Electromagnetic Tensile Adhesion Test Method

A method is described for applying a known tensile stress to a thin-film structure without requiring any mechanical attachment to the film. The stress is developed by the interaction of an external magnetic field with an electric current through a suitably patterned specimen of the film to be evaluated. An apparatus for producing the required magnetic fields and electric currents is described, and procedures are given for preparing suitable test specimens using conventional electronic device fabrication technology. Results showing the use of this technique for measuring the adhesion of evaporated copper on thermally oxidized silicon are presented. The maximum stress which can be produced is limited by the available magnetic field, the fabrication of the test structure, and the heating effect of the current through this structure. These factors are discussed, and it is shown that useful stresses of at least 24 000 psi (165 600 kPa) are practical by the electromagnetic method.