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Advancing the Understanding of Manufacturing Tools for Hardware Security

Scrymgeour, David A.; Allemang, Christopher R.; Campbell, Deanna M.; Dominguez, Jason J.; Gao, Xujiao; Ivie, Jeffrey A.; Lu, Ping; Perry, Daniel L.; Stephens, Kelly S.; Titze, Michael; Vaidyanathan, Varun S.

This project’s goal was to explore new methods and tools to evaluate the focused ion beam (FIB) effect on active electrical devices, which is becoming increasingly challenged by the continual decrease in transistor geometry. Novel hole transfer methods leveraging FIB patterning were demonstrated utilizing selective area atomic layer deposition (ALD) and metal assisted chemical etching. A FIB damage electrical tester device was fabricated, and the effects of FIB beams were characterized by examining change in performance of damaged transistors. Detailed characterization of end-of-range damage for common FIB ions were correlated to modeling methods. Finally, undamaged and damaged devices were simulated by Charon to begin understanding the FIB effects on active devices. This test platform along with modeling methods give a powerful way to assess FIB damage in materials and devices, and with more development can help establish methods to predict FIB damage effects on electrical devices.

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Stress Intensity Thresholds for Development of Reliable Brittle Materials

Rimsza, Jessica M.; Strong, Kevin T.; Buche, Michael R.; Jones, Reese E.; Nakakura, Craig Y.; Weyrauch, Noah; Brow, Richard; Duree, Jessica M.; Stephens, Kelly S.; Grutzik, Scott J.

Brittle material failure in high consequence systems can appear random and unpredictable at subcritical stresses. Gaps in our understanding of how structural flaws and environmental factors (humidity, temperature) impact fracture propagation need to be addressed to circumvent this issue. A combined experimental and computational approach composed of molecular dynamics (MD) simulations, numerical modeling, and atomic force microscopy (AFM) has been undertaken to identify mechanisms of slow crack growth in silicate glasses. AFM characterization of crack growth as slow as 10-13 m/s was observed, with some stepwise crack growth. MD simulations have identified the critical role of inelastic relaxation in crack propagation, including evolution of the structure during relaxation. A numerical model for the existence of a stress intensity threshold, a stress intensity below which a fracture will not propagate, was developed. This transferrable model for predicting slow crack growth is being incorporated into mission-based programs.

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