Patent Publication Number: US-8536964-B2

Title: Micro-electro-mechanical switch beam construction with minimized beam distortion and method for constructing

Description:
RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 12/755,285, filed on Apr. 6, 2010, which is a continuation-in-part of U.S. patent application Ser. No. 12/338,767, filed on Dec. 18, 2008, now U.S. Pat. No. 8,294,539. The disclosure of these previous applications is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The present invention is directed to a micro-electro-mechanical switching (MEMS) device having a beam that is actuated in a manner similar to an electrical relay, and specifically, to such a MEMS device beam having structures, and constructed in a manner, to minimize the distortion of the beam when subject to thermal expansion. 
     Due to the small size of a MEMS device and the materials from which it is made, the parts of the device are subject to closer tolerances and experience the effects of the environment much more greatly than larger devices. The MEMS device is made, preferably, from gold because of its electrical conducting properties and silicon for suitability for integrated circuit fabrication. The gold and silicon have different properties and are affected by the environment in different ways. In particular, when a MEMS device is manufactured and operated, it is subject to a variety of environmental conditions, such as excessive heat. When subject to excessive heat, the gold and silicon from which a MEMS device are made expand at different rates, which can cause distortion in the structure of the MEMS device. This material expansion and resulting distortion can be compensated for during the design process but only to a certain degree. 
     For example, the linear expansion of a material AL due to temperature can be determined from
 
ΔL=α.L0.ΔT
 
where α is the coefficient of thermal expansion, L 0  is the length at the initial temperature, and ΔT is the change in temperature.
 
     A configuration of a conventional MEMS switch is shown in  FIG. 1  in a cross-sectional view. The MEMS switch  100  comprises a substrate  110  and a switch  120 . The substrate  110  is formed from a semiconductor material such as silicon and coated with a dielectric material such as silicon dioxide or the like. The substrate  110  can also be a dielectric material such as sapphire or the like. The switch  120  includes an anchor  121 , a hinge  123 , a beam  125 , and a tip  127 . The anchor  121  couples the switch  120  to the substrate  110 . The switch  120  also forms a current path or trace comprising the anchor  121 , the hinge  123 , the beam member  125 , and the tip  127 . The switch  120  is formed from gold, or some other suitable conductor. The current path via the anchor  121  is electrically connected to a source connection  113 . The switch  120  is actuated by a voltage applied to a gate connection  115 . The hinge  123  flexes in response to the voltage differential established between the gate connection  115  and the beam member  125  by the applied voltage. In response to the flexing, the tip  127  contacts the drain connection  117 , completing a current path from a source connection  113  to the drain  117 . Of course, the source connection  113  and the drain connection  117  can be interchanged without substantially affecting the operation of the MEMS switch  110 . As the electric field at the gate connection  115  dissipates, the beam  125  raises thereby lifting the tip  127  from the drain connection  117 . 
     During manufacturing, the MEMS device  100  can be subjected to high heat, such as approximately 400° C., which may cause distortion of the components of the MEMS device  100 . Also, in operation, the MEMS device  100  will begin to experience heat, or thermal effects, associated with the application of voltage at gate connection  115  and electrical current through the current path from source connection  113  to drain connection  117 , as well as heat from other sources on the substrate  110  or nearby, or even from the environment. In some cases of distortion, the beam  125  will lower toward the gate  115  due to thermal expansion and the tip  127  will contact drain connection  117 . Although described with respect to a single switch, it is understood that the MEMS device  100  can comprise more than one switch  120  on a substrate  100 , and the above description should not be interpreted to be limited to a single switch. In cases of multiple MEMS devices configured adjacent to one another, the beam  125  will distort such that the deflection of the tip  127  is different from that of neighboring tips. Such non-uniform deflection can be due to non-symmetric mechanical constraints, non-uniform fabrication process variations, other non-optimal operating conditions, other reasons, and/or combinations thereof. The non-uniform deflection may result, for example, in all tips  127  not making uniform contact, which can cause variations in the voltage required to actuate a particular switch in comparison to the voltage required to actuate other switches. 
     At the gold-substrate interface at an anchor point in a MEMS device, there is a difference in thermal expansions. Gold expands at almost 5 times the rate of silicon, and nearly 10 times the rate of silicon dioxide (SiO2). So there is a thermal expansion differential at differing points, such as the anchor point, of the MEMS device, with gold expanding the most. For example, at the gold-substrate interface, gold expands by approximately 0.56% when a temperature of 400° C. differential is applied, while silicon expands by approximately 0.12%. The difference in thermal expansion causes a shear force between them which can contribute further to distortion in the MEMS device and possibly device failure. 
     Because the substrate will not bend in the normal bimetallic fashion due to its much larger mass (i.e., the whole wafer), it is expected the gold at the interface would expand approximately 0.12%, although under stress, whereas the gold at the top of the MEMS device would expand at approximately 0.56%. This thermal expansion mismatch between the top and the bottom of anchor  121  is problematic because the distortion of anchor  121  may cause displacements in the beam  120  and the tip  127 . If the thermal displacement at the tip  127  equals the separation distance between the tip  127  and the drain  117 , the source  113  and the drain  117  will become electrically short-circuited. Further distortion at the anchor  121  will induce mechanical stresses in the beam  120  and the tip  127 . Again, distortion caused by thermal expansion can cause performance problems in the MEMS device  100 . 
