Resonator with a staggered electrode configuration

An integrated circuit device includes a piezoelectric substrate having a first surface and a second surface opposite the first surface. The device also includes a first electrode and a second electrode on the first surface of the piezoelectric substrate, the first electrode having a first width and the second electrode having a second width. The device further includes a third electrode and a fourth electrode on the second surface of the piezoelectric substrate, the third electrode having a third width that is substantially the same as the second width, and the fourth electrode having a fourth width that is substantially the same as the first width. The first and third electrodes operate as part of a first portion of a microelectromechanical systems (MEMS) resonator, and the second and fourth electrodes operate as part of a second portion of the MEMS resonator.

TECHNICAL FIELD

The present disclosure generally relates to integrated circuits (ICs). More specifically, one aspect of the present disclosure relates to a resonator with a staggered electrode configuration.

BACKGROUND

Filters or other devices implemented in integrated circuits may use components known as resonators to generate resonant frequencies. Resonators, however, may experience the problem of spurious responses. A spurious response is any unwanted signal on a frequency other than the resonant frequency (e.g., the frequency being broadcast or received). Devices experiencing spurious frequency responses operate in spurious mode. A resonator that operates in the spurious mode creates noise and other problems in the overall circuit design of the filter, or any other device that incorporates the resonator.

The mismatch between the coefficients of thermal expansion of multiple materials making up a resonator may lead to excessive thermal stress. Undue amounts of thermal stress leads to stress imbalance, which may result in problems such as beam buckling, damage to the resonator structure, or other spurious mode irregularities.

Resonators may be acoustically coupled such that the electrical signals transmitted through the resonator are transferred electromechanically. Resonators may also extend in a lateral fashion, or be horizontally constructed. Often, such horizontal resonators have components, such as electrodes, that are symmetrically structured. Resonators may also be symmetrical and arranged in a horizontal structure, or implemented in microelectromechanical systems (MEMS). Nevertheless, such MEMS resonators may experience problems such as spurious responses, operation in the spurious mode, or thermal stress, as discussed above.

SUMMARY

In one aspect of the present disclosure, an integrated circuit device includes a piezoelectric substrate having a first surface and a second surface opposite the first surface. The device also includes a first electrode and a second electrode on the first surface of the piezoelectric substrate. The first electrode has a first width and the second electrode has a second width different from the first width. The device further includes a third electrode and a fourth electrode on the second surface of the piezoelectric substrate. The third electrode has a third width that is substantially the same as the second width. The fourth electrode has a fourth width that is substantially the same as the first width. The first electrode and the third electrode are arranged to operate as a first portion of a microelectromechanical systems (MEMS) resonator, and the second electrode and the fourth electrode are arranged to operate as a second portion of the MEMS resonator.

In another aspect, an integrated circuit device including means for supporting having a first surface and a second surface opposite the first surface. The device also includes a first electrode and a second electrode on the first surface of the supporting means, the first electrode having a first width and the second electrode having a second width different from the first width. The device further includes a third electrode and a fourth electrode on the second surface of the supporting means. The third electrode has a third width that is substantially the same as the second width. The fourth electrode has a fourth width that is substantially the same as the first width. The first electrode and the third electrode are arranged to operate as a first portion of a microelectromechanical systems (MEMS) resonator. The second electrode and the fourth electrode are arranged to operate as part of a second portion of the MEMS resonator.

In a further aspect, a method includes fabricating a first electrode of a first width and a second electrode of a second width on a first surface of a piezoelectric substrate. The second width of the second electrode is different from the first width of the first electrode. The method further includes fabricating a third electrode of a third width substantially the same as the second width, and fabricating a fourth electrode of a fourth width, substantially the same as the first width, on a second surface of the piezoelectric substrate opposite the first surface. The first electrode and the third electrode are arranged as a first aligned portion of a microelectromechanical systems (MEMS) resonator. The second electrode and the fourth electrode are arranged as a second aligned portion of the MEMS resonator.

