Dresden 2014 – scientific programme
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O: Fachverband Oberflächenphysik
O 96: Atomic Layer Deposition (DS jpointly with O)
O 96.7: Talk
Friday, April 4, 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.