Measurement of mechanical properties for dense and porous polymer films having a low dielectric constant

We measured the mechanical properties of dense and porous polymeric films, the modified polyarylethers, which have a low dielectric constant varying f rom 2.7 to 1.8, by combining three different methods; membrane bulge test, nanoindentation, and single-substrate bending beam method. The elastic modu lus and initial stress measured from these three methods are in good agreem ent. The substrate effect was observed in the measurements by nanoindentati on. Data obtained by nanoindentation show a significant dependence on the f ilm thickness and the displacement depth of the indenter. However, the hard ness of the low dielectric constant thin film does not depend on thickness and only slightly depends on the indentation depth. A tentative analysis is proposed to explain the results. (C) 2000 American Institute of Physics. [ S0021-8979(00)10217-8].