Patent Application
20110198202
The present invention relates to micro-electro-mechanical system (MEMS) and methods for forming the same, and more specifically to ultra-low power MEMS devices.
In general, telecommunications devices include a combination of electronic elements, including switches, capacitors, and inductors. Although some telecommunications devices can be configured to utilize a combination of discrete elements, other telecommunications devices can be configured to include these electronic elements in one or more integrated circuits. For example, these electronic elements can be provided via a combination of metal oxide semiconductor (MOS) transistors, diodes, and capacitors, PIN diodes, and/or bipolar junction transistors (BJTs). However, as the functionality of telecommunications devices has increased, the number of electronic elements needed in an integrated circuit has increased exponentially. As a result, each generation of integrated circuits generally requires an amount of power significantly higher than its predecessor.
Embodiments of the invention provide methods for fabricating ultra-low power micro-electro-mechanical system (MEMS) devices and devices therefrom. In a first embodiment of the invention, a gap closing actuator (GCA) device is provided. The GCA device includes at least one device drive comb structure, at least one input/output comb (I/O) structure defining an output of the GCA device, and at least one device truss comb structure interdigitating the device drive comb structure and the I/O comb structure. The device truss comb structure is configured to move along a first motion axis between a plurality of interdigitated positions based on a first bias voltage applied between the truss comb structure and the device drive comb structure. The GCA device also includes a brake portion configured for selectively physically engaging the device truss comb structure to fix a position of the device truss comb structure along the first motion axis.
In a second embodiment of the invention, a method of manufacturing micro-electro-mechanical (MEMS) device is provided. The method includes providing a substrate having a stack of layers including at least one base layer, at least one release layer on the base layer, and at least one structure layer on the release layer. The method also includes depositing at least one electrically conductive layer on the structure layer. The method further includes forming a plurality of voids in the electrically conductive layer, the structure layer, and the release layer to define a plurality of patterned regions. The patterned regions define at least one device drive comb structure, at least one input/output (I/O) comb structure, at least one device truss comb structure interdigitating the device drive comb structure and the I/O comb structure, and a brake portion. In the method, the forming step further includes selecting the plurality of voids to further configure said device truss comb structure for selectively moving along a first motion axis between a plurality of interdigitated positions and to further configure the brake portion for selectively moving to physically engage the device truss comb structure.
In a third embodiment of the invention, a system is provided. The system includes a plurality of GCA devices. Each of the plurality of GCA devices includes at least one device drive comb structure, at least one I/O comb structure defining an output, and at least one device truss comb structure interdigitating the device drive comb structure and the I/O comb structure, where the device truss comb structure configured to move along a first motion axis between a plurality of interdigitated positions based on a first bias voltage applied between the device truss comb structure and the device drive comb structure. Each of the GCA devices also includes a brake portion configured for selectively physically engaging the device truss comb structure to fix a position of the device truss comb structure along the first motion axis. The system further includes a control element configured for providing the first and the second bias voltages to the GCA device.
The present invention is described with reference to the attached figures, wherein like reference numerals are used throughout the figures to designate similar or equivalent elements. The figures are not drawn to scale and they are provided merely to illustrate the instant invention. Several aspects of the invention are described below with reference to example applications for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One having ordinary skill in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details or with other methods. In other instances, well-known structures or operations are not shown in detail to avoid obscuring the invention. The present invention is not limited by the illustrated ordering of acts or events, as some acts may occur in different orders and/or concurrently with other acts or events. Furthermore, not all illustrated acts or events are required to implement a methodology in accordance with the present invention.
As described above, one of the problems with conventional integrated circuit (IC) development is the increasing amount of power needed for each generation of ICs. In general, this problem arises because MOS, PIN diode, and BJT devices typically operate in response to an active signal. That is, unless a signal is actively provided to the device, it will not generally function. For example, in the case of complementary MOS devices, when a MOS transistor is used as a switch, closing of the switch (i.e., allow a current to flow) typically requires that a voltage be applied to the gate electrode of the MOS transistor. Further, to maintain the switch in the closed position, the voltage needs to be maintained. As a result, a significant amount of power is used to maintain the MOS transistor in a closed state. PIN diode and BJT devices operate in a similar fashion. An additional problem with the use of MOS, PIN diode, and BJT devices is that these devices generally provided limited performance in telecommunications applications. In general, solid state devices generally provide a path for signals, even when not active. As a result, poor isolation of signals is common for such devices resulting in increased noise and interference. Therefore, in order to reduce power requirements and address signal isolation issues in IC-comprising telecommunications, it has been proposed that telecommunications devices be fabricated using micro-electro-mechanical system (MEMS) technologies. In MEMS devices, the operation of the device is generally based on mechanical motion and therefore improved isolation can be achieved by designing the MEMS switch to physically separate components in the IC.
