Encapsulated surface acoustic wave device

Abstract

A packaged surface acoustic wave (SAW) device and its manufacturing method are provided. The packaged SAW device is relatively thin and can have a height of less than 220 micrometers. The packaged SAW device includes a photosensitive resin over a conductive structure formed by an electroplating process. The conductive structure can be coated on a cavity defining structure encapsulating the SAW device, the cavity defining structure including walls and a top. The photosensitive resin may contain phenolic resin. The photosensitive resin can be relatively thin. The edge portion of the piezoelectric substrate may not have the photosensitive resin. This application also provides a laser-marked packaged SAW device and its manufacturing method. A laser can be used to directly mark the opposite side of the piezoelectric substrate supporting the packaged SAW device. By directly marking the piezoelectric substrate itself, the use of a separate marking film can be avoided, making the packaged SAW device thinner.

Description

[0001] Cross-reference to priority claims

[0002] Pursuant to 37 C. FR § 1.57, any and all applications identified in the application data sheet filed together with this application that claim foreign or domestic priority are incorporated herein by reference. This application claims priority to U.S. Provisional Application No. 62 / 725,133, filed August 30, 2018, entitled “PACKAGED SURFACE ACOUSTIC WAVE DEVICES,” the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] Embodiments of this application relate to encapsulated surface acoustic wave devices. Background Technology

[0004] Surface acoustic wave (SAW) filters may include multiple SAW resonators configured to filter radio frequency (RF) signals. Each resonator may include a SAW device. SAW filters can be implemented in radio frequency electronic systems. For example, a filter in the RF front-end of a mobile phone may include a SAW filter. Multiple SAW filters may be arranged as a multiplexer. For example, two SAW filters may be arranged as a duplexer.

[0005] Surface acoustic wave (SAW) devices can be enclosed in a package for protection. However, packaging increases the size of the encapsulated SAW device. Smaller and thinner encapsulated SAW devices are desired. Summary of the Invention

[0006] Each innovation described in the claims has multiple aspects, none of which is solely responsible for its desired properties. Some of the significant features of this application will now be briefly described without limiting the scope of the claims.

[0007] One aspect of this application is a packaged surface acoustic wave (SAW) device. The packaged SAW device includes a cavity top on the interdigital transducer electrodes of the SAW device, a conductive structure above the cavity top, and a photosensitive buffer coating above the conductive structure. The packaged SAW device has a height of 220 micrometers or less.

[0008] The encapsulated surface acoustic wave device can have a height of 200 micrometers or less. The photosensitive buffer coating can have a height of 15 micrometers or less.

[0009] The packaged surface acoustic wave device may further include: a piezoelectric substrate having a first side on which the interdigital transducer electrode is disposed; and a cavity wall located on the first side of the piezoelectric substrate and supporting the top of the cavity. The edge portion of the first side of the piezoelectric substrate may be without the photosensitive buffer coating.

[0010] The packaged surface acoustic wave device may further include a piezoelectric substrate having a first side and a second side opposite to the first side, the interdigitated transducer electrode being located on the first side, and a marker extending into the second side, the marker extending into the piezoelectric substrate at a depth of 1 micrometer or less. The packaged surface acoustic wave device of claim 1 may further include terminals that are in physical contact with the conductive structure through openings in the photosensitive buffer coating.

[0011] The photosensitive buffer coating may include a phenolic resin. The photosensitive buffer coating may have negative photosensitivity.

[0012] The surface acoustic wave device may include multiple surface acoustic wave resonators configured to filter radio frequency signals.

[0013] Another aspect of this application is a packaged surface acoustic wave device comprising: a cavity structure supported by a die and cooperating with the die to encapsulate interdigitated transducer electrodes of the surface acoustic wave device; a conductive structure extending on a portion of the outer surface of the cavity structure; and an insulating layer extending on the conductive structure, a portion of the insulating layer being disposed on a portion of the conductive structure, having a thickness of less than 15 micrometers.

[0014] The cavity structure may include a cavity wall supported by a first surface of the wafer and a cavity top extending onto the interdigital transducer electrodes and supported by the cavity wall. The packaged surface acoustic wave device may further include a plurality of terminals, each of which extends through a portion of the insulating layer and contacts a portion of the conductive structure.

[0015] The insulating layer may include a photoresist material. The insulating layer may include a negative photoresist.

[0016] The wafer may include a laser-marked piezoelectric substrate having a first side and a second side, the first side supporting the cavity structure, and the second side of the laser-marked piezoelectric substrate having a laser-marked section.

[0017] Another aspect of this application is a packaged surface acoustic wave device comprising: a piezoelectric substrate; a package structure supported by a first surface of the piezoelectric substrate and defining a cavity, the package structure including an outer layer comprising a photosensitive resin; and a plurality of interdigital transducer electrodes supported by the piezoelectric substrate and located within the cavity.

[0018] The packaging structure may include a cavity top and a cavity wall, both of which are located between a portion of the outer layer and the plurality of interdigital transducer electrodes.

[0019] The package structure may include a conductive structure electrically connected to at least one of the plurality of interdigital transducer electrodes. The package structure may include at least one terminal disposed on a portion of the outer layer and extending through the portion of the outer layer to contact the conductive structure.

[0020] Another aspect of this application is a method of manufacturing a packaged surface acoustic wave device, the method comprising: forming a photosensitive resin over a conductive structure, a portion of which is located on top of a cavity above interdigital transducer electrodes of the surface acoustic wave device; and forming a conductive terminal in contact with the conductive structure, at least a portion of which extends through a pore extending through the photosensitive resin.

[0021] The method may further include exposing portions of the photosensitive resin to light to develop the portions of the photosensitive resin and removing unexposed portions of the photosensitive resin. The method may additionally include curing the photosensitive resin after removing the unexposed portions. Exposing the portions of the photosensitive resin to light may include masking a portion of the photosensitive resin extending over a portion of the conductive structure to form the pores extending through the photosensitive resin.

[0022] Forming the terminal may additionally include forming a conductive layer extending over the pore that extends through the photosensitive resin. The pore may extend through a portion of the photosensitive resin having a thickness of 15 micrometers or less.

[0023] The photosensitive resin may include phenolic resin. The photosensitive resin may have negative photosensitivity.

[0024] The method may additionally include laser marking of the piezoelectric substrate on which the interdigital transducer electrodes are disposed.

[0025] The packaged surface acoustic wave device can have a height of less than 220 micrometers.

[0026] Another aspect of this application is a method for manufacturing a packaged surface acoustic wave device, the method comprising: forming a cavity structure for encapsulating interdigital transducer electrodes of the surface acoustic wave device, each interdigital transducer electrode being supported by a piezoelectric substrate; forming conductive structures extending over portions of the outer surface of the cavity structure; and forming a photoresist layer over the conductive structure, a portion of the photoresist layer extending over a portion of the conductive structure having a thickness of less than 15 micrometers.

[0027] The method may additionally include patterning the photoresist layer to form a photoresist buffer coating extending over the conductive structure and the cavity structure, and curing the photoresist layer. The photoresist buffer coating may include a portion that contacts the piezoelectric substrate and surrounds the sidewall of the cavity structure. A portion of the conductive structure may contact the piezoelectric substrate.

[0028] Forming the photoresist layer over the conductive structure may include using a spin-on process to planarize the photoresist layer. This method may additionally include removing a portion of the photoresist layer within 10 micrometers of the wafer edge.

[0029] Another aspect of this application is a method for manufacturing a packaged surface acoustic wave device, the method comprising: forming a cavity structure extending over interdigitated transducer electrodes of the surface acoustic wave device; forming conductive structures extending over portions of an outer surface of the cavity structure; and forming a photosensitive resin layer on the conductive structure, a portion of the photosensitive resin layer having pores extending through it and exposing a portion of the conductive structure.

[0030] Forming the conductive structure may include depositing a seed layer on the cavity structure and electroplating the conductive structure onto the seed layer. Forming the conductive structure may further include masking portions of the seed layer before electroplating the conductive structure onto the seed layer.

[0031] The conductive structure may include a gap extending through a portion of it and exposing a portion of the cavity structure, and the photosensitive resin layer may fill the gap. The method may additionally include forming conductive terminals extending through pores in the photosensitive resin layer and electrically connected to the conductive structure.

[0032] Another aspect of this application is a packaged surface acoustic wave device comprising: a piezoelectric substrate having a first side and a second side; interdigitated transducer electrodes encapsulated within a package structure and supported by the first side of the piezoelectric substrate; and a mark formed in the second side of the piezoelectric substrate.

[0033] The mark can extend into the second side of the piezoelectric substrate to less than 1 micrometer. The mark can extend into less than 1% of the thickness of the piezoelectric substrate. The mark can be formed by laser.

[0034] The piezoelectric substrate may include lithium niobate. The piezoelectric substrate may include lithium tantalate.

[0035] The encapsulation structure may include a cavity structure encapsulating the interdigital transducer electrodes and an outer coating including a photosensitive resin. The total thickness of the encapsulated surface acoustic wave device may be less than 220 micrometers.

[0036] The packaging structure may include a photosensitive resin buffer coating. The photosensitive resin buffer coating may include a phenolic resin. The photosensitive resin buffer coating may include a negative photoresist. The surface acoustic wave device in the package may additionally include a plurality of terminals extending through the pores in the photosensitive resin buffer coating.

