal contacts 116A and 116B (e.g., solder bumps, solder balls) on the first substrate 102 are connected to the first IDT(1). The first IDT 110(1) includes interdigitated metal interconnects 118A, 118B (e.g., metal lines, metal traces) and is configured to convert a received electrical input RF signal 112 into an acoustic wave that propagates from the first IDT 110(1) to the second IDT 110(2) on a first surface 108 of the first substrate 102. The first IDT 110(1) is configured to emit the acoustic wave on the first surface 108, and the second IDT 110(2) is configured to receive the filtered acoustic wave and convert it into a filtered RF signal 120. The second IDT 110(2) includes interdigitated metal interconnects 122A, 122B coupled to second metal contacts 124A, 124B, respectively, which provide the filtered RF signal 120 to the second metal interconnects 126A, 126B. In some examples, the SAW substrate corresponding to the first substrate 102 may include a plurality of SAW filter circuits 100. Similarly, a bulk acoustic wave (BAW) substrate may include multiple BAW filter circuits.

[0023] The exemplary configuration disclosed herein supports a multilayer stacked AW filter package 20 as shown in the cross-sectional side views of Figures 2A-2C, which includes a first top AW filter 202 ("first AW filter 202") and a second bottom AW filter 204 ("second AW filter 204"), each including a first substrate 206 and a third substrate 212. The first substrate 206 includes at least one first AW filter circuit 208 disposed on its first surface 210, and the third substrate 212 includes at least one second AW filter circuit 214 disposed on its second surface 216. The first substrate 206 and the third substrate 212 respectively include the first AW filter circuit 208 and the second AW filter circuit 214 disposed thereon. The multilayer stacked AW filter package 200 may also be referred to herein as a "stacked AW filter package 200" or "AW filter package 200".

[0024] The first AW filter circuit 208 and the second AW filter circuit 214 each provide RF signal filtering. The first AW filter 202 includes a first frame 218 coupled to a first substrate 206 and surrounding at least one first AW filter circuit 208. A second substrate 220 disposed on the first frame 218 surrounds a first cavity 222 (e.g., a gas cavity) above the first AW filter circuit 208, inside the first frame 218, and between the first substrate 206 and the cover substrate 220. The second substrate 220 is formed by a cover structure, which may also be referred to herein as "cover substrate 220", on the first frame 218. The second AW filter 204 includes a second frame 224 coupled to a third substrate 212 and surrounding at least one second AW filter circuit 214. The first substrate 206 of the first AW filter 202 is disposed on the second frame 224 to provide a cover structure surrounding a second cavity 226 (e.g., a gas cavity) between the first substrate 206 and the third substrate 212 inside the second frame 224. Therefore, the multilayer AW filter package 200 includes multiple AW filters stacked vertically in a stacked manner to include multiple filter circuits for filtering multiple frequencies or frequency bands.

[0025] The first substrate 206 and the third substrate 212 may be formed of a semiconductor material as a semiconductor substrate 213 to take advantage of the semiconductor manufacturing processes and technologies used to manufacture semiconductor die packages, which may be less expensive than conventional processes in which the substrate is formed of a piezoelectric material. Manufacturing the first substrate 206 and the third substrate 212 includes forming the semiconductor substrate 213, such as a silicon substrate, wherein the first and second surfaces 210, 216 include a piezoelectric material 228. The piezoelectric material 228 may be any suitable piezoelectric material disposed on the first substrate 206 and the third substrate 212, including but not limited to: quartz, lithium tantalate (LiTaO3), lithium niobate (LiNbO3), aluminum nitride (AlN), scandium-doped AlN (AlNSc), barium titanate (BaTiO3), and zinc oxide (ZnO).

[0026] In the multilayer AW filter package 220, a first metal interconnect 230 provides an interconnect path ("signal path") 232 for the first AW filter to receive RF signals and transmit filtered RF signals to the contact surface 234 of the cover substrate 220. The first metal interconnect 230 is separate from at least one second metal interconnect 236 that provides a signal path 238 for the second AW filter 204. The first metal interconnect 230 is configured as a metallized vertical interconnect via (via) 240 extending downward through the cover substrate 220 to the first surface 210 of the first substrate 206 to provide a signal path 232 for the first AW filter circuit 208. Furthermore, at least one second metal interconnect 236 ("metal interconnect 236") in the metallization layer 243 is formed on the outer peripheral wall 244 of the stacked AW filters 202, 204 to provide a signal path 238 for the second AW filter circuit 214 of the second AW filter 204, which is physically and electrically separate from the signal path 232 of the first AW filter 202. Metal interconnect 236 provides a signal path 238 between the second AW filter circuit 214 and contact pads 246 disposed on the contact surface 234 of the cover substrate 220 of the first AW filter 202. Contact pads 246 comprise metal or metal alloy (e.g., solder), which may be formed in pads or bumps and configured to conduct electrical signals. In this example, the metal interconnect 236 formed in the metallization layer 243 is configured to distribute signals from the contact pads 246 to the first surface 210 of the first substrate 206. As a non-limiting example, the metal interconnect 236 may be an RDL interconnect formed in one or more redistribution layers (RDLs) coupled to the contact pads 246, wherein the RDL interconnects are configured to redistribute signals from the contact pads 246 to the first surface 210 of the first substrate 206. The signal path 238 forming the second AW filter 204 in the AW filter package 200, as the second metal interconnect 236 of the metallization layer 243, allows the AW filter package 200 to be manufactured, for example, using a metallization layer manufacturing process. For example, if the metallization layer 243 is an RDL, then an RDL manufacturing process can be used.

[0027] The surfaces on which the metal interconnects 236 can be formed using a metallization layer fabrication process (e.g., an RDL fabrication process) include surfaces parallel to the substrate on a first side (e.g., the upper side), surfaces orthogonal to the substrate (e.g., perpendicular), or surfaces at an angle to the first side of the substrate. However, the metal interconnects 236 may not be successfully formed on angled or horizontal surfaces on a second side (e.g., the lower side) of the substrate and not exposed from a direction orthogonal to the first side of the substrate. For example, the metallization layer can be formed on the upper surface and continuous sidewall surfaces, but not on the lower surface or on sidewall surfaces shielded by the upper substrate. In this regard, in order to successfully fabricate continuous metal interconnects 236 on the outer peripheral walls 244 of the AW filters 202, 204, "negative exposure" areas (such as areas where the upper structure protrudes from the lower structure (e.g., the lower structure is shielded from the first side)) can produce unreliable results in the formation of the metallization layer 243. In an example of a stacked structure, metal interconnects may be formed on the outer peripheral walls of the substrate stack, where the side surfaces of the substrates are aligned in the Z-axis direction. However, this would require that each outer peripheral wall of the stack on which the metal interconnects are located be aligned in the Z-axis direction. In practice, however, manufacturing tolerances of the substrates allow for variations in substrate width and substrate coverage. An upper substrate in the stack has a greater width than a lower substrate in the stack and protrudes beyond the lower substrate on at least one side of the stack, creating a shading region (e.g., a negative exposure region) (e.g., in the Z-axis direction) on a second side of the protruding upper substrate. Such a shading region is not exposed in a direction orthogonal to the first side of the upper substrate (e.g., in the Z-axis direction), and thus the metallization layer may not be properly formed in this shading region.

