HK40028069B - Bulk acoustic wave components and methods of plasma dicing the same - Google Patents

Description

Bulk acoustic wave component and method for plasma cutting of the bulk acoustic wave component

Cross-reference of priority claims

This application claims the benefit of priority to U.S. Provisional Patent Application 62/747,486, filed October 18, 2018, entitled “BULK ACOUSTIC WAVE COMPONENTS AND METHODS OF PLASMA DICING THE SAME”, the disclosure of which is incorporated herein by reference in its entirety.

Technical Field

The embodiments of this application relate to acoustic wave components, and more specifically, to bulk acoustic wave components.

Background Technology

Acoustic filters can be implemented in radio frequency (RF) electronic systems. For example, filters in the RF front-end of a mobile phone may include acoustic filters. Acoustic filters can filter RF signals. Acoustic filters can be bandpass filters. Multiple acoustic filters can be arranged as multiplexers. For example, two acoustic filters can be arranged as a duplexer.

Acoustic filters may include multiple acoustic resonators arranged to filter radio frequency signals. Example acoustic filters include surface acoustic wave (SAW) filters and bulk acoustic wave (BAW) filters. BAW filters include BAW resonators. Example BAW resonators include film bulk acoustic wave resonators (FBAR) and solidly mounted resonators (SMR). In a BAW resonator, acoustic waves propagate within the bulk of a piezoelectric layer.

BAW components may include encapsulated BAW resonators within a sealed portion. The encapsulation structure increases the size of the BAW component. There is a desire to reduce the size of the BAW component without sacrificing reliability and performance.

Summary of the Invention

Each innovation described in the claims has several aspects, and no single aspect is solely responsible for its desired properties. Without limiting the scope of the claims, some of the significant features of this application will now be briefly described.

One aspect of this application is a method for manufacturing a monolithic bulk acoustic wave (SAW) component. The method includes forming a buffer layer over a substrate of an array of SAW components to form exposed streets between the individual SAW components. The method also includes plasma-cutting the SAW components along the exposed streets to monolithize the SAW components.

Each monolithic bulk acoustic wave component may include a bulk acoustic wave resonator and a cover encapsulating the bulk acoustic wave resonator. The cover may include a sidewall 5 micrometers or less from the edge of the substrate of the respective monolithic bulk acoustic wave component. The sidewall may be at least 1 micrometer from the edge of the respective monolithic bulk acoustic wave component. The sidewall may include copper.

Plasma cutting may include etching through both the substrate and the cover substrate. Bulk acoustic wave components may include bulk acoustic wave resonators located above the substrate and below the cover substrate. The substrate and cover substrate may be silicon substrates.

The method may further include forming a conductor over a substrate. The conductor may extend laterally from a via extending through the substrate. The conductor may be electrically connected to a conductive layer in the via. A buffer layer may be formed such that the buffer layer is over at least a portion of the conductor. The method may further include forming solder over the conductor such that the solder does not overlap with the via.

The substrate may be a silicon substrate. The buffer layer may be a material that is at least 30 times slower than silicon etching during plasma cutting. The buffer layer may include a resin. Forming the buffer layer may include forming exposed blocks using a photolithography process.

Each bulk acoustic component may include a thin-film bulk acoustic resonator.

Another aspect of this application is a method for manufacturing a bulk acoustic wave (BAW) component. The method includes providing a first wafer bonded to a second wafer. The first wafer has a BAW resonator thereon. A second wafer is located above and spaced apart from the BAW resonator. The method includes forming a buffer layer on a side of the first wafer opposite to the BAW resonator, such that a block is exposed. The method includes plasma cutting through the first and second wafers along the exposed block to form a monolithic BAW component.

The first wafer and the second wafer can be silicon wafers.

Each monolithic bulk acoustic wave component may include a bulk acoustic wave resonator in a bulk acoustic wave resonator and a cover encapsulating the bulk acoustic wave resonator. The cover may include sidewalls. The sidewalls may be in the range of 1 micrometer to 5 micrometers from the edge of the substrate of the corresponding monolithic bulk acoustic wave component, wherein the substrate corresponds to a portion of a first wafer prior to plasma dicing.

Another aspect of this application is a method for manufacturing a bulk acoustic wave (BAW) component. The method includes forming a buffer layer over a silicon substrate of the BAW component, thereby exposing a block. The method further includes plasma-cutting the BAW component along the exposed block, thereby monolithizing the BAW component. Each monolithized BAW component includes a BAW resonator and a cover encapsulating the BAW resonator. The cover includes a silicon cover substrate and sidewalls spaced apart from the edge of the silicon substrate of the corresponding monolithized BAW component at distances ranging from 1 micrometer to 5 micrometers.

The sidewalls may include copper. The buffer layer may include resin. The bulk acoustic resonator may be a thin-film bulk acoustic resonator.

Another aspect of this disclosure is a bulk acoustic wave (BAW) component, comprising a substrate, at least one BAW resonator on the substrate, and a cover encapsulating the at least one BAW resonator. The cover includes sidewalls spaced apart from the edge of the substrate. The sidewalls are located 5 micrometers or less from the edge of the substrate.

The sidewalls may be 3 micrometers or less from the edge of the substrate. The sidewalls may be at least 1 micrometer from the edge of the substrate.

The bulk acoustic wave component may also include a via extending through the substrate, a conductive layer in the via, and a buffer layer in the via.

