Parallel-contact metal-contact RF-MEMS switches for high power applications
27 Sep 2004-pp 781-784
TL;DR: In this article, a metal-contact MEMS switch element with a relatively wide and thick cantilever having two contacts was designed and tested with the aim of handling moderately high RF power (hundreds of mW to 1 W).
Abstract: Electrostatically-actuated metal-contact RF MEMS switches have been designed, fabricated and tested with an aim of handling moderately high RF power (hundreds of mW to 1 W). The design strategy is: (i) the development of a switch element having good metal contacts and reliability without stiction problems under moderate actuation voltage (50-60 V), and (ii) the reduction of RF current through each contact by arranging several mechanically-independent switch elements in parallel. The developed switch element is a relatively wide and thick cantilever having two contacts and should have a contact force of 70 /spl mu/N per each contact at an applied voltage of 60 V based on the simulation. The measured pull-down voltage of 40-50 V has been obtained. By placing several switch elements in parallel, the insertion loss can be greatly reduced, and a loss as low as 0.03 dB at 2 GHz is obtained for an 8-contact switch (i.e. 4 switch elements) with a corresponding isolation of 22 dB at 2 GHz.
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TL;DR: In this article, an mN-level contact and restoring force RF microelectromechanical system metal-contact switch exhibiting high reliability, high linearity, and high power handing for dc-40 GHz applications was presented.
Abstract: This paper presents an mN-level contact and restoring force RF microelectromechanical systems metal-contact switch exhibiting high reliability, high linearity, and high power handing for dc-40-GHz applications. The device, which is insensitive to stress and temperature effects, achieves 1.2-1.5 mN of contact force (per contact) from 80 to 90 V and 1.0 mN of restoring force (per contact). The up-state capacitance is 8 fF, resulting in an isolation of 46, 31, and 14 dB at 1, 6, and 40 GHz, respectively. Measured results show switch resistances of 1-2 Ω and a reliability of >; 100 million cycles at 2-5 W under cold switching at 100 mW under hot-switching conditions, in an unpackaged and standard laboratory environment. Furthermore, the device was tested under prolonged hold-down conditions and demonstrated excellent RF power handling (>;10 W) and dc current handling (>;1 A) capability.
92 citations
TL;DR: In this article, a new way to design MEMS (microelectromechanical system) metal contact switches for RF applications using miniature MEMS cantilevers was presented, and a single 25 × 25 μm switch was first demonstrated with a Au-to-Ru contact, Cu = 5 fF and Ron = 7 Ω at an actuation voltage of 55 V. The measured switching time is 2.2 μs and the release time is <;1 μs.
Abstract: This paper presents a new way to design MEMS (microelectromechanical system) metal contact switches for RF applications using miniature MEMS cantilevers. A single 25 × 25 μm switch is first demonstrated with a Au-to-Ru contact, Cu = 5 fF and Ron = 7 Ω at an actuation voltage of 55 V. The measured switching time is 2.2 μs and the release time is <;1 μs. The switch is robust to stress effects (residual and stress gradients) which increases its yield on large wafers. To reduce the effective switch resistance, 10-20 miniature RF MEMS switches have been placed in parallel and result in equal current division between the switches, an up-state capacitance of 30-65 fF and a down-state resistance of 1.4-1.5 Ω. Furthermore, 10-20 element back-to-back switch arrays are developed and result in a marked improvement in the reliability of the overall switching device. A series-shunt design is also demonstrated with greatly improved isolation. The device has a figure-of-merit of fc = 1/(2πRonCu) = 3.8 THz (RonCu = 42 fs).
79 citations
Cites background from "Parallel-contact metal-contact RF-M..."
...single-crystal silicon actuators, while the UCSD switches use tethers and other stress-stable designs [4], [5]....
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TL;DR: In this paper, an electrostatic RF microelectromechanical systems (MEMS) metal contact switch based on a tethered cantilever topology is presented, which has low sensitivity to stress gradients, biaxial stresses, and temperature.
