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

 
: Kopycinska-Müller, Malgorzata; Clausner, André; Yeap, Kong Boon Oon; Köhler, Bernd; Kuzeyeva, Nataliya; Mahajan, Sukesh; Savage, Travis; Zschech, Ehrenfried; Wolter, Klaus-Jürgen

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Ultramicroscopy 162 (2016), pp.82-90
ISSN: 0304-3991
Deutsche Forschungsgemeinschaft DFG
KO-3825/1-1
Nanoscale properties of active polymer/organic-based electronic components by atomic forceacoustic microscopy
English
Journal Article
Fraunhofer IKTS ()
AFAM; AFM; elastic properties; porous materials; thin films

Abstract
The indentation modulus of thin films of porous organosilicate glass with a nominal porosity content of 30% and thicknesses of 350 nm, 200 nm, and 46 nm 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 350 nm and 200 nm thin films were respectively 6.3 GPa±0.2 GPa and 7.2 GPa±0.2 GPa and free of the substrate influence. The sample with the thickness of 46 nm was tested in four independent measurement sets. Cantilevers with two different tip radii of about 150 nm and less than 50 nm 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 8.3 GPa±0.4 GPa 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.

: http://publica.fraunhofer.de/documents/N-375170.html