Design and Finite Element Method Analysis of Laterally Actuated Multi-Value Nano Electromechanical Switches
We report on the design and modeling of novel nano electromechanical switches suitable for implementing reset/set flip-flops, AND, NOR, and XNOR Boolean functions. Multiple logic operations can be implemented using only one switching action enabling parallel data processing; a feature that renders t...
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| Published in: | Japanese Journal of Applied Physics Vol. 50; no. 9; pp. 094301 - 094301-9 |
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| Main Authors: | , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
The Japan Society of Applied Physics
01-09-2011
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| Online Access: | Get full text |
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| Summary: | We report on the design and modeling of novel nano electromechanical switches suitable for implementing reset/set flip-flops, AND, NOR, and XNOR Boolean functions. Multiple logic operations can be implemented using only one switching action enabling parallel data processing; a feature that renders this design competitive with complementary metal oxide semiconductor and superior to conventional nano-electromechanical switches in terms of functionality per device footprint. The structural architecture of the newly designed switch consists of a pinned flexural beam structure which allows low strain lateral actuation for enhanced mechanical integrity. Reliable control of on-state electrical current density is achieved through the use of metal-metal contacts, true parallel beam deflection, and lithographically defined contact area to prevent possible device welding. Dynamic response as a function of device dimensions numerically investigated using ANSYS and MatLab Simulink. |
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| Bibliography: | Architecture of conventional NEM switches: (a) Cross sectional view of vertically actuated NEM switch based on metal--oxide contact, where the deflection is in the out-of-plane direction and (b) Top view of a laterally actuated NEM switch, where the deflection is in the in-plane direction. View of the two-values complementary switch controlled by two actuation electrodes displaced from the contact beam by certain gap larger than the one displaced the contact pads: (a) top view and (b) cross-sectional view. Inverted reset/set flip-flop is realized by connecting the anchor to the $V_{\text{DD}}$ source which is equivalent to the logical value 1, and applying the input logical signals at the ports VA and VB. Logic gates AND, NOR, and XNOR. The three functions are implemented simultaneously on the same device considering the inverted inputs of VA and VB. Lumped parameter model of the two-values complementary NEM switch, consists of electrical part: the actuation voltage sources and the variable capacitors, and the mechanical part: the mass, mechanical suspension, damper and mechanical stopper. Simulink model of the two-values complementary switch: consists of mechanical forces due to the mass-spring-damper system and mechanical stopper, and the electrostatic force due to the applied electrical voltage across the capacitor. FEM modeling. (a) Structural-electrostatic model using transducer element (TRANS126) as the coupled field element. (b) Mechanical deformation at 3.75 V applied at the top part of the switch, with initial gap of 50 nm, the maximum deflection is 50 nm, which results in electrical short circuit. (c) Mechanical deformation at 5.15 V applied at the top part of the switch, with initial gap of 60 nm. The deflection at the edges represents the overlapping area with the contact pads, this deflection value is 32 nm. The maximum deflection is 32.525 nm at the middle of the contact beam, which is less than the possible maximum deflection of 60 nm, for avoiding the electrical short circuit. Switching voltage response. The solid line represents the analytical deflection response under different voltages values. The small dotted line shows the maximum deflection of the switch which is 32 nm. The dashed line shows the FEM solution for the pull-in voltage starts at 5.15 V comparable with 4.93 V from the analytical solution, and the large dotted line shows the FEM solution of the release voltage is at 4.55 V comparable with 4.36 V from the analytical solution. Transient responses. The switching time delay of 64 ns is affected by the mechanical bouncing such that the total time delay is 867.5 ns. The scaling effect on the time delay of the switch at pull-in voltage of 4.93 V. The scaling down of the switch significantly reduces the switching time delay, such that minimum time delay of 38 ns is achievable with 11 nm technology. Actuation voltage effect on the time delay and the mechanical bouncing. The increase of the actuation voltage reduces the time delay to 22 ns, the total delay with mechanical bouncing to 229 ns. The complementary switching for several periods at 10 V. The deflection of the contact beam from $-32$ nm (downward) to 32 nm (upward), which shows larger mechanical bouncing effect due to the larger beam deflection. |
| ISSN: | 0021-4922 1347-4065 |
| DOI: | 10.1143/JJAP.50.094301 |