Talk:Atomic layer deposition

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This article may be too technical for a general audience. Please help improve this article by providing more context and better explanations of technical details to make it more accessible, without removing technical details.

[edit] Merge ALD and ALE

In response to Gjmulhol, ALD and ALE are essentially the same. ALD is self-limiting as well, with the first layer deposited on the substrate and the subsequent layers chemisorbed on each other via sequential half-reactions.

There is absolutely no reason to have two different articles. ALD is essentially the same as ALE. I see ALD much more often in literature, so I would suggest that the ALE article be merged with the ALD article.

These two processes are in fact the same and should be merged. Gjmulhol 19:43, 4 August 2006 (UTC)

I would suggest hyperlinking the word "epitaxy" to the wikipedia article of the same name. [[User:jcrowland] 17 august 2006 (UFl)]

After investigating further with some of the original inventors of the process, I believe that these topics while subtly distinct are deeply related. ALE is a self limiting process where a layer is bonded to the surface while ALD is a similar process where every layer and pulse of precursor connect react with each other to form a single layer composed of organized molecules based on the two precursors. Gjmulhol

I do not understand the "subtle distinction" between these two processes. As far as I can tell, they're the same. --Smack (talk) 05:08, 22 January 2007 (UTC)

ALE is the same thing as ALD, for the most part. ALE is the original name for the process, coined by Suntola in the 70's. Epitaxy implies a crystalline structure growth, whereas deposition does not. ALD is actually a more technically correct term for what is being designed in today's fabs since polycrystalline or even amorphous growth can come out of ALD. In the current literature the use of ALE has almost all but died off. The only people that typically use ALE are the Finns, but it is because the process was designed there, so old habits die hard. Milehighmounty 04:52, 18 February 2007 (UTC)

There is a distinction between the two, as said before the fact that ALE is per definition Epitaxial, which is not always the case for ALD. ALE is like ALD selflimiting, however, ALE is commonly used to denote Atomic Layer Doping, however ALE is used to prevent confusion, specifically by Murota et al. I am currently doing research in this area and therefore thankfull for the slight difference in it's definition.

[edit] ALD citations needed

Many citations are needed on the ALD page. While some of the claims made in the article may be legitimate, many are subject to debate. Most clearly, thickness control has been shown to be as low as 1 angstrom, but I have never seen control down to .1 (which is far smaller than the radius of most molecules). Also, recent literature suggests that the process is only self-limiting within certain exposure time ranges. Thus, it is incomplete to say that the process itself is entirely self-limiting. Gjmulhol 19:43, 4 August 2006 (UTC)

The Atomic Layer growth rate is best reported as 0.1 Angstrom per cycle. At this rate, each cycle doesn't produce a discrete monolayer. Since Atomic Layer growth occurs, and is user controlled, in terms of the number of cycles, film thickness is determined by the number of growth cycles. Thus the thickness/cycle representation for growth rate is more appropriate.[[User:jcrowland] 17 august 2006 (UFl)]

The growth rate is not always the same and may change with deposition temperature. Typical growth rates are 0.3-1.5 Angström per cycle. There are also so called "catalytic ALD processes" that show even higher growth rates per cycle.

Here is a standard reference that is often used in scientific ALD related publications:

Mikko Ritala and Markku Leskela, Atomic Layer Deposition, Handbook of Thin Film Materials, Vol. 1: Deposition and Processing of Thin Films, ed. H.S. Nalwa (2002) 103

Here is an excellent recent review paper: Niinisto, L., Paivasaari, J., Niinisto, J., Putkonen, M. and Nieminen, M., “Advanced electronic and optoelectronic materials by Atomic Layer Deposition: An overview with special emphasis on recent progress in processing of high-k dielectrics and other oxide materials,” Phys. Status Solidi A 201, 1443 (2004). 136.159.103.68 (talk) 20:59, 4 March 2008 (UTC)