Applications of PVC and Progressive FIB Milling in Identifying Top-Down Invisible Defect on Advanced Nodes SRAM Devices

Passive voltage contrast (PVC) is a well-known fault isolation technique in differentiating contrast at via/metal/contact levels while focused ion beam (FIB) is a destructive technique specifically used for cross sectioning once a defect is identified. In this study, we highlight a combination technique of PVC and progressive FIB milling on advanced node fin field-effect transistor (FinFET) for root cause analysis. This combo technique is useful when applied on high-density static random access memory (SRAM) structure, especially when it is difficult to view the defect from top-down inspection. In this paper, we create a FA flow chart and FIB deposition/milling recipe for SRAM failure and successfully apply them to three case studies.