Nucleation and Conformality of Iridium and Iridium Oxide Thin Films Grown by Atomic Layer Deposition.
Nucleation and conformality are important issues, when depositing thin films for demanding applications. In this study, iridium and iridium dioxide (IrO2) films were deposited by atomic layer deposition (ALD), using five different processes. Different reactants, namely, O2, air, consecutive O2and H2(O2+ H2), and consecutive O3and H2(O3+ H2) pulses were used with iridium acetylacetonate [Ir(acac)3] to deposit Ir, while IrO2was deposited using Ir(acac)3and O3. Nucleation was studied using a combination of methods for film thickness and morphology evaluation. In conformality studies, microscopic lateral high-aspect-ratio (LHAR) test structures, specifically designed for accurate and versatile conformality testing of ALD films, were used. The order of nucleation, from the fastest to the slowest, was O2+ H2> air ≈ O2> O3> O3+ H2, whereas the order of conformality, from the best to the worst, was O3+ H2> O2+ H2> O2> O3. In the O3process, a change in film composition from IrO2to metallic Ir was seen inside the LHAR structures. Compared to the previous reports on ALD of platinum-group metals, most of the studied processes showed good to excellent results.
Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55, FI-00014 Helsinki, Finland.
Miika
M
Mattinen
Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55, FI-00014 Helsinki, Finland.
Jani
J
Hämäläinen
VTT Technical Research Centre of Finland , P.O. Box 1000, FI-02044 Espoo, Finland.
Feng
F
Gao
Division of Materials Physics, Department of Physics, University of Helsinki , P.O. Box 43, FI-00014 Helsinki, Finland.
Pasi
P
Jalkanen
Division of Materials Physics, Department of Physics, University of Helsinki , P.O. Box 43, FI-00014 Helsinki, Finland.
Kenichiro
K
Mizohata
Division of Materials Physics, Department of Physics, University of Helsinki , P.O. Box 43, FI-00014 Helsinki, Finland.
Jyrki
J
Räisänen
VTT Technical Research Centre of Finland , P.O. Box 1000, FI-02044 Espoo, Finland.
Riikka L
RL
Puurunen
Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55, FI-00014 Helsinki, Finland.
Mikko
M
Ritala
Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55, FI-00014 Helsinki, Finland.
Markku
M
Leskelä