低损耗微波MEMS共平面波导在低阻硅上的实现

Low Loss Microwave MEMS Coplanar Waveguides on Low-Res istivity Silicon

在低阻硅衬底上采用常规CMOS工艺和后处理微机械加工技术实现了微波MEMS共平面波导 ,并与高阻硅基平面结构共平面波导特性进行了比较 .采用混合相似剖分有限元方法设计了一组不同特性阻抗值的传输线 ,并通过关键的混合腐蚀技术制备了 50Ω和 1 2 0Ω两种特性阻抗的传输线 .由于腐蚀去除了信号线下方导致损耗的低阻硅衬底 ,使得传输线插入损耗、散射特性等得以改善 .实验中 ,使用矢量网络分析仪分别在微机械加工前后对传输线进行了 1GHz到 40GHz频段的参数测试 ,利用多线分析技术对测试结果进行了分析 .结果表明在微结构悬浮后共平面波导的损耗特性有了大幅度的降低 ,30GHz处插入损耗约为 7dB/cm ,较腐蚀前降低了 1 0dB/cm .

Microwave transmission lines are designed and fa bricated by the CMOS technology on Si substrates with low and high resistivities.First,the characteristic impedance of the microwave coplanar waveguides (CPW) is analyzed with a new similarity method in FEM.The characteristic impedance of MEMS waveguide is calculated and the change with its different dimens ions is analyzed.Then the samples with characteristic impedances of 120Ω and 50 Ω are fabricated through the micromachining.Measurements are performed at frequencies from 1 to 40GHz.The insert loss of transmission-line shows a great improvement after the structures are suspended.At 30GHz,the insert loss is about 7dB/cm,reduces by mo re than 10dB/cm compared with that of the structures without suspended.