Interfacial growth in HfOxNy gate dielectrics deposited using [(C2H5)2N]4Hf with O2 and NO

Abstract

The interface growth by oxygen diffusion has been investigated for 5 nm thick HfOxNy gate-quality dielectric films deposited on Si(100) by low-pressure pulsed metalorganic chemical vapor deposition. Analysis by x-ray photoelectron spectroscopy of the films deposited using the precursor tetrakis (diethylamido) hafnium with O2 showed that the films contained 4 at. % nitrogen. This increased to 11 at. % N when NO was used as the oxidant. Significant growth of the interface layer was observed for films exposed to air at ambient temperature and lower rates of growth were observed for vacuum annealed films and those with the higher N content. For films annealed in O2 at temperatures in the range 600–900 °C, the activation energies of the interfacial growth were 0.36 and 0.25 eV for N concentrations of 11 and 4 at. %, respectively. The results were interpreted in terms of atomic oxygen formation in the bulk and reaction at the interface. The increase in N incorporation from 4 to 11 at. % increases the crystallization temperature from between 500 and 600 °C to between 600 and 700 °C.