However, telecommunications ICs including conventional MEMS switch and capacitor devices are typically difficult to fabricate. In particular, conventional MEMS-based switches and conventional MEMS-based capacitors generally have significantly different geometries, requiring more complex processes and designs to successfully form both types of devices on the same substrate. This typically results in manufacturing techniques with smaller process margins, increasing overall development and manufacturing costs. Further, even though such MEMS-based switches and capacitors generally consume the less power than MOS, PIN diode, and BJT devices, the difference in power consumption is typically insignificant. In particular, MEMS-based devices, like their MOS, PIN-diode, or BJT device counterparts, generally require an active signal to operate. Accordingly, even though improved isolation is provided, power consumption is generally not significantly reduced.
In order to overcome the various limitations of conventional MEMS devices, embodiments of the invention provide systems and methods for providing ICs with ultra-low power MEMS devices. In the various embodiments of the invention, these MEMS devices are designed to have common geometries to reduce overall complexity and costs of fabricating ICs including such MEMS devices. In particular, the various embodiments of the invention utilize MEMS horizontal gap closing actuator (GCA) devices with common geometries to form switches devices, adjustable capacitors, and other devices. Further, to provide ultra-low power operation of such MEMS devices, a brake portion is provided in the devices for mechanically fixing a position of the moving portions of these MEMS devices without the need for maintaining an active signal. Thus, MEMS devices in accordance with an embodiment of the invention use significantly less power than conventional MEMS, MOS, PIN diode, and BJT devices.
As used herein with respect to MEMS devices, the term “horizontal GCA device” refers to a GCA MEMS device in which actuation and interaction of the components in the MEMS device is limited to directions parallel to the supporting substrate. That is, actuation of the horizontal GCA device results in a substantially lateral motion. Consequently, the horizontal MEMS devices can be fabricated with one or two masks rather than the multiple masks (>2) typically required for conventional IC or MEMS devices. This reduces the overall complexity for designing and manufacturing MEMS-based devices, such as telecommunications ICs. Furthermore, horizontal MEMS GCA devices in accordance with the various embodiments of the invention can be easily modified to provide various types of devices, such as switches and adjustable capacitors (i.e., varactors), without significantly affecting operation or manufacture of such devices. The basic operation and manufacture of horizontal GCA devices in accordance with the various embodiments of the invention is described below with respect to
As shown in
In the embodiment shown in
The drive portion 100 shown in
As shown in
The drive portion illustrated in
The drive portion described above could be coupled to any variety of devices. Still such a drive portion for various types of devices will only provide a partial improvement in manufacturing robustness and device reliability. In general, the robustness of the IC fabrication techniques used for fabricating MEMS and other types of devices is increased by reducing the variety of feature types and dimensional variation in each layer. The various embodiments of the invention exploit this characteristic. In particular, another aspect of the invention is to use the comb structure drive portion in conjunction with a comb structure based reactive portion to provide device functionality for a filter. Therefore, in the various embodiments of the invention, one structure that can be used to provide a variety of devices is shown below in
Device truss comb structure 204 also includes elastic portions 210 with fixed ends 212a and 212b (collectively 212). In the exemplary embodiment shown in
In addition to the drive portion 201, MEMS horizontal GCA devices in accordance with the various embodiments of the invention also provide a reactive portion 214, as shown in
In addition to the drive portion 201 and the reactive portion 214, MEMS horizontal GCA devices in accordance with the various embodiments of the invention also include at least one brake portion 230 for fixing a lateral position of device truss comb structure 204. As shown in
In the various embodiments of the invention, motion of brake truss comb structure 234 along motion axis 246 will result in the spacing between fingers 236 and 238 to change. Thus, adjustment of the spacing between fingers 236 and 238 using a brake bias voltage (VBRAKE) can be used to move the brake comb structure from a brake position to a release position.
