atomic layer deposition abbr., ALD; ALE otherwise atomic layer epitaxy (rus. осаждение атомных слоев otherwise атомно-слоевое осаждение; молекулярное наслаивание) — thin film deposition technique that is based on the cyclic use of self-limited chemical reactions for precise control of layer thickness.

Description

The atomic layer deposition technique, originally called atomic layer epitaxy, was proposed by Tuomo Suntola (Finland) in 1977. This technique has much in common with chemical vapour deposition, the only difference being that atomic layer deposition involves chemical reactions where precursors react with the surface sequentially (repeatedly) and do not interact with each other directly (do not contact). Precursors are separated by way of nitrogen or argon purging. While the process involves self-limited reactions, the total thickness of deposited layers depends on the number of cycles rather than the length of the reaction, and the thickness of each individual layer can be controlled with very high precision.

Atomic layer deposition is used with several types of films, including films of different oxides (Al2O3, TiO2, SnO2, ZnO, HfO2), nitrides (TiN, TaN, WN, NbN), metals (Ru, Ir, Pt) and sulphides (e.g., ZnS). Unfortunately, we still lack cheap technologies for growing such technologically vital materials as Si, Ge, Si3N4 and some multicomponent oxides.

Illustrations

ALD technology schematic representation. 
ALD technology schematic representation. Author: A. R. Barron, Houston, USA. Quoted from cnx.org, Open Educational Resource.

Authors

  • Saranin Alexander A.
  • Naymushina Daria A.

Sources

  1. Atomic layer deposition // Wikipedia, the free Encyclopedia. — http://en.wikipedia.org/wiki/Atomic_layer_deposition (reference date: 27.06.2010).
  2. Atomic layer epitaxy // Wikipedia, the free Encyclopedia. — http://en.wikipedia.org/wiki/Atomic_layer_epitaxy (reference date: 27.06.2010).

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