Plasma Enhanced Atomic Layer Deposition of Ruthenium Thin Films Using Isopropylmethylbenzene-Cyclohexadiene-Ruthenium and NH3 Plasma

Abstract

Ruthenium (Ru) thin films were successfully grown on the TiN substrate using plasma enhanced atomic layer deposition (PEALD) by using a zero metal valence precursor, IMBCHRu [(eta 6-1-Isopropyl-4-MethylBenzene)(eta 4-CycloHexa-1,3-diene) Ruthenium (0)] and direct plasma of ammonia (NH3) as a reactant at the substrate temperature ranging from 140 and 400 degrees C. The wide atomic layer deposition (ALD) temperature window from 225 to 400 degrees C was shown and a high growth rate of 0.094 nm/cycle at the ALD temperature window was obtained, which is twice that of PEALD Ru results deposited by Cp (Cyclopentaldienyl)-based Ru precursors previously reported. No incubation cycle for the growth on the TiN underlayer was observed, indicating the fast nucleation of Ru. The PEALD-Ru films formed polycrystalline and columnar grain structures with a hexagonal-close-packed phase that was confirmed by X-ray diffractometry and transmission electron microscopy analysis. Its resistivity was dependent on the microstructural features characterized by grain size and crystallinity as well as its density, which could be controlled by varying the deposition parameters such as deposition temperature and reactant pulsing condition. Resistivity of similar to 12 mu Omega cm was obtained at the deposition temperature as low as 225 degrees C by optimizing (NH3) plasma power and pulsing time. (c) 2010 The Electrochemical Society. [DOI: 10.1149/1.3515320] All rights reserved.