Abstract: This paper presents an electrostatic RF microelectromechanical systems (MEMS) metal contact switch based on a tethered cantilever topology. The use of tethers results in a design that has low sensitivity to stress gradients, biaxial stresses, and temperature. A switch with a footprint of 160 × 190 μm2 and based on a 8-μm-thick gold cantilever with an Au/Ru contact is implemented on a high-resistivity silicon substrate and results in a total contact force of 0.8-1.2 mN at 80-90 V, a restoring force of 0.5 mN, a pull-in voltage of 61 V, an up-state capacitance of 24 fF, and an actuation time of 6.4 μ s. The device achieves a switch resistance of 2.4±1.4 Ω to 1.8±0.6 Ω at 90-100 V in open laboratory environments (nonpackaged). This design has the potential to replace conventional electromagnetic relays in application areas such as automated testing equipment and high-performance switching networks.
56 citations
TL;DR: In this paper, the design and characterization of compact high-power RF microelectromechanical system single-pole single-throw (SPST) and singlepole four-throw(SP4T) metal-contact switches are presented.
Abstract: This paper presents the design and characterization of compact high-power RF microelectromechanical system single-pole single-throw (SPST) and single-pole four-throw (SP4T) metal-contact switches. The SPST design results in a contact force of 1.9-2.8 mN at 80-90 V distributed over eight contacts and using four independent quadrants for actuation. The SP4T is a derivative of the SPST and results in a contact force of 0.45-0.7 mN per switch at 80-90 V. S-parameter measurements show an up-state capacitance of 70 and 17 fF along with a down-state resistance of 1-2 and 2-4 Ω using Au-to-Ru contacts for the SPST and SP4T switches, respectively. The switch pull-in and release voltages are 50 and 45 V, respectively, and the switching time is t on ~ 10 μs and t off ~ 2 μs. The SPST and SP4T are capable of handling 10 and 2 W up to 100 million cycles, and the SPST has been tested with 30 W of power up to 30 million cycles before failure (all cold switched). The application areas are in compact high-power applications such as wireless communication systems and base-stations.
44 citations
TL;DR: The novel switch architecture employs electrothermal hydraulic microactuators to provide mechanical actuation and 3-D out-of-plane silicon cantilevers that have both spring action and latching mechanisms that facilitates an off-state gap separation distance of 200 mum between ohmic contacts, without the need for any hold power.
Abstract: This paper introduces a new concept in 3-D RF microelectromechanical systems switches intended for power applications. The novel switch architecture employs electrothermal hydraulic microactuators to provide mechanical actuation and 3-D out-of-plane silicon cantilevers that have both spring action and latching mechanisms. This facilitates an off-state gap separation distance of 200 mum between ohmic contacts, without the need for any hold power. Having a simple assembly, many of the inherent problems associated with the more traditional suspension-bridge and cantilever-type-beam architectures can be overcome. A single-pole single-throw switch has been investigated, and its measured on-state insertion and return losses are less than 0.3 dB up to 10 GHz and greater than 15 dB up to 12 GHz, respectively, while the off-state isolation is better than 30 dB up to 12 GHz. The switch works well in both hot- and cold-switching modes, with 4.6 W of RF power at 10 GHz and without any signs of degradation to the ohmic contacts.
35 citations
Cites background from "Parallel-contact metal-contact RF-M..."
...Considering that the RF power-handling capacity varies between architectural designs, there have been a number of diverse approaches to improve the RF power-handling capacity, for example, the addition of an electrode to pull the beam upward [4]–[6] or to toggle the cantilever beam downward [7]; an array of many switching elements, in order to increase isolation and reduce current density [8], [9]; an increase in the width and thickness of the beam [8], [10]; an increase in the contact force [11]–[13]; and the use of extraordinary contact materials, such as a diamond film [14], [15], Pt, or Ir [16]....
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References
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TL;DR: In this paper, the authors describe a microelectromechanical (MEM) relay technology for high-performance reconfigurable RF circuits, which is a metal contact relay with electrical isolation between signal and drive lines.
Abstract: We describe a microelectromechanical (MEM) relay technology for high-performance reconfigurable RF circuits. This microrelay, fabricated using surface micromachining, is a metal contact relay with electrical isolation between signal and drive lines. This relay provides excellent switching performance over a broad frequency band (insertion loss of 0.1 dB and isolation of 30 dB at 40 GHz), versatility in switch circuit configurations (microstrip and coplanar, shunt and series), and the capability for monolithic integration with high-frequency electronics. In addition, this MEM relay technology has demonstrated yields and lifetimes that are promising for RF circuit implementation.
