표면탄성파 필터 제작을 위한 Pt 박막 식각

초록

The inductively coupled plasma(ICP) etching process was selected to fabricate RF Surface Acoustic Wave(SAW) filters and a Pt thin film was sputtered on a LiTaO3 substrate applied to electrode materials to reduce the spurious response and improve the power durability. Steep sidewall pattern was achieved employing C4F8/Ar/Cl2 gas chemistry. We investigated an etching mechanism and parameter dependence of the Pt thin film about C4F8 addition. Sidewall etch angle was about 80° at the C4F8 20% mixing ratio. Fabricated SAW filter is consists of some series and parallel arm SAW resonators which work as impedance elements and show capacitance characteristics at out of the passband. It can be modified for 800~900 MHz RF filters. External matching circuits were unnecessary.