Inductively Coupled Plasma Etching of AlN Film for Fabrication of 5G Networks ＆ Devices: A Methodological Study

We addressed the inductively coupled plasma(ICP) etching technology of AlN piezoelectric film,an advanced electronic material for fabrication of film bulk acoustic resonator(FBAR) of 5 G networks & devices,particularly integrated RF front-end filter.The influence of the key ICP etching conditions,including the pressure,Cl₂/BCl₃ flow-rate ratio,ICP power,and RF bias power,on the etching-rate,geometry and surface morphology of the etched AIN-coating was investigated.The results show that the key ICP etching conditions all had a major impact.For example,as the ICP-power(BCl₃ flow-rate) increased,the etching-rate changed in an increase-decrease manner; a higher RF-bias power improved reaction-rate and sidewall steepness,accompanied by stronger anisotropic etching and more damages.Under the optimized ICP etching conditions,a prototyped air-gap FBAR filter,in a well-defined sandwich structure with steep flat sidewalls and smooth surfaces,was fabricated.