Electrode defined resonator

Abstract

To provide a bulk acoustic resonator comprising a resonator body and one or more connecting structures that make it possible to supply electrical signals to one or more conductive layers of the resonator body.SOLUTION: A bulk acoustic resonator operable in a bulk acoustic mode includes a resonator body 4 mounted on a separate carrier 14 that is not part of the resonator body 4. The resonator body 4 includes a piezoelectric layer 8, a device layer 12, and a top conductive layer 6 on the piezoelectric layer opposite the device layer. A surface of the device layer opposite the piezoelectric layer is for mounting the resonator body on the carrier.SELECTED DRAWING: Figure 1

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 699,078, filed July 17, 2018, and entitled "Electrode Defined Resonator," the contents of which are incorporated herein by reference. [Background technology]

[0002] FIELD OF THEINVENTION The present invention relates to bulk acoustic resonators, and more particularly to bulk acoustic resonators having a resonator body and, optionally, one or more connection structures that can be used to provide an electrical signal to one or more conductive layers of the resonator body.

[0003] 2. Description of Related Art Radio frequency communications has evolved from "1G" systems in the 1980s, to "2G" systems in the 1990s, to "3G" systems in the early 2000s, to the current "4G" systems standardized in 2012. In current RF communications, RF signals are filtered using surface acoustic wave (SAW) filters or bulk acoustic wave (BAW) filters.

[0004] Film-bulk-acoustic-resonators (FBAR) and solid-mounted-resonators (SMR) are two types of BAW filters that are piezoelectrically actuated microelectromechanical system (MEMS) elements that enable current 4G RF communications to resonate at relatively high frequencies with relatively low insertion loss compared to SAW filter elements. These BAW acoustic resonators, in one example, comprise a piezoelectric stack that includes a thin film of piezoelectric material sandwiched between a thin film top electrode and a thin film bottom electrode. The resonant frequency of such a piezoelectric stack is thickness-based, or depends on the thickness of the thin film of the piezoelectric stack. The resonant frequency increases as the thickness of the thin film of the piezoelectric stack decreases. The film thickness of the resonator is critical and must be precisely controlled for the desired resonant frequency. To achieve reasonable yields of FBAR and SMR manufacturing processes for a targeted or specified RF frequency, it is difficult and time-consuming to adjust different regions of the piezoelectric stack to achieve a high level of thickness uniformity.

[0005] The 5G RF communications systems being developed will eventually replace the lower performance older generation communications systems mentioned above that operate at RF frequencies between a few hundred MHz and 1.8 GHz. 5G systems will instead operate at much higher RF frequencies, e.g., 3 to 6 GHz (less than 6 GHz), and in some cases up to around 100 GHz.

[0006] Due to this increase in frequency, the film thickness of FBAR and SMR-based RF filters for 5G applications will have to be reduced to increase the resonant frequency, which is one of the challenges facing current state-of-the-art BAW acoustic resonators. Reducing the piezoelectric film thickness means that the distance between the top and bottom electrodes of the piezoelectric stack is also reduced, resulting in an increase in capacitance. This increase in capacitance results in higher feedthrough of the RF signal, reducing the signal-to-noise ratio, which is undesirable. The optimal piezoelectric coupling efficiency of the piezoelectric stack (including the top electrode, the bottom electrode, and the piezoelectric layer sandwiched between the top and bottom electrodes) can result from a proper combination of the thickness of the piezoelectric layer, the thickness of the top electrode, the thickness of the bottom electrode, and the alignment and orientation of the piezoelectric crystals. Reducing the piezoelectric film thickness to achieve the desired high RF frequency operation for 5G communication may not allow the achievement of optimal piezoelectric coupling efficiency, which results in higher insertion loss and higher motional impedance. The thickness of either the top electrode, the bottom electrode, or both electrodes may also need to be reduced. A reduction in electrode thickness leads to an increase in electrical resistivity, which results in another undesirable limitation, namely higher insertion loss.

[0007] Furthermore, the product of frequency and quality factor (or Q) of FBAR and SMR elements is typically constant, which means that an increase in resonant frequency results in a decrease in Q. A decrease in Q is undesirable, especially given that the highest levels of Q for FBARs and SMRs approach theoretical limits at frequencies below 2.45 GHz. Thus, doubling the frequency results in a decrease in Q, which is undesirable for fabricating RF elements such as RF filters, RF resonators, RF switches, and RF oscillators. Summary of the Invention

[0008] A resonator body is provided that can operate generally in a bulk acoustic mode, and preferentially in a transverse resonance mode. A bottom surface of the resonator body can be mounted or coupled to a mounting substrate or carrier while still allowing use of the resonator body as an RF filter, RF resonator, RF switch, RF oscillator, or the like.

[0009] Also provided is a bulk acoustic resonator including a resonator body and one or more connection structures that allow an electrical signal to be provided to one or more conductive layers of the resonator body. In one preferred and non-limiting embodiment or example, the one or more connection structures can be integral with and / or formed from the same layer of material as the resonator body, such that the bulk acoustic resonator can be a one-piece piece. A bottom surface of the one-piece bulk acoustic resonator can be mounted or bonded to a mounting substrate or carrier while still allowing use of the resonator body as an RF filter, RF resonator, RF switch, RF oscillator, etc.

[0010] These and other features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a side view of one preferred and non-limiting embodiment or example of a non-suspended bulk acoustic resonator in accordance with the principles of the present invention; [Diagram 2] FIG. 2 is a side view of one preferred and non-limiting embodiment or example of a non-suspended bulk acoustic resonator in accordance with the principles of the present invention; [Diagram 3] FIG. 2 is a side view of one preferred and non-limiting embodiment or example of a non-suspended bulk acoustic resonator in accordance with the principles of the present invention; [Figure 4A]FIG. 1 is an isolated plan view of one preferred and non-limiting embodiment or example of an interdigitated electrode shape that can be used as a top conductive layer, an optional bottom conductive layer, or both, of a non-suspended bulk acoustic resonator in accordance with the principles of the present invention. [Figure 4B] FIG. 1 is an isolated plan view of one preferred and non-limiting embodiment or example of a comb electrode shape that can be used as a top conductive layer, an optional bottom conductive layer, or both, of a non-suspended bulk acoustic resonator in accordance with the principles of the present invention. [Figure 4C] FIG. 1 is an isolated plan view of one preferred and non-limiting embodiment or example of a thin plate electrode shape that can be used as a top conductive layer, an optional bottom conductive layer, or both, of a non-suspended bulk acoustic resonator in accordance with the principles of the present invention. [Figure 5A] 4 is a cross-sectional view of a preferred and non-limiting embodiment or example taken along line AA in each of FIGS. 1-3. FIG. [Figure 5B] 4 is a cross-sectional view of a preferred and non-limiting embodiment or example taken along line BB in each of FIGS. 1-3. FIG. [Figure 6A] 4 is a cross-sectional view of a preferred and non-limiting embodiment or example taken along line AA in each of FIGS. 1-3. FIG. [Figure 6B] 4 is a cross-sectional view of a preferred and non-limiting embodiment or example taken along line BB in each of FIGS. 1-3. FIG. [Figure 7A] 4 is a cross-sectional view of a preferred and non-limiting embodiment or example taken along line AA in each of FIGS. 1-3. FIG. [Figure 7B] 4 is a cross-sectional view of a preferred and non-limiting embodiment or example taken along line BB in each of FIGS. 1-3. FIG. [Figure 7C] 7A-7B are side views of one preferred and non-limiting embodiment or example of a non-suspended bulk acoustic resonator according to the principles of the present invention with material removed on either side of the first and second connection structures and of the tether conductors as shown in FIG. [Figure 8A]4 is a cross-sectional view of a preferred and non-limiting embodiment or example taken along line AA in each of FIGS. 1-3. FIG. [Figure 8B] 4 is a cross-sectional view of a preferred and non-limiting embodiment or example taken along line BB in each of FIGS. 1-3. FIG. [Figure 8C] 8A-8B are side views of one preferred and non-limiting embodiment or example of a non-suspended bulk acoustic resonator according to the principles of the present invention with material removed on either side of the first and second connection structures and of the tether conductors as shown. [Figure 8D] 8A-8B are side views of one preferred and non-limiting embodiment or example of a non-suspended bulk acoustic resonator according to the principles of the present invention with material removed on either side of the first and second connection structures and of the tether conductors as shown. [Figure 9A] 4 is a cross-sectional view of a preferred and non-limiting embodiment or example taken along line AA in each of FIGS. 1-3. FIG. [Figure 9B] 4 is a cross-sectional view of a preferred and non-limiting embodiment or example taken along line BB in each of FIGS. 1-3. FIG. [Figure 9C] 9A-9B are side views of one preferred and non-limiting embodiment or example of a non-suspended bulk acoustic resonator according to the principles of the present invention with material removed on either side of the first and second connection structures and of the tether conductors as shown in FIG. [Figure 9D] 9A-9B are side views of one preferred and non-limiting embodiment or example of a non-suspended bulk acoustic resonator according to the principles of the present invention with material removed on either side of the first and second connection structures and of the tether conductors as shown in FIG. [Figure 10] Graph of frequency vs. dB for a resonator body with a bottom conductive layer in the form of a thin plate electrode and a top conductive layer in the form of a comb electrode with a finger pitch of 1.8 μm. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] For the purposes of the following detailed description, it should be understood that the present invention can take various alternative variations and sequence of steps, unless expressly stated to the contrary. It should also be understood that the specific elements and methods described in the following patent specification are merely exemplary embodiments, examples, or aspects of the present invention. Furthermore, in the preferred and non-limiting embodiments, examples, or aspects, other than in any working example, or unless otherwise specifically indicated, all numbers expressing the quantities of elements used in the patent specification and claims are to be understood in all instances as being modified by the term "about". Thus, unless specifically indicated to the contrary, the numerical parameters set forth in the following patent specification and the appended claims are approximations that may vary depending on the desired properties obtained by the present invention. Thus, each numerical parameter should be construed at least in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0013] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible, however, any numerical values ​​inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0014] It is also to be understood that any numerical range recited herein is intended to include all subranges subsumed therein. For example, a range of "1 to 10" is intended to include all subranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, i.e., having a minimum value of 1 or more and a maximum value of 10 or less.

