A Novel Radio Frequency(RF)MEMS Switch Based On Silicon Wafer

A RF switch is one of the basic devices in the whole RF communication network. A novel RF MEMS switches has been carried out based on silicon wafer. In this thesis, the principle of design and the structure of RF MEMS switches have also been introduced. At the same time, the approximate mechanical model of devices has been put forward. Based on these, both pull-in voltage and insertion loss have been analyzed and optimized. Later, the fabrication flow has been decided. And lastly the test result has been given out. The details are given as follows:Firstly, in the first chapter, many kinds of RF MEMS devices have been introduced especially RF MEMS switches. Compared with the traditional RF switches, RF MEMS switches have simpler structure, lower insertion loss and higher fabrication toleration, which will benefit reducing cost and increasing productivity. After analysis, the structure driven by static electricity has been adopted.The relationship between the structure of devices and insertion loss has been developed in details. According to that, a novel RF MEMS structure has been brought out, which is the RF transmission line built on a movable membrane. By reducing the thickness of dielectric of the RF transmission line largely, it will benefit to earn low insertion loss. In order to realize thin dielectric structure of the transmission line and combined the principle of the design of CPW, a cavity structure has also been studied.The silicon surface microfabrication process was developed and emphatically introduced several key surface micorfabrication technologies such as how to fill in the sacrificial layer and how to make it smooth. The parameters of the fabrication process have been decided. The switch has been fabricated successfully and the result has been shown as the picture taken by SEM.The RF performance of the switch has been tested by the Microwave network and analyzed. Based on the normal silicon wafer with the resistivity of 4-8cm, the switch is fabricated by surface micromachining technology, with the dimension of 1000 600 300m3 The pull in voltage is about 35V. And in the frequency range of 50MHz to 10GHz, the insertion loss is lower than 2dB and the isolation is better than 40dB.