Atomic layer deposition

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Atomic Layer Deposition (ALD) is a self-limiting, sequential surface chemistry that deposits conformal thin-films of materials onto substrates of varying compositions. ALD is similar in chemistry to chemical vapor deposition (CVD), except that the ALD reaction breaks the CVD reaction into two half-reactions, keeping the precursor materials separate during the reaction. ALD film growth is self-limited and based on surface reactions, which makes achieving atomic scale deposition control possible. By keeping the precursors separate throughout the coating process, atomic layer control of film grown can be obtained as fine as ~ 0.1 angstroms per monolayer.

ALD has unique advantages over other thin film deposition techniques, as ALD grown films are conformal, pin-hole free, and chemically bonded to the substrate. With ALD it is possible to deposit coatings perfectly uniform in thickness inside deep trenches, porous media and around particles. The film thickness range is usually 1-500 nm.

ALD can be used to deposit several types of thin films, including various ceramics, from conductors to insulators.

[edit] References

• An animation of the ALD process is shown here [1]
• Mikko Ritala; Markku Leskelä (March 1999). "Atomic layer epitaxy—a valuable tool for nanotechnology?". Nanotechnology 10 (1): 19–24.