Acoustic resonators can be used to implement signal processing functions in various electronic applications. For example, some cellular phones and other communication devices use acoustic resonators to implement frequency filters for transmitted and/or received signals.
Several different types of acoustic resonators can be used according to different applications. For example, different applications may use bulk acoustic wave (BAW) resonators such as thin film bulk acoustic resonators (FBARs), coupled resonator filters (CRFs), double bulk acoustic resonators (DBARs), or solidly mounted resonators (SMRs).
As illustrated in
During typical operation, an electric field is applied between bottom and top electrodes 105 and 115. In response to this electrical field, the reciprocal or inverse piezoelectric effect causes acoustic resonator 100 to mechanically expand or contract depending on the polarization of the piezoelectric material, as indicated by an arrow in
The longitudinal acoustic wave, usually called a piston mode, is electrically excited by a vertical electric field between electrode plates and has a form of laterally uniform motion with the boundaries of motion determined by an overlap of top and bottom electrodes and the piezoelectric material. Lateral acoustic waves, usually called lateral modes, are excited at the edges of the piston mode motion and facilitate continuity of appropriate mechanical particle velocities and stresses between electrically excited and non-excited regions. In general, lateral modes are specific forms of motion supported by a mechanical stack and have both longitudinal and shear components. The lateral modes can either propagate freely (so called propagating modes) or exponentially decay (so called evanescent and complex modes) from the point of excitation. These modes can be excited both by a lateral structural discontinuity (for example, at an interface between regions of different thicknesses in a membrane, or at the edge of a top or bottom electrode) or by electric field discontinuity (for example, at an edge of a top electrode where the electric field is terminated abruptly). The lateral modes generally have a deleterious impact on FBAR functionality.
For longitudinal waves, where a thickness d of piezoelectric layer 110 and of the top and bottom electrodes equals an odd (1, 3, 5 . . . ) integer multiple of half the wavelength λ of the acoustic waves, resonance states and/or acoustic resonance vibrations will occur. Because each acoustic material has a different propagation velocity for the acoustic wave, the fundamental resonance frequency for any given polarization (for example, corresponding to horizontal shear HS, thickness shear TS and thickness extensional TE lowest and higher order modes) will then be inversely proportional to a weighted sum of all thicknesses of the resonator layers.
The piezoelectric properties and, therefore the resonance properties of an acoustic resonator depend on various factors, such as the piezoelectric material, the production method, the polarization impressed upon the piezoelectric material during manufacturing, and the size of the crystals, to name but a few.
An acoustic resonator can be employed in various types of electrical filters, such as radio frequency (RF) filters and microwave filters. In addition, acoustic resonators can be combined in various ways to produce a variety of filter configurations. The performance of an RF or microwave filter constructed with an acoustic resonator depends on the performance of the acoustic resonator, which can be expressed in terms of the resonator's parallel resistance Rp, series resistance Rs and its electromechanical coupling coefficient Kt2.
Referring to
An acoustic resonator can also be employed in an oscillator. Where an acoustic resonator is employed in an oscillator, the performance of the oscillator (e.g., phase noise) is affected by the Rp or Kt2 of the acoustic resonator. Moreover, as with filters, it is also desirable to provide an oscillator with an acoustic resonator having a higher Rp or Kt2 and lower Rs.
Unfortunately, many design choices that increase the Rp of an acoustic resonator tend to decrease the Kt2 of the acoustic resonator, and vice versa. In other words, there is generally a tradeoff between Rp and Kt2. Consequently, applications requiring high Rp may be required to sacrifice Kt2, and applications requiring a high Kt2 may be required to sacrifice Rp. In addition, because mechanisms determining Rp values in acoustic resonators involve scattering of multiple modes at various impedance mismatch interfaces, effectiveness of design choices to increase Rp, for example, depend on specific stack design, which is however determined by specific application of the resonator. Thus designs, frames for instance, aimed for increasing Rp may work for some acoustic stacks and may not work for the different acoustic stacks. What is needed, therefore, are acoustic resonator structures that can provide appropriate values of Rp and electromechanical coupling coefficient Kt2 according to the demands of different applications.
The illustrative embodiments are best understood from the following detailed description when read with the accompanying drawing figures. It is emphasized that the various features are not necessarily drawn to scale. In fact, the dimensions may be arbitrarily increased or decreased for clarity of discussion. Wherever applicable and practical, like reference numerals refer to like elements.
In the following detailed description, for purposes of explanation and not limitation, example embodiments disclosing specific details are set forth in order to provide a thorough understanding of the present teachings. However, it will be apparent to one having ordinary skill in the art having the benefit of the present disclosure that other embodiments according to the present teachings that depart from the specific details disclosed herein remain within the scope of the appended claims. Moreover, descriptions of well-known apparatuses and methods may be omitted so as to not obscure the description of the example embodiments. Such methods and apparatuses are clearly within the scope of the present teachings.
The terminology used herein is for purposes of describing particular embodiments only, and is not intended to be limiting. The defined terms are in addition to the technical, scientific, or ordinary meanings of the defined terms as commonly understood and accepted in the relevant context.
