MOCVD of Ni and Ni₃C films from Ni(dmen)₂(tfa)₂

Abstract

In this study results are reported on the transport and decomposition behavior of a trifluoroacetato complex of formula Ni(dmen)(2)(tfa)(2), in view of its use as a precursor for the MOCVD of Ni. It is shown that Ni(dmen)(2)(tfa)(2) can be sublimed up to 190 degrees C without decomposition with, however, a relatively low partial pressure. MOCVD of Ni films from this precursor on silicon and on silica are also reported, performed at temperatures varying between 275 degrees C and 350 degrees C. It was found that the process is kinetically controlled. Films are crystalline, present a granular morphology and, depending on operating conditions, are composed of Ni, of metastable nickel carbide Ni(3)C or of mixtures thereof. The carbon content decreases with decreasing deposition temperature and with increasing hydrogen flow rate. It is also higher in the first deposited layers, revealing a different decomposition mechanism of the precursor on an inert relatively to a metallic surface. Although processing conditions have not been optimized, MOCVD of Ni films from this family of complexes appears promising. However, modifications of the structure of Ni(dmen)(2)(tfa)(2) are necessary to increase its volatility and consequently the growth rate of the films.