[0037] Another aspect of this application is a packaged surface acoustic wave device comprising: a laser-marked piezoelectric substrate having a first side and a second side, the second side of the laser-marked piezoelectric substrate having a laser-marked section; an interdigital transducer electrode supported by the first side of the laser-marked piezoelectric substrate; and a structure supported by the first side of the laser-marked piezoelectric substrate defining a cavity enclosing the interdigital transducer electrode.

[0038] The laser-marked section may have been exposed to deep ultraviolet laser light. The laser-marked section may include a laser mark less than 1 micrometer extending to the second side of the piezoelectric substrate.

[0039] The laser-marked piezoelectric substrate may include lithium niobate. The laser-marked piezoelectric substrate may include lithium tantalate.

[0040] The packaging structure may include a photosensitive resin buffer coating. The photosensitive resin buffer coating may include a phenolic resin. The photosensitive resin buffer coating may include a negative photoresist. Another aspect of this application is a method for marking a packaged surface acoustic wave device, the method comprising: grinding the back side of a piezoelectric substrate, the back side being opposite to the front side of the piezoelectric substrate on which interdigital transducer electrodes of the surface acoustic wave device are disposed; and laser marking the piezoelectric substrate.

[0041] Laser marking can form marks less than 1 micrometer extending into the piezoelectric substrate. The laser marking may include a wavelength of laser light that allows the piezoelectric substrate to maintain structural integrity.

[0042] The laser marking may include the use of a deep ultraviolet laser. The laser marking may include the use of a laser with a wavelength of approximately 266 nanometers.

[0043] Polishing the back side of the piezoelectric substrate may include polishing the back side of the piezoelectric substrate until the thickness of the piezoelectric substrate is about 130 micrometers.

[0044] The piezoelectric substrate may include lithium niobate. The method of claim 62, wherein the piezoelectric substrate may include lithium tantalate.

[0045] The method may further include forming a structure supported by the front side of the piezoelectric substrate and defining a cavity enclosing the interdigital transducer electrode. This structure supported by the front side of the piezoelectric substrate may be formed before grinding the back side of the piezoelectric substrate. Forming this structure supported by the front side of the piezoelectric substrate may include forming a photosensitive resin buffer coating.

[0046] Another aspect of this application is a method for marking a packaged surface acoustic wave device, the method comprising: forming a package structure on a first surface of a piezoelectric substrate, wherein interdigital transducer electrodes of the surface acoustic wave device are disposed on the first surface of the piezoelectric substrate, the package structure encapsulating the interdigital transducer electrodes in a cavity; and directly marking a second surface of the piezoelectric substrate to form a marking portion of the piezoelectric substrate.

[0047] Directly marking the second surface of the piezoelectric substrate may involve exposing the marked portion of the second surface of the piezoelectric substrate to a laser. The laser may include deep ultraviolet light. The laser may have a wavelength of approximately 266 nanometers.

[0048] Forming an encapsulation structure may include forming a photosensitive resin layer and patterning the photosensitive resin layer. The photosensitive resin may include a phenolic resin. Forming the encapsulation structure may include forming conductive terminals extending through the photosensitive resin layer.

[0049] The mark can extend into the piezoelectric substrate to a depth of less than 1 micrometer. The packaged surface acoustic wave device can have a thickness of less than 220 micrometers.

[0050] Another aspect of this application is a packaged surface acoustic wave device comprising a cavity top on an interdigital transducer of the surface acoustic wave device, a plate above the cavity top, and a photosensitive buffer coating on the plate, the packaged surface acoustic wave device having a height of 220 micrometers or less.

[0051] The encapsulated surface acoustic wave device can have a height of 200 micrometers or less. The photosensitive buffer coating can have a height of 15 micrometers or less.

[0052] The packaged surface acoustic wave device may additionally include a piezoelectric substrate having a first side on which the interdigital transducers are disposed, and the edge portion of the first side of the piezoelectric substrate may be without the photosensitive buffer coating.

[0053] The packaged surface acoustic wave device may additionally include a piezoelectric substrate having a first side and a second side opposite to the first side, wherein interdigitated transducers may be located on the first side, and a marking may extend into the second side. The marking may extend into the piezoelectric substrate to 1 micrometer or less.

[0054] The surface acoustic wave device in the package may additionally include terminals that physically contact the board through openings in the photosensitive buffer coating.

[0055] The photosensitive buffer coating may include a phenolic resin. The photosensitive buffer coating may have negative photosensitivity.

[0056] The packaged surface acoustic wave device may include a surface acoustic wave device configured to filter radio frequency signals.

[0057] Another aspect of this application is a packaged surface acoustic wave device comprising: a piezoelectric substrate having a first side and a second side opposite to the first side, the second side having a mark extending therein; a cavity top located on the interdigital transducer of the surface acoustic wave device on the first side of the piezoelectric substrate; a plate located above the cavity top; and an insulating layer located above the plate.

[0058] Another aspect of this application is a packaged surface acoustic wave device, comprising: a piezoelectric substrate; a cavity top located on interdigital transducers of the surface acoustic wave device, the interdigital transducers being disposed above the piezoelectric substrate; a plate located above the cavity top; and an insulating layer located above the plate, wherein the edge portion of the piezoelectric substrate is free of the insulating layer.

[0059] Another aspect of this application is a packaged surface acoustic wave device comprising: a cavity top located above the interdigital transducers of the surface acoustic wave device; a plate located on the cavity top; and an insulating layer located above the plate, the insulating layer having a thickness of 10 micrometers or less, and the packaged surface acoustic wave device having a height of 200 micrometers or less.

[0060] Another aspect of this application is a method of manufacturing a packaged surface acoustic wave device, the method comprising: forming a photosensitive resin over a plate placed above a cavity enclosing an interdigital transducer of the surface acoustic wave device; and forming a terminal of the surface acoustic wave device over the photosensitive resin such that the terminal contacts the plate.

[0061] The method may additionally include exposing portions of the photosensitive resin to light and providing openings through the photosensitive resin to other portions of the photosensitive resin, wherein forming the terminal may include filling the openings with the material of the terminal.

[0062] The method may additionally include exposing the photosensitive resin to light and providing other portions of the photosensitive resin with the edge of a piezoelectric substrate free of the photosensitive resin, and the interdigital transducer electrodes may be placed on the piezoelectric substrate.

[0063] The photosensitive resin may have a thickness of 15 micrometers or less. The photosensitive resin may include phenolic resin.

[0064] The method may additionally include laser marking of a piezoelectric substrate on which interdigital transducers are disposed.

[0065] Another aspect of this application is a method for marking a packaged surface acoustic wave device, the method comprising: grinding the back side of a piezoelectric substrate opposite to the front side of the piezoelectric substrate on which an interdigital transducer of the surface acoustic wave device is disposed; and laser marking the piezoelectric substrate.

[0066] The mark can extend into the piezoelectric substrate to a depth of less than 1 micrometer.

[0067] The laser marking may include a wavelength of laser applied that allows the piezoelectric substrate to maintain structural integrity. The laser marking may include the use of a deep ultraviolet laser.

[0068] To provide an overview of this application, specific aspects, advantages, and novel features of the application have been described herein. It should be understood that not all such advantages need to be realized according to any particular embodiment. Therefore, the application may be implemented or practiced in a manner that achieves or optimizes one or more advantages taught herein without necessarily realizing other advantages that may be taught or implied herein. Attached Figure Description

[0069] With reference to the accompanying drawings, embodiments of this application will now be described by way of non-limiting examples.

[0070] Figure 1 This is a cross-sectional view of a packaged surface acoustic wave device according to one embodiment.

[0071] Figure 2A This is another cross-sectional view of a packaged surface acoustic wave device according to another embodiment. Figure 2B yes Figure 2A Detailed diagram of section B.

[0072] Figures 3A to 3J It is a cross-section of a portion of the packaged surface acoustic wave device during various stages of the manufacturing process according to one embodiment.

[0073] Figures 4A to 4F It is a cross-section of a portion of a surface acoustic wave device packaged as part of a manufacturing process including multiple photoresist exposures according to another embodiment.

[0074] Figures 5A to 5E It is a cross-section of a portion of an encapsulated surface acoustic wave device, which is part of a manufacturing process including an electroplating process according to another embodiment.

[0075] Figures 6A to 6C It is a cross-section of a portion of a surface acoustic wave device packaged as part of a manufacturing process including a spin coating procedure according to another embodiment.

[0076] Figure 7 This is a flowchart of a process for manufacturing a surface acoustic wave device including a photosensitive buffer coating according to one embodiment.

[0077] Figure 8 This is a flowchart of a process for manufacturing a packaged surface acoustic wave device including a piezoelectric layer with laser markings, according to one embodiment.

[0078] Figure 9This is a schematic diagram of an RF module including a filter with a SAW resonator according to one embodiment.

[0079] Figure 10 This is a schematic diagram of a radio frequency module including a duplexer with a surface acoustic wave resonator, according to one embodiment.

[0080] Figure 11 This is a schematic block diagram of a module including a power amplifier, a radio frequency switch, and a duplexer (which includes one or more surface acoustic wave resonators) according to one embodiment.

[0081] Figure 12 This is a schematic block diagram of a module including a low-noise amplifier, an RF switch, and a surface acoustic wave filter according to one embodiment.