     Another problem resulting from unmitigated thermal expansion is a tendency, in cases of multiple MEMS devices is for the beams  120  of MEMS devices to spread apart, in a shape similar to a hand-held fan, from one another in the horizontal plane. The spreading apart can cause misalignment of the components of the MEMS devices. Because of non-symmetric mechanical boundary conditions among the beams  120 , such spreading apart will cause non-uniform tip displacements. 
     Accordingly, there is a need in the art to address the thermal expansion and distortion of the structures in the MEMS device, and thereby reduce complexity of associated circuitry that attempts to overcome the effects of the distortion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a cross sectional view of a conventional MEMS device. 
         FIGS. 2A and 2B  illustrate, respectively, a cross sectional view and a rear view of a MEMS device according to an exemplary embodiment of the present invention. 
         FIG. 3  illustrates a rear view of a MEMS device according to another exemplary embodiment of the present invention. 
         FIG. 4  illustrates a top view of a configuration of the beams of a MEMS device according to another exemplary embodiment of the present invention. 
         FIGS. 5A and 5B  illustrate a buttress configuration of the anchor from a cross sectional view and from a top view of a MEMS device according to an exemplary embodiment of the present invention. 
         FIG. 6  is a top-view of an exemplary configuration of the anchor of a MEMS device according to an embodiment of the present invention. 
         FIG. 7  illustrates a top-view of an exemplary configuration of a beam of a MEMS device according to an embodiment of the present invention. 
         FIG. 8  illustrates a three-dimensional plane view of an exemplary configuration of the beam and anchor of a MEMS device according to another embodiment of the present invention. 
         FIG. 9  illustrates a plan view of an exemplary configuration of an anchor airbridge tie shown according to an embodiment of the present invention. 
         FIG. 10  illustrates a sectional view of an exemplary configuration of the anchor airbridge tie shown in  FIG. 9  according to an embodiment of the present invention. 
         FIG. 11  illustrates a top-view of an exemplary configuration of a beam of a MEMS device according to yet another embodiment of the present invention. 
         FIG. 12  illustrates a method for producing a switch according to an exemplary embodiment of the present invention. 
         FIG. 13  illustrates a three-dimensional plane view of an exemplary configuration of the beam and anchor of a MEMS device according to yet another embodiment of the present invention. 
         FIG. 14  illustrates a three-dimensional plane view of an exemplary configuration of the beam and anchor of a MEMS device according to a further embodiment of the present invention. 
         FIG. 15  illustrates a sectional view of an exemplary configuration of the beam and anchor of a MEMS device shown in  FIG. 14  according to a further embodiment of the present invention. 
         FIG. 16  illustrates a top-view of an exemplary configuration of the MEMS device according to a further embodiment of the present invention. 
         FIG. 17  illustrates a sectional view of an exemplary configuration of the beam and anchor of a MEMS device according to another embodiment of the present invention. 
         FIG. 18  illustrates a cross-sectional view of an exemplary configuration of the beam and anchor of a MEMS device according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     To overcome the problems associated with distortion caused by thermal expansion of components of the MEMS device, the disclosed construction can mitigate the effects of thermal expansion of the device, and provide a MEMS device having minimized distortion while maintaining its operating characteristics. This is accomplished by providing voids in an anchor behind a hinge of a MEMS device and reducing the quantity of mass of the anchor, both of which minimize the effects of thermal expansion. 
     Embodiments of the present invention relate to a micro-electro-mechanical switch, and may include a switch structure coupled to a substrate. The substrate may have a gate connection, a source connection and a drain connection. The switch structure may include a beam member, an anchor, an anchor beam interface and a hinge. The beam member may have a length sufficient to overhang both the gate connection and the drain connection of the substrate. The anchor may have a first thickness, and may couple the switch structure to the substrate. The anchor may have an anchor slot that extends through the anchor to the substrate. The anchor beam interface may have a second thickness, and may be coupled to the anchor. The second thickness may be greater than the first thickness. The hinge may couple the beam member to the anchor beam interface, and may be configured to flex in response to a voltage differential established between the gate connection and the beam member. The hinge may be offset from the anchor beam interface in a vertical plane at an anchor beam interface end located between the anchor beam interface and the hinge. 
     Another embodiment of a micro-electro-mechanical switch may include a plurality of switch structures coupled to a substrate, which may have a plurality of gate connections and a plurality of drain connections. The plurality of switch structures may include a plurality of beam members, an anchor, a plurality of anchor slots, a plurality of anchor beam interfaces, and a plurality of hinges. The plurality of beam members may each have a length sufficient to overhang a respective gate connection and a respective drain connection of the plurality of gate connections and plurality of drain connections of the substrate. Each individual beam of the plurality of beams may be connected to an adjacent beam by a cross connection member that forms an open slotted region that separates the adjacent beams from one another. The anchor, which may have a first thickness, may be coupled to the substrate. The plurality of anchor beam interfaces may couple the anchor to the plurality of beams. The anchor beam interfaces may have a second thickness different from the first thickness of the anchor. The plurality of anchor slots may be located in the anchor proximate to a respective one of the plurality of anchor beam interfaces. The plurality of hinges may each be offset in the vertical plane from the anchor beam interface, and may be coupled to a respective one of the plurality of anchor beam interfaces and to a respective one of the plurality of beam members. Each of the hinges may be configured to flex in response to a voltage differential established between a respective one of the gate connections and the beam member. The plurality of hinges may have a thickness that is the same as the second thickness. 
