Epitaxially grown aluminum film for high-power surface acoustic wave devices

It is significant for surface acoustic wave (SAW) devices to improve resistance to stress-migration of aluminum (Al) electrodes. Epitaxially grown Al film was very useful for electrodes of SAW devices because of its resistance to stress-migration. Epitaxially grown Al film was formed on 36"-rotated Y-cut lithium tantalate (LiTaO/sub 3/) substrate by the dual-ion-beam sputtering (DIBS) with 500 eV ion energy. The epitaxial relationship was as follows: (111)[1O1l]Al/spl par/(O12)[100] LiTaO/sub 3/. SAW filters using epitaxially grown Al electrodes made it possible to improve the time to failure (TF) caused by stress-migration by over 100 times as compared to those of SAW filters using conventional polycrystalline aluminum-copper (Al-Cu) electrodes.