B. D. Schrag, M. J. Carter, X. Liu, J. S. Hoftun, G. Xiao, Micro Magnetics, Inc., Fall River, MA

Summary: We present an in-depth discussion of the use of magnetic tunnel junction sensors to map currents for fault isolation in semiconductor die. First, a full case study is presented, in which faults are isolated in a new ASIC using magnetic current imaging with a scanning magnetic tunnel junction sensor probe. We also discuss the sensitivity and spatial resolution of magnetic tunnel junction sensors as compared with giant magnetoresistive sensors.