The bulk acoustic wave component may also include a via extending through the substrate, a conductor extending laterally from the via and electrically connected to a conductive layer in the via, and solder on the conductor and laterally positioned from the via.

At least one bulk acoustic wave resonator may include a thin-film bulk acoustic wave resonator. At least one bulk acoustic wave resonator may include a rigidly mounted resonator.

The substrate may be a silicon substrate. The top of the cover may include a silicon cover substrate.

The sidewalls may include copper.

The at least one bulk acoustic wave resonator may include a plurality of bulk acoustic wave resonators included in a filter, the filter being arranged to filter radio frequency signals. The plurality of bulk acoustic wave resonators may include at least 10 bulk acoustic wave resonators.

Another aspect of this application is a bulk acoustic wave (BAW) component, comprising a silicon substrate, at least one BAW resonator on the silicon substrate, and a cover encapsulating the at least one BAW resonator. The cover includes a cover substrate and sidewalls. The cover substrate is made of silicon. The sidewalls are spaced apart from the edge of the silicon substrate at a distance ranging from 1 micrometer to 5 micrometers.

The bulk acoustic wave component may also include a via extending through the silicon substrate, a conductive layer in the via, and a buffer layer in the via.

The bulk acoustic wave component may also include a via extending through the substrate, a conductor extending laterally from the via and electrically connected to a conductive layer in the via, and solder on the conductor and laterally positioned from the via.

The sidewalls may include copper. The at least one bulk acoustic resonator may include at least 10 bulk acoustic resonators included in an acoustic filter, the filter being arranged to filter radio frequency signals.

Another aspect of this application is a wireless communication device including an antenna and a bulk acoustic wave (BAW) component. The BAW component includes a substrate, a BAW resonator on the substrate, and a cover encapsulating the BAW resonator. The cover includes sidewalls spaced from the edges of the substrate at 5 micrometers or less. The BAW resonator is included in a filter communicating with the antenna.

Wireless communication devices include mobile phones.

The wireless communication device may also include a radio frequency amplifier that communicates with the filter and a switch coupled between the filter and the antenna.

In order to summarize this disclosure, certain aspects, advantages, and novel features of this application have been described herein. It should be understood that not all such advantages are necessarily achievable according to any particular embodiment. Therefore, this application may be implemented or practiced in a manner that achieves or optimizes one or more advantages taught herein, without necessarily achieving the other advantages taught or suggested herein.

Attached Figure Description

Embodiments of this disclosure will now be described with reference to the accompanying drawings and non-limiting examples.

Figure 1 is a flowchart of an example process for manufacturing a bulk acoustic component according to one embodiment.

Figures 2A to 2E are cross-sectional views illustrating the process of manufacturing a bulk acoustic component according to one embodiment.

Figure 3A is a cross-sectional view of a bulk acoustic wave component according to one embodiment.

Figure 3B is a cross-sectional view of a bulk acoustic wave component according to another embodiment.

Figure 4 is a schematic diagram of a transmission filter that includes a bulk acoustic resonator of a bulk acoustic component according to one embodiment.

Figure 5 is a schematic diagram of a receiving filter, which includes a bulk acoustic resonator of a bulk acoustic component according to one embodiment.

Figure 6 is a schematic diagram of a radio frequency system that includes a bulk acoustic wave component according to one embodiment.

Figure 7 is a schematic diagram of an RF module that includes a bulk acoustic wave component according to one embodiment.

Figure 8 is a schematic diagram of an RF module that includes a bulk acoustic wave component according to one embodiment.

Figure 9A is a schematic block diagram of a wireless communication device that includes a filter according to one or more embodiments.

Figure 9B is a schematic block diagram of another wireless communication device that includes a filter according to one or more embodiments.

Detailed Implementation

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

Acoustic filters can be used in a variety of applications, such as in the RF front-end of mobile phones, to filter radio frequency (RF) signals. Acoustic filters may include bulk acoustic wave (BAW) components. A BAW component may include a single wafer. The BAW component may include one or more BAW resonators on a substrate such as a silicon substrate. The one or more BAW resonators may be encapsulated by a cover of the BAW component. The cover may include another silicon substrate and sidewalls. The cover may form a hermetically sealed seal around the one or more BAW resonators. The sidewalls may include, for example, copper.

BAW components can be fabricated by dicing bonded wafers with hollow portions between them. Chipping occurs in a portion of the BAW component facing the hollow portion. When a large chip is present, the hermetic seal around the BAW resonator can break. To reduce and/or eliminate the risk of chipping, the BAW component may include a space between the edge of the BAW component and the sealed portion. This space may be approximately 15 to 20 micrometers from the sidewall of the cover to the diced edge of the BAW component. This space occupies an area of the BAW component.

Several aspects of this application relate to a plasma cutting method for bulk acoustic wave (BAW) components. A buffer layer can be formed over the BAW component to cover a re-wiring layer. The buffer layer can be formed such that the blocks to be cut are exposed. The buffer layer can serve as a mask layer for plasma cutting. BAW components can be monolithically processed by plasma cutting. Compared to other cutting techniques such as blade cutting or laser cutting, plasma cutting reduces the risk of breakage of BAW components. Using plasma cutting, the sidewalls of the cover housing encapsulating one or more BAW resonators can be closer to the cut edge of the BAW component without increasing the risk of breakage, compared to other cutting techniques. Plasma cutting may include cutting an upper wafer and a lower wafer across a hollow portion. The upper wafer and the lower wafer may be silicon wafers.

