Detecting reliability attacks during split fabrication using test-only BEOL stack

Split fabrication, the process of splitting an IC into an untrusted and trusted tier, facilitates access to the most advanced semiconductor manufacturing capabilities available in the world without requiring disclosure of design intent. While obfuscation techniques have been proposed to prevent malicious circuit insertion or modifications in the untrusted tier, detecting a pernicious reliability attack induced in the offshore foundry is more elusive. We describe a methodology for exhaustive testing of components in the untrusted tier using a specialized test-only metal stack for selected sacrificial dies.