Material selection methodology for radio frequency (RF) microelectromechanical (MEMS) capacitive shunt switch

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TECHNICAL PAPER

Material selection methodology for radio frequency (RF) microelectromechanical (MEMS) capacitive shunt switch Navneet Gupta1 • R. Ashwin1 Received: 11 July 2017 / Accepted: 25 January 2018 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2018

Abstract This paper describes the process of selecting the most optimum Radio Frequency Micro- electro- mechanical-systems (RFMEMS) switch design using Ashby’s methodology. The switches are compared on the basis of parameters like actuation voltage, insertion loss, isolation and switching time using material selection charts. The chart shows that a low-voltage metal-to-metal contact shunt capacitive RF-MEMS having a bridge structure with Si-GaAs substrate, electroplated gold contacts and silicon nitride dielectric layer, is the most optimum of all the switches considered.

1 Introduction For developing an efficient wireless communication system, complete integration of circuits and radio-frequency (RF) components is necessary. This can be done by using existing semiconductor technology with microelectromechanical systems (MEMS) (Chu et al. 2007). MEMS technology can be defined as miniaturized mechanical and electro-mechanical elements that are made using the microfabrication techniques. This hybrid technique has made an explosive growth in radio frequency (RF), microwave and millimetre-wave applications. RF-MEMS switches are the prime candidate in RF and microwave communication systems. The operation of a RF-MEMS switch will use the mechanical movement based on a control signal. In many applications, RF-MEMS switch is widely used in handheld communication device such as GSM mobile phones (Jaaffar et al. 2011). The advantage of MEMS switches over their solid state counterparts is their extremely low series resistance, low resistive loss, negligible power consumption, good isolation and high RF power handling capabilities (Balaraman et al. 2002; Goldsmith et al. 1995; Jensen et al. 2003; Sharma and Gupta 2014). In addition, since MEMS switches do not contain a semiconductor junction, they & Navneet Gupta [email protected] 1

Department of Electrical and Electronics Engineering, Birla Institute of Technology and Science, Pilani Campus, Pilani, Rajasthan 333031, India

exhibit negligible intermodulation distortion (Pacheco et al. 2000). Detailed comparisons between these switches are given in Table 1. From the fabrication point of view, the main drawback of conventional electromechanical switches is the impossibility of batch production. By adopting the highly repeatable nanofabrication techniques for MEMS, they can be easily reproduced and integrated with the existing silicon technology. (Chan et al. 2003). There are mainly two types of RF-MEMS switches: bridge type (fixed–fixed) and cantilever (one-end fixed) beam type (Leng and Rebeiz 2001; Liu 2010; Muldavin and Rebeiz 2001; Sharma and Gupta 2015; Varadan et al. 2002). Since the switches are characterized by various parameters, it is difficult t