Atomic Layer Deposition

Abstract

Atomic layer deposition (ALD) is a key coating technology which enables conformal coatings on high aspect ratio substrates. In addition, it allows for a precise thickness control of thin films, multilayers, and nanolaminates. It is a chemical coating technology where the precursors are introduced sequentially in the reactor or are spatially separated. Herein, basic principles of ALD are introduced, reactor geometries are overviewed, and typical ALD materials and applications are summarized. ALD thin films are one pillar of modern computer technologies where ultra‐thin, conformal coatings with exceptional physical, electrical, and chemical properties are essential. Numerous emerging applications have been demonstrated and some are already in mass‐production. Precursor and process development, tool design and engineering, extensive thin‐film optimization, the search for better materials and composites combined with expert knowledge in the application fields have led to this success.

Plasma-Enhanced Atomic Layer Deposition of HfO2 with Substrate Biasing: Thin Films for High-Reflective Mirrors

“…Atomic layer deposition (ALD) has gained importance due to the ability to coat wide-area surfaces with excellent uniformity and grow conformal coatings on high aspect ratio nanostructured substrates. − This technology is a subclass of the CVD technique where gas-phase precursors are sequentially introduced into the deposition chamber. The layer-by-layer growth in a self-limiting manner enables ALD to deposit thin films with a precise thickness control . ALD films using thermally activated reactions of reactants with surface functional groups constitute thermal ALD processes (TALD), whereas in plasma-enhanced atomic layer deposition (PEALD), the high reactivity of plasma species enables low-temperature deposition. − …”

“…The layer-by-layer growth in a self-limiting manner enables ALD to deposit thin films with a precise thickness control . ALD films using thermally activated reactions of reactants with surface functional groups constitute thermal ALD processes (TALD), whereas in plasma-enhanced atomic layer deposition (PEALD), the high reactivity of plasma species enables low-temperature deposition. − …”