Characteristics of capacitive membrane-type RF MEMS switches

Yeong L. Lai, Yueh Hung Chen

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Developments in microelectromechanical system (MEMS) technology have successfully provided advancement of miniaturization of omnigenous devices and systems such as sensors, transducers, pumps, and motors. The MEMS technology can also be applied to switching of radio-frequency (RF) signals. In this paper, analysis of characteristics of capacitive membrane-type RF MEMS switches, have been developed on the basis of the finite element method. Both the static and modal analyses of the switches are conducted. The characteristics including the displacement, stress, effective stiffness constant, natural frequency, and switching time are studied. The structures of the switches are critical for determination of switch performance. How the characteristics of the capacitive membrane-type RF MEMS switches are affected by the structures of the switches is investigated comprehensively. The three-dimensional structure of a capacitive RF MEMS switch is shown in Fig. 1. The MEMS switch consists of a coplanar waveguide (CPW) transmission line, a silicon nitride dielectric layer, and an aluminum metal membrane. Fig. 2 shows the displacement characteristics of the switches as a function of the connection beam width. The maximum displacement of the switch occurs at the edge of the membrane and increases with the decreasing width of the connection beam. The values of the maximum displacement of the aluminum switches with 20-, 60-, and 100-μm connection beams are 4.39, 2.21, and 1.56 μm, respectively. The characteristics of the maximum displacement, the maximum stress, the effective stiffness constant, and the actuation voltage of the switches with the connection beam widths ranging from 20 to 100 μm are shown in Fig. 3. The dynamic behavior of the RF MEMS switches is an important issue as far as the reliability and stability are concerned. Resonance problems often accompany mechanical systems. When the vibration frequency of the mechanical system reaches the natural frequency of the system structure, the resonance occurs. The resonance easily causes fatigue and destruction of the mechanical systems. Table I summarizes the values of the first-mode natural frequency and the corresponding switching time of the switches. The switches have the natural frequencies ranging from 68.69 to 112.53 kHz. The characteristics of the capacitive membrane-type RF MEMS switches with the different structures have been investigated using the finite element method from both the static and modal perspectives. The comprehensive study of the membrane-type switches is conducted to provide appropriate design for practical high frequency applications.

Original languageEnglish
Title of host publication2005 International Semiconductor Device Research Symposium
Number of pages2
Publication statusPublished - 2005 Dec 1
Event2005 International Semiconductor Device Research Symposium - Bethesda, MD, United States
Duration: 2005 Dec 72005 Dec 9


Other2005 International Semiconductor Device Research Symposium
CountryUnited States
CityBethesda, MD

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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