Abstract
Transversal SAW(Surface Acoustic Wave) filters of 340MHz were fabricated on piezoelectric substrates of the LN $128^{\circ}$ Y-X wafers. Both of spacing and width of IDT were $1.435{\mu}m$. For improving the power durability characteristics, titanium layer was inserted between aluminum electrode and piezoelectric substrate since it has high density, low thermal expansion coefficient, and good adhesive properties. Power durability was evaluated with respect to the thickness of inserted titanium layer and the temperature of heat treatment. Power durability is improved with increasing the thickness of the inserted titanium layer. Moreover, it is remarkably improved by heat treatment at the temperature of $300^{\circ}C$.
중심주파수가 340MHz이고 $1.435{\mu}m$의 IDT 전극 폭과 간격을 가진 양방향 전송형 SAW필터를 LN $128^{\circ}$ Y-X 웨이퍼의 압전기판으로 제작하였다. 전력 내구성을 개선시키기 위한 방안으로 Al에 비해 밀도가 크고, 열팽창계수가 작으며 접착력이 좋은 Ti를 압전체기판과 전극물질인 Al 사이에 증착시켰다. Ti의 두께 및 열처리 온도가 내전력 특성에 미치는 영향을 분석하였는데, Ti층이 두꺼울수록 내전력이 개선되었으며, 특히 $300^{\circ}C$에서 열처리하였을 때 가장 우수하였다.