DETAILED DESCRIPTION

Resonators can be used as oscillators or as components within a filter to achieve high order frequencies. Acoustically coupled resonators are resonators in which the electrical signals flowing through the resonator are transferred acoustically or electromechanically. Many resonators are also implemented in microelectromechanical systems (MEMS). Resonators generally experience the problem of spurious responses. That is, signals at frequencies other than the resonant frequency appear in the frequency response of the resonator. This is particularly undesirable in a filter, where unwanted frequencies interfere with the filter's operation. If spurious responses continue to occur, the resonator operates in a spurious mode.

Operating in the spurious mode over time drastically reduces the quality factor, Q, and the insertion loss of a resonator, and can also lead to problems caused by thermal stress such as stress imbalance. Stress imbalance is caused by the mismatch between coefficients of thermal expansion (CTE) of different materials making up a resonator. Stress imbalance can also lead to problems such as beam buckling, which alters and deforms the structure of the resonator.

In one aspect of the disclosure, a resonator with a staggered electrode configuration is disclosed. The staggered electrodes are positioned on opposite surfaces of a piezoelectric substrate of the resonator to reduce spurious response, suppress the spurious mode and prevent problems such as stress imbalance from happening. In one configuration, the widths of the electrodes on one surface of the piezoelectric substrate are balanced with the widths of the electrodes on another surface of the piezoelectric substrate so that problems such as spurious mode and stress imbalance do not occur.

For example, a device includes a piezoelectric substrate, which may have a first surface and a second surface opposite the first surface. The device also includes a first electrode and a second electrode on the first surface of the piezoelectric substrate, the first electrode having a first width and the second electrode having a second width. The device further includes a third electrode and a fourth electrode on the second surface of the piezoelectric substrate, the third electrode having a third width that is substantially the same as the second width, and the fourth electrode having a fourth width that is substantially the same as the first width. The first and third electrodes operate as part of a first portion of a microelectromechanical systems (MEMS) resonator, and the second and fourth electrodes operate as part of a second portion of the MEMS resonator. The first portion of the MEMS resonator may be aligned somehow, and the second portion of the MEMS resonator may be aligned in order to balance out the entire resonator.

Furthermore, if an electrode with a larger size, width or weight is placed on one side (e.g., the right side) of the first surface of the piezoelectric substrate, another electrode with a substantially similar size, width or weight as this electrode may be placed on the opposite side (e.g., the left side) of the second surface of the piezoelectric substrate for balancing purposes. The same applies for electrodes with smaller sizes, widths or weights.

FIG. 1Ais a cross-sectional view of an ideal resonator100. The ideal resonator100cannot be achievable in the real world because every component has to be almost perfectly aligned. The ideal resonator100also contains a substrate102. In addition, a first electrode P1has a width W1that is equivalent to a width W2of a second electrode P2. Corresponding ground terminals GND and GND′ also share the widths W1and W2, respectively, of the first and second electrodes P1and P2. The first overhang distance OH1(e.g., the distance from the left edge of the first electrode P1to the left edge of the substrate102) is also the same as the second overhang distance OH2(e.g., the distance from the right edge of the second electrode P2to the right edge of the substrate102). A gap G between the first electrode P1and the second electrode P2is also positioned at the exact middle of the substrate102so that the first and second electrodes P1and P2are perfectly aligned with respect to the center of the substrate102.

The ideal resonator100exhibits an insertion loss value of around 30 dB, with practically no spurious response. The ideal resonator100, however, is not achievable, or is very difficult to achieve. In reality, a typical resonator110, as shown inFIG. 1B, is misaligned when fabricated. Potential solutions that allow normal resonators to become as aligned as possible, in order to avoid spurious mode and achieve strong insertion loss, are described.

FIG. 1Bis a cross-sectional view illustrating the misalignment in a typical resonator110. The typical resonator110is the usual resonator that results from real world misalignment. As can be seen inFIG. 1B, the bottom left ground terminal GND is misaligned with the first electrode P1. The width W1′, or the width of the bottom left ground terminal GND is now not aligned with the width of the first electrode P1. Other components, such as the bottom right ground terminal GND′ and the second electrode P2, are also misaligned as a result of this misalignment with the typical resonator110.

