RF-MEMS capacitive switch with isolation valley at lower frequency band

Micro-fabricated RF-MEMS shunt switches on microwave printed circuit boards (PCB) with high dielectric materials are presented. The copper oxide is used as the switch's dielectric layer. The use of copper oxide has a couple of advantages. Firstly, the high dielectric constant of copper oxide (ε_rη18.1) provides higher down state capacitance, which can re-position the isolation valley at the lower frequency band. Secondly, the fabrication steps to grow copper oxide layer becomes relatively straightforward as opposed to the deposition of silicon nitride. To improve the switching performance by achieving a desirable high capacitance ratio, the down state capacitance must be as high as possible. The down state capacitance and capacitance ratio of copper oxide is found to be higher than with silicon nitride for the same size of overlapping area, between membrane and bottom electrode. A switch with copper oxide is shown to have a lower isolation valley frequency as opposed to that with a silicon nitride layer.