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Saturation Profile Based Conformality Analysis for Atomic Layer Deposition: Aluminum Oxide in Lateral High-Aspect-Ratio Channels

revised on 23.09.2020, 09:13 and posted on 23.09.2020, 12:42 by Jihong Yim, Oili Ylivaara, Markku Ylilammi, Virpi Korpelainen, Eero Haimi, Emma Verkama, Mikko Utriainen, Riikka Puurunen

ABSTRACT: Atomic layer deposition (ALD) raises global interest through its unparalleled conformality. This work describes new microscopic lateral high-aspect-ratio (LHAR) test structures for conformality analysis of ALD. The LHAR structures are made of silicon and consist of rectangular channels supported by pillars. Extreme aspect ratios even beyond 10 000:1 enable investigations where the adsorption front does not penetrate to the end of the channel, thus exposing the saturation profile for detailed analysis. We use the archetypical trimethylaluminum (TMA)-water ALD process to grow alumina as a test vehicle to demonstrate the applicability, repeatability and reproducibility of the saturation profile measurement and to provide a benchmark for future saturation profile studies. Through varying the TMA reaction and purge times, we obtained new information on the surface chemistry characteristics and the chemisorption kinetics of this widely studied ALD process. We propose new saturation profile related classifications and terminology.


Academy of Finland COOLCAT consortium, decision no. 329978

Academy of Finland Finnish Centre of Excellence on Atomic Layer Deposition

Tekes (Business Finland) TUTL PillarHall

Aalto University starting grant

Academy of Finland ALDI consortium, decision no. 331082


Email Address of Submitting Author


Aalto University School of Chemical Engineering



ORCID For Submitting Author


Declaration of Conflict of Interest

R.L.P developed the concept of the microscopic LHAR conformality test and is the inventor of a related patent application. VTT has made PillarHall™ test structure prototypes available for purchase. M.U. is re-sponsible for PillarHall™ test structure sales and commercialization activities at VTT and is the founder of Chipmetrics Oy.

Version Notes

Second revised version to be submitted to journal, with the supporting information included as one file. (Update info 23.9.2020)