The brake portion 230 and device truss comb structure 204 are configured to mechanically engage via a series of engagement features. For example as shown in
As shown in
In operation, device 200 operates to adjust a position of device truss comb structure 204 along motion axis 205 as described below. In some embodiments, a force can be first exerted on brake truss comb structure 234 (by generating a voltage difference VBRAKE between fingers 236 and 238 to cause the reed structures 244 deform and allow brake truss comb structure 234 to move along the brake motion axis 244 from a brake position to release position. That is, the brake truss comb structure 234 is moved towards brake fixed end 242 to separate the brake engagement features 248 and the truss engaging features 228. Second, a force is exerted on device truss comb structure 204 (by generating a voltage difference VBIAS between fingers 206 and 208 to cause the reed structures 211 to deform) to allow device truss comb structure 204 to move in a first direction along motion axis 205 (towards fixed end 212b) to a different interdigitated position. Alternatively, a force on device truss comb structure 204 can be reduced (by generating a lower or zero voltage difference between fingers 206 and 208 to cause the reed structures 211 to undeform) to allow device truss comb structure 204 to move in an opposite direction along motion axis 205 (towards fixed end 212a) to a different interdigitated position.
Once a desired interdigitated position for device truss comb structure 204 is achieved, the force on brake truss comb structure 234 is removed, i.e., by removing the voltage difference VBRAKE between fingers 236 and 238. Once the force is no longer being exerted on brake truss comb structure 234, the brake reed structures 244 apply a restorative force to restore the position of the brake device truss comb structure 234 to the brake position. In the brake position, the brake engagement features 248 and the truss engaging features 228 mechanically engage and retain device truss comb structure 204 in a position along motion axis 205. Afterwards, the force on device truss comb structure 204 can also be removed, i.e., by removing the voltage difference between fingers 206 and 208. However, since the brake engagement features 248 and the truss engaging features 228 are physically engaging and provide a frictional force greater than a restorative force of reed structure 211, the position of device truss comb structure 204 remains fixed at the position associated with the VBIAS originally applied.
In other embodiments, the truss engagement features 228 and the brake engagement features 248 can be designed to allow in one or both directions along motion axis 205 without the need to apply a force to the brake truss comb structure 234. For example, as shown in
The operation and configuration of components 202-212 and 233-244 is substantially similar to that of components 102-112 in
In the embodiment shown in
Additionally, as described above with respect to
As described above, motion of device truss comb structure 204 along motion axis 205 is generated by developing a voltage difference in drive portion 201. In particular, by developing a voltage difference between across fingers 206 and 208 by apply a voltage across device drive comb structures 202 and device truss comb structure 204. The voltage difference causes the finger spacing (x0
The structure shown in
Manufacture of device 200 begins with the formation of the various layers used to form the structures in
In the various embodiments of the invention, the composition of structural layer 306 is selected such that it is electrically non-conductive. Furthermore, the composition of release layer 304 is selected such that it can be selectively removable, with respect to base layer 302, structural layer 306, and conductive layers 308, 309, using at least one removal process. For example, in some embodiments of the invention, layers 302-306 are provided by using a silicon on insulator (SOI) substrate. In such a substrate, the silicon oxide comprising layer sandwiched between two layers of silicon provides release layer 304 between the silicon-comprising base layer 302 and structural layer 306. One of ordinary skill in the art will recognize that various types of etch processes are readily available for removing silicon oxide comprising materials without substantially removing silicon comprising materials. However, the invention is not limited to SOI substrates. In other embodiments of the invention, the release layer 304 and structural layer 306 are formed on a silicon substrate that provides base layer 302. In still other embodiments, non-silicon comprising materials are used for forming layers 302-306.
