Patent Description:
Acoustic wave devices, for example, bulk acoustic wave (BAW) devices may be utilized as components of filters in radio frequency electronic systems. For instance, filters in a radio frequency front end of a mobile phone can include acoustic wave filters. Two acoustic wave filters can be arranged as a duplexer.

Document<NPL> discloses piston mode film bulk acoustic resonators (FBARs) with double raised borders. Document <CIT> discloses film bulk acoustic resonators located between cavities.

In accordance with an aspect disclosed herein, there is provided a film bulk acoustic wave resonator (FBAR) according to independent claim <NUM>.

The FBAR further comprises a top electrode disposed on a top surface of the piezoelectric film and a bottom electrode disposed on a bottom surface of the piezoelectric film, a vertical distance between the top electrode and the bottom electrode in the central region being greater than the vertical distance between the top electrode and the bottom electrode in the recessed frame regions. The FBAR further comprises raised frame regions disposed laterally on opposite sides of the recessed frame regions from the central region, the piezoelectric film extending laterally through the recessed frame regions, a thickness of the top electrode in the raised frame regions being greater than a thickness of the top electrode in the central region. An acoustic velocity in the piezoelectric film in the recessed frame regions may differ from an acoustic velocity in the piezoelectric film in the raised frame regions. The difference in acoustic velocity in the recessed frame regions and raised frame regions may create an acoustic velocity discontinuity sufficient to prevent transverse acoustic waves travelling through the piezoelectric film outside of the central region from entering the central region.

At least a portion of the piezoelectric film within the raised frame regions includes a greater concentration of defects than a concentration of defects in the piezoelectric film disposed in the central region. A portion of the piezoelectric film in the raised frame regions including the greater concentration of defects than the concentration of defects in the piezoelectric film disposed in the central region may contact the bottom electrode.

In some embodiments, a portion of the piezoelectric film in the recessed frame regions including the greater concentration of defects than the concentration of defects in the piezoelectric film disposed in the central region contacts the bottom electrode.

In some embodiments, the FBAR further comprises a layer of dielectric material conformally deposited on a top surface of the top electrode.

In some embodiments, upper surfaces of the bottom electrode in the recessed frame regions exhibit a greater degree of surface defects that the surface of the bottom electrode in the central region. Upper surfaces of the bottom electrode in the raised frame regions may exhibit a greater degree of surface defects that the surface of the bottom electrode in the central region.

In some embodiments, a radio frequency filter includes an FBAR as disclosed above. The radio frequency filter may be included in an electronics module. The electronics module may be included in an electronic device.

In accordance with another aspect, there is provided a method of forming a film bulk acoustic wave resonator (FBAR). The method comprises depositing a bottom electrode on an upper surface of a layer of dielectric material disposed over a cavity defined between the layer of dielectric material and a substrate, depositing a seed layer of piezoelectric material on an upper surface of the bottom electrode, etching one or more openings through the seed layer of piezoelectric material, etching of the one or more openings including over-etching of the seed layer in an amount sufficient to damage portions of the upper surface of the bottom electrode exposed by etching of the one or more openings, and depositing a bulk film of the piezoelectric material on an upper surface of the seed layer, on a portion of the upper surface of bottom electrode including the damaged portions, and on a portion of the upper surface of the dielectric layer, at least a portion of the piezoelectric film disposed in a central region and within the raised frame regions including a greater concentration of defects than a concentration of defects in the piezoelectric film disposed in the central region.

In some embodiments, over-etching of the seed layer causes sufficient damage to the upper surface of the bottom electrode to cause regions of the bulk film of piezoelectric material deposited over the one or more openings to exhibit a higher concentration of defects than regions of the bulk film of piezoelectric material deposited over portions of the seed layer not including the one or more openings.

The method further comprises depositing a layer of conductive material on an upper surface of the bulk film of the piezoelectric material to form a top electrode. Depositing the layer of conductive material may include depositing the layer of conductive material with a first thickness in a central region disposed between areas directly above the one or more openings in the seed layer and depositing the conductive material with a second thickness greater than the first thickness in areas on opposite sides of the areas directly above the one or more openings in the seed layer from the central region.

The method further comprises conformally depositing a layer of dielectric material on an upper surface of the layer of conductive material.