[0028] In another exemplary embodiment, in an example of a multilayer AW filter package 200, to support the formation of metal interconnects 236 on the outer peripheral walls 244 of stacked AW filters 202 and 204 to provide a signal path 238 to the second AW filter circuit 214, the sidewall surfaces 250 of the cover substrate 220, the sidewall surfaces 252 of the first substrate 206, and the sidewall surfaces 254 of the third substrate 212 may be staggered relative to each other in the horizontal direction. Here, the phrase "staggered" means that the first substrate 206 extends beyond the sidewall surface 250 of the cover substrate 220 in the X-axis direction, and the third substrate 212 extends beyond the sidewall surface 252 of the first substrate 206 in the X-axis direction, such that the sidewall surface 252 of the first substrate 206 lies between the sidewall surface 250 of the cover substrate 220 and the sidewall surface 254 of the third substrate 212 in the X-axis direction. The staggered sidewall surfaces 250, 252 establish a shoulder region 256 of the first substrate 206, which extends outward beyond the sidewall surface 250 of the cover substrate 220 in a direction orthogonal to the sidewall surface 250 of the cover substrate 220 (e.g., in the X-axis direction) (see FIG. 2B). The staggered sidewall surfaces 252, 254 also establish a lower shoulder region 258 on the third substrate 212 in the multilayer AW filter package 200, which extends outward beyond the sidewall surface 252 of the first substrate 206 of the AW filter package 200 (e.g., in the X-axis direction). The shoulder region 256 and the lower shoulder region 258 provide support for forming metal interconnects 236 on the outer peripheral walls 244 of the stacked AW filters 202, 204, for example, using an RDL manufacturing process, and avoid overlap of negative exposure areas where metal interconnects 236 may not be formed.

[0029] Referring further to Figures 2A-2C, a metal interconnect 236 is disposed on the contact surface 234 of the cover substrate 220 and electrically coupled to contact pads 246. The contact pads 246 are configured to couple to external circuitry to receive radio frequency (RF) signals or provide filtered RF signals. Signals received or generated on the contact pads 246 can be electrically coupled via the metal interconnect 236 to one of the second AW filter circuits 214 on the third substrate 212. In this manner, the metal interconnect 236 extends from the contact surface 234 (e.g., the top surface of the AW filter package 200) to the sidewall surface 250 of the cover substrate 220. The sidewall surface 250 of the cover substrate 220 extends vertically (e.g., in the Z-axis direction), orthogonal to the contact surface 234. A first frame 218 is disposed between the cover substrate 220 and the first surface 210 of the first substrate 206. The sidewall surface 260 of the first frame 218 may extend (e.g., in the Z-axis direction) to align with the sidewall surface 250 of the cover substrate 220 without deviating in a direction orthogonal to the sidewall surface 250 of the cover substrate 220 (e.g., the X-axis direction). In this way, the sidewall surface 250 of the cover substrate 220 and the sidewall surface 260 of the first frame 218 may allow the formation of metal interconnects 236 by, for example, an RDL fabrication process or other metallization layer fabrication process. The metal interconnects 236 extend from the sidewall surface 250 of the cover substrate 220 to the sidewall surface 260 of the first frame 218 between the cover substrate 220 and the first substrate 206. The first frame 218 extends from the sidewall surface 250 of the cover substrate 220 on a first side S1 (i.e., inwardly into the first cavity 222) in a direction orthogonal to the sidewall surface 250 of the cover substrate 220 (X-axis direction) to support the cover substrate 220. The first frame 218 comprises a different material than the cover substrate 220. In some examples, the first frame 218 is a polymeric material formed on one of the cover substrate 220 and the first substrate 206 before the cover substrate 220 is stacked on the first substrate 206. For example, the cover substrate 220 may be formed of glass.

[0030] In some examples, the first frame 218 extends on the second side S2 of the sidewall surface 250 of the cover substrate 220 in a direction orthogonal to the sidewall surface 250 of the cover substrate 220 to the shoulder region 256 on the first surface 210 of the first substrate 206. In this manner, the sidewall surface 260 of the first frame 218 is not aligned with the sidewall surface 250 of the cover substrate 220, such that the sidewall surface 260 of the first frame 218 is staggered relative to the sidewall surface 250 of the cover substrate 220, which also allows for the formation of the metal interconnect 236. In such examples, the metal interconnect 236 is also disposed on the top surface 262 of the first frame 218. Therefore, in such examples, the metal interconnect 236 extends from the sidewall surface 250 of the cover substrate 220 to the top surface 262 of the first frame 218 and extends to the sidewall surface 260 of the first frame 218.

[0031] After the metal interconnect 236 is formed along the outer peripheral wall 244 toward the third substrate 212 in the Z-axis direction, the metal interconnect 236 is disposed on the shoulder region 235 of the first substrate 206 and onto the sidewall surface 252 of the first substrate 206. The sidewall surface 252 of the first substrate 206 may be orthogonal to the first surface 210 of the first substrate 206. A second frame 224 is disposed between the first substrate 206 and the third substrate 212. The sidewall surface 264 of the second frame 224 may be aligned with the sidewall surface 252 of the first substrate 206, thereby making it possible to form the metal interconnect 236 extending from the sidewall surface 252 of the first substrate 206 and continuing to the sidewall surface 264 of the second frame 224. The second frame 224 extends from the sidewall surface 252 of the first substrate 206 to the first side S1 (i.e., into the second cavity 226) in a direction orthogonal to the sidewall surface 252 of the first substrate 206 (e.g., the X-axis direction) to support the first substrate 206.

[0032] In some examples, the second frame 224 extends to a second side S2 of the sidewall surface 252 of the first substrate 206 in a direction orthogonal to the sidewall surface 252 of the first substrate 206, thereby interleaving with respect to the sidewall surface 252 of the first substrate 206 (i.e., the sidewall surface 264 of the second frame 224 extends to the side S2 of the sidewall surface 252 of the first substrate 206 in the X-axis direction). In such examples, a metal interconnect 236 is disposed on the top surface 266 of the second frame 224, continues to the sidewall surface 264 of the second frame 224, and is also disposed on the lower shoulder region 258 of the third substrate 212, which is also on the second side S2 of the sidewall surface 264 of the second frame 224.

[0033] To electrically couple the contact pad 246 to the second AW filter circuit 214 on the second surface 216 via the metal interconnect 236, the metal interconnect 236 coupled to the contact pad 246 is also coupled to the surface interconnect 268. The surface interconnect 268 is disposed on the second surface 216 of the third substrate 212 and extends from inside the second cavity 226 to the lower shoulder region 258 (outside the cavity). The surface interconnect 268 is coupled to both the second AW filter circuit 214 and the metal interconnect 236. The second frame 224 is disposed on a portion of the surface interconnect 268 between the second AW filter circuit 214 inside the second cavity 226 and the metal interconnect 236 on the lower shoulder region 254. In this manner, the metal interconnect 236 electrically couples the second AW filter circuit 214 to the contact pad 246.

[0034] In another exemplary configuration, in a multilayer stacked AW filter package 200, a metal interconnect 236 provides a signal path 238 between contact pads 246 and second AW filter circuits 214 on a third substrate 212. The metal interconnect 236 extends across a first substrate 206 including a first AW filter circuit 208. An insulator 270 is disposed on a sidewall surface 252 of the first substrate 206 and between the sidewall surface 252 and the metal interconnect 236. The first substrate 206 includes one of semiconductor substrates 213 having a piezoelectric material 228 on a first surface 210. The piezoelectric material 228 protects the semiconductor substrate 213 (which is a semiconductor) from electrical signals in the metal interconnect 236. During manufacturing, the semiconductor substrate 213 is cut from a wafer, and the sidewall surface 252 of the first substrate 206 is exposed (e.g., unprotected from electrical signals). Therefore, directly disposing the metal interconnect 236 on the sidewall surface 252 of the first substrate 206, in which at least one first AW filter circuit(s) 208 is formed, will result in the first AW filter circuit 208 being electrically coupled to the metal interconnect 236, and thus electrically coupled to the second AW filter circuit 214 and the contact pad 246. As a result of such electrical coupling, current may leak through the semiconductor substrate 213 between the first AW filter circuit 208 and the second AW filter circuit 214, which may interfere with the operation of the first AW filter circuit 208 and the second AW filter circuit 214, and also result in power loss in the AW filter package 200. In this regard, an insulator 270 is disposed on the sidewall surface 252 of the first substrate 206, between the sidewall surface 252 of the first substrate 206 and the metal interconnect 236, to insulate and isolate the first AW filter circuit 208 from the second AW filter circuit 214. In manufacturing, an insulator 270 is disposed on the outer peripheral walls 244 (including the sidewall surface 250 of the cover substrate 220 and the sidewall surface 260 of the first frame 218) of the stacked AW filter 202 and the stacked AW filter 204, and is also disposed on the first surface 210 of the first substrate 206. Subsequently, a metal interconnect 236 is disposed on the insulator 270. Therefore, the insulator 270 is disposed between the sidewall surface 250 of the cover substrate 220 and the metal interconnect 236, between the sidewall surface 260 of the first frame 218 and the metal interconnect 236, and between the first surface 210 of the first substrate 206 and the metal interconnect 236.