The terms ‘a’, ‘an’ and ‘the’ include both singular and plural referents, unless the context clearly dictates otherwise. Thus, for example, ‘a device’ includes one device and plural devices. The terms ‘substantial’ or ‘substantially’ mean to within acceptable limits or degree. The term ‘approximately’ means to within an acceptable limit or amount to one of ordinary skill in the art. Relative terms, such as “above,” “below,” “top,” “bottom,” “upper” and “lower” may be used to describe the various elements' relationships to one another, as illustrated in the accompanying drawings. These relative terms are intended to encompass different orientations of the device and/or elements in addition to the orientation depicted in the drawings. For example, if the device were inverted with respect to the view in the drawings, an element described as “above” another element, for example, would now be below that element. Where a first device is said to be connected or coupled to a second device, this encompasses examples where one or more intermediate devices may be employed to connect the two devices to each other. In contrast, where a first device is said to be directly connected or directly coupled to a second device, this encompasses examples where the two devices are connected together without any intervening devices other than electrical connectors (e.g., wires, bonding materials, etc.).
The disclosed embodiments relate generally to acoustic resonators comprising FBARs, DBARs, CRFs, and SMRs. For simplicity of explanation, several embodiments are described in the context of FBAR technologies; however, the described concepts can be adapted for use in other types of acoustic resonators. Certain details of acoustic resonators as well as related materials and methods of fabrication may be found in one or more of the following commonly owned U.S. Patents, Patent Application Publications and Patent Applications: U.S. Pat. No. 6,107,721, to Lakin; U.S. Pat. Nos. 5,587,620, 5,873,153 and 6,507,983 to Ruby, et al.; U.S. Pat. No. 7,629,865 to Ruby, et al.; U.S. Pat. No. 7,280,007 to Feng, et al.; U.S. Patent Application Publication No. 2007/0205850 to Jamneala, et al. now U.S. Pat. No. 8,981,876 B2; U.S. Pat. No. 7,388,454 to Richard C. Ruby, et al; U.S. Patent Application Publication No. 2010/0327697 to Choy, et al. now U.S. Pat. No. 8,248,185 B2; and U.S. Patent Application Publication No. 2010/0327994 to Choy, et al. now U.S. Pat. No. 8,902,023 B2 Examples of DBARs and CRFs as well as their materials and methods of fabrication, may be found in U.S. Pat. No. 7,889,024 to Paul Bradley et al., U.S. patent application Ser. No. 13/074,094 of Shirakawa et al., and filed on Mar. 29, 2011, U.S. patent application Ser. No. 13/036,489 of Burak et al., and filed on Feb. 28, 2011, U.S. patent application Ser. No. 13/074,262 to Burak, et al. filed on Mar. 29, 2011, U.S. patent application Ser. No. 13/101,376 of Burak et al., and filed on May 5, 2011, and U.S. patent application Ser. No. 13/161,946 to Burak, et al., and filed on Jun. 16, 2011. The disclosures of these patents, patent application publications and patent applications are specifically incorporated herein by reference. It is emphasized that the components, materials and method of fabrication described in these patents and patent applications are representative and other methods of fabrication and materials within the purview of one of ordinary skill in the art are contemplated.
In certain embodiments, an acoustic resonator comprises top and bottom electrodes, a piezoelectric layer formed between the top and bottom electrodes, and a collar structure formed around an active region defined by an overlap between top and bottom electrodes, and the piezoelectric layer, over an acoustic reflector (e.g., cavity depicted in
The collar structure is typically designed so that it has substantially the same cutoff frequency and modal distribution of a main non-propagating (evanescent mode, for instance) as the cutoff frequency and modal distribution of the piston mode in the active region. This prevents acoustic energy in the piston mode from being converted into unwanted propagating modes in regions of the collar structure and the main membrane. More particularly, it improves confinement of the piston mode within the active region while suppressing the excitation of spurious propagating lateral modes inside and outside of the active region. This, in turn, may reduce overall scattering loss and enhance the parallel resistance Rp of the acoustic resonator.
In the absence of the collar structure, there is a significant acoustic impedance discontinuity at the edge of the top electrode for an electrically excited piston mode. Because the electric field is also terminated at the edge of top electrode, that edge will cause both mechanical and electrical excitation of evanescent, propagating and complex modes supported by the structure. Evanescent and complex modes decay exponentially, so a wide enough collar structure will suppress them. Moreover, propagating modes may be suppressed by forming the collar structure with a proper width. Additionally, a collar structure extending over (or under) the top electrode may act as an integrated frame, thus it may minimize the amplitude of electrically excited piston mode before the top electrode edge and provide additional acoustic impedance discontinuities to suppress propagating modes.