Embodiments of this disclosure will now be described, by way of non-limiting example, with reference to the accompanying drawings.

The following description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in a multitude of different ways, for example, as defined and covered by the claims. In this description, reference is made to the drawings where like reference numerals can indicate identical or functionally similar elements. It will be understood that elements illustrated in the figures are not necessarily drawn to scale. Moreover, it will be understood that certain embodiments can include more elements than illustrated in a drawing and/or a subset of the elements illustrated in a drawing. Further, some embodiments can incorporate any suitable combination of features from two or more drawings.

Film bulk acoustic wave resonators (FBARs) are a form of bulk acoustic wave resonator that generally includes a film of piezoelectric material sandwiched between a top and a bottom electrode and suspended over a cavity that allows for the film of piezoelectric material to vibrate. A signal applied across the top and bottom electrodes causes an acoustic wave to be generated in and travel through the film of piezoelectric material. A FBAR exhibits a frequency response to applied signals with a resonance peak determined by a thickness of the film of piezoelectric material. Ideally, the only acoustic wave that would be generated in a FBAR is a main acoustic wave that would travel through the film of piezoelectric material in a direction perpendicular to layers of conducting material forming the top and bottom electrodes. The piezoelectric material of a FBAR, however, typically has a non-zero Poisson's ratio. Compression and relaxation of the piezoelectric material associated with passage of the main acoustic wave may thus cause compression and relaxation of the piezoelectric material in a direction perpendicular to the direction of propagation of the main acoustic wave. The compression and relaxation of the piezoelectric material in the direction perpendicular to the direction of propagation of the main acoustic wave may generate transverse acoustic waves that travel perpendicular to the main acoustic wave (parallel to the surfaces of the electrode films) through the piezoelectric material. The transverse acoustic waves may be reflected back into an area in which the main acoustic wave propagates and may induce spurious acoustic waves travelling in the same direction as the main acoustic wave. These spurious acoustic waves may degrade the frequency response of the FBAR from what is expected or from what is intended and are generally considered undesirable.

<FIG> is cross-sectional view of an example of a FBAR, indicated generally at <NUM>. The FBAR <NUM> is disposed on a substrate <NUM>, for example, a silicon substrate that may include a dielectric surface layer 110A of, for example, silicon dioxide. The FBAR <NUM> includes a layer or film of piezoelectric material <NUM>, for example, aluminum nitride (A1N). A top electrode <NUM> is disposed on top of a portion of the layer or film of piezoelectric material <NUM> and a bottom electrode <NUM> is disposed on the bottom of a portion of the layer or film of piezoelectric material <NUM>. The top electrode <NUM> may be formed of, for example, ruthenium (Ru). The bottom electrode <NUM> may include a layer 125A of Ru disposed in contact with the bottom of the portion of the layer or film of piezoelectric material <NUM> and a layer 125B of titanium (Ti) disposed on a lower side of the layer 125A of Ru opposite a side of the layer 125A of Ru in contact with the bottom of the portion of the layer or film of piezoelectric material <NUM>. Each of the top electrode <NUM> and the bottom electrode <NUM> may be covered with a layer of dielectric material <NUM>, for example, silicon dioxide. A cavity <NUM> is defined beneath the layer of dielectric material <NUM> covering the bottom electrode <NUM> and the surface layer 110A of the substrate <NUM>. A bottom electrical contact <NUM> formed of, for example, copper may make electrical connection with the bottom electrode <NUM> and a top electrical contact <NUM> formed of, for example, copper may make electrical connection with the top electrode <NUM>.

