Abstract
The mechanical properties of ultrathin films synthesized by atomic layer deposition (ALD) are critical for the liability of their coated devices. However, it has been a challenge to reliably measure critical properties of ALD films due to the influence from the substrate. In this work, we use the laser acoustic wave (LAW) technique, a non-destructive method, to measure the elastic properties of ultrathin Al2O3 films by ALD. The measured properties are consistent with previous work using other approaches. The LAW method can be easily applied to measure the mechanical properties of various ALD thin films for multiple applications.
Document Type
Article
Publication Date
8-11-2014
Digital Object Identifier (DOI)
http://dx.doi.org/10.1063/1.4892539
Funding Information
Q. Zhang is grateful for General Motors' summer internship program. The authors also acknowledges the support by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technologies Office of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, subcontract No. 7056410 under the Batteries for Advanced Transportation Technologies (BATT) Program. This project is also partial supported by National Science Foundation CMMI 1000726. We appreciate the help from Lars Haubold (Fraunhofer USA, Lansing, MI) for helping with the LAW system and Dr. Daad B Haddad (General Motors) for EPMA measurements.
Repository Citation
Zhang, Qinglin; Xiao, Xingcheng; Cheng, Yang-Tse; and Verbrugge, Mark W., "A Non-Destructive Method for Measuring the Mechanical Properties of Ultrathin Films Prepared by Atomic Layer Deposition" (2014). Chemical and Materials Engineering Faculty Publications. 6.
https://uknowledge.uky.edu/cme_facpub/6
Fig. 1 High-Resolution. Thickness of ALD Al<sub>2</sub>O<sub>3</sub> films. The thicknesses correspond to 50–250 reaction cycles and vary from 7.6 nm–37.9 nm as determined by XRR (filled circles). The growth rate is 1.51 Å/cycle (constant growth rate). Dashed line corresponds to the fit results to the XRR thickness data; triangles are measured density by XRR for all films, with an average density of 3.26 g/cm<sup>3</sup>; the density does not change much with the thickness/cycle number.
Figure 1.pptx (75 kB)
Fig. 1 Powerpoint. Thickness of ALD Al<sub>2</sub>O<sub>3</sub> films. The thicknesses correspond to 50–250 reaction cycles and vary from 7.6 nm–37.9 nm as determined by XRR (filled circles). The growth rate is 1.51 Å/cycle (constant growth rate). Dashed line corresponds to the fit results to the XRR thickness data; triangles are measured density by XRR for all films, with an average density of 3.26 g/cm<sup>3</sup>; the density does not change much with the thickness/cycle number.
2.tif (335 kB)
Fig. 2 High-Resolution. Dispersion curves (phase velocity versus frequency) for alumina-ALD samples: Solid-lines are LAW data; dashed lines are model fits; and the reaction cycles are shown in upper-right corner of each figure.
Figure 2.pptx (94 kB)
Fig. 2 Powerpoint. Dispersion curves (phase velocity versus frequency) for alumina-ALD samples: Solid-lines are LAW data; dashed lines are model fits; and the reaction cycles are shown in upper-right corner of each figure.
3.tif (118 kB)
Fig. 3 High-Resolution. Elastic modulus obtained from LAW. Except the thinnest film, 50 cycles (7.6 nm), the modulus is similar for all films and varies from 170 to 180 GPa.
Figure 3.pptx (60 kB)
Fig. 3 Powerpoint. Elastic modulus obtained from LAW. Except the thinnest film, 50 cycles (7.6 nm), the modulus is similar for all films and varies from 170 to 180 GPa.
Table 1.GIF (24 kB)
Table 1. Summary of the properties of different alumina ALD films.
Table 2.GIF (23 kB)
Table 2. Summary of elastic modulus of different alumina ALD film in literature and this work.
Notes/Citation Information
Published in Applied Physics Letters, v. 105, no. 6, article 061901, p. 1-4.
Copyright 2014 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
The following article appeared in Applied Physics Letters, v. 105, no. 6, article 061901, p. 1-4 and may be found at http://dx.doi.org/10.1063/1.4892539.