Referring to
In
During typical operation as a part of a ladder filter, for instance, an input electrical signal may be applied to an input terminal of bottom electrode 415 and top electrode 430 may be connected to the output terminal. The input electrical signal typically comprises a time-varying voltage that causes vibration in the active region. This vibration in turn produces an output electrical signal at an output terminal of top electrode 430. The input and output terminals may be connected to bottom and top electrodes 415 and 430 via connection edges that extend away from the active region as shown in
In the absence of a collar structure and a top planarization layer, the electrically excited piston mode is terminated at the edge of top electrode 430. The top electrode edge presents a significant discontinuity in cutoff frequencies between the active region and the peripheral region outside of the edge of top electrode 430. For instance, in an illustrative simulated example, FBAR 400 vibrates with a cutoff frequency for thickness extensional (TE) mode of about 2 GHz in the active region and with a cutoff frequency for TE mode of about 3.5 GHz in the peripheral region to the left of top electrode 430. This structural discontinuity causes excitation of lateral modes in both the active and peripheral regions (to satisfy continuity of appropriate particle velocity and stress components at the interface between these both regions), leading in turn to undesirable scattering of acoustic energy from the piston mode and the resulting degradation of electrical response of FBAR 400.
Substrate 405 typically comprises a material compatible with semiconductor processes, such as silicon (Si), gallium arsenide (GaAs), indium phosphide (InP), glass, sapphire, alumina, or the like. Trench 410 is formed within substrate 405, and it functions to allow free mechanical vibration of an active region formed by an overlap between bottom electrode 415, top electrode 430, and piezoelectric layer 425 over trench 410. Trench 410 typically comprises an air gap, but it could alternatively comprise an acoustic mirror such as a Bragg mirror, for instance. Examples of various fabrication techniques of cavities in a substrate are described by U.S. Pat. No. 7,345,410 of Grannen et al., filed on Mar. 18, 2008, and various fabrication techniques of acoustic mirrors are described in U.S. Pat. No. 7,358,831 of Larson III, et al., filed Apr. 15, 2008, which are hereby incorporated by reference.
Substrate 405 has a trench 410, which can include an air gap or an acoustic reflector such as a Bragg mirror. The air gap or acoustic reflector is designed to prevent substrate 405 from absorbing mechanical energy from the acoustic stack as it vibrates. In other words, the air gap or acoustic reflector allows the active region of the acoustic stack to vibrate with relative freedom. The air gap is typically formed by depositing a sacrificial layer in trench 410 prior to forming bottom electrode 415, and then removing the sacrificial layer subsequent to forming top electrode 430. Thus, bottom electrode 415 can be suspended above the air gap.
Bottom and top electrodes 415 and 430 are typically formed of an electrically conductive metal such as molybdenum (Mo), tungsten (W), aluminum (Al) or copper (Cu), but other materials may be used in various alternative embodiments. In general, these features can be formed of the same or different materials and with the same or different thicknesses according to various design specifications or tradeoffs. Piezoelectric layer 425 typically comprises a thin film of piezoelectric material such as zinc oxide (ZnO), aluminum nitride (AlN) or lead zirconium titanate (PZT) but other materials may be used in various alternative embodiments.
Planarization layer 420 is typically formed of a planarization material such as non-etchable borosilicate glass (NEBSG). This layer is not strictly required for the functioning of FBAR 400, but its presence can confer various benefits. For instance, the presence of bottom planarization layer 420 tends to improve the structural stability of FBAR 400, it can improve the quality of growth of subsequent layers, and it may allow bottom electrode 415 to be formed without its edges extending beyond trench 410. Further examples of potential benefits of planarization are presented in U.S. patent application Ser. No. 13/286,038 filed Oct. 31, 2011, the subject matter of which is hereby incorporated by reference.
As indicated above, the performance of FBAR 400 can be degraded significantly by discontinuities of cutoff frequencies between the active and peripheral regions. One way to reduce the impedance discontinuities in FBAR 400 is to form a collar structure in the peripheral region to create a more uniform impedance profile for electrically excited purely longitudinal piston mode. The collar structure comprises a dielectric material of predetermined thickness and width that substantially surrounds the active region. The collar structure provides mass loading to lower the cutoff frequency outside the active region. Consequently, it may produce a more uniform lateral cutoff frequency profile across FBAR 400.
Referring to
Planarization layer 505 is typically formed of NEBSG or another suitable planarization material. Planarization layer 505 typically has a relatively low acoustic impedance, but it could alternatively be formed of a material having higher acoustic impedance than NEBSG in order to produce a vertical modal energy distribution across the stack in the region of collar structure 510 that matches more closely a vertical modal energy distribution across the stack in the active region, as will be described in relation to
Collar structure 510 is formed of a dielectric material, typically one with relatively high acoustic impedance. For example, it may be formed of silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, zinc oxide or diamond. Collar structure 510 can be formed by depositing a thin etch stop layer (e.g., 300 Å of AlN if silicon carbide is used to form a collar) and then depositing a layer of the collar dielectric layer over planarization layer 505 and top electrode 430. Then, dry etching is used to define a desired pattern of collar structure 510. After collar structure 510 is formed, an optional passivation layer may be deposited (not shown in
Referring to
The use of a high acoustic impedance material in planarization layer 505 tends to produce a vertical modal energy distribution across the stack in the region of collar structure 510 that matches more closely a vertical modal energy distribution across the stack in the active region. This allows a closer match between a vertical distribution of the electrically excited piston mode in the active region and a vertical distribution of an evanescent thickness extensional (eTE) mode in the region of collar structure 510 at the frequencies above the series resonance frequency Fs of FBAR 500B. The eTE mode may then decay exponentially in the direction away from the collar/membrane interface without coupling to other propagating modes supported by the FBAR 500B structure. This in turn may result in overall reduced scattering loss in the collar region and may produce significant improvements in Rp. Moreover, although not shown in
Referring to
A frame typically comprises one or more added (or removed) thin layers of material along a perimeter of a resonator device. It can lower (or increase) the cutoff frequency in a corresponding frame region relative to the main membrane. This in turn reduces the amplitude of the electrically excited piston mode and the resulting scattering at top electrode edges above (or below) the cut-off frequency of a membrane. Frames can also create an acoustic impedance mismatch to enable suppression of the amplitudes of propagating and/or evanescent modes (whichever exist in the frequency range of interest) mechanically excited at the membrane/frame boundary, thus further reducing acoustic energy leakage to the outside of the active region.