The FBAR <NUM> may include a central region <NUM> including a main active domain in the layer or film of piezoelectric material <NUM> in which a main acoustic wave is excited during operation. The central region may have a width of, for example, between about <NUM> and about <NUM>. A recessed frame region or regions <NUM> may bound and define the lateral extent of the central region <NUM>. The recessed frame regions may have a width of, for example, about <NUM>. The recessed frame region(s) <NUM> may be defined by areas that have a thinner layer of dielectric material <NUM> on top of the top electrode <NUM> than in the central region <NUM>. The dielectric material layer <NUM> in the recessed frame region(s) <NUM> may be from about <NUM> to about <NUM> thinner than the dielectric material layer <NUM> in the central region <NUM> and/or the difference in thickness of the dielectric material in the recessed frame region(s) <NUM> vs. in the central region <NUM> may cause the resonant frequency of the device in the recessed frame region(s) <NUM> to be between about <NUM> to about <NUM> higher than the resonant frequency of the device in the central region <NUM>. A raised frame region or regions <NUM> may be defined on an opposite side of the recessed frame region(s) <NUM> from the central region <NUM> and may directly abut the outside edge(s) of the recessed frame region(s) <NUM>. The raised frame regions may have widths of, for example, about <NUM>. The raised frame region(s) <NUM> may be defined by areas where the top electrode <NUM> is thicker than in the central region <NUM> and in the recessed frame region(s) <NUM>. The top electrode <NUM> may have the same thickness in the central region <NUM> and in the recessed frame region(s) <NUM> but a greater thickness in the raised frame region(s) <NUM>. The top electrode <NUM> may be between about <NUM> and about <NUM> thicker in the raised frame region(s) <NUM> than in the central region <NUM> and/or in the recessed frame region(s) <NUM>.

The recessed frame region(s) <NUM> and the raised frame region(s) <NUM> may contribute to dissipation or scattering of transverse acoustic waves generated in the FBAR <NUM> during operation and/or may reflect transverse waves propagating outside of the recessed frame region(s) <NUM> and the raised frame region(s) <NUM> and prevent these transverse acoustic waves from entering the central region and inducing spurious signals in the main active domain region of the FBAR. Without being bound to a particular theory, it is believed that due to the thinner layer of dielectric material <NUM> on top of the top electrode <NUM> in the recessed frame region(s) <NUM>, the recessed frame region(s) <NUM> may exhibit a higher velocity of propagation of acoustic waves than the central region <NUM>. Conversely, due to the increased thickness and mass of the top electrode <NUM> in the raised frame region(s) <NUM>, the raised frame regions(s) <NUM> may exhibit a lower velocity of propagation of acoustic waves than the central region <NUM> and a lower velocity of propagation of acoustic waves than the recessed frame region(s) <NUM>. The discontinuity in acoustic wave velocity between the recessed frame region(s) <NUM> and the raised frame region(s) <NUM> creates a barrier that scatters, suppresses, and/or reflects transverse acoustic waves.

It has been recognized that the FBAR structure <NUM> illustrated in <FIG> may be improved upon. For example, during manufacturing it is sometimes difficult to precisely control etching of the layer of dielectric material <NUM> covering the top electrode <NUM> in the recessed frame region(s) <NUM>. Manufacturing variability may result in different absolute or relative thicknesses between the layer of dielectric material <NUM> covering the top electrode <NUM> in the recessed frame region(s) <NUM> as compared with layer of dielectric material <NUM> covering the top electrode <NUM> in the central region across a wafer on which FBAR structures are formed, between different wafers in a batch, or between different production runs. The behavior of the FBAR structure <NUM> illustrated in <FIG> may thus undesirably vary from device to device.

An improvement to the FBAR structure <NUM> of <FIG> that may both reduce manufacturing variability and increase the degree to which transverse acoustic waves and associated spurious signals are suppressed is illustrated in <FIG>. The FBAR <NUM> of <FIG> is substantially the same as that of <FIG> and the common features are not numbered and are not described herein in detail. A difference between the FBAR structure <NUM> of <FIG> and the FBAR structure <NUM> of <FIG> is that in the FBAR structure <NUM> of <FIG>, a region <NUM> of low-quality piezoelectric material <NUM> is intentionally formed in the recessed frame region(s) <NUM>. The region <NUM> of low-quality piezoelectric material <NUM> may include a greater concentration of defects (e.g., voids, stacking faults, dislocations, misalignment of piezoelectric material crystals, etc. than the piezoelectric material <NUM> in the central region <NUM> and raised frame region(s) <NUM>. In some embodiments, the region <NUM> of low quality piezoelectric material <NUM> may have surface roughness higher than other areas of the piezoelectric material <NUM> and/or a greater number or density of other forms of defects, for example, lattice vacancies, self-interstitial atoms, substitution or interstitial impurity atoms or other impurities, grain boundaries, alternate phases, inclusions, or mismatched crystallinity as compared to other areas of the piezoelectric material <NUM>, for example, in the central region <NUM> and/or raised frame region(s) <NUM>. The defects in the region <NUM> of low quality piezoelectric material <NUM> may create a greater degree of difference in acoustic impedance between the recessed frame region(s) <NUM> and raised frame region(s) <NUM> and/or central region <NUM> in the FBAR structure of <FIG> than between the corresponding recessed frame region(s) <NUM> and raised frame region(s) <NUM> and/or central region <NUM> in the FBAR structure <NUM> of <FIG>. The increased difference in acoustic impedance between the different regions of the FBAR <NUM> of <FIG> may suppress or refract transverse acoustic waves to a greater extent than in the FBAR <NUM> of <FIG>. The recessed frame region(s) <NUM> may also exhibit a higher acoustic velocity than the central region <NUM> and raised frame region(s) <NUM> due to the reduced overall film thickness in the recessed frame region(s) <NUM> as compared to the overall film thickness in the central region <NUM> and raised frame region(s) <NUM>. As explained further below, a seed layer <NUM> of piezoelectric material <NUM> having open areas <NUM> into which the region <NUM> of low-quality piezoelectric material <NUM> extends may facilitate forming the region <NUM> of low-quality piezoelectric material <NUM>.

