Digital signal measurements with electric force microscope testing

Electric force microscope (EFM) testing is based on the non-linear Coulomb force interaction between a conducting EFM probe and a test point located o n the conducting line of an integrated circuit (IC), It has been reported a s a new and most promising testing system for IC internal contactless diagn osis without any IC preparation and without restrictions with respect to am bient conditions. But there are still very few testing techniques for the l ogic and the temporal analysis of digital signals, An experimental set-up t o solve this deficit is realized, The present state of the performance is d emonstrated by means of measurement results in the megahertz range. Pattern recognition and quantitative voltage measurements at distinct test points on a 1 mu m conducting line are presented. Furthermore, IC operation states on a three-line bus structure were characterized by the newly developed te sting techniques of stroboscopic voltage contrast and logic state mapping. The EFM now allows pattern recognition and characterization of internal IC operation states in correlation to topography. Copyright (C) 1999 John Wile y & Sons, Ltd.