适用于FBAR的ZnO薄膜制备及压电特性分析

采用射频磁控溅射法在Al电极层上制备了适用于 薄膜体声波谐振器(FBAR)的ZnO薄膜, 研究了溅射功率对ZnO薄膜择优取向、压电响应和极化分布的影响。X射线衍射(XRD)测试结 果 表明,在一定范围内,随着溅射功率的增大,ZnO薄膜的择优取向和结晶质量得到提高；但 溅射功率过大,ZnO薄膜的择优取向变差。压电响应力显微镜(PFM)测量表明,溅射功率对薄 膜的压电性能和极化取向也有很大影响, 在所制备的薄膜中,多数晶粒的自发极化方向均垂直向上,表明所制备ZnO薄膜的表面主要 为O 截止；压电响应的振幅与薄膜的结晶质量和择优取向相关,在溅射功率为150W条件下制备的ZnO 在垂直于表面方向上表现出最大压电响应振幅,同时薄膜极化取向分布的一致性最好。

Preparation and piezoelectric properties analysis of ZnO films for film bulk aco ustic resonator

ZnO films used in film bulk acoustic resonator (FBAR) were deposited o n the aluminum bottom electrode layers by radio frequency magnetron sputtering,and how the spu ttering power influences the preferred orientation,piezoelectric response and polarity distri bution of the prepared films is investigated.X-ray diffraction (XRD) measurements indicate that in a certain range,increasing the sputtering power is conducive to the improvement of crystal quality and c-a xis orientation,and meanwhile,we also observe a decline in the c-axis orientation of the film dep osited at too much higher sputtering power.Simultaneous imaging of the surface topography,as well as the amplitude and phase of the piezoelectric response is performed by piezoresponse force microscopy (PF M),and the results show that the sputtering power has great influence on the piezoelectric activiti es and polarization orientation of ZnO films.The majority of the grains within the prepared films h as upward spontaneous polarization orientation,indicating that the top surfaces of the films are mainly O terminated.The amplitude of the out-of-plane piezeresponse depends on th e crystal quality and preferred orientation of the films.The film deposited at the sputtering power o f 150W exhibits better O-polarity uniformity and greater piezeresponse amplitude in the direction perp endicular to the film surface than those of the other samples.