Dresden 2009 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 17: Mechanical Properties III

MM 17.5: Talk

Tuesday, March 24, 2009, 11:15–11:30, IFW D

Measurement of mechanical properties for materials of interest in microelectronics using indentation methods: porous low-k dielectric and soft metallic thin films as examples — •Matthias Herrmann and Frank Richter — Institute of Physics, Chemnitz Univ. of Technol., 09107 Chemnitz, Germany

For the characterisation of the mechanical behaviour of bulk and thin film materials, physical quantities like Young’s modulus E, Poisson’s ratio ν, or yield strength Y are most appropriate and can principally be used for modelling and/or predicting materials under load. In contrast to these quantities, the often used hardness depends on the applied measuring method and is less suited for modelling. However, the determination of these properties is difficult because it is distorted by the influence of the substrate. Additionally, problems can arise when the investigated materials start to plastically deform already at very low loads.

In this contribution, indentation methods have been applied to two such special cases: mesoporous SiO₂ as well as MSQ-based films with porosities of 0.30-0.57 and copper films. To determine their Y and E, e.g. elastic-plastic indentations using spheres and sharp tips have been performed, which were analysed by Pharr’s concept of the effective indenter. We found Y values between 75-150 MPa for SiO₂ and MSQ films which decreased with increasing porosity. They indicate a tendency to easily plastically deform. The E of these films were between 1-4 GPa. General difficulties with the measurement of plastically deforming materials are exemplarily discussed for the copper films.