Plasma-Enhanced Atomic Layer Deposition of Silver Using Ag(fod)(PEt₃) and NH₃-Plasma

Abstract

A plasma-enhanced atomic layer deposition (ALD) process using the Ag(fod)(PEt 3 ) precursor [(triethylphosphine) (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5octanedionate)silver(I)] in combination with NH 3 -plasma is reported. The steady growth rate of the reported process (0.24 ± 0.03 nm/cycle) was found to be 6 times larger than that of the previously reported Ag ALD process based on the same precursor in combination with H 2 -plasma (0.04 ± 0.02 nm/ cycle). The ALD characteristics of the H 2 -plasma and NH 3plasma processes were verified. The deposited Ag films were polycrystalline face-centered cubic Ag for both processes. The film morphology was investigated by ex situ scanning electron microscopy and grazing-incidence small-angle X-ray scattering, and it was found that films grown with the NH 3 -plasma process exhibit a much higher particle areal density and smaller particle sizes on oxide substrates compared to those deposited using the H 2 -plasma process. This control over morphology of the deposited Ag is important for applications in catalysis and plasmonics. While films grown with the H 2 -plasma process had oxygen impurities (∼9 atom %) in the bulk, the main impurity for the NH 3 -plasma process was nitrogen (∼7 atom %). In situ Fourier transform infrared spectroscopy experiments suggest that these nitrogen impurities are derived from NH x surface groups generated during the NH 3 -plasma, which interact with the precursor molecules during the precursor pulse. We propose that the reaction of these surface groups with the precursor leads to additional deposition of Ag atoms during the precursor pulse compared to the H 2 -plasma process, which explains the enhanced growth rate of the NH 3 -plasma process.

Antibacterial and Osteogenic Properties of Ag Nanoparticles and Ag/TiO2 Nanostructures Prepared by Atomic Layer Deposition

“…The results on a detailed study of the composition of the ALD Ag NPs by XPS showed that they contain a small amount of oxygen, carbon, fluorine, and phosphorus in the form of precursor residues. Similar results for ALD coatings were obtained earlier by other researchers [ 16 , 24 , 25 ]. However, the presence of such impurities does not noticeably affect the antibacterial properties of silver [ 34 ].…”

“…In view of the above, it was necessary to find another way to increase the amount of Ag(fod)(PEt 3 ) entering the reactor to achieve optimal conditions for silver synthesis. The literature analysis showed [ 24 ] that it is useful to conduct several successive pulses of Ag(fod)(PEt 3 ) in one ALD cycle. In our study, we tested regimes with 1, 3, 5, and 7 pulses of 4 s each ( Figure 1 b, normal pulses).…”

Atomic Layer Deposition of Cobalt Using H2-, N2-, and NH3-Based Plasmas: On the Role of the Co-reactant

“… 69 − 71 Notably, the role of N-containing surface species has previously been addressed for the ALD of Pt and Ag using N 2 or NH 3 plasmas. 19 , 72 , 73 Specifically, N-containing species were proposed to adsorb during the N 2 or NH 3 plasma exposures and to react with the precursor during the subsequent precursor dose.…”

Plasma-Enhanced Atomic Layer Deposition of Cobalt and Cobalt Nitride: What Controls the Incorporation of Nitrogen?

“…0.6 V, such as noble metals and platinum group metals, are highly unstable. As a result of this, among others, Pt, Ir, and Ag have been deposited in their metallic state. Finally, while species with intermediate potentials such as W can be deposited as nitrides, the latter have limited thermodynamic stability and decompose at temperatures below 1000 °C.…”