In relation to
Referring to
The graph of
In
A first set of curves C1 and C4 corresponds to FBAR 400 of
A second set of curves C2 and C5 corresponds to NPSE distribution and Za, respectively, of FBAR 500A in which top planarization layer 505 and collar structure 510 are formed of sputtered silicon carbide (SiC) and an intervening passivation layer is formed of AlN (“the second FBAR”). As indicated above, the collar thickness is about 4250 Å, and the FBAR device has a simulated Rp value of about 3700 Ohms for optimized width of collar structure 510.
A third set of curves C3 and C6 corresponds to NPSE distribution and Za FBAR 500A in which top planarization layer 505 is formed of NEBSG, the passivation layer is formed of ALN, and collar structure 510 is formed of sputtered SiC (“the third FBAR”). As indicated above, the collar thickness is about 3800 Å, and the FBAR device has a simulated Rp value of about 1950 Ohms for optimized width of collar structure 510.
As illustrated by curve C1, the electrically excited piston mode in active part of FBAR 500A has a very symmetric distribution across the stack with peak energy located in the middle of AlN layer. Not illustrated in
In general, improving match of modal distributions between exciting and specific excited modes (for instance, evanescent TE mode) results in increased excitation of these specific excited modes. As illustrated by curves C2 and C3, the NPSE distribution in evanescent TE mode for second FBAR 500A (curve C2) more closely resembles NPSE distribution for piston mode than NPSE distribution in evanescent TE mode for third FBAR 500A (curve C3). Thus, the second FBAR 500A (curve C2) has approximately two times higher Rp than the third FBAR 500A (curve C3). It should be pointed out, however, that a more rigorous analysis of modal mechanical excitation process requires calculation of overlap integrals between appropriate stress and particle velocity components on both sides of membrane/collar interface, so comparison of NPSE distributions in
The first FBAR does not support evanescent modes in the region beyond the top electrode 430 for frequency range of the pass-band of FBAR 400. Therefore significant amount of energy from the piston mode (curve C1) may be transferred to propagating modes supported by the stack comprising of bottom electrode 415 and piezoelectric layer 425, illustratively shown on the left side of line 702 in
Although the NPSE distribution of the eTE mode in the region of collar structure 510 of the second FBAR still differs significantly from NPSE distribution of the piston mode in the active region, the second FBAR has a significantly higher Rp value than the first FBAR (approximately three times larger). Also, the considerably higher Rp value of the second FBAR than the third FBAR can be attributed, at least in part, to the fact that the SiC forming the planarization layer has greater acoustic impedance than NEBSG. This difference in acoustic impedances is illustrated by a difference between curves C5 and C6 in the planarization layer region, that is a region between vertical lines 702 and 703 in
Referring to
A circle 815 indicates the maximum value of Rp, and horizontal arrows extending from the circle indicate other local maxima located nearby. The position of these local maxima indicates that Rp may be a periodic function of the width of collar structure 510, with a period of about 2.5 μm. In the region of circle 815, FBAR 500A exhibits an Rp value of about 5300 Ohms and a Kt2 value of about 5.95%. By comparison, FBAR 400, which lacks collar structure 510, exhibits an Rp value of about 1300 Ohms and a Kt2 value of about 5.87%. Accordingly, collar structure of appropriate width and height can produce a significantly improved Rp without diminishing Kt2. The specific dependence of Rp on the height and width of collar structure 510 may depend on actual stack thicknesses and materials used for FBAR 500A, as well as the design parameters of planarization layer 505 and collar structure 510. It should be pointed out that in the illustrative example shown in
Referring to
A first curve C1 illustrates the Q-factor of FBAR 400, and a second curve C2 illustrates the Q-factor of FBAR 500A. A third curve C3 illustrates the Rp value of FBAR 400, and a fourth curve C4 illustrates the Rp value of FBAR 500A.
