Current imaging, EBIC/EBAC, and electrical probing combined for fast and reliable in situ electrical fault isolation
Abstract Using a compact nanoprobing setup comprising eight probe tips attached to piezo-driven micromanipulators, various techniques for fault isolation are performed on 28 nm samples inside an SEM. The employed techniques include nanoprobing as well as EBAC. The recently implemented Current Imaging technique is used to quickly image large arrays of contacts providing a means of locating faults. In this case, Current Imaging provides insight into the sample's behaviour yielding qualitatively comparable results to the more cumbersome cAFM technique. While the results of the TEM investigations including EDX mappings were inconclusive, the Current Imaging technique clearly shows that the root cause is located below the SiGe layer. By combining these techniques inside a FIB/SEM microscope, it is possible to locate and characterize a failure as well as prepare a TEM lamella for further investigation without the necessity to switch to a different tool.
Resistive contrast imaging applied to multilevel interconnection failure analysis
Resistive contrast imaging (RCI) is a new failure analysis technique that uses a scanning electron microscope to generate a relative resistance map of an integrated circuit. The RCI map can be used to localize abrupt changes in resistance and verify continuity. Results using RCI on several two-level interconnection devices are described. The images demonstrate how RCI can be used to differentiate between levels and to localize metal shorts and opens. Methods for improving image quality and level differentiation as well as future development work are discussed.<<ETX>>
Resistive contrast imaging: A new SEM mode for failure analysis
Semiconductor device path resistance is obtained from scanning electron microscope (SEM) images using a modified electron-beam-induced current (EBIC) mode. We call this new method resistance contrast imaging (RCI). The intensity of these images is proportional to internal device resistance ratios. Applications of the RCI method to device failure analysis are presented. This method is non-destructive and applicable to passivated devices.