Stress bimorph MEMS switches and methods of making same
2 Assignments
0 Petitions
Accused Products
Abstract
A micro-electromechanical system (MEMS) switch formed on a substrate, the switch comprising a transmission line formed on the substrate, a substrate electrostatic plate formed on the substrate, and an actuating portion. The actuating portion comprises a cantilever anchor formed on the substrate and a cantilevered actuator arm extending from the cantilever anchor. Attraction of the actuator arm toward the substrate brings an electrical contact into engagement with the portions of the transmission line separated by a gap, thus bridging the transmission line gap and closing the circuit. In order to maximize electrical isolation between the transmission line and the electrical contact in an OFF-state while maintaining a low actuation voltage, the actuator arm is bent such that the minimum separation distance between the transmission line and the electrical contact is equal to or greater than the maximum separation distance between the substrate electrostatic plate and arm electrostatic plate.
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Citations
68 Claims
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1-19. -19. (canceled)
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20. A method for minimizing capacitive coupling between elements of a micro-electromechanical switch formed on a substrate, said method comprising:
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forming a substrate electrostatic plate on said substrate;
forming a transmission line on said substrate, said transmission line having a gap forming an open circuit;
forming an actuating portion, said actuating portion comprising;
a cantilever anchor formed on said substrate; and
a cantilevered actuator arm extending from said cantilever anchor above said substrate, said actuator arm having an arm electrostatic plate formed thereon, said actuator arm having an electrical contact facing said transmission line, wherein when said switch is in an open position said actuator arm has a bend such that a minimum separation distance between said transmission line and said electrical contact is greater than or equal to a maximum separation distance between said substrate electrostatic plate and said arm electrostatic plate, whereby capacitive coupling between said transmission line and said electrical contact is minimized by maximizing the distance between said transmission line and said electrical contact formed on said actuator arm. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 65, 66)
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28. A method of fabricating an electromechanical switch on a substrate comprising the steps of:
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a) applying electrically conductive material to said substrate to form a substrate electrostatic plate region, an input transmission line region, and an output transmission line region, said regions being electrically isolated from one another;
b) depositing one or more sacrificial layers over said regions;
c) forming an electrical contact region on said one or more sacrificial layers, said electrical contact region being applied above said input transmission line region and said output transmission line region and said electrical contact region comprising electrically conductive material;
d) forming an actuating arm on said one or more sacrificial layers, said actuating arm contacting said substrate at a first end and contacting said second layer of electrically conductive material at a second end;
e) forming an arm electrostatic plate region on said actuating arm, said arm electrostatic plate region being disposed above said substrate electrostatic pate plate region and comprising electrically conductive material; and
f) removing said one or more sacrificial layers, wherein said steps of forming an actuating arm and/or forming an arm electrostatic plate region are performed to induce nonuniform stress in said actuating arm so that actuating arm will bow upwards when the one or more sacrificial layers are removed. - View Dependent Claims (29, 30, 31, 32, 67, 68)
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33. A micro-electromechanical switch formed on a substrate comprising:
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a substrate transmission line formed on said substrate, said substrate transmission line having a gap forming an open circuit;
a substrate electrostatic plate formed on said substrate; and
an actuating portion, said actuating portion comprising;
a cantilever anchor formed on said substrate;
a cantilevered actuator arm extending from said cantilever anchor, said actuator arm having an upper side and a lower side;
a conducting transmission line formed on said upper side of said actuator arm, said conducting transmission line having one or more conducting dimples projecting through said actuator arm and positioned facing said transmission line gap; and
an arm electrostatic plate formed on said actuator arm, said arm electrostatic plate having a first portion formed proximate said cantilever anchor and a second portion extending from said first portion along said actuator arm, wherein when said switch is in an open position, said actuator arm has a bend such that a minimum separation distance between said substrate transmission line and said one or more conducting dimples is equal to or greater than a maximum separation distance between said substrate electrostatic plate and said arm electrostatic plate, said arm electrostatic plate and a segment of said actuator arm on which said arm electrostatic plate is formed defining a structure electrostatically attractable toward said substrate electrostatic plate upon selective application of a voltage to said arm electrostatic plate. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41)
