【作者】 陈光红；

【导师】 于映；

【作者基本信息】 福州大学 ， 微电子学与固体电子学， 2005， 硕士

【摘要】 射频MEMS开关与目前射频系统中所使用的PIN二极管开关和MESFET开关相比,具有更低的插入损耗、更高的隔离度、更好的线性、更低的功耗和可应用频带更宽。利用射频MEMS开关可制作移相器、开关式滤波器、开关阵列等,应用于雷达、卫星通信、无线通信等系统中。本课题主要研究接触式射频MEMS开关的制作工艺及其直流特性。对接触式射频MEMS开关的电极、波导、触点、牺牲层、悬梁的制作工艺进行了研究,制作出射频MEMS开关样品,对开关的直流特性进行了测试和研究。研究金属的淀积和剥离工艺,解决了厚金的剥离问题,制作出金的厚度为2μm,信号线与地线之间的间距为8μm的波导;研究PECVD法生长氮化硅工艺,在牺牲层聚酰亚胺上生长出厚度为1μm的氮化硅,解决了在聚酰亚胺上生长氮化硅薄膜破裂的问题;研究ICP刻蚀氮化硅和等离子体刻蚀聚酰亚胺的工艺,成功地制作出悬梁,解决了释放牺牲层出现粘连的问题。本文用共聚焦显微镜测试氮化硅薄膜悬梁悬起的高度,确定出最适合接触式射频MEMS开关中使用的氮化硅生长工艺条件。用手动探针台测试接触式射频MEMS开关的通断特性,用显微镜测试开关的驱动特性,确定出开关的阈值电压为22-27V。用共聚焦显微镜测试开关加直流电压后的下拉高度,研究开关的悬梁在驱动电压下的弯曲程度及下降达到的最低位置。本文制作出的开关由于悬梁中存在残余应力,开关在加直流电压后触点不能下降到所需的高度与下电极接触,尚未实现开关的“导通”。更多还原

【Abstract】 RF MEMS switches have an advantage over PIN diodes and MESFETs in isolation, insertion loss, linearity, power dissipation and can be used in broader frequency band. RF MEMS switches can be used to make phase shifter, filter, switch array, etc. The main application areas of MEMS switches are radar systems, satellite communication systems and wireless communication systems. The fabrication processes of metal-metal contact RF MEMS switch and the test of its DC property are the main content of this thesis.Metal-metal contact switch includes electrode, waveguide, contact,sacrificial layer and suspended beam.We study the fabrication processes and optimize the process parameters and succeed in making the switch. We test the pull-down voltage of the switch and its height change between down and up state. The fabrication processes of metal-metal contact switch include the following steps. Electrode, waveguide and contact are made through lift-off process. Sacrificial layer is made through rotational spread. The structure of suspended beam is made through PECVD process. The moving parts are released by selectively etching an underlying sacrificial layer through ICP dry etching and oxygen plasma etching.We succeed in depositing and lifting-off gold of 2 micrometer in thickness, plasma enhanced vapor depositing silicon nitride on polymide of 1 micrometer in thickness and releasing the suspended beam. We test the height of silicon nitride suspended beam from different depositing condition in laser-scanning microscope and decide the most proper depositing condition for RF MEMS switch.we research the on and off state of the switch, observe the pull-down property of the assembled sample in microscope and test its pull-down height when applied DC voltage. The pull-down voltage of the switch is from 22 volt to 27volt. The metal contact cannot touch the down electrode when the switch is applied DC voltage due to the residual stress in the thin film, so the signal cannot transmit.更多还原