TECHNOLOGIESALD
ALD
Atomic layer deposition (ALD) is used to fabricate ultra thin and conformal thin film structures for many thin film device applications. The ALD technique builds new surfaces by sequential self- limiting reactions between highly reactive gas molecules and active sites on surfaces.

The growth of material layers by ALD consists of repeating the following steps:
1. Expose of the precursor (typically an organometallic compound) and purge to remove the non-reacted precursors and the gaseous reaction by-products.
2. Expose of the reactant and purge to remove the non-reacted reactants and the reaction by- products.
Each reaction cycle adds a given amount of material to the surface, referred to as the growth per cycle. To grow a material layer, reaction cycles are repeated as many as required for the desired film thickness. One cycle may take time from 0.5 sec. to a few seconds and deposit between 0.1 and 3 Å of film thickness. Due to the self-terminating reactions, ALD is a surface- controlled process, where process parameters other than the precursors, substrate, and temperature have little or no influence. And, because of the surface control, ALD-grown films are extremely conformal and uniform in thickness. These thin films can also be used in correlation with other common fabrication methods.

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