Talk:Atomic layer deposition

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  • Why is the cost of the substrate relevant for the merit of ALD. You have a substrate and want to deposit on it with CVD/ALD/PVD.
  • Apart from very exceptional cases, how do the impurities in the substrate impact the ALD process?
  • The table "ALD Reaction Mechanisms Summary Table" has too many mistakes.

I fully concur that there are many inaccuracies, generalizations, and just mistakes on the page. The structure is also sub-par. Hopefully, I will have some time to work on updating the page. (talk) 15:30, 3 February 2017 (UTC)

Merge ALD and ALE[edit]

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.

ALD citations needed[edit]

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). (talk) 20:59, 4 March 2008 (UTC)

Incorrect Information[edit]

A monolayer size of ~0.1 Angstroms is not realistic. Check out the periodic table and the atomic radius of common ALD elements. They are all much larger than that. Did the author mean 0.1 nm? —Preceding unsigned comment added by (talk) 13:20, 27 June 2008 (UTC)

The concept of monolayer coverage is related to both the density of reactive sites on the surface and the steric hindrance of the precursor (how many precursor molecules can you efficiently pack on the surface). Therefore, it does not have to be the same as the atomic radius. Generally it ranges between 1 and 0.2 Angstroms per cycle and 0.1 Angstroms per cycle is also feasible. (talk) 02:41, 18 April 2012 (UTC)

ALD and ALE is exactly the same thing, I vote for merging. —Preceding unsigned comment added by Erik.oestreng (talkcontribs) 09:35, 18 November 2009 (UTC)


The grammar in the introduction needs some work. I am by no means an English major so I have not made any changes but if someone would, it would improve the article.

I have rewritten the introduction. Anglyan (talk) 04:30, 30 December 2014 (UTC)anglyan

Why Boltzmann?[edit]

Honestly, I don't understand why the transport of reactants in an ALD reactor is phrased in terms of the Boltzmann equation for ALD. I think this is unnecessarily complex, and the same equation can be rephrased as a plug flow model that is more accessible. As early as in 1995 Ylilammi used this model to reproduce growth profiles in ALD (see M. Ylilammi, J. Electrochem. Soc. 142, 2474 (1995)). Unless there are any good reasons I will update this section when I have time.

Anglyan (talk) 04:41, 30 December 2014 (UTC)anglyan

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History of ALD[edit]

At the moment there is a general worldwide volunteer-based history project on ALD going on called Virtual Project on the History of ALD (VPHA), project webpage (related blog: One of the items of the Publication Plan of VPHA is to update Wikipedia what comes to the history of ALD (#11, Soon we plan to significantly re-write the history section, according to the information that has been gathered in VPHA. Everybody who has been active in updating the Wikipedia ALD pages, is welcome to join VPHA. In addition to updating Wikipedia, we are also generating joint publications, the next one will be at the ALD 2016 conference in Ireland (deadline to join there as an author is Feb 7, 2016). What the history section at the moment needs is a notion that ALD has been developed independently twice. Also it has appeared that the Aleskovskii thesis does not yet contain a proposal for the concept of ALD, only of the "Matrix hypothesis". Anyone interested in joining the VPHA presentations and Wikipedia update effort is welcome to do so. As of January 2016, things are moving on; we are discussing in Twitter with hashtag #WikiALD. Posts in the ALD History Blog about Wikipedia updates can be found here: Also it is noteworthy that Wikimedia Commons has now an own category "Atomic Layer Deposition", to collect together media files related to this topic. Rlpuu (talk) 11:08, 23 January 2016 (UTC)

I have done my edits for now --- practically completely rewritten. Most references are the same, though. Rlpuu (talk) 20:38, 23 January 2016 (UTC)

Adding articles for specific processes[edit]

I'm considering writing articles on some of the more heavily used ALD processes, like the thermal trimethylaluminum/water Al2O3 process and the thermal TDMAH/water HfO2 one. Would that be appropriate? I've never written a Wikipedia article, so I have a hard time gauging that. Dakane2 (talk) 04:15, 15 August 2017 (UTC)