Cooperation between adsorbates accounts for the activation of atomic layer deposition reactions

Nanoscale
Mahdi Shirazi, Simon D Elliott

Abstract

Atomic layer deposition (ALD) is a technique for producing conformal layers of nanometre-scale thickness, used commercially in non-planar electronics and increasingly in other high-tech industries. ALD depends on self-limiting surface chemistry but the mechanistic reasons for this are not understood in detail. Here we demonstrate, by first-principle calculations of growth of HfO2 from Hf(N(CH3)2)4-H2O and HfCl4-H2O and growth of Al2O3 from Al(CH3)3-H2O, that, for all these precursors, co-adsorption plays an important role in ALD. By this we mean that previously-inert adsorbed fragments can become reactive once sufficient numbers of molecules adsorb in their neighbourhood during either precursor pulse. Through the calculated activation energies, this 'cooperative' mechanism is shown to have a profound influence on proton transfer and ligand desorption, which are crucial steps in the ALD cycle. Depletion of reactive species and increasing coordination cause these reactions to self-limit during one precursor pulse, but to be re-activated via the cooperative effect in the next pulse. This explains the self-limiting nature of ALD.

References

Jan 1, 1993·Physical Review. B, Condensed Matter·G Kresse, J Hafner
Nov 26, 2003·Angewandte Chemie·Markku Leskelä, Mikko Ritala
Feb 1, 2005·Science·K HonkalaJ K Nørskov
Mar 3, 2007·Nature Materials·A K Geim, K S Novoselov
Jun 3, 2008·The Journal of Chemical Physics·Alexander SlepoySteven J Plimpton
Aug 14, 2008·Journal of the American Chemical Society·Atashi B MukhopadhyayJavier Fdez Sanz
Dec 22, 2010·The Journal of Chemical Physics·D J MillerA Nilsson
Jun 22, 2012·Nano Letters·Luda WangJ Scott Bunch
Jan 24, 2013·Nano Letters·F K PerkinsB T Jonker
Nov 20, 2013·Journal of Computational Chemistry·Mahdi Shirazi, Simon D Elliott

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Citations

Jun 16, 2015·Physical Chemistry Chemical Physics : PCCP·Timo Weckman, Kari Laasonen
Jun 13, 2018·Physical Chemistry Chemical Physics : PCCP·M ShiraziA A Bol
Nov 9, 2018·The Journal of Physical Chemistry. C, Nanomaterials and Interfaces·Timo Weckman, Kari Laasonen
Jul 17, 2019·Langmuir : the ACS Journal of Surfaces and Colloids·V Vandalon, W M M Erwin Kessels

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