Very low complexity RF-MEMS technology for wide range tunable microwave filters

Siegel, C.; Ziegler, Volker; Prechtel, U.; Schonlinner, B.; Schumacher, Hermann

doi:10.1109/eumc.2005.1608937

Cited by 18 publications

(9 citation statements)

References 2 publications

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“…Controlling the residual stress and achieving temperature compensation in these structures are very difficult due to the diverse material properties. Significant process optimization is necessary and the resulting residual stress and temperature compensation are very sensitive to process parameter variations [43,44,46].…”

Section: Introductionmentioning

confidence: 99%

Microwave MEMS devices designed for process robustness and operational reliability

Sterner

Somjit

Shah

et al. 2011

Int. J. Microw. Wireless Technol.

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, antti ra ¤isa ¤nen 2 and joachim oberhammer 1 This paper presents an overview on novel microwave micro-electromechanical systems (MEMS) device concepts developed in our research group during the last 5 years, which are specifically designed for addressing some fundamental problems for reliable device operation and robustness to process parameter variation. In contrast to conventional solutions, the presented device concepts are targeted at eliminating their respective failure modes rather than reducing or controlling them. Novel concepts of MEMS phase shifters, tunable microwave surfaces, reconfigurable leaky-wave antennas, multi-stable switches, and tunable capacitors are presented, featuring the following innovative design elements: dielectric-less actuators to overcome dielectric charging; reversing active/passive functions in MEMS switch actuators to improve recovery from contact stiction; symmetrical anti-parallel metallization for full stress-control and temperature compensation of composite dielectric/metal layers for free-standing structures; monocrystalline silicon as structural material for superior mechanical performance; and eliminating thin metallic bridges for high-power handling. This paper summarizes the design, fabrication, and measurement of devices featuring these concepts, enhanced by new characterization data, and discusses them in the context of the conventional MEMS device design.Keywords: RF MEMS, Reliability, MEMS design, Phase shifter, Tuneable capacitor, MEMS switch [12]. In general, RF MEMS devices are characterized by near-ideal signal handling performance in terms of insertion loss, isolation, linearity, large tuning range, and by keeping these performance parameters over a very large bandwidth [4,13]. I . I N T R O D U C T I O NMicrowave MEMS are RF MEMS devices that operate with signal frequencies above 30 GHz. With applications moving to higher frequencies, the performance advantages of MEMS devices over their competitors are getting larger. Also, at frequencies where the signal wavelengths are getting closer to the device dimensions, it is possible to miniaturize a complete RF system on a chip, and different ways of interaction between the microwave signals and the micromechanics lead to new possibilities of RF MEMS devices [47].Operational reliability, i.e. the ability of devices to work as specified over the whole lifetime, and robustness to process parameter variations, are key issues in RF MEMS design [14,48].Conventional RF MEMS designs are still characterized by some fundamental problems. Thin metallic bridges, for instance, found in many RF MEMS devices, such as switches and phase shifters, are susceptible to temperature-accelerated creep and fatigue, limiting the device life-time [14]. In contrast, monocrystalline silicon is a very robust MEMS structural material that is at the same time also suitable as RF dielectric material if high-resistivity silicon (HRS) is used [15,49].

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Section: Introductionmentioning

confidence: 99%

Microwave MEMS devices designed for process robustness and operational reliability

Sterner

Somjit

Shah

et al. 2011

Int. J. Microw. Wireless Technol.

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“…At last, the breakdown voltage of nearly lV/nm oxide is excellent. A further improvement compared to the technology that was shown previously [2][3][4][5] is that for reaching the desired stress gradient in the metal layer, two aluminum alloys are used instead of a bimorph layer structure consisting of pure aluminum with silicon on top. Alloys are more stable than pure aluminum concerning creep [8] and both alloys have nearly the same thermal expansion coefficient.…”

Section: Comparison Of Switch Technologiesmentioning

confidence: 95%

“…1. The fabrication starts with the thermal oxidation (1) of a high resistivity silicon substrate (2). The oxide is used as dielectric layer for the capacitive coupling in the RF-path and as an isolation layer for the electrostatic actuation.…”

Section: Technology Description and Its Benefitsmentioning

confidence: 99%

“…Its topology and low-complexity fabrication process with only three photolithographic steps have additionally the potential of low fabrication costs and high reliability. Furthermore, by making use of the same technology, even without the need of implantation regions, switchable filters [2] phase shifters [3] and frequency agile antennas [4] can be realized and easily be integrated. In the following chapters, the simplified fabrication process is explained and the resulting RF-MEMS devices are favorably compared to the former RF-MEMS switch technology [5] in terms of its temperature and RF-behavior.…”

Section: Introductionmentioning

confidence: 99%

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Simplified RF-MEMS Switches Using Implanted Conductors and Thermal Oxide

Siegel¹,

Ziegler²,

Schonlinner³

et al. 2006

2006 European Microwave Conference

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This paper presents microwave capacitive RF-MEMS switches based on a novel simplified fabrication process. The devices are fabricated on a silicon substrate using only one metallisation layer. For the capacitive coupling of the switch, an implanted conductive region and thermally grown silicon oxide is used instead of a second metal layer and an additional dielectric layer. In addition, the formerly used bimorph metallisation layer is replaced by a single-metallisation concept, which results in an increased temperature range of operation. The simplified process as well as the switch topology used lead to high performance and highly reliable RF-MEMS switches.RF-measurement results are presented of Ku-and K-band series switches and a Ka-band parallel switch with low insertion losses between -0.2dB and -0.3dB and isolation of e.g. -17dB at 30GHz.

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“…Thus, tunable bandpass filters constitute an interesting solution to this problem since they can perform over all operating bands. For planar filters, the frequency tunability can be achieved by using various technologies like MEMS [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], ferromagnetic [16], ferroelectric [17][18][19], optical [20], piezoelectric [21,22], mechanical [23], or semiconductor [23][24][25][26][27][28][29][30][31][32] tuning elements.…”

Section: Introductionmentioning

confidence: 99%

Novel factor of merit for center‐frequency tunable bandpass filters comparison

Pistono

Kaddour

Duvillaret

et al. 2009

Micro & Optical Tech Letters

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fifth harmonic signal is also suppressed and suppressed level at the fifth harmonic of 10 GHz is 30 dB. The measurements show similar fundamental responses while the proposed hybrid achieves a suppression improvement of 22 dB at the third harmonic frequency and 27 dB at the fifth harmonic frequency. The sizes of the conventional and second proposed hybrids are commeasurable. The phase difference between Port 2 and Port 3 is 88.8°at fundamental frequency. CONCLUSIONSTwo improved quadrature hybrids with the harmonic suppression are proposed. In comparison to the conventional quadrature hybrid, the proposed quadrature hybrid with the third harmonic suppression achieves not only a 29.5% size reduction but also a 18-dB suppression at the third harmonic frequency, and the other proposed quadrature hybrid achieves a 23-dB suppression at the third harmonic frequency and a 30-dB suppression at the fifth harmonic frequency. The proposed hybrids do not need lumped elements or via-hole grounding, which leads to low cost, simple fabrication process, and excellent design accuracy. ACKNOWLEDGMENTS

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Very low complexity RF-MEMS technology for wide range tunable microwave filters

Cited by 18 publications

References 2 publications

Microwave MEMS devices designed for process robustness and operational reliability

Microwave MEMS devices designed for process robustness and operational reliability

Simplified RF-MEMS Switches Using Implanted Conductors and Thermal Oxide

Novel factor of merit for center‐frequency tunable bandpass filters comparison

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