Plasma cutting can reduce the size of BAW components. Because the space between the cover sidewalls and the edges of the BAW components is smaller, more BAW components can be included on the wafer. Furthermore, BAW components occupy less area within the module.

Blade cutting typically produces sharp edges and can introduce lateral stress during chip cutting. This can lead to cracking and/or chipping at the sharp edges of blade-cut components. Plasma cutting, on the other hand, allows for patterning via a photolithography process used for cutting, and eliminates significant mechanical lateral stress during the process. Therefore, plasma cutting can maintain sharp edges while reducing and/or eliminating damage caused by mechanical fracture. In some cases, plasma cutting can result in smoother corners and more reliable performance in BAW components compared to mechanical fracture techniques. Rounded corners reduce and/or eliminate the risk of cracking and/or chipping in BAW components.

Using the manufacturing techniques disclosed herein, in some cases, the yield of BAW components from a single wafer can be increased by approximately 10% to 18% compared to previous manufacturing methods. This increased yield reduces manufacturing costs. Even with increased costs due to additional processing operations and/or equipment investment, the improved yield still results in lower manufacturing costs.

A method for manufacturing BAW components using plasma cutting is disclosed. Figure 1 is a flowchart of an example process 10 for manufacturing a bulk acoustic wave component according to one embodiment. Process 10 will be described with reference to the cross-sectional views illustrated in Figures 2A to 2E. Any method discussed herein may include more or fewer operations, and the operations may be performed in any appropriate order.

Process 10 includes providing one or more BAW resonators enclosed in a cover body for a substrate at frame 12. The substrate may be a silicon substrate. The cover body may include sidewalls that enclose the one or more BAW resonators together and a second substrate. The second substrate may be a silicon substrate. The one or more BAW resonators may include a film bulk acoustic wave resonator (FBAR) and/or a solidly mounted resonator (SMR).

At frame 14, a redistribution layer is formed over the substrate. The redistribution layer includes conductors extending laterally from through-substrate vias. The redistribution layer may be referred to as a wiring layer. The redistribution layer may be formed during the same processing operations as forming a conductive layer in one or more through-substrate vias of the BAW component. The redistribution layer and conductive layer may, for example, be about 5 micrometers thick. Solder may be formed over a portion of the redistribution layer. The redistribution layer provides electrical connectivity from the conductive layer in the through-substrate via to the solder in the BAW component. Using the redistribution layer, solder can be formed over any suitable portion of the substrate. For example, solder may be formed laterally from through-substrate vias. In some cases, the solder and through-substrate vias do not overlap.

Figure 2A illustrates a cross-section of multiple BAW components having a redistribution layer formed at frame 14 of process 10. As illustrated in Figure 2A, the multiple BAW components have not yet been monolithized. Figure 2A illustrates a cover substrate 21, a substrate 22, a sidewall 23, a BAW resonator 24, an air cavity 25, a through-substrate via 26, a conductive layer 27 in the respective through-substrate via 26, a redistribution layer 28, and an electrode 29. Before monolithizing individual BAW components, a first wafer includes a substrate 22 for each of the individual BAW components, and a second wafer includes a cover substrate 21 for each of the individual BAW components. As shown, the first wafer is bonded to the second wafer.

BAW resonator 24 is encapsulated within a cover body comprising a cover substrate 21 and sidewalls 23. The BAW resonator 24 is encapsulated within the cover body before the redistribution layer 28 is formed. As shown, a bonding layer 30 and a cover layer 31 may be located between the substrate 22 and the sidewalls 23. The bonding layer 30 may be a gold layer. The cover layer 31 may be a tin cover layer. This cover body forms a hermetically sealed environment around the BAW resonator 24. Therefore, an air cavity 25 may be included within the cover body surrounding the BAW resonator 24. In some cases, the BAW component may include 10 to 50 BAW resonators 24 encapsulated within the cover body. The BAW resonator 24 may include one or more FBARs. Alternatively or additionally, the BAW resonator 24 may include one or more SMRs. The BAW resonator 24 may be included in one or more filters. The substrate 21 may be a silicon substrate. The sidewalls 23 may include copper.

BAW resonators 24 are mounted on substrate 22 and encapsulated by a cover. Substrate 22 may be a silicon substrate. A conductive layer 27 in a through-hole 26 provides electrical connections from one or more BAW resonators 24 to components on the opposite side of substrate 22. As shown, a redistribution layer 28 formed at frame 14 is above substrate 22 and extends laterally from through-hole 26. Therefore, electrodes 29 can be formed laterally above redistribution layer 28 from through-hole 26. Redistribution layer 28 is on the side of substrate 22 opposite to BAW resonators 24. Electrodes 29 provide termination for external connections to BAW components. Using redistribution layer 28, electrodes 29 can be positioned at any suitable location on the BAW components. Redistribution layer 28 provides shielding. Redistribution layer 28 can shield BAW resonators 24 from external components and/or shield external components from BAW resonators 24.

Referring back to Figure 1, at box 16, a buffer layer is formed over the substrate, exposing the block. The buffer layer can be formed using a photolithography process. Forming the buffer layer may include depositing a buffer material, masking certain areas above the buffer material, and applying light to remove the buffer material above the block. The surface of the substrate may be exposed along the block. The buffer layer may provide encapsulation for the BAW component on the side opposite to the cover substrate. The buffer layer may be formed over the redistribution layer formed at box 14.

