Hydrogen annealing effect on the properties of thermal Ta2O5 on Si

The effect of post-metallization annealing in H-2 at 723 K on the properties of MOS capacitors with thermally grown thin (13-26 nm) Ta2O5 layers was investigated. It was established that the annealing effect strongly depends on the properties of the as-grown oxides and in particular on the oxidation temperature. The oxidation at higher temperatures (823 and 873 K) is beneficial for improving the electrical, breakdown and insulating properties of the films after annealing. A dielectric constant of 32 was reached for these layers and the magnitude of leakage current guarantees their application in 64 Mbit DRAM. The hydrogen annealing, however, additionally generates slow states in the oxide with a density of about 5 x 10(11) cm(-2). (C) 1999 Published by Elsevier Science Ltd. All rights reserved.