N Noémi Leick

Atomic layer deposition of Ru from CpRu(CO)2Et using O2 gas and O2 plasma

The metalorganic precursor cyclopentadienylethyl(dicarbonyl)ruthenium (CpRu(CO)2Et) was used to develop an atomic layer deposition (ALD) process for ruthenium. O2 gas and O2 plasma were employed as reactants. For both processes, thermal and plasma-assisted ALD, a relatively high growth-per-cycle of ∼1 A was obtained. The Ru films were dense and polycrystalline, regardless of the reactant, yielding a resistivity of ∼16 μΩ cm. The O2 plasma not only enhanced the Ru nucleation on the TiN substrates but also led to an increased roughness compared to thermal ALD.

In situ spectroscopic ellipsometry during atomic layer deposition of Pt, Ru and Pd

The preparation of ultra-thin platinum-group metal films, such as Pt, Ru and Pd, by atomic layer deposition (ALD) was monitored in situ using spectroscopic ellipsometry in the photon energy range of 0.75–5 eV. The metals’ dielectric function was parametrized using a ‘flexible’ Kramers–Kronig consistent dielectric function because it was able to provide accurate curve shape control over the optical response of the metals. From this dielectric function, it was possible to extract the film thickness values during the ALD process. The important ALD process parameters, such as the nucleation period and growth per cycle of Pt, Ru and Pd could be determined from the thickness evolution. In addition to process parameters, the film resistivity in particular could be extracted from the modeled dielectric function. Spectroscopic ellipsometry thereby revealed itself as a feasible and valuable technique to be used in research and development applications, as well as for process monitoring during ALD.