[0082] Figure 13 This is a schematic block diagram of a module including an antenna switch and a duplexer (which includes one or more surface acoustic wave resonators) according to one embodiment.

[0083] Figure 14 This is a schematic block diagram of a wireless communication device including a surface acoustic wave filter according to one or more embodiments.

[0084] Figure 15 This is a schematic block diagram of another wireless communication device including a surface acoustic wave filter according to one or more embodiments. Detailed Implementation

[0085] The following description of specific embodiments presents various descriptions of particular embodiments. However, the innovations described herein, such as those defined and covered by the claims, can be implemented in many different ways. In the specification, reference is made to the drawings, wherein the same reference numerals may indicate the same or functionally similar elements. It should be understood that the elements shown in the drawings are not necessarily drawn to scale. Furthermore, it should be understood that particular embodiments may include more elements than those shown in the drawings and / or a subset of the elements drawn in the drawings. In addition, some embodiments may incorporate any suitable combination of features from two or more drawings.

[0086] As competition in the semiconductor market intensifies, there is a growing need for smaller and thinner surface acoustic wave (SAW) devices. For example, in certain applications, specifications require SAW device package heights of 200 micrometers or less, enabling the packaged SAW device to be fitted into modules. This paper discloses packaging methods that enable smaller size and lower cost for SAW devices. It also discloses SAW devices with wafer-level chip-scale packages (WL-CSP) for SAW filters with thinner packages.

[0087] Methods for reducing package height and / or lowering package cost of packaged surface acoustic wave (SAW) devices are disclosed herein. The package structure disclosed herein includes a photosensitive buffer coating that acts as a protective layer overlaying a copper (Cu) plating. Using a thin photosensitive buffer coating, a package structure without pillar structures connecting terminals to the internal conductive structure of the package can be formed. The package structure disclosed herein includes markings on the piezoelectric substrate of the SAW device. Laser marking of the piezoelectric substrate can be performed without damaging its function. The package structure disclosed herein meets electrical performance and molding strength specifications. The packaged SAW device disclosed herein may include a SAW filter configured to filter radio frequency (RF) signals.

[0088] Figure 1 This is a cross-sectional view of a packaged surface acoustic wave (SAW) device according to one embodiment. Certain aspects of the packaged SAW device 100 allow for a reduction in package thickness. For example, the packaged SAW device 100 may have a package height H1 of less than 220 micrometers (μm). In some embodiments, the package height H1 may be less than 200 μm. In one exemplary embodiment, the packaged SAW device 100 has a package height H1 of approximately 190 μm.

[0089] like Figure 1 As shown, the packaged surface acoustic wave device 100 includes a wafer 102 and interdigitated transducer electrodes 104 on the wafer 102. The wafer 102 is a piezoelectric substrate. The wafer 102 may include a lithium-containing piezoelectric material, such as, for example, lithium niobate or lithium tantalate. In some examples, the wafer 102 includes a multilayer piezoelectric substrate. In some instances, the wafer 102 may be about 130 μm high. Other suitable thicknesses may also be used in other embodiments.

[0090] The wafer 102 may include a marking segment 108 on one side of the wafer 102 opposite to the interdigitated transducer electrode 104. The marking segment 108 may be relatively shallow compared to the total thickness of the wafer 102. In some embodiments, the marking of the marking segment 108 may extend into the wafer to less than 1 μm. By marking directly into the wafer 102, no additional marking film is included. Figure 1 The surface acoustic wave device 100 is encapsulated. This reduces the overall height of the encapsulated surface acoustic wave device 100 relative to the encapsulated surface acoustic wave device including the marking film.

[0091] Interdigitated transducer electrodes 104 of the surface acoustic wave (SAW) resonator are disposed on wafer 102. The SAW resonator can be arranged as a filter configured to filter radio frequency (RF) signals. Any suitable number of SAW resonators and / or SAW filters can be included in the packaged SAW device 100.

[0092] Interdigitated transducer electrodes 104 may be disposed within a cavity 116. Each side of the cavity 116 is formed by cavity walls 112 supported by the wafer 102. The top of the cavity 116 is formed by a cavity top 114 supported by the cavity walls 112 and extending above the interdigitated transducer electrodes 104. The cavity 116 may be an air cavity. In some embodiments, the cavity 116 may be approximately 25 μm high, but other suitable cavity heights may also be used.

[0093] In some embodiments, one or both of the cavity top 114 and the cavity wall 112 may include a photoresist material, as will be discussed in more detail below.

[0094] A portion of the outer surface of the cavity top 114 and cavity wall 112 is covered by a conductive layer 122. In some embodiments, the conductive layer 122 may be formed by covering the outer surface of the cavity top 114 and cavity wall 112 with a seed layer and then using an electroplating process to form the conductive layer 122 on the seed layer. The conductive layer 122 may include more than one segment, which may be electrically isolated from each other by at least one gap 124 in the conductive layer 122. In some embodiments, the conductive layer 122 may be about 25 μm thick, but other suitable thicknesses may also be used.

[0095] In some embodiments, the conductive layer 122 includes a copper layer plated onto a seed layer comprising copper and / or titanium.

[0096] The conductive layer 122 may extend along each side of the cavity wall 112 and downward to the wafer 102, wherein the conductive layer 122 may contact interconnect structures (such as electronic traces) on the wafer 102, which allows electrical communication with the interdigital transducer electrodes 104 of the surface acoustic wave resonator structure within the packaged surface acoustic wave device 100. In some applications, the conductive layer 122 may be referred to as an electroplated layer.

[0097] An insulating layer 132 extends above the outer surface of the conductive layer 122 and fills the gaps 124 in the conductive layer 122. Each side portion 136 of the insulating layer 132 extends downward along each side 126 of the conductive layer 122 to the wafer 102. In a particular embodiment, the insulating layer 132 is a photosensitive resin. In some embodiments, the conductive layer 122 may be a negative photoresist. In some embodiments, the photosensitive resin may be a phenolic resin with rubber filler. Such a resin may have a viscosity of about 700 centipoise (cP) and a shelf life of about 9 months at 5°C and a workshop life of about 4 months. The cured resin may have a Young's modulus of about 2.2 gigapascals (GPa) and a coefficient of thermal expansion of about 55°C.

[0098] The insulating layer 132 can be made relatively thin. In some embodiments, the insulating layer may be about 15 μm thick or less. In some embodiments, the thickness of the insulating layer 132, comprising a phenolic resin with rubber filler, may range from about 6 μm to about 14 μm. In some specific embodiments, the thickness of the insulating layer 132, comprising a phenolic resin with rubber filler, may be about 10 μm. Using a material such as a photosensitive resin to form the insulating layer 132 can reduce the overall height of the packaged surface acoustic wave device 100 relative to other devices with thicker insulating layers.

[0099] In addition to reducing thickness, the photosensitive buffer coating, which serves as the insulating layer 132, can also be removed to ensure that there are no noticeable residues on other parts of the wafer 102 (such as openings and dicing areas for dicing and monolithizing the wafer). The photosensitive buffer coating also provides good coverage of the copper conductive layer surface, and there is no significant copper oxidation after the buffer coating cures. The photosensitive buffer coating can also pass ball shear and reliability tests.

[0100] The insulating layer 132 may be a photosensitive buffer coating. In some embodiments, a negative photosensitive material may be used as the photosensitive buffer coating. Due to the trenches formed by the cavity walls, cavity top, and the height of the conductive layer, the photosensitive buffer coating can be thicker at the cut edges of the device. For positive photosensitive materials, the exposure energy can be a significant factor in removing residues when the area of ​​the photosensitive material to be removed is exposed to light. A relatively high exposure dose can be applied to develop the positive photosensitive material to penetrate the relatively thick buffer coating at the edges of the device. This makes it difficult to develop the positive material when the exposure energy is not high enough. Using a relatively high exposure energy can thin the edges to near the cut edges.

[0101] In contrast, for negative photosensitive materials, the photosensitive buffer area that is desired to remain in the finished device is exposed to light. The development rate can depend on the properties of the photosensitive material. Negative photosensitive materials can be easily developed in the cut-out area on the side of the packaged surface acoustic wave device.

[0102] The packaged surface acoustic wave device 100 also includes terminals 142a and 142b, which are located above respective portions of the conductive layer 122 and are in physical contact with the conductive layer 122 through apertures 134 in the insulating layer 132. Portions 144a and 144b of terminals 142a and 142b extend through the apertures in the insulating layer 132, respectively. Solder layers 146a and 146b are respectively applied to terminals 142a and 142b.

[0103] A conformal layer overlying the patterned insulating layer 132 can form both the connecting portions 144a and 144b and the remaining portions of the terminals 142a and 142b. In such an embodiment, terminals and an underlying conductive layer can be formed without separate pillars connecting them. The terminals may comprise copper or another suitable material. In some embodiments, the terminals may have a thickness of about 10 μm. Solder layers 146a and 146b may comprise tin.