The typical resonator110leads to spurious mode and spurious responses, which drastically reduces the Q factor of the resonator. The insertion loss is also reduced by nearly half when compared to a perfectly aligned resonator such as the ideal resonator100ofFIG. 1A. In one configuration, the insertion loss of the typical resonator110is roughly lower than or around 15 dB.

FIG. 2Ais a cross-sectional view of another typical resonator200. The typical resonator200includes a potential misalignment compensation strategy used to solve the misalignment problem experienced by the typical resonator110inFIG. 1B. The typical resonator200shows two larger bottom ground electrodes GND and GND′. Therefore, the first ground terminal width W3(e.g., the width of the bottom left ground terminal GND) is large enough to encompass any possible shift from the first electrode P1. That is, the first electrode P1is within the width W3of ground terminal GND, even if the first electrode P1shifts or becomes misaligned. The same applies for the second ground terminal width W4(e.g., the width of the bottom right ground terminal GND′), which is large enough to encompass any possible shift from the second electrode P2.

Unfortunately, spurious mode is insignificantly suppressed by the implementation of the typical resonator200. As a result, the insertion loss of the typical resonator200is around 25 dB.

The typical resonator200can lead to the serious problem of stress imbalance. Stress imbalance is caused by a mismatch between the coefficients of thermal expansion (CTE) between the materials that make up a resonator's composition, (e.g., aluminum nitride (AlN) and molybdenum (Mo)). For example, the coefficient of thermal expansion for aluminum nitride is 4.6 parts per million per centigrade degree (ppm), and the coefficient of thermal expansion for molybdenum is 7.1 ppm.

The curvature, κ, of a system composed of a thin film of thickness hfdeposited on a much thicker substrate of thickness hscan be defined by equation (1) as follows:

Where σfis the film stress, hfis the film thickness, v is the substrate's Poisson ratio, hsis the substrate's thickness and E is the substrate's Young's modulus. Equation (1) can be applied to the typical resonator200, where larger bottom electrodes are used to compensate for any misalignment between the top electrodes. Due to the higher coefficient of thermal expansion (CTE) of the material within the bottom electrode, which is also wider (and usually molybdenum), the overall beam of the resonator becomes a convex bulge and looks “buckled up.” This beam buckling phenomena is shown inFIG. 2B.

FIG. 2Bis a three-dimensional view210of a typical resonator202that exhibits beam buckling. The typical resonator202is the typical resonator200after undergoing beam buckling. Three-dimensional view210shows the typical resonator202after experiencing beam buckling due to thermal stress imbalance and a mismatch between the materials making up the typical resonator202(e.g., aluminum nitride (AlN) and molybdenum (Mo)). This completely deforms the resonator beam and also ruins the structure of the resonator. In this example, the insertion loss experienced is around 15 dB or less at the point beam buckling occurs. There is also a spurious mode irregularity in the spurious response when beam buckling occurs.

FIG. 3is a perspective view of a staggered electrode resonator300, according to an aspect of the present disclosure. The staggered electrode resonator300includes a first electrode304having a first width314and a second electrode306having a second width316on a first surface of a substrate302. The staggered electrode resonator300also includes a third electrode308having a third width318and a fourth electrode310having a fourth width320on a second surface of the substrate302. A first portion curvature312ashows the curvature of a first portion of the staggered electrode resonator300buckling down. In addition, a second portion curvature312bshows the curvature of a second portion of the staggered electrode resonator300buckling up.

In one configuration, the first width314is substantially similar to or nearly the same as the fourth width320, and the second width316is substantially similar to or nearly the same as the third width318. In this configuration, staggering electrodes having substantially similar widths (and likely other similar properties) at opposite ends of opposite surfaces of a substrate, provides a balanced resonator that eliminates thermal stress issues and increases insertion loss. The resulting balanced structure of the staggered electrode resonator300is also an even, stable structure with very low stress.

In one configuration, if the first width314and the fourth width320can be expressed as W1, and the second width316and the third width318can be expressed as W2, then the following equation may be satisfied to achieve greater than 30 dB insertion loss or noise suppression: 0.2 μm<|W1−W2|<0.8 μm. In another configuration, the staggered electrode resonator300achieves an insertion loss of 35 dB or higher, which substantially exceeds the insertion loss achieved by the ideal resonator100ofFIG. 1A(e.g., by some estimates approaching 30 dB).

