超薄硅衬底氮化铝Lamb波压电谐振器

摘要

针对Lamb波压电声波传感器高品质因数(Q值)、低检测极限(LOD)和易集成的性能要求,本文基于SOI(Silicon-on-insulator)硅片,通过底层硅(Handling layer)干法刻蚀和中间层(Boxing layer)自截止的方法实现2 μm超薄均一的硅衬底结构,然后沉积2 μm厚具备高C轴择优取向的氮化铝(AlN)压电薄膜.传感器薄膜区域外设置双端增强反射栅结构用于提高 Q值,从而有效降低器件的检测极限,并通过微量水分测试验证性能.该谐振器零阶反对称模式(A0)和零阶对称模式(S0)的谐振状态的实测结果和COMSOL二维模型仿真结果一致,所制作的Lamb波谐振器A0模式的主峰Q值为703,S0模式的主峰 Q值为403.微量水分测试S0模式的检测极限优于A0模式,最低检测极限值为0.06% RH.结果表明,氮化铝超薄硅衬底Lamb波压电谐振器能够实现微量水分等高精度检测.%In order to achieve the performance requirements of piezoelectric acoustic Lame wave sensor with high quality factor(Q factor),low limit of detection(LOD)and easy integration,a method was presented in the paper.First,an ultrathin and uniform 2 μm-thick silicon substrate was obtained by dry etching of handling silicon layer and automatic stopping of boxing layer based on SOI(Silicon-on-insulator)wafer,and then a 2 μm-thick Aluminum Nitride(AlN)piezoelectric thin film with high C axis oriented was deposited.High Q factor could be obtained by the double end reflectors outside the membrane.T he LOD could be effectively reduced by using the resonator,and could be verified by the application of trace moisture detection.The experimental results of the lowest anti-symmetric mode (A0)and symmetric mode(S0)were consistent with the simulation results obtained by using software CMOSOL.The prominent peak value of Q factor of the resonator for A0mode was 703,and S0was 403.The limit of detection of S0mode was better than that of A0mode,whose LOD was 0.06% RH. It can be concluded that Lamb wave resonator designed in the paper can be utilized as the high preci-sion detection such as trace moisture detection.