Nickel Germanide Thin Films by Atomic Layer Deposition

• Published in: Chemistry of materials Vol. 31; no. 14; pp. 5314 - 5319
• Main Authors: Väyrynen, Katja, Vihervaara, Anton, Hatanpää, Timo, Mattinen, Miika, Heikkilä, Mikko J, Mizohata, Kenichiro, Räisänen, Jyrki, Ritala, Mikko, Leskelä, Markku
• Format: Journal Article
• Language: English
• Published: American Chemical Society 23-07-2019
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.9b01877

This work presents preparation of nickel germanide (Ni2Ge) thin films by atomic layer deposition (ALD). The films were grown using NiCl2(tmpda) (tmpda = N,N,N′,N′,-tetramethyl-1,3-propanediamine) and tributylgermanium hydride serving as a new, efficient reducing agent. This is the first time ALD Ni x Ge y films are prepared directly upon the combination of two precursors and without any annealing treatment. Ni x Ge y is an important contact material for enabling Ge-based transistors and thus circumventing the scaling issues related to current microelectronics. The Ni2Ge process was examined at low temperatures of 160–200 °C. Self-limiting, saturative growth with a high growth rate of 0.91 Å/cycle was observed at 180 °C. The films were thoroughly analyzed in terms of morphology, crystallinity, composition, and resistivity. The Ni2Ge films were pure, with the sum of contaminants being less than 1 at. %. Owing to their high purity, the films exhibited low resistivity, suggesting suitability for contact applications.