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DS: Fachverband Dünne Schichten

DS 49: Atomic Layer Deposition

DS 49.7: Vortrag

Freitag, 4. April 2014, 11:30–11:45, CHE 91

Ta₂O₅ by thermal-activated ALD — •Marcel Junige¹, Ralf Tanner¹, Christian Wenger², Grzegorz Lupina², Matthias Albert¹, and Johann W. Bartha¹ — ¹Technische Universität Dresden — ²IHP GmbH, Frankfurt (Oder), Germany

Ta₂O₅ is a dielectric material with a comparably high permittivity as well as refractive index and thus gains interest for several electronic or optical applications. Atomic Layer Deposition (ALD) is a vacuum technique, which enables the coating of complex-shaped surfaces by alternatively applying self-terminating physicochemical reactions.

We investigated the thermal-activated ALD using the halogen-free metal-organic precursor TBTEMT and ozone gas (O₃) as co-reactant at an actual deposition temperature of 215 ^∘C. We pre-heated a Silicon sample for 30 min at the respective process conditions and pre-cleaned the initial surface for 180 s in O₃ in order to remove ambient carbon contaminations prior to the ALD.

In-situ real-time Spectroscopic Ellipsometry with a highest possible sampling rate of ca. 1 data point/s confirmed a timewise saturation of the TBTEMT adsorption and of the subsequent ligand removal. An ellipsometric multi-time analysis of a deposition run with 100 ALD cycles determined the homogeneous growth per cycle around 0.64 Å/cycle, the refractive index at 500 nm wavelength around 2.1 and the Tauc optical band gap around 4.3 eV, indicating an amorphous phase. In-vacuo X-ray Photoelectron Spectroscopy revealed a Ta₂O₅ film of high purity with a tantalum-to-oxygen ratio of (29:71) at.% as well as carbon and nitrogen contaminants below the detection limit.