[0015] It should also be understood that the specific elements and steps illustrated in the attached drawings and described in the following patent specification are merely exemplary embodiments, examples, or aspects of the invention. Thus, specific dimensions and other physical characteristics associated with the embodiments, examples, or aspects disclosed herein are not to be considered limiting. Certain preferred and non-limiting embodiments, examples, or aspects of the invention are described with reference to the attached figures, in which like reference numbers correspond to the same or functionally equivalent elements.

[0016] In this application, unless specifically stated otherwise, the use of the singular can include the plural and the plural encompasses the singular. Further, in this application, unless specifically stated otherwise, the use of "or" means "and / or," even if "and / or" may clearly be used in some instances. Further, in this application, unless specifically stated otherwise, the use of "a" or "an" means "at least one."

[0017] For purposes of the following description, the terms "end", "upper", "lower", "right", "left", "vertical", "horizontal", "top", "bottom", "lateral", "longitudinal" and derivatives thereof refer to the examples as oriented in the drawing figures. However, it should be understood that the examples may take various alternative variations and step sequences unless expressly stated to the contrary. It should also be understood that the specific examples shown in the accompanying drawings and described in the following patent specification are merely illustrative examples or aspects of the invention. Thus, the specific examples or aspects disclosed herein should not be construed as limiting.

[0018] 1, in one preferred and non-limiting embodiment or example, an unsuspended bulk acoustic resonator (UBAR) 2 in accordance with the principles of the present invention, which may be operable in a bulk acoustic mode, may include a resonator body 4 that may include a stack of layers comprising, from top to bottom, a top conductive layer 6, a piezoelectric layer 8, an optional bottom conductive layer 10, and an element layer 12. In the example shown in FIG. 1, UBAR 2, the bottom surface of element layer 12 may be mounted, for example, directly to a mounting substrate or carrier 14.

[0019] With reference to Figure 2 and continuing reference to Figure 1, in one preferred and non-limiting embodiment or example, another example of a UBAR 2 according to the principles of the present invention can be similar to the UBAR 2 shown in Figure 1, except that at least the resonator body 4 of Figure 2 can include an optional substrate 16 between the device layer 12 and the carrier 14. In an example, the bottom surface of the device layer 12 can be mounted, e.g., directly mounted to a top surface of the substrate 16, and the bottom surface of the substrate 16 can be mounted, e.g., directly mounted to the carrier 14.

[0020] 3 and continuing reference to FIGS. 1 and 2, another example of a UBAR 2 according to the principles of the present invention can be similar to the UBAR 2 shown in FIG. 2, except that in one preferred and non-limiting embodiment or example, at least the resonator body 4 of FIG. 3 can include an optional second substrate 16-1 between the element layer 12 and the piezoelectric layer 8 or optional bottom conductive layer 10, if provided, and / or an optional second element layer 12-1 between the second substrate 16-1 and the piezoelectric layer 8 or optional bottom conductive layer 10, if provided. In one preferred and non-limiting embodiment or example, it is contemplated that the resonator body 4 of FIG. 3 can further include one or more additional element layers 12 (not specifically shown) and / or one or more additional substrates 16 (not specifically shown), as deemed appropriate and / or desirable. An example of a resonator body 4 having several element layers 12 and substrates 16 can include, in an exemplary order from a piezoelectric layer 8 or an optional bottom conductive layer 10 to a carrier 14, a first element layer, a first substrate, a second element layer, a second substrate, a third element layer, a third substrate, ... and so on. In one preferred and non-limiting embodiment or example where the resonator body 4 can include multiple element layers 12 and / or multiple substrates 16, each element layer 12 can be made of the same or different materials, and each substrate 16 can be made of the same or different materials. In one preferred and non-limiting embodiment or example, the number of element layers 12 and the number of substrates 16 can be different. In an example, in an exemplary order from a piezoelectric layer 8 or an optional bottom conductive layer 10 to a carrier 14, the resonator body 4 can include an element layer 12-1, a substrate 16-1, and an element layer 12 as the bottommost layer of the resonator body 4. Examples of materials that can be used to form each device layer 12 and each substrate 16 are described below.

[0021] In one preferred and non-limiting embodiment or example, as shown in Figures 1-3, one or more optional temperature compensating layers 90, 92, and 94 may be provided on the top surface of the top conductive layer 6, between the piezoelectric layer 8 or optional bottom conductive layer 10, if provided, and the element layer 12, and / or between the element layer 12 (or 12-1) and the substrate 16 (or 16-1), if provided. Each temperature compensating layer may include at least one of silicon and oxygen. In an example, each temperature compensating layer may include silicon dioxide or elemental silicon and / or elemental oxygen. When provided, the one or more optional temperature compensating layers 90, 92, and 94 may help to avoid changes in the resonant frequency of each example resonator body 4 shown in Figures 1-3 due to heat generated during use.

[0022] In plan view, each resonator body 4 and / or UBAR 2 described herein can have a square or rectangular shape, however, resonator bodies 4 and / or UBAR 2 having other shapes are envisioned.

