Research On Key Technology Of Design And Processing Of High Reliability RF MEMS Single Pole Double Throw Switch

The RF switch is an important part of the microwave control circuit.Because of its low power consumption,small size and good linearity,the RF MEMS switch makes it a research hotspot in the field of MEMS today.Single pole double throw switch(SPDT)is one of RF MEMS switches,which can be widely used in microwave communication systems.This paper presents a single-pole double-throw switch based on a funnel-shaped power divider,and studies the key technologies in its structural design and process,aiming to obtain a high-reliability single-pole double-throw switch.The thesis firstly designed and optimized the structure of SPDT.SPDT is mainly composed of a power splitter and a single-pole single-throw switch.First,the structure is optimized by HFSS software on the basis of the traditional T-junction power splitter.Three types of funnel,trumpet and semicircle are obtained.Power divider,and choose the funnel-shaped power divider with the best performance to be used in SPDT,reduce the insertion loss of SPDT and improve its RF performance.Later,in order to improve the reliability of SPDT,a single-pole single-throw switch with high reliability,high isolation and high resilience was designed for the problem that the contact points of metal contact MEMS switches are easy to stick and cause the switch to fail,which improves the reliability of SPDT.The thesis studies the processing technology of SPDT,introduces the layout design,process flow and important process parameters of SPDT in detail,and focuses on the key processes such as electroplating process,sacrificial layer process and bump passivation to improve the reliability of the switch.In particular,the research on the sacrificial layer process was emphasized.First,the preparation of high-quality polyimide sacrificial layer was studied.Later,in order to overcome the problem of poor step coverage of the polyimide sacrificial layer,the flatness of the sacrificial layer was further improved,and a double layer was developed.Layer sacrificial layer technology.SPDT successfully obtained SPDT samples,and the yield rate reached more than 70%.At the end of the thesis,the SPDT test method and test results are provided,and the mechanical and electrical properties of SPDT are tested respectively.Among them,the mechanical performance test includes driving voltage test,switching time test and life test,and the electrical performance test includes SDPT insertion loss and isolation test.The test results show that the driving voltage of SPDT is 52V,the pull-down time and recovery time of the switch are 47?s and 8?s,respectively,and the life span is?10~7 times.In the frequency range of DC-18GHz,the insertion loss is better than-1.6dB,and the isolation is better than-18dB.