Figure 2B illustrates a cross-section of the BAW component including a buffer layer 32 formed at box 16 in process 10. The buffer layer 32 is above the substrate 22. The buffer layer 32 is on the side of the substrate 22 opposite to the BAW resonator 24. A portion of the buffer layer 32 is within a through-hole 26 in the substrate. The buffer layer 32 is also above portions of the redistribution layer 28. As shown in Figure 2B, the buffer layer 32 is formed such that the electrode 29 remains exposed. The buffer layer 32 includes a material used as a mask to resist etching during plasma dicing of the substrate 22. For example, the buffer layer 32 may be a material that is less etched than silicon when the substrate 22, which is a silicon substrate, is etched. Typically, the etch rate of the buffer layer 32 is more than 30 times slower than the etch rate of silicon. Therefore, a typical buffer layer thickness is sufficient for plasma dicing of the wafer. The buffer layer 32 may be a polyimide layer, a phenolic resin layer such as a phenolic resin layer with rubber filler, or any other suitable buffer layer. Block 34 facilitates the dicing of the BAW component.

Figure 2C illustrates an enlarged view of a portion 35 of the BAW component illustrated in Figure 2B. As shown, block 34 may have a width _DS . As shown, the width _DS is suitable for plasma cutting. The width _DS of block 34 may be in the range of about 10 micrometers to 20 micrometers, for example, in the range of 10 micrometers to 15 micrometers. As an example, the width _DS of block 34 may be about 15 micrometers. Figure 2C also illustrates that a bonding layer 30 and a capping layer 31 may be included between the substrate 22 and the sidewall 23.

Referring back to Figure 1, at box 18, the BAW component is plasma-cut along the exposed block. This monolithizes the BAW component. In other words, the BAW component is separated into individual BAW components by plasma cutting. Plasma cutting may include dry etching through the substrate on which the BAW resonator is disposed and through the cover substrate. During this etching, a hollow portion may exist between the substrate and the cover substrate below the block (e.g., as shown in Figure 2B). As an example, both the substrate and the cover substrate may be silicon substrates, which are etched at a rate of approximately 20 micrometers per minute. In this example, the substrate and the cover substrate may be approximately 200 micrometers thick together, and etching through approximately 200 micrometers of silicon may take approximately 10 minutes. Using plasma cutting reduces the fragmentation of the monolithized BAW component compared to other cutting methods such as blade cutting or laser cutting. For plasma cutting, the photolithography process can create any pattern suitable for the block. In some cases, this may result in rounded corners of the monolithized BAW component. Such rounded corners reduce the risk of BAW components cracking and/or breaking, thereby increasing the reliability of BAW components.

Figure 2D illustrates a cross-section of the BAW component after plasma cutting at box 18 in process 10. Plasma cutting along the block removes portions of the substrate 22 and the cover substrate 21, thereby separating the individual BAW components. Multiple monolithic BAW components 36 are shown in Figure 2D. Tape 37 holds the monolithic BAW components 36 together. The tape 37 can be bonded to the BAW components prior to plasma cutting.

Figure 2E illustrates an enlarged view of a portion 38 of the monolithic BAW component 36 illustrated in Figure 2D. As shown, the distance _DE from the sidewall 23 of the monolithic BAW component 36 to the edge of the substrate 22 is relatively small. Using a buffer layer as a mask for plasma cutting, a photolithography process can be used. Therefore, plasma cutting has higher precision than other cutting methods such as blade cutting or laser cutting, which have mechanical system precision. For example, plasma cutting can be performed with a precision of +/- 2 micrometers. However, in the case of blade cutting, the mechanical precision is +/- 10 micrometers, and there may be 5 to 10 micrometers of chipping. For plasma cutting, as the precision increases and the risk of chipping decreases, the distance _DE from the sidewall 23 of the monolithic BAW component 36 to the edge of the substrate 22 can be reduced. The distance _DE from the sidewall 23 of the monolithic BAW component 36 to the edge of the substrate 22 can be less than 5 micrometers. The distance _DE can be less than 3 micrometers. As an example, the distance _DE can be about 2.5 micrometers. As shown, the distance _DE is greater than zero. In some cases, the distance between _DE can be in the range of 1 micrometer to 5 micrometers, for example, in the range of 1 micrometer to 3 micrometers. In some cases, the edges of the sidewall 23 and the substrate 22 can be substantially flush in a monolithic BAW component.

Therefore, using plasma dicing, the space between the sidewalls 23 of adjacent BAW components on the wafer can be relatively small. The distance D _SW from the sidewall 23 of each adjacent monolithic BAW component corresponds to the sum of the block width _DS and the distance _DE in Figure 2E. The distance D _SW can, for example, range from about 10 micrometers to 30 micrometers. In some cases, the distance D _SW can range from about 10 micrometers to 20 micrometers. For example, the block width _DS can be about 15 micrometers and the distance _DE can be about 2.5 micrometers, which would make the distance D _SW about 20 micrometers in the cross-section illustrated in Figure 2E.

Figure 3A is a cross-sectional view of a bulk acoustic wave (BAW) component 40 according to one embodiment. The BAW component 40 can be manufactured by a process including plasma cutting. For example, the BAW component 40 can correspond to a monolithic BAW component manufactured by process 10 of Figure 1.