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43. A method of fabricating an electromechanical switch on a substrate comprising the steps of:
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a) forming a first layer of electrically conductive material over a surface of said substrate, said first layer comprising an arm plate contact region, a substrate electrostatic plate region, an input transmission line region, and an output transmission line region, wherein each of said regions is electrically isolated from other said regions;
b) depositing a sacrificial layer over said first layer of electrically conductive material;
c) forming an arm structural layer, said arm structural layer providing a cantilever with a proximate end and a distal end, said distal end located above said input transmission line region and above said output transmission line region, said cantilever having a cantilever anchor and a cantilever arm, said cantilever anchor formed at said proximate end and located above said arm plate contact region, said cantilever arm projecting from said cantilever anchor to said distal end and located above said substrate electrostatic plate region;
d) removing a portion of said arm structural layer at said distal end to create a dimple area above said input transmission line region and said output transmission line region;
e) removing a portion of said arm structural layer at said cantilever anchor to expose said arm plate contact region;
f) depositing a layer of metal on said arm structural layer, said layer of metal filling said dimple area and said layer of metal providing an arm electrostatic plate electrically connected to said arm plate contact region, said arm electrostatic plate located generally above said substrate electrostatic plate region; and
g) removing said sacrificial layer, wherein the step of forming the arm structural layer is performed to induce stress in the arm structural layer that varies from the stress of the layer of metal deposited on the arm structural layer so that the cantilever arm will bow upwards when the sacrificial layer is removed. - View Dependent Claims (44, 45, 46, 47)
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48. A micro-electromechanical switch formed on a substrate comprising:
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a substrate transmission line formed on said substrate, said substrate transmission line having a gap forming an open circuit;
a substrate electrostatic plate formed on said substrate; and
an actuating portion, said actuating portion comprising;
a cantilever anchor formed on said substrate;
a cantilevered actuator arm having a proximate end and a distal end, said cantilevered actuator arm attached to the cantilever anchor at the proximate end of the cantilevered actuator arm a cantilever insulating layer attached at the distal end of the cantilevered actuator arm;
an electrical contact formed on said cantilever insulating layer and positioned facing said transmission line gap; and
an arm electrostatic plate formed on said actuator arm, said arm electrostatic plate having a first portion formed proximate said cantilever anchor and a second portion extending from said first portion along said actuator arm, wherein when said switch is an open position, said actuator arm has a bend such that a minimum separation distance between said transmission line and said electrical contact is equal to or greater than a maximum separation distance between said substrate electrostatic plate and said arm electrostatic plate, said arm electrostatic plate and a segment of said actuator arm on which said arm electrostatic plate is formed defining a structure electrostatically attractable toward said substrate electrostatic plate upon selective application of a voltage to said arm electrostatic plate. - View Dependent Claims (49, 50, 51, 52, 53, 54, 55, 56, 57, 58)
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59. A method of fabricating an electromechanical switch on a substrate comprising the steps of:
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a) depositing a first layer of electrically conductive material over a surface of said substrate;
b) depositing a sacrificial cantilever support layer over said first layer of electrically conductive material;
c) forming a arm structural layer of electrically conductive material over said sacrificial cantilever support layer, said arm structural layer having a proximate end and a distal end, said arm structural layer having a cantilever anchor disposed at said proximate end, said cantilever anchor formed on said surface of said substrate, and said arm structural layer having a cantilever arm projecting from said cantilever anchor;
d) depositing a first metal layer on said cantilever arm, said first metal layer located generally above said first layer of electrically conductive material;
e) depositing a second metal layer on or above said substrate to form a transmission line with a gap in the middle, said second metal layer located adjacent said distal end;
g) depositing a conductor sacrificial layer on top of said second metal layer;
h) depositing a third metal layer on top of said conductor sacrificial layer, said third metal layer positioned above said second metal layer and extending across said gap;
i) forming an insulating layer above said third metal layer and located adjacent said distal end, said insulating layer attaching to said distal end and to said third metal layer; and
j) removing said sacrificial layers, wherein the step of forming the arm structural layer is performed to induce stress in the arm structural layer that varies from the stress of the first layer of metal so that the cantilever arm will bow upwards when said sacrificial layers are removed. - View Dependent Claims (60, 61, 62, 63, 64)
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Specification