Atomic Layer Deposition (ALD) Process

Deposition methods towards the fabrication of thin films are classified according the nature of the methodology and the target to deposit. Atomic Layer Deposition (ALD) is a chemical vapor phase deposition technique that allows the production of a variety of thin films.

It is a well-known process in semiconductors and in energy conversion technologies. According to cited articles, ALD is potentially more convenient technique than its chemical and vapor homologues due to its conformality and control over materials thickness and composition. Generally, an ALD process consists of sequentially alternating pulses of chemical precursors in gas state that react with the substrate.

The ALD system of the Nanoquim Platform Service (Savannah from Cambridge Nanotech) counts with 6 precursor lines (nowadays: H₂O, O₃, TMA, Ce(thd)₄, ferrocene) and is designed to deposit pinhole free coatings that are perfectly uniform in thickness, even inside cavities, resulting in high quality thin films on substrates with ultra-high aspect ratios. Typical thicknesses are 1 Å - 1000 Å and rates of < 0.1 - 1 Å/s.

References:

Toshiyuki, K. (2014). "Physics on development of open-air atmospheric pressure thin film fabrication technique using mist droplets: Control of precursor flow." Japanese Journal of Applied Physics 53(5S1): 05FF08.

Thirumalai, J. (2017). Introductory Chapter: The Prominence of Thin Film Science in Technological Scale. Thin Film Processes - Artifacts on Surface Phenomena and Technological Facets. J. Thirumalai. Rijeka, InTech: Ch. 01.            

Johnson, R. W., et al. (2014). "A brief review of atomic layer deposition: from fundamentals to applications." Materials Today 17(5): 236-246.