[0035] In another embodiment, the first metal interconnect 230 (i.e., via 240) and the second metal interconnect 236 also provide separate thermal paths for distributing heat away from the first and second AW filter circuits 208, 214 to the contact surface 234 of the cover substrate 220 for dissipation from the AW filter package 200. Forming the via 240 in the cover substrate 220 may include, for example, laser drilling in the cover substrate 220 and filling the hole with metal to provide both electrical and thermal conductivity. The via 240 may be formed of copper, aluminum, or other metals or metals that provide both electrical and thermal conductivity.

[0036] In another embodiment, the goal of the multilayer stacked AW filter package 200 is to save area in electronic devices, but area savings are not beneficial unless the increased height obtained is acceptable for use in electronic devices. In this regard, by forming semiconductor substrates 213, the first substrate 206 and the third substrate 212 can be processed by IC processing methods, and the first substrate 206 and the third substrate 212 can be thinned to reduce the package height. Furthermore, the glass cover substrate 220 provides the AW filter package 200 with additional structural integrity that cannot be provided by more flexible cover materials (such as polymers). As an example, the third substrate 212 may have a thickness T 212 in a first direction orthogonal to the second surface 216, ranging from sixty (60) micrometers (µm) to one hundred and thirty (130) micrometers (µm); the first substrate 206 may have a thickness T 206 in the first direction, ranging from thirty (30) µm to seventy (70) µm; and the cover substrate 220 may have a thickness T 220 in the range of thirty (30) µm to seventy (70) µm. In some examples, the thickness T 212 of the third substrate 212 is less than eighty-five (85) µm, the thickness T 206 is less than fifty-five (55) µm, and the thickness T 220 of the cover substrate 220 is less than fifty-five (55) µm.

[0037] The exemplary configuration of the multilayer stacked AW filter package 200 shown in Figures 2A-2C disclosed herein can also be used in the stacked AW filter package 300 shown in Figure 3, which includes: a single AW filter 302 comprising a first substrate 304, an AW filter circuit 306 on a first surface 308 of the first substrate 304, a frame 310 disposed on the first surface 308, and a second substrate 312 disposed (e.g., stacked) on the frame 310. The second substrate 312 is formed by a cover structure, which may also be referred to herein as "cover substrate 312", on the first frame 310. In this regard, a metallization manufacturing process can be used to manufacture a metallization layer 313 including at least one metal interconnect 314 ("metal interconnect 314"). As a non-limiting example, the metallization layer 312 may be an RDL having RDL interconnects therein, thereby providing a signal path 316 for the AW filter 302 even in the AW filter package 300 which does not include the stacked AW filter. Metal interconnect 314 provides a signal path 316 (and a thermal path) from the first substrate 304 to the contact pads 318 on the contact surface 320 of the cover substrate 312. Metal interconnect 314 is disposed on the contact surface 320 and electrically coupled to the contact pads 318, and also coupled to the first surface 308 of the first substrate 304.

[0038] To employ a metallization manufacturing process, such as the RDL manufacturing method as a non-limiting example, the sidewall surface 322 of the first substrate 304 is staggered relative to the sidewall surface 324 of the cover substrate 312, as discussed above in the multilayer AW filter package 200. Therefore, the first surface 308 includes a shoulder region 326 extending in a direction orthogonal to the sidewall surface 324 of the cover substrate 312. Metal interconnects 314 extend onto the sidewall surface 324 of the cover substrate 312. In an example where the sidewall surface 328 of the frame 310 is aligned with the sidewall surface 324 of the cover substrate 312 (e.g., along the Y-axis), the metal interconnects 314 extend from the sidewall surface 324 of the cover substrate 312 to the sidewall surface 328 of the frame 310. The frame 310 extends from the sidewall surface 324 of the cover substrate 312 to a first side S1 between the cover substrate 312 and the first substrate 304 to support the cover substrate 312 and provide a cavity 330. In some examples, the frame 310 is not aligned with the sidewall surface 324 of the cover substrate 312. Alternatively, the frame 310 extends beyond the sidewall surface 324 of the cover substrate 312 in a direction orthogonal to it, reaching a second side S2 of the sidewall surface 324 to the shoulder region 326 of the first substrate 304, such that the sidewall surface 328 on the frame 310 is staggered relative to the sidewall surface 324 of the cover substrate 312. In this example, a metal interconnect 314 extends from the sidewall surface 324 of the cover substrate 312 to the top surface 332 of the frame 310 and to the sidewall surface 328 of the frame 310. The metal interconnect 314 is disposed on a first surface 308 of the first substrate 304. Surface interconnects 334 disposed on the first surface 308 extend from within the cavity 330, wherein the surface interconnects 334 are electrically coupled to the AW filter circuit 306, pass through the frame 310, and enter the shoulder region 326. Metal interconnects 314 are electrically coupled to the surface interconnects 334 in the shoulder region 326 to electrically couple the AW filter circuit 306 to the contact pads 318.

[0039] Figure 4 is a flowchart of process 400 for manufacturing the stacked AW filter package 300. Process 400 includes forming a first substrate 304 (block 402) including a first surface 308, and forming an AW filter circuit 306 (block 404) on the first surface 308 of the first substrate 304. Process 400 includes forming a frame 310 (block 406) on the first surface 308 of the first substrate 304, and forming a second substrate (e.g., a cover substrate) 312 (block 408) including a contact surface 320 and a sidewall surface 324. The procedure 400 includes disposing a cover substrate 312 on a frame 310 to form a cavity 330 (block 410) between the AW filter circuit 306 and the cover substrate 312, and forming a metallization layer 313 including at least one metal interconnect 314 coupled to a contact surface 320 of the cover substrate 312 and a first surface 308 of the first substrate 304, the at least one metal interconnect 314 being disposed on a sidewall surface 324 (block 412) of the cover substrate 312.

[0040] Figures 5A and 5B are flowcharts of a process 500 for manufacturing a stacked AW filter package 200. Process 500 includes forming a first substrate 206 (block 502) including a first surface 210 and a sidewall surface 252, and forming a first AW filter circuit 208 (block 504) on the first surface 210 of the first substrate 206. Process 500 includes forming a first frame 218 (block 506) on the first surface 210 of the first substrate 206, and forming a cover substrate 220 (block 508) including a contact surface 234 and a sidewall surface 250. Process 500 includes disposing the cover substrate 220 on the first frame 218 to form a first cavity 222 (block 510) between the first AW filter circuit 208 and the cover substrate 220, and forming a third substrate 212, the third substrate 212 including a second AW filter circuit 214 (block 512) on its second surface 216. The process 500 includes forming a second frame 224 (block 514) on the second surface 216 of the third substrate 212 and disposing a first substrate 206 on the second frame 224 to form a second cavity 226 (block 516) between the second AW filter circuit 214 and the first substrate 206. The process 500 includes forming an insulator 268 (block 518) on the sidewall surface 256 of the first substrate 206 and forming a metallization layer 243 including a contact surface 234 coupled to the cover substrate 220 and at least one metal interconnect 236 on the second surface 216 of the third substrate 212, the at least one metal interconnect 236 being disposed on an insulator 270 on the sidewall surface 252 of the first substrate 206 (block 520).

