RF MEMS Metal-Contact Switches With mN-Contact and Restoring Forces and Low Process Sensitivity
06 Jan 2011-IEEE Transactions on Microwave Theory and Techniques (IEEE)-Vol. 59, Iss: 5, pp 1230-1237
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.
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TL;DR: In this paper, the authors defined the ideal switch as a device having virtually no insertion loss (Ron = 0 Ω) over a wide frequency range, very high isolation [off-state capacitance (Coff)] = 0 fF), extremely high linearity (IIP2 and IIP3 → infinite), medium-to high-power handling (100 mW to 1 kW), and no dc power consumption.
Abstract: The RF community has long been searching for the ideal switch since the birth of electronics, and it is defined as a device having virtually no insertion loss (Ron = 0 Ω) over a wide frequency range, very high isolation [off-state capacitance (Coff)] = 0 fF), extremely high linearity (IIP2 and IIP3 → infinite), medium- to high-power handling (100 mW to 1 kW), and no dc power consumption. Our entire RF infrastructure ecosystem, from communication system networks, to satellite systems, to wideband spectral analysis, to instrumentation and radar systems, uses a variety of switches for signal routing and control (attenuation, phase shifting, etc.). The ideal switch was achieved long time ago using electromechanical relays, and even after nearly 100 years, it is still the best RF switch ever made from an electrical perspective [1]. It has very low insertion loss (Ron <;1 Ω), very high isolation (Coff of few fF), very high linearity and high power handling (100 mW to 50 W). However, it is bulky, expensive, and has an average lifetime of few million cycles.
118 citations
Cites background from "RF MEMS Metal-Contact Switches With..."
...Most of the work concentrated on electrostatic actuators [32]–[34], and some effort was placed on piezoelectric designs [35]....
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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
Cites background from "RF MEMS Metal-Contact Switches With..."
...The mechanical response of the switch with area, , and initial gap, , due to an applied voltage, , and modeled as a single-degree-offreedom system is given by [2] (9) (10) where is the spring constant under actuation conditions (6000 N/m) and is the effective switching mass (6.25 g), determined…...
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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 "RF MEMS Metal-Contact Switches With..."
...Also, virtually no hysteresis is observed when the temperature is cycled back down to 25 ◦C [4]....
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...single-crystal silicon actuators, while the UCSD switches use tethers and other stress-stable designs [4], [5]....
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...The development of RF MEMS metal contact switches has taken the path of large actuators with high contact and release forces, such as the Omron switch [3], the UCSD switches [4]– [6], the RFMD switch [7], and the Radant MEMS switch [2]....
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01 Feb 2014-Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems
TL;DR: In this article, a novel torsional RF MEMS capacitive switch design on silicon substrate is presented, which optimized switch topology such as reduction in up-state capacitance results in insertion loss better than 0.1 dB till 20 GHz.
Abstract: A novel torsional RF MEMS capacitive switch design on silicon substrate is presented. The optimized switch topology such as reduction in up-state capacitance results in insertion loss better than ź0.1 dB till 20 GHz. Off to on state capacitance ratio is also improved by 18 fold and isolation is better than ź43 dB at 9.5 GHz. The achieved on state return loss is ź38 dB as compared to ź21 dB at 9.5 GHz. An optimized reduction in contact area and use of floating metal layer increases the switching speed from 56 to 46 μsec. It also increases the switch reliability by alleviating the stiction.
56 citations
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
TL;DR: In this paper, the mean cycles-to-failure measured on an ensemble of switches was 430 billion switch cycles and the longest lifetime exhibited without degradation of the switch was 914 billion cycles.
Abstract: Radio frequency microelectromechanical systems (RF MEMS) cantilever contact switches have been tested for lifetime. The mean cycles-to-failure measured on an ensemble of switches was 430 billion switch cycles. The longest lifetime exhibited without degradation of the switch was 914 billion switch cycles. The devices were switched at 20 kHz with an incident RF frequency of 10 GHz and an incident RF power of 20 dBm. Testing was performed continuously over a period of approximately 18 months. The switches were operated in a cold-switched mode.
105 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
TL;DR: In this article, surface micromachined microswitches and microrelays that are based on electroplated materials are described. But their lifetime is limited to 107 cycles cold switched at current levels exceeding 10 ma.
Abstract: In this paper, we discuss our work on surface micromachined microswitches and microrelays that are based on electroplated materials. We have successfully fabricated devices with lifetimes exceeding 107 cycles cold switched at current levels exceeding 10 ma. Contact resistance is consistently below one ohm for a single contact. Multiple contact devices have much lower effective contact resistance. ©1999 John Wiley & Sons, Inc. Int J RF and Microwave CAE 9: 338–347, 1999.
98 citations