| AVS 64th International Symposium & Exhibition | |
| Thin Films Division | Tuesday Sessions |
| Session TF-TuA |
| Session: | ALD Precursors and Surface Reactions |
| Presenter: | Zhengning Gao, Washington University in St. Louis |
| Authors: | Z.N. Gao, Washington University in St. Louis R. Kanjolia, EMD Performance Materials P. Banerjee, Washington University in St. Louis |
| Correspondent: | Click to Email |
The precursor 2, 3 - dimethyl butadiene Ruthenium tri-carbonyl (Ru(DMBD)(CO)3), is a volatile molecule with favorable properties for the deposition of both Ru and RuO2 films via ALD.1 An intriguing aspect of this precursor is its asymmetric molecular structure with the DMBD ligand coordinated to one side of the Ru4+ center, while the 3 carbonyl groups are bonded to the opposite side. This makes the molecule an attractive candidate to study using in situ downstream quadrupole mass spectrometry (QMS) since, the release of DMBD vs. carbonyl groups during ALD half-reactions can provide a particularly descriptive view at the atomic level of how Ru(DMBD)(CO)3 interacts with the substrate.
In this talk, we will discuss the mechanism of ALD of Ru thin films using Ru(DMBD)(CO)3 and H2O. The QMS signal of the Ru(DMBD)(CO)3 consists of three distinct species. First, the mass-to-charge ratio (m/e) of 67 corresponds to the DMBD ligand dissociating from the molecule2. Second, a strong m/e = 16 is also observed as the DMBD further cracks into smaller fragments. Finally, m/e = 44 is observed and is related to CO2 and HCOOH formation from the reaction of the tri-carbonyl groups with H2O.3 The QMS signal of these three species will be discussed in the context of varying process parameters such as Ru(DMBD)(CO)3 and H2O pulse times and the temperature of the ALD process. Additionally, ex situ film characterization including atomic force microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectrum and resistivity measurements will be presented to correlate the process signatures obtained via QMS to the film type, morphology and electrical properties.
References:
1. Austin, D. Z.; Jenkins, M. A.; Allman, D.; Hose, S.; Price, D.; Dezelah, C. L.; Conley, J. F., Atomic Layer Deposition of Ruthenium and Ruthenium Oxide Using a Zero Oxidation State Precursor. Chem. Mater. 2017.
2. Chiang, C.-M.; Rowe, J.; Malic, R.; Sen, A.; Steigerwald, M.; Mills, A., A new CVD reaction for atomic layer deposition of silicon. Applied surface science 1996,107, 189-196.
3. Rosenberg, S. G.; Barclay, M.; Fairbrother, D. H., Electron beam induced reactions of adsorbed cobalt tricarbonyl nitrosyl (Co (CO) 3NO) molecules. The Journal of Physical Chemistry C 2013,117 (31), 16053-16064.