[0023] 4A-4C, and continuing with reference to all previous figures, in one preferred and non-limiting embodiment or example, one or both of the conductive layer 6 and the optional conductive layer 10 can be in the form of an interdigitated electrode 18 (FIG. 4A) that can include conductive lines or fingers 20 supported by the rear surface 22 and interdigitated with conductive lines or fingers 24 and supported by the rear surface 26. In one preferred and non-limiting embodiment or example, one or both of the conductive layer 6 and the optional conductive layer 10 can be in the form of a comb electrode 27 (FIG. 4B) that can include conductive lines or fingers 28 extending from a first rear surface 30. The ends of the conductive lines or fingers 28 opposite the first rear surface 30 can be connected to an optional second rear surface 32 (shown in phantom in FIG. 4B). In one preferred and non-limiting embodiment or example, one or both of the conductive layer 6 and the optional conductive layer 10 can be in the form of a conductive sheet electrode 33 (FIG. 4C). Each line or finger 20, 24, and 28 is shown as a straight line. In examples, each line or finger 20, 24, and 28 may be a curved line or finger, a spiral line or finger, or any other suitable and / or desirable shape.

[0024] In one preferred and non-limiting embodiment or example, the top conductive layer 6 can be in the form of an interdigitated electrode 18, or a comb electrode 27, or a thin plate electrode 33. Independent of the form of the top conductive layer 6, the optional bottom conductive layer 10, if provided, can be in the form of an interdigitated electrode 18, or a comb electrode 27, or a thin plate electrode 33. Hereinafter, and for purposes of illustration only, in one preferred and non-limiting embodiment or example, the top conductive layer 6 is described as being in the form of a comb electrode 27 including a first rear surface 30 and an optional second rear surface 32, and the optional bottom conductive layer 10 is described as being in the form of a thin plate electrode 33. However, this should not be construed in a limiting sense, as the use of any one of the interdigitated electrodes 18, or comb electrodes 27, or thin plate electrodes 33 for the top conductive layer 6 in combination with any one of the interdigitated electrodes 18, or comb electrodes 27, or thin plate electrodes 33 for the optional bottom conductive layer 10 is envisioned.

[0025] In one preferred and non-limiting embodiment or example, the resonant frequency of each resonator body 4 instance having at least a top conductive layer 6 in the form of an interdigitated electrode 18 or comb electrode 27, regardless of its form, when the optional bottom conductive layer 10 is provided, can be adjusted or selected in a manner known in the art by appropriate selection of finger pitch 38 (see, e.g., FIGS. 4A-4B), where finger pitch 38=finger width+finger gap (between adjacent fingers). In examples where it is desired that each resonator body 4 instance resonates primarily in the transverse mode versus the thickness mode, but not all, the resonant frequency of the resonator body 4 can be increased by decreasing finger pitch 38. In examples where it is desired that each resonator body 4 instance resonates primarily in the thickness mode versus the transverse mode, but not all, the resonant frequency of the resonator body 4 can be decreased by increasing finger pitch 38.

[0026] In one preferred and non-limiting embodiment or example, each resonator body 4 example can resonate in a thickness mode, a transverse mode, or a composite or resultant mode that is a combination of thickness and transverse modes. In a thickness mode resonance, the acoustic wave resonates in the direction of the thickness of the piezoelectric layer 8, and the resonant frequency is based on the thickness of the piezoelectric layer 8 and the thickness of the top conductive layer 6 and the optional bottom conductive layer 10, if provided. The combination of the piezoelectric layer 8, the optional bottom conductive layer 10, if provided, and the top conductive layer 6 can be referred to as a piezoelectric stack. The acoustic velocity that determines the resonant frequency of each resonator body 4 example described herein is the resultant acoustic velocity of the piezoelectric stack. In the example, the resonant frequency f is determined by the resultant acoustic velocity V a This can be calculated by dividing by twice the thickness τ of the piezoelectric stack.

[0027] In transverse mode resonance, acoustic waves resonate in the transverse direction (x or y direction) of the piezoelectric layer 8, and the resonant frequency is determined by the resultant acoustic velocity V of the piezoelectric stack. a by twice the finger pitch, i.e., f=V a / 2(finger pitch). The finger pitch is large with a pitch size δ L From small pitch size δ S When the frequency is reduced to 100Hz, the frequency increase rate, PFI Calculated In the example, can be calculated by the following formula:

number

[0028] The composite mode resonance may include a thickness mode resonance portion and a transverse mode resonance portion. The transverse mode resonance portion L in the composite mode resonance is caused by the finger pitch 38 being increased by a large pitch size δ LFrom small pitch size δ S The actual or measured rate of frequency increase PFI Measured Calculated frequency increase rate PFI Calculated The value of the transverse mode resonance L may be greater than 100% if there is one or more uncontrolled or unpredictable variations. In an example, the resonator body 4 may resonate in a thickness mode, a transverse mode, or a composite mode. In an example of a composite mode resonance, the portion of the transverse mode resonance L may be 20% or more. In another example of a composite mode resonance, the portion of the transverse mode resonance L may be 30% or more. In another example of a composite mode resonance, the portion of the transverse mode resonance L may be 40% or more.

[0029] In one preferred and non-limiting embodiment or example, a resonator body 4 having an optional bottom conductive layer 10 in the form of a thin plate electrode 33 and a top conductive layer 6 in the form of a comb electrode 27 with a finger pitch 38 of 2.2 μm can resonate in a composite mode with modal resonant frequencies of Mode 1 resonant frequency=1.34 GHz, Mode 2 resonant frequency=2.03 GHz, and Mode 3 resonant frequency=2.82 GHz.

[0030] In an example, for a resonator body 4 having an optional bottom conductive layer 10 in the form of a thin plate electrode 33 and a top conductive layer 6 in the form of a comb electrode 27 with a finger pitch 38 of 1.8 μm, the resonator body 4 can resonate in a composite mode with mode resonance frequencies of Mode 1=1.49 GHz, Mode 2=2.38 GHz, and Mode 3=3.05 GHz. In this example, the percentage of transverse mode resonances L among the composite mode resonances can be Lmode1=53%, Lmode2=78%, and Lmode3=27%, respectively. See also FIG. 10, which is a frequency vs. dB graph for the resonator body 4 of this example. In FIG. 10, each peak 82, 84, and 86 represents the response of the resonator body 4 at Mode 1=1.49 GHz, Mode 2=2.38 GHz, and Mode 3=3.05 GHz, respectively.

[0031] In an example, for a resonator body 4 having an optional bottom conductive layer 10 in the form of a thin plate electrode 33 and a top conductive layer 6 in the form of a comb electrode 27 with a finger pitch 38 of 1.4 μm, the resonator body 4 may have modal resonance frequencies of Mode 1=1.79 GHz, Mode 2=2.88 GHz, and Mode 3=3.36 GHz. In this example resonator body 4, the proportions of transverse mode resonances L among the combined mode resonances may be Lmode1=70%, Lmode2=74%, and Lmode3=35%.

[0032] The above description of the resonator body 4 resonating in a thickness mode, a transverse mode, or a composite mode in the examples may also be applicable to each of the UBAR2 examples shown in FIGS. 1-3 , which may include a resonator body 4 in combination with one or more connecting structures 34 and 36, which are described in more detail below.

[0033] Continuing with reference to Figures 1-3, in one preferred and non-limiting embodiment or example, the bottom-most layer of each resonator body 4 shown in Figures 1-3 can be mounted directly to the carrier 14 utilizing any suitable and / or desired mounting technique, e.g., eutectic mounting, bonding, etc. As used herein, "mounted directly," "mounting ... directly," and similar phrases shall be understood as the bottom-most layer of each resonator body 4 shown in Figures 1-3 being positioned proximate to the carrier 14 and coupled to the carrier 14 in any suitable and / or desired manner, e.g., mounting, attachment, etc., in examples, by any suitable and / or desired means, e.g., eutectic bonding, conductive bonding, non-conductive bonding, etc. In one preferred and non-limiting embodiment or example, the carrier 14 can be a surface of a package, e.g., a conventional integrated circuit (IC) package. After the bottom layer of the resonator body 4 is mounted on the surface of the package, the resonator body 4 and, more generally, the UBAR 2 can be sealed in the package in a manner known in the art to protect the resonator body 4 and, more generally, the UBAR 2 against external environmental conditions. In an example, the use of a package such as, for example, a conventional ceramic IC package commercially available from NTK Ceramic Co., Ltd. of Japan for mounting the UBAR is envisaged. However, this should not be construed in a limiting sense, as it is envisaged that the resonator body 4 and / or the UBAR 2 can be mounted in any suitable and / or desirable package now known or later developed.