In one configuration, the staggered electrode resonator300is a microelectromechanical systems (MEMS) resonator. In this configuration, the first electrode304and the second electrode306are input and output, respectively, of the staggered electrode resonator300. In addition, the third electrode308and the fourth electrode310are ground electrodes of the staggered electrode resonator300. In another configuration, the first electrode304and the second electrode306are ground electrodes of the staggered electrode resonator300. In addition, the third electrode308and the fourth electrode310are input and output, respectively, of the staggered electrode resonator300. In another configuration, the first electrode304and the third electrode308are input and output, respectively, of the staggered electrode resonator300. In addition, the second electrode306and the fourth electrode310are ground electrodes of the staggered electrode resonator300. In another configuration, the first electrode304and the fourth electrode310are input and output, respectively, of the staggered electrode resonator300. In addition, the second electrode306and the third electrode308are ground electrodes. In another configuration, the second electrode306and the third electrode308are input and output, respectively, of the staggered electrode resonator300. In addition, the first electrode304and the fourth electrode310are ground electrodes.

In one configuration, there may be further electrodes such as a fifth electrode, a sixth electrode, a seventh electrode and an eighth electrode (e.g., having different width configurations) to balance out with the first electrode304, the second electrode306, the third electrode308and the fourth electrode310.

FIG. 4Ais a three-dimensional view400of a staggered electrode resonator402, according to an aspect of the present disclosure. As can be seen by the three-dimensional view400, the staggered electrode resonator402is a relatively even and stable structure with low thermal stress and no stress imbalance. Therefore, no beam buckling occurs in the staggered electrode resonator402. The staggered electrode resonator402may also be stronger and more robust than the typical resonator200shown inFIG. 2Aor the typical resonator202that incurs beam buckling inFIG. 2B.

FIG. 4Bis a more detailed perspective view of a staggered electrode resonator430, according to an aspect of the present disclosure. For the sake of explanation, microelectromechanical systems (MEMS) resonators are described, although the present disclosure applies to other types of resonators, as well. The staggered electrode resonator430includes a substrate302. In one configuration, the substrate302is made of piezoelectric materials such as aluminum nitride (AlN) and its alloys, such as those doped with boron (B), chromium (Cr), erbium (Er) or scandium (Sc); zinc oxide (ZnO); lithium niobate (LiNbO3), lithium tantalate (LiTaO3), lead zirconate titanate or PZT (Pb[ZrxTi1-x]O30≦x≦1), quartz (SiO4or SiO2) crystals, and topaz (Al2SiO4(F,OH)2) crystals. The substrate302may also be made of other like materials having a mechanical structure that can be stimulated in an electrical fashion through electromechanical coupling.

The staggered electrode resonator430has a first electrode304, a second electrode306, a third electrode308and a fourth electrode310. In one configuration, the first electrode304, the second electrode306, the third electrode308and the fourth electrode310are made of materials including molybdenum (Mo), platinum (Pt), copper (Cu), aluminum (Al), silver (Ag), gold (Au), tungsten (W), nickel (Ni), or other like conductive materials. A first signal404may be coupled to the first electrode304, and a second signal406may be coupled to the second electrode306. The first signal404is also coupled to the fourth electrode310, and the second signal406is also coupled to the third electrode308. In one configuration, the first signal404may be an electrical input signal and the second signal406may be an electrical output signal. The first electrode304, the second electrode306, the third electrode308and the fourth electrode310may be on any surface of the substrate302including top surfaces, bottom surfaces, and side surfaces.

Any of the electrodes304,306,308and310may be a ground terminal. In one configuration, the ground terminal is coupled to a voltage ground or source supply voltage (Vss). Each ground terminal may also be separated into two or more separate ground terminals, which can be positioned on any surface of the substrate302.

The staggered electrode resonator430operates via a first electrical field414, a first mechanical displacement412, a second mechanical displacement416and a second electrical field418. The first mechanical displacement412and the second mechanical displacement416represent directions of mechanical displacement that occur within the staggered electrode resonator430when signals are present on the electrodes. The first electrical field414and the second electrical field418represent the direction of the electrical field through the staggered electrode resonator430.