Once layers 302-309 are formed, formation of the structures for device 200 can begin. In general, the structures shown in
Although the exemplary mask pattern shown in
Once the masking pattern has been transferred into structural layer 306, portions of release layer 304 are removed to “release” at least some portions of device truss comb structure 204. This can be accomplished by providing an isotropic selective removal process to device 200. An isotropic process not only removes the exposed portions of release layer 304, but will also removes portions of release layer 304 (i.e., creates voids) beneath structural layer 306 in the vicinity of openings in structural layer 306 (i.e., undercut these structures). If the lateral dimensions of features in structural layer 304 are small enough (such as under reed structures 211, fingers 206, and fingers 208 shown in
The various embodiments of the invention are not limited to the exemplary manufacturing process described above. For example, in some embodiments of the invention, atomic layer epitaxial (ALE) processes are used to form conductive layers 308, 309 after etching of structural layer 306 and removal of release layer 304. In such embodiments, use of ALE process allows precise control of placement and thickness of conductive layer. As a result, device control can be improved since the dimensions of the active portions of the horizontal GCA device can be constructed with higher precision.
As described above, device 200 can be easily modified to provide various types of devices. In particular, by varying X0
As described above, device 400 is configured for operating as a switch without significant changes in design, manufacture, and operation principles as compared to device 200 and other horizontal GCA devices in accordance with the various embodiments of the invention. That is, the device truss comb structure 404 is configured to electrically couple a first input/output comb structure 416a to a second input/output comb structure 416b. This can be accomplished by providing a configuration of the finger spacing between fingers 418 and 420 such that when the finger spacing between fingers 406 and 408 is reduced, fingers 418 and 420 come into contact to close the switch and to allow current to flow between input comb 416a and output comb 416b. In other words, a switch is provided when X0
In addition to dimensioning the device drive comb structure 402 and the input/output comb structures 416 to allow contact of fingers 418 and 420, additional modifications of device 200 in
The MEMS structures described above comprise electrically conductive layers supported by electrically non-conductive layers. Therefore, for device 400 to operate properly as a switch, some discontinuities in the conductive layer may be required for several reasons. First, if a voltage difference develops between fingers 418 and 420, the device truss comb structure 404 will also be subject to motion due to the electrostatic force generated between fingers 418 and 420. Second, when fingers 418 and 420 are brought into contact, the signal at input/output comb 416a needs to reach input/output comb 416b without being shorted to ground or some other reference point, such as fixed end 412a. Finally, when fingers 418 and 420 are brought into contact, the signal at input/output combs 416 should not interfere with the operation of drive portion 401. Similarly, the operation of brake portions 430 and truss engagement features 428 should also not interfere with the operation of drive portion 401 or the output of device 400. In particular, the voltage difference between fingers 406 and 408 should be only controlled by a voltage difference applied directed to fingers 406 and 408 and not be affected by the voltage at the input/output combs 416 or voltages in the brake portion 430.
Therefore, to avoid such issues in device 400, the electrically conductive layer on or in device truss comb structure 404 can be configured to have discontinuities, such as discontinuities 422, 424, and 426. The discontinuities 422-426 electrically isolate fixed end 412a, truss engagement features 428, fingers 420, and fingers 408 in device truss comb structure 404. Accordingly, any voltages in one portion of device 400 will not affect the operation of another portion of device 400.
In one embodiment of the invention, switch device 400 can operate as follows. An input signal, such as VSOURCE, is applied between input comb 416a and fixed end 412a. To close the switch, a voltage difference VBRAKE is first developed between fingers 436 and 438 to move the brake truss comb structure 434 to a release position to allow motion of device truss comb structure 404. Afterwards, a voltage difference is developed between fingers 406 and 408. For example, a voltage VBIAS is applied between device drive comb structures 402 (which are electrically coupled to fingers 406) and fixed end 412b (which is electrically coupled to fingers 408). The amount of VBIAS is selected to cause motion of device truss comb structure 404 along motion axis 405 that is sufficient to move fingers 420 into contact with fingers 418, thus closing the switch. For example, VBIAS is selected to create an electrostatic force greater than the restorative force of reed structures 411. Once the desired motion of device truss comb structure 404 is achieved, VBRAKE can be reduced to move the brake truss comb structure 434 to a brake position to fix the position of device truss comb structure 404. Thereafter, VBIAS can be reduced. However, the brake portion 430 acting on the device truss comb structure 404 maintains the switch in a closed position without consuming additional power.