[0034] In another example, the carrier 14 can be a surface of a substrate, such as, for example, a sheet of ceramic, a sheet of conventional printed circuit board material, etc. The description of example substrates herein on which the bottom layer of each of the resonator bodies 4 and / or UBAR2 shown in Figures 1-3 can be mounted is for illustrative purposes only and should not be construed in a limiting sense. Rather, the carrier 14 can be made of any suitable and / or desirable material that is compatible with the material forming the bottom layer of each of the resonator bodies 4 and / or UBAR2 shown in Figures 1-3 and that allows for the use of the resonator bodies 4 and / or UBAR2 in a manner known in the art. The carrier 14 can have any shape deemed suitable and / or desirable by one of ordinary skill in the art. Thus, any description of a mounting substrate or carrier 14 herein should not be construed in a limiting sense.

[0035] Continuing with reference to FIGS. 1-3, in one preferred and non-limiting embodiment or example, each UBAR 2 may include one or more optional connection structures 34 and / or 36 that facilitate application of an electrical signal to the top conductive layer 6 and optional bottom conductive layer 10 of the resonator body 4, if provided. However, in one preferred and non-limiting embodiment or example, one or more optional connection structures 34 and / or 36 that may directly apply an electrical signal to the top conductive layer 6 and optional bottom conductive layer 10 of the resonator body 4, if provided, may be omitted (i.e., not provided). Thus, in an example, the UBAR 2 may comprise a resonator body 4 without the connection structures 34 and 36. In another example, the UBAR 2 may comprise a resonator body 4 and a single connection structure 34 or 36. For illustrative purposes only, in one preferred and non-limiting embodiment or example, a UBAR 2 is described that comprises a resonator body 4 and connection structures 34 and 36.

[0036] Each connection structure 34 and 36 may have any suitable and / or desirable shape, may be formed in any suitable and / or desirable manner, and may be fabricated from any suitable and / or desirable material that can facilitate providing separate electrical signals to the top conductive layer 6 and optional bottom conductive layer 10, if provided. In an example, where the top conductive layer 6 is in the form of a comb electrode 27 having only one rear surface 30 or 32, and the optional bottom conductive layer 10 is in the form of a comb electrode 27 having only one rear surface 30 or 32, or in the form of a thin plate electrode 33, electrical signals may be provided to each of the top conductive layer 6 and optional bottom conductive layer 10 via a single connection structure 34 or 36, which may be configured to provide separate electrical signals to the top conductive layer 6 and optional bottom conductive layer 10.

[0037] In another example, where at least one of the top conductive layer 6 or optional bottom conductive layer 10 has the form of an interdigitated electrode 18 or comb electrode 27 having two rear surfaces 30 and 32, separate connection structures 34 and 36 can be provided to separately provide one or more electrical signals to the rear surfaces 24 and 26 of the interdigitated electrode 18 and / or to the rear surfaces 30 and 32 of the comb electrode 27. The form of the top conductive layer 6 and optional bottom conductive layer 10, and the manner in which electrical signals are provided to the top conductive layer 6 and optional bottom conductive layer 10, if provided, are not intended to be construed in a limiting sense.

[0038] In one preferred and non-limiting embodiment or example, without wishing to be bound by any particular explanation, example, or theory, an example of first and second connection structures 34 and 36 that can be used in the example UBAR2 shown in Figures 1-3 is now described.

[0039] In one preferred and non-limiting embodiment or example, for purposes of illustration only, each connection structure 34 and 36 is described as having an extension of the various layers and / or substrates that form the various examples of resonator body 4 shown in Figures 1-3. However, this is not to be construed in a limiting sense as it is envisioned that each connection structure 34 and 36 can have any suitable and / or desired shape and / or structure that allows for the provision of one or more separate electrical signals to the top conductive layer 6 and optional bottom conductive layer 10, if provided.

[0040] In one preferred and non-limiting embodiment or example, referring to Figures 5A-5B, which may represent views along lines AA and BB in any one or all of Figures 1-3, Figure 5A shows a top conductive layer 6 in the form of a comb electrode 27, including a back surface 30 and an optional back surface 32, on the top surface of the piezoelectric layer 8. In an example, the top conductive layer 6 can alternatively be in the form of an interdigitated electrode 18. In one preferred and non-limiting embodiment or example, Figure 5B shows an optional bottom conductive layer 10 in the form of a thin plate electrode 33 below the piezoelectric layer 8 (shown in phantom in Figure 5B). In an example, the optional bottom conductive layer 10 can alternatively be in the form of an interdigitated electrode 18 or a comb electrode 27. For the purposes of the following example only, the top conductive layer 6 and the optional bottom conductive layer 10 are described as being in the form of a comb electrode 18, including a back surface 30 and an optional back surface 32, and in the form of a thin plate electrode 33, respectively. However, this should not be construed in a limiting sense.

[0041] In one preferred and non-limiting embodiment or example, the connection structures 34 and 36 can include bottom metal layers 40 and 44 (FIG. 5B) in contact with the thin plate electrode 33 forming the optional bottom conductive layer 10 of the resonator body 4. Each bottom layer 40 and 44 can be in the form of a thin plate covered by the piezoelectric layer 8. In an example, each bottom layer 40 and 44 can be an extension of the thin plate electrode 33 and can be formed simultaneously with the thin plate electrode 33. In another example, each bottom layer 40 and 44 can be formed separately from the thin plate electrode 33 and can be made from the same or different material as the thin plate electrode 33. In an example, the connection structures 34 and 36 can also include top metal layers 42 and 46 on the top surface of the piezoelectric layer 8 and in contact with the rear surface 30 and rear surface 32, respectively, of the comb electrode 27 forming the top conductive layer 6 of the resonator body 4.

[0042] In an example, the bottom metal layers 40 and 44 can be connected to the contact pads 48 on the top surfaces of the first and second connection structures 34 and 36 through conductive vias 50 formed in the piezoelectric layer 8 that extend between the contact pads 48 and the bottom metal layers 40 and 44. In an example, each top metal layer 42 and 46 can have the shape of a thin plate spaced from the corresponding contact pad 48 by a gap (not numbered). Each top metal layer 42 and 46 can also include a contact pad 58. Each contact pad 48 can be connected to a suitable signal source (not shown) that can be used to electrically drive / energize the optional bottom conductive layer 10 in any suitable and / or desirable manner, as needed. Similarly, each contact pad 58 can be connected to a suitable signal source (not shown) that can be used to drive / energize the top conductive layer 6 in any suitable and / or desirable manner, as needed.

[0043] As shown in Figures 5A-5B by reference numerals 18 and 27, the top conductive layer 6 can alternatively be in the form of interdigitated electrodes 18, and the optional bottom conductive layer 10 can alternatively be in the form of comb electrodes 27 or interdigitated electrodes 18.

[0044] 6A-6B, which may represent views along lines AA and BB in any one or all of FIGS. 1-3, in one preferred and non-limiting embodiment or example, the example shown in FIGS. 6A-6B is similar to the example shown in FIGS. 5A-5B, with at least the following exceptions: Bottom metal layers 40 and 44 may be in the form of a pair of spaced apart conductors 52 (as opposed to the conductive plate shown in FIGS. 5A-5B) connected to optional bottom conductive layer 10 in the form of plate electrode 33 by side conductors 54 and tether conductors 56, respectively. Top metal layers 42 and 46 may be in the form of conductors 60, respectively. Each conductor 60 may be connected to rear surface 30 or rear surface 32 of comb electrode 27 forming top conductive layer 6 by tether conductors 62. Tether conductors 62 may be vertically aligned with tether conductors 56 and spaced therefrom by piezoelectric layer 8. In an example, the width of tether conductor 62 can be less than the width of conductor 60, and the width of tether conductor 56 can be about the same as the width of tether conductor 62, as shown in FIGS. 6A-6B.