A peak value of the Q-factor occurs for each of the devices at about 1.989 GHz. This frequency corresponds to the series resonance frequency Fs of the respective devices. Similarly, a peak value of Rp occurs for each of the two devices at about 2.041 GHz. This frequency corresponds to the parallel resonance frequency Fp of the respective devices. The bandwidth of these devices corresponds to the range of frequencies between their respective values of Fs and Fp. Accordingly, in this example, the two devices have similar bandwidths.
As illustrated by a double headed arrow, at frequencies above Fs, FBAR 500A has significantly higher Q-factor than FBAR 400. In addition, as illustrated by the respective peaks of third and fourth curves C3 and C4, FBAR 500A has a significantly higher Rp value than FBAR 400. In particular, FBAR 500A has an Rp value of about 4400 Ohms while FBAR 400 has an Rp value of about 1300 Ohms. As should be appreciated by one of ordinary skill in the art, Rp of FBAR 500A increased by approximately three times without any significant degradation of the bandwidth when compared to FBAR 400.
Referring to
Collar/frame structure 1005 extends into a region below the outer edges of top electrode 430 (i.e., into the active region). This extended part constitutes a frame portion of the combined collar/frame structure, and a remaining part constitutes a collar portion.
Collar/frame structure 1005 is typically formed by a relatively thin layer of carbon doped silicon oxide (CDO), although other materials may be used in various alternative embodiments. The use of a relatively thin layer, as opposed to a thicker layer, tends to improve the quality piezoelectric layer 425 grown over it. The use of a relatively low acoustic impedance material such as CDO allows the structure to achieve a relatively large frequency shift for relatively small thicknesses of the collar/frame layer. Typically, collar/frame 1005 layer is deposited following deposition and formation of bottom electrode 415 and planarization 420 layers. Dry etch is used to form a desired pattern of collar/frame 1005 region followed by deposition of piezoelectric layer 425.
In the example of
Because the edge of top electrode 430 is located at a distance of 5 μm from the side of trench 410, narrower versions of collar/frame structure 1005 (e.g., those that are less than 5 μm wide) do not necessarily extend under top electrode 430 forming a frame, or do not necessarily extend beyond the edge of electrode 430 forming a collar structure. Line 1105 in the contour plot of
In
Although
In the respective examples of
In each of
In
In
As illustrated by
Referring to
However, because collar 1405 is located substantially below the bottom electrode, it may be formed of metal rather than dielectric layer. Notably, there are two advantages of using metal layer to form collar 1405. First, some metal materials have generally significantly higher acoustic impedance than dielectric materials (molybdenum or tungsten, for example), so matching of modal distributions in the active region and collar 1405 regions of FBAR 1400 may be improved, yielding possible further improvements in Rp and Q-factor values. Second, metal collar 1405 may form a current redistribution layer which may result in lower electrical contribution to series resistance Rs of FBAR 1405.
Referring to
In the above-described embodiments, collar structures and collar/frame structures can generally be formed using conventional processing techniques, with examples including various forms of deposition, etching, polishing, and so on. Moreover, the described embodiments and related methods of fabrication can be modified in various ways as will be apparent to those skilled in the art. While example embodiments are disclosed herein, one of ordinary skill in the art appreciates that many variations that are in accordance with the present teachings are possible and remain within the scope of the appended claims. For instance, one type of variation may involve combining collars in different layers, or collar/frames in some layers with collars in other layers. Another example type of variation may involve adjustment to various parameters such as the widths of the collars in different layers or forming collars which do not enclose completely the FBAR structure, for example. Yet another type of variation may involve collars or collar/frames formed directly on top of piezoelectric layer without planarization layer 505 shown in