As shown in Figure 3A, as a result of plasma cutting, the distance _DE from the sidewall 23 to the edge of the substrate 22 of the monolithic BAW component 36 can be relatively small. The distance _DE can be within any range disclosed herein and/or have any value disclosed herein, such as the range and values described with reference to Figure 2E. In the illustrated BAW component 40, a BAW resonator 24 is encapsulated within a cover body comprising a cover substrate 21 and sidewall 23. The BAW resonator 24 may form some or all of the resonators of one or more acoustic wave filters. Any suitable number of BAW resonators 24 may be encapsulated within the cover body of the BAW component 40. For example, 10 to 50 BAW resonators 24 may be encapsulated within the cover body of the BAW component 40. The BAW resonator 24 may be electrically connected to the electrode 29 by means of a conductive layer 27 and a redistribution layer 28 in a through-substrate via 26. A buffer layer 32 extends over the redistribution layer 28 and is included in the through-substrate via 26 in the BAW component.

Figure 3B is a cross-sectional view of a bulk acoustic wave (BAW) component 42 according to one embodiment. The BAW component 42 can be manufactured using a process including plasma cutting. For example, the BAW component 42 may correspond to a monolithic BAW component manufactured by process 10 of Figure 1. The BAW component 42 is identical to the BAW component 40 of Figure 3A except that it includes a through-hole 26, wherein the through-hole 26 is filled with a conformal conductive layer 43 instead of a conductive layer 27. The conformal conductive layer 43 may be, for example, a copper layer. The BAW component 42 is illustrated with the through-hole 26 being filled with the conformal layer 43.

One or more bulk acoustic resonators of any suitable combination of features disclosed herein are included in a filter arranged to filter radio frequency signals in the fifth-generation (5G) New Radio (NR) operating band within Frequency Range 1 (FR1). The filter arranged to filter radio frequency signals in the 5G NR operating band may include one or more acoustic resonators of any bulk acoustic component disclosed herein. For example, as specified in current 5G NR specifications, FR1 may be from 410 MHz to 7.125 GHz. One or more bulk acoustic resonators of any suitable principle and advantage disclosed herein may be included in a filter arranged to filter radio frequency signals in a fourth-generation (4G) Long Term Evolution (LTE) operating band and/or have a passband spanning at least one 4G LTE operating band and at least one 5G NR operating band.

Figure 4 is a schematic diagram of a transmit filter 45, which includes a bulk acoustic wave resonator of a bulk acoustic wave component according to one embodiment. The transmit filter 45 may be a bandpass filter. The illustrated transmit filter 45 is arranged to filter the radio frequency signal received at the transmit port TX and provide the filtered output signal to the antenna port ANT. The transmit filter 45 includes series BAW resonators TS1, TS2, TS3, TS4, TS5, TS6, and TS7, parallel BAW resonators TP1, TP2, TP3, TP4, and TP5, a series input inductor L1, and a parallel inductor L2. Some or all of the BAW resonators TS1 to TS7 and/or TP1 to TP5 may be included in a BAW component according to any suitable principles and advantages disclosed herein. For example, BAW component 40 of Figure 3A or BAW component 42 of Figure 3B may include all the BAW resonators of the transmit filter 45. In some cases, a BAW component according to any suitable principles and advantages disclosed herein may include BAW resonators of two or more acoustic wave filters. The transmitting filter 45 may include any suitable number of series BAW resonators and parallel BAW resonators.

Figure 5 is a schematic diagram of a receiver filter 50, which includes a bulk acoustic wave (BAW) resonator of a BAW component according to one embodiment. The receiver filter 50 may be a bandpass filter. The illustrated receiver filter 50 is arranged to filter the radio frequency signal received at the antenna port ANT and provide the filtered output signal to the receiver port RX. The receiver filter 50 includes series BAW resonators RS1, RS2, RS3, RS4, RS5, RS6, RS7, and RS8; parallel BAW resonators RP1, RP2, RP3, RP4, RP5, and RP6; a parallel inductor L2; and a series output inductor L3. Some or all of the BAW resonators RS1 to RS8 and/or RP1 to RP6 may be included in a BAW component according to any suitable principles and advantages disclosed herein. For example, BAW component 40 of Figure 3A or BAW component 42 of Figure 3B may include all the BAW resonators of the receiver filter 50. Any suitable number of series and parallel BAW resonators may be included in the receiver filter 50.

Figure 6 is a schematic diagram of an RF system 60, which includes a bulk acoustic wave (BAW) component according to one embodiment. As shown, the RF system 60 includes an antenna 62, an antenna switch 64, multiplexers 65 and 66, filters 67 and 68, power amplifiers 70, 72, and 74, and a selection switch 73. Power amplifiers 70, 72, and 74 are respectively arranged to amplify RF signals. The selection switch 73 can electrically connect the output of power amplifier 72 to a selected filter. One or more filters of multiplexers 65 and/or 66 may include one or more BAW resonators of BAW components according to any suitable principles and advantages discussed herein. In some cases, the BAW component may include one or more filters of a multiplexer. Although the multiplexers illustrated in Figure 6 include quadduplexers and duplexers, one or more BAW resonators of the BAW component may be included in any other suitable multiplexer such as a tripplexer, sextplexer, octplexer, etc. The antenna switch can selectively electrically connect one or more filters and/or one or more multiplexers to the antenna 62.

