布喇格反射型宽带单晶薄膜体声波滤波器

Preparation and Characterization of Bragg Reflective Wide-band Thin Film Bulk Acoustic Filters

该文研究了一种新型布喇格反射型薄膜体声波(BAW)滤波器的设计方法与制备技术。BAW器件选择机电耦合系数较大的Y43°-铌酸锂(Y43°-LN)单晶薄膜作为压电层材料,并以苯并环丁烯(BCB)作为晶圆键合层,采用离子注入剥离法将亚微米厚度的Y43°-LN单晶薄膜转移至具有布喇格反射层的衬底。BCB既作为键合层,也作为布喇格反射层的第一低声阻抗层,实现了单晶BAW滤波器的制备。设计并制备了三阶BAW滤波器,中心频率为2.93 GHz,绝对带宽和分数带宽分别为247 MHz和8.4%。结果表明,采用薄膜转移技术制备的高机电耦合系数LN单晶薄膜能够实现大带宽BAW滤波器的制备。

The design and fabrication of a novel Bragg reflection-type thin film bulk acoustic wave(BAW)filter is investigated in this work.In BAW devices,Y43°lithium niobate single crystal thin film(Y43°-LN)with high electromechanical coupling coefficient was selected as the piezoelectric material and the Benzocyclobutene(BCB)was used as wafer bonding layer.The Y43°-LN monocrystalline thin film with submicron thickness was transferred to the substrate with Bragg reflection layer by the crystal-ion-slicing method.As both the bonding layer and the first low impedance layer of Bragg reflector,BCB is used to prepare the single crystal BAW filter.The third-order BAW filter wwith the central frequency of 2.93 GHz,absolute bandwidth and fractional bandwidth of 247 MHz and 8.4%respectively is designed and fabricated.The results indicate that the high electromechanical coupling coefficient LN single crystal thin film prepared by film transfer technology can realize the preparation of large-bandwidth BAW filter.