[0104] Figure 2A This is a diagram of a packaged surface acoustic wave device 200 according to one embodiment. Figure 2B yes Figure 2A A detailed view of section B shows the edge portion of the packaged surface acoustic wave device 200. (See attached image.) Figure 2B As can be seen, the cavity wall 212 has a thickness TW, and the sidewall 226 of the conductive material 222 along the edge of the device has a thickness T. C And the distance from the outer edge of the sidewall 236 of the conductive material 232 to the edge of the wafer 202 has a thickness T. E In some embodiments, the thickness T of the cavity wall 212 W The thickness T of the portion of the sidewall 226 of the conductive material 222 in contact with the wafer 202 is approximately 30 μm. C The thickness T is approximately 15 μm, and the distance from the outer edge of the sidewall 236 of the conductive material 232 to the edge of the wafer 202 is... E It is approximately 30 μm.

[0105] Figure 2B The photosensitive resin at the edge portion 206 of the wafer substrate is shown to be free of the insulating layer 232, such that the side 236 of the insulating layer 232 is offset from the outer edge of the wafer 202. The edge portion can extend from the edge of the insulating layer 232 to the edge of the wafer 202 by a distance ranging from approximately 10 μm to approximately 20 μm. This allows the dicing area where the wafer is cut and monolithically sized to be free of the insulating layer. This, in turn, allows for the use of relatively thin blades for wafer monolithization. This facilitates smaller spacing between adjacent wafers and more wafers on a given wafer size. Furthermore, thinner blades used for monolithization can improve reliability by reducing debris.

[0106] Figures 3A to 3J This is a cross-section of a portion of the packaged surface acoustic wave device during various stages of the manufacturing process according to one embodiment. Figure 3AIn the illustrated stage, a die 302 is provided, which includes interdigital transducer electrodes 304 of one or more surface acoustic wave (SAW) resonators. In some embodiments, the die 302 may be a wafer having multiple discrete regions containing interdigital transducer electrodes, which will be packaged into a separate packaged SAW device and then separated in a single-die process. The die 302 may be a single piezoelectric layer, as shown in the figure. In other embodiments, the die 302 may be a multilayer piezoelectric substrate, which includes a support substrate and a piezoelectric substrate. The multilayer piezoelectric substrate may include one or more additional layers and a support substrate and a piezoelectric substrate. As an example, the support substrate may be a silicon substrate. In addition to the interdigital transducer electrodes 304, interconnect structures extending away from the interdigital transducer electrodes 304 may also be provided on the die 302.

[0107] exist Figure 3B In the process, a cavity wall 312 has been formed surrounding the interdigital transducer electrode 304. The cavity wall 312 may be a single wall with curved sections, or it may include multiple wall sections that intersect each other at an angle to form a desired shape (such as a rectangle). The cavity wall 312 may include photoresist or other photosensitive materials. The height of the cavity wall 312 may correspond to the required height of the resulting cavity. The cavity wall 312 may extend over an interconnect structure supported by the wafer 302, such that a portion of the interconnect structure is located outside the cavity wall 312. Each cavity wall 312 may be formed across a wafer including piezoelectric material at multiple locations, each at a location where a package is formed.

[0108] exist Figure 3C In this embodiment, a cavity top 314 has been formed, extending from one side of the cavity wall 312 to the other. In the illustrated embodiment, the cavity top 314 is a flat structure having an upper surface and a lower surface that extend generally parallel to each other and parallel to the lower surface of the wafer 302. In some other embodiments, other shapes of the cavity top may be formed, including shapes having grooves in the lower surface of the cavity top facing the interdigital transducer electrodes 304. In the illustrated embodiment, the edges of the cavity top 314 do not extend outward beyond the edges of the cavity wall 312. This shape facilitates subsequent material deposition on the cavity-defined structure.

[0109] exist Figure 3D In this process, a seed layer has been deposited on the outer surfaces of the cavity top 314 and the cavity wall 312, and a conductive layer 322 has been formed at certain locations covering the seed layer. The conductive layer 322 includes a gap 324 between two portions of the conductive layer 322. The conductive layer 322 also includes a sidewall portion 326 that extends along the sides of the cavity top 314 and the cavity wall 312 and downwards to the wafer 302.

[0110] exist Figure 3EIn the process, the exposed portion of the seed layer has been removed, and a buffer insulating coating 332 has been formed above the conductive layer 322. The insulating layer 332 has apertures 334 exposing a lower section of the conductive layer 322. The insulating layer 332 also includes sidewall portions 336 extending along the side of the conductive layer 322 and downward to the wafer 302. The insulating layer 332 may include a negative photosensitive material. The insulating layer 332 may include a photosensitive resin. The insulating layer 332 may include a phenolic resin with rubber filler.

[0111] exist Figure 3F Terminals 340a and 340b have been formed over the pores 334 of the insulating layer 332. Terminals 340a and 340b fill at least a portion of the pores 334 and extend over portions of the insulating layer 332 adjacent to the pores 334. In some embodiments, terminals 340a and 340b may comprise copper or another suitable conductive material. Terminals 340a and 340b may include a conformal material layer deposited over the pores 334 and portions of the insulating layer 332 adjacent to the pores 334, such that terminals 340a and 340b include respective connecting portions 344a and 344b within the pores 334 and wider upper sections 342a and 342b above the connecting portions 344a and 344b.

[0112] exist Figure 3G Solder portions 346a and 346b have been formed on the upper surfaces of terminals 340a and 340b, respectively. In some embodiments, the solder may include tin, but other suitable solder materials may also be used. Solder portions 346a and 346b may enable terminals 340a and 340b to be coupled to external devices to achieve connection with the surface acoustic wave resonator within cavity 316 via conductive material 322.

[0113] exist Figure 3H In this process, the sides of the wafer 302 opposite the interdigital transducer electrodes 304 are back ground to remove a portion 309 of the wafer 302 to reduce the thickness of the wafer 302 to a desired final thickness. In some embodiments, the resulting trimmed wafer 302' may have a final thickness of about 130 μm, but other wafer thicknesses may also be used.

[0114] exist Figure 3I In this process, the side 307 of the trimmed wafer 302', which is opposite to the interdigital transducer electrode 304, is exposed to illumination 390 from a marking laser to form a marked and trimmed wafer 302" with a marking portion 308. The laser marking can be used to align modules and / or to identify batches of wafers and modules. Laser marking can be performed directly on the piezoelectric material of the trimmed wafer 302', as shown in the figure. By directly marking the trimmed wafer 302' instead of forming an additional film or layer to be marked, the overall thickness of the resulting packaged surface acoustic wave device 300 can be reduced.

[0115] This direct marking can be achieved using illumination 390 from a deep ultraviolet laser. In one embodiment, such a laser emits light with a wavelength that marks the lithium-based substrate without impairing the functionality of the surface acoustic wave device. For example, the laser could have a wavelength of 266 nanometers (nm). This laser wavelength, or a similar wavelength, can mark the lithium-based substrate (such as a lithium niobate substrate or a lithium tantalate substrate) to a relatively shallow depth, such as less than 1 micrometer. This shallow marking depth prevents a significant reduction in the intensity of the trimmed and marked wafer 302". Furthermore, this laser wavelength should not penetrate the lithium niobate substrate. Suitable laser wavelengths can be used similarly to mark multilayer piezoelectric substrates.

[0116] Figure 3J A detailed view of a marked, packaged surface acoustic wave device 300 is shown, including a marking portion 308 on the side surface 307 of a trimmed wafer 302' opposite to interdigital transducer electrodes 304. The detailed view shows a mark 392 in the marking portion 308 on the bottom side 307 of the wafer 302'. Any suitable marking can be formed, including letter and number markings or other symbols. The marking portion 308 can be located at any or several suitable locations on the wafer 302'.

[0117] The resulting packaged surface acoustic wave device 300 may have an overall package height H1 of less than 220 μm, and in some embodiments may be less than 200 μm or about 190 μm. Features of reducing the overall package height H1 of the device 300 include using a buffer coating to form the insulating layer 332 and directly marking the wafer 302" instead of forming and marking separate layers. Furthermore, in Figures 3A to 3J The process shown allows for the encapsulation of surface acoustic wave devices using fewer processing steps (e.g., about 25 fewer) than some previous methods.

[0118] although Figure 3B and Figure 3C The formation of the cavity wall 312 and the cavity top 314 is roughly shown, but Figures 4A to 4F A more detailed embodiment of the manufacturing process for forming the cavity walls and cavity top is shown. Specifically, Figures 4A to 4F The image shows a cross-section of a partially encapsulated surface acoustic wave device, illustrating various stages of the manufacturing process involving multiple photoresist exposures.

[0119] Figure 4A This illustrates the formation of a photosensitive layer 450 over a wafer 402 and an interdigital transducer electrode 404 supported by the wafer 402. The wafer 402 and the interdigital transducer electrode 404 may be similar to... Figure 3AThe wafer 302 and interdigital transducer electrodes 304 are included. The photosensitive layer 450 may include a photosensitive material and may be formed to have a thickness equal to the required thickness of the cavity walls. Because the interdigital transducer electrodes 404 and other components supported by the wafer 402 can provide an irregular upper surface on which the photosensitive layer 450 is formed, the photosensitive layer 450 can be formed using a liquid-type photosensitive material (such as a liquid photoresist). Using a liquid photosensitive material allows for the formation of a substantially constant thickness of the photosensitive layer 450 across the wafer 402 and above the interdigital transducer electrodes 404.