The BAW components discussed herein can be implemented in various package modules. These BAW components consume less area in the package module compared to similar modules cut using laser cutting. A package module configured to process radio frequency signals may be referred to as a radio frequency module. Some radio frequency modules are front-end modules. A radio frequency module including any suitable principles and advantages of the BAW components disclosed herein may also include one or more radio frequency amplifiers (e.g., one or more power amplifiers and/or one or more low-noise amplifiers), one or more radio frequency switches, etc., or any suitable combination thereof. Example package modules will now be discussed in which any suitable principles and advantages of the BAW components discussed herein can be implemented. Figures 7 and 8 are schematic block diagrams of illustrative package modules according to certain embodiments. Any suitable combination of features of these embodiments may be combined with each other.

Figure 7 is a schematic diagram of an RF module 75, which includes a bulk acoustic wave (BAW) component 76 according to one embodiment. The illustrated RF module 75 includes a BAW component 76 and other circuitry 77. The BAW component 76 may include any suitable combination of the features of the BAW components disclosed herein. The BAW component 76 may include a BAW chip that includes a BAW resonator.

The BAW component 76 shown in Figure 7 includes a filter 78 and terminals 79A and 79B. The filter 78 includes a BAW resonator. Terminals 79A and 79B can be used as, for example, input and output contacts. The BAW component 76 and other circuitry 77 are on a common package substrate 80 in Figure 7. The package substrate 80 can be a laminated substrate. Terminals 79A and 79B can be electrically connected to contacts 81A and 81B on the package substrate 80, respectively, via electrical connectors 82A and 82B. Electrical connectors 82A and 82B can be, for example, bumps or wire bonds. Other circuitry 77 can include any suitable additional circuitry. For example, other circuitry can 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. The RF module 75 can include one or more package structures to, for example, provide protection for the RF module 75 and/or facilitate easier operation of the RF module 75. Such package structures can include overmold structures formed over the package substrate 75. The overmolded structure can cover some or all of the components of the RF module 75.

Figure 8 is a schematic diagram of an RF module 84, which includes a bulk acoustic wave component according to one embodiment. As shown, the RF module 84 includes duplexers 85A to 85N, each including respective transmit filters 86A1 to 86N1 and respective receive filters 86A2 to 86N2, a power amplifier 87, a selection switch 88, and an antenna switch 89. The RF module 84 may include a package encapsulating the illustrated components. The illustrated components may be disposed on a common package substrate 80. The package substrate may be, for example, a laminated substrate.

Each duplexer 85A to 85N may include two acoustic filters coupled to a common node. The two acoustic filters may be a transmit filter and a receive filter. As shown, the transmit filter and the receive filter may each be a bandpass filter configured to filter radio frequency signals. One or more of the transmit filters 86A1 to 86N1 may include one or more BAW resonators of BAW components according to any suitable principles and advantages disclosed herein. Similarly, one or more of the receive filters 86A2 to 86N2 may include one or more BAW resonators of BAW components according to any suitable principles and advantages disclosed herein. Although Figure 8 illustrates a duplexer, any suitable principles and advantages disclosed herein may be implemented in other multiplexers (e.g., quadplexers, sextplexers, octplexers, etc.) and/or switching multiplexers.

Power amplifier 87 amplifies radio frequency signals. The illustrated switch 88 is a multi-throw radio frequency switch. Switch 88 electrically couples the output of power amplifier 87 to a selected transmit filter among transmit filters 86A1 to 86N1. In some cases, switch 88 can electrically connect the output of power amplifier 87 to more than one of transmit filters 86A1 to 86N1. Antenna switch 89 selectively couples signals from one or more duplexers 85A to 85N to the antenna port ANT. Duplexers 85A to 85N can be associated with different frequency bands and/or different operating modes (e.g., different power modes, different signaling modes, etc.).

Figure 9A is a schematic diagram of a wireless communication device 90, which includes a filter 93 in an RF front-end 92 according to one embodiment. The filter 93 may include a BAW resonator of a BAW component according to any suitable principles and advantages discussed herein. The wireless communication device 90 can be any suitable wireless communication device. For example, the wireless communication device 90 may be a mobile phone such as a smartphone. As shown, the wireless communication device 90 includes an antenna 91, an RF front-end 92, a transceiver 94, a processor 95, a memory 96, and a user interface 97. The antenna 91 may transmit RF signals provided by the RF front-end 92. Such RF signals may include carrier aggregation signals.

RF front-end 92 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 92 may transmit and receive RF signals associated with any suitable communication standard. Filter 93 may include a BAW resonator of a BAW component, which includes any suitable combination of the features discussed with reference to any of the embodiments discussed above.

Transceiver 94 provides RF signals to RF front-end 92 for amplification and/or other processing. Transceiver 94 also processes RF signals provided by the low-noise amplifier of RF front-end 92. Transceiver 94 communicates with processor 95. Processor 95 may be a baseband processor. Processor 95 may provide any suitable baseband processing functions for wireless communication device 90. Memory 96 is accessible by processor 95. Memory 96 may store any suitable data for wireless communication device 90. User interface 97 may be any suitable user interface, such as a display with touchscreen functionality.

