Electromagnetic MEMS RF Switch

This thesis describes the design, fabrication and test of an electromagne~ically actuated RF MEMS switch. The actuator was fabricated using two different wafers. The first is steel where the coil is been made with a soft magnetic material forming an inner and an outer pole. On the saine wafer the transmission line and'the beam support are present. Silicon has been used as the second wafer to fabricate the mover. The mover consists of the same soft magnetic material as used for the pot core. The switch contact along with the soft magnet is held by a fixed-fixed SU-8 beam. The mover is finally been released from the silicon wafer and dropped on the actuator using the traditio!1al flip chip method. SU-8 which is a negative tone photoresist has been extensively used in this project. .,- Firstly by using standard lithography methods, it has been patterned to form a mould for the coil. Secondly it provides a dielectric as the transmission line is fabricated on top of it. Then it has been used as a mixture with particles of Iron (Fe) and Nickel (Ni). This soft magnetic composite is used for the inner and outer poles of the pot core and also as the magnet that sits on top of the coilto form the mover. Finally SU-8 forms the fixed-fixed beam and its support underneath. In this work there are a number of combinations presented as far as the device is· concerned. There are 28 ~witches accommodated on a 2 inch wafer. The footprint of each .device is 5x4 mm2 mainly due to the beam length. Microstrip and cpw MEMS switches have been fabricated with the latter using both a series and a shunt configuration. The isolation using a 100 J.1m break between the signal lines was measured to be 44.7 dB although the simulated model estimated 54 dBs at 10 GHz. The insertion loss for a cpw series switch was measured to be 0.38 dB at the same frequency. The switching on and off time of the device was measured to be 7 ms and 1 J.1S respectively. The coil requires a 1.2 A current to actuate the mover from a 50 J.1m distance.EThOS - Electronic Theses Online ServiceGBUnited Kingdo