Dresden 2003 – scientific programme

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DS: Dünne Schichten

DS 24: Poster

DS 24.49: Poster

Tuesday, March 25, 2003, 14:30–17:00, P2a

Microstructure of Al/Ti metallization layers — •Matthias Hofmann, Thomas Gemming, Siegfried Menzel, and Klaus Wetzig — Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, Dresden, Germany

Changes of the microstructure of Al/Ti multilayer metallization systems for surface acoustic wave devices during heat treatment are investigated with transmission electron microscopy and the method of histogram analysis of electron spectroscopic imaging.

The Al/Ti layers were deposited by electron-beam evaporation on different piezoelectric substrate materials: Quartz (SiO₂), LiTaO₃ and LiNbO₃. The layers show columnar grains, and a reaction between the Al and Ti layers could not be detected in the as-deposited state. However, after annealing at 450C for five hours in air, we found the Ti interlayers were completely dissolved. On the SiO₂ substrate the adhesive Ti bottom layer was also dissolved. In the course of this reaction, the microstructure of the Al layers transforms to globular grains consisting of Al and the intermetallic phase Al₃Ti. Our results demonstrate the feasibility of forming intermetallic metallizations (Al₃Ti) directly from deposited layers of elemental metals (Al, Ti).