This Small Business Technology Transfer (STTR) Phase I project will develop a hybrid scanning-SQUID microscope coupled to a magnetic flux-guide to achieve nanoscale imaging of weak buried currents in a large range of packaged microelectronic devices. The manufacture of integrated circuits has become an increasingly complex nanoscale technology. With these dimensions, the propensity for the formation of shorts or high resistance defects (resistive opens) at the metal layers is increasing where "killer defects" may be non-visual and only be a few tens of nanometers in size. This is leading the industry toward a gap between the fault isolation tools of today (many of which are optical and wavelength-limited to 500 nm resolution) and the atomic scale defect imaging tools like AFMs and STMs. The needed tools must have nanoscale resolution and a probe geometry capable of working in milled cavities due to the complex packaging schemes. The goals of this Phase I project are to achieve current images with a sensitivity of ~50 nA and a resolution ~100 nm in milled cavities. This will be achieved through innovative probe design optimized for sensitivity with a submicron tip that can be rapidly scanned in a non-contact mode. Commercially, the technology development that is proposed in this program is of critical interest to major semiconductor manufacturers, as well as all other semiconductor manufacturers working on advanced integrated circuits. For semiconductor companies it will enable the design centers to speed design, Fab labs to accelerate manufacturing process development for new products, and to accelerate time-to-yield. Overall, it means faster time-to-market. For the nation, it means faster introduction of advanced electronics that will have a broad impact across all industries and ultimately improve quality of life and labor productivity.