As can be seen byFIG. 4B, there are different directional freedoms for both the electrical field and the mechanical displacement. The first direction is expansion. That is, the first signal404(e.g., an input signal) is fed into the first electrode304(which may act as an input electrode), which generates the first electrical field414, which is then in turn translated into the first mechanical displacement412that flows outward and expands a region of the substrate302.

The second direction is contraction. That is, the second mechanical displacement416translates an inward, contracting mechanical displacement from a region of the substrate302into the second electrical field418, which flows into the second electrode306(which may act as an output electrode) and becomes dispelled as the second signal406(e.g., an output signal). The same process applies for the first signal404input into the fourth electrode310, and the second signal406output from the third electrode308. The transfer and translation of the electrical field to a mechanical displacement is due to the electromechanical coupling resonance caused by the piezoelectric effect.

The expansion and contraction directions counteract each other to maintain constant parameters in the staggered electrode resonator430, such as a constant resonant frequency. Also, by changing the position or width of the electrodes304,306,308and310on any surfaces of the substrate302, the parameters of the staggered electrode resonator430are modified and may be adjusted to meet particular design specifications.

In one configuration, the staggered electrode resonator430is a microelectromechanical systems (MEMS) resonator. In this configuration, the first electrode304and the second electrode306are input and output, respectively, of the staggered electrode resonator430. In addition, the third electrode308and the fourth electrode310are ground electrodes of the staggered electrode resonator430. In another configuration, the first electrode304and the second electrode306are ground electrodes of the staggered electrode resonator430. In addition, the third electrode308and the fourth electrode310are input and output, respectively, of the staggered electrode resonator430.

In another configuration, the first electrode304and the third electrode308are input and output, respectively, of the staggered electrode resonator430. In addition, the second electrode306and the fourth electrode310are ground electrodes of the staggered electrode resonator430. In another configuration, the first electrode304and the fourth electrode310are input and output, respectively, of the staggered electrode resonator430. In addition, the second electrode306and the third electrode308are ground electrodes of the staggered electrode resonator430. In another configuration, the second electrode306and the third electrode308are input and output, respectively, of the staggered electrode resonator430. In addition, the first electrode304and the fourth electrode310are ground electrodes of the staggered electrode resonator430.

In one configuration, there may be further electrodes such as a fifth electrode, a sixth electrode, a seventh electrode and an eighth electrode, each having different width configuration. The fifth electrode, a sixth electrode, a seventh electrode and an eighth electrode are arranged in balance with the first electrode304, the second electrode306, the third electrode308and the fourth electrode310, respectively. The staggered electrode resonator430may also be expanded in any direction where additional electrodes may be added. The staggered electrode resonator430may also add on additional fingers or electrodes to the overall structure.

The staggered electrode resonator430also contains a first electrode thickness432, a substrate thickness408, a fourth electrode thickness410, a fourth electrode width422and a substrate width420. Example values for the first electrode thickness432and the fourth electrode thickness410may range from about 100 nm to 400 nm. Example values for the substrate thickness408may range from about 0.5 μm to 5 μm. Example values for the fourth electrode width422may range from about 300 nm to 1.2 μm. Example values for the substrate width420may range from about 1.5 μm to 15 μm.

In one configuration, the first electrode thickness432is substantially similar to the fourth electrode thickness410. In another configuration, the first electrode thickness432and the fourth electrode thickness410is the thickness of a molybdenum (Mo) layer. In one configuration, the substrate thickness408is the thickness of an aluminum nitride (AlN) layer. In this configuration, the substrate width420is the thickness of an aluminum nitride (AlN) layer.

FIG. 5is a process flow diagram illustrating a process500of fabricating a staggered electrode resonator according to an aspect of the present disclosure. In block502, a first electrode (e.g., the first electrode304) of a first width (e.g., the first width314) and a second electrode (e.g., the second electrode306) of a second width (e.g., the second width316) are fabricated on a first surface of a piezoelectric substrate (e.g., the substrate302). In block504, a piezoelectric material layer is deposited on the first surface of the piezoelectric substrate. In block506, the piezoelectric material layer is patterned. Blocks504and506are shown with dotted line borders to indicate that they may be optionally performed in process500.