       FIGS. 2A and 2B  illustrate a configuration of a MEMS device according to an exemplary embodiment of the present invention.  FIG. 2A  illustrates a cross-sectional view of the MEMS device. The cross section of  FIG. 2A  is taken at sectional  2 A shown in  FIG. 2B . The MEMS device  200  comprises a substrate  210  and a switch  220 . The switch  220  includes an anchor  221 , a hinge  223 , a beam  225 , and a tip  227 . The anchor  221  couples the switch  220  to the substrate  210 . The switch  220  also forms a current path or trace comprising the anchor  221 , the hinge  223 , the beam member  225 , and the tip  227 . The switch  220  is formed from gold, or some other suitable conductor. The current path via the anchor  221  is electrically connected to a source connection  213 . 
     The switch  220  is actuated by a voltage applied to a gate connection  215 . The hinge  223  flexes in response to the voltage, or charge, differential established between the gate connection  215  and the beam member  225  by the applied voltage. In response to the flexing, the tip  227  contacts the drain connection  217 , completing a current path from a source connection  213  to the drain  217 . Of course, the source connection  213  and the drain connection  217  can be interchanged without substantially affecting the operation of the MEMS switch  210 . As the electric field at the gate connection  215  is taken away, the beam  225  raises thereby lifting the tip  227  from the drain connection  217 . The anchor  221  of the switch is configured to include a gap  222  that extends laterally through the anchor  221 . The gap  222  can have the same dimensions from the rear of the anchor  221  to the front of the anchor  221 . Of course, the dimensions of the gap  222  in anchor  221  may vary from wider to narrower and vice versa in all directions, i.e., front to rear, rear to front, up to down or down to up. Specifically, the gap  222  may have various heights in the Z-axis that extend from a point substantially co-planar with source connection  213  to a point co-planar with the bottom of hinge  223  and/or beam  225 . In addition, the shape does not have to be rectangular, but may be circular, polygonal, cylindrical, triangular or any shape that provides suitable stress-relieving properties. 
     The gap  222  may be located beneath the hinge  223 , but does not necessarily have to be located precisely beneath the hinge  223 . The alignment of the gap  222  and the hinge  223  can be readily seen in  FIG. 2B .  FIG. 2B  is a rear view of a MEMS device  200  according to an exemplary embodiment of the present invention. As illustrated in  FIG. 2B , the gap  222  may be aligned to be substantially centered, although it is not required to be, in a vertical plane beneath the hinge  223 . Other gap  222  configurations are possible, such as conical or cylindrical. 
       FIG. 3  illustrates another rear view of a MEMS device according to another exemplary embodiment of the present invention. In this embodiment, gaps  322  may be provided between the substrate  310  and the switch  320  in an area behind a beam  325 . The gaps  322  need not be entirely void of interconnecting structures between the substrate  310  and a top surface of the gap  322 A. Accordingly, the gap may include one or more center pillars  332 , which assist to keep the top surface of the gap spaced from the substrate. The center pillars  332  are shown to be rectangular in shape, but can be a linear rib extending in the Y-axis. Alternatively, a rib may extend across a width of the gap  322  in the X-axis. 
       FIG. 4  illustrates a configuration of beams of a MEMS device from a top view of the MEMS device according to another exemplary embodiment of the present invention. The exemplary MEMS device  400  comprises an anchor  410 , a plurality of hinges  412 , a plurality of beams  415 , a plurality of slots  417  and beam connection cross members  419 . The slots  417  can be located between adjacent beams  415 . When experiencing the stress of thermal loads, the illustrated configuration allows for expansion of a portion of the beams  415  into the slots  417 . The beam connection cross members  419  connect adjacent beams  415  to one another and provide support of the beams  415  to provide structural support by minimizing, for example, any possible rotation, tilting or twisting of the beams  415 . The beam cross connection members  419 , although shown centered on beams  415 , may be located at any point along the beams  415  in the Y-axis. 
       FIGS. 5A and 5B  illustrate a buttress configuration of an anchor from a cross sectional view and from a top view of a MEMS device, respectively, according to an exemplary embodiment of the present invention. The cross section of  FIG. 5A  is taken at sectional  5 A shown in  FIG. 5B . The MEMS device  500  comprises a substrate  510  and a switch  520 . The switch  520  comprises an anchor  521 , a gap  522 , a hinge  523 , a beam  525  and a tip  527  similar to those discussed above with respect to  FIGS. 1-4 . The anchor  521  further comprises a buttress  532 . As illustrated in  FIG. 5A , the buttress  532  extends from the top e of the anchor  521  to the substrate  510 , and is on the side of the anchor  521  closer to the hinge  523  and beam  525 . 
