Fabrication Of Single-crystalline AlN-based FBAR

In the past decades,rapid growth of wireless communication has made conventional filter beyond RF front-end's demand for high frequency,small volume,and capability of integration.the-state-of-art technology thin-film bulk acoustic resonator?FBAR?succeed in RF filter solution taking advantages of small size,lower loss,great power capacity and compatibility to semiconductor IC facilities.Also,property like high sensitivity,energy efficiency and quick response inspire FBAR sensors wide application in transducing&measuring field.Now,FBAR technology have achieved such worldwide use but still face challenge of improving its performance that is largely restricted by key layer materials' property.Researches at home is at its early beginning so that independent development is literally a big problem.Under this circumstances,this study conducted research on affect of FBAR each layer materials' property on device performance,and combined simulation results with measured data discussing the competition of AlN film as piezoelectric material.A novel fabrication process which introduced high-performance crystalline AlN film was sequentially presented.Finally,we completed fabrication and electrical test.This study research on simulation design,materials preparation,device processing and performance test in system which gain great result and innovation:Firstly,we established physical model of composite membrane FBAR and simulated layer material physical parameters by Advanced Design System?ADS?,such as c₃₃^E,e_Z3,?,?_zz^eof piezoelectric layer and c₁₁,? of metallic layer.We got the regular of how those parameters influence FOM,k_eff² and Q,followed by mechanism interpretation.Then,we come up with the method of epitaxially growth high-performance crystalline AlN film that put pulse laser deposition?PLD?technique into use and reform the processing of FBAR fabrication that taking crystalline AlN film as piezoelectric material.The core of this process to obtain air cavity which trap the acoustic energy inside the metal/AlN/metal sandwich membrane by substrate transferring method;During solving the key technical problem,we cope with the pattern precision issue in positive photoresist lift-off process,achieving reliable bonding for AlN film and Si substrate,working on deep Si etching processing to make air cavity release epitaxial substrate and fast AlN dry etching processing to get electrical via.In the end,we measured the device's transmission characteristic using vector network analyzer?VNA?,demonstrated this processing we put forward to be feasible.