Figure 9B is a schematic diagram of a wireless communication device 100, which includes a filter 93 in a radio frequency front-end 92 and a second filter 103 in a diversity receiver module 102. Except that the wireless communication device 100 also includes diversity receiving features, the wireless communication device 100 is identical to the wireless communication device 90 of Figure 9A. As illustrated in Figure 9B, the wireless communication device 100 includes a diversity antenna 101, a diversity module 102 configured to process signals received by the diversity antenna 101 and including a filter 103, and a transceiver 104 communicating with both the radio frequency front-end 92 and the diversity receiver module 102. The filter 103 may include a BAW resonator of a BAW component, which includes any suitable combination of features discussed with reference to any of the embodiments discussed above.

Any of the above embodiments can be implemented in association with 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, such as any uplink cellular device. The teachings herein can be applied to a variety of systems. Although this disclosure includes some exemplary embodiments, the teachings described herein can be applied to a variety of architectures. Any of the principles and advantages discussed herein can be implemented in association with RF circuitry configured to process signals having frequencies in the range of about 30 kHz to 300 GHz (such as frequencies in the range of about 450 MHz to 8.5 GHz).

Various aspects of this disclosure can be implemented in a wide range of electronic devices. Examples of electronic devices include, but are not limited to, consumer electronics, components of consumer electronics such as chips and/or acoustic filter assemblies and/or packaged radio frequency modules, uplink wireless communication devices, wireless communication infrastructure, electronic test equipment, etc. Examples of electronic devices include, but are not limited to, mobile phones such as smartphones, wearable computing devices such as smartwatches or headphones, telephones, televisions, computer monitors, computers, modems, handheld computers, laptop computers, tablet computers, personal digital assistants (PDAs), microwave ovens, refrigerators, automobiles, stereo systems, DVD players, CD players, digital music players such as MP3 players, radios, portable video cameras, cameras, digital cameras, portable storage chips, washing machines, dryers, washer/dryer units, copiers, fax machines, scanners, multifunction peripherals, wristwatches, clocks, etc. Furthermore, electronic devices may include unfinished products.

Unless the context clearly requires otherwise, throughout the specification and claims, the words “comprising,” “including,” “including,” “comprising,” etc., shall be interpreted in an inclusive rather than exclusive or exhaustive sense; that is, in the sense of “including but not limited to.” As commonly used herein, the word “coupled” refers to two or more elements that can be directly connected or connected by means of one or more intermediate elements. Similarly, as commonly used herein, the word “connected” refers to two or more elements that can be directly connected or connected by means of one or more intermediate elements. Furthermore, when used in this application, the words “this,” “above,” “below,” and similar terms shall refer to this application as a whole, and not to any particular part of this application. Where the context permits, singular or plural words used in the above detailed description may also include plural or singular, respectively. The word “or” refers to a list of two or more items, and the word encompasses all the following interpretations of the word: any item in the list, all items in the list, and any combination of items in the list.

Furthermore, the conditional language used herein, such as “may,” “can,” “may,” “perhaps,” “e.g.,” “for example,” “such as,” etc., unless otherwise specifically stated or otherwise understood in the context in which they are used, is generally intended to convey that certain embodiments include certain features, elements, and/or states while other embodiments do not. Therefore, such conditional language is generally not intended to imply that one or more embodiments require features, elements, and/or states in any way.

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

Claims (37)