[0120] Figure 4B The illustration shows the use of a mask 452 to selectively expose portions of the photosensitive layer 450 to light 490. In the illustrated embodiment, the photosensitive layer 450 comprises a positive photosensitive material, wherein portions of the photosensitive layer 450 to be retained in the apparatus are shielded from light, while portions 454 of the photosensitive layer 450 to be removed are exposed to light. The masked portions of the photosensitive layer 450 remain insoluble in the photoresist developer, and the unmasked portions 454 of the photosensitive layer 450 exposed to light become soluble in the photoresist developer.

[0121] Figure 4C Show Figure 4B The mask portion of the photosensitive layer 450 remains as cavity wall 412 after the unmasked portion of the photosensitive layer is removed. This removal may include, for example, exposing the photosensitive layer 450 to a photoresist developer to remove soluble portions of the photosensitive layer.

[0122] exist Figure 4D In this process, a photoresist layer 460 has been formed above the cavity wall 412. Unlike a photoresist material 450, which may include a liquid-type photoresist to provide a constant thickness above an irregular surface, the photoresist layer 460 can be deposited as a film supported by the cavity wall, thereby forming a generally flat structure over the interdigital transducer electrode 404 and other components supported by the wafer 402.

[0123] exist Figure 4E In this embodiment, a mask 462 is used to selectively expose the photosensitive layer 460 to light 490. In the illustrated embodiment, the photosensitive layer 460 comprises a negative photosensitive material, wherein portions of the photosensitive layer 460 to be retained in the device are exposed to light, and portions 464 of the photosensitive layer 460 to be removed are shielded from light. The masked portions 464 of the photosensitive layer 460 remain soluble in the photoresist developer, and the unmasked portions of the photosensitive layer 460 exposed to light remain insoluble in the photoresist developer.

[0124] Figure 4F This shows the portion of the cavity top 414 left after the mask portion of the photosensitive layer is removed. Figure 4EThe unmasked portion of the photosensitive layer 460. This removal may include, for example, exposing the photosensitive layer 460 to a photoresist developer to remove soluble portions of the photosensitive layer.

[0125] although Figure 3D The formation of conductive layer 322 is roughly shown, but... Figures 5A to 5E A more detailed illustration of a specific embodiment of the manufacturing process using an electroplating procedure to form a conductive layer is provided. Specifically, Figures 5A to 5E It is a cross-section of a partially encapsulated surface acoustic wave device at various stages of the manufacturing process, including the electroplating process.

[0126] Figure 5A This shows that a seed layer 520 has been formed above the outer surface of the cavity wall 512 and the cavity top 514. (As shown) Figure 4F The partially packaged device has a cavity wall 512 and a cavity top 514 supported by a wafer 502 and defining a cavity 516 enclosing interdigital transducer electrodes 504 supported by the wafer 502. Forming a seed layer 520 may include performing surface modification on exposed surfaces or other surfaces of the cavity top 514, including cleaning these surfaces. Metal may then be sputtered onto the exposed surfaces of the cavity top 514 and the cavity wall 512 to form the seed layer 520. In some embodiments, titanium and copper may be sputtered to form a base metal for electroplating. The seed layer 520 may extend to the exposed portion of the wafer 502 adjacent to the cavity wall 512.

[0127] exist Figure 5B In this configuration, a photosensitive layer 570 has been formed above the seed layer 520. As shown in the figure, the photosensitive layer 570 can be substantially conformally formed on the underlying structure, but in other embodiments, it can be thinner above the cavity top 514 than above the wafer on the side. The photosensitive layer 570 can be made at least as thick as the final conductive layer electroplated onto the seed layer in the region covering the cavity top 514, so that the photosensitive layer 570 can be used to define the shape of the conductive layer electroplated onto the seed layer 520.

[0128] exist Figure 5C In this process, the photosensitive layer 570 has been patterned by selectively exposing the photosensitive layer 570 to light and then removing the soluble portions of the photosensitive layer 570. This removal and exposure of each portion of the photosensitive layer exposes portions of the seed layer 520.

[0129] The remaining photosensitive layer portion includes side portions 574 that define the edges of the conductive layer to be formed. These side portions 574 may cover only portions of the seed layer 520 on the underlying wafer 502 away from the cavity wall 512. The remaining photosensitive layer portion also includes gap defining portions 572 extending over a portion of the cavity top 514. In some embodiments, the gap defining portions 572 may extend from one side portion 574 to the other side portion 574 to completely separate the two exposed portions of the seed layer 520 from each other. In some embodiments, additional gap defining portions may be included that separate the exposed portions of the seed layer 530 into multiple separation segments.

[0130] exist Figure 5D In this process, a thicker conductive layer 522 has been electroplated onto the exposed portion of the seed layer 520. The shape of the thicker conductive layer 522 is defined by the remaining portion of the photosensitive layer, which includes a side portion 574 and a gap defining portion 572. The conductive layer 522 may include copper or any other suitable material.

[0131] exist Figure 5E In this process, the remaining portion of the photosensitive layer, including the side portion 574 and the gap defining portion 572, has been removed. Additionally, the exposed portion of the seed layer 520 beneath these portions of the photosensitive layer has been removed. The resulting conductive layer 522 may include discrete segments separated by gaps 524 covering the cavity top 514 and sidewall segments 526 extending downward along each side of the cavity top 514 and cavity wall 512 to the wafer 502.

[0132] although Figure 3E The formation of insulating layer 332 is roughly shown, but Figures 6A to 6C Specific embodiments of the manufacturing process for forming the insulating layer are shown in more detail. In particular, Figures 6A to 6C The image shows a cross-section of a portion of the packaged surface acoustic wave device at various stages of the manufacturing process, including the spin coating process.

[0133] Figure 6A This shows that a buffer coating 680 has been formed above the outer surface of the conductive layer 622, which is formed above the cavity wall 612 and the cavity top 614. As... Figure 5E The partial encapsulation device has a cavity wall 612 and a cavity top 614 supported by a wafer 602 and defining a cavity 616 enclosing the interdigital transducer electrodes 604 supported by the wafer 602. In some embodiments, the buffer coating may include a photosensitive resin, such as a phenolic resin. The buffer coating may also include a rubber filler.

[0134] In the illustrated embodiment, the thickness of the buffer coating 680 covering the conductive layer 622 is thinner than the thickness of the buffer coating 680 covering the wafer 602 located away from the conductive layer 622. The upper surface of the buffer coating 680 may be substantially flat. In some embodiments, a spin coating process may be used to deposit the buffer coating 680. Although the underlying conductive layer 622 and the wafer 602 have irregular contours, a substantially flat upper surface can be provided using a spin coating process. In some embodiments, the thickness of the buffer coating 680 covering the region on the cavity top 614 may be less than about 10 μm, but other suitable thicknesses may also be used.

[0135] exist Figure 6B In this embodiment, a mask 682 is used to selectively expose the buffer coating 680 to light 690. In the illustrated embodiment, the buffer coating 680 comprises a negative photosensitive material, wherein portions of the buffer coating 680 to be retained in the device are exposed to light, and portions 684 of the buffer coating 680 to be removed are shielded from light. The masked portions 684 of the buffer coating 680 remain soluble in the photoresist developer, and the unmasked portions of the light-exposed buffer coating 680 become insoluble in the photoresist developer. Broadband light can be used to expose the buffer coating 680.

[0136] exist Figure 6C In the process, the mask portion of the buffer coating 680 has been removed, and the remaining portion has been cured to form an insulating layer 632 extending over the conductive layer 622. The insulating layer 632 has apertures 634 exposing lower sections of the conductive layer 622. The insulating layer 632 also includes sidewall portions 636 extending downward along each side of the conductive layer 622 to the wafer 602.

[0137] Figure 7 This is a flowchart of a process for manufacturing a surface acoustic wave (SAW) device including a photosensitive buffer coating according to one embodiment. Process 700 begins at a stage 705, in which a cavity structure is formed on a wafer supporting at least one interdigital transducer electrode. The cavity structure encapsulates at least one interdigital transducer electrode. Forming the cavity structure may include forming one or more cavity walls surrounding the at least one interdigital transducer electrode and forming a cavity top supported by the cavity walls and extending over the at least one interdigital transducer electrode.

[0138] Process 700 proceeds to stage 710, in which a conductive layer is formed on a cavity structure including a cavity top and cavity walls. The conductive layer can be formed by an electroplating process. The electroplating process may include, for example, depositing a seed layer via sputtering, followed by electroplating the conductive layer onto the seed layer. The conductive layer may include sidewall portions in contact with the wafer. The conductive layer may include electrically isolated sections.

[0139] Process 700 proceeds to stage 715, where a spin-coating process is used to form an insulating layer over the conductive layer. The insulating layer may include a buffer coating. The buffer coating may include a phenolic resin and may include a rubber filler. The insulating layer may include a negative photoresist material. The insulating layer may include multiple pores exposing different portions of the conductive layer. The insulating layer may include sidewall portions that contact the wafer.

[0140] Process 700 proceeds to stage 720, in which a plurality of terminals are formed, each terminal covering and extending into a aperture in an insulating layer to contact a conductive layer. The terminals may include copper. The terminals may include a solder layer on top of the terminals.