To open the switch, a voltage difference VBRAKE is first developed between fingers 436 and 438 to move the brake truss comb structure 434 to a release position to allow motion of device truss comb structure 404. Further, no VBIAS is applied between device drive comb structures 402 (which are electrically coupled to fingers 406) and fixed end 412b (which is electrically coupled to fingers 408). As a result, the restorative force of elastic portions 410 restores a position of device truss comb structure 404, separating fingers 418 and 420, opening switch. Thereafter, VBRAKE can be reduced to move the brake truss comb structure 434 to a brake position to fix the position of device truss comb structure 404. The brake portion 430 acting on the device truss comb structure 404 thus maintains the switch in an open position until an additional VBRAKE and VBIAS are applied to device 400.
In other embodiments, the truss engagement features 428 and the brake engagement features 448 can be designed to allow switch device 400 to be closed without the need to apply a force to the brake truss comb structure 434, as described above with respect to
In some embodiments of the invention, the position and arrangement of the truss engagement features 428, the brake engagement features 448, and fingers 418 and 420 can be designed such that the engagement features 428 and 448 position fingers 418 and 420 in electrical contact. However, due to manufacturing variations, the arrangement in
As described above, the device 200 can also be configured to provide functionality as another type of device, such as an adjustable capacitor or varactor, also without significant changes in design, manufacture, and operation principles. This is illustrated below with respect to
As described above, device 500 is configured for operating as a varactor. In particular, the device truss comb structure 504 is configured to provide an adjustable capacitor based on adjustment of the gap between a first capacitor plate, provided by fingers 518, and a second capacitor plate, provided by fingers 520. Therefore, device 500 forms a first capacitor between comb structure 516a and device truss comb structure 504, with a capacitance of COUT1, and a second capacitor between comb structure 516b and device truss comb structure 504, with a capacitance of COUT2.
As described above, device 500 is configured for operating as a varactor without significant changes in design, manufacture, and operation principles. That is, the device truss comb structure 504 is configured to adjust the finger spacing between fingers 518 and 520 as the finger spacing between fingers 506 and 508 is reduced. However, to maintain proper operation of the varactor, the fingers 518 and 520 should not come into contact to allow current to flow between comb structure 516a and comb structure 516b. Therefore, in the various embodiments of the invention, x0
In the various embodiments of the invention, these first and second capacitors can be connected in various ways to provide capacitances in series or parallel. For example, to provide a series capacitance, the capacitance can be measured between comb structures 516a and 516b. In contrast to provide a parallel capacitance, the capacitance can be measure between comb structures 516a, 516b and fixed end 512a (if electrically coupled to fingers 520).
As described above, the MEMS structures described above comprise electrically conductive layers supported by electrically non-conductive layers. Therefore, for device 500 to operate properly as a varactor, some discontinuities in the conductive layer may be required for several reasons. In particular, if a voltage difference develops between fingers 518 and 520, the device truss comb structure 504 will also be subject to motion due to the electrostatic force generated between fingers 518 and 520. Additionally, if fingers 506 and 508 are brought into contact, the signal in device drive comb structure 502 should not interfere with the operation of reactive portion 514. Similarly, the operation of brake portions 530 and truss engagement features 528 should also not interfere with the operation of drive portion 501 or the output of device 500. In particular, the voltage difference between fingers 506 and 508 should be only controlled by a voltage difference applied directed to fingers 506 and 508 and not be affected by the voltage at the input/output combs 516 or voltages in the brake portion 530.
Therefore, to avoid such issues in device 500, the electrically conductive layer on or in device truss comb structure 504 can be configured to have discontinuities, such as discontinuities 522, 524, and 526. The discontinuities 522-526 electrically isolate fixed end 512a, truss engagement features 528, fingers 520, and fingers 508 in device truss comb structure 504. Accordingly, any voltages in one portion of device 500 will not affect the operation of another portion of device 500.