In block508, a third electrode (e.g., the third electrode308) of a third width (e.g., the third width318) substantially the same as the second width and a fourth electrode (e.g., the fourth electrode310) of a fourth width (e.g., the fourth width320) substantially the same as the first width are fabricated on the second surface of the piezoelectric substrate. The first and third electrodes are arranged as a first portion of a microelectromechanical systems (MEMS) resonator (e.g., the staggered electrode resonator300or the staggered electrode resonator430). The second and fourth electrodes are arranged as a second portion of the MEMS resonator. In one configuration, the first portion and the second portion of the MEMS resonator may be aligned in that the first aligned portion contains the first and third electrodes aligned together. Similarly, the second aligned portion contains the second and fourth electrodes aligned together.

The process500may also include depositing another piezoelectric material layer (e.g., a second piezoelectric material layer, if the piezoelectric material layer deposited on the first surface of the piezoelectric substrate is referred to as the first piezoelectric material layer) on the second surface of the piezoelectric substrate. The process500may additionally include patterning that other piezoelectric material layer (or the second piezoelectric material layer) after it has been deposited on the second surface of the piezoelectric substrate. In one configuration, any of the piezoelectric material layers are deposited over any of the electrodes (e.g., the first through fourth electrodes) when they are deposited on any surface of the piezoelectric substrate that already contains electrodes.

In the process500, fabricating the first electrode of the first width and the second electrode of the second width may be performed as follows. Initially, a conductive layer is deposited on the first surface of the piezoelectric substrate. The depositing conductive layer is then patterned to form the first electrode and the second electrode from the deposited conductive layer. The conductive layer may be made of materials including Molybdenum (Mo), Platinum (Pt), Copper (Cu), Aluminum (Al), Silver (Ag), Gold (Au), Tungsten (W), Nickel (Ni), or other like materials. The conductive layer may be deposited onto the piezoelectric substrate by electroplating, chemical vapor deposition (CVD), and/or physical vapor deposition (PVD), such as sputtering or evaporation.

In an aspect of the present disclosure, patterning of the deposited conductive layer to form the first electrode and the second electrode may be performed as follows. A photoresist layer is initially depositing on the deposited conductive layer. The deposited photoresist layer is then exposed with light through a photolithography mask. The exposed portions of the photoresist layer are then etching away to form a photoresist pattern. Subsequently, the photoresist pattern is used guide etching of the deposited conductive layer to form the first electrode and the second electrode.

The light may be an ultraviolet light or deep ultraviolet light. The photoresist layer may be deposited by spin-coating, droplet-based photoresist deposition, and/or spraying. The exposed portions of the photoresist layer may be etched away using a chemical etching processes. This process may use solutions such as a photoresist developer, which may be made of, for example, tetramethylammonium hydroxide (TMAH), iron chloride (FeCl3), cupric chloride (CuCl2) or alkaline ammonia (NH3). Dry etching processes using plasmas may also be used to etch the first photoresist layer. The conductive layer is then patterned by any wet chemical or dry etching process, with the etched photoresist regions of the first photoresist layer (e.g., the photoresist pattern) being used to guide the etch process. The remaining portions of the first photoresist layer may then be stripped by a chemical photoresist stripping process using a photoresist stripper such as, for example, positive resist stripper (PRS-2000), n-methyl-2-pyrrolidone (NMP), or acetone. The photoresist layers may also be stripped by a dry photoresist stripping process using plasmas such as oxygen, which is known as ashing.

Also, the process500may include depositing a conductive layer on the second surface of the piezoelectric substrate to enable fabrication of the third electrode of the third width and the fourth electrode of the fourth width. The deposited, conductive layer may be patterned to form the third electrode and the fourth electrode.

In an aspect of the present disclosure, patterning of the third electrode and the fourth electrode from the deposited conductive layer may be performed as follows. A photoresist layer may be initially depositing on the deposited conductive layer. The photoresist layer is then exposed with light using a photolithography mask. The exposed portions of the photoresist layer is then etching away to form a photoresist pattern. Subsequently, the photoresist pattern is used as a guide to etch the deposited conductive layer to form the third electrode and the fourth electrode. Example substances and processes used to fabricate the third electrode and the fourth electrode are similar to the substances and processed used to fabricate the first electrode and the second electrode, as discussed above.