In another embodiment, illustrated in <FIG>, in an FBAR structure <NUM>, a region <NUM> of low-quality piezoelectric material <NUM> similar to region <NUM> in <FIG> may extend into both the recessed frame region(s) <NUM> and partially or completely into the raised frame region(s) <NUM> on opposite sides of the central region <NUM>.

In a further embodiment, illustrated in <FIG>, in an FBAR structure <NUM>, a region <NUM> of low quality piezoelectric material <NUM> similar to region <NUM> in <FIG> may extend into both the recessed frame region(s) <NUM> and past one or each of the raised frame region(s) <NUM> on opposite sides of the central region <NUM> and partially or completely into portions of the piezoelectric material <NUM> covered by the bottom electrical contact <NUM> and/or top electrical contact <NUM>.

It should be appreciated that the FBARs illustrated in <FIG>, are illustrated in a highly simplified form. The relative dimensions of the different features are not shown to scale. Further, typical FBARs may include additional features or layers not illustrated.

Certain acts in forming embodiments of a FBAR structure including regions of low-quality piezoelectric material are illustrated in <FIG>. It should be appreciated that many other acts that are not illustrated, but that would be understood by one of ordinary skill in the art, may be involved in forming the completed FBAR structures.

In one act, illustrated in <FIG>, a bottom electrode <NUM> is deposited on a layer of dielectric material 110A formed on a substrate <NUM> and defining a cavity <NUM>. A seed layer <NUM> of piezoelectric material, for example, AlN, is deposited directly on top of the bottom electrode <NUM> and the exposed portion of dielectric material 110A. The seed layer <NUM> may be deposited by, for example, chemical vapor deposition (CVD) or atomic layer deposition (ALD) which may provide for very precise control of the thickness of the seed layer <NUM>.

After the seed layer <NUM> of piezoelectric material is deposited, open areas <NUM> are formed above which the regions of low-quality piezoelectric material will later be formed. The open areas may be positioned and dimensioned to correspond with the recessed frame region(s) <NUM> of the to-be-completed FBAR, as illustrated in <FIG> and in <FIG> (discussed further below) and/or to correspond with a portion or entirety of the raised frame regions(s) <NUM> of the to-be-completed FBAR, as illustrated in <FIG> and in <FIG> (discussed further below). In other embodiments, the seed layer <NUM> of piezoelectric material may be removed from all portions of the bottom electrode <NUM> and layer of dielectric material outside of the central region <NUM>, as illustrated in <FIG>, to form a FBAR as illustrated in <FIG>. The seed layer <NUM> of piezoelectric material may be etched by dry etching, using, for example, a plasma or ion beam. Over-etching of the seed layer <NUM> may be performed, which results in damage, for example, surface roughness, pits, or other inhomogeneities in the upper surface of the portions of the bottom electrode <NUM> that become exposed during etching of the open areas <NUM> in the seed layer <NUM> of piezoelectric material.

