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This paper illustrates the design, modeling, and analysis of bridge type structure based capacitive RF MEMS switch with different beam thickness and materials. We have used Ashby's approach to select the best materials in each and every level which helped to improve the overall performance of the switch in terms of mechanical, electrical, and RF properties. Silicon Nitride thin film (ε r = 7.8) is used as a dielectric material. The beam structure stiffness is analyzed with different materials, such as gold, titanium, and platinum, within these materials gold with high thermal conductivity and Euler-Young's modulus of 77 GPa is offering the best performance. Incorporation of meanders and perforations to the membrane helped to reduce the pull-in voltage. The proposed switch is offering very low pull-in voltage of 1.9 V. The deflection of beam thickness is tabulated for the three materials among them the 2 ţm thickness is best beam thickness for the switch for X-band applications. The switch offers best return loss (S 11) of −21.36 dB, insertion loss (S 12) of −0.147 dB, and isolation (S 21) of −52.04 dB at 8GHz. The switch presented in this paper is preferable in X-band applications. INDEX TERMS Fixed-fixed membrane, spring constant, pull-in voltage, switching time, X-band, material science.

Movable suspended microstructures are common features of sensors and devices in the field of micro electro mechanical systems (MEMS). This paper addresses the study of approach to model the capacitance for the crab-type meander-based RF MEMS shunt switch with etching holes on the beam. The presented paper evaluates the parallel-plate capacitance and fringing-field capacitance caused by the etching holes on the beam and introduces empirical formulae. From the literature study, an accurate empirical formula is presented. The capacitance involves a parallel plate and a fringing field. The parallel-plate capacitance term is proposed by the authors of this work; the fringing-field capacitance term is adopted from previous work. The proposed accurate empirical capacitance formulae are derived by curve fitting the simulated values through the commercially available FEM solver. The two existing benchmark models of fringing-field capacitance are used to modify the perforated MEMS switch to obtain the proposed formula. With the existing models and presented formula, the capacitances are computed for a wide range of dimensions; the simulated results of the presented formula are validated with the calculated results. The deviation of the presented formula has an error estimation of ±0.1%. The variation of the capacitance with different deictic thicknesses and errors is estimated and analyzed for the presented formula. The Mejis model is found to be satisfactory for a lower air gap and a 1-µm-thick beam. The Yang's model is sufficient for a higher air gap and a large number of etching holes. The proposed formulae are good for the ligament efficiency µ ≤ 0.5, with thickness >1 µm, and the deviation of error estimation is within ±5%. INDEX TERMS Fixed-fixed beam, etching holes, ligament efficiency, RF MEMS, parallel-plate capacitance, fringing-field capacitance.

In this paper, a capacitive RF MEMS Switch is designed and simulated for different parameter variation like by varying beam thickness and different materials. Materials play an important role on the performance of the device. So it is necessary to select an appropriate material for the beam. Three different materials are taken for the dielectric layer among them Silicon nitrite shown good performance. Similarly three different materials are considered for the beam like gold, titanium, and platinum. From the three materials gold is chosen as the best material for the beam by ASBYS approach. Gold is having high thermal conductivity with young’s modulus 77Gpa.The pull-in voltage of three materials is given as 1.9V, 2.76V, 2.28V. Beam thickness is also impact for the switch, so in this paper variation of beam thickness are shows clearly, by considering different beam thickness like 0.5um to 3um. The variation of beam thickness is tabulated for the three materials among the 2um thickness is best beam thickness for switch to operated X-band applications. The switch exhibits the return loss (S11) of -21.36dB, insertion loss (S12) of -0.147dB, and this switch is having good isolation (S21) of 52.04dB. Finally to designed and simulated fixed-fixed type RF MEMS switch is applicable for low frequency like the X-band applications.