     In the absence of the buttress  532 , the material forming the top (i.e., the highest point in the Z-axis) of the anchor  521  can expand, when subject to the thermal stresses, in the direction of the beam  525  resulting in a rolling action of the anchor  521 . The rolling action may be toward the beam  525 . The buttress  532  serves to allow for expansion of the anchor  521 , but also serves to block the rolling forward of the anchor  521  and the resulting sagging of the beam  525 . The additional mass provided by the buttress  532  of the anchor  521  assists in limiting the amount of expansion. 
     Although shown in  FIG. 5B  as two buttresses aligned side-by-side in a horizontal direction, the buttress  532  can, alternatively, be aligned one-above-the-other in a vertical direction. Of course, the buttress  532  be a single buttress or more of the same or different sizes and shapes. Furthermore, as illustrated the buttress  532  is shown having a rectangular shape, however, the buttress can have  532  any shape such as curved, saw-toothed, sinusoidal, polygonal and the like, suitable for providing additional structural support for mitigating distortion within the MEMS device  500 . 
     Also shown in  FIG. 5B  are beam connection cross members  539  that connect beams  525 . Although shown substantially at the midpoint of the beams  525 , the beam connection cross members  539  may be located at any point along the beam  525  between the tip  527  and hinge  523 . The beam connection cross members  539  may act to provide a restoring force to the beams  525 , thereby aiding in maintaining proper positioning of the beams  525 . Locating the beam connection cross members  539  closer to the tip provides additional stress relief, and allows the material from which the beams  525  is formed to expand into beam slots  537 . 
       FIG. 6  illustrates a top-view of a configuration of a beam of a MEMS device according to another exemplary embodiment of the present invention. In the embodiment illustrated in  FIG. 6 , the MEMS device  600  comprises a substrate  605 , an anchor  621 , a hinge  623 , a beam  625 , a tip  627  and an optional beam connection cross member  624 . The beam  625  has a length that is reduced in comparison to the beams illustrated in the embodiments of  FIGS. 1-5 . It is preferable that the beam  625  have a length of approximately 50 micrometers, which is less than the length of the beam s in the embodiments of  FIGS. 1-5 . The beams  625  in the embodiments of  FIGS. 1-5  are approximately 100 micrometers. The reduced length and reduced mass of the beam  625  of the present embodiment facilitates a structurally more rigid beam with less beam cantilevered from the hinge  623 . The reduced cantilever reduces stress on the hinge  623  thereby limiting the effects of any thermal expansion. 
     In addition, the width W 1  of beam  625  may also vary and the width W 2  may also vary. The width W 1  may be either greater or equal to the width W 2 . Furthermore, the optional beam connection cross members  624 , if present, do not have to be centered on the beams  625 , but may be located at any point along the beam  625  either closer to tip  627  or closer to hinge  623 . In addition, the locations or absence of optional beam connection cross members  624  may alternate from one beam to the next beam across MEMS device  600 . 
       FIG. 7  is a top-view of a configuration of the anchor of a MEMS device according to an exemplary embodiment of the present invention. The MEMS device  700  comprises a substrate  705  and an anchor  710 . The anchor  710  includes anchor slots  715  and beam  720 . The beam  720  interfaces with the anchor  710  via the hinge  719 . The anchor slots  715  reduce the amount of mass of the anchor  710 , thereby limiting the amount of material that can expand. In addition, the anchor  710  can expand into the anchor slots  715 . This reduces the distortion of the anchor  710  and the hinge  719  and, as a result, reduces the tilting, either down or up, of the beams  720 . 
     The anchor slots  715  are preferably substantially aligned with hinges  719 , and extend to the substrate  705 . Of course, the dimensions of the anchor slot  715  may vary from wider to narrower and vice versa in all directions, i.e., top-to-bottom or bottom-to-top. In addition, the shape of the anchor slot  715  does not have to be rectangular, but can be circular, polygonal, cylindrical, triangular or any shape that provides suitable stress-relieving properties, nor do the anchor slots  715  have to be of uniform size. It is also envisioned that the anchor slots  715  can be various shapes and sizes, or uniform shapes and sizes, or a combination of both in the exemplary embodiments. Furthermore, the anchor slot  715  does not have to be a single slot aligned with the hinge  720 , but can be a plurality of anchor slots  715  substantially aligned with the hinge  720  or in a number of different locations in the anchor  710 , or a combination of both. The anchor slot  715  does not have to be located directly behind hinge  719 . By minimizing the mass of the anchor  710 , the gold or other material, from which the anchor  710  is made, does not expand as much. Furthermore, the anchor slots  715  provide additional space into which the gold or other material can expand. 