172 citations
08 Jun 2003
TL;DR: An electrostatically actuated broadband ohmic microswitch has been developed that has applications from DC through the microwave region as discussed by the authors, which is a 3-terminal device based on a cantilever beam and is fabricated using an all-metal, surface micromachining process.
Abstract: An electrostatically actuated broadband ohmic microswitch has been developed that has applications from DC through the microwave region. The microswitch is a 3-terminal device based on a cantilever beam and is fabricated using an all-metal, surface micromachining process. It operates in a hermetic environment obtained through a wafer-bonding process. Characteristics of the wafer-level packaged switch include DC on-resistance of less than 1 ohm with an actuation voltage of 80 V, lifetime of greater than 10/sup 10/ cycles with on-resistance variation of less than 0.2 Ohm and current handling capability of 1 A. Key RF characteristics at 2 GHz include an insertion loss of 0.32 dB and isolation of 33 dB for our 4-contact microswitch. Preliminary measurements at higher microwave frequencies are extremely promising with full characterization and planned product improvements underway.
114 citations
25 Jan 1998
TL;DR: In this paper, a new precision measurement technique was developed that enables investigations of electric contacts at contact forces varying continuously in the range from 0.1 mN to more than 10 mN.
Abstract: The design of a microrelay actuator has to be based on the characteristic data of the contact material used. These data were determined experimentally at Au, AuNi5 and Rh switching electric contacts. The samples were cleaned with good result using the "Schaltreinigung" procedure. A new precision measurement technique was developed that enables investigations of electric contacts at contact forces varying continuously in the range from 0.1 mN to more than 10 mN. It was found that AuNi5 and Rh are contact materials well suited for microrelays, whereas Au is not appropriate due to its high adherence. Stable contact and reliable opening are provided by forces altogether as low as 0.6 mN. The experimental data were used successfully in dimensioning the moving wedge actuator used in silicon microrelays.
101 citations
08 Jun 2003
TL;DR: In this article, a fully integrated RF microswitch was proposed based on a combination of thermal actuation and electrostatic latching hold. But the performance of the switch was not evaluated.
Abstract: We have demonstrated the feasibility of a fully integrated RF microswitch. It is based on a combination of thermal actuation and electrostatic latching hold. This method enables to combine the advantages of both actuation modes : the low voltage power supply and high reliability of the thermal actuation, and the low power consumption of the electrostatic latching. An analytical model was developed in order to predict the shape of the beam versus the temperature. An algorithm was also developed in order to evaluate the damping behavior of the switch taking the beam shape deflection into account. A design composed of a 400/spl times/50 /spl mu/m silicon nitride clamped beam was selected. The beam includes titanium nitride heating resistors, and aluminum blocks for bimorph actuation. The RF lines and the contacts are made of a 1 /spl mu/m thick gold layer. The 3 /spl mu/m air gap is fabricated using a polymer sacrificial layer. The driver of the switch, for the thermal actuation and the electrostatic latching, was manufactured in a 0.25 /spl mu/m BiCMOS technology. For each activation, the switch requires a 20 mA current under 2 V during /spl sim/200 /spl mu/s. For the electrostatic hold, the MEMS was designed for less than 10 volts. Due to residual stress in the beam material, a 5 V shift of the hold voltage has been experimentally observed on first prototypes. Reliability of thermal actuation has been tested with more than 10/sup 9/ cycles without any failure or contact degradation. Very interesting RF performances were measured, even with standard wafer (15/spl Omega/.cm) : -57 dB isolation and 0.18 dB insertion loss at 2 GHz.
68 citations
08 Jun 2003
TL;DR: In this article, a steady-state thermal-electrical finite element model of microswitches with gold-gold contacts is presented, which correctly predicts the switch voltage at which the drain trace melts, but underestimates the switch resistance, and therefore overestimates the failure current.
Abstract: Electrostatically actuated microswitches and relays have been developed at Northeastern University and Analog Devices, Inc. Here, we report a steady-state thermal-electrical finite element model of microswitches with gold-gold contacts. The modeling results show that in a microswitch with a typical geometry, the thermal constriction occurs in the thin film trace leading up to the contact, and not at the contact interface. The model correctly predicts the switch voltage at which the drain trace melts, but underestimates the switch resistance, and therefore overestimates the failure current. SEM images indicate that the contact area increases significantly with current.
16 citations