[0045] 7A-7B, which may represent views along lines AA and BB in any one or all of FIGS. 1-3, in one preferred and non-limiting embodiment or example, the example shown in FIGS. 7A-7B is similar to the example shown in FIGS. 6A-6B with at least the following exceptions: Some or all of the material of the connection structures 34 and 36 on either side of the tether conductor 62 and the tether conductor 56, if provided, of the connection structure may be removed, thereby forming a slot that may extend some or all of the distance from the top to the bottom of the UBAR 2 on either side of the tether conductor between the remaining portion of the connection structure and the resonator body 4. The removal of some or all of the material of the connection structures 34 and 36 on either side of the tether conductor of the connection structure may define a tether structure 76, which may include, in an example, the tether conductor 62, the tether conductor 56, if provided, and a portion of the piezoelectric layer 8 vertically aligned with the tether conductor 62.

[0046] 7C, and with continued reference to Figures 7A-7B, in one preferred and non-limiting embodiment or example, removal of some or all of the material forming each of the connection structures 34 and 36 on either side of tether conductor 62 and tether conductor 56, if provided, of said connection structures may be used in any of the examples of UBAR2 shown in Figures 1-3. For example, Figure 7C shows a side view of the example of UBAR2 shown in Figure 1 with the material of first and second connection structures 34 and 36 on either side of tether conductor 62 and tether conductor 56, if provided, of each of said connection structures removed as shown in Figures 7A-7B. As can be seen from Figures 7A-7C, the removed material of each connection structure on either side of tether conductor 62 and tether conductor 56, if provided, can include portions of top conductive layer 6, piezoelectric layer 8, optional bottom conductive layer 10, if provided, and element layer 12, so that in the views shown in Figures 7A-7B, no material is visible in the slots formed by the removal of these materials of each connection structure 34 and 36 on either side of tether conductor 62 and tether conductor 56, if provided, of said connection structure. In the example shown in Figures 7A-7C, each tether structure 76 can include, from top to bottom, tether conductor 62, a portion of piezoelectric layer 8 aligned perpendicular to tether conductor 62, optional tether conductor 56 (when bottom conductive layer 10 is present), and a portion of element layer 12 aligned perpendicular to tether conductor 62.

[0047] In another example, where UBAR2 includes substrate 16 (FIG. 2) shown in phantom in FIG. 7C and, optionally, one or more additional element layers 12-1 and / or substrates 16-1 (FIG. 3), the material forming substrate 16 and each additional element layer 12-1 and / or substrate 16-1, if provided, on either side of tether conductor 62 and tether conductor 56, if provided, of each connection structure 34 and 36 may also be removed, such that in the views shown in FIGS. 7A-7B, no material should be visible in the slots formed by the removal of these materials of each connection structure 34 and 36 on either side of tether conductor 62 and tether conductor 56, if provided, of said connection structures.

[0048] In an example, where the diagram shown in Figures 7A-7B is an example of the UBAR2 shown in Figure 2, each tether structure 76 can include, from top to bottom, tether conductors 62, a portion of piezoelectric layer 8 aligned vertically to tether conductors 62, optional tether conductors 56 (when optional bottom conductive layer 10 is present), a portion of element layer 12 aligned vertically to tether conductors 62, and a portion of substrate 16 aligned vertically to a portion of element layer 12. In another example, when the diagram shown in Figures 7A-7B is an example of UBAR2 shown in Figure 3, each tether structure 76 can include, from top to bottom, tether conductors 62, a portion of piezoelectric layer 8 aligned vertically to tether conductors 62, optional tether conductors 56 (when optional bottom conductive layer 10 is present), portions of element layers 12 and 12-1 aligned vertically to tether conductors 62, and portions of substrates 16 and 16-1 aligned vertically to tether conductors 62.

[0049] 8A-8B, which may represent views along lines AA and BB in any one or all of Figures 1-3, in one preferred and non-limiting embodiment or example, the example shown in Figures 8A-8B is similar to the example shown in Figures 7A-7B with at least the following exception: material forming all or part of at least one element layer 12 or 12-1 of each connection structure 34 and 36 is retained on both sides of the connection structure of tether conductor 62 and tether conductor 56, if provided, such that the material of the at least one element layer 12 or 12-1 is visible in slots on both sides of the connection structure of tether conductor 62 and tether conductor 56, if provided. In an example, where the diagrams shown in Figures 8A-8C are of the UBAR 2 shown in Figure 1, each tether structure 76 can include, from top to bottom, tether conductors 62, a portion of piezoelectric layer 8 aligned perpendicularly to tether conductors 62, and optional tether conductors 56 (when optional bottom conductive layer 10 is present). In this example, element layer 12 would be retained and visible in the slots shown in Figures 8A-8B.

[0050] 8A-8B is an example of UBAR2 shown in FIG. 2, each tether structure 76 may include, from top to bottom, tether conductors 62, a portion of piezoelectric layer 8 aligned perpendicular to tether conductors 62, optional tether conductors 56 (when optional bottom conductive layer 10 is present), and a portion of element layer 12 aligned perpendicular to tether conductors 62. In this example, element layer 12 would be retained and visible in the slots shown in FIG. 8A-8B, and substrate 16 (shown in phantom in FIG. 8C) below element layer 12 would also be retained but would not be visible in the slots shown in FIG. 8A-8B.

[0051] 8A-8B is the example of UBAR2 shown in FIG. 3, each tether structure 76 can include, from top to bottom, tether conductors 62, a portion of piezoelectric layer 8 aligned vertically to tether conductors 62, optional tether conductors 56 (when optional bottom conductive layer 10 is present), and a portion of element layer 12 aligned vertically to tether conductors 62. In an example, if element layer 12 is held and visible in the slots shown in FIGS. 8A-8B, substrate 16 below element layer 12 would also be held but not visible in the slots shown in FIGS. 8A-8B, and each tether structure 76 would still include a portion of element layer 12-1 and a portion of substrate 16-1 aligned vertically to tether conductors 62. In another example, if element layer 12-1 is retained and visible within the slots shown in Figures 8A-8B, substrates 16 and 16-1 and element layer 12 would also be retained but would not be visible within the slots shown in Figures 8A-8B.

[0052] In another example shown in Figure 8D, in the example of UBAR2 shown in Figure 1 or 2, each tether structure 76 can include, from top to bottom, tether conductor 62, a portion of piezoelectric layer 8 aligned perpendicularly to tether conductor 62, optional tether conductor 56 (when optional bottom conductive layer 10 is present), and, of each connection structure 34 and 36, tether conductor 62 and a portion of the body of element layer 12 aligned perpendicularly to tether conductor 62 exposed by partial removal of element layer 12 on either side of tether conductor 56, if provided. If the example shown in Figure 8D were the UBAR2 shown in Figure 2, substrate 16 (shown in phantom in Figure 8D) would be held below element layer 12 and would not be visible in the views shown in Figures 8A-8B.

[0053] In another example, in the example of UBAR2 shown in FIG. 3, each tether structure 76 can include, from top to bottom, tether conductor 62, a portion of piezoelectric layer 8 vertically aligned with tether conductor 62, optional tether conductor 56 (when optional bottom conductive layer 10 is present), and, of each connection structure 34 and 36, tether conductor 62 and a portion of the body of element layer 12 or element layer 12-1 vertically aligned with tether conductor 62 on either side of tether conductor 56, if provided, exposed by partial removal of said element layer 12 or 12-1 (similar to the partial removal of element layer 12 shown in FIG. 8D). In an example, a portion of the body of element layer 12 of UBAR2 shown in Figure 3 has been removed (similar to the partial removal of element layer 12 shown in Figure 8D), such that an internal portion of the material forming element layer 12 of UBAR2 shown in Figure 3 is visible in the slots shown in Figures 8A-8B, and each tether structure 76 can still include a portion of element layer 12-1 and substrate 16-1 aligned perpendicularly to tether conductors 62. In this example, substrate 16 is retained, i.e., no portion of substrate 16 is removed and would not be visible in the views shown in Figures 8A-8B.

