Increment of the Dielectric Constant of Ta2O5 Thin Films by Retarding Interface Oxide Growth on Si Substrates

Abstract

The improved electrical properties of tantalum oxides grown by plasma-enhanced atomic layer deposition (PEALD) are presented. In PEALD, oxygen radicals were served as a reactant of Ta(OC(2)H(5))(5) at a deposition temperature of 260 degrees C. The interface oxide layer, which was formed during the initial stage of the PEALD, retards its further growth during the annealing process at 700 degrees C for 2 min in O(2) ambient, and is thought to be not pure SiO(2) but Ta(x)Si(y)O. The stoichiometry of the as-deposited film is oxygen-rich, having no hydrocarbon impurity. As a result, on the films with a thickness of T(SiO2.eq) = 1.7 nm, the leakage current density, dominated by Schottky emission, reduces to 3.38 x 10(-7) A/cm(2) at 1 MV/cm, and the dielectric constant is obtained as high as epsilon(r) = 38 even after the annealing process. (C) 2001 The Electrochemical Society. [DOI: 10.1149/1.1377835] All rights reserved.