桥式射频MEMS开关上电极薄膜的残余应力改进模型

Improved Model of Residual Stress on Top Electrode Membrane of Fixed-Fixed Beam RF MEMS Switches

桥式射频(RF)微机电系统(MEMS)开关的上电极薄膜残余应力影响开关的响应时间、下拉电压等性能参数,降低了开关的可靠性.在分析传统拉伸线模型的基础上,提出了一种改进的残余应力静力学模型,将残余应力扩展到压应力的情况,并可应用于非对称均布载荷.选取了一组典型的开关参数,计算了双轴残余应力对两端固支MEMS薄膜均布载荷下拉挠度的影响.结果表明,在选取的参数条件下,拉应力增大到1 MPa时,薄膜的最大挠度减少7.95%,压应力增大到-1 MPa时,薄膜的最大挠度增加9.47%,与传统模型的计算结果相比,改进模型消除了非线性叠加产生的约0.3%的误差.采用迭代方法计算下拉电压,对两组实验测试数据与模型计算结果进行了验证,模型计算结果与实验数据基本相符.

Residual stress on the top electrode membrane of fixed-fixed beam radio frequency（RF） micro electro mechanical system（MEMS） switches has impact on the performance of the parameters,such as the response time and the pull-down voltage,and reduces the reliability of RF MEMS switches.On the basis of analysis of the traditional stretched wire model,an improved residual stress model that can be used for compressive stress and in asymmetric situation was proposed in this paper.A group of typical parameters of MEMS switches was selected to simulate and calculate the influence of biaxial residual stress on the deflection of fixed-fixed MEMS membrane.Results show that the maximum deflection reduced by 7.95% under 1 MPa tensile stress,and increased by 9.47% under-1 MPa compressive stress.Compared with the traditional model,the proposed model has eliminated the error resulting from nonlinear superposition by about 0.3%.An experimental verification was taken by using two groups of experimental data to calculate the pull-down voltage.The theoretical results of the model were approximately consistent with the experimental data.