[0041] Figure 6 is an illustration of a top view of an example of a frame 600 supporting the fabrication of stacked AW filter packages 200 and 300. Frame 600 may correspond to frames 218 and 224 in Figures 2A-2C and frame 310 in Figure 3. Frame 600 includes a perimeter frame 602 extending along the perimeter 604 of a first substrate 606, which is larger in the X and Y directions, such that the first substrate 606 includes shoulder regions 608 staggered in width relative to frame 600. In some examples, the frame 600 may be the same size as or slightly larger than a second substrate (e.g., a cover substrate) to avoid "negative exposure" areas where metal interconnects cannot be formed. The perimeter frame 602 in this example is rectangular, but may also be square or other shapes corresponding to the perimeter of the second substrate to be supported. Frame 600 includes frame member 610, which supports the second substrate against pressure on the contact surface by providing additional support, thereby increasing the size of cavity 612 to include more AW filter circuitry 614 on the first substrate 606. Frame member 610 extends from perimeter frame 620 across cavity 612. Frame member 610 may be linear, having a first end 616 that contacts and extends from perimeter frame 602. Frame member 610 is included in the cavity and does not contact a second end 618 of perimeter frame 602. Cavity 612 continues (i.e., uninterruptedly) around the second end 618 from a first cavity portion 620A on the first side of frame member 610 to a second cavity portion 620B on the second side of frame member 610. AW filter circuitry 614 may be disposed in the first cavity portion 620A. In some examples, another AW filter circuitry 624 may be disposed in the second cavity portion 620B. As shown, the frame 600 includes a plurality of frame members 610 extending from the perimeter frame 602 into the cavity 612 to support the second substrate.

[0042] Perimeter frame 602 and frame member 610 contact the second substrate (not shown) and the first substrate 606. Frame member 610 supports the stacked AW filter package by providing additional support within cavity 612 to resist pressure on the contact surfaces of the first substrate. Pressure applied to the first substrate (which may be a glass substrate) causes the glass, as well as the top substrate in the stacked AW filter package, to deflect inward. In areas of cavity 612 where frame member 610 is not present (i.e., without frame member 610), if such unsupported areas are too large, the glass may deflect under pressure to the point of breakage. However, due to the structural rigidity of the second glass substrate, the cavity 612 of the AW filter package as disclosed herein may include a circular region 626 having a diameter of up to 400 µm, excluding perimeter frame 602 and frame member 610. In some examples, the circular region 626 has a diameter (D1) ranging from 360 µm to 400 µm.

[0043] Figure 7 is a top perspective view of a stacked AW filter package 700. The stacked AW filter package 700 includes a second substrate 702 stacked above a first substrate 704 to form a first AW filter 706. The second substrate 702 has a cover structure, also referred to herein as a "cover substrate 702," formed by being disposed above the first frame 704. The first AW filter 706 also provides a cover structure stacked on a third substrate 708 to form a second AW filter 710. The stacked AW filter package 700 includes contact pads 712 on the cover substrate 702. The contact pads 712 are coupled to a first metal interconnect 714, which includes vias 716 extending through the cover substrate 702 to couple to a first AW filter circuit (not shown) on the first substrate 704. A second metal interconnect 718 (which may be an RDL interconnect) extends along an outer peripheral wall 720 from the contact pads 712 to the second AW filter 710. The second metal interconnect 718 is disposed on an insulator 722 on the sidewall surface 724 of the first substrate 704 to couple the contact pad 712 to the second AW filter circuit (not shown) on the third substrate 708 without electrically coupling to the semiconductor material of the first substrate 704.

[0044] Figure 8 illustrates an exemplary wireless communication device 800 comprising RF components formed of one or more ICs 802 and including a stacked AW filter package 803. The stacked AW filter package 803 includes: a first AW filter circuit disposed on a first substrate, a second substrate disposed on a first frame disposed on the first substrate, and a first substrate disposed on a second frame disposed on a third substrate to surround a second bottom AW filter circuit, wherein contact pads on the second substrate are electrically coupled to the second AW filter circuit by metal interconnects disposed on an insulator to prevent leakage current from reaching the first substrate, as illustrated in Figures 2A-2C, 3, and 7 and according to any of the embodiments disclosed herein. As an example, the wireless communication device 800 may be included in or provided in any of the above-described devices. As shown in Figure 8, the wireless communication device 800 includes a transceiver 804 and a data processor 806. The data processor 806 may include memory for storing data and code. The transceiver 804 includes a transmitter 808 and a receiver 810 supporting bidirectional communication. Generally, wireless communication device 800 may include any number of transmitters 808 and / or receivers 810 for any number of communication systems and frequency bands. All or part of transceiver 804 may be implemented on one or more analog ICs, RF ICs, mixed-signal ICs, etc.

[0045] Transmitter 808 or receiver 810 can be implemented using a superheterodyne architecture or a direct conversion architecture. In a superheterodyne architecture, the signal is converted in multiple stages between the RF and baseband frequencies; for example, from RF to intermediate frequency (IF) in one stage and then from IF to baseband in another stage. In a direct conversion architecture, the signal is converted between the RF and baseband frequencies in one stage. Superheterodyne and direct conversion architectures can use different circuit blocks and / or have different requirements. In the wireless communication device 800 in Figure 8, transmitter 808 and receiver 810 are implemented using a direct conversion architecture.

[0046] In the transmission path, data processor 806 processes the data to be transmitted and provides I and Q analog output signals to transmitter 808. In the exemplary wireless communication device 800, data processor 806 includes digital-to-analog converters (DACs) 812(1), 812(2) to convert digital signals generated by data processor 806 into I and Q analog output signals (e.g., I and Q output currents) for further processing.

[0047] Within transmitter 808, low-pass filters 814(1) and 814(2) filter the I and Q analog output signals, respectively, to remove unwanted signals caused by the preceding digital-to-analog conversion. Low-pass filters 814(1) and 814(2) can be implemented as an AW filter package 803. Amplifiers (AMPs) 816(1) and 816(2) amplify the signals from low-pass filters 814(1) and 814(2), respectively, and provide I and Q baseband signals. Upconverter 818 upconverts the I and Q baseband signals from transmit (TX) local oscillator (LO) signal generator 820 using mixers 822(1) and 820(2) to provide upconverted signal 824. Filter 826 filters upconverted signal 824 to remove unwanted signals caused by upconversion and noise in the receive band. Power amplifier (PA) 828 amplifies the up-converted signal 826 from filter 824 to obtain the desired output power level and provide a transmitted RF signal. This transmitted RF signal is routed through duplexer or switch 830 and transmitted via antenna 832. Either low-pass filters 814(1) and 814(2) or filter 826 may be an acoustic wave filter (AW filter) package 803.

[0048] In the receiving path, antenna 832 receives the signal transmitted by the base station and provides a received RF signal, which is routed through duplexer or switch 830 and provided to low-noise amplifier (LNA) 834. Duplexer or switch 830 is designed to operate with a specific receive (RX) and TX duplexer frequency separation, such that the RX signal is isolated from the TX signal. The received RF signal is amplified by LNA 834 and filtered by filter 836 to obtain the desired RF input signal. Down-conversion mixers 838(1) and 838(2) mix the output of filter 836 with the I and Q RX LO signals (i.e., LO_I and LO_Q) from RX LO signal generator 840 to generate I and Q baseband signals. The I and Q fundamental frequency signals are amplified by AMPs 842(1) and 842(2) and further filtered by low-pass filters 844(1) and 844(2) to obtain I and Q analog input signals, which are provided to data processor 806. Either filter 836 and low-pass filters 844(1) and 844(2) can be an AW filter package 803. In this example, data processor 806 includes analog-to-digital converters (ADCs) 846(1) and 846(2) to convert the analog input signals into digital signals to be further processed by data processor 806.