After the open areas <NUM> are formed in the seed layer <NUM> of piezoelectric material or portions of the seed layer <NUM> are removed, the bulk of the film of piezoelectric material <NUM> is deposited over the seed layer <NUM> and portions of the bottom electrode <NUM> and the layer of dielectric material 110A. The bulk of the film of piezoelectric material may be deposited using a similar method as was used to deposit the seed layer <NUM>, for example, CVD or ALD. The piezoelectric material deposited over the portions 125A of the bottom electrode <NUM> and/or dielectric layer 110B that were damaged by over-etching of the seed layer <NUM> may have a greater degree of defects and/or misaligned crystalline domains than in the piezoelectric material <NUM> deposited over the seed layer <NUM> and undamaged portions of the bottom electrode <NUM> and layer of dielectric material 110A. The piezoelectric material deposited over the portions of the bottom electrode <NUM> and/or dielectric material 110B that were damaged by over-etching of the seed layer <NUM> may thus include regions <NUM>, <NUM> that exhibit lower quality than the piezoelectric material deposited over the seed layer <NUM> and undamaged portions of the bottom electrode <NUM> and layer of dielectric material 110A.

Upon completion of deposition of the bulk of the film of piezoelectric material, surfaces of the portions of the film of piezoelectric material that were deposited over the open areas <NUM> in the seed layer <NUM> (regions <NUM>) or over portions of the bottom electrode <NUM> and/or layer of dielectric material 110A, 110B from which the seed layer <NUM> was removed may be recessed from surfaces of portions of the piezoelectric material deposited over the seed layer <NUM> and undamaged portions of the bottom electrode <NUM> and/or layer of dielectric material 110A. The depth of the recesses <NUM> (<FIG>) may correspond to the thickness of the seed layer <NUM>. As discussed above, the seed layer <NUM> may be deposited with a high degree of control over thickness. The depth of the recesses <NUM> may thus be more tightly controlled and less susceptible to manufacturing variability than recesses etched in the dielectric layer <NUM> in the recessed frame region(s) <NUM> in the FBAR structure <NUM> illustrated in <FIG>.

To complete the FBAR structure, a layer (or layers) of electrode material may be deposited on top of the bulk of the film of piezoelectric material illustrated in <FIG>, with thicker portions of the electrode material film being deposited in the raised frame region(s) <NUM>. A conformal layer of dielectric material <NUM> may then be deposited over the electrode material film to result in the FBAR structure illustrated in <FIG>, <FIG>.

The acoustic wave devices discussed herein can be implemented in a variety of packaged modules. Some example packaged modules will now be discussed in which any suitable principles and advantages of the packaged acoustic wave devices discussed herein can be implemented. <FIG>, <FIG> are schematic block diagrams of illustrative packaged modules and devices according to certain embodiments.

As discussed above, embodiments of the disclosed FBARs can be configured as or used in filters, for example. In turn, a FBAR filter using one or more FBAR elements may be incorporated into and packaged as a module that may ultimately be used in an electronic device, such as a wireless communications device, for example. <FIG> is a block diagram illustrating one example of a module <NUM> including a FBAR filter <NUM>. The FBAR filter <NUM> may be implemented on one or more die(s) <NUM> including one or more connection pads <NUM>. For example, the FBAR filter <NUM> may include a connection pad <NUM> that corresponds to an input contact for the FBAR filter and another connection pad <NUM> that corresponds to an output contact for the FBAR filter. The packaged module <NUM> includes a packaging substrate <NUM> that is configured to receive a plurality of components, including the die <NUM>. A plurality of connection pads <NUM> can be disposed on the packaging substrate <NUM>, and the various connection pads <NUM> of the FBAR filter die <NUM> can be connected to the connection pads <NUM> on the packaging substrate <NUM> via electrical connectors <NUM>, which can be solder bumps or wirebonds, for example, to allow for passing of various signals to and from the FBAR filter <NUM>. The module <NUM> may optionally further include other circuitry die <NUM>, such as, for example one or more additional filter(s), amplifiers, pre-filters, modulators, demodulators, down converters, and the like, as would be known to one of skill in the art of semiconductor fabrication in view of the disclosure herein. In some embodiments, the module <NUM> can also include one or more packaging structures to, for example, provide protection and facilitate easier handling of the module <NUM>. Such a packaging structure can include an overmold formed over the packaging substrate <NUM> and dimensioned to substantially encapsulate the various circuits and components thereon.