[0141] Figure 8 This is a flowchart of a process for manufacturing a packaged surface acoustic wave (SAW) device including a piezoelectric layer with laser markings according to one embodiment. In some applications, process 800 may be performed in conjunction with process 700. Process 800 begins at stage 805, where a piezoelectric substrate supporting the packaged SAW device is provided. The packaged SAW device may include at least one interdigital transducer electrode encapsulated within a cavity structure. The packaged SAW device may include an insulating layer formed by a spin coating process. The insulating layer may include a negative photoresist, which may be a phenolic resin, and may include a rubber filler. Packaged SAW device

[0142] Process 800 proceeds to stage 810, where the piezoelectric substrate is directly laser-marked. The marking process does not increase the thickness of the packaged surface acoustic wave device because a discrete marking layer is not included. Laser marking may include using a deep UV laser to mark the piezoelectric substrate. In some examples, laser marking may involve applying a laser with a wavelength of 266 nm. Such a wavelength is suitable for marking lithium niobate and / or lithium tantalate substrates. The marked portion of the piezoelectric substrate may extend into the piezoelectric substrate to less than 1 μm.

[0143] The packaged surface acoustic wave (SAW) devices disclosed herein can be implemented in a variety of applications, such as stand-alone SAW filters in RF modules. RF modules incorporating packaged SAW devices based on any suitable principles and advantages disclosed herein may also include one or more power amplifiers, RF switches, low-noise amplifiers, inductors, etc. Such RF modules can benefit from the reduced height and / or size of the packaged SAW devices.

[0144] Figure 9 This is a schematic diagram of an RF module 900 including a surface acoustic wave (SAW) component 1076 according to one embodiment. The RF module 1200 shown includes the SAW component 1076 and other circuitry 1077. The SAW component 1076 may include one or more packaged SAW filters having any suitable combination of the features of the SAW package disclosed herein.

[0145] Figure 9 The SAW component 1076 shown includes a filter 1078 and terminals 1079A and 1079B. The filter 1078 includes a SAW resonator and can be packaged according to any suitable principles and advantages disclosed herein. Terminals 1079A and 1079B can serve as, for example, input and output contacts and can extend through a buffered resin insulating coating. Figure 9 In this configuration, SAW component 1076 and other circuitry 1077 are located on or supported by a common package substrate 1080. Package substrate 1080 may be a laminated substrate. Terminals 1079A and 1079B may be electrically connected to respective contacts 1081A and 1081B on or supported by package substrate 1080 via electrical connectors 1082A and 1082B, respectively. Electrical connectors 1082A and 1082B may be, for example, bumps or wire bonds. Other circuitry 1077 may include any suitable additional circuitry. For example, other circuitry may include one or more power amplifiers, one or more RF switches, one or more additional filters, one or more low-noise amplifiers, etc., or any suitable combination thereof. RF module 1200 may include one or more package structures to, for example, provide protection and / or facilitate disposal of RF module 1200. Such package structures may include overmolded structures formed over package substrate 1200. The encapsulation molding structure can encapsulate some or all of the components of the RF module 900.

[0146] Figure 10 This is a schematic diagram of an RF module 1000 including encapsulated surface acoustic wave components according to one embodiment. As shown, the RF module 1000 includes 1185A to 1185N duplexers having respective transmit filters 1186A1 to 1186N1 and respective receive filters 1186A2 to 1186N2, a power amplifier 1187, a selection switch 1188, and an antenna switch 1189. The RF module 1000 may include a package encapsulating the illustrated components. The illustrated components may be disposed on a common package substrate 1180. The package substrate may be, for example, a laminated substrate.

[0147] The duplexers 1185A to 1185N may each include two acoustic filters coupled to a common node. The two acoustic filters may be a transmit filter and a receive filter, and may be packaged together as discussed herein. As shown, the transmit filter and the receive filter may each be a bandpass filter configured to filter radio frequency signals. Packaged SAW devices according to any suitable principles and advantages disclosed herein may include one or more SAW resonators of one or more transmit filters 1186A1 to 1186N1 and / or one or more receive filters 1186A2 to 1186N2. Although Figure 10A duplexer is shown, but any suitable principles and advantages disclosed herein can be implemented in other multiplexers (e.g., quadplexers, sextplexers, octplexers, etc.) and / or antenna transceiver switches.

[0148] Power amplifier 1187 amplifies radio frequency (RF) signals. The switch 1188 shown is a multi-throw RF switch. Switch 1188 electrically couples the output of power amplifier 1187 to a selected transmit filter 1186A1 through 1186N1. In some examples, switch 1188 can electrically connect the output of power amplifier 1187 to more than one transmit filter 1186A1 through 1186N1. Antenna switch 1189 selectively couples signals from one or more duplexers 1185A through 1185N to the antenna port ANT. Duplexers 1185A through 1185N can be associated with different frequency bands and / or different operating modes (e.g., different power modes, different signaling modes, etc.).

[0149] Figure 11 This is a schematic block diagram of a module 1210 including a power amplifier 1212, an RF switch 1214, and duplexers 1291A to 1291N according to one or more embodiments. The power amplifier 1212 amplifies an RF signal. The RF switch 1214 may be a multi-throw RF switch. The RF switch 1214 can electrically couple the output of the power amplifier 1212 to a selected transmit filter of the duplexers 1291A to 1291N. SAW devices packaged according to any suitable principles and advantages disclosed herein may include one or more filters of the duplexers 1291A to 1291N and / or one or more SAW resonators of the duplexers 1291A to 1291N.

[0150] Figure 12This is a schematic block diagram of a module 1270 including filters 1271A to 1271N, an RF switch 1274, and a low-noise amplifier 1272 according to one embodiment. A SAW device packaged according to any suitable principles and advantages disclosed herein may include one or more SAW resonators of one or more filters 1271A to 1271N. Some or all of the filters may be packaged as discussed herein. Any suitable number of filters 1271A to 1271N can be implemented. The filters 1271A to 1271N shown are receive filters. In some embodiments (not shown), one or more filters 1271A to 1271N may be included in a multiplexer included in a transmit filter. The RF switch 1274 may be a multi-throw RF switch. The RF switch 1274 may electrically couple the output of a selected filter 1271A to 1271N to the low-noise amplifier 1272. In some embodiments (not shown), multiple low-noise amplifiers may be implemented. In some applications, module 1270 may include diversity reception features.

[0151] Figure 13 This is a schematic block diagram of module 1395, including duplexers 1391A to 1391N and antenna switch 1394. One or more filters of duplexers 1391A to 1391B can be packaged as described herein and can include any suitable number of surface acoustic wave resonators, based on any suitable principles and advantages discussed herein. Any suitable number of duplexers 1391A to 1391N can be implemented. Antenna switch 1394 may have a number of throws corresponding to the number of duplexers 1391A to 1391N. Antenna switch 1394 can electrically couple selected duplexers to the antenna port of module 1395.

[0152] Figure 14 This is a schematic diagram of a wireless communication device 1400 according to one embodiment, including a filter 1403 in an RF front-end 1402. The filter 1403 may include one or more SAW resonators according to any suitable principles and advantages discussed herein. The wireless communication device 1400 may be any suitable wireless communication device. For example, the wireless communication device 1400 may be a mobile phone, such as a smartphone. As shown, the wireless communication device 1400 may include an antenna 1401, an RF front-end 1402, a transceiver 1404, a processor 1405, a memory 1406, and a user interface 1407. The antenna 1401 may transmit RF signals provided by the RF front-end 1402. Such RF signals may include carrier aggregation signals. Although not shown, in some applications, the wireless communication device 1400 may include a microphone and a speaker.

[0153] RF front-end 1402 may include one or more power amplifiers, one or more low-noise amplifiers, one or more RF switches, one or more receive filters, one or more transmit filters, one or more duplex filters, one or more multiplexers, one or more frequency multiplexing circuits, etc., or any suitable combination thereof. RF front-end 1402 can transmit and receive RF signals associated with any suitable communication standard. Filters 1403 may be packaged with each other or with a subset of filters 1403, and may include packaged SAW devices comprising any suitable combination of features discussed with reference to any embodiments discussed herein.

[0154] Transceiver 1404 can provide RF signals to RF front-end 1402 for amplification and / or other processing. Transceiver 1404 can also process RF signals provided by the low-noise amplifier of RF front-end 1402. Transceiver 1404 communicates with processor 1405. Processor 1405 can be a baseband processor. Processor 1405 can provide any baseband processing functions suitable for wireless communication device 1400. Memory 1406 can be accessed by processor 1405. Memory 1406 can store any data suitable for wireless communication device 1400. User interface 1407 can be any suitable user interface, such as a display with touchscreen capability.

[0155] Figure 15 This is a schematic diagram of a wireless communication device 1510, including a filter 1503 in the radio frequency front-end 1502 and a second filter 1513 in the diversity reception module 1512. Except that the wireless communication device 1520 also includes diversity reception features, the wireless communication device 1510 is the same as... Figure 14 Wireless communication device 1500. For example... Figure 15 As shown, the wireless communication device 1520 includes: a diversity antenna 1511; a diversity module 1512 configured to process signals received by the diversity antenna 1511 and including a filter 1513; and a transceiver 1504 communicating with both the radio frequency front-end 1502 and the diversity receiver module 1512. The filters 1513 may be packaged with each other or with a subset of filters 1513, and may include packaged SAW devices comprising any suitable combination of features discussed with reference to any embodiments discussed herein.

[0156] Any suitable principle and advantage of the surface acoustic wave device disclosed herein can be achieved using one or more temperature-compensated SAW resonators. A temperature-compensated SAW resonator includes a temperature-compensating layer (e.g., a silicon dioxide layer) above the interdigital transducer electrodes to make the frequency temperature coefficient closer to 0.