[0049] In the wireless communication device 800 of Figure 8, a TX LO signal generator 822 generates I and Q TX LO signals for up-conversion, while an RX LO signal generator 840 generates I and Q RX LO signals for down-conversion. Each LO signal is a periodic signal with a specific base frequency. A TX phase-locked loop (PLL) circuit 848 receives timing information from a data processor 806 and generates control signals for adjusting the frequency and / or phase of the TX LO signals from the TX LO signal generator 822. Similarly, an RX PLL circuit 850 receives timing information from a data processor 806 and generates control signals for adjusting the frequency and / or phase of the RX LO signals from the RX LO signal generator 840.

[0050] Each of the wireless communication devices 800, which may include a stacked AW filter package 803, may be provided in or integrated into any processor-based device. The stacked AW filter package 803 includes a second substrate stacked on a first substrate, the first substrate including a first AW filter circuit, the first substrate being further stacked on a third substrate including a second AW filter circuit, wherein contact pads on the second substrate are electrically coupled to the second AW filter circuit by metal interconnects disposed on an insulator to protect against leakage current reaching the first substrate, as illustrated in Figures 2A-2C, 3 and 7 and according to any of the configurations disclosed herein. Examples not limited to these include: set-top boxes, entertainment units, navigation devices, communication devices, fixed location data units, mobile location data units, Global Positioning System (GPS) devices, mobile phones, cellular phones, smartphones, SIP phones, tablet devices, tablet phones, servers, computers, portable computers, mobile computing devices, wearable computing devices (e.g., smartwatches, health or fitness trackers, glasses, etc.), desktop computers, personal digital assistants (PDAs), monitors, computer monitors, televisions, tuners, radios, satellite radios, music players, digital music players, portable music players, digital video players, video players, digital video disc (DVD) players, portable digital video players, automobiles, vehicle components, avionics systems, drones, and multi-rotor aircraft.

[0051] Figure 9 illustrates an example of a processor-based system 900 including RF circuitry comprising a stacked AW filter package 901. The stacked AW filter package 901 includes: a first AW filter circuit disposed on a first substrate; a second substrate disposed on a first frame disposed on the first substrate; and a first substrate disposed on a second frame disposed on a third substrate to surround a second bottom AW filter circuit, wherein contact pads on the second substrate are electrically coupled to the second AW filter circuit via metal interconnects disposed on an insulator to protect against leakage current reaching the first substrate, as illustrated in Figures 2A-2C, 3, and 7, and according to any configuration disclosed herein. In this example, the processor-based system 900 includes one or more central processing units (CPUs) 902, which may also be referred to as CPUs or processor cores, each CPU 902 including one or more processors 904. The CPU 902 may have cache memory 906 coupled to the processors 904 for fast access to temporarily stored data. CPUs 902 are coupled to system buses 908 and are interactively coupled to master and slave devices included in the processor-based system 900. As is well known, CPUs 902 communicate with these other devices by exchanging address, control, and data information on system buses 908. For example, CPUs 902 may communicate bus transaction requests to memory controllers 910, which is an example of a slave device. Although not illustrated in Figure 9, multiple system buses 908 may be provided, each forming a different texture.

[0052] Other master and slave devices may be connected to system bus 908. As illustrated in FIG9, these devices may, as an example, include a memory system 912 comprising a memory controller 910 and one or more memory arrays 914, one or more input devices 916, one or more output devices 918, one or more network peripheral devices 920, and one or more display controllers 922. Each of the memory system 912, the one or more input devices 916, the one or more output devices 918, the one or more network peripheral devices 920, and the one or more display controllers 922 may include RF circuitry comprising a stacked AW filter package 901. The stacked AW filter package 901 includes: a first AW filter circuit disposed on a first substrate, a second substrate disposed on a first frame disposed on the first substrate, and a first substrate disposed on a second frame disposed on a third substrate to surround a second bottom AW filter circuit, wherein contact pads on the second substrate are electrically coupled to the second AW filter circuit by metal interconnects disposed on an insulator to protect against leakage current reaching the first substrate, as illustrated in Figures 2A-2C, 3, and 7 and according to any configuration disclosed herein. Input devices 916 may include any type of input device, including but not limited to input keys, switches, voice processors, etc. Output devices 918 may include any type of output device, including but not limited to audio, video, other visual indicators, etc. Network peripheral devices 920 may be any device configured to allow data exchange to and from the network 924. Network 924 can be any type of network, including but not limited to wired or wireless networks, private or public networks, local area networks (LANs), wireless local area networks (WLANs), wide area networks (WANs), Bluetooth™ networks, and the Internet. Network peripheral devices 920 can be configured to support any type of communication protocol desired.

[0053] CPU 902 may also be configured to access display controller 922 on system bus 908 to control information sent to one or more displays 926. Display controller 922 sends information to be displayed to displays 926 via one or more video processors 928, which process the information to be displayed into a format suitable for displays 926. Displays 926 may include any type of display, including but not limited to cathode ray tube (CRT), liquid crystal display (LCD), plasma display, light-emitting diode (LED) display, etc. Display controller 922, displays 926 and / or video processors 928 may include RF circuitry including a stacked AW filter package 901. The stacked AW filter package 901 includes: a first AW filter circuit disposed on a first substrate, a second substrate disposed on a first frame disposed on the first substrate, and a first substrate disposed on a second frame disposed on a third substrate to surround a second bottom AW filter circuit, wherein contact pads on the second substrate are electrically coupled to the second AW filter circuit by metal interconnects disposed on an insulator to protect against leakage current reaching the first substrate, as illustrated in Figures 2A-2C, 3 and 7 and according to any of the embodiments disclosed herein.

[0054] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithms described herein can be implemented as electronic hardware, stored in memory or another computer-readable medium and executed by a processor or other processing device, or a combination of both. As an example, the master and slave devices described herein can be used in any circuit, hardware component, IC, or IC chip. The memory disclosed herein can be of any type and size and can be configured to store any type of information desired. To clearly illustrate this interchangeability, various illustrative elements, blocks, modules, circuits, and steps have been generally described above in their functional form. How such functionality is implemented depends on the specific application, design choices, and / or design constraints imposed on the overall system. Those skilled in the art can implement the described functionality in different ways for each specific application, but such implementation decisions should not be construed as departing from the scope of this document.

[0055] The various illustrative logic blocks, modules, and circuits described herein can be implemented or executed using processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, individual gate or transistor logic, individual hardware components, or any combination thereof, designed to perform the functions described herein. The processor may be a microprocessor, but in alternatives, it may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors coordinated with a DSP core, or any other such configuration).

[0056] The various forms disclosed herein can be embodied in hardware and instructions stored in the hardware, and can reside in, for example, random access memory (RAM), flash memory, read-only memory (ROM), electrically programmable ROM (EPROM), electronically erasable programmable ROM (EEPROM), registers, hard disks, removable disks, CD-ROMs, or any other form of computer-readable media known in the art. Exemplary storage media are coupled to a processor so that the processor can read and write information to / from the storage media. In alternatives, the storage media can be integrated into the processor. The processor and storage media can reside in an ASIC. The ASIC can reside in a remote station. In alternatives, the processor and storage media can reside as separate components in a remote station, base station, or server.

[0057] It should also be noted that the operational steps described in any of the exemplary samples herein are described for the purpose of providing examples and discussion. The described operations may be performed in many different orders other than those stated. Furthermore, the operations described in a single operational step may actually be performed in multiple different steps. Additionally, one or more operational steps discussed in the exemplary samples may be combined. It should be understood that, as will be apparent to those skilled in the art, many different modifications may be made to the operational steps illustrated in the flowcharts. Those skilled in the art will also understand that information and signals can be represented using any of a variety of different techniques and skills. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, or any combination thereof.

