Crystallization kinetics in amorphous (Zr0.62Al0.38)O-1.8 thin films

Thin films of Zr0.62Al0.38O1.8 are amorphous when deposited at room tempera ture by rf magnetron sputtering. Crystallization occurs during subsequent a nnealing in the temperature range of 700-1000 degreesC for times in the ran ge of 10 s-100 h. The crystallite size and the fraction of the sample that had crystallized were determined using x-ray diffraction. The films were fo und to initially develop a low density of fairly large (similar to8 nm) cry stallites, while subsequent heat treatment was found to increase the densit y rather than the size of the crystallites. Crystallization can be describe d with a first-order rate equation; the rate constant is exponential in tem perature with an effective activation energy of 6.6 eV. Films given a 10 s anneal at < 850 degreesC develop a substantial density of 8 nm grains, maki ng this specific composition an unsuitable candidate for replacing SiO2 as the gate oxide in hyperscaled field-effect transistors. (C) 2001 American V aciann Society.