Wide-Field Quantum Diamond Magnetic Microscopy at Nanotesla Sensitivity for Non-Destructive Semiconductor Failure Analysis

Abstract

Failure analysis (FA) of advanced semiconductor packages is increasingly constrained by the inability of established techniques to image faults buried inside 2.5D and 3D integrated devices. Magnetic current imaging offers a non-destructive route to localising buried currents through opaque packaging, but no existing instrument combines the sensitivity, standoff, spatial resolution, and room-temperature operation required for routine FA use. Wide-field quantum diamond magnetic microscopes (QDMs), based on nitrogen-vacancy centers in diamond, provide a room-temperature implementation with vector-field readout, yet camera-based readouts have so far capped their magnetic sensitivity at the microtesla level. Here we report a QDM prototype that replaces the CMOS camera with a custom photodiode-based detector, reaching a median sensitivity of 2.6 nT/√Hz - a roughly thousandfold improvement over camera-limited QDMs. We benchmark the prototype against EMMI, OBIRCH, and LIT on a commercial automotive ASIC, reconstructing the two-dimensional current density from a single vector-field acquisition, and demonstrate localisation of a short in a silicon-carbide MOSFET at signal-to-noise ratio above five with 1 ms of per-pixel integration time. These results bring magnetic current imaging into the sensitivity, throughput, and standoff regime required for routine FA of buried and through-package faults in 2.5D and 3D devices, and open a path toward near-line use in advanced-packaging production.