Chemical Infiltration during Atomic Layer Deposition: Metalation of Porphyrins as Model Substrates

摘要

Atomic layer deposition (ALD) is a gas-phase deposition process based on successive self-terminating gas-solid reactions. During the process, the template substrate is exposed to precursor molecules from the gas phase, which ideally promotes adsorption of a monolayer on the surface. After purging the excess precursor and subsequent exposure to a second gaseous precursor, reaction on the surface of the substrate leads to formation of a layer of the desired material. The layer thickness is controlled by the number of the reaction cycles. Owing to the precise thickness control and broad range of operating temperatures, ALD has recently been used for coating various structures, including thermally and chemically sensitive organic and biological macromole-cules. Much work has also been performed to develop new precursors and new processes to increase the versatility of ALD. For example, a number of studies have been devoted to the investigation of the interface chemistry during the deposition process to achieve better control over the deposition rate and the area selectivity of the deposition. Several reviews about ALD have been recently published.