[0054] 3 is removed (similar to the partial removal of element layer 12 shown in FIG. 8D), such that an internal portion of the material forming element layer 12-1 is visible in the slots shown in FIGS. 8A-8B, and each tether structure 76 may also include a portion of the body of element layer 12-1 perpendicularly aligned with tether conductors 62. In this example, substrates 16 and 16-1 and element layer 12 are retained, i.e., no portions of substrates 16 and 16-1 and element layer 12 are removed and would not be visible in the views shown in FIGS. 8A-8B.

[0055] 9A-9B, which may represent views along lines AA and BB in any one or all of FIGS. 1-3, for the UBAR2 shown in FIG. 2, in one preferred and non-limiting embodiment or example, the example shown in FIGS. 9A-9B is similar to the example shown in FIGS. 8A-8B, with at least the following exceptions: Each tether structure 76 may include a portion of the material forming the element layer 12, such that in the views shown in FIGS. 9A-9C, a portion of the substrate 16 may be visible in slots formed on either side of the tether conductors 62 and 56, if provided, of each connection structure 34 and 36. In this example, the substrate 16 is retained, and each tether structure 76 may include, from top to bottom, the tether conductors 62, a portion of the piezoelectric layer 8 aligned vertically to the tether conductors 62, the optional tether conductors 56 (when the optional bottom conductive layer 10 is present), and a portion of the element layer 12 aligned vertically to the tether conductors 62.

[0056] 3, in one preferred and non-limiting embodiment or example, when element layer 12 and substrates 16 and 16-1 are retained, in the view shown in FIG. 9A-9B, substrate 16-1 can be seen in slots formed on either side of tether conductors 62 and 56, if provided, of each connection structure 34 and 36. In this example, each tether structure 76 can include, from top to bottom, tether conductors 62, a portion of piezoelectric layer 8 vertically aligned with tether conductors 62, optional tether conductors 56 (when optional bottom conductive layer 10 is present), and a portion of element layer 12-1 vertically aligned with tether conductors 62.

[0057] In another example, in the UBAR2 shown in FIG. 3, when the substrate 16 is retained so that in the views shown in FIGS. 9A-9B the substrate 16 can be seen in slots formed on either side of the tether conductors 62 and tether conductors 56, if provided, of each connection structure 34 and 36, each tether structure 76 can include, from top to bottom, the tether conductors 62, a portion of the piezoelectric layer 8 aligned vertically to the tether conductors 62, the optional tether conductors 56 (when the optional bottom conductive layer 10 is present), a portion of the element layer 12-1 aligned vertically to the tether conductors 62, a portion of the substrate 16-1 aligned vertically to the tether conductors 62, and a portion of the element layer 12 aligned vertically to the tether conductors 62.

[0058] In another example shown in Figure 9D, in the example of UBAR2 shown in Figure 2, at the interface between substrate 16 and device layer 12, a portion of the material forming the body of substrate 16 can be removed laterally beneath resonator body 4 and connecting structures 34 and 36, resulting in exposed bottom portions 64 and 70 of connecting structures 34 and 36, exposed bottom portions 66 and 68 of resonator body 4, and exposed surfaces 72 and 74 of the body of substrate 16, as shown in Figure 9D. In this example, the removed portion of the material forming the body of substrate 16 can extend to a portion of the material of substrate 16 aligned perpendicularly to each tether structure 76 in the plane of Figure 9D. In this example, each tether structure 76 can include, from top to bottom, tether conductor 62, a portion of piezoelectric layer 8 aligned vertically to tether conductor 62, optional tether conductor 56 (when optional bottom conductive layer 10 is present), a portion of element layer 12 aligned vertically to tether conductor 62, and a portion of substrate 16 adjacent to a portion of element layer 12 and aligned vertically to tether conductor 62. In this example, surfaces 72 and 74 can be seen in the slots shown in Figures 9A-9B.

[0059] In another alternative, in the example of UBAR2 shown in FIG. 3, a portion of the material forming substrate 16-1 or 16 can be removed laterally beneath resonator body 4 and connecting structures 34 and 36, similar to the removal of material forming substrate 16 in FIG. 9D, such that a surface of the material forming substrate 16-1 or 16 (such as surfaces 72 and 74) is exposed and may be visible in the slots shown in FIGS. 9A-9B.

[0060] In an example, the surfaces (such as surfaces 72 and 74) of the material forming the substrate 16-1 of the UBAR2 example of FIG. 3 are exposed and can be seen within the slots shown in FIGS. 9A-9B. Each tether structure 76 can also include a portion of the element layer 12-1 aligned perpendicular to the tether conductor 62 and a portion of the material forming the substrate 16-1 aligned perpendicular to the tether conductor 62 and proximate to the element layer 12-1. In this example, only a portion of the body of the substrate 16-1 is removed to form each slot, and the element layer 12 and the substrate 16 are retained, that is, the element layer 12 and the substrate 16 have no portions removed and are not visible in the figures shown in FIGS. 9A-9B.

[0061] In another example, the surfaces (such as surfaces 72 and 74) of the material forming the substrate 16 of the UBAR2 example of FIG. 3 are exposed and can be seen within the slots shown in FIGS. 9A-9B. Each tether structure 76 can also include a portion of the element layer 12-1 aligned perpendicular to the tether conductor 62, a portion of the substrate 16-1 aligned perpendicular to the tether conductor 62, a portion of the element layer 12 aligned perpendicular to the tether conductor 62, and a portion of the material forming the substrate 16 aligned perpendicular to the tether conductor 62 and proximate to the element layer 12. In this example, only a portion of the body of the substrate 16 is removed to form each slot.

[0062] In one preferred and non-limiting embodiment or example, in any of the examples discussed above where the bottom conductive layer 10 is absent, the bottom metal layers 40 and 44 of the connection structures 34 and 36 may be absent.

[0063] In one preferred and non-limiting embodiment or example, each tether structure 76 described above can include at least tether conductors 62, optional tether conductors 56 (when optional bottom conductive layer 10 is present), and only a portion of piezoelectric layer 8 that is vertically aligned with tether conductors 62. In another preferred and non-limiting embodiment or example, each tether structure 76 can also include only a portion of one or more of element layer 12, substrate 16, element layer 16-1, and / or substrate 16-1 that is vertically aligned with tether conductors 62. However, this is not to be construed in a limiting sense.

[0064] 1-3, the widths of at least the top conductive layer 6, optional bottom conductive layer 10, if provided, and a portion of the piezoelectric layer 8 below the top conductive layer 6 can all be the same. Also, or alternatively, in the example, the widths and / or dimensions of the element layer 12, substrate 16, and element layer 12-1 and / or substrate 16-1, if provided, can all be the same as the widths and / or dimensions of the top conductive layer 6, optional bottom conductive layer 10, if provided, and piezoelectric layer 8.

[0065] In one preferred and non-limiting embodiment or example, any one or more of the surfaces of any of the example resonator bodies 4 shown in Figures 1-3 and / or any one or more of the connection structures 34 and / or 36, if provided, may be etched as deemed appropriate and / or desirable to optimize the quality factor and / or insertion loss of any of the example UBAR 2 shown in Figures 1-3. For example, the top and bottom surfaces of any of the example resonator bodies 4 shown in Figures 1-3 may be etched. Also, or alternatively, one or more side surfaces of any of the example resonator bodies 4 shown in Figures 1-3 may be etched, such that each of said side surfaces may be vertically planar.