     In another embodiment, the anchor  821  includes a U-shaped anchor slot  815 . In  FIG. 8 , the MEMS device  800  comprises a switch  820  and an anchor  821 . The switch  820  comprises an anchor beam interface  825 , a hinge  823 , a beam  826 , a beam cross connection member  824 ; a tip  827  and an anchor airbridge tie  830 . The anchor beam interface  825  is the attachment point for the hinge  823  to the anchor  821 . The hinge  823  extends, in the Y axis, between the anchor beam interface  825  to connect with beam  826  including expansion hole  828 . The beam  826  is connected to an adjacent beam  826 A by a beam cross connection member  824 . As illustrated, switch  820 A can be connected to yet another switch  820 B by another beam cross connection member  824 A, which in turn is connected to a further switch  820 C. 
     Due to the high heat that the switch  820  experiences during manufacturing and operation, the anchor  821  and other portions of switch  820  may expand and may reduce the size of the U-shaped anchor slot  815 , this aids in preventing warping and other detrimental effects to the beam  826 . Thereby allowing the MEMS device  800  to operate properly. Cross connection member  824  connects switch  820  to switch  820 A at beam  826  and beam  826 A. Switch  820 A comprises, similar to switch  820 , a common anchor  821 , an anchor slot  815 A, a beam  826 , a hinge  823 , a beam interface  825 A, and a tip  827 . Switches  820 B and  820 C are similarly constructed. The beam cross connection member  824  improves the structural stability of the beams by aiding in mitigating the effects of the thermal expansion to which the MEMS devices are subjected. Beam cross connection members  824  and  824 A may have different positions from beam-to-beam along the beams  826  and  826 A. The position of beam cross connection members  824  and  824 A influence the dimensions of beam slot  829  located between the beams  826  and  826 A and beam slot  829 A between beams  826 A and  826 B. The length of the beam slots  829  and  829 A may be measured from the beam cross connection member  824  to the end of the beam  826  at the point where hinge  823  interfaces with the beam  826  in the Y-axis. Positioning the beam cross connection member  824  closer to the end of the beam  826  near tip  827  mitigates the thermal effects and stresses on hinge  823  better than positioning the beam cross connection member  824  closer to the hinge  823 . As shown in  FIG. 8 , the beam cross connection members  824  and  824 A may alternately be positioned further away from hinge  823  when connecting beam  826  to beam  826 A, and closer to hinge  823 A when connecting beam  826 A to beam  826 B. Additionally, beam cross connection members  824  and  824 A aid in providing a restoring force to the beams  826  and  826 A to maintain proper alignment and tip  827  displacement. The dimensions of beam cross connection members  824  and  824 A in the X-axis may also be approximately 2-25 micrometers. The sectional view A illustrates the structure of the beam interface  825 A and the anchor  821 . Illustrated with the switch removed, the configuration of the anchor  821  comprises U-shaped anchor slots  815  and an anchor airbridge tie  830  is shown. 
       FIG. 9  illustrates a plan view of an exemplary configuration of a slotted anchor and an anchor airbridge tie according to an embodiment of the present invention. The MEMS device  900  comprises a switch  920  and an anchor  921 . The anchor  921  includes at least one anchor slot  915 , and at least one anchor section  921 A, at least one anchor section  921 B, and at least one anchor airbridge tie  930 . For purposes of the following discussion, beam  920  is shown in dashed lines since the focus of the discussion is the anchor  921 , anchor slot  915  and the anchor airbridge tie  930 . The anchor airbridge tie  930  spans anchor slot  915  tying together anchor sections  921 A and  921 B. An air gap can also be located beneath the anchor airbridge tie  930  to further increase space for thermal expansion of materials into anchor slot  915 . 
     This structure can be formed of dual layers of gold. The beam  920  can be formed of gold and have a thickness of approximately 6 micrometers, while the anchor  921  can also be formed of gold and have a thickness of approximately 2 micrometers. This dual-thickness, dual layer configuration results in differing amounts of thermal expansion for the beam  920  as compared to the anchor  921 . These dimensions are exemplary for purposes of discussion, and the exemplary embodiments are not limited to these dimensions. Of course, other materials or combinations of materials may be used to form the anchor, anchor airbridge tie, hinge and beam. 
     The anchor airbridge tie  930  may provide structural rigidity to the anchor  921  thereby allowing for thermal expansion of the gold material and mitigates warping of the beam  920 . An additional feature of the embodiment shown in  FIG. 9  is a beam  920  that has the same dimensions as the anchor  921 , and can function without a hinge element. 
       FIG. 10  illustrates a detailed sectional view of the exemplary anchor airbridge tie  930  shown in  FIG. 9  according to an embodiment of the present invention. 
     Sectional view A of the MEMS device  1000  shows in detail an exemplary anchor  1021  and exemplary beam interface  1025 . The anchor  1021  may be formed in various shapes, such as a U-shape or rectangular blocks, and comprises an anchor slot  1015 , an anchor  1021 , and anchor airbridge tie  1030 . The anchor  1021  may include anchor sections  1021 A,  1021 B and, depending upon its configuration, optional anchor section  1021 C. When the anchor slot  1015  is U-shaped, the anchor section  1021 C may be integral with anchor sections  1021 A and  1021 B to form a monolithic anchor  1021 . Alternatively, the individual anchor sections  1021 A,  1021 B and  1021 C may be formed separately and configured as shown. The beam interface  1025  spans over the anchor airbridge tie  1030  and is supported by anchor sections  1021 A and  1021 B. 
