Microstructural Investigation and Serial Section Tomography on ASIC chips for Assurance through Reverse Engineering Applications

Integrated Circuit (IC) reverse engineering has emerged as an important tool for security and authentication applications. In that context, the need for low-cost and efficient de-processing of IC chips has gained prominence in recent years. In this work, we have used a combination of acids to etch a silicon die down to its polysilicon level. The microstructural investigation using electron microscopy reveals different micron-sized gate-level structures like adders, switches, and shift registers. Cross-sectioning using Focused Ion Beam (FIB) milling exposes the inner metal layers, interlayer dielectric, and polysilicon layer. Finally, a FIB tomography is performed on the silicon die, and 3D reconstruction is performed on (8.76 x 5.1 x 4) mu m(3) volume.