Abstract
The conformality of a film grown by atomic layer deposition (ALD) is strongly affected by the reactivities of the precursor and coreactant, which can be expressed in terms of their sticking probabilities toward the surface. We show that the leading front of the thickness profile in high-aspect-ratio structures gives direct information on the sticking probabilities of the reactants under most conditions. The slope of the front has been used to determine the sticking probabilities of Al(CH3)3 and H2O during ALD of Al2O3 . The determined values are (0.5-2) × 10-3 for Al(CH3)3 and (0.8-2) × 10-4 for H2O at a set-point temperature of 275 °C, corresponding to an estimated substrate temperature of ∼220 °C. Additionally, the thickness profiles reveal soft-saturation behavior during the H2O step, most dominantly at reduced temperatures, which can limit the conformality of Al2O3 grown by ALD. This work thus provides insights regarding quantitative information on sticking probabilities and conformality during ALD, which is valuable for gaining a deeper understanding of ALD kinetics.
Original language | English |
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Article number | 030908 |
Journal | Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films |
Volume | 37 |
Issue number | 3 |
DOIs | |
Publication status | Published - 24 Apr 2019 |
MoE publication type | A1 Journal article-refereed |
Funding
This work is part of the research program HTSM with Project No. 15352, which is ( partly) financed by the Netherlands Organization for Scientific Research (NWO). VTT acknowledges the financial support for developing the LHAR3 conformality test structure from the Academy of Finland through the Finnish Centre of Excellence on Atomic Layer Deposition and from Business Finland (National Innovation Funding Center of Finland, previously: Tekes) through the PillarHall TUTL project.
Keywords
- OtaNano