[0058] The prior description of this invention is provided to enable anyone skilled in the art to make or use it. Various modifications to this invention will be apparent to those skilled in the art, and the universal principles defined herein can be applied to other variations. Therefore, this invention is not intended to be limited to the examples and designs described herein, but should be granted the broadest scope consistent with the principles and novel features revealed herein.

[0059] Examples of implementations are described in the following numbered clauses. 1. A stacked acoustic wave (AW) filter package, comprising: A first substrate including a first surface; The AW filter circuit on the first surface of the first substrate; A frame disposed on the first surface of the first substrate; A second substrate, including a contact surface and a sidewall surface, is disposed on the frame to form a cavity between the AW filter circuit and the second substrate; and The metallization layer includes at least one metal interconnect coupled to the contact surface of the second substrate and the first surface of the first substrate, the at least one metal interconnect being disposed on the sidewall surface of the second substrate. 2. The stacked AW filter package as described in Clause 1 further includes contact pads coupled to the contact surface; The at least one metal interconnect is configured to redistribute signals from the contact pad to the first surface of the first substrate. 3. A stacked AW filter package as described in Clause 1 or Clause 2, wherein: The frame is disposed between the second substrate and the first surface of the first substrate, and extends from the sidewall surface of the second substrate on a first side of the sidewall surface of the second substrate in a direction orthogonal to the sidewall surface of the second substrate; and The first surface of the first substrate includes a shoulder region on a second side of the sidewall surface of the second substrate in a direction orthogonal to the sidewall surface of the second substrate. 4. As in Clause 3, a stacked AW filter package, wherein: The at least one metal interconnect is disposed on the shoulder region of the first surface of the first substrate. 5. The stacked AW filter package of any of the terms 1-4 further includes contact pads on the contact surface, the contact pads being configured to be coupled to external circuitry, wherein the at least one metal interconnect is electrically coupled to the contact pads. 6. The stacked AW filter package of any of 2-5 further includes a surface interconnect extending from the interior of the cavity to the shoulder region on the first surface of the first substrate, the surface interconnect being electrically coupled to the AW filter circuit and the at least one metal interconnect of the metallization layer on the shoulder region. 7. A stacked AW filter package as described in any of Clauses 1-6, wherein at least one metal interconnect of the metallization layer is disposed on the side surface of the frame between the second substrate and the first substrate. 8. A stacked AW filter package as described in any of Clauses 2-7, wherein: The frame extends into the shoulder region on the second side of the sidewall surface of the second substrate in a direction orthogonal to the sidewall surface of the second substrate; and The at least one metal interconnect of the metallization layer is disposed on the top surface of the frame. 9. A stacked AW filter package as described in any of Clauses 1-8, wherein the frame comprises a first material and the second substrate comprises a second material different from the first material. 10. A stacked AW filter package as described in any of clauses 1-9, wherein: The framework comprises polymer materials; The second substrate includes glass; and The first substrate includes semiconductor material. 11. A stacked AW filter package as described in any of clauses 1-10, wherein: The frame further includes a perimeter frame disposed along the perimeter of the second substrate; and The cavity is surrounded by the perimeter frame. 12. The stacked AW filter package of Clause 11, wherein the frame further includes a frame member extending into the cavity and orthogonal to at least a portion of the perimeter frame. 13. The stacked AW filter package as described in Clause 12, wherein the frame member comprises one of a plurality of frame members of the frame. 14. As in Clause 12 or Clause 13, the stacked AW filter package further includes a linear frame member including a first end coupled to the perimeter frame. 15. The stacked AW filter package of Clause 14, wherein the cavity includes a continuous cavity extending from a first cavity portion on a first side of the linear frame member and around a second end of the linear frame member to a second cavity portion on a second side of the linear frame member. 16. The stacked AW filter package as described in Clause 15, wherein: The AW filter circuit on the first surface of the first substrate is a first AW filter circuit; The first AW filter circuit is disposed within the first cavity portion on the first side of the linear frame member; and The stacked AW filter package further includes another AW filter circuit on the second side of the linear frame member. 17. A stacked AW filter package as described in any of Clauses 1-16, wherein the cavity includes a continuous circular region having a diameter of up to 400 micrometers (µm) excluding the frame therefrom. 18. A stacked AW filter package as described in any of Clauses 1-17, wherein the diameter of the continuous circular region is greater than 360 µm. 19. The stacked AW filter package as described in Clause 5, further comprising: A third substrate, the third substrate including a second AW filter circuit on a second surface of the third substrate; and A second frame disposed on the second surface of the third substrate; in: The first substrate is disposed on the second frame to form a second cavity between the second AW filter circuit and the first substrate. 20. The stacked AW filter package as described in Clause 19, wherein: The first substrate further includes a sidewall surface orthogonal to the first surface of the first substrate; The second frame is disposed between the second surfaces of the first substrate and the third substrate, and extends from the sidewall surface of the first substrate on a first side of the sidewall surface in a direction orthogonal to the sidewall surface of the first substrate; The second surface of the third substrate includes a lower shoulder region on the second side of the sidewall surface of the first substrate in a direction orthogonal to the first sidewall surface of the first substrate. 21. The stacked AW filter package as described in Clause 20, wherein: The at least one metal interconnect is provided in: On the sidewall surface of the first substrate; and On the lower shoulder region of the second surface of the third substrate. 22. The stacked AW filter package of Clause 21 further includes a surface interconnect on the second surface of the third substrate, extending from the interior of the second cavity to the lower shoulder region, the surface interconnect being electrically coupled to the second AW filter circuit and the at least one metal interconnect on the lower shoulder region. 23. A stacked AW filter package as described in any of clauses 19-22, wherein the at least one metal interconnect is disposed on the side surface of the second frame between the first substrate and the third substrate. 24. A stacked AW filter package as described in any of clauses 20-23, wherein: The second frame extends in a direction orthogonal to the sidewall surface of the first substrate to the lower shoulder region on the second side of the sidewall surface of the first substrate; and The at least one metal interconnect is disposed on the top surface of the second frame. 25. A method for manufacturing a stacked acoustic wave (AW) filter package, the method comprising: A first substrate including a first surface is formed; An AW filter circuit is formed on the first surface of the first substrate; A frame is formed on the first surface of the first substrate; A second substrate is formed, comprising a contact surface and a sidewall surface; The second substrate is disposed on the frame to form a cavity between the AW filter circuit and the second substrate; and A metallization layer is formed comprising at least one metal interconnect coupled to the contact surface of the second substrate and the first surface of the first substrate, the at least one metal interconnect being disposed on the sidewall surface of the second substrate. 26. The method as described in Clause 25 further includes: The frame is disposed between the first surface of the second substrate and the first substrate, and extends from the sidewall surface of the second substrate on a first side of the sidewall surface in a direction orthogonal to the sidewall surface of the second substrate; and A shoulder region of the first surface of the first substrate is formed on a second side of the sidewall surface of the second substrate in a direction orthogonal to the sidewall surface of the second substrate. 27. A stacked acoustic wave (AW) filter package, comprising: A first substrate including a first surface and sidewall surfaces; A first AW filter circuit on the first surface of the first substrate; A first frame disposed on the first surface of the first substrate; A second substrate, including a contact surface and a sidewall surface, is disposed on the first frame to form a first cavity between the first AW filter circuit and the second substrate; A third substrate, wherein a second AW filter circuit is included on the second surface of the third substrate; A second frame disposed on the second surface of the third substrate; The first substrate is disposed on the second frame to form a second cavity between the second AW filter circuit and the first substrate; A metallization layer comprising at least one metal interconnect coupled to the contact surface of the second substrate and the second surface of the third substrate, the at least one metal interconnect being disposed on the sidewall surface of the first substrate; and An insulator disposed on the sidewall surface of the first substrate and between the sidewall surface of the first substrate and the at least one metal interconnect. 28. A stacked AW filter package as described in Clause 27, wherein the insulator is disposed between the at least one metal interconnect and the first frame. 29. A stacked AW filter package as described in Clause 27 or Clause 28, wherein the insulator is disposed between the at least one metal interconnect and the first surface of the first substrate. 30. A stacked AW filter package as described in any of clauses 27-29, wherein the insulator is disposed between the at least one metal interconnect and the sidewall surface of the second substrate. 31. The stacked AW filter package of any of the terms 27-30 further includes a through-hole extending from the contact surface through the second substrate to the first surface of the first substrate. 32. The stacked AW filter package of Clause 31 further includes contact pads on the contact surface, wherein: The contact pad is configured to conduct electrical signals; and The via is configured to electrically couple the first AW circuit to the contact pad. 33. A stacked AW filter package as described in any of clauses 27-32, wherein: The thickness of the third substrate in a first direction orthogonal to the second surface is in the range of 60 to 130 micrometers (µm); The thickness of the first substrate in the first direction is in the range of 30 to 70 µm; and The thickness of the second substrate in the first direction is in the range of 30 to 70 µm. 34. A stacked AW filter package as described in any of clauses 27-33, wherein: The thickness of the first substrate is less than 85 µm; The thickness of the third substrate is less than 55 µm; and The thickness of the second substrate is less than 55 µm. 35. A method for forming a stacked acoustic wave filter (AW filter) package, comprising: A first substrate is formed, comprising a first surface and sidewall surfaces; A first AW filter circuit is formed on the first surface of the first substrate; A first frame is formed on the first surface of the first substrate; A second substrate is formed, comprising a contact surface and a sidewall surface; The second substrate is disposed on the first frame to form a first cavity between the first AW filter circuit and the second substrate; A third substrate is formed, wherein a second AW filter circuit is included on the second surface of the third substrate; A second frame is formed on the second surface of the third substrate; The first substrate is disposed on the second frame to form a second cavity between the second AW filter circuit and the first substrate; An insulator is formed on the sidewall surface of the first substrate; and A metallization layer is formed comprising at least one metal interconnect coupled to the contact surface of the second substrate and the second surface of the third substrate, the at least one metal interconnect being disposed on the insulator on the sidewall surface of the first substrate.

