Improving the lifetime of surface acoustic wave filters requires reduction of electromigration effects. We report on the growth mechanism of AlCu2% films deposited by the e-beam physical vapor deposition technique. The state of the art shows that the introduction of an underlayer that alters the surface free energy can change a film’s growth mode or improve the earliest stages of film formation. In this work, this will be achieved by using an ultra-thin (<5 nm) Ta underlayer between the LiNbO3 substrate and the AlCu2% film. The effects of the Ta underlayer on the microstructure of AlCu2%/LiNbO3 films are investigated. An increase in the surface energy of the LiNbO3 substrate is observed with the addition of a 1.3 nm thick Ta underlayer. The crystalline quality of the AlCu2% thin film with a Ta underlayer is measured using XRD techniques. A post-deposition heat processing technique is also used to recrystallize the films. The AlCu2%/1.3Ta/LiNbO3 film annealed at 250 °C improved the electrode quality with the increase of 16% of the grain size.

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