RF MEMS电容式开关结构层释放技术

研究了RF MEMS开关的制造工艺流程和聚酰亚胺牺牲层的去除工艺。在开关的设计和加工中采用在信号线两侧的地线上生长一层绝缘介质层,直流偏置线生成在绝缘介质层之上,与桥的锚点相连接,实现了交直流隔离。讨论了干法刻蚀和湿法刻蚀牺牲层技术。干法刻蚀容易造成绝缘介质层的刻蚀和损伤。采用湿法刻蚀结合临界点干燥技术,可以获得理想的微梁结构。通过测试,开关样品的下拉电压为34 V～40 V,下拉距离为(1.7±0.2)μm,满足设计要求。

Research on Release of Structure Layer for RF MEMS Capacitive Switches

The fabrication process and the removal of polyimide sacrificial layer for RF MEMS capacitive switches are investigated.A Si3N4 dielectric layer was deposited on the grounding wire layer using PECVD technology in this work,and then the DC bias gold line layer was sputtered on the dielectric layer Si3N4,so the isolation of DC and AC has been implemented.The wet and dry etching technology for removing the sacrificial layer has been discussed.The dry etching method induces the Si3N4 dielectric layer etched and damaged slightly.The structure layer has been released successfully by using wet etching combined with the critical point drying technology.The releasing process and parameters have been presented.The test pull-down voltage of RF MEMS capacitive Switch prototype is 30 V～40 V and the pull-down distance is(1.7±0.2)μm,which are in agreement with the design.