Device 500 operates in one embodiment of the invention as follows. A circuit (not shown) is coupled to comb structures 516a, 516b, and fixed end 512a (if necessary, as described above). To provide an amount of capacitance, a voltage difference VBRAKE is first developed between fingers 536 and 538 to move the brake truss comb structure 534 to a release position to allow motion of device truss comb structure 504. Thereafter, a voltage difference VBIAS is developed between fingers 506 and 508 to generate electrostatic attraction between these fingers. For example, VBIAS is applied across device drive comb structures 502 and fixed end 512b (which is electrically coupled to fingers 508) to cause sufficient electrostatic attraction between fingers 506 and 508 to induce motion of device truss comb structure 504, and consequently motion of fingers 520 towards fingers 518. The magnitude of VBIAS is selected to provide a gap associated with a spacing between fingers 518 and 520, and consequently capacitance value. For example, to increase capacitance, VBIAS is selected to create an electrostatic force that is at least greater than the restorative force of reed structures 511 to cause motion of device truss comb structure 504 along motion axis 505 and reduce a spacing between fingers 518 and 520. Once the desired motion of device truss comb structure 504 is achieved, VBRAKE can be reduced to move the brake truss comb structure 534 to a brake position to fix the position of device truss comb structure 504. Thereafter, VBIAS can be reduced. However, the brake portion 530 acting on the device truss comb structure 504 maintains the spacing between fingers 518 and 520, and thus a capacitance, without consuming additional power.
Afterwards, to change the capacitance, a voltage difference VBRAKE is first developed between fingers 536 and 538 to move the brake truss comb structure 534 to a release position to allow motion of device truss comb structure 504. A different VBIAS is then provided. If the new VBIAS is less than the previous VBIAS, the resulting electrostatic force will be less. Thus, the restoring force applied by reed structures 511 acts on device truss comb structure 504 to increase the gap between fingers 520 from fingers 518, and thus decrease the capacitance. If the new VBIAS is greater than the previous VBIAS, the resulting electrostatic force will be greater. Thus, the greater electrostatic force acts on device truss comb structure 504 to further decrease the gap between fingers 520 from fingers 518, and thus increase the capacitance. Once the desired motion of device truss comb structure 504 is achieved, VBRAKE can be reduced to move the brake truss comb structure 534 to a brake position to fix the position of device truss comb structure 504. Thereafter, VBIAS can be reduced. However, the brake portion 530 acting on the device truss comb structure 504 maintains the new spacing between fingers 518 and 520, and thus a capacitance, without consuming additional power.
In other embodiments, the truss engagement features 528 and the brake engagement features 548 can be designed to allow varactor device 500 to be adjusted without the need to apply a force to the brake truss comb structure 534, as described above with respect to
As described above, operation of a MEMS comb device in accordance with the various embodiments of the invention typically requires some coordination between the application of VBRAKE and VBIAS. In some embodiments of the invention, VBRAKE and VBIAS can be applied in the fashion described above by manually applying the voltages at the times needed. However, in other embodiments of the invention, VBRAKE and VBIAS can be applied automatically. This is illustrated below with respect to
In the various embodiments of the invention, the number and configuration of devices 400 and 500 can vary depending on the type of system. For example, a system 600 can be provided in which one of devices 400 and 500 is not present. In another example, system 600 can be configured to combine devices 400 and 500 to provide other types of devices, such as filters. However, the various embodiments of the invention are not limited in this regard and any configuration of devices 400 and/or 500 can be used.
As described above, timing of VBRAKE and VBIAS signals is generally needed to operate the devices 400 and/or 500 properly. As a result, when a large number of such devices are present, it can be difficult to manually operate each of these devices accurately to provide proper operation of system 600. Accordingly, in some embodiments of the invention, a controller 602 can be provided to coordinate the timing of VBRAKE and VBIAS signals and to coordinate the overall operation of devices in system 600.
Controller 602 can be implemented in a variety of ways. For example, controller 602 can be implemented as logic circuitry formed on a same substrate as one or devices 400 and 500. In another example, controller 602 can be implemented as one or more separate hardware devices including, but not limited to, application-specific integrated circuits, programmable logic arrays, and other hardware devices. Some embodiments implement functions in two or more specific interconnected hardware modules or devices with related control and data signals communicated between and through the modules, or as portions of an application-specific integrated circuit. Thus, controller 600 can be implemented using software, firmware, and/or hardware in the various embodiments of the invention.
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit or scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above described embodiments. Rather, the scope of the invention should be defined in accordance with the following claims and their equivalents.
Although the invention has been illustrated and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the ” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description and/or the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.”
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