Number | Name | Date | Kind |
---|---|---|---|
4633285 | Hunsinger et al. | Dec 1986 | A |
4916520 | Kurashima | Apr 1990 | A |
4933743 | Thomas et al. | Jun 1990 | A |
5006478 | Kobayashi et al. | Apr 1991 | A |
5087959 | Omori et al. | Feb 1992 | A |
5587620 | Ruby et al. | Dec 1996 | A |
5698928 | Mang et al. | Dec 1997 | A |
5817446 | Lammert | Oct 1998 | A |
5825092 | Eelgado et al. | Oct 1998 | A |
5873153 | Ruby et al. | Feb 1999 | A |
6107721 | Lakin | Aug 2000 | A |
6291931 | Lakin | Sep 2001 | B1 |
6384697 | Ruby | May 2002 | B1 |
6396200 | Misu et al. | May 2002 | B2 |
6424237 | Ruby et al. | Jul 2002 | B1 |
6507983 | Ruby et al. | Jan 2003 | B1 |
6548943 | Kaitila et al. | Apr 2003 | B2 |
6607934 | Chang et al. | Aug 2003 | B2 |
6617751 | Sunwoo et al. | Sep 2003 | B2 |
6709776 | Noguchi et al. | Mar 2004 | B2 |
6864619 | Aigner et al. | Mar 2005 | B2 |
6985051 | Nguyen et al. | Jan 2006 | B2 |
7199683 | Thalhammer | Apr 2007 | B2 |
7233218 | Park et al. | Jun 2007 | B2 |
7275292 | Ruby et al. | Oct 2007 | B2 |
7280007 | Feng et al. | Oct 2007 | B2 |
7345410 | Grannen et al. | Mar 2008 | B2 |
7358831 | Larson, III et al. | Apr 2008 | B2 |
7377168 | Liu | May 2008 | B2 |
7388454 | Ruby et al. | Jun 2008 | B2 |
7459990 | Wunnicke et al. | Dec 2008 | B2 |
7466213 | Lobl et al. | Dec 2008 | B2 |
7486213 | Yu et al. | Feb 2009 | B2 |
7575292 | Furukawa | Aug 2009 | B2 |
7629865 | Ruby | Dec 2009 | B2 |
7642693 | Akiyama et al. | Jan 2010 | B2 |
7889024 | Bradley et al. | Feb 2011 | B2 |
7965019 | Gabl et al. | Jun 2011 | B2 |
7986198 | Nakatsuka et al. | Jul 2011 | B2 |
8008993 | Milsom et al. | Aug 2011 | B2 |
8030823 | Sinha et al. | Oct 2011 | B2 |
8253513 | Zhang | Aug 2012 | B2 |
8330325 | Burak et al. | Dec 2012 | B1 |
8507919 | Ishikura | Aug 2013 | B2 |
8575820 | Shirakawa et al. | Nov 2013 | B2 |
8872604 | Burak | Oct 2014 | B2 |
8896395 | Burak et al. | Nov 2014 | B2 |
20010026951 | Vergani et al. | Oct 2001 | A1 |
20020153965 | Ruby et al. | Oct 2002 | A1 |
20030132493 | Kang et al. | Jul 2003 | A1 |
20040046622 | Aigner et al. | Mar 2004 | A1 |
20040056735 | Nomura et al. | Mar 2004 | A1 |
20040092234 | Pohjonen | May 2004 | A1 |
20040099898 | Grivna et al. | May 2004 | A1 |
20040124952 | Tikka | Jul 2004 | A1 |
20040129079 | Kato et al. | Jul 2004 | A1 |
20040150293 | Unterberger | Aug 2004 | A1 |
20040150296 | Park et al. | Aug 2004 | A1 |
20040166603 | Carley | Aug 2004 | A1 |
20040195937 | Matsubara et al. | Oct 2004 | A1 |
20040212458 | Lee | Oct 2004 | A1 |
20040246075 | Bradley et al. | Dec 2004 | A1 |
20040257171 | Park et al. | Dec 2004 | A1 |
20040257172 | Schmidhammer et al. | Dec 2004 | A1 |
20040263287 | Ginsburg et al. | Dec 2004 | A1 |
20050012570 | Korden et al. | Jan 2005 | A1 |
20050012716 | Mikulin et al. | Jan 2005 | A1 |
20050023931 | Bouche et al. | Feb 2005 | A1 |
20050030126 | Inoue et al. | Feb 2005 | A1 |
20050036604 | Scott | Feb 2005 | A1 |
20050057117 | Nakatsuka et al. | Mar 2005 | A1 |
20050057324 | Onishi et al. | Mar 2005 | A1 |
20050068124 | Stoemmer | Mar 2005 | A1 |
20050082626 | Leedy | Apr 2005 | A1 |
20050093396 | Larson, III et al. | May 2005 | A1 |
20050093653 | Larson, III | May 2005 | A1 |
20050093654 | Larson, III et al. | May 2005 | A1 |
20050093655 | Larson, III et al. | May 2005 | A1 |
20050093657 | Larson, III et al. | May 2005 | A1 |
20050093658 | Larson, III et al. | May 2005 | A1 |
20050093659 | Larson, III et al. | May 2005 | A1 |
20050104690 | Larson, III et al. | May 2005 | A1 |
20050110598 | Larson, III | May 2005 | A1 |
20050128030 | Larson, III et al. | Jun 2005 | A1 |
20050140466 | Larson, III et al. | Jun 2005 | A1 |
20050167795 | Higashi | Aug 2005 | A1 |
20050193507 | Ludwiczak | Sep 2005 | A1 |
