电磁驱动推拉式射频MEMS开关的设计与制作

Design and Fabrication of Electromagnetic Push-Pull RF MEMS Switches

提出了一种新型电磁驱动推拉式射频MEMS开关。针对传统静电驱动单臂梁开关所需驱动电压大、恢复力不足等问题,设计了一种推拉式开关结构,降低了驱动电压(电流),提高了开关的隔离度,同时实现了单刀双掷的功能。单晶Si梁由于自身无应力,解决了悬臂梁残余应力引起的梁变形问题。通过理论计算和有限元分析,优化了开关设计尺寸,在外围永磁铁磁感应梯度dB/dz=100T/m,在线圈通入100mA电流的驱动下,单晶Si扭转梁末端可以获得约10μm的弯曲量,满足开关驱动要求。给出了开关的详细微细加工流程,对开关的传输参数进行了测试,在10GHz时隔离度为-40dB.

A novel electromagnetic push-pull RF MEMS switch was proposed. In order to solve the problems caused by traditional electrostatic cantilever RF MEMS switches, such as high actuation voltage and low recovery force, a new push-pull structure was designed to reduce the actuation voltage （current） and increase the isolation. The designed RF MEMS switch realized the SPDT function. The beam distortion induced by the residual stresses in the cantilever beam was solved due to the single crystalline silicon beam without stress. The dimension of the switch was designed based on theoretical analysis and Finite Element Analysis （FEA）. 10 μm displacement at the free end of the single crystalline silicon beam was obtained at dB/dz = 100 T/m mag- netic-induction gradient of the outside permanent magnet and 100 mA actuation current, satisfying the requirement of switch driving..The microfabrication processes of the designed switches were given. The test of S-parameters shows that the isolation is -40 dB at 10 GHz.