Thermal Frequency Imaging for localization of Buried Back End of Line defects
Thermal Frequency Imaging for localization of Buried Back End of Line defects
Wednesday, October 7, 2026: 9:20 AM
Summary:
Localization of buried Back End of Line (BEOL) defects, such as MIM dielectric breakdowns and vertical interconnect shorts, remains a major challenge when conventional techniques including Photon Emission Microscopy (PEM), Thermally Induced Voltage Alteration (TIVA), and Lock‑In Thermography (LIT) often detect secondary or induced signals that do not directly correspond to the primary defect, complicating subsequent physical analysis. This work demonstrates the use of Thermal Frequency Imaging (TFI), a thermo‑reflectance signal component inherent to Laser Voltage Imaging (LVI), as a practical and effective approach for localizing buried BEOL defects. Unlike prior LVI based approaches that rely on schematic correlation or dynamic test access, TFI is applied here as a standalone technique, well suited for foundry environments with limited design visibility. Firstly, this paper presents experimental results to establish the detectability of TFI signals in buried BEOL structures using LVI setup. Subsequently, three product‑level case studies are presented, including MIM dielectric breakdown, metal‑to‑poly and metal‑to‑metal vertical shorts, all of which were not successfully localized using PEM, TIVA, or LIT. In each case, TFI enabled precise defect localization for FIB cross‑sectioning. These results highlight TFI as a valuable complement to conventional static fault isolation techniques, significantly improving localization confidence and analysis efficiency for complex, buried BEOL defects.
Localization of buried Back End of Line (BEOL) defects, such as MIM dielectric breakdowns and vertical interconnect shorts, remains a major challenge when conventional techniques including Photon Emission Microscopy (PEM), Thermally Induced Voltage Alteration (TIVA), and Lock‑In Thermography (LIT) often detect secondary or induced signals that do not directly correspond to the primary defect, complicating subsequent physical analysis. This work demonstrates the use of Thermal Frequency Imaging (TFI), a thermo‑reflectance signal component inherent to Laser Voltage Imaging (LVI), as a practical and effective approach for localizing buried BEOL defects. Unlike prior LVI based approaches that rely on schematic correlation or dynamic test access, TFI is applied here as a standalone technique, well suited for foundry environments with limited design visibility. Firstly, this paper presents experimental results to establish the detectability of TFI signals in buried BEOL structures using LVI setup. Subsequently, three product‑level case studies are presented, including MIM dielectric breakdown, metal‑to‑poly and metal‑to‑metal vertical shorts, all of which were not successfully localized using PEM, TIVA, or LIT. In each case, TFI enabled precise defect localization for FIB cross‑sectioning. These results highlight TFI as a valuable complement to conventional static fault isolation techniques, significantly improving localization confidence and analysis efficiency for complex, buried BEOL defects.