Design of compact, high capacitance ratio MEMS switch for X - Band applications using high-k dielectric materials

The paper discusses the design aspects of capacitive RF MEMS Symmetric Toggle Switch (STS) with particular emphasis on device compactness, reliability, and improvement in isolation & insertion loss by incorporating hafnium dioxide (HfO2) as a dielectric material. The major impact of the change from SiO2 to HfO2 having dielectric constant of 20, is the reduction in overall dimensions of the switch; capacitive overlap area is reduced by 75% leading to overall reduction of about 50%. Significant improvement in isolation (-43dB) and insertion loss (-0.014dB), at 11 GHz with 50 nm thick HfO2 as a dielectric layer compared to -29 dB and -0.016 dB @ 11 GHz respectively for SiO2 makes hafnium dioxide an attractive dielectric for RF micro-electro-mechanical systems (MEMS) switch for new generation of low-loss high-linearity microwave circuits.