薄膜体声波谐振器性能模型参数的提取方法

Method for extracting parameters of performance model of thin film bulk acoustic wave resonator

薄膜体声波谐振器(FBAR)性能模型包含两个关系式:一个是FBAR有效机电耦合系数与其形状因子(面积与周长之比)的关系式,另一个是FBAR品质因数与其形状因子的关系式。前一个关系式中的参数为FBAR边缘区域的等效宽度,后一个关系式中的参数为表征FBAR横向声能泄漏的因子。为使性能模型用于不同膜层结构、材料及制备工艺的FBAR,建立FBAR性能模型参数的提取流程。以一种5层复合结构的FBAR为例,在同一晶片上,制备多个不同形状因子的FBAR。针对其中一个五边形FBAR,在ADS软件中通过Mason电路模型仿真得到其性能值(有效机电耦合系数和品质因数);再使用矢量网络分析仪和射频探针台实测其性能值。将仿真与实测得到的性能值代入FBAR性能模型,解算出这两个参数。确定参数之后,使用FBAR性能模型预测同一晶片上其它不同性能因子FBAR的有效机电耦合系数和品质因数,预测值的相对误差在3%之内,验证了该参数提取流程的有效性。

The thin film bulk acoustic resonator （FBAR） performance model contains two relationships： one is the relation-ship between the effective electromechanical coupling coefficient and the shape factor （ratio of area and perimeter） of FBAR, theother is the relationship between the quality factor and the shape factor. The parameter in the former is the equivalent width of re-gion at the edge of FBAR. The parameter in the latter is the transmission coefficient of lateral acoustic energy in FBAR. In orderto make the FBAR performance model be applied for different film structure, materials and process technology of FBAR, a newprocedure for extracting the parameters of FBAR performance model was proposed. In the case of 5 layers composite structureFBAR, several FBARs with the same film structure and different shape factor were fabricated on the same wafer. According toone of the FBARs, the effective electromechanical coupling coefficient and the quality factor were simulated by Mason circuit mod-el and measured by vector network analyzer and RF probe station. The two parameters in FBAR performance model were solvedby taking these values into the two relationships. After determining the parameters, the FBAR performance model was used topredict the effective electromechanical coupling coefficient and the quality factor of other FBARs on wafer. Compared to measuredvalue, the relative error of prediction values is within 3 %, which verifies the validity of the procedure for extracting parameters.