Morphology Analysis of Cu Film Fractures in Sandwiched Methylmethacrylate Plates

Abstract

Thin films of Cu were evaporated on solid plates of polymethylmethacrylate (PMMA). A polymerization process was made to realize sandwiched structure to protect the Cu films. Fracturing of the metal film surface was observed with several morphologies showing two different fracture systems. Surface film morphology was analysed in terms of the distribution area of the islands and contour fractal dimension. The island areas showed a maximum corresponding to 42 nm of the Cu thickness, it was also the threshold to observe the second fracture system. The fractures pattern resulted to be scale invariant with fractal dimensions between 1.55 and 1.7. The minimum fractal dimension also occurred at the film thickness corresponding to the maximum island area. The reported effects can be understood on the basis of different thermal expansion coefficients of the two materials and their thermally induced adhesion.

DOI: http://dx.doi.org/10.5755/j01.ms.21.2.6518