ALD Process
The growth of material layers by ALD consists of repeating the following characteristic four steps:
- Exposure of the first precursor, typically an organometallic compound.
- Purge or evacuation of the reaction chamber to remove the non-reacted precursors and the gaseous reaction by-products.
- Exposure of the second precursor – or another treatment to activate the surface again for the reaction of the first precursor, such as a plasma.
- Purge or evacuation of the reaction chamber.
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 s 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.
Read more about this topic: Atomic Layer Deposition
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