High Aspect Ratio, Vertical Bipolar Junction Transistor NPN Device Fault Isolation & Analysis Techniques

Analog components are still an important aspect of our society's electronic portfolio. They play a role in the emerging and expanding 5G electronic industry, for instance. The NPN bipolar junction transistor (BJT) is the foundation of many analog circuits and has continually evolved to meet more demanding specifications [1], [2]. Certain embodiments of these NPNs pose difficulties in failure analysis. One such embodiment is a vertical NPN BJT with high aspect ratio dimensions. Specifically, the dimensions involved are nanometer thick NP & PN junctions that extend microns in length. These dimensions provide desired performance improvements but a subtle, nanometer scale defect present anywhere along this length can cause substantial electrical shifts detrimental to an analog circuit. Several simple and complex techniques using common failure analysis tools can isolate these defects as discussed in this paper.