     Anchor slot  1015  may be formed with an open end on both sides of the anchor sections  1021 A and  1021 B, and separates anchor section  1021 A from anchor section  1021 B. When the anchor  1021  is formed with only anchor sections  1021 A and  1021 B, the anchor airbridge tie  1030  connects the anchor section  1021 A with anchor section  1021 B by spanning anchor slot  1015 . This forms a shape similar to the letter H. Optionally, the anchor slot  1015  may be formed to have a U-shape when anchor section  1021 C fills the gap between anchor section  1021 A and anchor section  1021 B. 
     The dimensions of anchor airbridge tie  1030  may vary. As shown in  FIG. 10 , the anchor airbridge tie  1030  includes tie extension  1030 A and tie wall  1030 B. The width W of the anchor airbridge tie expansion  1030 A can be varied to account for differences in the dimensions of a beam, a hinge, a hinge interface  1025 , a beam cross connection member, an anchor or any combination thereof as well as to account for the thermal expansion of different materials used to construct a MEMS device  1000 . The adjustment in width W is preferably in the Y-axis. However, adjustments in the X- or Z-axis can also provide substantial results. In addition, the length L of the tie wall  1030 B may also be varied to provide additional stress relief properties to the beam and the hinge interface  1025 . Further adjustments of the position of anchor bridge tie  1030  in the Y-axis with similar adjustments to the hinge interface  1025  along the anchor sections  1021 A and  1021 B may be made for a variety of reasons, such as providing additional stress relief or thermal properties. In one embodiment, the anchor airbridge tie extension  1030 A may be located at an upper most location on the Y-axis, in close proximity to the beam, such that the tie extension  1030 A and the tie walls  1030 B form an inverted U-shape. The width of both the tie extension  1030 A or the tie walls  1030 B may vary. 
       FIG. 11  illustrates a top-view of an exemplary configuration of a beam of a MEMS device according to yet another embodiment of the present invention. 
     The configuration of MEMS device  1100  comprises anchors  1121  and beams  1120 . The beams  1120  together form a flat spring having a thickness (in the Z-axis) of approximately 2-10 micrometers. The beam  1120  comprises a tip  1127 , a hinge  1123 , a beam cross connection member  1124  and a beam interface  1125 . Similar to a spring, the beam  1120  expands and contracts according to the thermal expansion (and contraction) of the MEMS device  1100 . Due to the beam thermal expansion slots  1117  can fill with gold as the gold forming the beams  1120  expand. The beam connection cross members  1124  can also expand into the beam thermal expansion slots  1117 . In addition, the beam connection cross members  1124  provide additional structural support to maintain the alignment of tip  1127  with the contacts at the base (not shown). The flat spring shape of the beams  1120  is maintained by the beam cross connection members  1124 , and the flat spring shape distributes stress throughout the beams  1120 . Stress being equal to force over area. The beams  1120  expand into the beam thermal expansion slots  1117  which further reduces stress because the thermal expansion slots  1117  enable the material to move according to the force induced by the stress caused by thermal expansion. The beam cross connection members  1124  may also act to keep the individual beams  1120  from splitting apart. To maximize the stress reduction properties of this configuration, the beams  1120  of MEMS device  1100  are symmetrical around line  1190 , which bisects the MEMS device  1100 . Of course, asymmetrical beam configurations are also envisioned, and may provide stress reduction properties as well. Although MEMS device  1100  is shown with three hinges  1123 , more or less hinges  1123  may be used. 
       FIG. 12  illustrates a method for producing a switch according to an exemplary embodiment of the present invention. The exemplary method of manufacturing or constructing a micro-electro-mechanical device will be described with reference to  FIG. 12 . In step  1210 , a substrate is formed having a plurality of electrical connections including a source connection, a gate connection and a drain connection. An anchor is affixed, at step  1220 , to the substrate at a first point and a second point. The anchor can be electrically connected, at step  1230 , to the source connection. In step  1240 , a gap is formed at a location between the first point and the second point. A movable hinge is connected, at step  1250 , to the anchor at a point diagonally opposite the gap in the anchor. At step  1260 , a beam is connected to the hinge, the beam having a width that is wider than the hinge, and configured to move when a voltage is applied to the gate connection. Step  1270  includes connecting a contact tip to the beam, opposite the hinge, that electrically contacts the drain connection thereby forming a current path formed from the source connection to the drain connection, when the beam moves in response to a voltage applied to the gate connection. 
     In yet another embodiment, the anchor beam interface  1325  may be configured differently. In  FIG. 13 , the MEMS device  1300  comprises a switch  1320  and an anchor  1321 . The switch  1320  comprises an anchor beam interface  1325 , a hinge  1323 , a beam  1326 , a beam cross connection member  1324 , and a tip  1327 . The anchor beam interface  1325  may be the attachment point for the hinge  1323  to the anchor  1321 . The hinge  1323  may extend, in the Y axis, between the anchor beam interface  1325  to connect with beam  1326 . The beam  1326  is connected to an adjacent beam  1326 A by a beam cross connection member  1324 . As illustrated, switch  1320 A may be connected to yet another switch  1320 B by another beam cross connection member  1324 A, which in turn is connected to a further switch  1320 C. 