In one aspect, an integrated circuit device includes a means for supporting having a first surface and a second surface opposite the first surface. The device also includes a first electrode and a second electrode on the first surface of the supporting means. In this configuration, the first electrode has a first width and the second electrode having a second width different from the first width. The device further includes a third electrode and a fourth electrode on the second surface of the supporting means. The third electrode has a third width that is substantially the same as the second width. In addition, the fourth electrode has a fourth width that is substantially the same as the first width. The first electrode and third electrode may be arranged to operate a first portion of a microelectromechanical systems (MEMS) resonator. In addition, the second electrode and the fourth electrode may be arranged to operate as a second portion of the MEMS resonator. In one configuration, the supporting means may be the substrate302, which may be composed of a piezoelectric material, a ceramic material or other like material to provide support for the electrodes and other components of a staggered electrode resonator.

Both stress control methods and structures to achieve stress control are disclosed. Also, both spurious mode suppression methods and structures to achieve spurious mode suppression are disclosed. Any relevant piezoelectric materials may be used in the substrate and other components discussed above. Also, all different types of conductive material (e.g., metals) may be used for the electrodes, as the thermal coefficients of expansion of metals are usually higher than those of piezoelectric, ceramic or other like substrate materials. In one configuration, the first electrode and the second electrode may be fabricated at a first conductive layer (e.g., metal 1 (M1)). In this configuration, the third electrode and the fourth electrode may be fabricated at a second conductive layer (e.g., metal 2 (M2)).

FIG. 6is a block diagram showing an exemplary wireless communication system600in which an aspect of the disclosure may be advantageously employed. For purposes of illustration,FIG. 6shows three remote units620,630, and650and two base stations640. It will be recognized that wireless communication systems may have many more remote units and base stations. Remote units620,630, and650include IC devices625A,625C, and625B that include the disclosed staggered electrode resonators. It will be recognized that other devices may also include the disclosed staggered electrode resonators, such as the base stations, switching devices, and network equipment.FIG. 6shows forward link signals680from the base station640to the remote units620,630, and650and reverse link signals690from the remote units620,630, and650to base stations640.

InFIG. 6, remote unit620is shown as a mobile telephone, remote unit630is shown as a portable computer, and remote unit650is shown as a fixed location remote unit in a wireless local loop system. For example, the remote units may be mobile phones, hand-held personal communication systems (PCS) units, portable data units such as personal data assistants, GPS enabled devices, navigation devices, set top boxes, music players, video players, entertainment units, fixed location data units such as meter reading equipment, or other devices that store or retrieve data or computer instructions, or combinations thereof. AlthoughFIG. 6illustrates remote units according to the aspects of the disclosure, the disclosure is not limited to these exemplary illustrated units. Aspects of the disclosure may be suitably employed in many devices, which include the disclosed staggered electrode resonators.

FIG. 7is a block diagram illustrating a design workstation used for circuit, layout, and logic design of a semiconductor component, such as the staggered electrode resonators disclosed above. A design workstation700includes a hard disk701containing operating system software, support files, and design software such as Cadence or OrCAD. The design workstation700also includes a display702to facilitate design of a circuit710or a semiconductor component712such as a staggered electrode resonator. A storage medium704is provided for tangibly storing the design of circuit710or the semiconductor component712. The design of the circuit710or the semiconductor component712may be stored on the storage medium704in a file format such as GDSII or GERBER. The storage medium704may be a CD-ROM, DVD, hard disk, flash memory, or other appropriate device. Furthermore, the design workstation700includes a drive apparatus703for accepting input from or writing output to the storage medium704.

Data recorded on the storage medium704may specify logic circuit configurations, pattern data for photolithography masks, or mask pattern data for serial write tools such as electron beam lithography. The data may further include logic verification data such as timing diagrams or net circuits associated with logic simulations. Providing data on the storage medium704facilitates the design of the circuit710or the semiconductor component712by decreasing the number of processes for designing semiconductor wafers.