A push-pull double-contact MEMS relay fabricated by MetalMUMPs process

Abstract

pull movements of leverages and torsion springs, high isolations (Hah et al. 2000) or high C off /C on ratio (Rangra et al. 2005) or high power handing (Song et al. 2012) MEMS relays are demonstrated. By using magnetostatic latching and electrothermal actuation, a bistable push-pull MEMS switch with lower power consumption is reported (Wu et al. 2010). However, the toggle and the leverage structures of these push-pull MEMS relays are not only hard to process but also complex to control.To retain the advantages of the push-pull method while avoiding its disadvantages, a push-pull double-contact MEMS relay is designed and fabricated by the MetalMUMPs process. The thick nickel MetalMUMPs process, chosen here, is very suitable for complicated in-plane moving structures (Cao et al. 2007;Almeida et al. 2007). In Sect. 2, the configuration and the principle of the MEMS relay is proposed. Contents in Sect. 3 describe the measurement and the verification of the MEMS relay. Finally, conclusion is given in Sect. 4. Configuration and principleThe schematic view of the push-pull double-contact MEMS relay is shown in Fig. 1. The MEMS relay consists of four moveable beams, four electrostatic-driven actuators, two contact parts, one DC bias line and input/output AC ports. Both AC ports are anchored to substrate and are connected to the movable beams. The end of each moveable beam is connected and driven by a differential parallel plate actuator. The four actuators share one electrode which is connected to the DC bias pad. The other electrodes of the four actuators are connected to the left AC ports and the right AC ports, respectively.Abstract This document presents a push-pull doublecontact MEMS (Micro ElectroMechanical System) relay. The MEMS relay is electrostatic driven and laterally actuating. Two push-pull structures form two parallel contacts for the proposed MEMS relay, which can make the contact resistance of the MEMS relay be smaller. The push and pull actions of the push-pull actuators can be accomplished simultaneously using only one action signal. In addition, high inductance DC bias line and substrate removal are used for additional electrical and/or thermal isolation. The fabrication of the proposed switch is based on the standard MetalMUMPs process. The measured pull-in voltage is 116 V and the switch-ON delay is 44 μs. Contact resistance of the MEMS relay is less than 1 Ω when the stress voltage exceeds 120 V.

Fabrication of a flexible polyimide-based electrostatically actuated MEMS relay

“…Contact resistance directly influences the amount of joule heating, and in turn influences the reliability of MEMS relays, and a low contact resistance is always desirable [2,6,[25][26][27]. Song et al designed a stacked-electrode structure, a flexible polymer BCB was used as the substrate of the drain electrode, the flexible polymer significantly reduced the effective hardness of the contact material, and a minimum contact resistance of 5 mΩ was achieved [19].…”

Low voltage, high speed and small area in-plane MEMS switch

“…As shown in figure 1(d), we have integrated the combs [21] into the micro cantilever to decrease the mass and area of the device. On one hand, compared to the designs shown in figure 1(a) [12][13][14][15][16]21], the mass of the movable structure of the device was lower, and the speed response becomes better. On the other hand, compared to the cantilever designs shown in figure 1(c) [22-24, 30, 31], our design could boost the driving force, and obtain lower pull-in voltage.…”

“…Decreasing the pull-in voltage and increasing the switching speed are two attractive but contradictory research directions. As shown in figure 1(a), one effective method for the inplane actuators is adopting a large number of driving combs [12][13][14][15][16]. More combs generate a larger driving force, and the actuator can be pulled-in by lower voltage [13].…”