Mechanical characterization of porous nano-thin films by use of atomic force acoustic microscopy

M Kopycinska-Müller; A Clausner; K-B Yeap; B Köhler; N Kuzeyeva; S Mahajan; T Savage; E Zschech; K-J Wolter

doi:10.1016/j.ultramic.2015.12.001

Mechanical characterization of porous nano-thin films by use of atomic force acoustic microscopy

Ultramicroscopy. 2016 Mar:162:82-90. doi: 10.1016/j.ultramic.2015.12.001. Epub 2015 Dec 9.

Authors

M Kopycinska-Müller¹, A Clausner², K-B Yeap², B Köhler², N Kuzeyeva², S Mahajan³, T Savage³, E Zschech⁴, K-J Wolter⁵

Affiliations

¹ Fraunhofer Institute for Ceramic Technologies and Systems - Material Diagnostics IKTS-MD, Maria Reiche Str. 2, 01109 Dresden, Germany; Faculty of Electrical Engineering and Information Technology, Technical University Dresden, Helmholtz Str. 18, 01069 Dresden, Germany. Electronic address: Malgorzata.Kopycinska-Mueller@ikts.fraunhofer.de.
² Fraunhofer Institute for Ceramic Technologies and Systems - Material Diagnostics IKTS-MD, Maria Reiche Str. 2, 01109 Dresden, Germany.
³ SBA Materials, Inc., 9430-H San Mateo Blvd NE, Albuquerque, NM 87113, USA.
⁴ Fraunhofer Institute for Ceramic Technologies and Systems - Material Diagnostics IKTS-MD, Maria Reiche Str. 2, 01109 Dresden, Germany; Faculty of Electrical Engineering and Information Technology, Technical University Dresden, Helmholtz Str. 18, 01069 Dresden, Germany.
⁵ Faculty of Electrical Engineering and Information Technology, Technical University Dresden, Helmholtz Str. 18, 01069 Dresden, Germany.

PMID: 26799327
DOI: 10.1016/j.ultramic.2015.12.001

Abstract

The indentation modulus of thin films of porous organosilicate glass with a nominal porosity content of 30% and thicknesses of 350nm, 200nm, and 46nm is determined with help of atomic force acoustic microscopy (AFAM). This scanning probe microscopy based technique provides the highest possible depth resolution. The values of the indentation modulus obtained for the 350nm and 200nm thin films were respectively 6.3GPa±0.2GPa and 7.2GPa±0.2GPa and free of the substrate influence. The sample with the thickness of 46nm was tested in four independent measurement sets. Cantilevers with two different tip radii of about 150nm and less than 50nm were applied in different force ranges to obtain a result for the indentation modulus that was free of the substrate influence. A detailed data analysis yielded value of 8.3GPa±0.4GPa for the thinnest film. The values of the indentation modulus obtained for the thin films of porous organosilicate glasses increased with the decreasing film thickness. The stiffening observed for the porous films could be explained by evolution of the pore topology as a function of the film thickness. To ensure that our results were free of the substrate influence, we analyzed the ratio of the sample deformation as well as the tip radius to the film thickness. The results obtained for the substrate parameter were compared for all the measurement series and showed, which ones could be declared as free of the substrate influence.

Keywords: AFAM; AFM; Elastic properties; Porous materials; Thin films.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.