随着单片微波技术的飞速发展，微波射频滤波器成为了微波电子系统小型化的瓶颈。微波电子系统集成化小型化的需求，使得薄膜体声波谐振器件（FBAR）成为该领域最有前途的发展方向。常规微型薄膜表面声波（SAW）和体声波（BAW）谐振器和滤波器等，都是在单晶压电材料的基础上制备的，比如石英，LiNbO3和LiTaO3等。这些材料都是用切割—研磨—减薄方法制作的，由于谐振频率与材料的厚度有关，频率越高要求的材料厚度越薄。按照BAW谐振器工作中心频率f与纵向伸延模式声速Vph和压电层厚度d的关系式f=Vph/2d计算，这些单晶体声速约为2500-4500m/s。如谐振频率要达到1GHz，就需要晶片厚度d=1.25-2.25μm，这一厚度的晶片加工和封装显然是不能实现的。由于AlN薄膜具有很高的声速，如果厚度在μm到nm量级，压电层的工作频率就可以达到500MHz到10GHz。

Aluminum nitride (AlN) possesses some outstanding properties, such as high hardness, high thermal conductivity, and high electrical resistivity. In addition, the close value of thermal expansion coefficient to that of Si make AlN an attractive material in the microelectronics field. Owing to these unique properties,AlN films have been reported as an excellent candidate for silicon-on-insulator materials, metal-insulator-semiconductor materials, and cap layer for GaAs substrate. Furthermore, AlN films are highly transparent in the visible wavelength region, and thus they have potential application for optical coating materials. AlN thin films have been prepared with various methods. Among deposition methods, the deposition techniques using an ion beam, such as ion-beam assisted deposition and ion-beam sputtering deposition, control of the ion bombardment parameters such as ion beam energy, ion beam current density, and incident angle to substrates. The present authors have succeeded in preparing AlN film at near room temperature.