Crystallization of tantalum oxide formed by PLD

Tantalum oxide films were deposited on stainless steel by KrF excimer laser ablation of Ta and β-Ta2O5 plates at an oxygen pressure of 1 mPa–200 Pa. The effects of oxygen pressure on the deposition rate and chemical composition of the films were systematically investigated. The O/Ta atomic ratio and deposition rate increased with increasing oxygen pressure. At a pressure of 5 Pa, the O/Ta atomic ratio was nearly equal to the stoichiometric atomic ratio of Ta2O5. Although films deposited at room temperature at an oxygen pressure of 10 mPa–200 Pa were amorphous, the film deposited at 1 mPa was oriented to Ta(110). Crystallized δ-Ta2O5 films were obtained by annealing at 973 K for 3.6 ks under vacuum. There was no difference between the Ta and β-Ta2O5 targets in the pressure required for a stoichiometric film or the annealing temperature required for a crystalline film. Films deposited on a heated substrate were crystallized at a temperature approximately 300 K lower than the annealing temperature required for a crystalline film.