[0157] The packaged surface acoustic wave (SAW) devices disclosed herein may include one or more SAW resonators included in a filter arranged to filter radio frequency (RF) signals in a fourth-generation (4G) Long Term Evolution (LTE) operating band. The packaged SAW devices disclosed herein may include one or more SAW resonators included in a filter arranged to filter RF signals in a fifth-generation (5G) New Radio (NR) operating band within frequency range 1 (FR1). FR1 may be, for example, from 410 MHz to 7.125 GHz, as specified in current 5G NR specifications. The packaged SAW devices disclosed herein may include one or more SAW resonators included in a filter having a passband corresponding to both the 4G LTE operating band and the 5G NR operating band within FR1.

[0158] Any of the embodiments described above can be implemented in conjunction with a radio frequency system and / or a mobile device such as a cellular phone. The principles and advantages of the embodiments can be used in any system or device that can benefit from any of the embodiments described herein. The teachings herein are applicable to a variety of systems. Although this application includes exemplary embodiments, the teachings described herein are applicable to a variety of structures. Any of the principles and advantages discussed herein can be implemented in conjunction with RF circuitry arranged to process signals in a frequency range from about 30 kHz to about 300 GHz—such as a frequency range from about 450 MHz to about 8.5 GHz.

[0159] All aspects of this application can be implemented in a variety of electronic devices. Examples of electronic devices include, but are not limited to, consumer electronics, parts of consumer electronics (such as semiconductor wafers and / or packaged radio frequency modules), electronic test equipment, uplink wireless communication devices, personal area network communication devices, etc. Examples of consumer electronics include, but are not limited to, mobile phones, such as smartphones; wearable computing devices, such as smartwatches or headsets; telephones; televisions; computer monitors, computers, routers, modems, handheld computers, laptop computers, tablet computers, personal digital assistants (PDAs), microwave ovens, refrigerators, vehicle electronic systems, such as automotive electronic systems; stereo systems, DVD players, CD players, digital music players, such as MP3 players; radios, camcorders, video cameras, such as digital cameras; portable memory chips, washing machines, dryers, washer / dryer systems, peripheral devices, clocks, etc. Furthermore, electronic devices may include unfinished products.

[0160] Unless the context explicitly requires otherwise, throughout the specification and claims, the terms “comprising,” “including,” “including,” “comprising,” etc., shall be interpreted in an inclusive sense, rather than an exclusive or exhaustive sense, that is, in the sense of “comprising (but not limited to).” The term “coupled” as generally used herein refers to two or more elements that can be directly connected or connected via one or more intermediate elements. Similarly, the term “connected” as generally used herein refers to two or more elements that can be directly connected or connected via one or more intermediate elements. Additionally, the terms “in this document,” “above,” “below,” and similar expressions used herein shall refer to the application as a whole and not to any particular part thereof. Where the context permits, singular or plural terms used in the specific embodiments may also include plural or singular terms respectively. The term “or” referring to a list of two or more items covers all of the following interpretations: any item in the list, all items in the list, or any combination of items in the list.

[0161] Furthermore, unless otherwise expressly stated or understood by the context, conditional terms such as “may,” “can,” “may,” “e.g.,” “for example,” “like,” etc., as used herein are generally intended to convey that certain embodiments do not include certain features, elements, and / or states in other embodiments. Therefore, such conditional terms are not generally intended to imply that one or more embodiments require features, elements, and / or states in any way, or that one or more embodiments must include logic for determining, with or without author input or prompting, whether such features, elements, and / or states are included or performed in any particular embodiment.

[0162] Although certain embodiments have been described, such embodiments are illustrative only and are not intended to limit the scope of this application. In fact, the novel devices, methods, and systems described herein can be embodied in various other forms; furthermore, various omissions, substitutions, and changes can be made to the methods and systems described herein without departing from the spirit of this application. For example, although blocks are presented in a given arrangement, alternative embodiments may use different elements and / or circuit topologies to perform similar functions, and some blocks may be deleted, moved, added, subdivided, combined, and / or modified. Each of such blocks can be implemented in various different ways. Any suitable combination of elements and actions of the various embodiments described above can be combined to provide further embodiments. The appended claims and their equivalents are intended to cover such forms or modifications that fall within the scope and spirit of this application.

Claims

1. A packaged surface acoustic wave device, comprising: The top of the cavity is located above the interdigital transducer electrodes of the surface acoustic wave device. A conductive structure is located above the top of the cavity; as well as A photosensitive buffer coating is placed above the conductive structure, the photosensitive buffer coating having a height of 15 micrometers or less, and the encapsulated surface acoustic wave device having a height of 220 micrometers or less.

2. The encapsulated surface acoustic wave device as described in claim 1, wherein, The encapsulated surface acoustic wave device has a height of 200 micrometers or less.

3. The encapsulated surface acoustic wave device as claimed in claim 1, further comprising: A piezoelectric substrate having a first side on which the interdigital transducer electrodes are disposed; And a cavity wall, which is on the first side of the piezoelectric substrate and supports the top of the cavity.

4. The encapsulated surface acoustic wave device as described in claim 3, wherein, The edge portion of the first side of the piezoelectric substrate does not have the photosensitive buffer coating.

5. The packaged surface acoustic wave device of claim 1, further comprising a piezoelectric substrate having a first side and a second side opposite to the first side, the interdigitated transducer electrodes being on the first side, and a marking extending into the second side, the marking extending into the piezoelectric substrate at 1 micrometer or less.

6. The surface acoustic wave device of claim 1, further comprising a terminal that is in physical contact with the conductive structure through an opening in the photosensitive buffer coating.

7. The encapsulated surface acoustic wave device as claimed in claim 1, wherein, The photosensitive buffer coating comprises phenolic resin.

8. The encapsulated surface acoustic wave device as claimed in claim 1, wherein, The photosensitive buffer coating has negative photosensitivity.

9. The encapsulated surface acoustic wave device as claimed in claim 1, wherein, The surface acoustic wave device includes a plurality of surface acoustic wave resonators arranged to filter radio frequency signals.

10. An encapsulated surface acoustic wave device, comprising: A cavity structure that is supported by a wafer and works with the wafer to encapsulate the interdigital transducer electrodes of a surface acoustic wave device. A conductive structure that extends above a portion of the outer surface of the cavity structure; as well as An insulating layer extending over the conductive structure, a portion of which covers a portion of the conductive structure, has a thickness of less than 15 micrometers, and the packaged surface acoustic wave device has a height of 220 micrometers or less.

11. The encapsulated surface acoustic wave device as claimed in claim 10, wherein, The cavity structure includes a cavity wall supported by a first surface of the wafer and a cavity top extending above the interdigital transducer electrodes and supported by the cavity wall.

12. The packaged surface acoustic wave device of claim 11, further comprising a plurality of terminals, each of the terminals extending through a portion of the insulating layer and contacting a portion of the conductive structure.

13. The encapsulated surface acoustic wave device as claimed in claim 10, wherein, The insulating layer includes a photoresist material.

14. The encapsulated surface acoustic wave device as claimed in claim 13, wherein, The insulating layer includes negative photoresist.

15. The surface acoustic wave device of claim 13, wherein, The wafer includes a laser-marked piezoelectric substrate having a first side and a second side, the first side supporting the cavity structure, and the second side of the laser-marked piezoelectric substrate having a laser-marked section.

16. An encapsulated surface acoustic wave device, comprising: Piezoelectric substrate; An encapsulation structure supported by a first surface of the piezoelectric substrate and defining a cavity, the encapsulation structure including an outer layer and a conductive layer, the outer layer including a photosensitive resin, the conductive layer being at least partially located between the cavity and the photosensitive resin; as well as Multiple interdigital transducer electrodes, supported by the piezoelectric substrate and located within the cavity, include a first interdigital transducer electrode of a first resonator and a second interdigital transducer electrode of a second resonator. The encapsulated surface acoustic wave device has a height of 220 micrometers or less, and the outer layer has a height of 15 micrometers or less.

17. The encapsulated surface acoustic wave device as claimed in claim 16, wherein, The encapsulation structure includes a cavity top and a cavity wall, both of which are located between a portion of the outer layer and the plurality of interdigital transducer electrodes.

18. The encapsulated surface acoustic wave device as claimed in claim 16, wherein, The encapsulation structure includes a conductive structure having the conductive layer that is electrically connected to at least one of the plurality of interdigital transducer electrodes.

19. The surface acoustic wave device of claim 18, wherein, The encapsulation structure includes at least one terminal that covers a portion of the outer layer and extends through the portion of the outer layer to contact the conductive structure.

20. A method of manufacturing a packaged surface acoustic wave device, the method comprising: A photosensitive resin is formed on top of a conductive structure, a portion of which is located above the cavity top above the interdigital transducer electrode of the surface acoustic wave device. as well as A conductive terminal is formed in contact with the conductive structure, at least a portion of the conductive terminal extends through a pore that extends through a portion of the photosensitive resin having a thickness of 15 micrometers or less, and the encapsulated surface acoustic wave device has a height of 220 micrometers or less.

21. The method of claim 20, further comprising: The photosensitive resin is exposed to light to develop the various parts of the photosensitive resin. And remove the unexposed portion of the photosensitive resin.