1. A method for manufacturing a monolithic acoustic wave component, the method comprising: A buffer layer is formed above a substrate of an array of bulk acoustic wave components to create exposed blocks between the individual bulk acoustic wave components; the substrate is a silicon substrate; and The bulk acoustic wave component is plasma-cut along the exposed block to monolithize it, and the buffer layer has an etching rate at least 30 times slower than the silicon etching rate during the plasma cutting. 2. The method of claim 1, wherein each of the monolithic bulk acoustic wave components includes a bulk acoustic wave resonator and a cover encapsulating the bulk acoustic wave resonator, and the cover includes a sidewall of 5 micrometers or less from the edge of the substrate of the respective monolithic bulk acoustic wave component. 3. The method according to claim 2, wherein the sidewall is at least 1 micrometer away from the edge of the corresponding monolithic acoustic component. 4. The method of claim 2, wherein the sidewall comprises copper. 5. The method of claim 1, wherein the plasma cutting comprises etching through both the substrate and the cover substrate, and each of the monolithic bulk acoustic wave components includes a bulk acoustic wave resonator located above the substrate and below the cover substrate. 6. The method according to claim 5, wherein the cover substrate is a silicon substrate. 7. The method of claim 1, further comprising forming a conductor over the substrate, the conductor extending laterally from a through-hole extending through the substrate, and the conductor being electrically connected to a conductive layer in the through-hole. 8. The method of claim 7, wherein the formation of the buffer layer is performed such that the buffer layer is over at least a portion of the conductor. 9. The method of claim 7, further comprising forming solder over the conductor such that the solder does not overlap with the through-hole. 10. The method of claim 1, wherein forming the buffer layer comprises forming the exposed block by means of a photolithography process. 11. The method of claim 1, wherein each of the bulk acoustic components comprises a thin-film bulk acoustic resonator. 12. A method for manufacturing a bulk acoustic component, the method comprising: A first wafer is provided bonded to a second wafer, the first wafer having a bulk acoustic wave resonator thereon, and the second wafer being above and spaced apart from the bulk acoustic wave resonator, the first wafer being a silicon wafer; A buffer layer is formed on the side of the first wafer opposite to the bulk acoustic resonator, exposing the street block; and Along the exposed block, plasma cutting is performed through the first wafer and the second wafer to form a monolithic bulk acoustic component, wherein the buffer layer has an etching rate at least 30 times slower than the silicon etching rate during the plasma cutting. 13. The method of claim 12, wherein the second wafer is a silicon wafer. 14. The method of claim 12, wherein each of the monolithic bulk acoustic wave components includes a bulk acoustic wave resonator in the bulk acoustic wave resonator and a cover enclosing the bulk acoustic wave resonator, the cover including sidewalls. 15. The method of claim 14, wherein the sidewall is located in the range of 1 micrometer to 5 micrometers from the edge of the substrate of the corresponding monolithic acoustic component, the substrate corresponding to a portion of the first wafer prior to plasma dicing. 16. A method for manufacturing a bulk acoustic component, the method comprising: A buffer layer is formed above the silicon substrate of the bulk acoustic wave component, allowing the street block to be exposed; and The bulk acoustic wave (BAW) components are monolithically cut along the exposed block area using plasma cutting. Each monolithically cut BAW component includes a BAW resonator and a cover encapsulating the BAW resonator. The cover includes a silicon cover substrate and sidewalls spaced apart from the edge of the silicon substrate of the corresponding monolithically cut BAW component at a distance ranging from 1 micrometer to 5 micrometers. 17. The method of claim 16, wherein the sidewall comprises copper and the buffer layer comprises resin. 18. The method of claim 16, wherein the bulk acoustic resonator is a thin-film bulk acoustic resonator. 19. A bulk acoustic wave component, comprising: The substrate is a silicon substrate; At least one bulk acoustic resonator on the substrate; A buffer layer, located on the side of the substrate opposite to the bulk acoustic resonator, the buffer layer comprising a material having an etching rate at least 30 times slower than the silicon etching rate; and A cover encapsulating the at least one bulk acoustic resonator, the cover including sidewalls spaced apart from the edge of the substrate, the sidewalls being 5 micrometers or less from the edge of the substrate. 20. The bulk acoustic wave component of claim 19, wherein the sidewall is 3 micrometers or less from the edge of the substrate. 21. The bulk acoustic wave component of claim 19, wherein the sidewall is at least 1 micrometer from the edge of the substrate. 22. The bulk acoustic wave component of claim 19, further comprising a through-hole extending through the substrate and a conductive layer therein, a portion of the buffer layer being in the through-hole. 23. The bulk acoustic wave component of claim 19, further comprising a through-hole extending through the substrate, a conductor extending laterally from the through-hole and electrically connected to a conductive layer in the through-hole, and solder on the conductor and laterally positioned from the through-hole. 24. The bulk acoustic wave component of claim 19, wherein the at least one bulk acoustic wave resonator comprises a thin-film bulk acoustic wave resonator. 25. The bulk acoustic wave component of claim 19, wherein the at least one bulk acoustic wave resonator comprises a rigidly mounted resonator. 26. The bulk acoustic wave component of claim 19, wherein the top of the cover comprises a silicon cover substrate. 27. The bulk acoustic wave component of claim 19, wherein the sidewall comprises copper. 28. The bulk acoustic wave component of claim 19, wherein the at least one bulk acoustic wave resonator comprises a plurality of bulk acoustic wave resonators included in a filter, the filter being arranged to filter radio frequency signals. 29. The bulk acoustic wave component according to claim 28, wherein the plurality of bulk acoustic wave resonators comprises at least 10 bulk acoustic wave resonators. 30. A bulk acoustic wave component, comprising: Silicon substrate; At least one bulk acoustic resonator on the silicon substrate; A buffer layer, located on the side of the silicon substrate opposite to the bulk acoustic wave resonator, the buffer layer comprising a material having an etching rate at least 30 times slower than the silicon etching rate; and A cover encapsulating the at least one bulk acoustic resonator, the cover comprising a cover substrate and sidewalls, the cover substrate comprising silicon, the sidewalls being spaced apart from the edge of the silicon substrate at a distance ranging from 1 micrometer to 5 micrometers. 31. The bulk acoustic wave component of claim 30, further comprising a via extending through the silicon substrate and a conductive layer therein, a portion of the buffer layer being in the via. 32. The bulk acoustic wave component of claim 30 further includes a via extending through the silicon substrate, a conductor extending laterally from the via and electrically connected to a conductive layer in the via, and solder on the conductor and laterally positioned relative to the via. 33. The bulk acoustic wave component of claim 30, wherein the sidewall comprises copper. 34. The bulk acoustic wave component of claim 30, wherein the at least one bulk acoustic wave resonator comprises at least 10 bulk acoustic wave resonators included in an acoustic wave filter, the filter being arranged to filter radio frequency signals. 35. A wireless communication device, comprising: Antenna; and A bulk acoustic wave (BAW) component includes a silicon substrate, a BAW resonator on the silicon substrate, a buffer layer located on the side of the silicon substrate opposite to the BAW resonator, and a cover encapsulating the BAW resonator. The buffer layer comprises a material having an etching rate at least 30 times slower than the silicon etching rate. The cover comprises sidewalls spaced 5 micrometers or less from the edge of the silicon substrate, and the BAW resonator is included in a filter communicating with the antenna. 36. The wireless communication device of claim 35, wherein the wireless communication device is configured as a mobile phone. 37. The wireless communication device of claim 35, further comprising a radio frequency amplifier communicating with the filter and a switch coupled between the filter and the antenna.