On overtravel and skate in cantilever-based probes for on-wafer measurements

Abstract

Abstract Due to the deformability of a microcantilever-based probe, there is an interesting and subtle interplay between the probe overtravel, the tip skate on the surface, and the ultimate tangency of the tip of the probe with the wafer surface. The relationship between these parameters is described here. The scalable model is tested using a macroscopic cantilever and found to be accurate in its predictions. In addition, to avoid potential skate-induced damage to metallisation, the idea of zero-skate using a cantilever-based probe has been introduced; minimal skate is demonstrated using a macroscopic cantilever—the skate can be reduced by a factor of 0.176. As the model is scalable, this information could be of use to the designer of emerging miniature microelectromechanical systems (MEMS) microcantilever-based surface contact probes destined for on-wafer electrical measurements or the test engineer concerned with on-wafer probe contacting—where skate and overtravel are important practical concerns having repercussions in electrical contact quality. Some predictions of the modelling for microcantilever-based probes are provided.