     Due to the high heat that the switch  1320  experiences during manufacturing and operation, the anchor  1321  and other portions of switch  1320  may expand and may reduce the size of the U-shaped anchor slot  1315 , this aids in preventing warping and other detrimental effects to the beam  1326 . Thereby allowing the MEMS device  1300  to operate properly. Cross connection member  1324  connects switch  1320  to switch  1320 A at beam  1326  and beam  1326 A. Switch  1320 A comprises, similar to switch  1320 , a common anchor  1321 , an anchor slot  1315 A, a beam  1326 A, a hinge  1323 A, an anchor beam interface  1325 A, and a tip  1327 . Switches  1320 B and  1320 C are similarly constructed. The beam cross connection member  1324  improves the structural stability of the beams by aiding in mitigating the effects of the thermal expansion to which the MEMS devices are subjected. Beam cross connection members  1324  and  1324 A may have different positions from beam-to-beam along the beams  1326  and  1326 A. The position of beam cross connection members  1324  and  1324 A influence the dimensions of beam slot  1329  located between the beams  1326  and  1326 A and beam slot  1329 A between beams  1326 A and  1326 B. The length of the beam slots  1329  and  1329 A may be measured from the beam cross connection member  1324  to the end of the beam  1326  at the point where hinge  1323  interfaces with the beam  1326  in the Y-axis. Positioning the beam cross connection member  1324  closer to the end of the beam  1326  near tip  1327  mitigates the thermal effects and stresses on hinge  1323  better than positioning the beam cross connection member  1324  closer to the hinge  1323 . The beam cross connection members  1324  and  1324 A may alternately be positioned further away from hinge  1323  when connecting beam  1326  to beam  1326 A, and closer to hinge  1323 A when connecting beam  1326 A to beam  1326 B. Alternatively, the beam cross connection members  1324  and  1324 A may extend the entire length of the beam  1326  and  1326 A, respectively. Additionally, beam cross connection members  1324  and  1324 A aid in providing a restoring force to the beams  1326  and  1326 A to maintain proper alignment and tip  1327  displacement. The dimensions of beam cross connection members  1324  and  1324 A in the X-axis may also be approximately 2-25 micrometers. The sectional view A illustrates the structure of the anchor beam interface  1315 A and the anchor  1321 . Illustrated with the switch removed, the configuration of the anchor  1321  comprises U-shaped anchor slots  1315 A is revealed. In the illustrated embodiment, the anchor beam interface  1325  has a similar thickness to the hinge  1323 . 
     In a further embodiment, the anchor beam interface  1325  may be built up to allow for expansion in a manner that prevents distortion of the beam and the resultant change in distance between the contact tip and the contact on the substrate. As illustrated in  FIG. 14 , the MEMS device structure  1400  comprises a switch  1420 , a substrate  1450  and conductor paths  1441 ,  1443  and  1445 . The switch  1420  comprises an anchor  1421 , a hinge  1423 , an anchor beam interface  1425 , an anchor beam interface end  1425 A, a beam  1426 , and a contact tip  1427 . The anchor  1421  may be a separate layer of conductive material, such as gold, that is in contact with a conductor path  1441  and/or a substrate  1450 . The anchor  1421  may have a first thickness, such as approximately 2 micrometers. The anchor  1421  may have anchor slots  1415 , which extend through the anchor  1421 , to provide area for thermal expansion of the anchor  1421 . The anchor beam interface  1425  on the anchor  1421  may have a second thickness that may be a number of times thicker greater than the first thickness of the anchor  1421 , and may measure approximately 6 micrometers. The anchor beam interface  1425  may be configured to provide tilt displacement, which is displacement in either the up or down direction at the contact tip  1427 . The hinge  1423  may or may not be offset from the anchor beam interface  1425  at the anchor beam interface end  1425 A. The top edge of the hinge  1423  may or may not be co-planar with the top edge of the anchor beam interface end  1425 A. The beam  1426  and the contact tip  1427  may be arranged as discussed in previous embodiments. The conductor paths  1441 ,  1443  and  1445  provide respective paths to the source, gate and drain connection points of the MEMS device  1420 . 
       FIG. 15  provides a cross-sectional view of the switch device illustrated in  FIG. 14 . The MEMS device  1500  may include the switch  1520 , the substrate  1540 , and conductor paths  1541 ,  1543  and  1545 . The switch  1520  may include an anchor  1521 , an anchor beam interface  1525 , a hinge  1523 , and a beam  1526 . 
     The anchor  1521  may have a thickness B, which may be approximately 2 micrometers. The anchor  1521  may have an air gap  1521 - 3  that may have a width that allows for thermal expansion of the anchor material, which may be gold. The anchor  1521  may be configured to allow for an offset between the anchor beam interface  1525  and the hinge  1523 . The offset may allow the beam  1523  to be located approximately 0.6 micrometers above the substrate  1530  and conductor paths  1543  and  1545 . Although the offset between the anchor beam interface  1525  and the beam  1523  is also shown in  FIG. 15  at the top of the beam and the anchor beam interface, the tops of the anchor beam interface  1525  and the beam  1523  may not have an offset, and may be co-planar in a horizontal plane (through the Z-axis). 
