【作者】 宣云；

【导师】 刘泽文；

【作者基本信息】 清华大学 ， 电子科学与技术， 2005， 硕士

【摘要】 射频微电子机械系统(RF MEMS)技术在现代通信领域中越来越受到重视。开关是射频电路中的重要元件,具有低插入损耗、高隔离度、低开启电压、高可靠性的 RF MEMS 开关已经成为 RF MEMS 器件中的研究热点。RF MEMS 开关可以独立使用,也可以组合成阵列等器件以获得更优的性能或获得不同的功能,这使 RF MEMS 开关的应用范围更加广泛。共面波导传输线是 RF MEMS 开关的承载体,也是将单个开关组合成阵列等器件的关键元件,因此对共面波导传输线的优化设计是 RF MEMS 开关器件设计的第一步。本文设计了四种 RF MEMS 器件,其中包括低损耗的共面波导传输线、具有容性互连点的电容耦合式开关、欧姆接触式开关和分布式加载线移相器。制定了三种各具特色的整体工艺流程,并设计出兼容这三种工艺流程的版图。通过流水实验实现了设计,并对工艺流程中的关键工艺进行了较深入的研究。论文首先总结了共面波导传输线的设计方法,通过分析计算得到了便于使用的共面波导参数设计表。以降低开关的开启电压和谐振点频率为目标对旁路型电容耦合式开关进行了优化设计,获得一种具有容性互连点结构的电容耦合式开关。以工艺兼容性为目标对欧姆接触开关进行了设计,并开发出一种利用种子层作为下电极的准三层金属工艺,可用于实现欧姆接触式开关中的金属触点结构。对分布式加载线移相器的设计方法作了总结,并给出设计实例。论文为所设计的器件制定了三种可行的整体工艺流程,这三种工艺流程各有特点,可根据不同的需要进行选择。设计了能同时兼容三种工艺流程的版图,并进行了流水实验。对种子层图形化、电镀金和聚酰亚胺图形化这三项关键工艺进行了较深入的研究和总结。经过多次流水实验,获得了所设计的器件,并对其进行了测试。实测数据表明,所设计的共面波导插损小于 0.85dB,具有容性互连点的电容耦合式开关的开启电压约 20V,插入损耗为 1.03dB@20GHz,隔离度为 26.5dB@20GHz;分布式移相器开启电压约 65V。为了排除用于测量的 PAD 等结构的影响,设计了一种提取“纯”器件参数的数据处理方法,并应用于共面波导的测试数据处理。更多还原

【Abstract】 RF MEMS technology becomes more and more attractive in the communicationfield nowadays. Switch is one of the most important element in RF circuit, study onRF MEMS switch with low insertion-loss, high isolation, low actuation voltage hasbecome hot topics. RF MEMS switch can be used as an independent component, or aswitch array to achieve better performance or different functions according to itsapplications. Since RF MEMS switch is in general connected and supported bycoplanar-waveguide (CPW), so the optimization of CPW is the first step of RFMEMS switch device design.Four kinds of RF MEMS devices are designed in this thesis, including low lossCPW, capacitive shunt switch with capacitive connection, Ohmic serial switch anddistributed phase shifter. The corresponding process flows and layout is designed, andseveral key processes are investigated in detail. Based on the developed processes,the designed devices are realized and measured.The thesis firstly introduces the design method of CPW;a convenient CPWparameter table is obtained by calculation. An optimized design of capacitiveshunt switch is carried out, which has lower actuation voltage and resonant frequency.An ohmic switch with compatible process is designed. A process to realize metallicdimple with seed layer is established. A distributed phase shifter is designed.Three process flowes are designed for those devices. A set of layout that iscompatible with three process flows is presented. Key process steps are investigated,including seed layer etching, gold electroplating and polyimide patterning.The designed device are obtained and measured. The insertion-loss ofCPW is less than 0.85dB. The actuation voltage of designed capacitive switchis 20V, its insertion-loss is 1.03dB@20GHz, and its isolation is26.5dB@20GHz. The actuation voltage of distributed phase shifter is 65V.In order to trim the effect of pad structure in microwave performancemeasurement, a method to extract the “pure” device data is developed.更多还原