Discrete beta-Ta2O5 crystallite formation in reactively sputtered amorphous thin films

The crystallization of thin amorphous TaOx films formed by d.c, reactive sp uttering was investigated at temperatures from 500-700 degrees C. The films remained amorphous for ti mes up to 100 h at 500 degrees C. The formation of discrete, single crystallites of the orthorhombic beta-Ta2O5 phase was o bserved after annealing at 600 degrees C for times from 8-108 h. The crysta llites were 0.35 mu m x 0.35 mu m after 8 h and grew to approximately 2.5 m u m x 2.0 mu m after 108 h. A (2 0 0) fibre texture with a 6 degrees spread was observed. More rapid in-plane growth in the [0 1 0] direction resulted in a near-rectangular shape and is attributed to a ledge growth mechanism. Higher temperature anneals at 650 and 700 degrees C produced less-textured polycrystalline films with remnant amorphous regions. (C) 1998 Kluwer Acad emic Publishers.