     The anchor beam interface  1525  may be formed from a conductive material, such as gold, and may have a thickness A. The thickness A may be approximately 6 micrometers. The configuration of the anchor beam interface  1525  allows for thermal expansion of the anchor beam interface  1525  all directions upwards from the anchor  1521 . 
       FIG. 16  illustrates a top-view of an exemplary configuration of a switch comprising a MEMS device according to yet another embodiment of the present invention. An exemplary operation of the MEMS device  1600  will be described with reference to  FIG. 16 . The exemplary MEMS device  1600  includes a switch  1620 , a substrate  1630 , and conductor paths  1641 ,  1643  and  1645 . The top view of an exemplary MEMS device  1600  illustrated in  FIG. 16  shows the layout of the conductor paths  1641 ,  1643  and  1645 . The switch  1620  comprises anchor  1621 , anchor beam interface  1625 , beam assembly  1626 , and contact tips  1627 . The anchor  1621  makes contact with conductor path  1641 . When the MEMS device  1600  is actuated by a signal present on conductor  1643 , the switch  1620  responds with the beam assembly  1626  moving so contact tips  1627  contact conductor path  1645 . This closes an electrical path between conductor path  1641  and conductor path  1645 . Of course, other conductor path configurations may be possible. 
       FIG. 17  illustrates a sectional view of an exemplary configuration of the beam and anchor of a MEMS device according to another embodiment of the present invention. The MEMS device  1700  comprises an anchor  1721 , a substrate  1740 , anchor beam interface  1725 , and a hinge  1723 . For ease of illustration and discussion, other components similar to those described with respect to other embodiments, for example, the beam and contact tips, are also included in this embodiment. 
     In the illustrated embodiment, anchor  1721  further comprises an airbridge  1750 . The airbridge  1750  may be an opening between the substrate  1740  and the anchor  1721  that extends from the anchor gap  1715  beneath the anchor beam interface  1725  to the hinge  1723 . The airbridge  1750  may have a dimension C, which may be, for example, approximately 0.60 micrometers. The airbridge  1750  may also cause the center portion of the anchor beam interface  1725  to rise above the edges as illustrated by notches  1725 - 9  located on both sides of the top of anchor beam interface  1725 . Of course, the dimensions of the airbridge  1750  in anchor  1721  may vary from wider to narrower and vice versa in all directions, i.e., front (anchor gap  1715 ) to rear (hinge  1723 ), rear to front, up (toward anchor beam interface  1725 ) to down (toward substrate  1740 ) or down to up. In addition, the shape does not have to be rectangular, but may be semi-circular, triangular, saw-toothed or any shape that provides suitable stress-relieving properties. The presence of airbridge  1750  may provide yet another area for expansion of the anchor beam interface  1725  and the anchor  1721 . 
       FIG. 18  illustrates a cross-sectional view of an exemplary configuration of the beam and anchor of a MEMS device according to another embodiment of the present invention. The MEMS device  1800  comprises a substrate  1840 , and a switch  1820 . The switch  1820  may comprise an anchor  1821 , an anchor beam interface  1825 , a hinge  1823 , and a beam  1826 . The anchor  1821  comprises an anchor slot  1815 , and an airbridge  1850 . The airbridge  1850 , as explained above with respect to  FIG. 17 , may extend from the anchor slot  1815  through the anchor  1821  to the bottom edge of the hinge  1823 , thereby forming an opening between a portion of the anchor  1821  and the substrate  1840 . The airbridge  1850  may also cause the center portion of the anchor beam interface  1825  to rise above the edges as illustrated by notches  1825 - 9  located on both sides of the top of anchor beam interface  1825 . The notches  1825 - 9  may or may not be present. The airbridge  1850  opening may have a dimension C of approximately 0.60 micrometers, which may not be uniform as explained above with respect to  FIG. 17  and depending upon the shape of the airbridge. 
     The anchor beam interface  1825 , the hinge  1823  and beam  1826  have a thickness A, which may be approximately 6.0 micrometers. Due to the anchor  1821  located below the anchor beam interface  1825 , the top edge of the hinge  1823  and the beam  1826  may be offset from the top edge of the anchor beam interface  1825 . When subject to expansion the anchor beam interface  1825  may expand into the opening formed by the airbridge  1850 . This additional area for expansion further mitigates the distortion of the switch  1820  when subject to thermal effects due to operation and the environment. 
     The gap D between substrate  1840  and the hinge  1823  and the beam  1826  may have a dimension of approximately 0.60 micrometers. In the illustrated embodiment, the dimensions of the airbridge opening C may be equal to the dimension gap D. 
     Those skilled in the art can appreciate from the foregoing description that the present invention can be implemented and constructed in a variety of forms. Therefore, while the embodiments of this invention have been described in connection with particular examples thereof, the true scope of the embodiments of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and following claims.