22. The method of claim 21, further comprising curing the photosensitive resin after removing the unexposed portion of the photosensitive resin.

23. The method of claim 21, wherein, Exposing a portion of the photosensitive resin to light includes: masking a portion of the photosensitive resin extending over a portion of the conductive structure to form the pores extending through the photosensitive resin.

24. The method of claim 20, wherein, Forming the terminal includes forming a conductive layer extending over the pores extending through the photosensitive resin.

25. The method of claim 20, wherein, The photosensitive resin includes phenolic resin.

26. The method of claim 20, further comprising a laser-marked piezoelectric substrate having the interdigitated transducer electrodes disposed thereon.

27. A method for manufacturing a packaged surface acoustic wave device, the method comprising: A cavity structure is formed to encapsulate the interdigital transducer electrode of a surface acoustic wave device, wherein the interdigital transducer electrode is supported by a piezoelectric substrate. A conductive structure is formed extending above each portion of the outer surface of the cavity structure; as well as A photoresist layer is formed over the conductive structure, a portion of which extends over a portion of the conductive structure and has a thickness of less than 15 micrometers. The packaged surface acoustic wave device has a height of 220 micrometers or less.

28. The method of claim 27, further comprising: The photoresist layer is patterned to form a photoresist buffer coating extending over the conductive structure and the cavity structure; And the photoresist layer is cured.

29. The method of claim 28, wherein, The photoresist buffer coating includes a portion that contacts the piezoelectric substrate and surrounds the sidewall of the cavity structure.

30. The method of claim 29, wherein, A portion of the conductive structure is in contact with the piezoelectric substrate.

31. The method of claim 27, wherein, Forming the photoresist layer over the conductive structure includes: using a spin coating process to planarize the photoresist layer.

32. The method of claim 27, further comprising removing portions of the photoresist layer within 10 micrometers of the edge of the piezoelectric substrate.

33. A method for manufacturing a packaged surface acoustic wave device, the method comprising: A cavity structure is formed extending above the interdigital transducer electrodes of the surface acoustic wave device; A conductive structure is formed extending above each portion of the outer surface of the cavity structure; as well as A photosensitive resin layer is formed over the conductive structure, a portion of which has pores extending through it and exposing a portion of the conductive structure. The encapsulated surface acoustic wave device has a height of 220 micrometers or less, and the portion of the photosensitive resin layer having the pores has a thickness of 15 micrometers or less.

34. The method of claim 33, wherein, Forming the conductive structure includes: depositing a seed layer on top of the cavity structure; and electroplating the conductive structure onto the seed layer.

35. The method of claim 34, wherein, Forming the conductive structure further includes masking portions of the seed layer before electroplating the conductive structure onto the seed layer.

36. The method of claim 33, wherein, The conductive structure includes a gap extending through a portion of the conductive structure and exposing a portion of the cavity structure, and the photosensitive resin layer fills the gap.

37. The method of claim 33, further comprising forming conductive terminals extending through pores in the photosensitive resin layer and electrically connected to the conductive structure.

38. An encapsulated surface acoustic wave device, comprising: A laser-marked piezoelectric substrate has a first side and a second side, wherein the second side of the laser-marked piezoelectric substrate has a laser-marked section, and the laser-marked section has text and number markings. as well as Interdigital transducer electrodes are encapsulated within a package structure and supported by the first side of the laser-marked piezoelectric substrate, the package structure defining a cavity enclosing the interdigital transducer electrodes.

39. The surface acoustic wave device of claim 38, wherein, The text and number markings extend less than 1 micrometer into the second side of the laser-marked piezoelectric substrate.

40. The encapsulated surface acoustic wave device as claimed in claim 38, wherein, The text and number markings extend into less than 1% of the thickness of the laser-marked piezoelectric substrate.

41. The surface acoustic wave device of claim 38, wherein, The laser marking section also includes module alignment marks.

42. The surface acoustic wave device of claim 38, wherein, The laser-marked piezoelectric substrate includes lithium niobate.

43. The surface acoustic wave device of claim 38, wherein, The laser-marked piezoelectric substrate includes lithium tantalate.

44. The surface acoustic wave device of claim 38, wherein, The encapsulation structure also includes an outer coating, which comprises a photosensitive resin.

45. The surface acoustic wave device of claim 38, wherein, The total thickness of the encapsulated surface acoustic wave device is less than 220 micrometers.

46. ​​The surface acoustic wave device of claim 38, wherein, The encapsulation structure includes a photosensitive resin buffer coating.

47. The surface acoustic wave device of claim 46, wherein, The photosensitive resin buffer coating includes phenolic resin.

48. The surface acoustic wave device of claim 46, wherein, The photosensitive resin buffer coating includes a negative photoresist.

49. The encapsulated surface acoustic wave device of claim 46, further comprising a plurality of terminals extending through pores in the photosensitive resin buffer coating.

50. An encapsulated surface acoustic wave device, comprising: A laser-marked piezoelectric substrate has a first side and a second side, wherein the second side of the laser-marked piezoelectric substrate has a laser-marked section, and the laser-marked section has text and number markings; Interdigitated transducer electrodes, which are supported by the first side of the laser-marked piezoelectric substrate; as well as The structure supported by the first side of the laser-marked piezoelectric substrate defines a cavity that encloses the interdigital transducer electrode.

51. The surface acoustic wave device of claim 50, wherein, The laser-marked section has been exposed to deep ultraviolet laser light.

52. The surface acoustic wave device of claim 50, wherein, The alphanumeric markings extend to the second side of the piezoelectric substrate by less than 1 micrometer.

53. The encapsulated surface acoustic wave device as claimed in claim 50, wherein, The laser-marked piezoelectric substrate includes lithium niobate.

54. The surface acoustic wave device of claim 50, wherein, The laser-marked piezoelectric substrate includes lithium tantalate.

55. The surface acoustic wave device of claim 50, wherein, The structure supported by the first side of the laser-marked piezoelectric substrate includes a photosensitive resin buffer coating.

56. The surface acoustic wave device of claim 55, wherein, The photosensitive resin buffer coating includes phenolic resin.

57. The surface acoustic wave device of claim 55, wherein, The photosensitive resin buffer coating includes a negative photoresist.

58. A method for marking a packaged surface acoustic wave device, the method comprising: The back side of the polished piezoelectric substrate is opposite to the front side of the piezoelectric substrate, and the interdigital transducer electrode of the surface acoustic wave device is disposed on the front side of the piezoelectric substrate. as well as The surface of the piezoelectric substrate is marked with a laser, thereby forming a mark extending into a portion of the thickness of the piezoelectric substrate, the surface defining the outer surface of the packaged surface acoustic wave device.

59. The method of claim 58, wherein, The laser marking forms a mark less than 1 micrometer extending into the piezoelectric substrate.

60. The method of claim 58, wherein, The laser marking includes: applying a laser wavelength that allows the piezoelectric substrate to maintain structural integrity.

61. The method of claim 58, wherein, The laser marking includes the use of deep ultraviolet lasers.

62. The method of claim 58, wherein, The laser marking includes using a laser with a wavelength of approximately 266 nanometers.

63. The method of claim 58, wherein, Grinding the back side of the piezoelectric substrate includes grinding the back side of the piezoelectric substrate until the thickness of the piezoelectric substrate is about 130 micrometers.

64. The method of claim 58, wherein, The piezoelectric substrate includes lithium niobate.

65. The method of claim 58, wherein, The piezoelectric substrate includes lithium tantalate.

66. The method of claim 58, further comprising forming a structure supported by the front side of the piezoelectric substrate and defining a cavity enclosing the interdigital transducer electrode.

67. The method of claim 66, wherein, The structure supported by the front side of the piezoelectric substrate is formed before the back side of the piezoelectric substrate is ground.

68. The method of claim 66, wherein, Forming the structure supported by the front side of the piezoelectric substrate includes forming a photosensitive resin buffer coating.

69. A method for marking a packaged surface acoustic wave device, the method comprising: An encapsulation structure is formed on the first surface of a piezoelectric substrate, and an interdigital transducer electrode of the surface acoustic wave device is disposed on the first surface of the piezoelectric substrate. The encapsulation structure encapsulates the interdigital transducer electrode in a cavity. as well as The second surface of the piezoelectric substrate is directly marked to form a marking portion extending into a portion of the thickness of the piezoelectric substrate, the marking portion having alphanumeric markings.

70. The method of claim 69, wherein, Directly marking the second surface of the piezoelectric substrate includes exposing the marked portion of the second surface of the piezoelectric substrate to a laser.

71. The method of claim 70, wherein, The laser includes deep ultraviolet light.

72. The method of claim 70, wherein, The laser has a wavelength of approximately 266 nanometers.

73. The method of claim 69, wherein, The encapsulation structure includes: forming a photosensitive resin layer; and patterning the photosensitive resin layer.

74. The method of claim 73, wherein, The photosensitive resin includes phenolic resin.

75. The method of claim 73, wherein, Forming an encapsulation structure may include forming conductive terminals that extend through the photosensitive resin layer.

76. The method of claim 69, wherein, The mark extends into the piezoelectric substrate by less than 1 micrometer.

77. The method of claim 69, wherein, The encapsulated surface acoustic wave device has a thickness of less than 220 micrometers.

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