Scrub marks 3D inspection provide a feedback opportunity to the test engineer to identify and correct many problems, which have a dramatic impact on test yield such as probe-to-probe planarization (difference in depth of the scrub marks), to identify worn-out probes (wider scrub marks), to check the system planarity (inhomogeneous depths and lengths of marks for one probe), and to control the overdrive (additional vertical motion of the device chuck).

Careful analysis of probe marks will allow the test engineer to follow the trail of clues to improved test performance. This analysis is usually performed by vertically scanning systems at the cost of low throughput. PhaseView's optical instruments can perform 3D analysis of the scrub marks with vertical resolution of 10 nm and lateral resolution of 0.5 μm.