[0060] 21:Substrate 21,22:Substrate 21~22:Substrate 100: Surface Acoustic Wave (SAW) Filter Circuit 102: First substrate 104:AW filter 106: Piezoelectric materials 108: First Surface 110(1): First interdigital transducer (IDT) 110(2): Second IDT 112: Input RF signal 114A: First metal interconnect 114B: First metal interconnect 116A: First metal contact 116B: First metal contact 118A: Interdigitated metal interconnect 118B: Interdigitated Metal Interconnect 122A: Interdigitated metal interconnect 122B: Interdigitated metal interconnect 124A: Second metal contact 124B: Second metal contact 126A: Second metal interconnect 126B: Second metal interconnect 120: Filtered RF signal 200:AW filter package 202: First AW Filter 204: Second AW filter 206: First substrate 208: First AW filter circuit 210: First Surface 212: Third substrate 213: Semiconductor substrate 214: Second AW filter circuit 216: Second Surface 218: First Framework 220: Cover substrate 222: First Cavity 224: Second Frame 226: Second Chamber 228: Piezoelectric materials 230: First metal interconnect 232: Interconnection Path 234: Contact surface 236: Metal interconnect 238: Signal Path 240: Through hole 243: Metallization layer 244: Peripheral wall 246: Contact pad 250: Sidewall surface 252: Sidewall surface 254: Sidewall surface 256: Shoulder area 258: Lower shoulder area 260: Sidewall surface 262: Top surface 264: Sidewall Surface 266: Top surface 268: Surface Interconnect 270: Insulator 300: Stacked AW filter package 302: Single AW filter 304: First substrate 306:AW filter circuit 308: First Surface 310: Framework 312: Second substrate 314: Metal interconnect 316: Signal Path 318: Contact pad 320: Contact surface 322: Sidewall surface 324: Sidewall surface 326: Shoulder area 328: Sidewall surface 330: cavity 332: Top surface 334: Surface Interconnect 400: Program 402: Square 404: Square 406: Square 408: Square 410: Square 412: Square 500: Program 502: Square 504: Square 506: Square 508: Square 510: Square 512: Square 514: Square 516: Square 518: Square 520: Square 600: Frame 602: Perimeter Frame 604: Perimeter 606: First substrate 608: Shoulder area 610: Frame components 612: cavity 614: AW Filter Circuit 616: First end 618: Second End 624: Another AW filter circuit 626: Circular area 700: Stacked AW Filter Package 702: Second substrate 704: First Frame 706: First AW Filter 708: Third substrate 710: Second AW filter 712: Contact pad 714: First Metal Interconnect 716: Through hole 718: Second Metal Interconnect 720: Peripheral wall 722: Insulator 724: Sidewall Surface 800: Exemplary Wireless Communication Device 802:IC 803: Stacked AW Filter Package 804: Transceiver 806: Data Processor 808: Transmitter 810: Receiver 818: Upconverter 822: Mixer 824: Up-converted signal 826: Filter 828: Power Amplifier (PA) 830: Duplexer or switch 832: Antenna 834: Low-noise amplifier (LNA) 836: Filter 840:RX LO signal generator 848: TX Phase-Locked Loop (PLL) Circuit 850:RX PLL circuit 900: System 901: Stacked AW Filter Package 902: Central Processing Unit (CPU) 904: Processor 906: Cache memory 908: System Bus 910: Memory Controller 912: Memory System 914: Memory Array 916: Input device 918: Output device 920: Network peripheral equipment 922: Display Controller 924: Internet 926: Monitor 928: Video Processor 620A: First cavity section 620B: Second cavity section 812(1): Digital-to-Analog Converter (DAC) 812(2): Digital-to-Analog Converter (DAC) 814(1): Low-pass filter 814(2): Low-pass filter 816(1): Amplifier (AMP) 816(2): Amplifier (AMP) 820(1): Mixer 820(2): Mixer 838(1): Down-conversion mixer 838(2): Down-conversion mixer 842(1):AMP 842(2):AMP 844(1): Low-pass filter 844(2): Low-pass filter 846(1): Analog-to-Digital Converter (ADC) 846(2): Analog-to-Digital Converter (ADC) D1: Diameter T 206: Thickness T 212: Thickness T 220: Thickness X: axis Y: axis Z: Axis

[0061] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A stacked acoustic wave (AW) filter package, comprising: The system comprises: a first substrate having a first surface; an AW filter circuit on the first surface of the first substrate; a frame disposed on the first surface of the first substrate; a second substrate having a contact surface and a sidewall surface, the second substrate being disposed on the frame to form a cavity between the AW filter circuit and the second substrate; and a metallization layer having at least one metal interconnect coupled to the contact surface of the second substrate and the first surface of the first substrate, the at least one metal interconnect being disposed on the sidewall surface of the second substrate; wherein the frame further comprises a perimeter frame disposed along a perimeter of the second substrate, and a frame member extending into the cavity and orthogonal to at least a portion of the perimeter frame; and wherein the cavity is surrounded by the perimeter frame.

2. The stacked AW filter package of claim 1 further includes a contact pad coupled to the contact surface; the at least one metal interconnect is configured to redistribute a signal from the contact pad to the first surface of the first substrate.

3. As in request item 1, the stacked AW filter package, wherein: The frame is disposed between the second substrate and the first surface of the first substrate, extending from the sidewall surface of the second substrate on a first side of the sidewall surface of the second substrate in a direction orthogonal to the sidewall surface of the second substrate; and the first surface of the first substrate includes a shoulder region on a second side of the sidewall surface of the second substrate in a direction orthogonal to the sidewall surface of the second substrate.

4. As in request item 3, the stacked AW filter package, wherein: The at least one metal interconnect is disposed on the shoulder region of the first surface of the first substrate.