[0066] In one preferred and non-limiting embodiment or example, when the top conductive layer 6, or the bottom conductive layer 10 if an optional bottom conductive layer 10 is provided, or both are in the form of an interdigitated electrode 18, the rear surface 22 or 26 of one of said interdigitated electrodes 18 can be connected to and driven by a suitable signal source, while the other rear surface 22 or 26 can be not connected to a signal source. In another preferred and non-limiting embodiment or example, when the top conductive layer 6, or the bottom conductive layer 10 if an optional bottom conductive layer 10 is provided, or both are in the form of an interdigitated electrode 18, the rear surface 22 of said interdigitated electrode 18 can be connected to and driven by one signal source, and the rear surface 26 of said interdigitated electrode 18 can be connected to and driven by a second signal source. In an example, the second signal source can be the same as or different from the first signal source.

[0067] In one preferred and non-limiting embodiment or example, each instance of device layer 12 (or 12-1) is 60×10 6 Pa·s / m 3 In another example, each embodiment of element layer 12 (or 12-1) can have an acoustic impedance of 90×10 6 Pa·s / m 3 In another example, each embodiment of element layer 12 (or 12-1) can have an acoustic impedance of 500×10 6 Pa·s / m 3 In one preferred and non-limiting embodiment or example, each substrate layer 16 can have an acoustic impedance of 100×10 6 Pa·s / m 3 In another example, each substrate layer 16 can have an acoustic impedance of 60×10 6 Pa·s / m 3 It may have the following acoustic impedance:

[0068] In one preferred and non-limiting embodiment or example, the reflectivity (R) of acoustic waves at the interface between the element layer 12 and the piezoelectric layer 8 or the optional bottom conductive layer 10, if provided, can be greater than 50%. In another example, the reflectivity (R) of acoustic waves at the interface between the element layer 12 and the piezoelectric layer 8 or the optional bottom conductive layer 10, if provided, can be greater than 70%. In another example, the reflectivity (R) of acoustic waves at the interface between the element layer 12 and the piezoelectric layer 8 or the optional bottom conductive layer 10, if provided, can be greater than 90%.

[0069] In one preferred and non-limiting embodiment or example, the reflectivity (R) of acoustic waves at the interface between element layer 12 or 12-1 and piezoelectric layer 8 or optional bottom conductive layer 10, if provided, can be greater than 70%. In an example, the reflectivity R at the interface of any two layers 6 and 8, 8 and 10, 8 or 10 and 12 or 12-1, or 12 or 12-1 and 16 or 16-1, or at the interface between element layer 12 or 12-1 and substrate 16 or 16-1, can be determined by the following formula:

[0070] R = |(Zb-Za) / (Za+Zb)|

[0071] where Z a =acoustic impedance of a first layer, e.g., piezoelectric layer 8, or an optional bottom conductive layer 10, if provided, located on a second layer;

[0072] Zb=acoustic impedance of the second layer, eg, element layer 12.

[0073] Other examples of the first and second layers may include embodiments of device layer 12 or 12-1 on substrate 16 or 16-1.

[0074] In one preferred and non-limiting embodiment or example, the total reflectance (R) of any of the example resonator bodies 4 shown in Figures 1-3 can be >90%.

[0075] In one preferred and non-limiting embodiment or example, device layer 12 can be a layer of diamond formed in a manner well known in the art. In an example, substrate 16 can be formed from silicon.

[0076] In one preferred and non-limiting embodiment or example, the device layer 12 formed of diamond can be grown by chemical vapor deposition (CVD) of diamond on the substrate 16 or 16-1 or a sacrificial substrate (not shown). In one preferred and non-limiting embodiment or example, the optional bottom conductive layer 10, piezoelectric layer 8, and top conductive layer 6 can be deposited on the device layer 12 and patterned as required (e.g., interdigitated electrodes 27 or interdigitated electrodes 18) using conventional semiconductor processing techniques not further described herein.

[0077] As used herein, each temperature compensating layer 90, 92, and 94 can include at least one of silicon and oxygen. For example, each temperature compensating layer can include silicon dioxide, or elemental silicon, and / or elemental oxygen.

[0078] In one preferred and non-limiting embodiment or example, each UBAR 2 shown in Figures 1-3 can have an unloaded quality factor of 100 or more. In another example, each UBAR 2 shown in Figures 1-3 can have an unloaded quality factor of 50 or more. In one preferred and non-limiting embodiment or example, the thickness of the piezoelectric layer 8, each element layer 12, and each substrate 16, if provided, of each example resonator body 4 shown in Figures 1-3 can be selected in any suitable and / or desirable manner to optimize the performance of the resonator body 4. Similarly, in an example, the dimensions of each example resonator body 4 shown in Figures 1-3 can be selected for target performance such as, without limitation, insertion loss, power handling capability, and heat dissipation. In one preferred and non-limiting embodiment or example, when diamond is used as the material of the element layer 12, the surface of said diamond layer at the interface with the bottom layer 12 can be optically finished and / or physically dense. In examples, the diamond material forming the device layer 12 can be undoped or doped, e.g., P-type or N-type. The diamond material can be polycrystalline, nanocrystalline, or ultrananocrystalline. In examples, when silicon is used as the material for each embodiment of the substrate 16, the silicon can be undoped or doped, e.g., P-type or N-type, and monocrystalline or polycrystalline. The diamond material forming the device layer can be 20 cm -1 The Raman half-width may be as follows:

[0079] In one preferred and non-limiting embodiment or example, the piezoelectric layer 8 can be formed of ZnO, AlN, InN, alkali or alkaline earth metal niobates, alkali or alkaline earth metal titanates, alkali or alkaline earth metal tantalites, GaN, AlGaN, lead zirconate titanate (PZT), polymers, or doped forms of any of the aforementioned materials.

[0080] In one preferred and non-limiting embodiment or example, the element layer 12 can be formed of any suitable and / or desirable high acoustic impedance material. 6 Pa·s / m 3 From 630×10 6 Pa·s / m 3 Materials with an acoustic impedance between or above this level can be considered high acoustic impedance materials. Examples of typical high acoustic impedance materials include diamond (approximately 630×10 6 Pa·s / m 3 ), W (approx. 99.7 x 10 6 Pa·s / m 3 ), Al, Pt, Pd, Mo, Cr, Ti, Ta, elements in Groups 3A or 4A of the Periodic Table, transition elements in Groups 1B, 2B, 3B, 4B, 5B, 6B, 7B, or 8B of the Periodic Table, ceramics, glasses, and polymers. This list of high acoustic impedance materials is not intended to be limiting.

[0081] In one preferred and non-limiting embodiment or example, the substrate 16 can be formed of any suitable and / or desirable low acoustic impedance material. 6 Pa·s / m 3 From 30×10 6 Pa·s / m 3 Materials with an acoustic impedance between 10 and 200 nm can be considered low acoustic impedance materials. Examples of typical low acoustic impedance materials include ceramics, 6 Pa·s / m 3 From 30×10 6 Pa·s / m 3 Glasses, crystals, and minerals, ivory (1.4 × 10 6 Pa·s / m 3 ), Alumina / Sapphire (25.5×10 6 Pa·s / m 3 ), alkali metal K (1.4×10 6 Pa·s / m 3 ), and silicon (19.7 × 10 6 Pa·s / m3 ). This list of low acoustic impedance materials is not to be construed in a limiting sense.

[0082] In one preferred and non-limiting embodiment or example, depending on the selection of materials forming each instance of the resonator body 4, one or more materials that are typically considered to be high acoustic impedance materials can function as low acoustic impedance materials for the resonator body 4. For example, if diamond is used as the material for the element layer 12, W can be used as the material for the substrate 16. Thus, by achieving the desired reflectivity R (discussed above) at the interface of the two layers or substrates of the resonator body 4, it can be determined which materials can be used as high acoustic impedance materials and which materials can be used as low acoustic impedance materials.