Various examples and embodiments of the FBAR filter <NUM> can be used in a wide variety of electronic devices. For example, the FBAR filter <NUM> can be used in an antenna duplexer, which itself can be incorporated into a variety of electronic devices, such as RF front-end modules and communication devices.

Referring to <FIG>, there is illustrated a block diagram of one example of a front-end module <NUM>, which may be used in an electronic device such as a wireless communications device (e.g., a mobile phone) for example. The front-end module <NUM> includes an antenna duplexer <NUM> having a common node <NUM>, an input node <NUM>, and an output node <NUM>. An antenna <NUM> is connected to the common node <NUM>.

The antenna duplexer <NUM> may include one or more transmission filters <NUM> connected between the input node <NUM> and the common node <NUM>, and one or more reception filters <NUM> connected between the common node <NUM> and the output node <NUM>. The passband(s) of the transmission filter(s) are different from the passband(s) of the reception filters. Examples of the FBAR filter <NUM> can be used to form the transmission filter(s) <NUM> and/or the reception filter(s) <NUM>. An inductor or other matching component <NUM> may be connected at the common node <NUM>.

The front-end module <NUM> further includes a transmitter circuit <NUM> connected to the input node <NUM> of the duplexer <NUM> and a receiver circuit <NUM> connected to the output node <NUM> of the duplexer <NUM>. The transmitter circuit <NUM> can generate signals for transmission via the antenna <NUM>, and the receiver circuit <NUM> can receive and process signals received via the antenna <NUM>. In some embodiments, the receiver and transmitter circuits are implemented as separate components, as shown in <FIG>, however in other embodiments these components may be integrated into a common transceiver circuit or module. As will be appreciated by those skilled in the art, the front-end module <NUM> may include other components that are not illustrated in <FIG> including, but not limited to, switches, electromagnetic couplers, amplifiers, processors, and the like.

<FIG> is a block diagram of one example of a wireless device <NUM> including the antenna duplexer <NUM> shown in <FIG>. The wireless device <NUM> can be a cellular phone, smart phone, tablet, modem, communication network or any other portable or non-portable device configured for voice or data communication. The wireless device <NUM> can receive and transmit signals from the antenna <NUM>. The wireless device includes an embodiment of a front-end module <NUM> similar to that discussed above with reference to <FIG>. The front-end module <NUM> includes the duplexer <NUM>, as discussed above. In the example shown in <FIG> the front-end module <NUM> further includes an antenna switch <NUM>, which can be configured to switch between different frequency bands or modes, such as transmit and receive modes, for example. In the example illustrated in <FIG>, the antenna switch <NUM> is positioned between the duplexer <NUM> and the antenna <NUM>; however, in other examples the duplexer <NUM> can be positioned between the antenna switch <NUM> and the antenna <NUM>. In other examples the antenna switch <NUM> and the duplexer <NUM> can be integrated into a single component.

The front-end module <NUM> includes a transceiver <NUM> that is configured to generate signals for transmission or to process received signals. The transceiver <NUM> can include the transmitter circuit <NUM>, which can be connected to the input node <NUM> of the duplexer <NUM>, and the receiver circuit <NUM>, which can be connected to the output node <NUM> of the duplexer <NUM>, as shown in the example of <FIG>.

Signals generated for transmission by the transmitter circuit <NUM> are received by a power amplifier (PA) module <NUM>, which amplifies the generated signals from the transceiver <NUM>. The power amplifier module <NUM> can include one or more power amplifiers. The power amplifier module <NUM> can be used to amplify a wide variety of RF or other frequency-band transmission signals. For example, the power amplifier module <NUM> can receive an enable signal that can be used to pulse the output of the power amplifier to aid in transmitting a wireless local area network (WLAN) signal or any other suitable pulsed signal. The power amplifier module <NUM> can be configured to amplify any of a variety of types of signal, including, for example, a Global System for Mobile (GSM) signal, a code division multiple access (CDMA) signal, a W-CDMA signal, a Long-Term Evolution (LTE) signal, or an EDGE signal. In certain embodiments, the power amplifier module <NUM> and associated components including switches and the like can be fabricated on gallium arsenide (GaAs) substrates using, for example, high-electron mobility transistors (pHEMT) or insulated-gate bipolar transistors (BiFET), or on a Silicon substrate using complementary metal-oxide semiconductor (CMOS) field effect transistors.