5. The stacked AW filter package of claim 4 further includes a contact pad on the contact surface, the contact pad being configured to be coupled to an external circuit, wherein the at least one metal interconnect is electrically coupled to the contact pad.

6. The stacked AW filter package of claim 4 further includes a surface interconnect extending from the interior of the cavity to the shoulder region on the first surface of the first substrate, the surface interconnect being electrically coupled to the AW filter circuit and the at least one metal interconnect of the metallization layer on the shoulder region.

7. The stacked AW filter package of claim 6, wherein the at least one metal interconnect of the metallization layer is disposed on one side surface of the frame between the second substrate and the first substrate.

8. As in request item 7, a stacked AW filter package, wherein: The frame extends into the shoulder region on the second side of the sidewall surface of the second substrate in a direction orthogonal to the sidewall surface of the second substrate; and at least one metal interconnect of the metallization layer is disposed on a top surface of the frame.

9. The stacked AW filter package of claim 1, wherein the frame includes a first material and the second substrate includes a second material different from the first material.

10. As in request item 9, a stacked AW filter package, wherein: The frame includes a polymer material; the second substrate includes a glass; and the first substrate includes a semiconductor material.

11. The stacked AW filter package of claim 1, wherein the frame component includes one of a plurality of frame components of the frame.

12. As in the stacked AW filter package of claim 1, the frame component further includes a linear frame component including a first end coupled to the perimeter frame.

13. The stacked AW filter package of claim 12, wherein the cavity includes a continuous cavity extending from a first cavity portion on a first side of the linear frame member and around a second end of the linear frame member to a second cavity portion on a second side of the linear frame member.

14. As in request item 13, a stacked AW filter package, wherein: The AW filter circuit on the first surface of the first substrate is a first AW filter circuit; the first AW filter circuit is disposed in the first cavity portion on the first side of the linear frame member; and the stacked AW filter package further includes another AW filter circuit on the second side of the linear frame member.

15. The stacked AW filter package of claim 1, wherein the cavity includes a continuous circular region having a diameter of up to 400 micrometers (µm) excluding the frame therefrom.

16. The stacked AW filter package of claim 15, wherein the diameter of the continuous circular region is greater than 360 µm.

17. The stacked AW filter package of claim 5, further comprising: A third substrate, wherein a second AW filter circuit is included on a second surface of the third substrate; and a second frame disposed on the second surface of the third substrate; wherein: the first substrate is disposed on the second frame to form a second cavity between the second AW filter circuit and the first substrate.

18. The stacked AW filter package as described in request item 17, wherein: The first substrate further includes a sidewall surface orthogonal to the first surface of the first substrate; the second frame is disposed between the second surface of the first substrate and the third substrate, extending from the sidewall surface of the first substrate on a first side in a direction orthogonal to the sidewall surface of the first substrate; and the second surface of the third substrate includes a shoulder region on a second side of the sidewall surface of the first substrate in a direction orthogonal to the sidewall surface of the first substrate.

19. The stacked AW filter package as described in request item 18, wherein: The at least one metal interconnect is disposed on: the sidewall surface of the first substrate; and the lower shoulder region of the second surface of the third substrate.

20. The stacked AW filter package of claim 19 further includes a surface interconnect extending from the interior of the second cavity to the lower shoulder region on the second surface of the third substrate, the surface interconnect being electrically coupled to the second AW filter circuit, and the at least one metal interconnect on the lower shoulder region.

21. The stacked AW filter package of claim 19, wherein the at least one metal interconnect is disposed on one side surface of the second frame between the first substrate and the third substrate.

22. The stacked AW filter package as described in request item 21, wherein: The second frame extends in a direction orthogonal to the sidewall surface of the first substrate to the lower shoulder region on the second side of the sidewall surface of the first substrate; and the at least one metal interconnect is disposed on a top surface of the second frame.

23. A method for manufacturing a stacked acoustic wave (AW) filter package, the method comprising: A first substrate is formed, including a first surface; an AW filter circuit is formed on the first surface of the first substrate; A frame is formed on the first surface of the first substrate; a second substrate is formed including a contact surface and a sidewall surface; the second substrate is disposed on the frame to form a cavity between the AW filter circuit and the second substrate; and a metallization layer is formed including at least one metal interconnect coupled to the contact surface of the second substrate and the first surface of the first substrate, the at least one metal interconnect being disposed on the sidewall surface of the second substrate; wherein the frame further includes a perimeter frame disposed along a perimeter of the second substrate, and a frame member extending into the cavity and orthogonal to at least a portion of the perimeter frame; and wherein the cavity is surrounded by the perimeter frame.

24. The method of claim 23 further includes: The frame is disposed between the first surface of the second substrate and the first substrate, and extends from the sidewall surface of the second substrate on a first side of the sidewall surface of the second substrate in a direction orthogonal to the sidewall surface of the second substrate; and a shoulder region of the first surface of the first substrate is formed on a second side of the sidewall surface of the second substrate in a direction orthogonal to the sidewall surface of the second substrate.

25. A stacked acoustic wave (AW) filter package, comprising: A first substrate including a first surface and a sidewall surface; a first AW filter circuit on the first surface of the first substrate; A first frame disposed on the first surface of the first substrate; a second substrate including a contact surface and a sidewall surface, the second substrate being disposed on the first frame to form a first cavity between the first AW filter circuit and the second substrate; a third substrate including a second AW filter circuit on a second surface of the third substrate; a second frame disposed on the second surface of the third substrate; and the first substrate disposed on the second frame to form a second cavity between the second AW filter circuit and the first substrate. A metallization layer comprising at least one metal interconnect coupled to the contact surface of the second substrate and the second surface of the third substrate, the at least one metal interconnect being disposed on the sidewall surface of the first substrate; and an insulator disposed on the sidewall surface of the first substrate and between the sidewall surface of the first substrate and the at least one metal interconnect.

26. The stacked AW filter package of claim 25, wherein the insulator is disposed between the at least one metal interconnect and the first frame.

27. The stacked AW filter package of claim 25, wherein the insulator is disposed between the at least one metal interconnect and the first surface of the first substrate.

28. The stacked AW filter package of claim 25, wherein the insulator is disposed between the at least one metal interconnect and the sidewall surface of the second substrate.

29. The stacked AW filter package of claim 26 further includes a through-hole extending from the contact surface through the second substrate to the first surface of the first substrate.

30. The stacked AW filter package of claim 29 further includes a contact pad on the contact surface, wherein: The contact pad is configured to conduct electrical signals; and the via is configured to electrically couple the first AW filter circuit to the contact pad.

31. As in request item 26, a stacked AW filter package, wherein: The thickness of the third substrate in a first direction orthogonal to a second surface is in the range of 60 to 130 micrometers (µm); the thickness of the first substrate in the first direction is in the range of 30 to 70 µm; and the thickness of the second substrate in the first direction is in the range of 30 to 70 µm.

32. The stacked AW filter package as described in request item 31, wherein: The thickness of the third substrate is less than 85 µm; the thickness of the first substrate is less than 55 µm; and the thickness of the second substrate is less than 55 µm.

33. A method for forming a stacked acoustic wave filter (AW filter) package, comprising: A first substrate is formed, comprising a first surface and a sidewall surface; A first AW filter circuit is formed on the first surface of the first substrate; a first frame is formed on the first surface of the first substrate; a second substrate including a contact surface and a sidewall surface is formed; the second substrate is disposed on the first frame to form a first cavity between the first AW filter circuit and the second substrate; a third substrate is formed, the third substrate including a second AW filter circuit on a second surface of the third substrate; a second frame is formed on the second surface of the third substrate; the first substrate is disposed on the second frame to form a second cavity between the second AW filter circuit and the first substrate; an insulator is formed on the sidewall surface of the first substrate; and a metallization layer including at least one metal interconnect coupled to the contact surface of the second substrate and the second surface of the third substrate is formed, the at least one metal interconnect being disposed on the insulator on the sidewall surface of the first substrate.

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