[0083] In one preferred and non-limiting embodiment or example, a bulk acoustic resonator according to the principles of the present invention may include a resonator body 4. The resonator body 4 may include a piezoelectric layer 8, an element layer 12, and a top conductive layer 6 on the piezoelectric layer 8 opposite the element layer 12. Substantially all of the surface of the element layer 12 opposite the piezoelectric layer is for mounting the resonator body 4 to a carrier 14 that is separated from the resonator body 4. In an example, it is desirable, but not essential, that all of the surface of the element layer opposite the piezoelectric layer may be for mounting the entire resonator body to the carrier. In an example, it is desirable, but not essential, that the bulk acoustic resonator may include a connection structure 34 or 36 for conducting a signal to the top conductive layer. In an example, the element layer may include diamond. In an example, the top conductive layer 6 may include a plurality of spaced apart conductive lines or fingers. In an example, the resonator body 4 may further include an optional bottom conductive layer 10 between the piezoelectric layer 8 and the element layer 12.

[0084] In one preferred and non-limiting embodiment or example, the resonator body 4 can further include a substrate 16 attached to the element layer 12 opposite the piezoelectric layer 8. In an example, a surface of the element layer 12 can be mounted in its entirety to the substrate 16. In an example, a surface of the substrate 16 facing the carrier 14 can be for mounting in its entirety directly to the carrier 14.

[0085] In one preferred and non-limiting embodiment or example, the surface of the device layer 12 that faces the carrier 14 is capable of being mounted in its entirety directly to the substrate 16. In the example, the surface of the device layer 12 that faces the carrier 14 is for mounting in its entirety directly to the carrier 14.

[0086] In one preferred and non-limiting embodiment or example, the resonator body 4 may further include a second element layer 12-1 between the substrate 16 and the piezoelectric layer 8, or a second substrate 16-1 between the substrate 16 and the piezoelectric layer 8, or both.

[0087] In one preferred and non-limiting embodiment or example, as used herein, "mounting in its entirety" can mean mounting one layer or substrate directly or indirectly to another layer or substrate. In an example, as used herein, "mounting in its entirety" can also or alternatively mean that there is no intentionally introduced space or gap between one layer or substrate and another layer or substrate. In another example, as used herein, "mounting in its entirety" can also or alternatively include a naturally occurring space that may be formed naturally (but unintentionally) between one layer or substrate and another layer or substrate.

[0088] While the present invention has been described in detail for purposes of illustration based on what are presently considered to be the most practical preferred and non-limiting embodiments, examples, or aspects, it should be understood that such details are for the purpose only, and that the present invention is not limited to the disclosed preferred and non-limiting embodiments, examples, or aspects, but rather is intended to encompass modifications and equivalent arrangements within the spirit and scope of the appended claims. For example, it should be understood that the present invention contemplates that, to the extent possible, one or more features of any preferred and non-limiting embodiment, example, aspect, or appended claim can be combined with one or more features of any other preferred and non-limiting embodiment, example, aspect, or appended claim.

Claims

1. 1. A bulk acoustic resonator comprising: a piezoelectric layer having a thickness; a first conductive layer disposed adjacent to the piezoelectric layer, the first conductive layer including a plurality of elongated interdigitated first conductive elements spaced apart from one another at a first pitch, each of the first conductive elements electrically connected to a first back section at a first end of the first conductive element and electrically connected to a second back section at a second end of the first conductive element opposite the first end; a second conductive layer disposed adjacent the piezoelectric layer on an opposite side of the piezoelectric layer from the first conductive layer; a resonator body including: the resonator body is configured to resonate in a composite acoustic resonance mode (C), the composite acoustic resonance mode (C) being a combination of (i) a thickness mode of the acoustic resonance defined by the thickness and (ii) a transverse mode of the acoustic resonance (L) defined by the first pitch; A bulk acoustic resonator in which the transverse mode (L) constitutes 20% or more of the intensity (dB) of the composite mode (C).

2. 10. The bulk acoustic resonator of claim 1, further comprising an element layer disposed adjacent to the piezoelectric layer, wherein a first surface of the element layer opposite the piezoelectric layer is configured to support the resonator body adjacent a carrier.

3. The bulk acoustic resonator of claim 2 , wherein the element layer is disposed on an opposite side of the piezoelectric layer from the first conductive layer.

4. 3. The bulk acoustic resonator of claim 2, comprising a connection structure disposed adjacent to the resonator body and formed from the piezoelectric layer, the element layer, and the first conductive layer of the resonator body, the connection structure being separated from the resonator body by a slot, the connection structure having a tether structure connected to the slot between the connection structure and the resonator body, the connection structure having a conductive via configured to conduct an electrical signal to the first conductive layer of the resonator body across the tether structure.

5. The bulk acoustic resonator of claim 2 wherein the element layer comprises diamond.

6. 10. The bulk acoustic resonator of claim 1, wherein the second conductive layer includes a plurality of second conductive elements spaced apart from one another at a second pitch.

7. The bulk acoustic resonator of claim 6 , wherein the first pitch is equal to the second pitch.

8. The bulk acoustic resonator of claim 4 , wherein the second conductive layer comprises a conductive thin plate.

9. 3. The bulk acoustic resonator of claim 2, wherein the resonator body further comprises at least one temperature compensating layer disposed on the first conductive layer opposite the piezoelectric layer or between the piezoelectric layer and the element layer.

10. The bulk acoustic resonator of claim 2 , wherein all of the first surfaces of the device layers facing the carrier are configured to be mounted directly to the carrier in their entirety.

11. the resonator body further comprises a substrate disposed adjacent the element layer on an opposite side from the piezoelectric layer; the first surface of the device layer is mounted to the substrate; The bulk acoustic resonator of claim 2 , wherein a second surface of the substrate facing the carrier is mounted to the carrier.

12. The bulk acoustic resonator of claim 11 , wherein the first surface of the device layer is mounted in its entirety directly to the substrate.

13. The bulk acoustic resonator of claim 11 , wherein the substrate comprises silicon.

14. 12. The bulk acoustic resonator of claim 11 , wherein the resonator body further comprises at least one temperature-compensating layer disposed on the first conductive layer opposite the piezoelectric layer, between the piezoelectric layer and the element layer, or between the element layer and the substrate.

15. The resonator body is another element layer disposed between the substrate and the piezoelectric layer; or The bulk acoustic resonator of claim 11 , further comprising: another substrate disposed between the substrate and the piezoelectric layer; or both.

16. The element layer is 60×10 ６ Pa·s / m ３ and the substrate has an acoustic impedance of 60×10 or more. ６ Pa·s / m ３ 12. The bulk acoustic resonator of claim 11, having an acoustic impedance of:

17. 3. The bulk acoustic resonator of claim 2, comprising a connection structure disposed adjacent to the resonator body and formed from the piezoelectric layer, the element layer, and the first conductive layer of the resonator body, the connection structure being separated from the resonator body by a slot, the connection structure having a tether structure connected to the slot between the connection structure and the resonator body, the connection structure having a conductive via configured to conduct an electrical signal to the first conductive layer of the resonator body across the tether structure.

18. 10. The bulk acoustic resonator of claim 1, wherein the second conductive layer comprises a plurality of interdigitated second conductive elements spaced apart from one another at a second pitch.

19. The bulk acoustic resonator of claim 1, wherein the composite mode (C) of the acoustic resonance has first, second and third mode resonant frequencies, the first mode resonant frequency exceeding 1.34 GHz, the second mode resonant frequency exceeding 2.03 GHz and the third mode resonant frequency exceeding 2.82 GHz.

20. The bulk acoustic resonator of claim 19, wherein the resonant frequency of the first mode is less than 1.79 GHz, the resonant frequency of the second mode is less than 2.88 GHz, and the resonant frequency of the third mode is less than 3.36 GHz.

21. The bulk acoustic resonator of claim 1, wherein the first pitch is between 1.4 μm and 2.2 μm.

22. The bulk acoustic resonator of claim 6, wherein each of the second conductive elements is electrically connected to a third rear portion at a first end of the second conductive element and electrically connected to a fourth rear portion at a second end of the second conductive element opposite the first end.

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