• Hämäläinen, Jani Marko Antero
• Gao, Feng
• Mattinen, Miika Juhana
• Jalkanen, Pasi
• Leskelä, Markku Antero
• Mizohata, Kenichiro
• Ritala, Mikko
• Räisänen, Jyrki
• Puurunen, Riikka L.

Abstract

Nucleation and conformality are important issues, when depositing thin films for demanding applications. In this study, iridium and iridium dioxide (IrO 2 ) films were deposited by atomic layer deposition (ALD), using five different processes. Different reactants, namely, O 2 , air, consecutive O 2 and H 2 (O 2 +H 2 ), and consecutive O 3 and H 2 (O 3 +H 2 ) pulses were used with iridium acetylacetonate [Ir(acac) 3 ] to deposit Ir, while IrO 2 was deposited using Ir(acac) 3 and O 3 . 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 O 2 +H 2 > air ≈ O 2 > O 3 > O 3 +H 2 , whereas the order of conformality, from the best to the worst, was O 3 +H 2 > O 2 +H 2 > O 2 > O 3 . In the O 3 process, a change in film composition from IrO 2 to 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.

Topics

• thin film
• Platinum
• atomic layer deposition
• Iridium