20050206271 | Higuchi et al. | Sep 2005 | A1 |
20050206483 | Pashby et al. | Sep 2005 | A1 |
20050275486 | Feng et al. | Dec 2005 | A1 |
20060081048 | Mikado et al. | Apr 2006 | A1 |
20060087199 | Larson, III et al. | Apr 2006 | A1 |
20060103492 | Feng et al. | May 2006 | A1 |
20060119453 | Fattinger et al. | Jun 2006 | A1 |
20060121686 | Wei et al. | Jun 2006 | A1 |
20060125489 | Feucht et al. | Jun 2006 | A1 |
20060132262 | Fazzio et al. | Jun 2006 | A1 |
20060160353 | Gueneau de Mussy et al. | Jul 2006 | A1 |
20060164183 | Tikka et al. | Jul 2006 | A1 |
20060185139 | Larson, III et al. | Aug 2006 | A1 |
20060197411 | Hoen et al. | Sep 2006 | A1 |
20060238070 | Costa et al. | Oct 2006 | A1 |
20060284707 | Larson, III et al. | Dec 2006 | A1 |
20060290446 | Aigner et al. | Dec 2006 | A1 |
20070035364 | Sridhar et al. | Feb 2007 | A1 |
20070080759 | Jamneala et al. | Apr 2007 | A1 |
20070084964 | Sternberger | Apr 2007 | A1 |
20070085213 | Anh et al. | Apr 2007 | A1 |
20070085447 | Larson, III et al. | Apr 2007 | A1 |
20070085631 | Larson, III et al. | Apr 2007 | A1 |
20070085632 | Larson, III et al. | Apr 2007 | A1 |
20070086274 | Nishimura et al. | Apr 2007 | A1 |
20070090892 | Larson, III et al. | Apr 2007 | A1 |
20070170815 | Unkrich | Jul 2007 | A1 |
20070171002 | Unkrich | Jul 2007 | A1 |
20070176710 | Jamneala et al. | Aug 2007 | A1 |
20070205850 | Jamneala et al. | Sep 2007 | A1 |
20080055020 | Handtmann et al. | Mar 2008 | A1 |
20080179995 | Umeda | Jul 2008 | A1 |
20080258842 | Ruby et al. | Oct 2008 | A1 |
20080297279 | Thalhammer et al. | Dec 2008 | A1 |
20080297280 | Thalhammer et al. | Dec 2008 | A1 |
20090064498 | Mok et al. | Mar 2009 | A1 |
20090096550 | Handtmann et al. | Apr 2009 | A1 |
20090102319 | Nakatsuka et al. | Apr 2009 | A1 |
20100039000 | Milson et al. | Feb 2010 | A1 |
20100052176 | Kamada et al. | Mar 2010 | A1 |
20100102358 | Lanzieri et al. | Apr 2010 | A1 |
20100148637 | Satou | Jun 2010 | A1 |
20100327697 | Choy et al. | Dec 2010 | A1 |
20100327994 | Choy et al. | Dec 2010 | A1 |
20110092067 | Bonilla et al. | Apr 2011 | A1 |
20110121916 | Barber et al. | May 2011 | A1 |
20110180391 | Larson, III et al. | Jul 2011 | A1 |
20110204996 | Gilbert et al. | Aug 2011 | A1 |
20110266917 | Metzger et al. | Nov 2011 | A1 |
20110266925 | Ruby et al. | Nov 2011 | A1 |
20120177816 | Larson, III et al. | Jul 2012 | A1 |
20120218055 | Burak | Aug 2012 | A1 |
20120218056 | Burak | Aug 2012 | A1 |
20120218060 | Burak et al. | Aug 2012 | A1 |
20120248941 | Shirakawa et al. | Oct 2012 | A1 |
20130003377 | Sakai et al. | Jan 2013 | A1 |
20130038408 | Burak et al. | Feb 2013 | A1 |
20130082799 | Zuo et al. | Apr 2013 | A1 |
20130106534 | Burak | May 2013 | A1 |
20130127300 | Umeda et al. | May 2013 | A1 |
20130155574 | Doolittle | Aug 2013 | A1 |
20130205586 | Takada et al. | Aug 2013 | A1 |
20130221454 | Dunbar et al. | Aug 2013 | A1 |
20130235001 | Yun et al. | Sep 2013 | A1 |
20130241673 | Yokoyama et al. | Sep 2013 | A1 |
20130314177 | Burak et al. | Nov 2013 | A1 |
20130334625 | Lin | Dec 2013 | A1 |
20140111288 | Nikkel et al. | Apr 2014 | A1 |
20140118087 | Burak et al. | May 2014 | A1 |
20140118088 | Burak et al. | May 2014 | A1 |
20140118091 | Burak et al. | May 2014 | A1 |
20140118092 | Burak et al. | May 2014 | A1 |
20140159548 | Burak et al. | Jun 2014 | A1 |
20140224941 | Gitter | Aug 2014 | A1 |
20140225682 | Burak | Aug 2014 | A1 |
Number | Date | Country |
---|---|---|
101170303 | Apr 2008 | CN |
0880227 | Nov 1998 | EP |
10173479 | Jun 1998 | JP |
2003-017964 | Jan 2003 | JP |
2007208845 | Aug 2007 | JP |
2008211394 | Sep 2008 | JP |
1471443 | Jun 2010 | JP |
20020050729 | Jun 2002 | KR |
1020030048917 | Jun 2003 | KR |
WO9937023 | Jul 1999 | WO |
WO2005043752 | May 2005 | WO |
WO2006079353 | Aug 2006 | WO |
2007085332 | Aug 2007 | WO |
WO2013065488 | May 2013 | WO |
Entry |
---|
“Co-pending U.S. Appl. No. 13/662,425, filed Oct. 27, 2012”. |
“Co-pending U.S. Appl. No. 13/662,460, filed Oct. 27, 2012”. |
“Co-pending U.S. Appl. No. 13/766,993, filed Feb. 14, 2013”. |
“Co-pending U.S. Appl. No. 13/767,754, filed Feb. 14, 2013”. |
