Advances in magnetic microscopy for stacked-die and package-level fault isolation

摘要

Recent advances have enabled magnetic-field imaging to identify high-resistance defects in packaged ICs within a resolution of 20μm on the device. This is done in a noncontact, nondestructive approach for several packaging technologies, including stacked die. For die-level applications, submicron resolution of HR defects can be achieved. High-resolution current mapping is achieved with two types of magnetic microscopes. One is a scanning fiber/superconducting quantum interference device (SQUID) microscope, which uses a SQUID sensor coupled to a nanoscale ferromagnetic probe. The second employs a magnetoresistive sensor.