The influence of tertiary butyl hydrazine as a co-reactant on the atomic layer deposition of silver

• Published in: Applied surface science Vol. 399; pp. 123 - 131
• Main Authors: Golrokhi, Zahra, Marshall, Paul A., Romani, Simon, Rushworth, Simon, Chalker, Paul R., Potter, Richard J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 31.03.2017
• Subjects: Atomic layer deposition; Self limiting; Silver thin films; Tertiary butyl hydrazine; Self limiting; Atomic layer deposition; Tertiary butyl hydrazine; Silver thin films
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2016.11.192

[Display omitted] •We demonstrate metallic silver growth by direct liquid injection thermal ALD.•A substituted hydrazine is used as a powerful reducing agent for the first time.•The hydrazine extends the ALD temperature window compared with alcohol.•Hydrazine promotes a more planar growth mode compared to alcohol.•Film adhesion is improved using hydrazine compared with alcohol. Ultra-thin conformal silver films are the focus of development for applications such as anti-microbial surfaces, optical components and electronic devices. In this study, metallic silver films have been deposited using direct liquid injection thermal atomic layer deposition (ALD) using (hfac)Ag(1,5-COD) ((hexafluoroacetylacetonato)silver(I)(1,5-cyclooctadiene)) as the metal source and tertiary butyl hydrazine (TBH) as a co-reactant. The process provides a 23°C wide ‘self-limiting’ ALD temperature window between 105 and 128°C, which is significantly wider than is achievable using alcohol as a co-reactant. A mass deposition rate of ∼20ng/cm2/cycle (∼0.18Å/cycle) is observed under self-limiting growth conditions. The resulting films are crystalline metallic silver with a near planar film-like morphology which are electrically conductive. By extending the temperature range of the ALD window by the use of TBH as a co-reactant, it is envisaged that the process will be exploitable in a range of new low temperature applications.