Still referring to <FIG>, the front-end module <NUM> may further include a low noise amplifier module <NUM>, which amplifies received signals from the antenna <NUM> and provides the amplified signals to the receiver circuit <NUM> of the transceiver <NUM>.

The wireless device <NUM> of <FIG> further includes a power management sub-system <NUM> that is connected to the transceiver <NUM> and manages the power for the operation of the wireless device <NUM>. The power management system <NUM> can also control the operation of a baseband sub-system <NUM> and various other components of the wireless device <NUM>. The power management system <NUM> can include, or can be connected to, a battery (not shown) that supplies power for the various components of the wireless device <NUM>. The power management system <NUM> can further include one or more processors or controllers that can control the transmission of signals, for example. In one embodiment, the baseband sub-system <NUM> is connected to a user interface <NUM> to facilitate various input and output of voice and/or data provided to and received from the user. The baseband sub-system <NUM> can also be connected to memory <NUM> that is configured to store data and/or instructions to facilitate the operation of the wireless device, and/or to provide storage of information for the user. Any of the embodiments described above can be implemented in association with mobile devices such as cellular handsets. The principles and advantages of the embodiments can be used for any systems or apparatus, such as any uplink wireless communication device, that could benefit from any of the embodiments described herein. The teachings herein are applicable to a variety of systems. Although this disclosure includes some example embodiments, the teachings described herein can be applied to a variety of structures. Any of the principles and advantages discussed herein can be implemented in association with RF circuits configured to process signals in a range from about <NUM> to <NUM>, such as in a range from about <NUM> to <NUM>.

Aspects of this disclosure can be implemented in various electronic devices. Examples of the electronic devices can include, but are not limited to, consumer electronic products, parts of the consumer electronic products such as packaged radio frequency modules, uplink wireless communication devices, wireless communication infrastructure, electronic test equipment, etc. Examples of the electronic devices can include, but are not limited to, a mobile phone such as a smart phone, a wearable computing device such as a smart watch or an ear piece, a telephone, a television, a computer monitor, a computer, a modem, a hand-held computer, a laptop computer, a tablet computer, a microwave, a refrigerator, a vehicular electronics system such as an automotive electronics system, a stereo system, a digital music player, a radio, a camera such as a digital camera, a portable memory chip, a washer, a dryer, a washer/dryer, a copier, a facsimile machine, a scanner, a multi-functional peripheral device, a wrist watch, a clock, etc. Further, the electronic devices can include unfinished products.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," "include," "including" and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to. " The word "coupled", as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Likewise, the word "connected", as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word "or" in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

Moreover, conditional language used herein, such as, among others, "can," "could," "might," "may," "e.g.," "for example," "such as" and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or states are included or are to be performed in any particular embodiment.

Claim 1:
A film bulk acoustic wave resonator, FBAR, (<NUM>; <NUM>) comprising:
a piezoelectric film (<NUM>) disposed in a central region (<NUM>) defining a main active domain in which a main acoustic wave is generated during operation, in recessed frame regions (<NUM>) disposed laterally on opposite sides of the central region (<NUM>), and in raised frame regions (<NUM>) disposed laterally on opposite sides of the recessed frame regions (<NUM>) from the central region (<NUM>), the piezoelectric film (<NUM>) disposed in the recessed frame regions (<NUM>) and at least a portion of the piezoelectric film (<NUM>) disposed within the raised frame regions (<NUM>) including a greater concentration of defects than a concentration of defects in the piezoelectric film (<NUM>) disposed in the central region (<NUM>);
a top electrode (<NUM>) disposed on a top surface of the piezoelectric film (<NUM>), the piezoelectric film (<NUM>) extending laterally through the recessed frame regions (<NUM>), a thickness of the top electrode (<NUM>) in the raised frame regions (<NUM>) being greater than a thickness of the top electrode (<NUM>) in the central region (<NUM>); and
a bottom electrode (<NUM>) disposed on a bottom surface of the piezoelectric film (<NUM>), a vertical distance between the top electrode (<NUM>) and the bottom electrode (<NUM>) in the central region (<NUM>) being greater than the vertical distance between the top electrode (<NUM>) and the bottom electrode (<NUM>) in the recessed frame regions (<NUM>).