“Co-pending U.S. Appl. No. 13/955,744, filed Jul. 31, 2013”. |
Aigner, Robert , “SAW, BAW And The Future Of Wireless”, May 6, 2013, pp. 1-4 May 6, 2013. |
El Hassan, M. et al, “Techniques For Tuning BAW-SMR Resonators For The 4th Generation Of Mobile Communications”, lntech 2013 , 421-442. |
Pineda, Humberto , “Thin-Film Bulk Acoustic Wave Resonators—FBAR”, Bellaterra, Monpelier Dec. 2007 , 1-241. |
Co-pending U.S. Appl. No. 13/074,094, filed Mar. 29, 2011. |
Co-pending U.S. Appl. No. 13/036,489, filed Feb. 28, 2011. |
Co-pending U.S. Appl. No. 13/074,262, filed Mar. 29, 2011. |
Co-pending U.S. Appl. No. 13/101,376, filed May 5, 2011. |
Co-pending U.S. Appl. No. 13/161,946, filed Jun. 16, 2011. |
Co-pending U.S. Appl. No. 13/286,038, filed Oct. 31, 2011. |
Lee, et al. “Development of High-Quality FBAR Devices for Wireless Applications Employing Two-Step Annealing Treatments”, IEEE Microwave and Wireless Components Letters, vol. 21, No. 11, Nov. 2011. |
“Co-pending U.S. Appl. No. 13/654,718, filed Oct. 18, 2012”. |
“Co-pending U.S. Appl. No. 13/658,024, filed Oct. 23, 2012”. |
“Co-pending U.S. Appl. No. 13/660,941, filed Oct. 25, 2012”. |
“Co-pending U.S. Appl. No. 13/663,449, filed Oct. 29, 2012”. |
G.W. Archibald “Experimental results of bulk acoustic wave transverse graded electrode patterns”, Proceedings of the 1998 IEEE International Frequency Control Symposium, Publication Year: 1998 , pp. 477-483. |
Kazuhiko Kano, et al., “Enhancement of Piezoelectric Response in Scandium Aluminum Nitride Alloy Thin Films prepared by Dual Reactive Co-Sputtering”, vol. 17, 2012. |
Milena Moriera, et al. “Aluminum scandium nitride thin-film bulk acoustic resonators for wide band applications”, Vacuum 86 (2011) 23-26. |
Kerherve, “BAW Technologies for Radiofrequency Filters and Duplexers”, Nov. 2011. |
Lin, “Temperature Compensation of Aluminum Nitride Lamb Wave Resonators Utilizing the Lowest-Order Symmetric Mode”, Electrical Engineering and Computer Sciences University of California at Berkeley, Dec. 14, 2012. |
Umeda et al, “Piezoelectric Properties of ScAlN Thin Films for PIEZO-MEMS Devices”, MEMS 2013, Taipei, Taiwan, Jan. 20-24, 2013, pp. 733-736. |
Machine translation of WO2006079353. |
Machine translation of WO2013065488. |
Office Action mailed Jan. 28, 2015 in U.S. Appl. No. 13/658,024. |
Machine translation of JP2003-017964. |
Machine translation of CN101170303. |
A.C. Lynch, “Precise measurements on dielectric and magnetic materials”, IEEE Transactions on Instrumentation and Measurement, vol. IM-23, No. 4, Dec. 1974, p. 425-431. |
Office Action mailed Mar. 6, 2015 in U.S. Appl. No. 13/781,491. |
Machine translation of WO2007085332, published Aug. 2, 2007. |
English abstract of JP4471443, published Jun. 2, 2010. |
Pensala, “Thin Film Bulk Acoustic Wave Devices: Performance Optimization and Modeling”, VTT Publications 756, http://www.vtt.fi.inf/pdf/publications/2011/P756.pdf, Feb. 25, 2011, 1-108. |
Tang, et al., “Micromachined Bulk Acoustic Resonator With A Raised Frame”, 16th International Conference on Mechatronics Technology, Oct. 16-19, 2012, Tianjin, China. |
Pandey, et al., “Anchor Loss Reduction in Resonant MEMS using MESA Structures”, Proceedings of the 2nd IEEE International Conference on Nano/Micro Engineered and Molecular Systems, Bangkok, Thailand Jan. 16-19, 2007, 380-885. |
Tas, et al., “Reducing Anchor Loss in Micromechanical Extensional Mode Resonators”, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, vol. 57, No. 2. Feb. 2010, 448-454. |
Machine translation of JP2007208845, published Aug. 16, 2007. |
Machine translation of JP2008211394, published Sep. 11, 2008. |
IEEE Xplore Abstract for Suppression of Acoustic Energy Leakage in FBARs with Al Bottom Electrode: FEM Simulation and Experimental Results, 2007 IEEE Ultrasonics Symposium, Oct. 28-31, 2007, 1657-1660. |
Ohara, et al., “Suppression of Acoustic Energy Leakage in FBARs with Al Bottom Electrode: FEM Simulation and Experimental Results”, 2007 IEEE Ultrasonics Symposium, Oct. 28-31, 2007, 1657-1660. |
Number | Date | Country | |
---|---|---|---|
20140118091 A1 | May 2014 | US |