General Description

Atomic Layer Deposition (ALD) is a highly reproducible thin-film deposition technique that deposits materials layer by layer with atomic-scale (Ångström/monolayer) precision through sequential, self-limiting reactions of alternating gaseous precursors. The process is based on pulsing precursor vapors, allowing nearly one atomic layer to form during each cycle, while excess reactants and reaction by-products are purged between pulses. Since each ALD cycle deposits at most a single monolayer, the film thickness and composition can be precisely controlled by the number of deposition cycles. The self-limiting surface chemistry produces extremely smooth, low-impurity films with excellent step coverage and outstanding conformality on complex three-dimensional structures with high aspect ratios. Plasma-enhanced/low-temperature ALD extends these advantages to thermally sensitive substrates, such as organic polymers, enabling surface functionalization, the fabrication of inorganic–organic hybrid materials, and gas diffusion barrier coatings. ALD is a key technology for semiconductor manufacturing, nanomaterial synthesis, and many other applications requiring ultrathin, conformal, and precisely controlled thin films.