In-Situ Thickness Measurement of Die Silicon Using Voltage Imaging for Hardware Assurance

Hardware assurance of electronics is a challenging task and is of great interest to the government and the electronics industry. Physical inspection-based methods such as reverse engineering (RE) and Trojan scanning (TS) play an important role in hardware assurance. Therefore, there is a growing demand for automation in RE and TS. Many state-of-the-art physical inspection methods incorporate an iterative imaging and delayering workflow. In practice, uniform delayering can be challenging if the thickness of the initial layer of material is non-uniform. Moreover, this non-uniformity can reoccur at any stage during delayering and must be corrected. Therefore, it is critical to evaluate the thickness of the layers to be removed in a real-time fashion. Our proposed method uses electron beam voltage imaging, image processing, and Monte Carlo simulation to measure the thickness of remaining silicon to guide a uniform delayering process